Hint of a new scalar interaction in LHCb data?

Abstract

We explain recent LHCb measurements of the lepton universality ratios, RD(∗)τ/ℓ≡B(B¯→D(∗)+τ-ν¯τ)B(B¯→D(∗)+ℓ-ν¯ℓ)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R_{D^{(*)}}^{\ au /\\ell }\\equiv \\frac{\\mathcal {B}(\\bar{B} \\rightarrow D^{(*)+} \ au ^- \\bar{\ u }_\ au )}{\\mathcal {B}(\\bar{B} \\rightarrow D^{(*)+}\\ell ^- \\bar{\ u }_\\ell )}$$\\end{document} and R(Λc+)τ/ℓ≡B(Λb→Λc+τ-ν¯τ)B(Λb→Λc+ℓ-ν¯ℓ)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${R(\\Lambda _c^+)}^{\ au /\\ell } \\equiv \\frac{\\mathcal {B}(\\Lambda _b \\rightarrow \\Lambda _c^+ \ au ^- \\bar{\ u }_{\ au })}{\\mathcal {B}(\\Lambda _b \\rightarrow \\Lambda _c^+ \\ell ^- \\bar{\ u }_{\\ell })}$$\\end{document} with ℓ=μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\ell =\\mu $$\\end{document}, via new physics that affects RDτ/ℓ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R_D^{\ au /\\ell }$$\\end{document} and R(Λc+)τ/ℓ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R(\\Lambda _c^+)^{\ au /\\ell }$$\\end{document} but not RD∗τ/ℓ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R_{D^*}^{\ au /\\ell }$$\\end{document}. The scalar operator in the effective theory for new physics is indicated. We find that the forward-backward asymmetry and τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ au $$\\end{document} polarization in B¯→D+τ-ν¯τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\bar{B} \\rightarrow D^+ \ au ^{-} \\bar{\ u }_{\ au }$$\\end{document} and Λb→Λc+τ-ν¯τ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Lambda _b \\rightarrow \\Lambda _c^+ \ au ^- \\bar{\ u }_{\ au }$$\\end{document} decays are significantly affected by the scalar interaction. We construct a simple two Higgs doublet model as a realization of our scenario and consider lepton universality in semileptonic charm and top decays, radiative B decay, B-mixing, and Z→bb¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Z \\rightarrow b \\bar{b}$$\\end{document}.