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Browsing Research Repository by Author "Barman, Nayan Moni"

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    Semileptonic B-meson decays in the Standard Model
    (Department of Physics, NITS, 2022) Barman, Nayan Moni
    Our current understanding of the laws of nature that govern the fundamental constituents of the Universe, the elementary particles and their interactions are well established within a model called the standard model of particle physics. The standard model of particle physics provides a systematic description of the known fundamental forces of nature and classifies all known elementary particles. The underlying frame work of the standard model assumes that the charged and neutral leptons are universal in weak interactions. In particular, the photon, the W± and Z boson couple in exactly the same manner to the three lepton generations. However, in recent years, several hints for the lepton flavor universality violation have been reported in various charged current b → cℓν and neutral-current b → sℓℓ quark level transitions. In particular, the experimental measurements of RD, RD∗, PD∗ τ , and FD∗ L in B→(D,D∗)ℓν decays and RJ/Ψ in Bc → J/Ψℓν decays proceeding via b → cℓν quark level transition deviate from standard model expectations at 1.4σ, 2.5σ, 1.6σ, 1.5σ, and 1.8σ, respectively. In this report, we perform a detailed standard model analysis of various semileptonic B-meson decays such as B → Dℓν, B → D∗ℓν, and Bc → J/Ψℓν proceeding via b → cℓν quark level transition. The primary concern of this work is to study the standard model flavor structure of semileptonic B-meson decays proceeding via charged-current b → cℓν quark level transition. In our analysis, we give predictions of several observables, such as the differential branching ratio DBR, the ratio of branching ratios R(P,V), the lepton side forward-backward asymmetry Aℓ FB, the longitudinal polarization fraction of the charged lepton Pℓ, and the longitudinal polarization fraction of the vector meson FV L in standard model using the effective field theory formalism.