The Λ b → Λ ? 1520 → N K ˉ ? + ? ? documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ {Lambda}_bo {Lambda}^{st }(1520)left(o Noverline{K}ight){mathrm{ell}}^{+}{mathrm{ell}}^{-} $$end{document} decay at low-recoil in HQET

摘要

A bstract In this paper we discuss the Standard Model and new physics sensitivity of the Λ b → Λ ? 1520 → N K ˉ ? + ? ? documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ {Lambda}_bo {Lambda}^{st }(1520)left(o Noverline{K}ight){mathrm{ell}}^{+}{mathrm{ell}}^{-} $$end{document} decay at low-recoil, where ? ~( ± )are massive leptons and N K ˉ = pK ? n K ˉ 0 documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ Noverline{K}=left{{pK}^{-},n{overline{K}}^0ight} $$end{document} . We provide a full angular distribution with a set of operators that includes the Standard Model operators and their chirality flipped counterparts, and new scalar and pseudo-scalar operators. The resulting angular distribution allows us to construct observables that we study in the Standard Model and in model-independent new physics scenarios. To reduce the hadronic effects emanating from the Λ_( b ) → Λ~(*)(1520) transition form factors, we exploit the Heavy Quark Effective theory framework valid at low Λ~( ? )(1520) recoil, i.e., large dilepton invariant mass squared q 2 ～ O m b 2 documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ {q}^2sim mathcal{O}left({m}_b^2ight) $$end{document} . Working to the leading order in 1 /m _( b )and including O α s documentclass[12pt]{minimal} usepackage{amsmath} usepackage{wasysym} usepackage{amsfonts} usepackage{amssymb} usepackage{amsbsy} usepackage{mathrsfs} usepackage{upgreek} setlength{oddsidemargin}{-69pt} egin{document}$$ mathcal{O}left({lpha}_sight) $$end{document} corrections, we compute the ‘improved Isgur-Wise relations’ between the form factors. The relations correlate the form factors and thereby allow the description of this decay at the low-recoil region with a smaller number of independent form factors.