Dark Matter Direct Searches and the Anomalous Magnetic Moment of Muon

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暗物质成品

What is dark matter?
About 65 years ago, the first time that evidence of the existence of dark matter. At that time, Fulizizha Popovich found a large cluster of galaxies in the galaxy has a very high velocity, unless the quality of galaxy clusters is based on the number of calculations in which stars are more than 100 times the value, or cluster of galaxies can not bound lives of these galaxies. After decades of observation and analysis confirmed this. Although the nature of dark matter is still unknown, but by 80 years, accounting for about 20% of the energy density of dark matter to be widely accepted.
What is dark matter?
now we know that dark matter has become an important part of the universe. The total mass of dark matter is ordinary matter, 6.3 times the energy density in the universe, accounting for 1 / 4, but also important is that dark matter dominated the formation of cosmic structures. Now the nature of dark matter remains a mystery, but assuming it is a weak interaction of subatomic particles, then the resulting large-scale structure of the universe is consistent with the observations. Recently, however, the structure of galaxies and galaxy subanalysis shows that this assumption and the difference between observations, which at the same time provide a variety of possible dark matter theory was useless. Small-scale structure through the density, distribution, evolution and its environment studies can distinguish between these potential dark matter model for the nature of dark matter to bring a new dawn.

Planned Dark Matter searches with the MAGIC Telescope

a r X i v :a s t r o -p h /0505313v 1 15 M a y 2005Planned Dark Matter searches with the MAGIC Telescope JOSEP FLIX for the MAGIC Collaboration Institut de F´ısica d’Altes Energies Ediﬁci Cn,Universitat Autonoma de Barcelona,08193,Spain The MAGIC 17m-diameter Imaging Air Cherenkov Telescope (IACT)has been commissioned beginning of 2005.The telescope has been designed to achieve the lower detection energy threshold ever obtained with an IACT,about 50GeV.A new window in γ-ray astronomy is being opened with great impact for exciting new physics and new discoveries.Among the targets of MAGIC is the indirect detection of Dark Matter (DM).We have considered diﬀerent DM halo models of high DM density objects like the center of the Milky Way,its closest satellites and nearby galaxies (M31,M87).For each object,detection limits are computed for diﬀerent DM halo models in a mSUGRA scenario for supersymmetric neutralino annihilation γ-ray production.Advantages and drawbacks of these objects and plans for future observationsare discussed.1IntroductionAt present,the nature of Dark Matter is still unknown,and none of the known particles satisfy all requirements to account for it.A number of viable Weakly Interacting Massive Particle (WIMP)candidates have been proposed within several theoretical frameworks,mainly motivated by extensions of the standard model of particle physics,e.g.supersymmetry (SUSY).Among this variety of particles,the most plausible candidate is the neutralino 1(χ).Any WIMP candidate (SUSY or not)may be detected directly via elastic scattering with targets in the Earth.There are several dedicated experiments already exploiting this detection technique,but they do not claim any strong and solid detection up to now (see review 2).Complementary,neutralinos might be indirectly detected by their self-annihilation products in high-density Dark Matter environments.In particular,channels that produce gamma-rays are interesting because γ-rays are not deﬂected by magnetic ﬁelds and preserve the information of the original annihilation region,i.e.they act as tracers of the Dark Matter density distribution.This continuum gamma-ray spectra may be indirectly observed by means of IACTs.2The MAGIC ExperimentTo date,the Major Atmospheric Imaging Cerenkov telescope(MAGIC3)is the largest world-wide Imaging Air Cerenkov Telescope(IACT).Located on the Canary Island La Palma(2200m a.s.l),the telescope has a17m diameter high reﬂectivity tessellated parabolic mirror dish, mounted on a light weight carbonﬁber frame.It is equipped with a high eﬃciency576-pixel photomultiplier camera,whose analogue signals are transported via opticalﬁbers to the trigger electronics and the300MHz FADC readout.Its physics program comprises,among other topics, pulsars,supernova remnants,active galactic nuclei,micro-quasars,gamma-ray bursts and Dark Matter.Several positive detections of already knownγ-ray emitters have been already accomplished during its initial phase(see contributions to these proceedings from N.Tonello[1ES1959+650], M.L´o pez[Crab Nebula]and D.Mazin[Mrk-421]).Coping with the hadronic background below 100GeV presents a new challenge,but these observations evidence that MAGIC analysis extends well below100GeV and,encouragingly enough,evenγ-rays with an estimated energy of50 GeV trigger the telescope.The analysis methods are presently being adapted to the low-energy domain,uncharted territory as yet.Meanwhile,the collaboration is involved in the construction of a second telescope(MAGIC-II,see A.Moralejo contribution to these proceedings).This will improve the angular and spectral resolution andﬂux sensitivity of the system.3Gamma-rays from neutralino annihilationsNeutralino annihilation can generate continuumγ-ray emission,via the processχχ→q¯q.The subsequent decay ofπ0-mesons created in the resulting quark jets produces a continuum ofγ-rays.The expected annihilationγ-rayﬂux above an energy E thresh arriving at Earth is given by:dNγ(Eγ>E thresh)2·σv3.1Galactic CenterThe presence of a Dark Matter halo in the Milky Way Galaxy is well established by stellar dynamics.In particular,stellar rotation curve data of the Milky Way can be adjusted byﬁtting with the use of universal DM proﬁles predicted by simulations.The most recent models include an eﬀect that had been previously neglected and aﬀects the DM density at the center of the Milky Way halo,namely the compression of the Dark Matter due to the infall of baryons to the innermost region5.As Dark Matter density is enhanced at the center the expected signal is boosted.This model is based on a large amount of observational data of our galaxy and is in good agreement with the brand new cosmological simulations for the response of Dark Matter halos to condensation of baryons6.Such a central spike in the center of the galaxy is under debate and depend on the Black Hole history during galaxy formation.There exist some evidences against a central cusp,but they must be taken with caution(see F.Ferrer in these proceedings).We consider an uncompressed NFW DM halo model7and the adiabatic contracted NFW proﬁle5.3.2Draco dwarf spheroidal and nearby galaxiesThe Milky Way is surrounded by a number of small and faint companion galaxies.These dwarf satellites are by far the most Dark Matter dominated known objects,with Mass-to-Light ratios from30to300.Draco is the most DM dominated dwarf satellite.DM density proﬁles derived from Draco stars cannot diﬀerentiate between cusped or cored proﬁles in the innermost region, as data are not available at small radial distances.Moreover,observational data disfavors tidal disruption eﬀects,which may aﬀect dramatically the DM distribution in Draco.In order to compare with the Galactic Center we adopt the very recent cusped DM model which includes new available Draco data8.In addition,we adopted NFW models for the nearby galaxy M319and the Virgo Cluster10. These NFW proﬁles do not take into account any enhancement eﬀect,like adiabatic contraction or presence of DM substructures.4SummaryFigure1shows exclusion limits for MAGIC in the mSUGRA plane Nγ(Eγ>E thresh) σv vs. mχfor the four most promising sources considered.The nominal energy threshold E thresh has been assumed to be conservatively100GeV and has been accordingly scaled with the zenith angle observation,as well as the telescope collection area.The expectedﬂuxes are rather low and depends strongly on the innermost density region of the DM halos considered.The detection of a DMγ-ray signal from the Galactic Center is possible(or achievable)in case of a very high density DM halo,like the one predicted by adiabatic contraction processes(expected improvements on the E thresh allows to test a signiﬁcant portion of the SUSY parameter space).Theﬂux measured by the HESS(see L.Rolland in these proceedings)experiment is far above the theoretical expectations(it extends to the TeV regime), indicating that the observed gamma radiation is most probably not due to the annihilation of SUSY-neutralino Dark Matter particles.Nevertheless,other models like Kaluza-Klein Dark Matter are not ruled out.It is interesting to investigate and characterize the observed gamma radiation to constrain the nature of the emission.In addition,it is not excluded that a part of theﬂux is due to Dark Matter annihilation.Due to the large zenith angle for Galactic Center observations,MAGIC will have a large energy threshold but also a large collection area and good statistics at the highest energies.Galactic Center observations are foreseen from April to August200511.Figure1:Exclusion limits for the four most promising sources of Dark Matter annihilation radiation.The Galactic Center is expected to give the largestﬂux(lowest exclusion limits)amongst all sources.In the long term we consider Draco as a plausible candidate for Dark Matter inspired observa-tions.Conservative scenarios give lowﬂuxes which are not detectable by MAGIC in a reasonable observation time.However,there are several factors that might enhance the expectedﬂux from neutralino annihilations in Draco.Other Dark Matter particles,like Kaluza-Klein particles,may produce gamma-rays,maybe with a higherﬂux than those quoted here.Draco is the most DM dominated dwarf(M/L up to300)and an object where no otherγ-ray emission is expected. Low zenith angle observations will preserve the nominal(low)E thresh of the MAGIC telescope. Moreover,no known VHE emitters in the FOV provides no otherγ-ray sources in competition to the one predicted in the exposed DM scenario.4.1AcknowledgmentsI am grateful to the Conference Organizers for a very enjoyable week and Conference in La Thuille and to all the members of the MAGIC Dark Matter working group for fruitful discussions.References1.G.Jungman,M.Kamionkowski and K.Griest,Physics Reports,267,195-373(1996)2.J.Gascon,astro-ph/05042413.J.Cortina for the MAGIC Collaboration,Astrophys.Space Sci.297,245-255(2005)4.J.Navarro,C.Frenk and S.White,ApJ490,493(1997)5.F.Prada,A.Klypin,J.Flix et al.,Phys.Rev.Lett.93,241301(2004)6.O.Gnedin et al.,Astrophys.J.61616-26(2004)7.N.Fornengo et al.,Phys.Rev.70103529(2004)8.E.Lokas et al.,submitted to MNRAs(2005)9.N.W.Evans et al.,Phys.Rev.D6*******(2004)10.D.E.McLaughlin,ApJ512L9(1999)11.MAGIC Dark Matter Working Group,J.Flix,Phd.Thesis(2005)。

