نتایج جستجو برای: b quark
تعداد نتایج: 924777 فیلتر نتایج به سال:
We study the semileptonic transitions Bc → ηc, J/ψ, D, D∗, B, B∗, Bs, B∗ s in the framework of a relativistic constituent quark model. We use experimental data on leptonic J/ψ decay, lattice and QCD sum rule results on leptonic Bc decay, and on radiative ηc transitions to adjust the quark model parameters. We compute all form factors of the above semileptonic Bc-transitions and give predictions...
Even before the top quark was discovered by the CDF[1] and DØ[2] experiments in 1995, several of its properties could be deduced from those of its weak partner, the bottom quark. The increment in the measured[3] value of R = σ(e +e−→hadrons) σ(e+e−→μ+μ−) at the b threshold agreed with the predicted δR = 13 , confirmingQ b = − 1 3 . Likewise, data[4] on the front-back asymmetry for electroweak b...
The couplings of the fermions to the Z boson are of great importance in establishing the validity of the Standard Model and in looking for physics beyond it. The couplings of the b-quark to the Z boson have been the subject of much experimental study and theoretical interpretation. The apparent excess in the value of R b, the ratio of the partial width of the Z boson to bb̄ to its total hadronic...
We study the B 0 s − B 0 s mixing amplitude in Standard Model by computing the relevant hadronic matrix element in the static limit of lattice HQET with the Neuberger light quark action. In the quenched approximation, and after matching to the MS scheme in QCD, we obtain B MS B s (m b) = 0.940(16)(22). c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCom...
The techniques used to study top quarks at hadron colliders are presented. The analyses that discovered the top quark are described, with emphasis on the techniques used to tag b quark jets in candidate events. The most recent measurements of top quark properties by the CDF and D0 / collaborations are reviewed, including the top quark cross section, mass, branching fractions and production prop...
We investigate the B meson light-cone distribution amplitudes in the heavyquark limit which are relevant for the QCD factorization approach for the exclusive B meson decays. We derive exact relations between twoand three-particle distribution amplitudes from the QCD equations of motion and heavy-quark symmetry constraint. As solution of these relations, we give representations for the quark-ant...
We discuss some new invariants of quark mixing and show their usefulness with a simple example. We also present some other new tools for analyzing quark mixing. ∗ talk presented at the Yukawa couplings and the origin of mass workshop, February 1994, University of Florida, Gainesville, Florida ∗∗address after September 1, 1994: Department of Physics, University of Pennsylvania, Philadelphia, PA ...
We give an introduction to the heavy-quark effective theory and the 1/mQ expansion, which provide the modern framework for a systematic, model-independent description of the properties and decays of hadrons containing a heavy quark. We discuss the applications of these concepts to spectroscopy and to the weak decays of B mesons. Lectures presented at the 34th International School of Subnuclear ...
We extract the total width of the top quark, Γ(t), from the partial decay width Γ(t → Wb) measured using the t-channel cross section for single top-quark production and from the branching fraction B(t → Wb) measured in tt events using up to 2.3 fb(-1) of integrated luminosity collected by the D0 Collaboration at the Tevatron pp Collider. The result is Γ(t) = 1.99(-0.55)(+0.69) GeV, which tran...
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