Modern Physics Letters A

Direct detection experiments are poised to detect dark matter in the form of weakly interacting massive particles (WIMPs). The signals expected in these experiments depend on the ultra-local WIMP density and velocity distribution. Firstly we review methods for modeling the dark matter distribution. We then discuss observational determinations of the local dark matter density, circular speed and escape speed, and the results of numerical simulations of Milky Way-like dark matter halos. In each case we highlight the uncertainties and assumptions made. We then overview the resulting uncertainties in the signals expected in direct detection experiments, specifically the energy, time and direction dependence of the event rate. Finally we conclude by discussing techniques for handling the astrophysical uncertainties when interpreting data from direct detection experiments.

A mean-field potential version of the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) model is used to investigate the production of strange (anti-)baryons, especially the Λs and s, from heavy ion collisions at SPS energies. It is found that, with the consideration of both formed and pre-formed hadron potentials in UrQMD, the transverse mass and longitudinal rapidity distributions of experimental data of both Λs and s can be quantitatively explained fairly well. Our investigation also shows the equal importance of both the production mechanism and the rescattering process of hadrons for the final yield of strange baryons.

We consider circular spinning string solutions in AdS₅×T^{1, 1} and calculate the quantum corrections to the energy at one-loop on worldsheet. The fluctuations are given as a set of harmonic oscillators and we calculate their normal mode frequency in closed form. The sum of frequency is equal to the one-loop string energy, which through AdS/CFT correspondence corresponds to the leading order correction of the conformal dimension for long operators in Klebanov–Witten conifold gauge field theory.

Interest on (2+1)-dimensional electron systems has increased considerably after the realization of novel properties of graphene sheets, in which the behavior of electrons is effectively described by relativistic equations. Having this fact in mind, the following problem is studied in this work: when a spin-1/2 particle is constrained to move on a curved surface, is it possible to describe this particle without giving reference to the dimensions external to the surface? As a special case of this, a relativistic spin-1/2 particle which is constrained to move on a (2+1)-dimensional hypersurface of the (3+1)-dimensional Minkowskian spacetime is considered, and an effective Dirac equation for this particle is derived using the so-called thin layer method. Some of the results are compared with those obtained in a previous work by Burgess and Jensen.

The center-of-mass (CM) energy of collision for two uncharged particles falling freely from rest at infinity is investigated in the background of charged, rotating and accelerating black hole. It is found that the CM energy of collision is unlimited at the acceleration horizon and at the event horizon (in the extremal case) if one of the colliding particles has critical angular momentum and the other one has a proper angular momentum such that the particle can reach the horizon.

We systematically derive a length scale characterizing the size of a low-lying, β stable nucleus from empirical data for the diffraction peak angle in the proton inelastic differential cross-section of incident energy of ~ 1 GeV. In doing so, we assume that the target nucleus in the ground state is a completely absorptive "black" sphere of radius a. The cross-section πa², where a is determined in such a way as to reproduce the empirical proton diffraction peak angle in the elastic channel, is known to agree with empirical total reaction cross-sections for incident protons to within error bars. By comparing the inelastic diffraction patterns obtained in the Fraunhofer approximation with the experimental ones, one can likewise derive the black sphere radius a_l for the excited state with spin l. We find that for ¹²C, ^{58, 60, 62, 64}Ni, and ²⁰⁸Pb, the value of a_l obtained from the inelastic channel is generally larger than the value of a from the elastic channel and tends to increase with the excitation energy. This increase is remarkable for the Hoyle state. Finally, we discuss the relation between a_l and the size of excited nuclei.