11,849 research outputs found
Single Top Quark in the SM and Beyond
No full textThe prospects of single top quark physics at colliders of the TeV energy scale are discussed. Single top quark study allows a direct measurement of the vertex and a precise probing physics beyond the Standard Model in various scenarios.The prospects of single top quark physics at colliders of the TeV energy scale are discussed. Single top quark study allows a direct measurement of the vertex and a precise probing physics beyond the Standard Model in various scenarios
Single top quark tW+X production at the CERN LHC: a closer look
No full textWe have reexamined the tW+X single top-quark production process which is important at the LHC contrary to the Tevatron. The special attention was paid to the treatment of the 2->2[Wt] process and the part of it's next-to-leading correction: 2->3[Wtb] process. We show that 2->3[Wtb] process has to be correctly taken into account with a proper subtraction of the top pair contribution and that it has qualitatively different kinematical distributions from the 2->2[Wt] process. We present the total cross section of the tW+X production to be about 62 pb at QCD scale be taken as a top quark mass, suggest the method of combining Wt and Wtb processes with gauge invariant subtraction of the tt-bar part which allows to reproduce correct kinematical properties and perform a proper event simulation of the tW+X process in the whole kinematical region.We have reexamined the tW+X single top-quark production process which is important at the LHC contrary to the Tevatron. The special attention was paid to the treatment of the 2->2[Wt] process and the part of it's next-to-leading correction: 2->3[Wtb] process. We show that 2->3[Wtb] process has to be correctly taken into account with a proper subtraction of the top pair contribution and that it has qualitatively different kinematical distributions from the 2->2[Wt] process. We present the total cross section of the tW+X production to be about 62 pb at QCD scale be taken as a top quark mass, suggest the method of combining Wt and Wtb processes with gauge invariant subtraction of the tt-bar part which allows to reproduce correct kinematical properties and perform a proper event simulation of the tW+X process in the whole kinematical region
CompHEP - PYTHIA interface: integrated package for the collision events generation based on exact matrix elements
No full textAzimuthal anisotropy of charged particles with transverse momentum up to 100 GeV/c in PbPb collisions at √sNN = 5.02 TeV
No full textThe Fourier coefficients v2 and v3 characterizing the anisotropy of the azimuthal distribution of charged particles produced in PbPb collisions at sNN=5.02TeV are measured with data collected by the CMS experiment. The measurements cover a broad transverse momentum range, 1<pT<100GeV/c. The analysis focuses on the pT>10GeV/c range, where anisotropic azimuthal distributions should reflect the path-length dependence of parton energy loss in the created medium. Results are presented in several bins of PbPb collision centrality, spanning the 60% most central events. The v2 coefficient is measured with the scalar product and the multiparticle cumulant methods, which have different sensitivities to initial-state fluctuations. The values from both methods remain positive up to pT∼60–80GeV/c, in all examined centrality classes. The v3 coefficient, only measured with the scalar product method, tends to zero for pT≳20GeV/c. Comparisons between theoretical calculations and data provide new constraints on the path-length dependence of parton energy loss in heavy ion collisions and highlight the importance of the initial-state fluctuations
Search for single production of vector-like quarks decaying to a b quark and a Higgs boson
No full textA search is presented for single production of heavy vector-like quarks (B) that decay to a Higgs boson and a b quark, with the Higgs boson decaying to a highly boosted bb¯ pair reconstructed as a single collimated jet. The analysis is based on data collected by the CMS experiment in proton-proton collisions at √‾s = 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1. The data are consistent with background expectations, and upper limits at 95% confidence level on the product of the B quark cross section and the branching fraction are obtained in the range 1.28–0.07 pb, for a narrow B quark with a mass between 700 and 1800 GeV. The production of B quarks with widths of 10, 20 and 30% of the resonance mass is also considered, and the sensitivities obtained are similar to those achieved in the narrow width case. This is the first search at the CERN LHC for the single production of a B quark through its fully hadronic decay channel, and the first study considering finite resonance widths of the B quark
L.A. Belyaev and the Archeology of the Volga Region
No full textThe article is dedicated to the jubilee of Leonid Andreevich Belyaev, a renowned Russian archaeologist, scientific figure, Corresponding Member of the Russian Academy of Sciences, and chief editor of the Russian Archaeology journal. The milestones of his life are considered along with the role of the Volga region archaeology in his development as a researcher, as well as the contribution made by Leonid Andreevich to the study of the medieval antiquities of the Volga region. Today, Leonid Andreevich Belyaev is one of the most recognised archaeologists-medievalists solving the fundamental theoretical problems of historical science, managing large field projects, and establishing new directions in the scientific research process. The range of Leonid Andreevich’s scientific interests vividly characterizes the tremendous scope of his personality
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