$$b \rightarrow c$$ semileptonic sum rule: extension to angular observables

Abstract Lepton flavor universality is a key prediction of the Standard Model of particle physics, and any violation of it immediately indicates the existence of new physics. Given the recent discrepancy of more than $$4\sigma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mn>4</mml:mn> <mml:mi>σ</mml:mi> </mml:mrow> </mml:math> in charged current semileptonic B meson decays and the absence of evident signals at the Large Hadron Collider, independent cross-checks become invaluable. In this context, $$b \rightarrow c$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>b</mml:mi> <mml:mo>→</mml:mo> <mml:mi>c</mml:mi> </mml:mrow> </mml:math> semileptonic sum rules based on heavy quark symmetry are interesting, since they allow us to check the consistency of experimental results. In this paper, we report newly found sum rules among angular observables of mesonic and baryonic $$b\rightarrow c l {\overline{\nu }}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>b</mml:mi> <mml:mo>→</mml:mo> <mml:mi>c</mml:mi> <mml:mi>l</mml:mi> <mml:mover> <mml:mi>ν</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:mrow> </mml:math> decays holding exactly in the large mass limit of heavy quarks. Moreover, we investigate corrections to the sum rule in realistic situations and discuss phenomenological implications.