116970388
Dynamical Dark Matter and the positron excess in light of AMS results
The AMS-02 experiment has recently released data which confirms a rise in the cosmic-ray positron fraction as a function of energy up to approximately 350 GeV. Over the past decade, attempts to interpret this positron excess in terms of dark-matter decays have become increasingly complex and have led to a number of general expectations about the decaying dark-matter particles: such particles cannot undergo simple two-body decays to leptons, for example, and they must have rather heavy TeV-scale masses. In this paper, by contrast, we show that Dynamical Dark Matter (DDM) can not only match existing AMS-02 data on the positron excess, but also accomplish this feat with significantly lighter dark-matter constituents undergoing simple two-body decays to leptons. Moreover, we demonstrate that this can be done without running afoul of numerous other competing constraints from FERMI and Planck on decaying dark matter. Finally, we demonstrate that the Dynamical Dark Matter framework makes a fairly robust prediction that the positron fraction should level off and then remain roughly constant out to approximately 1 TeV, without experiencing any sharp downturns. Indeed, if we interpret the positron excess in terms of decaying dark matter, we find that the existence of a plateau in the positron fraction at energies less than 1 TeV may be taken as a "smoking gun" of Dynamical Dark Matter.
118483875
Gamma rays from bino-like dark matter in the MSSM
We consider regions of the parameter space of the Minimal Supersymmetric Standard Model (MSSM) with bino-like neutralino dark matter in which a large fraction of the total dark matter annihilation cross section in the present era arises from annihilation to final states with monoenergetic photons. The region of interest is characterized by light sleptons and heavy squarks. We find that it is possible for the branching fraction to final states with monoenergetic photons to be comparable to that for continuum photons, but in those cases the total cross section will be so small that it is unlikely to be observable. For models where dark matter annihilation may be observable in the present era, the branching fraction to final states with monoenergetic photons is O(1-10%).
118386561
Local scale-dependent non-gaussian curvature perturbations at cubic order
We calculate non-Gaussianities in the bispectrum and trispectrum arising from the cubic term in the local expansion of the scalar curvature perturbation. We compute to three-loop order and for general momenta. A procedure for evaluating the leading behavior of the resulting loop-integrals is developed and discussed. Finally, we survey unique non-linear signals which could arise from the cubic term in the squeezed limit. In particular, it is shown that loop corrections can cause fNLsq. to change sign as the momentum scale is varied. There also exists a momentum limit where τNL < 0 can be realized.
119200596
From DAMA/LIBRA To Super-Kamiokande
We consider the prospects for probing low-mass dark matter with the Super-Kamiokande experiment. We show that upcoming analyses including fully-contained events with sensitivity to dark matter masses from 5 to 10 GeV can test the dark matter interpretation of the DAMA/LIBRA signal. We consider prospects of this analysis for two light dark matter candidates: neutralinos and WIMPless dark matter.
119283275
Constraints on bosonic dark matter from observation of old neutron stars
Baryon interactions with bosonic dark matter are constrained by the potential for dark matter-rich neutron stars to collapse into black holes. We consider the effect of dark matter self-interactions and dark matter annihilation on these bounds, and treat the evolution of the black hole after formation. We show that, for non-annihilating dark matter, these bounds extend up to $m_X \sim 10^{5-7}$ GeV, depending on the strength of self-interactions. However, these bounds are completely unconstraining for annihilating bosonic dark matter with an annihilation cross-section of $ \gtrsim 10^{-38} {\rm cm^3 /s}$. Dark matter decay does not significantly affect these bounds. We thus show that bosonic dark matter accessible to near-future direct detection experiments must participate in an annihilation or self-interaction process to avoid black hole collapse constraints from very old neutron stars.
17960822
Raiders of the lost AdS
We demonstrate that under certain conditions a theory of conformal quantum mechanics will exhibit the symmetries of two half-Virasoro algebras. We further demonstrate the conditions under which these algebras combine to form a single-Virasoro algebra, and comment on the connection between this result and the AdS2/CFT1 correspondence.
120729664
A Class of Well Behaved Charged Analogues of Schwarzchild’s Interior Solution
A class of well behaved charged analogues of Schwarzchild’s interior solution has been obtained using a particular electric intensity. The solutions of this class are utilized to depict a superdense star model with surface density 2×1014 g cm−3. The solution obtained is new and the pressure (p), density (c2ρ), velocity of sound $(\sqrt{( dp / c^{2}d\rho )} )$ and (p/(c2ρ)) are monotonically decreasing towards the pressure free interface. Moreover the adiabatic constant is found to be more than (4/3) which is necessary for stability under radial perturbation. Also the electric intensity increases monotonically towards the surface. The well behaved model has the maximum mass M=1.740793MΘ, Radius 12.130308 km. The redshift at the center and on the surface is given by z0=0.384261 and za=0.292489. Out of the models of superdense star obtained couple of models represent Vela Pulsar for (i) α2=1.03, b=0.33, $\frac{a^{2}}{R^{2}} = 0.15$, Radius=10.8566 km, M=1.18331MΘ, I=0.642601×1045, (ii) α2=1.1, b=0.3, $\frac{a^{2}}{R^{2}} = 0.16$, Radius=11.197533 km, M=1.311438MΘ, I=0.774508×1045. All the solutions mentioned above are reducible to Schwarzchild interior solution in the absence of charge.