Measuring V ub and probing SUSY with double ratios of purely leptonic decays of B and D mesons

  • A. G. Akeroyd
  • F. Mahmoudi
Open Access


The experimental prospects for precise measurements of the leptonic decays B u →τν ν, B s μ + μ , Dμν and D s μν/τν are very promising. Double ratios involving four of these decays can be defined in which the dependence on the values of the decay constants is essentially eliminated, thus enabling complementary measurements of the CKM matrix element V ub with a small theoretical error. We quantify the experimental error in a possible future measurement of ∣V ub ∣ using this approach, and show that it is competitive with the anticipated precision from the conventional approaches. Moreover, it is shown that such double ratios can be more effective than the individual leptonic decays as a probe of the parameter space of supersymmetric models. We emphasize that the double ratios have the advantage of using ∣V ub ∣ as an input parameter (for which there is experimental information), while the individual decays have an uncertainty from the decay constants (e.g. \( {f_{{B_s}}} \)), and hence a reliance on theoretical techniques such as lattice QCD.


B-Physics Supersymmetric Standard Model Beyond Standard Model 


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Authors and Affiliations

  1. 1.Department of PhysicsNational Central UniversityJhongliTaiwan
  2. 2.Clermont UniversitéUniversité Blaise Pascal, CNRS/IN2P3, LPCClermont-FerrandFrance

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