Model-independent bounds on R(J/ψ)

• Main Authors: Thomas D. Cohen, Henry Lamm, Richard F. Lebed
• Format: Article
• Language: English
• Published: SpringerOpen 2018-09-01
• Series: Journal of High Energy Physics
• Subjects: Heavy Quark Physics; Quark Masses and SM Parameters; Lattice QCD
• Online Access: http://link.springer.com/article/10.1007/JHEP09(2018)168

Abstract We present a model-independent bound on RJ/ψ≡ℬℛBC+→J/ψτ+ντ/ℬℛBC+→J/ψµ+νµ $$ R\left(J/\psi \right)\equiv \mathrm{\mathcal{B}}\mathrm{\mathcal{R}}\left({B}_C^{+}\to J/\psi {\tau}^{+}{\nu}_{\tau}\right)/\mathrm{\mathcal{B}}\mathrm{\mathcal{R}}\left({B}_C^{+}\to J/\psi {\mu}^{+}{\nu}_{\mu}\right) $$. This bound is constructed by constraining the form factors through a combination of dispersive relations, heavy-quark relations at zero-recoil, and the limited existing determinations from lattice QCD. The resulting 95% confidence-level bound, 0.20 ≤ R(J/ψ) ≤ 0.39, agrees with the recent LHCb result at 1.3σ, and rules out some previously suggested model form factors.