119289904
Closing a loophole in factorization proofs
We address the possibility in factorization proofs that low‐energy collinear gluons can couple to soft gluons.
116621787
Polarization of prompt J/ in proton-proton collisions at RHIC
Within the framework of the nonrelativistic QCD (NRQCD) factorization approach, we compute the polarization of prompt J/{psi} produced at the Brookhaven's Relativistic Heavy-Ion Collider from proton-proton collisions at the center-of-momentum energy {radical}(s)=200 GeV. The perturbative contributions are computed at leading order in the strong coupling constant. The prediction reveals that the color-singlet contribution severely underestimates the PHENIX preliminary data for the differential cross section integrated over the rapidity range |y|<0.35 and its contribution is strongly transversely polarized, which disagrees with the PHENIX preliminary data. After including the color-octet contributions, we find that the NRQCD predictions for both the cross section and polarization over the transverse-momentum range 1.5 GeV<p{sub T}<5 GeV (1.5 GeV<p{sub T}<2 GeV) integrated over the rapidity range |y|<0.35 (1.2<|y|<2.2) agree with the data within errors.
26919092
A Measurement of the Michel Parameters in Leptonic Decays of the Tau
We have measured the spectral shape Michel parameters {rho} and {eta} using leptonic decays of the {tau}, recorded by the CLEO II detector. Assuming e-{mu} universality, we find {rho}{sub e{mu}}= 0.735 {+-} 0.013 {+-} 0.008 and {eta}{sub e{mu}} = 0.015 {+-} 0.061 {+-} 0.062, where the first error is statistical and the second systematic.
125995563
Double quarkonium production at the LHC
124343131
Exclusive spin-2 glueball production associated with J/ψ from e +e- annihilation
118538298
Exclusive heavy quarkonium + γ production from e+e-annihilation into a virtual photon
We compute the cross section for exclusive production of a photon associated with a heavy quarkonium H of charge-conjugation parity C=+1 from e{sup +}e{sup -} annihilation into a virtual photon at the center-of-momentum energy {radical}(s)=10.58 GeV. The nonrelativistic QCD factorization formulas for the differential and total cross sections are obtained at leading order in the strong coupling and in the relative velocity of the heavy quark in the quarkonium rest frame. The predicted cross sections for the S-wave spin-singlet cases are about 80 fb and 50 fb for H={eta}{sub c} and {eta}{sub c}(2S), respectively. Among P-wave spin-triplet charmonia, {chi}{sub c1} has a particularly large cross section of about 14 fb. The cross sections for bottomonium states {eta}{sub b} and {chi}{sub bJ} are about 3 fb. A rough estimate of the background reveals that the signal significances for charmonium processes are sufficiently large enough to be detected with ease with the integrated luminosities available at the present B factories.
126179603
Measurement of |V(ub) / V(cb)| (and |V(ub)|) in exclusive nonleptonic decays within the generalized factorization scheme
Within the generalized factorization scheme, we study extracting $|{V}_{\mathrm{ub}}{/V}_{\mathrm{cb}}|$ by calculating the ratios $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{D}_{s}^{(*)\ensuremath{-}}({\ensuremath{\pi}}^{+},{\ensuremath{\rho}}^{+}))/\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{D}_{s}^{(*)\ensuremath{-}}{D}^{(*)+})$ including penguin effects. The ratios involving the ${B}^{0}\ensuremath{\rightarrow}{D}_{s}^{\ensuremath{-}}{D}^{+}$ mode have considerable penguin corrections $(\ensuremath{\sim}15%$ at the amplitude level), but those involving the ${B}^{0}\ensuremath{\rightarrow}{D}_{s}^{\ensuremath{-}}{D}^{*+}$ mode have relatively small penguin corrections. On the other hand, the ${B}^{0}\ensuremath{\rightarrow}{D}_{s}^{\ensuremath{-}}{D}^{+}$ mode has a smaller form-factor dependence. Therefore, these ratios complement each other in measuring ${V}_{\mathrm{ub}}{/V}_{\mathrm{cb}}.$ The theoretical uncertainty from the hadronic form factors in our method is at the level of 20%, which is comparable to the model dependence uncertainty of about 20% in the measurement of $|{V}_{\mathrm{ub}}{/V}_{\mathrm{cb}}|$ from the exclusive semileptonic B decays. Using the newest upper limit on $\stackrel{\ensuremath{\rightarrow}}{B}{D}_{s}\ensuremath{\pi}$ decay from CLEO, our method sets an upper limit $|{V}_{\mathrm{ub}}{/V}_{\mathrm{cb}}|l0.13$ which is very close to the measured values from the semileptonic B decays.
