arXiv subjects
Publications and source records attributed to P. Boyle.
We present results for the QCD matrix elements involved in semi-leptonic decays of B-mesons into pseudo scalar heavy light states. The application of NRQCD heavy quarks allows for quark masses around the physical b-quark. We investigate the dependence of the form factors on the external momenta and looked at the mass dependence at zero recoil. For the first time, results for radially excited decay products are presented.
We present a calculation of the mass of the 1S0 pseudoscalar anti-b c (Bc) state using a non-perturbative measurement from quenched lattice QCD. We find M_Bc = 6.386(9)(98)(15) GeV where the first error is statistical, the second systematic due to the quark mass ambiguities and quenching and the third the systematic error due to the estimation of mass of the eta_b.
We present a calculation of the renormalisation constants for the temporal vector current, $Z_{V_0}$ and spatial axial current, $Z_{A_k}$, to $O(α_s/M)$ for $B\to D$ transitions using the $O(1/M)$ NRQCD action for both $b$ and $c$ quarks evaluated for a large range of mass parameters. Considerations for the renormalisation of the spatial vector current and the temporal axial current are discussed and initial results for a mixed lattice current are presented for the spatial vector current.
We present results of a quenched calculation of the heavy-light and quarkonium spectrum using the tadpole improved clover action. We resolve completely the triplet chi P-states in quarkonium systems, and obtain evidence for fine structure of the heavy-light P-states. Approximate scaling of the hyperfine splittings is observed, producing results that are significantly below experiment.
We use lattice methods to evaluate from first principles the spectrum of hybrid mesons produced by gluonic excitations in quenched QCD with quark masses near the strange quark mass. For the spin-exotic mesons with $J^{PC}=1^{-+},\ 0^{+-}$, and $2^{+-}$ which are not present in the quark model, we determine the lightest state to be $1^{-+}$ with mass of 2.0(2) GeV. Results obtained for orbitally excited mesons are also presented.
A search was conducted for TeV gamma-rays emitted from the direction of the ultra-high energy cosmic ray detected by the Fly's Eye Experiment with E ~ 3 x 10**20 eV. No enhancement was found at a level of 10**-10 gamma/cm**2-sec for E>350 GeV. This upper limit is consistent with theoretical estimates based on topological defects as sources of UHE cosmic rays. An upper limit was also set for the flux of TeV gamma rays from 3C147, the most prominent AGN in the error box.
We use lattice methods to evaluate from first principles the spectrum of hybrid mesons produced by gluonic excitations in quenched QCD with quark masses near the strange quark mass. For the spin-exotic mesons with $J^{PC}=1^{-+},\ 0^{+-}$, and $2^{+-}$ which are not present in the quark model, we determine the lightest state to be $1^{-+}$ with mass of 2.0(2) GeV.
We discuss in general the construction of gauge-invariant non-local meson operators on the lattice. We use such operators to study the $P$- and $D$-wave mesons as well as hybrid mesons in quenched QCD, with quark masses near the strange quark mass. The resulting spectra are compared with experiment for the orbital excitations. For the states produced by gluonic excitations (hybrid mesons) we find evidence of mixing for non-exotic quantum numbers. We give predictions for masses of the spin-exotic hybrid mesons with $J^{PC}=1^{-+},\ 0^{+-}$, and $2^{+-}$.