$\frac{|V_{ub}|}{|V_{cb}|}$ and Quest for New Physics

Abstract

Charged current semi-leptonic decays of $B$-meson are important for a precise determination of the CKM elements. The CKM elements $|V_{ub}|$ and $|V_{cb}|$ show a discrepancy between the exclusive and inclusive determinations. These determinations are however masked with hadronic and other uncertainties, and thus can't be unambiguously taken as implying new physics. In the present study, we propose a new observable: the ratio of these two CKM elements, $R_V\equiv \frac{|V_{ub}|}{|V_{cb}|}$, which is found to receive negligible corrections due to hadronic as well as QED effects. Interestingly, $R_V$ as constructed from exclusive determinations of $|V_{ub}|$ and $|V_{cb}|$ agrees quite well with that constructed from the inclusive determinations of these CKM elements. Hence, we propose that $R_V$ is a better and cleaner observable, and can serve as an excellent tool for the test of the Standard Model. We also provide an example of its probing power.

arXiv comment30 pages, 6 figures

References in corpus (47)

• PHOTOS Monte Carlo: a precision tool for QED corrections in Z and W decays
• More Model-Independent Analysis of b->s Processes
• On the Standard Model predictions for $R_K$ and $R_{K^{\ast }}$
• On the B to D* tau nu Sensitivity to New Physics
• Angular Distributions of B -> K ll Decays
• $R_K$ and future $b\to s\ell \ell$ BSM opportunities
• Simultaneous Explanation of the $R_K$ and $R(D^{(\ast )})$ Puzzles
• The lifetime of the $B_c^{-}$ meson and the anomalies in $B\to D^{(\ast )}\tau \nu$
• Explaining B->Dτν, B->D*τνand B->τνin a 2HDM of type III
• ${\Lambda }_b\to p{\ell }^{-}{\bar{\nu }}_{\ell }$ and ${\Lambda }_b\to {\Lambda }_c{\ell }^{-}{\bar{\nu }}_{\ell }$ form factors from lattice QCD with relativistic heavy quarks
• Extraction of $|V_{cb}|$ from $B\to D^{(\ast )}\ell {\nu }_{\ell }$ and the Standard Model predictions of $R(D^{(\ast )})$
• Theory of Charmless Inclusive B Decays and the Extraction of V_{ub}
• Determination of the quark coupling strength $|V_{ub}|$ using baryonic decays
• A fresh look at the determination of |V_cb| from B-> D^* l nu
• Precision determination of the CKM element Vcb
• The $V_{cb}$ puzzle: an update
• $B\to \pi \ell {\nu }_l$ Width and $|V_{ub}|$ from QCD Light-Cone Sum Rules
• B -> D tau nu Branching Ratios: Opportunity for Lattice QCD and Hadron Colliders
• Model-Independent Extraction of |V_{cb}| Using Dispersion Relations
• Inclusive semileptonic B decays and the determination of |V_ub|
• Towards the Identification of New Physics through Quark Flavour Violating Processes
• The B -> pi l nu semileptonic form factor from three-flavor lattice QCD: A model-independent determination of |V(ub)|
• Can the differences in the determinations of $V_{ub}$ and $V_{cb}$ be explained by New Physics?
• Inclusive semileptonic fits, heavy quark masses, and V_cb
• Effects of right-handed charged currents on the determinations of |V_ub| and |V_cb|
• The effect of H^\pm on B^\pm -> τ^\pm νand B^\pm -> μ^\pm ν
• Model-Independent Extraction of $|V_{cb}|$ from $\bar{B}\to D^{\ast }\ell \overline{\nu }$
• QED Corrections in $\bar{B}\to \bar{K}{\ell }^{+}{\ell }^{-}$ at the Double-Differential Level
• Perturbative corrections to $B\to D$ form factors in QCD
• Extracting V_{ub} Without Recourse to Structure Functions
• Challenges in Semileptonic B Decays
• B decay shape variables and the precision determination of |Vcb| and mb
• Charged Higgs on $B^{-}\to \tau {\bar{\nu }}_{\tau }$ and $\bar{B}\to P(V)\ell {\bar{\nu }}_{\ell }$
• Left-right mixing on leptonic and semileptonic $b\to u$ decays
• Tension in the inclusive versus exclusive determinations of $|V_{cb}|$: a possible role of new physics
• Soft-Photon Corrections to $\bar{B}\to D{\tau }^{-}{\bar{\nu }}_{\tau }$ Relative to $\bar{B}\to D{\mu }^{-}{\bar{\nu }}_{\mu }$
• Soft-photon corrections in multi-body meson decays
• PHOTOS Interface in C++; Technical and Physics Documentation
• Complete Michel Parameter Analysis of inclusive semileptonic b \to c transition
• Limits on New Physics from exclusive $B\to D^{(\ast )}\ell \bar{\nu }$ Decays
• New physics in inclusive semileptonic $B$ decays including nonperturbative corrections
• Form factor ratios for $B_s\to K\ell \nu$ and $B_s\to D_s\ell \nu$ semileptonic decays and $|V_{ub}/V_{cb}|$
• Impacts of radiative corrections on measurements of lepton flavour universality in $B\to D\ell {\nu }_{\ell }$ decays
• Mapping out the Space for New Physics with Leptonic and Semileptonic $B_{(c)}$ Decays
• A closer look at the extraction of $|V_{ub}|$ from $B\to \pi l\nu$
• Determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$
• On the Impact of Soft Photons on $B\to K{\ell }^{+}{\ell }^{-}$