Nonthermal Production of Weakly Interacting Massive Particles and the Subgalactic Structure of the Universe

Lin, Wenbin; Huang, De; Zhang, X.; Brandenberger, Robert H.

doi:10.1103/physrevlett.86.954

Cited by 159 publications

(138 citation statements)

References 30 publications

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“…14 we show In scenarios in which basically all dark matter consists of gravitinos from NLSP decays (f ≈ 1)-also known as superWIMP gravitino dark matter scenarios [17,18,21]-the warm dark matter limits from Table 1 can be applied [60]. Accordingly, Fig.…”

Section: Free Streaming Of Gravitinos and Constraints From Small-scalmentioning

confidence: 91%

Gravitino dark matter and cosmological constraints

Steffen¹

2006

J. Cosmol. Astropart. Phys.

171

147

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The gravitino is a promising candidate for cold dark matter. We study cosmological constraints on scenarios in which the gravitino is the lightest supersymmetric particle and a charged slepton the next-to-lightest supersymmetric particle (NLSP). We obtain new results for the hadronic nucleosynthesis bounds by computing the 4-body decay of the NLSP slepton into the gravitino, the associated lepton, and a quark-antiquark pair. The bounds from the observed dark matter density are refined by taking into account gravitinos from both late NLSP decays and thermal scattering in the early Universe. We examine the present free-streaming velocity of gravitino dark matter and the limits from observations and simulations of cosmic structures. Assuming that the NLSP sleptons freeze out with a thermal abundance before their decay, we derive new bounds on the slepton and gravitino masses. The implications of the constraints for cosmology and collider phenomenology are discussed and the potential insights from future experiments are outlined. We propose a set of benchmark scenarios with gravitino dark matter and long-lived charged NLSP sleptons and describe prospects for the Large Hadron Collider and the International Linear Collider.

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Section: Free Streaming Of Gravitinos and Constraints From Small-scalmentioning

confidence: 91%

Gravitino dark matter and cosmological constraints

Steffen¹

2006

J. Cosmol. Astropart. Phys.

171

147

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“…Another possible discrepancy is that the prediction of simulations for mass profile of CDM halos is excessively cuspy compared with observations, which is known as the cusp problem [79]. One of the resolutions to these problems is to invoke some DM whose free-streaming scale is in the range of O(0.1 − 1) Mpc, because it can sweep out density fluctuations in the small scale [80]. Then the axino LSP of our model may also be able to solve these problems.…”

Section: If the Wino Is Nlspmentioning

confidence: 99%

Axionic mirage mediation

2008

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Although the mirage mediation is one of the most plausible mediation mechanisms of supersymmetry breaking, it suffers from two crucial problems. One is the µ-/Bµ-problem and the second is the cosmological one. The former stems from the fact that the B parameter tends to be comparable with the gravitino mass, which is two order of magnitude larger than the other soft masses. The latter problem is caused by the decay of the modulus whose branching ratio into the gravitino pair is sizable. In this paper, we propose a model of mirage mediation, in which Peccei-Quinn symmetry is incorporated. In this axionic mirage mediation, it is shown that the Peccei-Quinn symmetry breaking scale is dynamically determined around 10 10 GeV to 10 12 GeV due to the supersymmetry breaking effects, and the µ-problem can be solved naturally. Furthermore, in our model, the lightest supersymmetric particle (LSP) is the axino, that is the superpartner of the axion. The overabundance of the LSPs due to decays of modulus/gravitino, which is the most serious cosmological difficulty in the mirage mediation, can be avoided if the axino is sufficiently light. The next-LSPs (NLSPs) produced by the gravitino decay eventually decay into the axino LSPs, yielding the dominant component of the axinos remaining today. It is shown that the axino with the mass of O(100) MeV is naturally realized, which can constitute the dark matter of the Universe, with the free-streaming length of the order of 0.1 Mpc. The saxion, the real scalar component of the axion supermultiplet, can also be cosmologically harmless due to the dilution of the modulus decay. The lifetime of NLSP is relatively long, but much shorter than 1 sec., when the big-bang nucleosynthesis commences. The decay of NLSP would provide intriguing collider signatures.

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“…(This is in spite of the fact that some of the problematic claims are disputed [11,12,13,14,15].) Solutions to the problems range from those that use baryonic physics [12,16,17,18,19,20] to those that rely on altering the nature of the dark matter [21,22,23,24,25]. While the astrophysical solutions are reasonably wellmotivated, the fact that problems seem to exist for relatively small, dark matter-dominated dwarf galaxies all the way to large ellipticals suggests that a single baryonic solution may not be able to address all of our concerns.…”

Section: Introductionmentioning

confidence: 99%

Inflation, cold dark matter, and the central density problem

2002

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The lingering problem with high central densities in dark halos has arisen in the context of (L)CDM cosmologies with n = 1 scale-invariant initial power spectra. Although n = 1 is often justified by appealing to the inflation scenario, the choice is not generally justified. Specifically, inflation models with mild but important deviations from scale invariance (n ∼ 0.9) are not uncommon, and those with significant "running" of the spectral index are quite plausible. Even a mild deviation from scale invariance can be important because halo collapse times and densities depend on the relative amount of small-scale power. Here, we choose several popular, often well-motivated, models of inflation and work out the ramifications for galaxy central densities. For each model, we calculate its COBE-normalized primordial power spectrum and deduce the implied halo densities using a semi-analytic method calibrated against N-body simulations. We compare our predictions to a sample of ∼ 50 dark matter-dominated galaxies using a non-parametric measure of the density, ∆ V/2 , defined as the mean mass density, relative to the critical density, within the radius at which the rotation curve falls to half of its maximum value. While standard n = 1 LCDM halos are overdense by a factor of ∼ 6, several of our example inflation+CDM models predict halo densities well within, and even below, the range preferred by observations. We also show how the presence of massive (mν ∼ 0.5 eV) neutrinos can help to alleviate the central density problem, even with a scale invariant spectrum. We conclude that galaxy central densities may not be as problematic for the CDM paradigm as is sometimes assumed: rather than telling us something about the nature of dark matter, galaxy rotation curves may be telling us something about inflation and/or neutrinos. An important test of this idea will be an eventual consensus on the value of σ8, the rms overdensity on the scale 8h −1 Mpc. Our successful models tend to have values of σ8 ≈ 0.75, which is well within the range of recent determinations. Finally, models with n > 1 (or σ8 > ∼ 1) are highly disfavored.

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Nonthermal Production of Weakly Interacting Massive Particles and the Subgalactic Structure of the Universe

Cited by 159 publications

References 30 publications

Gravitino dark matter and cosmological constraints

Gravitino dark matter and cosmological constraints

Axionic mirage mediation

Inflation, cold dark matter, and the central density problem

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