Search results for "decay"
showing 10 items of 2087 documents
Search for the reactionse+e−→μ+τ−ande+e−→e+τ−
2007
We report on a search for the lepton- flavor- violating processes e(+) e(-) -> mu(+) tau(-) and e(+) e(-) -> e(+) tau(-). The data sample corresponds to an integrated luminosity of 211 fb(-1) recorded by the BABAR experiment at the SLAC PEP-II asymmetric-energy B Factory at a center-of-mass energy of root s = 10.58 GeV. We find no evidence for a signal and set the 90% confidence level upper limits on the cross sections to be sigma (mu tau) < 3.8 fb and sigma(e tau) < 9.2 fb. The ratio of the cross sections with respect to the dimuon cross section are measured to be sigma (mu tau)/sigma (mu mu) < 3.4 X 10(-6) and sigma (e tau)/sigma (mu mu) < 8.2 X 10(-6).
Leptonic decays of the D-s meson
2002
The purely leptonic decays Ds -> tau nu and Ds -> mu nu are studied in a sample of four million hadronic Z decays collected with the ALEPH detector at the LEP e+e- collider from 1991 to 1995. The branching fractions are extracted from a combination of two analyses, one optimized to select Ds -> tau nu decays with tau -> e nu nubar or mu nu nubar, and the other optimized for Ds-> mu nu decays. The results are used to evaluate the Ds decay constant, within the Standard Model: fDs = [285 +- 19(stat) +- 40 (syst)] MeV
Measurement of double charmonium production ine+e−annihilations ats=10.6 GeV
2005
We study $e^+e^-\to J/\psi c\bar{c}$ by measuring the invariant mass distribution recoiling against fully reconstructed $J/\psi$ decays, using 124 fb$^{-1}$ of data collected with a center-of-mass energy of 10.6 GeV with the $BaBar$ detector. We observe signals for $\eta_c(1S)$, $\chi_{c0}$, and $\eta_c(2S)$ in the recoil mass distribution, thus confirming previous measurements. We measure $\sigma(e^+e^-\to J/\psi+c\bar{c}) {\cal B} (c\bar{c} \to >2 charged)$ to be $17.6\pm2.8 (stat)^{+1.5}_{-2.1}(syst)$ fb, $ 10.3\pm2.5(stat)^{+1.4}_{-1.8}syst)$ fb, and $16.4\pm3.7(stat)^{+2.4}_{-3.0}(syst)$ fb with $c\bar{c}=\eta_c(1S)$, $\chi_{c0}$, and $\eta_c(2S)$, respectively.
Measurement of decay amplitudes ofB→J/ψK*,ψ(2S)K*, andχc1K*with an angular analysis
2007
We perform the first three-dimensional measurement of the amplitudes of B→ψ(2S)K* and B→χc1K* decays and update our previous measurement for B→J/ψK*. We use a data sample collected with the BABAR detector at the PEP-II storage ring, corresponding to 232×106 BB pairs. The longitudinal polarization of decays involving a JPC=1++ χc1 meson is found to be larger than that with a 1 - J/ψ or ψ(2S) meson. No direct CP-violating charge asymmetry is observed. © 2007 The American Physical Society.
