نتایج جستجو برای: b quark
تعداد نتایج: 924777 فیلتر نتایج به سال:
Methods of calculation of loop diagrams in Heavy Quark Effective Theory (HQET) are presented. 1 Hadrons with a Heavy Quark B meson is the hydrogen atom of Quantum Chromodynamics (QCD), its simplest nontrivial object. In the leading approximation, the b quark in it just seats at rest at the origin and creates chromoelectric field. Light constituents (gluons, light quarks and antiquarks) move in ...
We present the results of a search for pair production of a heavy toplike (t') quark decaying to Wq final states using data corresponding to an integrated luminosity of 5.6 fb(-1) collected by the CDF II detector in pp collisions at √s=1.96 TeV. We perform parallel searches for t'→Wb and t'→Wq (where q is a generic down-type quark) in events containing a lepton and four or more jets. By perform...
We extend the picture of B-meson decay constants obtained in lattice QCD beyond those of the B, Bs and Bc to give the first full lattice QCD results for the B , B s and B c. We use improved nonrelativistic QCD for the valence b quark and the highly improved staggered quark (HISQ) action for the lighter quarks on gluon field configurations that include the effect of u=d, s and c quarks in the se...
We study the fragmentation of the b quark in top decay in NLO QCD, within the framework of perturbative fragmentation, which allows one to resum large logarithms ∼ log(m 2 t /m 2 b). We show the b-energy distribution, which we compare with the exact O(α S) result for a massive b quark. We use data from e + e − machines in order to describe the b-quark hadronization and make predictions for the ...
Next-to-next-to-leading order vacuum polarization function of heavy quark near threshold and sum rules for b ¯ b system. Abstract A correlator of the vector current of a heavy quark is computed analytically near threshold in the next-to-next-to-leading order in perturbative and relativistic expansion that includes α 2 s , α s v and v 2 corrections in the coupling constant and velocity of the he...
We apply the method of perturbative fragmentation to study bottom fragmentation in top decay. We present the energy spectrum of b-quarks and b-flavoured hadrons in top decay. A reliable understanding of bottom-quark fragmentation in top-quark decay (t → bW) will be fundamental to accurately measure the top properties, such as its mass, at present and future high-energy colliders. At the LHC, fi...
We apply the method of perturbative fragmentation to study bottom fragmentation in top decay. We present the energy spectrum of b-quarks and b-flavoured hadrons in top decay. A reliable understanding of bottom-quark fragmentation in top-quark decay (t → bW) will be fundamental to accurately measure the top properties, such as its mass, at present and future high-energy colliders. At the LHC, fi...
This paper uses lattice QCD to calculate the decay constants of B and D mesons using an O(a)-improved action that takes light quark actions as a starting point, tuned so that it can be directly applied at the physical masses of the b and c quarks. The B meson decay constant f B is of particular phenomenological interest, since it is responsible for most of the uncertainty in current determinati...
In this article I will review the measurements of the b quark mass performed by ALEPH and DELPHI. A large set of observables has been used together with detailed studies on jet algorithms. Very clear effects due to the b quark mass running are observed , even if a wide spread in the results and the large systematic errors coming from hadronization corrections prevents to extract an average valu...
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