Selection rules in three-body B decay from factorization

Extending the dynamics underlying the factorization calculation of two-body decays, we propose simple selection rules for nonresonant three-body B decays. We predict, for instance, that in the Dalitz plot of B^0-->D^0-bar\pi^+\pi^-, practically no events should be found in the corner of E(\pi^+) < \Lambda_{QCD} as compared with the corner of E(\pi^-) < \Lambda_{QCD}. We also predict that there should be very few three-body decay events with a soft meson resonance and two energetic mesons or meson resonances. The selection rules are quite different from the soft pion theorem, since they apply to different kinematical regions. For B^0 -->D^0-bar\pi^+\pi^-, the latter predicts that the decay matrix element vanishes in the zero-four-momentum limit of \pi^+ instead of \pi^-. Since this marked difference from the soft pion theorem is directly related to the issue of short-distance QCD dominance in the FSI of two-body B decays, experimental test of the selection rules will shed light on strong interaction dynamics of B decay.Comment: 12 pages in REVTEX including 3 eps figure

The effects of pre-ignition turbulence by gas jets on the explosion behavior of methane-oxygen mixtures

Most of the previous studies investigating explosion characteristics of combustible mixtures were performed at quiescent state. However, in realistic accidental explosion scenarios, the ignition of the combustible mixture usually occurs under a turbulent environment. In this study, we examine the maximum explosion pressure pmax and explosion time τe of CH4-2O2 mixtures under the pre-ignition turbulence condition in a spherical closed chamber at a room temperature of 298 K. Turbulence is generated using fluidic jet of three different gases (O2, CO2 and N2) and its intensity is controlled by changing the initial pressure of the gas jet pJ0 (i.e., 200 and 500 kPa) and the explosion chamber pressure p0 (i.e., 40 and 60 kPa). The dual effects of turbulence and gas dilution on the explosion behavior of CH4-2O2 mixtures are investigated in detail. The results indicate that by adding O2 into CH4-2O2 mixture at quiescent condition, pmax increases but the rate of overpressure rise is reduced. By introducing turbulence through gas jets into the combustible mixture, the explosion behavior is affected by both the turbulence and gas dilution. With O2 injection, turbulence overall enhances the explosion, but the amount of O2 dilution increases at higher pJ0/p0 and longer jet duration time (tJ0), rendering the mixture to tend toward fuel-lean side and slow down the explosion rate. The present results also demonstrate that the turbulence effect of CO2 is more profound than that of N2 jet. Both pmax and τe are enhanced by CO2 jet turbulence when tJ0 is relative short (tJ0 < 400 ms). However, for longer tJ0, the dominance of CO2 dilution becomes more noticeably than N2 dilution with a longer explosion time τe

A Pragmatic Approach to the Continuum Spectrum in Quasifree Scattering

This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit

Decay Modes of the Nuclear Continuum Excited in Proton-Nucleus Interactions

This work was supported by the National Science Foundation Grant NSF PHY 78-22774 A02 & A03 and by Indiana Universit

Semileptonic and nonleptonic B decays to three charm quarks: B->J/psi (eta_c) D l nu and J/psi (eta_c) D pi

We evaluate the form factors describing the semileptonic decays $\bar{B^0}\to J/\psi (\eta_c) D^+ \ell^- \bar \nu_\ell$, within the framework of a QCD relativistic potential model. This decay is complementary to $\bar{B^0}\to J/\psi (\eta_c) D^+ \pi^-$ in a phase space region where a pion factors out.We estimate the branching ratio for these semileptonic and nonleptonic channels, finding $\mathcal{BR}(\bar{B^0} \to J/\psi (\eta_c) D^+ \ell \nu_\ell) \simeq 10^{-13}$, $\mathcal{BR}(\bar{B^0} \to J/\psi D^+ \pi^-) = 3.1 \times 10^{-8}$ and $\mathcal{BR}(\bar{B^0} \to \eta_c D^+ \pi^-) = 3.5 \times 10^{-8}$.Comment: 14 pages, 4 figure

Pair production of neutralinos via gluon-gluon collisions

The production of a neutralino pair via gluon-gluon fusion is studied in the minimal supersymmetric model(MSSM) at proton-proton colliders. The numerical analysis of their production rates are carried out in the mSUGRA scenario. The results show that this cross section may reach about 80 femto barn for $\tilde{\chi}^{0}_{1}\tilde{\chi}^{0}_{2}$ pair production and 23 femto barn for $\tilde{\chi}^{0}_{2}\tilde{\chi}^{0}_{2}$ pair production with suitable input parameters at the future LHC collider. It shows that this loop mediated process can be competitive with the quark-antiquark annihilation process at the LHC.Comment: LaTex file, l4 pages, 5 EPS figure

Bloch bundles, Marzari-Vanderbilt functional and maximally localized Wannier functions

We consider a periodic Schroedinger operator and the composite Wannier functions corresponding to a relevant family of its Bloch bands, separated by a gap from the rest of the spectrum. We study the associated localization functional introduced by Marzari and Vanderbilt, and we prove some results about the existence and exponential localization of its minimizers, in dimension d < 4. The proof exploits ideas and methods from the theory of harmonic maps between Riemannian manifolds.Comment: 37 pages, no figures. V2: the appendix has been completely rewritten. V3: final version, to appear in Commun. Math. Physic

Pair Production of the Lightest Chargino via Gluon-Gluon Collisions

The production of the lightest chargino pair from gluon-gluon fusion is studied in the minimal supersymmetric model(MSSM) at proton-proton colliders. We find that with the chosen parameters, the production rate of the subprocess can be over 2.7 femto barn when the chargino is higgsino-like, and the corresponding total cross section in proton-proton collider can reach 56 femto barn at the LHC in the CP-conserving MSSM. It shows that this loop mediated subprocess can be competitive with the standard Drell-Yan subprocess in proton-proton colliders, especially at the LHC. Furthermore, our calculation shows it would be possible to extract information about some CP-violating phase parameters, if we collected enough chargino pair events.Comment: 39 pages, LaTex, 8 figure

Deviation of Atmospheric Mixing from Maximal and Structure in the Leptonic Flavor Sector

I attempt to quantify how far from maximal one should expect the atmospheric mixing angle to be given a neutrino mass-matrix that leads, at zeroth order, to a nu_3 mass-eigenstate that is 0% nu_e, 50% nu_mu, and 50% nu_tau. This is done by assuming that the solar mass-squared difference is induced by an "anarchical" first order perturbation, an approach than can naturally lead to experimentally allowed values for all oscillation parameters. In particular, both |cos 2theta_atm| (the measure for the deviation of atmospheric mixing from maximal) and |U_e3| are of order sqrt(Delta m^2_sol/Delta m^2_atm) in the case of a normal neutrino mass-hierarchy, or of order Delta m^2_sol/Delta m^2_atm in the case of an inverted one. Hence, if any of the textures analyzed here has anything to do with reality, next-generation neutrino experiments can see a nonzero cos 2theta_atm in the case of a normal mass-hierarchy, while in the case of an inverted mass-hierarchy only neutrino factories should be able to see a deviation of sin^2 2theta_atm from 1.Comment: 12 pages, no figures, references and acknowledgments adde