暗物质_中学教育-中考

Dark Matter暗物质There is perhaps no current problem of greater importance to astrophysics and cosmology than that of 'dark matter'.也许再没有比‘暗物质'对天体物理学和宇宙论而言是现在更为重要的问题了。

The controversy, as the name implies, is centered around the notion that there may exist an enormous amount of matter in the Universe which cannot be detected from the light which it emits.争论,如名字暗示的那样,争论的焦点集中在宇宙可能存在不能够从它发出的光被探测到的一种巨大量的物质。

This is 'matter' which cannot be seen directly. So what makes us think that it exists at all? Its presence is inferred indirectly from the motions of astronomical objects, specifically stellar, galactic, and galaxy cluster/supercluster observations.这是不能够被直接看到的‘物质'。

因此使我们认为它究竟存在与否?它的存在是从天文学物体运动确定的恒星，银河及银河星团/超星系观察被间接的推断出来。

The basic principle is that if we measure velocities in some region, then there has to be enough mass there for gravity to stop all the objects flying apart. When such velocity measurements are done on large scales, it turns out that the amount of inferred mass is much more than can be explained by the luminous stuff. Hence we infer that there is dark matter in the Universe. There are many different pieces of evidence on different scales. And on the very largest scales, there may be enough to "close" the Universe, so that it will ultimately re-collapse in a Big Crunch.基本的原则是如果我们在一些地方测量速度,那么在那里必须有阻止所有物体飞离所需引力足够大的质量存在。

