Rare ${\Lambda }_b\to \Lambda$ l${}^{+}$ l${}^{-}$ Decays with Polarized $\Lambda$

Abstract

We investigate the rare baryonic exclusive decays of ${\Lambda }_b\to \Lambda l^{+}{l}^{-}(l=e,\mu ,\tau )$ with polarized $\Lambda$. Under the approximation of the heavy quark effective theory (HQET), in the standard model we derive the differential decay rates and various polarization asymmetries by including lepton mass effects. We find that with the long-distance effects the decay branching ratios are $5.3\times 10^{-5}$ for ${\Lambda }_b\to \Lambda l^{+}{l}^{-}(l=e,\mu )$ and $1.1\times 10^{-5}$ for ${\Lambda }_b\to \Lambda {\tau }^{+}{\tau }^{-}$. The effects of new physics in the decay rates are also discussed. The integrated longitudinal $\Lambda$ polarizations are -0.31 and -0.12, while that of the normal ones 0.02 and 0.01, for di-muon and tau modes, respectively. The CP-odd transverse polarization of $\Lambda$ is zero in the standard model but it is expected to be sizable in some theories with new physics.

12 pages, 12 figures, some typos corrected, Phys.Rev.D version

Cited by in corpus (34)

• ${\Lambda }_b\to \Lambda {\ell }^{+}{\ell }^{-}$ form factors, differential branching fraction, and angular observables from lattice QCD with relativistic $b$ quarks
• Form Factors for Lambda_b -> Lambda Transitions in SCET
• Baryonic Rare Decays of ${\Lambda }_b\to \Lambda {\ell }^{+}{\ell }^{-}$
• Rare baryon decays Lambda_b -> Lambda l+ l- (l=e, mu, tau) and Lambda_b -> Lambda gamma : Differential and total rates, lepton- and hadron-side forward-backward asymmetries
• Rare Decays of Λ_b->Λ+ γand Λ_b ->Λ+ l^{+} l^{-} in the Light-cone Sum Rules
• Analysis of the $Λ_{b}\rar Λ\ell^+\ell^- $ decay in QCD
• Rare dileptonic decays of Λ_b in a quark model
• Lambda_b -> Lambda l+ l- form factors and differential branching fraction from lattice QCD
• Measurement of the differential branching fraction of the decay ${\Lambda }_b^0\to \Lambda {\mu }^{+}{\mu }^{-}$
• Weak decays of doubly heavy baryons: the FCNC processes
• Exclusive (Lambda_b -> Lambda l^+ l^-) decay beyond standard model
• Exclusive semileptonic decays of ${\Lambda }_b\to \Lambda l^{+}{l}^{-}$ in supersymmetric theories
• Model independent New Physics analysis in ${\Lambda }_b\to \Lambda {\mu }^{+}{\mu }^{-}$ decay
• (Lambda_b -> Lambda l^+ l^-) decay in universal extra dimensions
• Semileptonic ${\Lambda }_{b,c}$ to Nucleon Transitions in Full QCD at Light Cone
• T violation in ${\Lambda }_b\to \Lambda {\ell }^{+}{\ell }^{-}$ decays with polarized $\Lambda$
• Rare decays of ${\Lambda }_b\to \Lambda \gamma$ and ${\Lambda }_b\to \Lambda l^{+}{l}^{-}$ in universal extra dimension model
• T violation in (Lambda_b -> Lambda l^+ l^-) decay beyond standard model
• Forward-backward asymmetries in (Lambda_b -> Lambda l^+ l^-) decay beyond the standard model
• Lepton mass effects and angular observables in ${\Lambda }_b\to \Lambda (\to p\pi ){\ell }^{+}{\ell }^{-}$
• Effect of both Z and Z'-mediated flavor-changing neutral currents on the baryonic rare decay $lambd{a}_b$ decays into $lambda{l}^{+}{l}^{-}$
• Lepton polarization asymmetries for FCNC decays of the ${\Lambda }_b$ baryon
• Study of ${\Lambda }_b\to \Lambda (\varphi ,{\eta }^{(\prime )})$ and ${\Lambda }_b\to \Lambda K^{+}{K}^{-}$ decays
• FCNC transitions of ${\Lambda }_b$ to neutron in Bethe-Salpeter equation approach
• T violation in ${\Lambda }_b\to \Lambda {\ell }^{+}{\ell }^{-}$ decays
• Analysis of ${\Lambda }_b\to \Lambda l^{+}{l}^{-}$ rare decays in a non-universal $Z^{\prime }$ model
• Tree Level Semileptonic ${\Sigma }_b$ to Nucleon Decay in Light Cone QCD Sum Rules
• Rare ${\Lambda }_b\to \Lambda l^{+}{l}^{-}$ decay in the Bethe-Salpeter equation approach
• Rare ${\Lambda }_c$ decays and new physics effects
• Flavor Changing Neutral Currents Transition of the ${\Sigma }_Q$ to Nucleon in Full QCD and Heavy Quark Effective Theory
• ${\Lambda }_b\to \Lambda (\to p{\pi }^{-}){\ell }^{+}{\ell }^{-}$ as probe of CP-violating New Physics
• Probing new physics effects in ${\Lambda }_b\to \Lambda (\to p{\pi }^{-}){\ell }^{+}{\ell }^{-}$ decay via model independent approach
• Baryons and baryoniums in the perspective of QCD sum rules
• Forward-backward asymmetries in ${\Lambda }_b\to \Lambda l^{+}{l}^{-}$ in Bethe-Salpeter equation approach