1,327 research outputs found
Energies of B_s meson excited states - a lattice study
This is a follow-up to our earlier work on the energies and radial
distributions of heavy-light mesons. The heavy quark is taken to be static
(infinitely heavy) and the light quark has a mass about that of the strange
quark. We now concentrate on the energies of the excited states with higher
angular momentum and with a radial node. A new improvement is the use of
hypercubic blocking in the time direction.
The calculation is carried out with dynamical fermions on a 16 cubed times 32
lattice with a lattice spacing approximately 0.1 fm generated using a
non-perturbatively improved clover action.
In nature the closest equivalent of this heavy-light system is the B_s meson,
which allows us to compare our lattice calculations to experimental results
(where available) or to give a prediction where the excited states,
particularly P-wave states, should lie. We pay special attention to the
spin-orbit splitting, to see which one of the states (for a given angular
momentum L) has the lower energy. An attempt is made to understand these
results in terms of the Dirac equation.Comment: 35 pages. v3: Data from two new lattices added. New results in
several chapter
Generalized Kinetic Theory of Electrons and Phonons
A Generalized Kinetic Theory was proposed in order to have the possibility to
treat particles which obey a very general statistics. By adopting the same
approach, we generalize here the Kinetic Theory of electrons and phonons.
Equilibrium solutions and their stability are investigated.Comment: Proceedings of the International School and Workshop on Nonextensive
Thermodynamics and Physical Applications, NEXT 2001, 23-30 May 2001, Cagliari
(Italy) (To appear in Physica A
P-wave Radial distributions of a Heavy-light meson on a lattice
This is a follow-up to our earlier work for the charge (vector) and matter
(scalar) distributions for S-wave states in a heavy-light meson, where the
heavy quark is static and the light quark has a mass about that of the strange
quark. The calculation is again carried out with dynamical fermions on a
16^3x24 lattice with a lattice spacing of about 0.14 fm. It is shown that
several features of the S- and P-wave distributions are in qualitative
agreement with what one expects from a simple one-body Dirac equation
interpretation.Comment: 5 pages, 2 figures, Quark Confinement and the Hadron Spectrum VI,
Sardinia, Italy, September, 200
Conditions for waveguide decoupling in square-lattice photonic crystals
We study coupling and decoupling of parallel waveguides in two-dimensional
square-lattice photonic crystals. We show that the waveguide coupling is
prohibited at some wavelengths when there is an odd number of rows between the
waveguides. In contrast, decoupling does not take place when there is even
number of rows between the waveguides. Decoupling can be used to avoid cross
talk between adjacent waveguides.Comment: 6 pages, 2 figure
The Charge and Matter radial distributions of Heavy-Light mesons calculated on a lattice
For a heavy-light meson with a static heavy quark, we can explore the light
quark distribution. The charge and matter radial distributions of these
heavy-light mesons are measured on a 16^3 * 24 lattice at beta=5.7 and a
hopping parameter corresponding to a light quark mass about that of the strange
quark. Both distributions can be well fitted up to 4 lattice spacings (r approx
0.7 fm) with the exponential form w_i^2(r), where w_i(r)=A exp(-r/r_i). For the
charge(c) and matter(m) distributions r_c approx 0.32(2) fm and r_m approx
0.24(2) fm. We also discuss the normalisation of the total charge and matter
integrated over all space, finding 1.30(5) and 0.4(1) respectively.Comment: 31 pages including 7 ps figure
Pair formation and collapse in imbalanced Fermion populations with unequal masses
We present an exact Quantum Monte Carlo study of the effect of unequal masses
on pair formation in Fermionic systems with population imbalance loaded into
optical lattices. We have considered three forms of the attractive interaction
and find in all cases that the system is unstable and collapses as the mass
difference increases and that the ground state becomes an inhomogeneous
collapsed state. We also address the question of canonical vs grand canonical
ensemble and its role, if any, in stabilizing certain phases
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