05-15英语一新题型整理版完美打印版

How does your reading proceed? Clearly, you try to comprehend, in the sense of identifying meanings for individual words and working out relationships between them, drawing on your implicit knowledge of English grammar.(41)________________. You begin to infer a context for the text, for instance, by making decisions about what kind of speech event is evolved. Who is making the utterance, to whom, when and where?The ways of reading indicated here are without doubt kinds of comprehension but they show comprehension to consist not just of passive assimilation but of active engagement in inference and problem-solving. You infer information you feel the writer has invited you to grasp by presenting you with specific evidence and clues. (42) ________________ Conceived in this way, comprehension will not follow exactly the same track for each reader. What is in question is not the retrieval of an absolute, fixed or ―true‖ meaning that can be read off and checked for accuracy, or some timeless relationship of the text to the world. (43) _____________Such background material inevitably reflects who we are. (44) _____________. This does not, however, make interpretation merely relative or even pointless. Precisely because readers from different historical periods, places and social experiences produce different but overlapping readings of the same words on the page---including for texts that engage with fundamental human concerns--- debates about texts can play an important role in social discussion of belief and values.How we read a given text also depends to some extent on our particular interest in reading it. (45) _____________. Such dimensions of reading suggest---as others introduced later in the book will also do--that we bring an implicit (often unacknowledged) agenda to any act of reading. It does not then necessarily follow that one kind of reading is fuller, more advanced or more worthwhile than another. Ideally, different minds of reading inform each other, and act as useful reference points for and counterbalances to one another. Together, they make up the reading component of your overall literacy, or relationship to your surrounding textual environment.[A] Are we studying that text and trying to respond in a way that fulfills the requirement of a given course? Reading it simply for pleasure? Skimming it for information? Ways of reading on a train or in bed are likely to differ considerably from reading in a seminar room.[B] Factors such as the place and period in which we are reading, our gender ethnicity, age and social class will encourage us towards certain interpretations but at the same time obscure or even close off others.[C] If you are unfamiliar with words or idioms, you guess at their meaning, using clues presented in the context. On the assumption that they will become relevant later, you make a mental note of discourse entities as well as possible links between them.[D]In effect, you try to reconstruct the likely meanings or effects that any given sentence, image or reference might have had: These might be the ones the author intended.[E] You make further inferences, for instance, about how the text may be significant to you, or about its validity—inferences that form the basis of a personal response for which the author will inevitably be far less responsible.[F] In plays, novels and narrative poems, characters speak as constructs created by the author, not necessarily as m outhpieces for the author’s own thoughts.[G]Rather, we ascribe meanings to texts on the basis of interaction between what we might call textual and contextual material: between kinds of organizations or patterning we perceive in a text’s formal structur es (so especially its language structures) and various kinds of background, social knowledge, belief and attitude that we bring to the text.[A] Some archaeological sites have always been easily observable—for example, the Parthenon in Athens, Greece; the pyramids of Giza in Egypt; and the megaliths of Stonehenge in southern England. But these sites are exceptions to the norm .Most archaeological sites have been located by means of careful searching, while many others have been discovered by accident. Olduvai Gorge, fell into its deep valley in 1911.Thousands of Aztec artifacts came to light during the digging of the Mexico City subway in the 1970s.[B] In another case, American archaeologists Rene million and George Cowgill spent years systematically mapping the entire city of Teotihuacan in the valley of Mexico near what is now Mexico City .at its peak around AD 600, this city was one of the largest human settlements in the word. The researchers mapped not only the city’s vast and ornate ceremo nial areas, but also hundreds of simpler apartment complexes where common people lived.[C] How do archaeologists know where to find what they are looking for when there is nothing visible on the surface of the ground? Typically, they survey and sample (make test excavations on) large areas of terrain to determine where excavation will yield useful information. Surveys and test samples have also become important for understanding the larger landscapes that contain archaeological sites.[D] Surveys can cover a single large settlement or entire landscapes. In one case, many researchers working around the ancient Maya city of Copán, Honduras, have located hundreds of small rural village and individual dwellings by using aerial photographs and by making surveys on foot. The resulting settlement maps show how the distribution and density of the rural population around the city changed dramatically between AD500 and 850, when Copán collapsed.[E] To find their sites, archaeologists today rely heavily on systematic survey methods and a variety of high-technology tools and techniques. Airborne technologies, such as different types of radar and photographic equipment carried by airplanes or spacecraft, allow archaeologists to learn about what lies beneath the ground without digging. Aerial surveys locate general areas of interest or larger buried features, such as ancient buildings or fields.[F] Most archaeological sites, however, are discovered by archaeologists who have set out to look for them. Such searches can take years. British archaeologist Howard Carter knew that the tomb of the Egyptian pharaoh Tutankhamen existed from information found in other sites. Carter sifted through rubble in the Valley of the King for seven years before he located the tomb in 1922. In the late 1800s British archaeologist Sir Arthur Eyan combed antique dealers’ stores in Athens, Greece. He was searching for thing engraved seals attributed to the ancient Mycenaean culture that dominated Greece from the 1400s to 1200s BC. Evas’s inter pretations of those engravings eventually led them to find the Minoan palace at Knossos on the island of Crete, in 1900.[G] Ground surveys allow archaeologists to pinpoint the places where digs will be successful. Most ground surveys involve a lot of walking, looking for surface clues such as small fragments of pottery. They often include a certain amounts of digging to test for buried materials at selected points across a landscape. Archaeologists also may locate buried remains by using such technologies as ground radar, magnetic-field recording, and metal detector. Archaeologists commonly use computers to map sites and the landscapes around sites. Two and three-dimensional maps are helpful tools in planning excavations, illustrating how sites look, and presenting the results of archaeological research.41 --- A --- 42. --- E ---43 --- 44 --- 45The social sciences are flourishing.As of 2005,there were almost half a million professional social scientists from all fields in the world, working both inside and outside academia. According to the World Social Science Report 2010,the number of social-science students worldwide has swollen by about 11% every year since 2000.Yet this enormous resource in not contributing enough to today’s globa l challenges including climate change, security,sustainable development and health.(41)______Humanity has the necessary agro-technological tools to eradicate hunger , from genetically engineered crops to arificial fertilizers . Here , too, the problems are social: the organization and distribution of food, wealth and prosperity.(42)____This is a shame—the community should be grasping the opportunity to raise its influence in the real world. To paraphrase the great social scientist Joseph Schumpeter:there is no radical innovation without creative destruction .Today ,the social sciences are largely focused on disciplinary problems and internal scholarly debates,rather than on topics with external impact.Analyses reveal that the number of papers including th e keywords ―environmental changed‖ or ―climate change‖ have increased rapidly since 2004,(43)____When social scientists do tackle practical issues ,their scope is often local:Belgium is interested mainly in the effects of poverty on Belgium for example .A nd whether the community’s work contributes much to an overall accumulation of knowledge is doubtful.The problem is not necessarily the amount of available funding (44)____this is an adequate amount so long as it is aimed in the right direction. Social sc ientists who complain about a lack of funding should not expect more in today’s economic climate.The trick is to direct these funds better.The European Union Framework funding programs have long had a category specifically targeted at social scientists.This year,it was proposed that system be changed:Horizon 2020,a new program to be enacted in 2014,would not have such a category ,This has resulted in protests from social scientists.But the intention is not to neglect social science ; rather ,the complete opposite.(45)____That should create more collaborative endeavors and help to develop projects aimed directly at solving global problems.[A] It could be that we are evolving two communities of social scientists:one that is discipline-oriented and publishing in highly specialized journals,and one that is problem-oriented and publishing elsewhere,such as policy briefs.[B] However,the numbers are still small:in 2010,about 1,600 of the 100,000 social-sciences papers published globally included one of these Keywords.[C] the idea is to force social to integrate their work with other categories, including health and demographic change food security, marine research and the bio-economy, clear, efficient energy; and inclusive, innovative and secure societies.[D] the solution is to change the mindset of the academic community, and what it considers to be its main goal. Global challenges and social innovation ought to receive much more attention from scientists, especially the young ones.[E] These issues all have root causes in human behavior . all require behavioral change and social innovations , as well as technological development . Stemming climate change , for example , is as much about changing consumption patterns and promoting tax acceptance as it is about developing clean energy.[F] Despite these factors , many social scientists seem reluctant to tackle such problems . And in Europe , some are up in arms over a proposal to drop a specific funding category for social-science research and to integrate it within cross-cutting topics of sustainable development .[G] During the late 1990s , national spending on social sciences and the humanities as a percentage of all research and development funds-including government, higher education, non-profit and corporate -varied from around 4% to 25%; inThink of those fleeting moments when you look out of an aeroplane window and realise that you are flying, higher than a bird. Now think of your laptop, thinner than a brown-paper envelope, or your cellphone in the palm of your hand. Take a moment or two to wonder at those marvels. You are the lucky inheritor of a dream come true.The second half of the 20th century saw a collection of geniuses, warriors, entrepreneurs and visionaries labour to create a fabulous machine that could function as a typewriter and printing press, studio and theatre, paintbrush and gallery, piano and radio, the mail as well as the mail carrier. (41)The networked computer is an amazing device, the first media machine that serves as the mode of production, means of distribution, site of reception, and place of praise and critique. The computer is the 21st century's culture machine.But for all the reasons there are to celebrate the computer, we must also tread with caution. (42)I call it a secret war for two reasons. First, most people do not realise that there are strong commercial agendas at work to keep them in passive consumption mode. Second, the majority of people who use networked computers to upload are not even aware of the significance of what they are doing.All animals download, but only a few upload. Beavers build dams and birds make nests. Yet for the most part, the animal kingdom moves through the world downloading. Humans are unique in their capacity to not only make tools but then turn around and use them to create superfluous material goods - paintings, sculpture and architecture - and superfluous experiences - music, literature, religion and philosophy. (43)For all the possibilities of our new culture machines, most people are still stuck in download mode. Even after the advent of widespread social media, a pyramid of production remains, with a small number of people uploading material, a slightly larger group commenting on or modifying that content, and a huge percentage remaining content to just consume.(44)Television is a one-way tap flowing into our homes. The hardest task that television asks of anyone is to turn the power off after he has turned it on.(45)What counts as meaningful uploading? My definition revolves around the concept of "stickiness" - creations and experiences to which others adhere.[A] Of course, it is precisely these superfluous things that define human culture and ultimately what it is to be human. Downloading and consuming culture requires great skills, but failing to move beyond downloading is to strip oneself of a defining constituent of humanity.[B] Applications like , which allow users to combine pictures, words and other media in creative ways and then share them, have the potential to add stickiness by amusing, entertaining and enlightening others.[C] Not only did they develop such a device but by the turn of the millennium they had also managed to embed it in a worldwide system accessed by billions of people every day.[D] This is because the networked computer has sparked a secret war between downloading and uploading - between passive consumption and active creation - whose outcome will shape our collective future in ways we can only begin to imagine.[E] The challenge the computer mounts to television thus bears little similarity to one format being replaced by another in the manner of record players being replaced by CD players.[F] One reason for the persistence of this pyramid of production is that for the past half-century, much of the world's media culture has been defined by a single medium - television - and television is defined by downloading.