TY - JOUR
T1 - Flavor anomalies in leptoquark model with gauged U (1)Lμ-Lτ
AU - Chen, Chuan Hung
AU - Chiang, Cheng Wei
N1 - Publisher Copyright:
© 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.
PY - 2024/4/1
Y1 - 2024/4/1
N2 - In addition to anomalies associated with the muon g-2 and the branching ratio (BR) of B→D(∗)τν¯, Belle II recently observed an unexpectedly large BR in the B+→K+νν¯ decay. To resolve the anomalous excesses in these observables, we propose a framework involving a leptoquark, denoted by S1, which has the feature that down-type quarks merely couple to neutrinos but not the charged leptons, avoiding the strict constraint from the Bs→μ-μ+ decay. With the introduction of the U(1)Lμ-Lτ gauge symmetry, the Z′ with light mass not only resolves the muon g-2 anomaly, but also ensures that S1 couples exclusively to the third-generation leptons so that only τν¯τ and τ-neutrino modes are involved in the processes b→cℓν¯ and b→sνν¯, respectively. Under the dominant constraints from |ΔF|=2 processes, we find that the S1 contributions to the BRs of B→K(∗)νν¯ and KL→π0νν¯ can be factorized into the same multiplicative factor multiplying the standard model predictions, and the enhancement can be up to a factor of 2. In particular, B(K+→π+νν¯) can reach the upper 1σ error of the experimental value, i.e., ≃15.4×10-11. We also show that the model can fit the new world averages of R(D(∗)) and contribute significantly to the τ polarization in the B→Dτν¯ decay and B(Bc→τν¯).
AB - In addition to anomalies associated with the muon g-2 and the branching ratio (BR) of B→D(∗)τν¯, Belle II recently observed an unexpectedly large BR in the B+→K+νν¯ decay. To resolve the anomalous excesses in these observables, we propose a framework involving a leptoquark, denoted by S1, which has the feature that down-type quarks merely couple to neutrinos but not the charged leptons, avoiding the strict constraint from the Bs→μ-μ+ decay. With the introduction of the U(1)Lμ-Lτ gauge symmetry, the Z′ with light mass not only resolves the muon g-2 anomaly, but also ensures that S1 couples exclusively to the third-generation leptons so that only τν¯τ and τ-neutrino modes are involved in the processes b→cℓν¯ and b→sνν¯, respectively. Under the dominant constraints from |ΔF|=2 processes, we find that the S1 contributions to the BRs of B→K(∗)νν¯ and KL→π0νν¯ can be factorized into the same multiplicative factor multiplying the standard model predictions, and the enhancement can be up to a factor of 2. In particular, B(K+→π+νν¯) can reach the upper 1σ error of the experimental value, i.e., ≃15.4×10-11. We also show that the model can fit the new world averages of R(D(∗)) and contribute significantly to the τ polarization in the B→Dτν¯ decay and B(Bc→τν¯).
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U2 - 10.1103/PhysRevD.109.075004
DO - 10.1103/PhysRevD.109.075004
M3 - Article
AN - SCOPUS:85189892231
SN - 2470-0010
VL - 109
JO - Physical Review D
JF - Physical Review D
IS - 7
M1 - 075004
ER -