122512363
Exclusive meson production at HERMES
Abstract.Hard exclusive production of mesons in deep-inelastic scattering allows one to probe the so-far unknown Generalized Parton Distributions (GPDs) of the nucleon. The HERMES experiment has measured several different observables in exclusive meson production by scattering the 27.6GeV HERA lepton beam off an internal fixed gaseous target. Recent results on exclusive π+, ρ0 and pion pair production will be presented.
15360804
SUSY Searches in All-Hadronic States with Large MET at the LHC
The CMS and ATLAS search strategy for SUSY in inclusive multijet plus high missing transverse energy final states is reviewed. This canonical SUSY signature may be a viable discovery channel for low mass SUSY in the early phase of the LHC. Methods for Standard Model background estimates, MET studies and filters for instrumental background are presented.
119253725
Is the Lorentz limiting speed equal to the speed of light? Photons vs neutrino tests
We discuss the possibility that the “limiting speed” climit (cl) appearing in Lorentz equations might be different (i.e. slightly larger) than the observed speed of light cn. We show that such a possibility can be tested by state-of-the-art Michelson–Morley experiments, but also by careful measurement of neutrino speeds. It would indeed suffice to show that cn<cν≤cl. Quite interestingly, current limits from both approaches are competitive, in some circumstances. We also comment on competing tests using gamma-ray burst, assuming a dispersive character for the propagation of light.
119283868
Tidal capture of primordial black holes by neutron stars
The fraction of primordial black holes (PBHs) of masses 1017-1026g in the total amount of dark matter may be constrained by considering their capture by neutron stars (NSs), which leads to the rapid destruction of the latter. The constraints depend crucially on the capture rate which, in turn, is determined by the energy loss by a PBH passing through a NS. Two alternative approaches to estimate the energy loss have been used in the literature: the one based on the dynamical friction mechanism, and another on tidal deformations of the NS by the PBH. The second mechanism was claimed to be more efficient by several orders of magnitude due to the excitation of particular oscillation modes reminiscent of the surface waves. We address this disagreement by considering a simple analytically solvable model that consists of a flat incompressible fluid in an external gravitational field. In this model, we calculate the energy loss by a PBH traversing the fluid surface. We find that the excitation of modes with the propagation velocity smaller than that of PBH is suppressed, which implies that in a realistic situation of a supersonic PBH the large contributions from the surface waves are absent and the above two approaches lead to consistent expressions for the energy loss.
16746073
Generation of the baryon assymetry of the Universe within the left-right symmetric model
Abstract Fermions scattering off first-order phase transition bubbles, in the framework of SU(2) L ⊗ SU(2) R ⊗ U(1) models, may generate the Baryon Assymetry of the Universe (BAU), either at the LR-symmetry-breaking scale, or at the weak scale. In the latter case, the baryon assymetry of the Universe is related to CP violation in the K 0 − K 0 system.
118917259
Relating leptogenesis and dark matter
A scenario that relates the abundance of dark matter to the baryon asymmetry of the Universe is presented. In this scenario, based on a left-right extension of the Standard Model, dark matter is made of light, ~ 1 GeV, right-handed Majorana neutrinos.
122397416
Contribution to radiative corrections from decoupling particles
Particles which normally decouple in the large mass limit (i.e., unrelated to the symmetry breaking) may contribute to radiative corrections if their mass ismnew∼MW. We study their effect on various observables.