[G]The networked computer offers the first chance in 50 years to reverse the flow, to encourage thoughtful downloading[A] No disciplines have seized on professionalism with as much enthusiasm the humanities. You can, Mr. Menand points out, became a lawyer in three years and a medical doctor in four. But the regular time it takes to get a doctoral degree in the humanities is nine years. Not surprisingly, up to half of all doctoral students in English drop out before getting their degrees.[B] His concern is mainly with the humanities: Literature, languages, philosophy and so on. These are disciplines that are going out of sytle:22% of American college graduates now major in business compared with only 2% in history and 4% in English. However, many leading American universities want their undergraduates to have a grounding in the basic canon of ideas that every educated person should posses. But most find it difficult to agree on what a ―general education‖ should look like. At Harvard, Mr. Menand notes, ―the great books are read because they have been read‖, they form a sort of social glue.[C] Equally unsurprisingly, only about half end up with professorships for which they entered graduate school. There are simply too few posts. This is partly because universities continue to produce ever more PhDs. But fewer students want to study humanities subjects: English department awarded more bachelor’s degrees in 1970-71 than they did 20 years later. Fewer students requires fewer teachers. So, at the end of a decade of theses-writing, many humanities students leave the profession to du something for which they have not been trained.[D] One reason why it is hard to design and teach courses is that they can cut across the insistence by top American universities that liberal-arts educations and professional education should be kept separate, taught in different schools. Many students experience both varieties Although more than half of Harvard undergraduates end up in law, medicine or business, future doctors and lawyers must study a non-specialist liberal-art degree before embarking on a professional qualification.[E] Besides professionalizing the professions by this separation top American universities have professionalized the professor. The growth on public money for academic research has speeded the process: federal research grants rose fourfold between 1960 and 1990, but faculty teaching hours fell by half as research took its toll. Professionalism has turned the acquisition of a doctoral degree into a prerequisite for a successful academic career: as late as 1969 a third of American professors did not possess one. But the key idea behind professionalization, argues Mr. Menand, is that ―the knowledge and skills needed for a particular specialization are transmissible but not transferab le.‖ So disciplines acquire a monopoly not just over the production of knowledge, but also over the production of the producers of knowledge.[F] The key to reforming higher education, concludes Mr. Menand, is to alter the way in which ―the producers of k nowledge are produced.‖ Otherwise, academics will continue to think dangerously alike, increasingly detached from the societies which they study, investigate and criticize. ―Academic inquiry, at least in some fields, may need to become less exclusionary an d more holistic.‖ Yet quite how that happens, Mr. Menand dose not say.[G] The subtle and intelligent little book The marketplace of Ideas: Reform and Resistance in the American University should be read by every student thinking of applying to take a doctoral degree. They may then decide to go elsewhere. For something curious has been happening in American Universities, and Louis Menand, a professor of English at Harvard University, captured it skillfully.[A] The first and more important is the consumer's growing preference for eating out; the consumption of food and drink in places other than homes has risen from about 32 percent of total consumption in 1995 to 35 percent in 2000 and is expected to approach 38 percent by 2005. This development is boosting wholesale demand from the food service segment by 4 to 5 percent a year across Europe, compared with growth in retail demand of 1 to 2 percent. Meanwhile, as the recession is looming large, people are getting anxious. They tend to keep a tighter hold on their purse and consider eating at home a realistic alternative.[B] Retail sales of food and drink in Europe's largest markets are at a standstill, leaving European grocery retailers hungry for opportunities to grow. Most leading retailers have already tried e-commerce, with limited success, and expansion abroad. But almost all have ignored the big, profitable opportunity in their own backyard: the wholesale food and drink trade, which appears to be just the kind of market retailers need.[C] Will such variations bring about a change in the overall structure of the food and drink market? Definitely not. The functioning of the market is based on flexible trends dominated by potential buyers. In other words, it is up to the buyer, rather than the seller, to decide what to buy .At any rate, this change will ultimately be acclaimed by an ever-growing number of both domestic and international consumers, regardless of how long the current consumer pattern will take hold.[D] All in all, this clearly seems to be a market in which big retailers could profitably apply their scale, existing infrastructure and proven skills in the management of product ranges, logistics, and marketing intelligence. Retailers that master the intricacies of wholesaling in Europe may well expect to rake in substantial profits thereby. At least, that is how it looks as a whole. Closer inspection reveals important differences among the biggest national markets, especially in their customer segments and wholesale structures, as well as the competitive dynamics of individual food and drink categories. Big retailers must understand these differences before they can identify the segments of European wholesaling in which their particular abilities might unseat smaller but entrenched competitors. New skills and unfamiliar business models are needed too.[E] Despite variations in detail, wholesale markets in the countries that have been closely examined—France, Germany, Italy, and Spain—are made out of the same building blocks. Demand comes mainly from two sources: independent mom-and-pop grocery stores which, unlike large retail chains, are two small to buy straight from producers, and food service operators that cater to consumers when they don't eat at home. Such food service operators range from snack machines to large institutional catering ventures, but most of these businesses are known in the trade as "horeca": hotels, restaurants, and cafes. Overall, Europe's wholesale market for food and drink is growing at the same sluggish pace as the retail market, but the figures, when added together, mask two opposing trends.[F] For example, wholesale food and drink sales come to $268 billion in France, Germany, Italy, Spain, and the United Kingdom in 2000—more than 40 percent of retail sales. Moreover, average overall margins are higher in wholesale than in retail; wholesale demand from the food service sector is growing quickly as more Europeans eat out more often; and changes in the competitive dynamics of this fragmented industry are at last making it feasible for wholesalers to consolidate.[G] However, none of these requirements should deter large retailers (and even some large good producers and existing wholesalers) from trying their hand, for those that master the intricacies of wholesaling in Europe stand to reap considerable gains.Coinciding with the groundbreaking theory of biological evolution proposed by British naturalist Charles Darwin in the 1860s, British social philosopher Herbert Spencer put forward his own theory of biological and cultural evolution. Spencer argued that all worldly phenomena, including human societies, changed over time, advancing toward perfection.41.____________.American social scientist Lewis Henry Morgan introduced another theory of cultural evolution in the late 1800s. Morgan, along with Tylor, was one of the founders of modern anthropology. In his work, he attempted to show how all aspects of culture changed together in the evolution of societies.42._____________.In the early 1900s in North America, German-born American anthropologist Franz Boas developed a new theory of culture known as historical particularism. Historical particularism, which emphasized the uniqueness of all cultures, gave new direction to anthropology. 43._____________.Boas felt that the culture of any society must be understood as the result of a unique history and not as one of many cultures belonging to a broader evolutionary stage or type of culture. 44._______________.Historical particularism became a dominant approach to the study of culture in American anthropology, largely through the influence of many students of Boas. But a number of anthropologists in the early 1900s also rejected the particularist theory of culture in favor of diffusionism. Some attributed virtually every important cultural achievement to the inventions of a few, especially gifted peoples that, according to diffusionists, then spread to other cultures. 45.________________.Also in the early 1900s, French sociologist Émile Durkheim developed a theory of culture that would greatly influence anthropology. Durkheim proposed that religious beliefs functioned to reinforce social solidarity. An interest in the relationship between the function of society and culture—known as functionalism—became a major theme in European, and especially British, anthropology.[A] Other anthropologists believed that cultural innovations, such as inventions, had a single origin and passed from society to society. This theory was known as diffusionism.[B] In order to study particular cultures as completely as possible, Boas became skilled in linguistics, the study of languages, and in physical anthropology, the study of human biology and anatomy.[C] He argued that human evolution was characterized by a struggle he called the "survival of the fittest," in which weaker races and societies must eventually be replaced by stronger, more advanced races and societies.[D] They also focused on important rituals that appeared to preserve a people's social structure, such as initiation ceremonies that formally signify children's entrance into adulthood.[E] Thus, in his view, diverse aspects of culture, such as the structure of families, forms of marriage, categories of kinship, ownership of property, forms of government, technology, and systems of food production, all changed as societies evolved.[F] Supporters of the theory viewed as a collection of integrated parts that work together to keep a society functioning.[G] For example, British anthropologists Grafton Elliot Smith and W. J. Perry incorrectly suggested, on the basis of inadequate information, that farming, pottery making, and metallurgy all originated in ancient Egypt and diffused throughout the world. In fact, all of these cultural developments occurred separately at different times in many parts of the world.The time for sharpening pencils, arranging your desk, and doing almost anything else instead of writing has ended. The first draft will appear on the page only if you stop avoiding the inevitable and sit, stand up, or lie down to write. (41) Be flexible. Your outline should smoothly conduct you from one point to the next, but do not permit it to railroad you. If a relevant and important idea occurs to you now, work it into the draft. (42) Grammar, punctuation, and spelling can wait until you revise. Concentrate on what you are saying. Good writing most often occurs when you are in hot pursuit of an idea rather than in a nervous search for errors.(43) Your pages will be easier to keep track of that way, and, if you have to clip a paragraph to place it elsewhere, you will not lose any writing on the other side.If you are working on a word processor, you can take advantage of its capacity to make additions and deletions as well as move entire paragraphs by making just a few simple keyboard commands. Some software programs can also check spelling and certain grammatical elements in your writing. (44) These printouts are also easier to read than the screen when you work on revisions.Once you have a first draft on paper, you can delete material that is unrelated to your thesis and add material necessary to illustrate your points and make your paper convincing. The student who wrote ―The A & P as a State of Mind‖ wisely dropped a paragraph that questioned whether Sammy displays chauvinistic attitudes toward women. (45) Remember that your initial draft is only that. You should go through the paper many times – and then again – working to substantiate and clarify your ideas. You may even end up with several entire versions of the paper. Rewrite. The sentences within each paragraph should be related to a single topic. Transitions should connect one paragraph to the next so that there are no abrupt or confusing shifts. Awkward or wordy phrasing or unclear sentences and paragraphs should be mercilessly poked and prodded into shape.[A] To make revising easier, leave wide margins and extra space between lines so that you can easily add words, sentences, and corrections. Write on only one side of the paper.[B] After you have clearly and adequately developed the body of your paper, pay particular attention to the introductory and concluding paragraphs. It’s probably best to write the introduction last, after you know precisely what you are introducing. Concluding paragraphs demand equal attention because they leave the reader with a final impression.[C] It’s worth remembering, however, that though a clean copy fresh off a printer may look terrific, it will read only as well as the thinking and writing that have gone into it. Many writers prudently store their data on disks and print their pages each time they finish a draft to avoid losing any material because of power failures or other problems.[D] It makes no difference how you write, just so you do. Now that you have developed a topic into a tentative thesis, you can assemble your notes and begin to flesh out whatever outline you have made.[E] Although this is an interesting issue, it has nothing to do with the thesis, which explains how the setting influences Sammy’s decision to quit his job. Instead of including that paragraph, she added one that described Lengel’s crabbed response to the girls so that she could lead up to the A & P ―policy‖ he enforces.[F] In the final paragraph about the significan ce of the setting in ―A & P,‖ the student brings together the reasons Sammy quit his job by referring to his refusal to accept Lengel’s store policies.[G] By using the first draft as a means of thinking about what you want to say, you will very likely discover more than your notes originally suggested. Plenty of good writers don’t use outlines at all but discover ordering principles as they write. Do not attempt to compose a perfectly correct draft the first time around.。

