1,492 research outputs found
Radiative decays: a new flavour filter
Radiative decays of the orbital excitations of the ,
and to the scalars , and are shown to
provide a flavour filter, clarifying the extent of glueball mixing in the
scalar states. A complementary approach to the latter is provided by the
radiative decays of the scalar mesons to the ground-state vectors ,
and . Discrimination among different mixing scenarios is strong.Comment: 12 pages, 1 table, 0 figure
Heavy meson masses and decay constants from relativistic heavy quarks in full lattice QCD
We determine masses and decay constants of heavy-heavy and heavy-charm
pseudoscalar mesons as a function of heavy quark mass using a fully
relativistic formalism known as Highly Improved Staggered Quarks for the heavy
quark. We are able to cover the region from the charm quark mass to the bottom
quark mass using MILC ensembles with lattice spacing values from 0.15 fm down
to 0.044 fm. We obtain f_{B_c} = 0.427(6) GeV; m_{B_c} = 6.285(10) GeV and
f_{\eta_b} = 0.667(6) GeV. Our value for f_{\eta_b} is within a few percent of
f_{\Upsilon} confirming that spin effects are surprisingly small for heavyonium
decay constants. Our value for f_{B_c} is significantly lower than potential
model values being used to estimate production rates at the LHC. We discuss the
changing physical heavy-quark mass dependence of decay constants from
heavy-heavy through heavy-charm to heavy-strange mesons. A comparison between
the three different systems confirms that the B_c system behaves in some ways
more like a heavy-light system than a heavy-heavy one. Finally we summarise
current results on decay constants of gold-plated mesons.Comment: 16 pages, 12 figure
Monomer diffusion rates in photopolymer material: Part I. Low spatial frequency holographic gratings: reply
In [1,2] an error (by a factor of 1000) in the diffusion rate of monomer in a photopolymer material used by the
authors of [3], is presented. In [3] no errors are identified in our analysis and our physical evidence is not addressed.
It is implied that our model and our results are disproven by the results in the papers referenced in
[3]. In fact these papers do not provide any such quantitative evidence. The observations made regarding the significance
of the authors’ contributions, in particular the validity of their model and the practical importance of
their material are also discussed. © 2012 Optical Society of Americ
A multibeam atom laser: coherent atom beam splitting from a single far detuned laser
We report the experimental realisation of a multibeam atom laser. A single
continuous atom laser is outcoupled from a Bose-Einstein condensate (BEC) via
an optical Raman transition. The atom laser is subsequently split into up to
five atomic beams with slightly different momenta, resulting in multiple,
nearly co-propagating, coherent beams which could be of use in interferometric
experiments. The splitting process itself is a novel realization of Bragg
diffraction, driven by each of the optical Raman laser beams independently.
This presents a significantly simpler implementation of an atomic beam
splitter, one of the main elements of coherent atom optics
Baryon Masses in Chiral Perturbation Theory with Infrared Regularization
The baryon masses are examined in SU(3) chiral perturbation theory to third
order using the recently proposed infrared regularization scheme. Fourth order
is estimated by evaluating the dominant diagram. With this regularization the
magnitude of the loop integrals is reduced so that the convergence of the
series appears to be better than in the heavy baryon approach.Comment: The original third order calculation is supplemented by an estimate
of fourth order using just the dominant diagram. The convergence still
appears to be better than in the heavy baryon approach. To be published in
Phys. Rev. C. 15 pages latex, 2 postscript figure
The eta' in baryon chiral perturbation theory
We include in a systematic way the eta' in baryon chiral perturbation theory.
The most general relativistic effective Lagrangian describing the interaction
of the lowest lying baryon octet with the Goldstone boson octet and the eta' is
presented up to linear order in the derivative expansion and its heavy baryon
limit is obtained. As explicit examples, we calculate the baryon masses and the
pi N sigma-term up to one-loop order in the heavy baryon formulation. A
systematic expansion in the meson masses is possible, and appearing divergences
are renormalized.Comment: 16 pages, 2 figure
Nucleon Resonances and Quark Structure
A pedagogical review of the past 50 years of study of resonances, leading to
our understanding of the quark content of baryons and mesons. The level of this
review is intended for undergraduates or first-year graduate students. Topics
covered include: the quark structure of the proton as revealed through deep
inelastic scattering; structure functions and what they reveal about proton
structure; and prospects for further studies with new and upgraded facilities,
particularly a proposed electron-ion collider.Comment: 21 pages, 15 figure
Exotic meson spectroscopy from the clover action at beta = 5.85 and 6.15
We repeat our original simulations of the hybrid meson spectrum using the
clover action, as a check on lattice artifacts. Our results for the 1-+ masses
do not substantially change. We present preliminary results for the wave
function of the 1-+ state in Coulomb gauge.Comment: LATTICE98(spectrum) 3 latex pages and two postscript figures.
Contribution to lattice 9
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