$B_c\to J/\psi$ helicity form factors and the $B_c^{+}\to J/\psi +(P,V,{\ell }^{+}{\nu }_{\ell })$ decays

Abstract

In this paper, we calculate the $B_c\to J/\psi$ helicity form factors (HFFs) up to twist-4 accuracy by using the light-cone sum rules (LCSR) approach. After extrapolating those HFFs to the physically allowable $q^2$ region, we investigate the $B_c^{+}$-meson two-body decays and semi-leptonic decays $B_c^{+}\to J/\psi +(P,V,{\ell }^{+}{\nu }_{\ell })$ with $P/V$ stands for light pseudoscalar/vector meson, respectively. The branching fractions can be derived by using the CKM matrix element and the $B_c$ lifetime from the Particle Data Group, and we obtain $\mathcal{B}(B_c^{+}\to J/\psi {\pi }^{+})=(0.136_{-0.002}^{+0.002})\%$, $\mathcal{B}(B_c^{+}\to J/\psi K^{+})=(0.010_{-0.000}^{+0.000})\%$, $\mathcal{B}(B_c^{+}\to J/\psi {\rho }^{+})=(0.768_{-0.033}^{+0.029})\%$, $\mathcal{B}(B_c^{+}\to J/\psi K^{\ast +})=(0.043_{-0.001}^{+0.001})\%$, $\mathcal{B}(B_c^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu })=(2.802_{-0.675}^{+0.526})\%$ and $\mathcal{B}(B_c^{+}\to J/\psi {\tau }^{+}{\nu }_{\tau })=(0.559_{-0.170}^{+0.131})\%$. We then obtain ${\mathcal{R}}_{{\pi }^{+}/{\mu }^{+}{\nu }_{\mu }}=0.048_{-0.012}^{+0.009}$ and ${\mathcal{R}}_{K^{+}/{\pi }^{+}}=0.075_{-0.005}^{+0.005}$, which agree with the LHCb measured value within $1\sigma$-error. We also obtain ${\mathcal{R}}_{J/\psi }=0.199_{-0.077}^{+0.060}$, which like other theoretical predictions, is consistent with the LHCb measured value within $2\sigma$-error. Those imply that the HFFs under the LCSR approach are also applicable to the $B_c^{+}$ meson two-body decays and semi-leptonic decays $B_c^{+}\to J/\psi +(P,V,{\ell }^{+}{\nu }_{\ell })$, and the HFFs obtained by using LCSR in a new way implies that there may be new physics in the $B_c\to J/\psi {\ell }^{+}{\nu }_{\ell }$ semi-leptonic decays.

arXiv comment10 pages, 4 figures, published version

References in corpus (31)

• Weak Decays Beyond Leading Logarithms
• B_{d,s}->rho, omega, K*, phi Decay Form Factors from Light-Cone Sum Rules Revisited
• Exclusive Semileptonic and Rare B-Meson Decays in QCD
• Measurement of the ratio of branching fractions $\mathcal{B}(B_c^{+}\to J/\psi {\tau }^{+}{\nu }_{\tau })$/$\mathcal{B}(B_c^{+}\to J/\psi {\mu }^{+}{\nu }_{\mu })$
• Weak decays of the B_c meson to charmonium and D mesons in the relativistic quark model
• Use and Misuse of QCD Sum Rules in Heavy-to-light Transitions: the Decay $B\to \rho e\nu$ Reexamined
• Lattice QCD and QCD Sum Rule determination of the decay constants of eta_c, J/psi and hc states
• Theoretical and Phenomenological Constraints on Form Factors for Radiative and Semi-Leptonic B-Meson Decays
• Semileptonic decays $B_c\to ({\eta }_c,J/\Psi )l\nu$ in the perturbative QCD approach
• Footprints of New Physics in $b\to c\tau \nu$ Transitions
• Semileptonic and non-leptonic B_c decays
• |V_td/V_ts| from B-> V gamma
• Semileptonic charm decays $D\to \pi l{\nu }_{ł}$ and $D\to Kl{\nu }_l$ from QCD Light-Cone Sum Rules
• $B_c$ Exclusive Decays to Charmonium and a Light Meson at Next-to-Leading Order Accuracy
• Recent Anomalies in B Physics
• The decays $B_c\to J/\psi +\bar{\ell }{\nu }_{\ell }$ and $B_c\to J/\psi +\pi (K)$ in covariant confined quark model
• On lepton flavour universality in semileptonic $B_c\to {\eta }_c,J/\psi$ decays
• The study of leading twist light cone wave functions of J/Psi meson
• Transitions of $B_c\to \psi (1S,2S)$ and the modified harmonic oscillator wave function in LFQM
• Measurement of the ratio of $B_c^{+}$ branching fractions to $J/\psi {\pi }^{+}$ and $J/\psi {\mu }^{+}{\nu }_{\mu }$
• Lepton flavor universality violation in semileptonic tree level weak transitions
• Heavy Pseudoscalar Leading-Twist Distribution Amplitudes within QCD Theory in Background Fields
• QCD corrections to the $B_c$ to charmonia semi-leptonic decays
• The $\rho$-meson longitudinal leading-twist distribution amplitude within QCD background field theory
• The longitudinal leading-twist distribution amplitude of $J/\psi$ meson within background field theory
• $B\to \rho$ transition form factors within the QCD light-cone sum rules and the $\rho$-meson leading-twist distribution amplitude
• $B\to K^{\ast }$ Transition Form Factors and the Semi-leptonic Decay $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$
• The $B\to \rho$ helicity form factors within the QCD light-cone sum rules
• Relativistic calculations of $R(D^{(\ast )})$, $R(D_s^{(\ast )})$, $R({\eta }_c)$ and $R(J/\psi )$
• Branching fractions and polarizations of $D\to V(\omega ,\rho ,K^{\ast })\ell {\nu }_{\ell }$ within QCD LCSR
• Revisiting the production of $J/\psi +{\eta }_c$ via the $e^{+}{e}^{-}$ annihilation within the QCD light-cone sum rules

Cited by in corpus (3)

• Observation of the $B_c^{+}\to J/\psi {\pi }^{+}{\pi }^0$ decay
• Searching $B_c^{\ast }$ via conservation laws
• $B_{(s)}\to S(a_0(1450),K_0^{\ast }(1430),f_0(1500))$ helicity form factors within QCD light-cone sum rules