Dark Matter Theory
نویسنده
چکیده
We summarize the status of Dark Matter, focussing on recent developments, mostly prompted by the cosmic-ray excess observed by PAMELA and FERMI. Cosmology and astrophysics established that DM exists, but so far could see DM only via its gravitational interactions, weighting the total DM amount: Ω DM h 2 = 0.110 ± 0.005 [1]. This is all the positive information we have so far on DM. Various bounds tell that anything that behaves as collision-less dust can be DM: from an oscillating ultra-light scalar to a neutral new particle. In the latter case the DM cosmological abundance could be determined by thermal freeze-out within standard big-bang: in such a case the observed DM abundance is reproduced for a well defined value of the DM annihilation cross section: σ v ≈ 1 T now M Pl ≈ 3 · 10 −26 cm 3 sec = 0.0025 TeV 2 at velocity v ∼ 0.2 (1.1) where numerical values include order one factors. This σ v is typical of weak scale particles. If DM is the relic of a weak scale particle, we can soon discover in the following three ways: DM DM SM SM indirect and cosmology? ? DM SM DM SM direct ? SM SM DM DM collider ? i.e. i) we hope to see end-products of astrophysical DM annihilations in cosmic rays; ii) we hope to see DM scattering on normal matter; iii) we hope to produce DM at LHC. As we have no idea of which SM particle is involved in DM couplings, we do not know which search is better. In the next sections we summarize the various possibilities. 2. Cosmology and colliders Eq. (1.1) suggests DM at the weak scale: the key question is if DM is expected to be light enough to be produced at the LHC. As a typical cross section is σ ∼ g 4 /4πM 2 , heavier DM masses are obtained for larger DM couplings g. Many theories of Dark Matter, such as the MSSM, are compatible with a wide range of DM couplings, and consequently with a wide range of DM masses M. In order to predict M, we need to predict g: we assume that DM fills one weak multiplet that only has gauge interactions [13]. The following table shows in the few main cases the predicted 2 Dark Matter Theory Alessandro Strumia DM masses (taking into account co-annihilations and …
منابع مشابه
Singlet scalar dark matter in noncommutative space
In this paper, we examine the singlet scalar dark matter annihilation to becoming the Standard Model particles in the non-commutative space. In the recent decades, many candidates of dark matter have been offered, but our information about the nature of dark matter is still limited. There are such particle candidates as scalar matetr, fermion, boson, gauge boson, etc.; however, they have nei...
متن کاملHow Cold Dark Matter Theory Explains Milgrom’s Law
Milgrom noticed the remarkable fact that the gravitational effect of dark matter in galaxies only becomes important where accelerations are less than about 10 cm/s ∼ cH0 (“Milgrom’s Law”). This forms the basis for Modified Newtonian Dynamics (MOND), an alternative to particle dark matter. However, any successful theory of galactic dynamics must account for Milgrom’s Law. We show how Milgrom’s L...
متن کاملEddington-Born-Infeld action for dark energy and dark matter
We argue that Einstein gravity coupled to a Born-Infeld theory provides an attractive candidate to represent dark matter and dark energy. For cosmological models, the BornInfeld field has an equation of state which interpolates between matter, ω = 0 (small times), and a cosmological constant ω = −1 (large times). On galactic scales, the BornInfeld theory predicts asymptotically flat rotation cu...
متن کاملA Dark Matter Candidate With New Strong Interactions
We study the possibility that dark matter is a baryon of a new strongly interacting gauge theory, which was introduced in the low energy theory of Cosmological SUSY Breaking (CSB). This particle can fit the observed dark matter density if an appropriate cosmological asymmetry is generated. The same mechanism can also explain the dark/baryonic matter ratio in the universe. The mass of the dark m...
متن کاملA Born-Infeld action for dark energy and dark matter
We argue that Einstein gravity coupled to a Born-Infeld theory provides an attractive candidate to represent dark matter and dark energy. For cosmological models, the BornInfeld field has an equation of state which interpolates between matter, p = 0 (small times), and a cosmological constant p = −ρ (large times). On galactic scales, the BornInfeld theory predicts asymptotically flat rotation cu...
متن کاملFormation of Large Structures in the Acceleration Universe with a Hybrid Expansion Law
In the current paper, we have studied the effect of dark energy on for-mation where dark energy exists in the background. For this purpose, we used both WMAP9 and Planck data to study how the radius changes with redshift in these mod-els. We used different data sets to fix the cosmological parameters to obtain a solution for a spherical region under collapse. The mechanism of structure formation f...
متن کامل