119214237
The Solar-Type Contact Binary BX Pegasi Revisited
We present the results of new CCD photometry for the contact binary BX Peg, made during three successive months beginning on 2008 September. As do historical light curves, our observations display an O'Connell effect and the November data by themselves indicate clear evidence for very short-term brightness disturbance. For these variations, model spots are applied separately to the two data sets, Group I (Sep.-Oct.) and Group II (Nov.). The former is described by a single cool spot on the secondary photosphere and the latter by a two-spot model with a cool spot on the cool star and a hot one on either star. These are generalized manifestations of the magnetic activity of the binary system. Twenty light-curve timings calculated from Wilson-Devinney code were used for a period study, together with all other minimum epochs. The complex period changes of BX Peg can be sorted into a secular period decrease caused dominantly by angular momentum loss due to magnetic stellar wind braking, a light-travel time (LTT) effect due to the orbit of a low-mass third companion, and a previously unknown short-term oscillation. This last period modulation could be produced either by a second LTT orbit with a period of about 16 yr due to the existence of a fourth body, or by the effect of magnetic activity with a cycle length of about 12 yr.
208868561
A high power liquid hydrogen target for the Mainz A4 parity violation experiment
Abstract We present a new powerful liquid hydrogen target developed for the precise study of parity violating electron scattering on hydrogen and deuterium. This target has been designed to have minimal target density fluctuations under the heat load of a 20 μ A CW 854.3 MeV electron beam without rastering the electron beam. The target cell has a wide aperture for scattered electrons and is axially symmetric around the beam axis. The construction is optimized to intensify heat exchange by a transverse turbulent mixing in the hydrogen stream, which is directed along the electron beam. The target is constructed as a closed loop circulating system cooled by a helium refrigerator. It is operated by a tangential mechanical pump with an optional natural convection mode. The cooling system supports removal of up to 250 W of beam heating removal. Deeply subcooled liquid hydrogen is used to keep the in-beam temperature below the boiling point. The target density fluctuations are found to be at the level of 10 - 3 at a beam current of 20 μ A .
3069819
Test of factorization hypothesis from exclusive nonleptonic B decays
We investigate the possibility of testing the factorization hypothesis in nonleptonic exclusive decays of the B meson. In particular, we consider the nonfactorizable ${B}^{0}\ensuremath{\rightarrow}{D}^{(*)+}{D}_{s}^{(*)\ensuremath{-}}$ modes and ${B}^{0}\ensuremath{\rightarrow}{D}^{(*)+}({\ensuremath{\pi}}^{\ensuremath{-}},{\ensuremath{\rho}}^{\ensuremath{-}})$ known as well-factorizable modes. By taking the ratios $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{D}^{(*)+}{D}_{s}^{(*)\ensuremath{-}})/\mathcal{B}[{B}^{0}\ensuremath{\rightarrow}{D}^{(*)+}({\ensuremath{\pi}}^{\ensuremath{-}},{\ensuremath{\rho}}^{\ensuremath{-}})],$ we find that under the present theoretical and experimental uncertainties there is no evidence for the breakdown of the factorization description for heavy-heavy decays of the B meson.
118428627
Leptogenesis in a seesaw model with Fritzsch-type lepton mass matrices
We investigate how the baryon asymmetry of our Universe via leptogenesis can be achieved within the framework of the seesaw model with Fritzsch-type lepton mass matrices proposed by Fukugita et al. We study the cases with $CP$-violating phases in charged-lepton Yukawa matrix, however, with and without Dirac neutrino Yukawa phases. We consider both flavor-independent and flavor-dependent leptogenesis, and demonstrate how they lead to different amounts of lepton asymmetries in detail. In particular, it is shown that flavor-dependent leptogenesis in this model can be achieved only for very tiny or zero values of $CP$ phases in Dirac neutrino Yukawa matrix at the grand unified theory scale. In addition to the $CP$ phases, for successful leptogenesis in the model it is required that the degeneracy of the heavy Majorana neutrino mass spectrum should be broken and we also show that the breakdown of the degeneracy can be radiatively induced.