82 research outputs found
Lattice study on and X(3872)
Properties of charmonium are investigated in quenched
lattice QCD. The mass of is determined to be 3.80(3) GeV, which is
close to the mass of -wave charmonium and in agreement with
quark model predictions. The transition width of
is also obtained with a value keV. Since the possible
assignment to X(3872) has not been ruled out by experiments, our results help
to clarify the nature of X(3872).Comment: 15 pages, 8 figures. typos, grammatical errors and some references
corrected, redundant discussions deleted, conclusion does not change.
published versio
Proton Mass Decomposition from the QCD Energy Momentum Tensor
We report results on the proton mass decomposition and also on related quark
and glue momentum fractions. The results are based on overlap valence fermions
on four ensembles of DWF configurations with three lattice spacings
and three volumes, and several pion masses including the physical pion mass.
With fully non-perturbative renormalization (and universal normalization on
both quark and gluon), we find that the quark energy and glue field energy
contribute 33(4)(4)\% and 37(5)(4)\% respectively in the scheme
at GeV. A quarter of the trace anomaly gives a 23(1)(1)\%
contribution to the proton mass based on the sum rule, given 9(2)(1)\%
contribution from the and quark scalar condensates. The and
glue momentum fractions in the scheme are in good agreement
with global analyses at GeV.Comment: 10 pages, 6 figure
Meson Mass Decomposition
Hadron masses can be decomposed as a sum of components which are defined
through hadronic matrix elements of QCD operators. The components consist of
the quark mass term, the quark energy term, the glue energy term and the trace
anomaly term. We calculate these components of mesons with lattice QCD for the
first time. The calculation is carried out with overlap fermion on flavor
domain-wall fermion gauge configurations. We confirm that of the
light pion mass comes from the quark mass and comes from the quark
energy, whereas, the contributions are found to be the other way around for the
mass. The combined glue components contribute for both
mesons. It is interesting to observe that the quark mass contribution to the
mass of the vector meson is almost linear in quark mass over a large quark mass
region below the charm quark mass. For heavy mesons, the quark mass term
dominates the masses, while the contribution from the glue components is about
MeV for the heavy pseudoscalar and vector mesons. The charmonium
hyperfine splitting is found to be dominated by the quark energy term which is
consistent with the quark potential model.Comment: 7 Pages, 4 figures, contribution to the 32nd International Symposium
on Lattice Field Theory (Lattice 2014), 23-28 June 2014, Columbia University,
New York, NY, US
Low-energy Scattering of System and the Resonance-like Structure
In this paper, low-energy scattering of the meson
system is studied within L\"uscher's finite-size formalism using
twisted mass gauge field configurations. With three different pion mass values,
the -wave threshold scattering parameters, namely the scattering length
and the effective range , are extracted in channel. Our
results indicate that, in this particular channel, the interaction between the
two vector charmed mesons is weakly repulsive in nature hence do not support
the possibility of a shallow bound state for the two mesons, at least for the
pion mass values being studied. This study provides some useful information on
the nature of the newly discovered resonance-like structure
observed in various experiments.Comment: 11 pages, 6 figures. arXiv admin note: substantial text overlap with
arXiv:1403.131
Non-perturbative renormalization of overlap quark bilinears on domain wall fermion configurations
We present renormalization constants of overlap quark bilinear operators on
2+1-flavor domain wall fermion configurations. Both overlap and domain wall
fermions have chiral symmetry on the lattice. The scale independent
renormalization constant for the local axial vector current is computed using a
Ward Identity. The renormalization constants for the scalar, pseudoscalar and
vector current are calculated in the RI-MOM scheme. Results in the MS-bar
scheme are obtained by using perturbative conversion ratios. The analysis uses
in total six ensembles with lattice sizes 24^3x64 and 32^3x64.Comment: 7 pages, 10 figures, presented at the 31st International Symposium on
Lattice Field Theory (LATTICE 2013), 29 July - 3 August 2013, Mainz, German
Two Photon Decays of from Lattice QCD
We present an exploratory lattice study for the two-photon decay of
using twisted mass lattice QCD gauge configurations generated by the
European Twisted Mass Collaboration. Two different lattice spacings of
fm and fm are used in the study, both of which are of
physical size of 2. The decay widths are found to be KeV for the
coarser lattice and KeV for the finer lattice respectively where the
errors are purely statistical. A naive extrapolation towards the continuum
limit yields KeV which is smaller than the previous
quenched result and most of the current experimental results. Possible reasons
are discussed.Comment: 13 pages, 7 figures; matches the published versio
Non-perturbative renormalization of overlap quark bilinears on 2+1-flavor domain wall fermion configurations
We present renormalization constants of overlap quark bilinear operators on
2+1-flavor domain wall fermion configurations. This setup is being used by the
chiQCD collaboration in calculations of physical quantities such as strangeness
in the nucleon and the strange and charm quark masses. The scale independent
renormalization constant for the axial vector current is computed using the
Ward Identity. The renormalization constants for scalar, pseudoscalar and
vector current are calculated in the RI-MOM scheme. Results in the MS-bar
scheme are also given. The step scaling function of quark masses in the RI-MOM
scheme is computed as well. The analysis uses, in total, six different
ensembles of three sea quarks each on two lattices with sizes 24^3x64 and
32^3x64 at spacings a=(1.73 GeV)^{-1} and (2.28 GeV)^{-1}, respectively.Comment: 26 pages, 17 figures. More discussions on O(4) breaking effects, and
on the perturbative running and a^2p^2 extrapolation of Zs. A subsection for
the calculation of the step scaling function of quark mass is added.
References added. Version to appear in PR
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