6,815 research outputs found
Large N_c Expansion in Chiral Quark Model of Mesons
We study SU(3)_L\timesSU(3)_R chiral quark model of mesons up to the next
to leading order of expansion. Composite vector and axial-vector mesons
resonances are introduced via non-linear realization of chiral SU(3) and vector
meson dominant. Effects of one-loop graphs of pseudoscalar, vector and
axial-vector mesons is calculated systematically and the significant results
are obtained. We also investigate correction of quark-gluon coupling and
relationship between chiral quark model and QCD sum rules. Up to powers four of
derivatives, chiral effective lagrangian of mesons is derived and evaluated to
the next to leading order of . Low energy limit of the model is
examined. Ten low energy coupling constants in ChPT are
obtained and agree with ChPT well.Comment: 49 pages, latex file, 6 eps figure
Noncommutative QED and Muon Anomalous Magnetic Moment
The muon anomalous value, , is calculated up to one-loop
level in noncommutative QED. We argue that relativistic muon in E821 experiment
nearly always stays at the lowest Landau level. So that spatial coordinates of
muon do not commute each other. Using parameters of E821 experiment, KG
and muon energy 3.09GeV/c, we obtain the noncommutativity correction to
is about , which significantly makes standard model
prediction close to experiment.Comment: revtex, 6 page, 5 figure
Rigorous Effective Field Theory Study on Pion Form Factor
We study cross section and phase shift of
scattering below 1GeV in framework of chiral constituent quark model.
The results including all order contribution of the chiral perturbation
expansion and all one-loop effects of pseudoscalar mesons, but without any
adjust parameters. Width of predicted by the model strongly depends on
transition momentum-square . We show that the mass pamameter of
-meson in its propagator is very different from its physical mass due to
momentum-dependent width of . The mass difference between and
are predicted successfully. The rigorous theoretical prediction on
cross section and the phase shift in
scattering agree with data excellentlly.Comment: revtex file, 10 pages, 4 eps figure
Chiral Expansion Theory at Vector Meson Scale
We study physics on and in framework of chiral
constituent quark model. The effective action is derived by proper vertex
method, which can capture all order information of chiral expansion. The
expansion is also studied systematically. It is shown that the
momentum expansion at vector meson energy scale converges slowly, and the loop
effects of pseudoscalar meson play an important role at this energy scale. We
provide a method to prove the unitarity of S-matrix in any low-energy effective
theory of QCD. Phenomenologically, we study decays for ,
, , and
, mixing and their mass splitting, pion
form factor, phase shift and light quark masses at vector meson energy
scale. These results include all order contribution of vector meson momentum
expansion and is up to next to leading order of expansion. All of
these theoretical predictions agree with data very well. The unitarity of
S-matrix yielded by this framework is examined. The Breit-Winger formula for
resonance propagator is derived.Comment: revtex file, 36 pages, 10 eps figure
Probing Light Stop Pairs at the LHC
In this work, we study the light stop pair signals at the LHC. We explore the
SUSY parameter space with non-universal gaugino and third generation masses at
the GUT scale. Recent LHC SUSY search results based on 35pb and
1fb of data are implemented to put the limits on stop pair events. The
dark matter relic density and direct detection constraints are also taken into
account. Detailed simulations on the signals and background for some benchmark
points are performed, and it is found that the stop pair signals usually escape
the LHC search if the present cut conditions are used. We also explore the
potential and sensitivity of ILC to probe such scenarios. It is found that the
ILC can detect them with an integrated luminosity of a few tens of fb.Comment: 35pages, 13figure
The Scale on Chiral Symmetry Breaking
We study the relation between the scale of chiral symmetry spontaneously
breaking and constituent quark mass. We argue that this relation partly reveals
strong interaction origination of chiral symmetry breaking. We show that the
relation can be obtained via checking unitarity region of low-energy effective
field theory of QCD. This effective field theory must manifestly include
consistent quark mass as parameter. Thus we derive this effective field theory
from naive chiral constituent quark model. The phenomenological value obtained
by this method agree with usual one determined by pion decay constant.Comment: 6 pages, 1 figure
Human migration patterns in large scale spatial with the resume data
Researches on the human mobility have made great progress in many aspects,
but the long-term and long-distance migration behavior is lack of in-depth and
extensive research because of the difficult in accessing to household data. In
this paper, we use the resume data to discover the human migration behavior on
the large scale scope. It is found that the asymmetry in the flow structure
which reflects the influence of population competition is caused by the
difference of attractiveness among cities. This flow structure can be
approximately described by the gravity model of spatial economics. Besides, the
value of scaling exponent of distance function in the gravity model is less
than the value of short-term travel behavior. It means that, compared with the
short-term travel behavior, the long-term human migration behavior is less
sensitive. Moreover, the scaling coefficients of each variable in the gravity
model are investigated. The result shows that the economic level is a mainly
factor on the migration
Light stop/sbottom pair production searches in the NMSSM
In this work, we study the constraints on the scenario of light stops and
sbottoms in the next-to-minimal supersymmetric standard model (NMSSM),
especially by a 125 GeV Higgs boson discovery and the LHC bounds on
supersymmetry. The constraints from dark matter detections are also taken into
account. From the parameter scan, we find that the NMSSM can well accommodate a
light Higgs boson around 125 GeV and decay patterns. We would like to stress
that the LHC direct supersymmetry searches with b-tagging are very powerful and
can set strong bounds on many NMSSM parameter points with light stops and
sbottoms. We find is a very promising channel
for light stop detection if the mass splitting between and
is very small. It is also pointed out that in order to close
the parameter space of light stops and sbottoms, new search strategies for
signal channels such as and may be necessary.Comment: 43 pages, 18 fig
Resummation Study on Decay in Chiral Theory of Mesons
We improve calculation in chiral theory of
mesons by resummation calculation for vector mesons physics and restudy decay
. A complete and compact expression for
(up to ) is obtained, from which an important non-perturbative
conclusion is given based on convergence and unitarity consideration.Comment: 5 pages, 2 figure
Relativistic corrections to the form factors of into -wave Charmonium
We investigate the form factors of meson into -wave charmonium
within the nonrelativistic QCD effective theory and obtain the next-to-leading
order relativistic corrections to the form factors, where both the meson
and the charmonium are treated as the nonrelativistic bound states. Treating
the charm quark as a light quark in the limit \ , some form
factors are identical at the maximum recoil point, which are consistent with
the predictions in the heavy-quark effective theory and the large-energy
effective theory. Considering that the branching ratios of and have been measured by the LHCb and ATLAS
Collaborations recently, we employ the form factors of meson into
-wave charmonium at the next-to-leading order accuracy to these two decay
channels and obtain more precise predictions of their decay rates. Numerical
results indicate that the factorizable diagrams dominate the contribution in
these two channels, while the colour-suppressed and the annihilation diagrams
contribute less than 10 percent. Our results are consistent with the LHCb and
ATLAS data.Comment: 10 pages, 2 figures and 2 tables. The typos are corrected and more
discussions are adde
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