Search results for "Leptonic decay"
showing 10 items of 160 documents
Measurement of the charge asymmetry in semileptonic Bs0 decays.
2007
Made available in DSpace on 2022-04-28T20:16:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-04-11 We have performed the first direct measurement of the time-integrated flavor untagged charge asymmetry in semileptonic Bs0 decays ASLs,unt by comparing the decay rate of Bs0→μ+Ds-νX, where Ds- π- and →K+K-, with the charge-conjugate B̄s0 decay rate. This sample was selected from 1.3fb-1 of data collected by the D0 experiment in run II of the Fermilab Tevatron collider. We obtain ASLs,unt=[1.23±0.97(stat)±0. 17(syst)]×10-2. Assuming that Δms/Γ̄s 1, this result can be translated into a measurement of the CP-violating phase in Bs0 mixing: ΔΓs/Δmstan s=[2.45±1.93(stat)±0.35(syst)] ×10-2.…
Relativistic multipole operators for semileptonic weak and electromagnetic nuclear reactions.
1989
We discuss multipole operators that arise in a relativistic analysis ofsemileptonic weak and electromagnetic interactions with nuclei. Thesesingle-particle operators are evaluated between relativistic nucleon boundstates that are solutions to the Dirac equation with potentials of the formproduced by the sigma-..omega.. model. The reduced matrix elements aregiven in terms of easily programmable radial integrals and can be applied to anumber of reactions such as elastic and inelastic electron scattering, realphoton processes, ..beta.. decay, and charged lepton capture as well as moreexotic interactions such as charged and neutral current neutrino reactions. Asa specific example, we calculate …
Search for the DecayB+→K+τ∓μ±
2007
We present a search for the lepton flavor violating decay B+-->K+ tau-/+ mu+/- using 383 x 10;{6} BB[over ] events collected by the BABAR experiment. The branching fraction for this decay can be substantially enhanced in new physics models. The kinematics of the tau from the signal B decay are inferred from the K+, mu, and other B in the event, which is fully reconstructed in one of a variety of hadronic decay modes, allowing the signal B candidate to be fully reconstructed. We observe no excess of events over the expected background and set a limit of B(B+-->K+ tau mu)<7.7 x 10(-5) at 90% confidence level, where the branching fraction is for the sum of the K+ tau- mu+ and K+ tau+mu- final …
Study of the semileptonic decays B→π, D→π and D→K
2006
The semileptonic decay B->pi is studied starting from a simple quark model that takes into account the effect of the B* resonance. A novel, multiply subtracted, Omnes dispersion relation has been implemented to extend the predictions of the quark model to all q^2 values accesible in the physical decay. By comparison to the experimental data, we extract |V_ub|=0.0034 +/- 0.0003(exp.) +/- 0.0007(theory). As a further test of the model, we have also studied D->pi and D->K decays for which we get good agreement with experiment.
Large Impact of the Decay of Niobium Isomers on the Reactor ν¯e Summation Calculations
2019
Even mass neutron-rich niobium isotopes are among the principal contributors to the reactor antineutrino energy spectrum. They are also among the most challenging to measure due to the refractory nature of niobium, and because they exhibit isomeric states lying very close in energy. The beta-intensity distributions of Nb-100gs,Nb-100m and Nb-102gs,Nb-02m beta decays have been determined using the total absorption.-ray spectroscopy technique. The measurements were performed at the upgraded Ion Guide Isotope Separator On-Line facility at the University of Jyvaskyla. Here, the double Penning trap system JYFLTRAP was employed to disentangle the beta decay of the isomeric states. The new data ob…
Measurement of the Semileptonic Branching Ratio ofBs0to an Orbitally ExcitedDs**State:Br(Bs0→Ds1−(2536)μ+νX)
2009
In a data sample of approximately 1.3 fb-1 collected with the D0 detector between 2002 and 2006, the orbitally excited charm state D_s1(2536) has been observed with a measured mass of 2535.7 +/- 0.6 (stat) +/- 0.5 (syst) MeV via the decay mode B0_s -> D_s1(2536) mu nu X. A first measurement is made of the branching ratio product Br(b(bar) -> D_s1(2536) mu nu X).Br(D_s1(2536)->D* K0_S). Assuming that D_s1(2536) production in semileptonic decay is entirely from B0_s, an extraction of the semileptonic branching ratio Br(B0_s -> D_s1(2536) mu nu X) is made.
Measurement of the lifetime of the Bc +- meson in the semileptonic decay channel
2009
Using approximately 1.3 fb-1 of data collected by the D0 detector between 2002 and 2006, we measure the lifetime of the B_c meson in the B_c -> J/psi mu nu X final state. A simultaneous unbinned likelihood fit to the J/\psi+mu invariant mass and lifetime distributions yields a signal of 881 +/- 80 (stat) candidates and a lifetime measurement of \tau(B_c) = 0.448 +0.038 -0.036 (stat) +/- 0.032 (syst) ps.
Measurement of theB0→π−ℓ+νandB+→η(′)ℓ+νbranching fractions, theB0→π−ℓ+νandB+→ηℓ+νform-factor shapes, and determination of|Vub|
2011
We report the results of a study of the exclusive charmless semileptonic decays, B^+ → η^((′))l^+ν and B^0 → π^-l^+ν, undertaken with approximately 464 × 10^6 BB pairs collected at the Υ(4S) resonance with the BABAR detector. The analysis uses events in which the signal B decays are reconstructed with a loose neutrino reconstruction technique. We obtain partial branching fractions for B^+ → ηl^+ν and B^0 → π^-l^+ν decays in three and 12 bins of q^2, respectively, from which we extract the f_+(q^2) form-factor shapes and the total branching fractions B(B^+ → ηl^+ν)=(0.36 ± 0.05_(stat) ± 0.04_(syst))× 10^(-4) and B(B^0 → π^-l^+ν)=(1.42 ± 0.05_(stat) ± 0.07_(syst)) × 10^(-4). We also measure B…
Double beta decays of 124Xe investigated in the QRPA framework
2013
The two-neutrino (2ν2β) and neutrinoless (0ν2β) double beta decays of 124Xe are investigated. Decays to the ground state, , and various 0+ and 2+ excited states in 124Te are considered. The corresponding nuclear matrix elements have been calculated by using the quasiparticle random-phase approximation combined with the multiple-commutator model. G-matrix-based effective nuclear interactions have been used in realistic single-particle model spaces. All possible channels, β+β+, β+EC, and ECEC, are discussed for both the 2ν2β and 0ν2β decays. The associated half-lives are computed, in particular the one corresponding to the resonant neutrinoless double electron capture transition to the 2790.4…
Spin–isospin excitations probed by strong, weak and electro-magnetic interactions
2011
Abstract Gamow–Teller (GT) transitions are the most common weak interaction processes of spin–isospin ( σ τ ) type in atomic nuclei. They are of interest not only in nuclear physics but also in astrophysics; they play an important role in supernovae explosions and nucleosynthesis. The direct study of weak decay processes, however, gives relatively limited information about GT transitions and the states excited via GT transitions (GT states); β decay can only access states at excitation energies lower than the decay Q -value, and neutrino-induced reactions have very small cross-sections. However, one should note that β decay has a direct access to the absolute GT transition strengths B (GT) …