Constraints on R-parity violating couplings from lepton universality

We analyze the one loop corrections to leptonic W and Z decays in an R-parity violating extension to the Minimal Supersymmetric Standard Model (MSSM). We find that lepton universality violation in the Z line-shape variables alone would strengthen the bounds on the magnitudes of the lambda' couplings, but a global fit on all data leaves the bounds virtually unchanged at |lambda'_{33k}| < 0.42 and |lambda'_{23k}| < 0.50 at the 2 sigma level. Bounds from W decays are less stringent: |lambda'_{33k}| < 2.4 at 2 sigma, as a consequence of the weaker Fermilab experimental bounds on lepton universality violation in W decays. We also point out the potential of constraining R-parity violating couplings from the measurement of the Upsilon invisible width.Comment: 26pages, 8 postscript figures, REVTeX. Updated references. Typos correcte

Constraints on R-parity violating couplings from LEP/SLD hadronic observables

We analyze the one loop corrections to hadronic Z decays in an R-parity violating extension to the Minimal Supersymmetric Standard Model (MSSM). Performing a global fit to all the hadronic observables at the Z-peak, we obtain stringent constraints on the R-violating couplings constants lambda' and lambda''. As a result of the strong constraints from the b asymmetry parameters A_b and A_FB(b), we find that the couplings lambda'{i31}, lambda'{i32}, and lambda''{321} are ruled out at the 1 sigma level, and that lambda'{i33} and lambda''{33i} are ruled out at the 2 sigma level. We also obtain Bayesian confidence limits for the R-violating couplings.Comment: 30 pages, 19 postscript figures, REVTeX, new section 8 on Bayesian confidence limits adde

ft Value of O14 and the Universality of the Fermi Interaction

The conserved-vector-current theory of the strangeness-conserving weak decays predicts that GV, the vector coupling constant in nuclear beta decay, should be equal to Gμ, the coupling constant in the muon decay. To make possible a more precise comparison of GV and Gμ, the ft value of O14 has been remeasured. The endpoint energy of the positron decay has been determined by measuring the Q values of the reactions C12(He3, n)O14 and C12(He3, p)N14* (2.311-MeV state), using the same techniques and equipment where possible in order to minimize the uncertainty in the difference of the Q values. The results of these measurements are Qn=-1148.8±0.6 keV and Qp=2468.4±1.0 keV, which yield Emax(β+)=1812.6±1.4 keV, all energies relative to the Li7(p, n)Be7 threshold assumed as 1880.7±0.4 keV. The half-life of O14 has also been remeasured as 71.00±0.13 sec, which implies a partial half-life of 71.43±0.15 sec for the transition to the 2.311-MeV state of N14. Averaged with the recent half-life measurement of Hendrie and Gerhart, we obtain an ft value of 3075±10 sec for the O14 decay, after correcting for nuclear form factors, electron screening, and K-capture competition. With the radiative corrections of Kinoshita and Sirlin, the value obtained for GV is (1.4025±0.0022)×10^-49 erg-cm^3, where the quoted error is experimental in origin. This is to be compared with the value computed from recent muon decay measurements, Gμ=(1.4312±0.0011)×10^-49 erg-cm^3, which is (2.0±0.2)% larger. As there appear to be several possible theoretical explanations for this small discrepancy, the present results are consistent with the conserved-vector-current hypothesis

Searching for Anomalous Weak Couplings of Heavy Flavors at the SLC and LEP

The existence of anomalous electric($\tilde \kappa$) and/or magnetic($\kappa$) dipole moment couplings between the heavy flavor fermions ($c,b,\tau$) and the $Z$ boson can cause significant shifts in the values of several electroweak observables currently being probed at both the SLC and LEP. Using the good agreement between existing data and the predictions of the Standard Model we obtain strict bounds on the possible strength of these new interactions for all of the heavy flavors. The decay $Z\rightarrow b\bar b$, however, provides some possible hint of new physics. The corresponding anomalous couplings of $\tau$'s to photons is briefly examined.Comment: 21 pages, 14 figs(available on request), LaTex, SLAC-PUB-667

Decays of Scalar and Pseudoscalar Higgs Bosons into Fermions: Two-loop QCD Corrections to the Higgs-Quark-Antiquark Amplitude

As a first step in the aim of arriving at a differential description of neutral Higgs boson decays into heavy quarks, $h \to Q {\bar Q}X$, to second order in the QCD coupling $\alpha_S$, we have computed the $hQ{\bar Q}$ amplitude at the two-loop level in QCD for a general neutral Higgs boson which has both scalar and pseudoscalar couplings to quarks. This amplitude is given in terms of a scalar and a pseudoscalar vertex form factor, for which we present closed analytic expressions in terms of one-dimensional harmonic polylogarithms of maximum weight 4. The results hold for arbitrary four-momentum squared, $q^2$, of the Higgs boson and of the heavy quark mass, $m$. Moreover we derive the approximate expressions of these form factors near threshold and in the asymptotic regime $m^2/q^2 \ll 1$.Comment: 56 pages, 2 figure

SANC integrator in the progress: QCD and EW contributions

Modules and packages for the one-loop calculations at partonic level represent the first level of SANC output computer product. The next level represents Monte Carlo integrator mcsanc, realizing fully differential hadron level calculations (convolution with PDF) for the HEP processes at LHC. In this paper we describe the implementation into the framework mcsanc first set of processes: DY NC, DY CC, ff->HW(Z) and single top production. Both EW and QCD NLO corrections are taken into account. A comparison of SANC results with those existing in the world literature is given

Inverse bremsstrahlung contributions to Drell-Yan like processes

The contribution of the sub-process $\gamma q \to q' l_1\bar{l}_2$ in hadron-hadron interactions is considered. It is a part of one-loop electroweak radiative corrections for the Drell-Yan production of lepton pairs at hadron colliders. It is shown that this contribution should be taken into account aiming at the 1% accuracy of the Drell-Yan process theoretical description. Both the neutral and charged current cases are evaluated. Numerical results are presented for typical conditions of LHC experiments.Comment: 11 pages, 8 figure