Dark Matter in the Solar System

PACS numbers: 95.30.Sf, 95.35.+d, 96.50.Pw, 98.35.Gi, 98.80.-k
I.
INTRODUCTION
Accounting for about 23% of the energy density of the Universe [1], dark matter is an integral part of our surroundings. It dominates the more familiar, baryonic components, which comprises only 4.4% of the Universe, on the largest scales. Achieving an understanding of this perplexing dark element is one of the most compelling unsolved problems in modern astrophysics. The astrophysical evidence for the existence of dark matter is overwhelming, as observations of the cosmic microwave background [1], the power spectrum of the Universe [2], and colliding galaxy clusters [3] all point towards the same conclusion. With an understanding that a dark, pressureless, ﬂuid-like component permeates the Universe, astrophysicists have successfully simulated the large-scale processes of structure formation in the context of a ΛCDM Universe [4]. More recently, some attention has been given to the dark matter substructure formed on subgalactic scales, down to scales of order 10−2 pc [5]. However, relatively little consideration has been given to the distribution of dark matter within our own Solar System. Yet, dark matter may prove to be profoundly important in our Solar System for both its additional gravitational eﬀects on planets and other orbiting bodies [6, 7, 8] as well as the motions of spacecraft [9, 10]. Furthermore, a knowledge of the density and velocity of dark matter particles is particularly important for terrestrial direct detection experiments [11]. In this paper, we model the Solar System and the dark matter that it encounters in order to quantify how much dark matter we expect the Solar System to have captured over its lifetime. Through favorable three-body gravita-

暗物质英文介绍

Detection
Direct detection experiments
Indirect detection experiments
DETECTION
If the dark matter within our galaxy is made up of Weakly Interacting Massive Particles (WIMPs), then thousands of WIMPs must pass through every square centimeter of the Earth each second.[84][85] There are many experiments currently running, or planned, aiming to test this hypothesis by searching for WIMPs. Although WIMPs are the historically more popular dark matter candidate for searches,[9] there are experiments searching for other particle candidates; the Axion Dark Matter eXperiment (ADMX) is currently searching for the dark matter axion, a well-motivated and constrained dark matter source. It is also possible that dark matter consists of very heavy hidden sector particles which only interact with ordinary matter via gravity.

