1,311 research outputs found
Lattice QCD Study of the Pentaquark Baryons
We study the spin hadronic state in quenched lattice QCD to search
for a possible pentaquark resonance. Simulations are carried out on
, , and lattices
at =5.7 at the quenched level with the standard plaquette gauge action
and Wilson quark action. We adopt two independent operators with I=0 and
to construct a correlation matrix. After the
diagonalization of the correlation matrix, we successfully obtain the energies
of the ground-state and the 1st excited-state in this channel. The volume
dependence of the energies suggests the existence of a possible resonance state
slightly above the NK threshold in I=0 and channel.Comment: Talk given at the International Workshop on PENTAQUARK04, SPring-8,
Japan, 20-23 July 2004; 7 pages, 3 figure
Precision study of B^* B\pi coupling for the static heavy-light meson
We compute the B^*B\pi coupling \hat{g}_{\infty} for static heavy-light meson
using all-to-all propagators. It is shown that low-mode averaging with 100
low-lying eigenmodes indeed improves the signal for the 2-point and 3-point
functions for heavy-light meson significantly. Our study suggests that the
all-to-all propagator will be a very efficient method for high precision
computation of the B^*B\pi coupling especially in unquenched QCD where the
number of configurations is limited.Comment: 30 pages, 25 figures, typos correcte
Constraints on a New Light Spin-One Particle from Rare b -> s Transitions
The anomalously large like-sign dimuon charge asymmetry in semileptonic
b-hadron decays recently measured by the D0 Collaboration may be hinting at the
presence of CP-violating new physics in the mixing of B_s mesons. It has been
suggested that the effect of a nonstandard spin-1 particle lighter than the b
quark with flavor-changing couplings to b and s quarks can reproduce the D0
result within its one-sigma range. Here we explore the possibility that the new
particle also couples to charged leptons l=e,mu and thus contributes to rare b
-> s processes involving the leptons. We consider in particular constraints on
its couplings from existing experimental data on the inclusive B -> X_s l^+ l^-
and exclusive B -> K^{(*)} l^+ l^- decays, as well as the anomalous magnetic
moments of the leptons. We find that there is parameter space of the particle
that is allowed by the current data. Future measurements of these B transitions
and rare decays of the B_s meson, such as B_s -> (phi,eta,eta') l^+ l^- and B_s
-> l^+ l^-, at LHCb and next-generation B factories can probe its presence or
couplings more stringently.Comment: 19 pages, 5 figure
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