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V. A. Bednyakov

Publications and source records attributed to V. A. Bednyakov.

62 records · Page 4Linked to original sources
arXiv1996

Superlight neutralino as a dark matter particle candidate

We address the question of how light can be the lightest supersymmetric particle neutralino to be a reliable cold dark matter (CDM) particle candidate. To this end we have performed a combined analysis of the parameter space of the Minimal Supersymmetric Standard Model (MSSM) taking into account cosmological and accelerator constraints including those from the radiative $b\rightarrow sγ$ decay. Appropriate grand unification (GUT) scenarios were considered. We have found that the relaxation of gaugino mass unification is sufficient to obtain a phenomenologically and cosmologically viable solution of the MSSM with the neutralino as light as 3~GeV. We have found good prospects for direct detection of these superlight CDM neutralinos via elastic scattering off various nuclei in the forthcoming experiments with low-threshold DM detectors. In a certain sense, these experiments can probe the gaugino mass unification giving constraints on the possible GUT scenarios within the MSSM.

hep-ph↗
arXiv1996

Is SUSY accessible by direct dark matter detection?

We performed a combined analysis of the parameter space of the Minimal Supersymmetric Standard Model (MSSM) taking into account cosmological and accelerator constraints including those from the radiative $b\rightarrow sγ$ decay measured by the CLEO collaboration. Special attention is paid to the event rate, $R$, of direct dark matter neutralino detection. We have found domains of the parameter space with $R\simeq 5-10$~events/kg/day. This would be within the reach of current dark matter experiments. The $b\rightarrow sγ$ data do not essentially reduce these large event rate domains of the MSSM parameter space.

hep-ph↗
arXiv1995

Expectations for Supersymmetric Dark Matter Searches Underground

We consider the neutralino as a dominant Dark Matter particle in the galactic halo and investigate some general issues of direct Dark Matter searches via elastic neutralino-nucleus scattering. On the basis of conventional assumptions about the nuclear and nucleon structure we analyse constraints on SUSY model parameter space accessible by the direct Dark Matter searches. This analysis shows that Dark Matter detectors fall into the THREE different categories with respect to their sensitivity to different groups of the SUSY model parameters. We calculate the event rate for various experimentally interesting isotopes within the Minimal Supersymmetric Standard Model (MSSM) taking into account the known accelerator and cosmological constraints on the MSSM parameter space. We investigate the role of nuclear spin in elastic neutralino - nucleus scattering. It is found that the contribution of the spin-dependent interaction to this process is subdominant for nuclei with atomic weights A > 50.

hep-ph↗
arXiv1994

Bounds on the Ratio of Higgs Vacuum Expectation Values in the Minimal Supersymmetric Standard Model from the Top and Bottom Quark Masses

The top quark mass values from the CDF Collaboration and the precision electroweak data at LEP combined with the bottom mass value allow to establish bounds on the parameter tan beta in the minimal supersymmetric standard model (MSSM) independent of the soft supersymmetry breaking parameters. We find: 0.96 < tan beta < 52.2 at the 95 % C.L., which is mostly the region tan beta >1, where radiative electroweak symmetry breaking is possible. Assuming electroweak symmetry breaking leads to: tan beta=1.2 +- 0.2, if one neglects the high tan beta solution, which is unlikely due to proton lifetime limits.

hep-ph↗
arXiv1994

On leading charmed meson production in $π$-nucleon interactions

It is shown that the D--meson, whose light quark is the initial-pion valence quark and whose charmed quark is produced in annihilation of valence quarks and has got a large enough momentum, is really a leading meson in reactions like $π^- p -> DX$. If such annihilation of valence quarks from initial hadrons is impossible there must be no distinct leading effect.

hep-ph↗
arXiv1994

Possible constraints on SUSY-model Parameters from Direct Dark Matter Search

We consider the SUSY-model neutralino as a dominant Dark Matter particle in the galactic halo and investigate some general issues of direct DM searches via elastic neutralino-nucleus scattering. On the basis of conventional assumptions about the nuclear and nucleon structure, without referring to a specific SUSY-model, we prove that it is impossible in principle to extract more than three constraints on fundamental SUSY-model parameters from the direct Dark matter searches. Three types of Dark matter detectors probing different groups of parameters are recognized.

hep-ph↗
arXiv1994

On SUSY Dark Matter Detection with Spinless Nuclei

We investigate the role of nuclear spin in elastic scattering of Dark Matter (DM) neutralinos from nuclei in the framework of the Minimal SUSY standard model (MSSM). The relative contribution of spin-dependent axial-vector and spin-independent scalar interactions to the event rate in a DM detector has been analyzed for various nuclei. Within general assumptions about the nuclear and nucleon structure we find that for nuclei with atomic weights $A > 50$ the spin-independent part of the event rate $R_{si}$ is larger than the spin-dependent one $R_{sd}$ in the domain of the MSSM parameter space allowed by the known experimental data and where the additional constraint for the total event rate $R =R_{sd} + R_{si} > 0.01$ is satisfied. The latter reflects realistic sensitivities of present and near future DM detectors. Therefore we expect equal chances for discovering the DM event either with spin-zero or with spin-non-zero isotopes if their atomic weights are $A_{1} \sim A_{2} > 50$.

hep-ph↗