Investigating the Nature of Dark Matter

Investigating the Nature of DarkMatterThe phrase “dark matter” has become a buzzword in modern astrophysics as well as popular culture, and yet we still know very little about what dark matter really is. It is a mysterious substance that makes up 27% of the universe and that cannot be observed directly, but can only be inferred from the gravitational effects it has on visible matter. Therefore, dark matter is a topic of intense research and debate in the scientific community. In this article, we will explore the key aspects of dark matter and the different ways scientists are working to uncover its nature.What is Dark Matter?As mentioned, dark matter is a substance that does not emit, absorb or reflect light, hence its name. It does not interact strongly with electromagnetic forces, but it does with gravity, which is why its presence can be inferred from the gravitational effects it has on visible matter. One of the most well-known examples of this is the rotation curve of spiral galaxies. According to the laws of classical mechanics, the velocity of stars and gas in a galaxy should decrease as one moves away from the center, as the gravitational attraction of the visible matter decreases. However, observations have shown that the velocity remains constant or even increases, suggesting that there is an invisible mass that is causing this anomaly. This invisible mass is the dark matter.Another piece of evidence for the existence of dark matter is the distribution of matter in the universe as revealed by the cosmic microwave background radiation, which is the afterglow of the Big Bang. The pattern of temperature fluctuations in this radiation shows that the matter in the universe is not distributed evenly, but is rather clumped up in large structures such as galaxies and clusters of galaxies. However, this clumping up cannot be explained solely by the gravitational influence of visible matter; there must be an additional source of gravity, i.e. dark matter, to explain the observed distribution.Moreover, measurements of the large-scale structure of the universe, such as the distribution of galaxies and galaxy clusters, also point to the existence of dark matter.What is Dark Matter Made of?Despite its importance in shaping the structure of the universe, the identity of dark matter remains unknown. There are several hypotheses about what dark matter might be made of, but none of them has been conclusively proven yet. One popular hypothesis is that dark matter is composed of weakly interacting massive particles (WIMPs), which are hypothetical particles that would interact with normal matter only through the weak nuclear force and gravity. The idea is that WIMPs were produced in the early universe when it was hot and dense, and have been moving around freely ever since. If they collide with normal matter, they would transfer some of their energy and momentum, producing detectable signals. In fact, several experiments have been designed to detect WIMP interactions, such as the Large Underground Xenon (LUX) experiment and the Super Cryogenic Dark Matter Search (SuperCDMS).Another hypothesis is that dark matter is made of axions, which are theoretical particles that were originally proposed to explain a different problem in physics, the strong CP problem. The idea is that axions would be very light and weakly interacting, making them difficult to detect, but would still affect the motion of galaxies and other cosmic structures. The Axion Dark Matter eXperiment (ADMX) is currently searching for evidence of axions in a laboratory at the University of Washington.A third hypothesis is that dark matter is composed of primordial black holes, which are black holes that were formed by the collapse of a density fluctuation in the early universe. The idea is that these black holes could have a mass range that would make them more likely to be dark matter, and that their interactions with normal matter could produce observable effects. However, this hypothesis is less favored by most researchers, as the formation and stability of such black holes would require very specific conditions.ConclusionDespite decades of research, the nature of dark matter remains one of the most intriguing and elusive topics in astrophysics. It remains a theoretical construct that cannot be directly observed, but its effects on the motion and structure of the cosmos are undeniable. Researchers are continuing to study dark matter using a variety of tools and techniques, from telescopes that measure gravitational lensing to underground experiments that look for WIMP interactions. The hope is that someday we will finally be able to unravel the mystery of what dark matter is made of, and in doing so, gain a better understanding of the universe and our place in it.。

Dark Matter

Mass / Energy Density
Scientists have measured the density of the universe by studying clusters of galaxies. We can call it either mass density or energy density. Einstein proved that mass and energy are the same with his equation E = mc2. He’s also the guy to blame for this curved space-time stuff. (learn more)
But . . .
But outer stars do not rotate correctly! If gravity causes galaxies to rotate, as we assume it does, then outer stars should behave much like the planets of our solar system. Inner planets rotate faster and outer planets rotate slower. This is called Keplerian motion. (learn more) In galaxies, however, both inner and outer stars rotate at about the same speed.
The Universe
Cosmologists study the birth and death of the universe. They also study its properties including its shape. Recent observation indicate that the universe is flat.

