In Pursuit of New Physics with B_s Decays

The presence of a sizeable CP-violating phase in B_s^0-B_s^0-bar mixing would be an unambiguous signal of physics beyond the Standard Model. We analyse various possibilities to detect such a new phase considering both tagged and untagged decays. The effects of a sizeable width difference Delta Gamma between the B_s mass eigenstates, on which the untagged analyses rely, are included in all formulae. A novel method to find this phase from simple measurements of lifetimes and branching ratios in untagged decays is proposed. This method does not involve two-exponential fits, which require much larger statistics. For the tagged decays, an outstanding role is played by the observables of the time-dependent angular distribution of the B_s -> J/psi [-> l^+ l^-] \phi [-> K^+K^-] decay products. We list the formulae needed for the angular analysis in the presence of both a new CP-violating phase and a sizeable Delta Gamma, and propose methods to remove a remaining discrete ambiguity in the new phase. This phase can therefore be determined in an unambiguous way.Comment: minor changes, lattice prediction of Delta Gamma updated, appears in PR

Model-independent constraints on Delta F=2 operators and the scale of New Physics

We update the constraints on new-physics contributions to Delta F=2 processes from the generalized unitarity triangle analysis, including the most recent experimental developments. Based on these constraints, we derive upper bounds on the coefficients of the most general Delta F=2 effective Hamiltonian. These upper bounds can be translated into lower bounds on the scale of new physics that contributes to these low-energy effective interactions. We point out that, due to the enhancement in the renormalization group evolution and in the matrix elements, the coefficients of non-standard operators are much more constrained than the coefficient of the operator present in the Standard Model. Therefore, the scale of new physics in models that generate new Delta F=2 operators, such as next-to-minimal flavour violation, has to be much higher than the scale of minimal flavour violation, and it most probably lies beyond the reach of direct searches at the LHC.Comment: 32 pages, 11 figures, 6 tables. v2: error in the implementation of D0 untagged Bs->J/Psi phi correlation matrix corrected. Improved presentation of the results and discussion of ambiguities in untagged Bs->J/Psi phi. Results for NP in Bs oscillations changed. Final version to appear in JHE

Averages of b-hadron, c-hadron, and tau-lepton properties as of 2018 Heavy Flavor Averaging Group (HFLAV)

This paper reports world averages of measurements of b-hadron, c-hadron, and τ -lepton properties obtained by the Heavy Flavour Averaging Group using results available through September 2018. In rare cases, significant results obtained several months later are also used. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, C P violation parameters, parameters of semileptonic decays, and Cabibbo–Kobayashi–Maskawa matrix elements

Bestimmung einer oberen Schranke fuer (#DELTA##GAMMA#)/(#GAMMA#) in the #BETA#_s"0 - anti #BETA#_s"0-System und Einschraenkung der CKM-Matrix

Available from TIB Hannover: RA 2316(99-01) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

A new method of measuring (#DELTA##GAMMA#)/(#GAMMA#) in the #BETA#_s"0 -anti #BETA#_s"0 system

A new way to measure (#DELTA##GAMMA#/#GAMMA#) in the B_s"0-B_s"0 System based on a comparison of the measured B_s"0 and B_d"0 lifetimes is introduced. This allows to use data from all the experiments simultaneously. An upper limit of (#DELTA##GAMMA#/#GAMMA#)#<=#0.24 at 95% CL can be given. This is below the theoretical upper limit of 0.27. (orig.)8 refs.SIGLEAvailable from TIB Hannover: RA 2316(98-21) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman