Possible lower bounds for the direct detection rate of SUSY dark matter

One can expect accessible lower bounds for the dark matter detection rate due to restrictions on masses of the SUSY partners. To explore this correlation, one needs a new-generation large-mass detector. The absolute lower bound for the detection rate can naturally be due to spin-dependent interaction. Aimed at detecting dark matter with sensitivity higher than 10^?5 event/kg/d, an experiment should have a nonzero-spin target. Perhaps, it is best to create a GENIUS-like detector with both ⁷³Ge (high spin) and ⁷⁶Ge nuclei.     

Search for Z* boson at ATLAS detector

We present the results of the search for new excited Z* boson at ATLAS detector in 2011. Results are based on the analysis of pp collisions at a center-of-mass energy of 7 TeV corresponding to an integrated luminosity of 4.9 fb^?1 in the dielectron channel and 5.0 fb^?1 in the dimuon channel. Since good agreement between experimental data and expectation of the Standard Model is observed in both channels, the existence of Z* is excluded with 95 percent confidence level for all masses below 2.20 TeV. The plans for Z* search in 2012 are discussed.     

A method of grid element cloning

A simple, reliable, and fast method of putting a new computational facilities into operation in a grid environment is described. This method was successfully tested as part of the grid segment at Dzhelepov Laboratory of Nuclear Problems, Joint Institute for Nuclear Research (JINR), for work at the ATLAS collaboration.     

Investigation of the dielectric properties of polymer composite films with a ferroelectric filler using the bridge and thermal noise methods

Thin films of composite polymers based on polyvinylidenfluoride (PVDF), with ferroelectric fillers of No-Zr-Ti-Pb (NZTP-l) were used to study the dielectric properties of the composites; specifically, we obtained the temperature dependence of the dielectric permittivity at various frequencies at various contents of filler piezoceramic in the polymers. Measurements were conducted using the bridge method and with the thermal noise method. In the studies with the bridge method, the range of the frequencies was 25 Hz-1 MHz; in the studies with the thermal noise method, the frequencies varied from 1 to 100 kHz.     

Proposal for chiral-boson search at LHC via their unique new signature

The resonance production of new chiral spin-1 bosons and their detection through the Drell-Yan process at the CERN LHC is considered. Quantitative evaluations of various differential cross sections of the chiral-boson production are made within the CalcHEP package. The new neutral chiral bosons can be observed as a Breit-Wigner resonance peak in the invariant-dilepton-mass distribution, as usual. However, unique new signatures of the chiral bosons exist. First, there is no Jacobian peak in the lepton transverse-momentum distribution. Second, the lepton angular distribution in the Collins—Soper frame for the high on-peak invariant masses of the lepton pairs has a peculiar “swallowtail” shape. The text was submitted by the authors in English.     

On the two-loop $$ \ma thcal{O} $$( αs2) correc tions to the pole mass of the t quark in the MSSM

The paper is devoted to the calculation of two-loop (α _s ²) MSSM corrections to the relation between the pole mass of the t quark and its running mass in the scheme. Firstly, the value of the second-order contribution from large-mass expansion in mt/M _SUSY is studied. Contrary to our expectations, this contribution turned out to be negligible. As a by-product of this calculation, the two-loop anomalous dimension of the running quark mass is obtained in the supersymmetric QCD. Secondly, the influence of the two-loop corrections to the t-quark mass on the predicted superpartner masses is investigated. The text was submitted by the authors in English.     

Nuclear spin structure in dark matter search: The finite momentum transfer limit

Spin-dependent elastic scattering of weakly interacting massive dark matter particles (WIMP) off nuclei is reviewed. All available, within different nuclear models, structure functions S(q) for finite momentum transfer (q > 0) are presented. These functions describe the recoil energy dependence of the differential event rate due to the spin-dependent WIMP-nucleon interactions. This paper, together with the previous paper “Nuclear Spin Structure in Dark Matter Search: The Zero Momentum Transfer Limit,” completes our review of the nuclear spin structure calculations involved in the problem of direct dark matter search.     

Interpreting the data on helium-ion scattering in metallic films

Earlier measurements of angular distributions in the multiple scattering of a helium-ion beam with energy below 300 keV on Al yielded rather unexpected results: the ratio between the half-width of the measured angular distribution, (θ_1/2)_e, and that predicted with the Moliere–Bethe theory, (θ_1/2)_MB, proved to stay almost constant throughout the investigated energy range. At the same time, one could expect the (θ_1/2)_e/(θ_1/2)_MB value to be affected by the beam-content variation due to the charge–exchange scattering. Towards resolving this problem, we compute the interaction potentials between the Не⁺⁺, Не⁺, and Не⁰ ions and the scattering atoms and reveal the electron-screening effects on the scattering process. Thereby, we explain the energy dependence of (θ_1/2)_e/(θ_1/2)_MB observed in the old and new measurements carried out at higher beam energies.     

Anomalously interacting new extra vector bosons and their first LHC constraints

In this review phenomenological consequences of the Standard Model extension by means of new spin-1 chiral fields with the internal quantum numbers of the electroweak Higgs doublets are summarized. The prospects for resonance production and detection of the chiral vector Z* and W*^± bosons at the LHC energies are considered on the basis of quantitative simulations within the CompHEP/CalcHEP package. The Z* boson can be observed as a Breit-Wigner resonance peak in the invariant dilepton mass distributions in the same way as the well-known extra gauge Z?? bosons. However, the Z* bosons have unique signatures in transverse momentum, angular and pseudorapidity distributions of the final leptons, which allow one to distinguish them from other heavy neutral resonances. In 2010, with 40 pb^?1 of the LHC proton-proton data at the energy 7 TeV, the ATLAS detector was used to search for narrow resonances in the invariant mass spectrum of e ⁺ e ^? and ??⁺??^? final states and high-mass charged states decaying to a charged lepton and a neutrino. No statistically significant excess above the Standard Model expectation was observed. The exclusion mass limits of 1.15 and 1.35 TeV/c ² were obtained for the chiral neutral Z* and charged W* bosons, respectively. These are the first direct limits on the W* and Z* boson production. Based on the above, a novel strategy for the chiral boson search in the LHC dijet data is discussed. For almost all currently considered exotic models the relevant signal is expected in the central dijet rapidity region y _1,2 ? 0 and |y ₁ ? y ₂| ? 0. On the contrary, the chiral bosons do not contribute to this region but produce an excess of dijet events far away from it. In particular, for these bosons the appropriate kinematical restrictions lead to a dip in the centrality ratio distribution over the dijet invariant mass instead of a bump expected in the most exotic models.