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a r X i v :h e p -p h /0107151v 2 15 J u l 2001ACT-07/01,CTP-TAMU-24/01CERN-TH/2001-168,UA/NPPS-8-01HEPHY-PUB 741/01hep-ph/0107151Dark Matter Direct Searches and the Anomalous Magnetic Moment of Muon hanas 1, D.V.Nanopoulos 2and V.C.Spanos 31University of Athens,Physics Department,Nuclear and Particle Physics Section,GR–15771Athens,Greece 2Department of Physics,Texas A &M University,College Station,TX 77843-4242,USA,Astroparticle Physics Group,Houston Advanced Research Center (HARC),Mitchell Campus,Woodlands,TX 77381,USA,and Academy of Athens,Chair of Theoretical Physics,Division of Natural Sciences,28Panepistimiou Avenue,Athens 10679,Greece 3Institut f¨u r Hochenergiephysik der ¨Osterreichischen Akademie der Wissenschaften,A–1050Vienna,Austria AbstractIn the framework of the Constrained Minimal Supersymmetric Standard Model(CMSSM)we discuss the impact of the recent experimental information,especially from E821Brookhaven experiment on g µ−2along with the light Higgs boson mass bound from LEP,to the Dark Matter direct searches.Imposing these experimen-tal bounds,the maximum value of the spin-independent neutralino-nucleon cross section turns out to be of the order of 10−8pb for large values of tan βand low M 1/2,m 0.The eﬀect of the recent experimental bounds is to decrease the maxi-mum value of the cross section by about an order of magnitude,demanding the analogous sensitivity from the direct Dark Matter detection experiments.Supersymmetry,or fermion-boson symmetry,is an omnipotent and ubiquitous ele-ment in our eﬀorts to construct a uniﬁed theory of all fundamental interactions observed in nature.At very high energies,close to the Planck scale(M P)it is indispensable in con-structing consistent string theories,thus dubbed superstrings.At low energies(∼1TeV) it seems unavoidable if the gauge hierarchy problem is to be resolved.Such a resolution provides a measure of the supersymmetry breaking scale M SUSY≈O(1TeV).There is, albeit circumstantial or indirect,evidence for such a low-energy supersymmetry breaking scale,from the uniﬁcation of the gauge couplings[1]and from the apparent lightness of the Higgs boson as determined from precise electroweak measurements,mainly at LEP[2].Furthermore,such a low energy SUSY breaking scale is also favored cosmo-logically.As is well known,R-parity conserving SUSY models,contain in the sparticle spectrum a stable,neutral particle,identiﬁable with the lightest neutralino(˜χ),referred as the LSP[3].One can then readily show[3]that such a LSP with mass,as low-energy SUSY entails,in the100GeV−1TeV region,may indeed provide the right form and amount of the highly desirable astrophysically and cosmologically Dark Matter(DM). As times goes by,the experimental evidence for DM,from diﬀerent quarters,strengthens in such a way,that it has assumed a central role in the modern cosmology.The most recent evidence,coming from the observation of theﬁrst three acoustic peaks in the Cos-mic Microwave Background(CMB)radiation small angle(θ O(10)anisotropies[4], is of tantalizing importance.It is not only provides strong support to aﬂat(k=0 orΩ0=1),inﬂationary Universe,but it also gives an unprecedented determination of ΩM h20≈0.15±0.05,which taking into account the simultaneously determined baryon densityΩB h20≈0.02,and the rather minute neutrino density suggestsΩDM h20=0.13±0.05(1)One then is tempted to combine this recently determined DM density,assuming,as we do here,that it is all due to neutralini(i.e.ΩDM≡Ω˜χ),with other presentlyavailable constraints from particle physics,in order toﬁnd out what is the chances ofobserving,soon or in the near future,DM directly in the laboratory by elastic neutralino-nucleus scattering,from the energy deposition in the detectors[5].These particle physicsconstraints include the lower bound on the mass of the Higgs bosons(m h≥113.5GeV) provided by LEP[6],the allowed region for b→sγ,at95%CL range(2.33×10−4<B(b→sγ)<4.45×10−4)[7],and the recent results from the BNL E821experiment[8] on the anomalous magnetic moment of the muon(δαµ=43(16)×10−10),assuming,as we do here,that is all due(at the1or2σlevel)to low-energy supersymmetry.It should be stressed that the possibility of a rather sizeable positive contribution to gµ−2from low energy SUSY in the region of large tanβandµ>0where the b→sγconstraint weakens considerably,has been long strongly emphasized[9].It is amusing to notice, that in our previous analysis of the direct DM searches[10],done before the the BNL E821announcement,we had paid particular interest in the large tanβregion,since it provided the higher possible rates for direct DM detection!Similar results are presented in Ref.[11].Actually,as we have stressed for some time now[10,12],one way to get the “right”amount of the neutralino mass density(Ω˜χh20),even for relative high values of m0 and M1/2,is to move to the large tanβregion,because eﬃcient neutralino annihilation directly through A and H poles,occurs.The annihilation cross sections increase with tanβ:couplings A˜χ˜χand Aτ¯τ,Ab¯b increase,while m A decreases,thus one may also expect a rather appreciable increase in the elastic˜χ-nucleon cross section,as is indeed the case.It may turn out,if the BNL E821result is due to low energy SUSY,that the imposed lower bounds on m0,M1/2and lower bounds on tanβ[13–16]make the direct neutralino annihilation,through the A,H poles,the major mechanism for getting the right amount of DM[10,12,17],as well as as being consistent with all available constraints[13,16].Before presenting our results we shall give a brief account on the numerical analysis employed in this paper.This will be useful in comparing our results with those of other authors.In our analysis we use two-loop renormalization group equations(RGE),in theMS strong coupling constant at M Z,which we consider as input,is related toˆα3throughαs(M Z)=ˆα3(M Z)/(1−∆ˆα3).∆ˆα3represent the threshold corrections which aﬀect signiﬁcantly the value ofˆα3at M Z and hence,through RGE,its value at M GUT.The latter turns out to be diﬀerent fromˆα1,2(M GUT),reﬂecting the fact that gauge coupling uniﬁcation is impossible to implement in the constrained scenario with universal boundary conditionsfor the soft masses.For the determination of the gauge couplingsˆα1,2we use as inputs the electromagnetic coupling constant a0the value of the Fermi coupling constant G F, and the Z-boson mass M Z.From these we determine the weak mixing angle,through √ˆs2ˆc2=πα0/DR scheme the latter is related to a0throughˆα(M Z)=a0/(1−∆ˆαem),where∆ˆαem are the appropriate threshold corrections(see Ref.[18]).The input value of the strong coupling constant is taken within the experimental rangeαs(M Z)=0.1185±0.002.In running the RGE’s,as arbitrary parameters we take are as usual the soft SUSY breaking parameters m0,M1/2,A0the value of tanβand the sign of the Higgsino mixing parameterµ.The top and tau physical masses,M t,Mτ,as well as theMS RGE’s,using three-loop RGE’s for the strong coupling constant.We also include two-loop QED corrections,as well as two-loop contributions from the interference of the QCD and QED corrections.The runningDR in the usual way.From these we can extract the corresponding Yukawa couplings at M Z.We point out that the important QCD as well as the supersymmetric gluino,sbottom and chargino,stop corrections to the bottom mass are duly taken into account.For the determination of the top Yukawa coupling at M t we relate its pole and running masses taking into account all dominant radiative corrections.By running the RGE’s we can have the value of the top Yukawa coupling at M Z.The determination of the Higgs and Higgsino mixing parameters,m23andµ,is a more subtle issue.These are obtained by solving the minimization conditions with the one-loop corrected eﬀective potential with all particle contributions taken into account. Since large values of tanβcause large logarithmic corrections,invalidating perturbation expansion,we solve the minimization equations taking as reference scale the average stop scale Q˜t≃√m23(M Z),µ(M Z),whenever needed,can be found by solving the RGE’s having as initial conditions the values of these quantities at Q˜t.For the calculation of the lightest supersymmetric particle(LSP)relic abundance,we solve the Boltzmann equation numerically using the machinery outlined in Ref.