Low-lying even parity meson resonances and spin-flavor symmetry
2010
A study is presented of the $s-$wave meson-meson interactions involving members of the $\rho-$nonet and of the $\pi-$octet. The starting point is an SU(6) spin-flavor extension of the SU(3) flavor Weinberg-Tomozawa Lagrangian. SU(6) symmetry breaking terms are then included to account for the physical meson masses and decay constants, while preserving partial conservation of the axial current in the light pseudoscalar sector. Next, the $T-$matrix amplitudes are obtained by solving the Bethe Salpeter equation in coupled-channel with the kernel built from the above interactions. The poles found on the first and second Riemann sheets of the amplitudes are identified with their possible Particl…
Enhanced nonlocal power corrections to theB¯→Xsγdecay rate
2007
A new class of enhanced nonperturbative corrections to the inclusive $\overline{B}\ensuremath{\rightarrow}{X}_{s}\ensuremath{\gamma}$ decay rate is identified, which contribute first at order $\ensuremath{\Lambda}/{m}_{b}$ in the heavy-quark expansion and cannot be described using a local operator product expansion. Instead, these effects are described in terms of hadronic matrix elements of nonlocal operators with component fields separated by lightlike distances. They contribute to the high-energy part of the photon-energy spectrum but do not reduce to local operators when an integral over energy is taken to obtain the total inclusive decay rate. The dominant corrections depend on the fla…
Radiative decays of theY(3940),Z(3930), and theX(4160)as dynamically generated resonances
2011
We study the radiative decay properties of the charmoniumlike $X$, $Y$, and $Z$ mesons generated dynamically from vector-meson--vector-meson interaction in the framework of a unitarized hidden-gauge formalism. In the present work, we calculate the one- and two-photon decay widths of the hidden-charm $Y(3940)$, $Z(3930)$ [or $X(3915)$], and $X(4160)$ mesons in the framework of the vector-meson dominance formalism. We obtain good agreement with the experiment in case of the two-photon width of the $X(3915)$, which we associate to the ${2}^{+}$ resonance that we find at 3922 MeV. However, in view of discrepancies with a different approach that also considers the resonances as molecular states,…
Predictions for η→ηπ+π− producing f0(500), f0(980) and a0(980)
2017
Abstract We perform calculations for the η c → η π + π − decay using elements of SU(3) symmetry to see the weight of different trios of pseudoscalars produced in this decay, prior to the final state interaction of the mesons. After that, the interaction of pairs of mesons, leading finally to η π + π − , is done using the chiral unitary approach. We evaluate the π + π − and πη mass distributions and find large and clear signals for f 0 ( 500 ) , f 0 ( 980 ) and a 0 ( 980 ) excitation. The reaction is similar to the χ c 1 → η π + π − , which has been recently measured at BESIII and its implementation and comparison with these predictions will be very valuable to shed light on the nature of th…
Search forCPViolation in the DecaysD0→K−K+andD0→π−π+
2008
We report a search for CP violation in the decay modes D±→KS0K±, Ds±→KS0K±, and Ds±→KS0π± using a data set corresponding to an integrated luminosity of 469 fb-1 collected with the BABAR detector at the PEP-II asymmetric energy e+e- storage rings. The decay rate CP asymmetries, ACP, are determined to be (+0.13±0.36(stat)±0.25(syst))%, (-0.05±0.23(stat)±0.24(syst))%, and (+0.6±2.0(stat)±0.3(syst))%, respectively. These measurements are consistent with zero, and also with the Standard Model prediction [(-0.332±0.006)% for the D±→KS0K± and Ds±→KS0K± modes, and (+0.332±0.006)% for the Ds±→KS0π± mode]. They are the most precise determinations to date.
Decay of vector-vector resonances into $\gamma$ and a pseudoscalar meson
2010
We study the decay of dynamically generated resonances from the interaction of two vectors into a $\ensuremath{\gamma}$ and a pseudoscalar meson. The dynamics requires anomalous terms involving vertices with two vectors and a pseudoscalar, which renders it special. We compare our result with data on ${K}_{2}^{*+}(1430)\ensuremath{\rightarrow}{K}^{+}\ensuremath{\gamma}$ and ${K}_{2}^{*0}(1430)\ensuremath{\rightarrow}{K}^{0}\ensuremath{\gamma}$ and find a good agreement with the data for the ${K}_{2}^{*+}(1430)$ case and a width considerably smaller than the upper bound measured for the ${K}_{2}^{*0}(1430)$ meson. We also investigate the decay into ${\ensuremath{\pi}}^{+}\ensuremath{\gamma}$ …