D* polarization vs. R_{D^{(∗ )}} anomalies in the leptoquark models

2018/11/30 by Syuhei Iguro, Teppei Kitahara, Yuji Omura +2 · 1 citation
Physics and Astronomy · #Consistency (knowledge bases) #Focus (optics) #Leptoquark #Neutrino Physics Research #Physics beyond the Standard Model #Physics of Superconductivity and Magnetism #Polarization (electrochemistry) #Quantum Chromodynamics and Particle Interactions #Standard Model (mathematical formulation) #hep-ex #hep-ph

paper · pdf · doi:10.1007/jhep02(2019)194

published as JHEP 1902 (2019) 194 · 24 pages, 3 figures, 1 table; references added, version published in JHEP

openalex publication_date 2019/02/01 · arxiv created 2019/03/04 · arxiv updated 2019/03/05 · openalex created_date 2019/03/11 · openalex updated_date 2026/08/05

Abstract

A bstract Polarization measurements in B→ D^{(∗ )}τ ν <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>B</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mo>→</mml:mo> <mml:msup> <mml:mi>D</mml:mi> <mml:mfenced> <mml:mo>∗</mml:mo> </mml:mfenced> </mml:msup> <mml:mi>τ</mml:mi> <mml:mover> <mml:mi>ν</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> are useful to check consistency in new physics explanations for the R D and R_D^* <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:msup> <mml:mi>D</mml:mi> <mml:mo>*</mml:mo> </mml:msup> </mml:msub> </mml:math> anomalies. In this paper, we investigate the D * and τ polarizations and focus on the new physics contributions to the fraction of a longitudinal D * polarization ( F L D * ), which is recently measured by the Belle collaboration F L D * = 0 . 60 ± 0 . 09, in model-independent manner and in each single leptoquark model (R 2 , S 1 and U 1 ) that can naturally explain the R_{D^{(∗ )}} <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:msup> <mml:mi>D</mml:mi> <mml:mfenced> <mml:mo>∗</mml:mo> </mml:mfenced> </mml:msup> </mml:msub> </mml:math> anomalies. It is found that ℬ( B c + → τ + ν ) severely restricts deviation from the Standard Model (SM) prediction of F L , SM D * = 0 . 46±0 . 04 in the leptoquark models: [0 . 43 , 0 . 44], [0 . 42 , 0 . 48], and [0 . 43 , 0 . 47] are predicted as a range of F L D * for the R 2 , S 1 , and U 1 leptoquark models, respectively, where the current data of R_{D^{(∗ )}} <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:msup> <mml:mi>D</mml:mi> <mml:mfenced> <mml:mo>∗</mml:mo> </mml:mfenced> </mml:msup> </mml:msub> </mml:math> is satisfied at 1 σ level. It is also shown that the τ polarization observables can much deviate from the SM predictions. The Belle II experiment, therefore, can check such correlations between R_{D^{(∗ )}} <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:msup> <mml:mi>D</mml:mi> <mml:mfenced> <mml:mo>∗</mml:mo> </mml:mfenced> </mml:msup> </mml:msub> </mml:math> and the polarization observables, and discriminate among the leptoquark models.

Citations

• Minimally flavored colored scalar in B→ D^( * )τ ν and the mass matrices constraints
• Renormalization group evolution of the Standard Model dimension six operators II: Yukawa dependence
• CP-Violation in the Renormalizable Theory of Weak Interaction
• Scalar contributions to b→c(u)τν transitions
• Leptoquark mechanism of neutrino masses within the grand unification framework
• R(D∗), |Vcb|, and the Heavy Quark Symmetry relations between form factors

Cited by

• Low-energy phenomenology of scalar leptoquarks at one-loop accuracy