[12].In this calculation the coannihilation eﬀects,in regions whereτR approaches in mass the LSP,which is a high purity Bino,are properly taken into account.Before embarking to analyse our numericalﬁndings it would be beneﬁcial to review the physical mechanism through which the scalar,i.e.spin-independent,˜χ-nucleon cross section(σscalar)is enhanced,to levels approaching the sensitivity of ongoing experiments. Theσscalar is enhanced in the region of the parameter space where tanβis large[10] 1.The dominant contribution to this regime is the Higgs boson exchange.For given inputs m0,M1/2,A0and the sign ofµ,Higgs masses decrease as tanβincreases.Hence the contribution of Higgs bosons to neutralino–quark elastic cross section becomes more important in the large tanβregime.Such a decrease in the mass is not suﬃcient by itself to increaseσscalar.The major role in this increase plays the coupling of the CP-even heavy Higgs whose coupling to d-quark is proportional to cosα1Enhancement ofσscalar is also possible in the context of the so-called focus point supersymmetry scenario[19],where m0>1.5TeV,yet such large values of m0are not favourable by the recent gµ−2 data.is less suppressive,and the increase of the˜χ˜χA as well as the Ab¯b and Aτ¯τcouplings. The smallness of the LSP’s Higgsino component is compensated by the largeness of tanβyielding neutralino annihilation cross sections compatible with the recent astrophysical data.Hence there are regions in which we can obtain both low relic densities and high σscalar.Bearing all these in mind,we proceed discussing ourﬁndings.For our numerical analysis a large random sample of45,000points in the region of the parameter space designed by2<tanβ<55,M1/2<1.5TeV,m0<1.5TeV,|A0|<1TeV,andµ>0is used.Theµ<0case is not favored by the recent b→sγdata,as well as by the observed discrepancy of the gµ−2,if the latter is attributed to supersymmetry,and therefore we shall not discuss it in the sequel.It is also worth noticing that in theµ>0 case the constraint from b→sγdata is superseded by the m h>113.5GeV bound, in the bulk of the parameter space[13].Inﬁgure1we plot the scalar˜χ-nucleon cross section as function of the LSP mass,m˜χ.On the top of theﬁgure the shaded region(in cyan colour)is excluded by the CDMS experiment[20].The DAMA sensitivity region (coloured in yellow)is also plotted[21].Pluses(+)(in blue colour)represent points=(43.0±16.0)×10−10and the which are both compatible with the E821dataαSUSYµcosmological bounds for the neutralino relic densityΩ˜χh20=0.13±0.05.Diamonds (⋄)(in green colour)are points which are cosmologically acceptable with respect to thehas been relaxed to its2σregion,namely aforesaid bounds,but the bound to theαSUSYµ11<αSUSYµ×1010<75.The crosses(×)(in red colour)represent the rest of the points of our random sample.Here the Higgs boson mass bound,m h>113.5GeV has been properly taken into account.From thisﬁgure it is seen that the the points which are compatible both the gµ−2E821and the cosmological data(crosses)yield cross sections of the order of10−8−10−9pb and the maximum value of the m˜χis about200GeV.If one considers the2σregion of the gµ−2bound the preferred cross sections can be as small as10−10pb and correspondingly the upper bound of m˜χis drifted up to350GeV. In the followingﬁgures2and3theσscalar is plotted as function of the parameters m0 and tanβrespectively.One can see that the points which conform to cosmological and 1σgµ−2experimental constraints,yield a maximum value of m0about600GeV,and for the2σcase1200GeV.The aforementioned bounds on the m˜χand m0are relatedwith the analogous bounds put on the soft parameter M1/2and m0from the gµ−2E821 data[13,14,16].Fromﬁgure3it is apparent that the majority of the points that are compatible with cosmological and gµ−2data are accumulated toward rather large values of tanβ, speciﬁcally tanβ>40,although there are indeed few of them with smaller values of tanβ. As it has been already pointed out in the large tanβregion we can have simultaneously cosmologically acceptable values ofΩ˜χh20and also big values for the elastic cross section˜χ-nucleon.Furthermore the gµ−2muon data prefer large values of tanβ,asαSUSYµis proportional to tanβ[9].Therefore as tanβincreases large regions of the parameter space(m0,M1/2)are compatible with the E821experimental constraints.Taking all these into account it is not surprising that the conjunction of the cosmological and gµ−2data happens for large values of the tanβand for large scalar cross section˜χ-nucleon,as it can be perceived fromﬁgure3.Comparingﬁgure1and4one can realise how gµ−2data constrain m˜χmass to be up to200GeV or350GeV for the1σor2σcase respectively.Inﬁgure4we don’t impose the constraints stemming from gµ−2data,therefore due to the coannihilation processes the cosmologically acceptable LSP mass can be heavier than500GeV.What is also important to be noticed about the direct searches of DM is that imposing the gµ−2data the lowest allowed˜χ-nucleon cross section increased by about2orders of magnitude,from10−11pb to10−9pb.This fact is very encouraging for the future DM direct detection experiments.Figure5illustrates the signiﬁcance of the Higgs boson mass bound.If one allows for values m h>100GeV many points which yielding cross sections even O(10−7)pb paringﬁgure1and5we observe that the recent Higgs mass bound(m h>113.5GeV)reduces the maximum value of the scalar cross section for about one order of magnitude,that is from10−7pb to10−8pb.There is direct and indirect dependence of theσscalar on m h.As m h decreases its contribution to theσscalar,being proportional to1/m h,increases leading to largerσscalar.The indirect relation of theσscalar to m h can be perceived from Eq.2.Light m h results to light m H and therefore to largeσscalar again.Concluding we have studied the impact of the recent experimental information to the DM direct searches.Especially we have considered the eﬀect of the recently reporteddeviation of gµ−2from its SM value,as well as of the light Higgs boson mass bound from LEP experiments.The imposition of these experimental constraints results to a maximum value for the spin-independent˜χ-nucleon cross section of the order of10−8 pb for m˜χ∼100GeV as small as allowed by chargino searches,and for tanβ>45as large as possible for the Higgs states to be as light as allowed by theoretical constraints and experimental searches.As it can be seen fromﬁgures4and5the eﬀect of these experimental constraints is to decrease the maximum value ofσscalar by almost one order of magnitude,and therefore to make the direct detection of the LSP on the future experiments by some means more diﬃcult.AcknowledgementsA.B.L.acknowledges support from HPRN-CT-2000-00148and HPRN-CT-2000-00149 programmes.He also thanks the University of Athens Research Committee for partially supporting this work.D.V.N.acknowledges support by D.O.E.grant DE-FG03-95-ER-40917and thanks the CERN Theory Division for hospitality during the completion of this work.V.C.S.acknowledges support by a Marie Curie Fellowship of the EU programme IHP under contract HPMFCT-2000-00675.References[1]J.Ellis,S.Kelley and D.V.Nanopoulos,Phys.Lett.B260(1991)131;U.Amaldi,W.de Boer and H.Furstenau,Phys.Lett.B260(1991)447;C.Giunti,C.W.Kim and U.W.Lee,Mod.Phys.Lett.A6(1991)1745.[2]LEP Electroweak Working Group,http://lepewwg.web.cern.ch/LEPEWWG/Welcome.html.[3]J.Ellis,J.S.Hagelin,D.V.Nanopoulos,K.A.Olive and M.Srednicki,Nucl.Phys.B238(1984)453;H.Goldberg,Phys.Rev.Lett.50(1983)1419.[4]A.T.Lee et.al.,MAXIMA Collaboration,astro-ph/0104459;terﬁeld et.al.,BOOMERANG Collaboration,astro-ph/0104460;N.W.Halverson et.al.,DASI Collaboration,astro-ph/0104489;P.de Bernardis et.al.,astro-ph/0105296.[5]M.W.Goodman and E.Witten,Phys.Rev.D31(1985)3059.[6]“Searches for the Neutral Higgs Bosons of the MSSM:Preliminary Com-bined Results Using LEP Data Collected at Energies up to209GeV”,The ALEPH,DELPHI,L3and OPAL 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Points are as in Fig.1.Figure3:In thisﬁgure we display the scalar neutralino-nucleon cross section versus tanβ.Points are as in Fig.1.Figure4:Scatter plot of the scalar neutralino-nucleon cross section versus m˜χ,from a random sample of Fig.1.Diamonds(⋄)are cosmologically acceptable points,withoutputting an restriction from theαSUSYµ.Crosses(×)represent points with unacceptableΩ˜χh20.Figure5:Scalar neutralino-nucleon cross section versus m˜χ.Points are as in Fig.1. Here the Higgs boson mass bound(m h>113.5GeV)has been relaxed and the bound m h>100GeV is used.。