Chiral gauge leptoquark mass limits and branching ratios of $ K_L^0, B^0, B_s \to l^+_i l^-_j $ decays with account of the general fermion mixing in leptoquark currents
M. V. Martynov, A. D. Smirnov
备注：
13 pages, 1 table, accepted for publication in Modern Physics Letters A
发表信息：
Modern Physics Letters A, Vol. 36, No. 04 (2021) 2150018 (15 pages)
The contributions of the chiral gauge leptoquarks $V^{L,R}$ induced by the chiral four color quark-lepton symmetry to the branching ratios of $ K_L^0, B^0, B_s \to l_1 \, l_2 $ decays are calculated and analysed using the general parametrizations of the fermion mixing matrices in the leptoguark currents. From the current experimental data on these decays under assumption $ m_{V^L} \ll m_{V^R} $ the lower mass limit $ m_{V^L} \cos{γ_L} > 5.68 \,\, \mbox{TeV}$ is found, which in particular case of equal gauge coupling constants gives $ m_{V^L} > 8.03 \,\, \mbox{TeV} $. The branching ratios of the decays under consideration predicted by the chiral gauge leptoquarks are calculated and analysed in dependence on the leptoquark masses and the mixing parameters. It is shown that in consistency with the current experimental data these branching ratios for $ B_s, B^0 \to μe $ decays can be close to their experimental limits and those for $ B_s, B^0 \to τe, τμ$ decays can be of order of~$10^{-7}$. The calculated branching ratios will be useful in the further experimental searches for these decays.
The contributions of the vector leptoquarks of Pati-Salam type to the branching ratios of $K_L^0, B^0, B_s \to l \, l^{\prime}$ decays are calculated with account of the fermion mixing in the leptoguark currents of the general type. Using the general parametrizations of the mixing matrices the lower vector leptoquark mass limit $ m_V > 86 \,\, TeV $ is found from the current experimental data on these decays. The branching ratios of the decays $B^0, B_s \to l \, l^{\prime}$ predicted at $m_V = 86 \,\, TeV$ are calculated. These branching ratios for the decays $ B^0, B_s \to μ^+ μ^-, e μ$ are c…
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We present an economical model where an $S^{}_1$ leptoquark and an anomaly-free $U(1)^{}_X$ gauge symmetry with $X = B^{}_3-2L^{}_μ/3-L^{}_τ/3$ are introduced, to account for the muon anomalous magnetic moment $a^{}_μ\equiv (g^{}_μ-2)$ and flavor puzzles including $R^{}_{K^{(\ast)_{}}}$ and $R^{}_{D^{(\ast)_{}}}$ anomalies together with quark and lepton flavor mixing. The $Z^\prime_{}$ gauge boson associated with the $U(1)^{}_X$ symmetry is responsible for the $R^{}_{K^{(\ast)_{}}}$ anomaly. Meanwhile, the specific flavor mixing patterns of quarks and leptons can be generated after the spontan…
Leptoquarks (LQs) are predicted within Grand Unified Theories and are well motivated by the current flavor anomalies. In this article we investigate the impact of scalar LQs on Higgs decays and oblique corrections as complementary observables in the search for them. Taking into account all five LQ representations under the Standard Model gauge group and including the most general mixing among them, we calculate the effects in $h\toγγ$, $h\to gg$, $h \to Z γ$ and the Peskin-Takeuchi parameters $S$, $T$ and $U$. We find that these observables depend on the same Lagrangian parameters, leading to …
We scrutinize the impact of various relevant scalar leptoquarks on the physical observables associated with the rare semileptonic decay processes of $B_s$ meson involving $b \to (u, c) l\bar ν_l$ quark level transitions. We constrain the new parameter space consistent with the experimental limit on Br($B_{u,c} \to τν_l$), Br($B \to πτ\bar ν_τ$), $R_{D^{(*)}}, R_{J/ψ}$ and $R_π^l$ observables. Using the allowed parameter space, we compute the branching ratios, forward-backward asymmetries, lepton and hardon polarization asymmetries of $B_s \to (K^{(*)}, D_s^{(*)}) τ\bar ν_τ$ decay modes. Forbye…
