No abstract

If dark matter (DM) is a weakly interacting massive particle (WIMP) that is a thermal relic of the early Universe, then its total self-annihilation cross section is revealed by its present-day mass density. This result for a generic WIMP is usually stated as σv ≈ 3 × 10 −26 cm 3 s −1 , with unspecified uncertainty, and taken to be independent of WIMP mass. Recent searches for annihilation products of DM annihilation have just reached the sensitivity to exclude this canonical cross section for 100 % branching ratio to certain final states and small WIMP masses. The ultimate goal is to probe all kinematically allowed final states as a function of mass and, if all states are adequately excluded, set a lower limit to the WIMP mass. Probing the low-mass region is further motivated due to recent hints for a light WIMP in direct and indirect searches. We revisit the thermal relic abundance calculation for a generic WIMP and show that the required cross section can be calculated precisely. It varies significantly with mass at masses below 10 GeV, reaching a maximum of 5.2 × 10 −26 cm 3 s −1 at m ≈ 0.3 GeV, and is 2.2 × 10 −26 cm 3 s −1 with feeble mass-dependence for masses above 10 GeV. These results, which differ significantly from the canonical value and have not been taken into account in searches for annihilation products from generic WIMPs, have a noticeable impact on the interpretation of present limits from Fermi-LAT and WMAP+ACT.

Primordial nucleosynthesis provides a probe of the Universe during its early evolution. Given the progress exploring the constituents, structure, and recent evolution of the Universe, it is timely to review the status of Big Bang Nucleosynthesis (BBN) and to confront its predictions, along with the constraints which emerge from them, with those derived from independent observations of the Universe at much later epochs in its evolution. Following an overview of the key physics controlling element synthesis in the early Universe, the predictions of BBN in the standard models of cosmology and particle physics are presented, along with those from some non-standard models. The observational data used to infer the primordial abundances are described, with an emphasis on the distinction between precision and accuracy. The observationally inferred relic abundances are compared with the predicted abundances, testing the internal consistency of BBN and enabling a comparison of the BBN-inferred constraints with those derived from the Cosmic Background Radiation and Large Scale Structure data. Emerging from these comparisons is confirmation of a successful standard model along with constraints on (or hints of) physics beyond the standard models of particle physics and of cosmology.Comment: Recently published article in the 2007 volume of the Annual Reviews of Nuclear and Particle Science (Vol. 57, p. 463-491). 13 Figures. Note that there are typos in eq.6 (2.68 should be 2.67) and in eq.26 (there should be a + sign in front of 106...

We review the Cosmology and Physics underlying Primordial Nucleosynthesis and survey current observational data in order to compare the predictions of Big Bang Nucleosynthesis with the inferred primordial abundances. From this comparison we report on the status of the consistency of the standard hot big bang model, we constrain the universal density of baryons (nucleons), and we set limits to the numbers and/or effective interactions of hypothetical new "light" particles (equivalent massless neutrinos).

Considerations of the age and density of, as weil as the evolution of structure in, the Universe lead to constraints on the masses and lifetimes of weakly interacting massive particles (WIMPS). L_ introduction TO date. much proqrerr ha* bee" made i" 'O"TWdl"i".q tne masses and ab~llddme5 (related to [he intrrdCtlOn rtrenglhr) of itdOte or long-llvaa 3drflCleT tlirwq" ihr reo"iI'emrnt tnat Lnrlr prerent oais urnrity not ercee t"dL Gbserved :see. e.g., rri. ill). amtmie relIcI *no,e decay Producti inClYde photoni d"d,Oi ,?leCtrlCally cnargeo pdrilclel. hdW tne>r iifetmer. 35 Ml, d$ their mdsies ana ab""dd"Cer. CO"itrai"dd dlrrctl, by *b~~r"aflon* of the background ~ad3dL1on fields (see. e.g.. ref. [Zjj ano. indirectly by i""Slderdtio", "f Itelldr ILrYilUre and WolYtl"". (see. e.g.. ref. ill) a,10 by plimordldl nuclearynrnerlr (see. e.g.. ref. [Oj,. IL tnignt irrm L"at ""stable particles whore decay QrOdUCrr ,nteract only feetsly (i.e.. particiwte in interaCtions 4liCh are as *l?ak. or weaker Gun. the "e*X IllleracLlo", night haYe disappeared WIthout a trace. I%*eYer. sucn pdrtlcles dnd ttle,r invisIble "ecdy prOdUCti may hd"E at one t>m dominated me energy dens,t/ "f the "niverre am. therefore. CLmtrOllea the rYOi"tion Of the llniverir 3urtng 1 Cnxidl epocn. I" a natUral eltenPi0" Uf pre"lO"I andlyres we use tne re""lremenfr Lhdt tnr present lllliwrir be ne>tner too young (UT, r""i"llC"Tly too aenie) 2nd that ftw oDl~r"ed large ica,e ItrUcTYre Should nave been air t" <""I".? i" ,r LO ilrrl"r :onstrsints *n the malses. JD"noa"Ce~ md llfetlmrr "f u"lLdblr. wea*1y I"ceraCt,"g marrive pdrticles (WIMPI) *h*Sc? deCdY DrDdYCii dr'e qinYiiihle" i1.e. inteidctionlesr) and ruifi'irntly IIqnt 10 tnal F"r dlI ~""Ch5 Of Interelt.they are uitr,rei,tlrlitlc.

No abstract

No abstract

No abstract