共查询到20条相似文献,搜索用时 31 毫秒
1.
We investigate possible mass shift and width broadening of J/psi in hot gluonic matter using QCD sum rules. Input values of gluon condensates at finite temperature are extracted from lattice QCD data for the energy density and pressure. Although stability of the moment ratio is achieved only up to T/Tc approximately 1.05, the gluon condensates cause a decrease of the moment ratio, which results in a change of the spectral properties. Using the Breit-Wigner form for the phenomenological side, we find that the mass shift of J/psi just above Tc can reach maximally 200 MeV and the width can broaden to dozens of MeV. 相似文献
2.
P. Kolář 《Czechoslovak Journal of Physics》1989,39(11):1317-1320
Conclusions The sets (3) and (4) of condensates have been compared using the QCD sum rules (2) with indefinite weight functions. A bad matching between both sets of condensates and experimental data has been obtained. The standard values (3) appear to be closer to data but some increase ofQ is necessary to improve the agreement. Only higher values ofm
0
2
could change the results of this analysis. It is interesting that negative values ofm
0
2
considerably improve the agreement with data; note that this quantity cannot be determined with a sufficient accuracy. We conclude that the QCD sum rules (2) cannot definitely determine a privileged set of condensates.Dedicated to Academician Václav Votruba on the occasion of his eightieth birthday. 相似文献
3.
We present the dispersion relations for quasiparticle excitations about the color-flavor locked ground state of QCD at high baryon density. In the presence of condensates which pair light and strange quarks there need not be an energy gap in the quasiparticle spectrum. This raises the possibility of gapless color superconductivity, with a Meissner effect but no minimum excitation energy. Analysis within a toy model suggests that gapless color superconductivity may occur only as a metastable phase. 相似文献
4.
Zhi-Gang Wang 《International Journal of Theoretical Physics》2012,51(2):507-517
In this article, we take the scalar diquarks as point particles and describe them as basic quantum fields, then introduce
the SU(3) color gauge interaction and new vacuum condensates to study the nonet scalar mesons as tetraquark states with the QCD
sum rules. Comparing with the conventional quark currents, the diquark currents have the outstanding advantage to satisfy
the two criteria of the QCD sum rules more easily. 相似文献
5.
ZHOU Li-Juan MENG Cheng-Ju PAN Ji-Huan LIU Bao-Rong MA Wei-Xing 《理论物理通讯》2008,49(3):717-722
Based on the parameterized fully dressed quark propagator proposed by us, the tensor susceptibilities of QCD vacuum and quark vacuum condensates are investigated. Our predicted values of the tensor susceptibilities are in agreement with those predicted by many other theoretical models with QCD feature. The results also show that the tensor susceptibility of QCD vacuum strongly depends on flavor of quark but not sensitive to variation of quark vacuum condensates. However, the quark vacuum condensate is very sensitive to the change of cut-off-parameter μ^2 of the integration, that is, it depends on the separation point of perturbative and non-perturbative QCD region. The successful predictions clearly indicate the extensive validity of our parameterized fully dressed quark propagator used here. 相似文献
6.
I. Caprini 《Czechoslovak Journal of Physics》1991,41(1):12-19
A new method for the determination of the QCD condensates from low-energy hadronic data is proposed. It generalizes the usual QCD finite-energy sum rules, taking into account explicitely the truncation error of the high-energy QCD expansion. The method is applied to the e+e– annihilation intoI= 1 hadrons, indicating a rather large domain for the values of the gluon and four quark condensates. 相似文献
7.
S. Narison 《Physics letters. [Part B]》1984,142(3):168-172
Using a spectral function sum rules approach, we derive some constraints among the Goldstone parameters, the lowest dimension vacuum condensates and the mass of the chiral matter superfield in supersymmetric QCD (SQCD). These relations are consistent with previous results on SQCD and complement them. 相似文献
8.
We analyze the behaviour that correlation functions ought to have on the lattice in order to reproduce QCD sum rules in the continuum limit. We formulate a set of relations between lattice correlation functions of meson operators at small time separation and the quark condensates responsible for spontaneous breakdown of chiral symmetery. We suggest that the degree to which such relations are satisfied will provide a set of consistency checks on the ability of lattice Monte Carlo simulations to reproduce the correct spontaneous chiral symmetry breaking of the continuum theory. 相似文献
9.
We study the interplay between chiral and diquark condensates within the framework of the Ginzburg-Landau free energy, and classify possible phase structures of two and three-flavor massless QCD. The QCD axial anomaly acts as an external field applied to the chiral condensate in a color superconductor and leads to a crossover between the broken chiral symmetry and the color superconducting phase, and, in particular, to a new critical point in the QCD phase diagram. 相似文献
10.
11.
We study the properties of QCD vacuum state in this paper. The values of various local quark vacuum condensates, quark-gluon mixed vacuum condensates, and the structure of non-local quark vacuum condensate are predicted by the solution of Dyson-Schwinger Equations in "rainbow" approximation with three sets of different parameters for effective gluon propagator. The light quark virtuality is also obtained in a consistent way. Our all theoretical results here are in good agreement with the empirical values used widely in literature and many other theoretical calculations. 相似文献
12.
13.
Qi-Nan Wang Zhu-Feng Zhang T. G. Steele Hong-Ying Jin Zhuo-Ran Huang 《中国物理C(英文版)》2017,41(7):074107-074107
We improve the Monte-Carlo based QCD sum rules by introducing the rigorous H¨older-inequalitydetermined sum rule window and a Breit-Wigner type parametrization for the phenomenological spectral function.In this improved sum rule analysis methodology, the sum rule analysis window can be determined without any assumptions on OPE convergence or the QCD continuum. Therefore, an unbiased prediction can be obtained for the phenomenological parameters(the hadronic mass and width etc.). We test the new approach in the ρ meson channel with re-examination and inclusion of α_s corrections to dimension-4 condensates in the OPE. We obtain results highly consistent with experimental values. We also discuss the possible extension of this method to some other channels. 相似文献
14.
The two-gluon and three-gluon condensates at finite temperature are calculated in the framework of the grand partition function for a weak-interacting instanton medium of a disordered phase. The interference parts of both chromomagnetic and chromoelectric two-gluon condensates are found to be small but still significant for a quantitative determination of the value of the condensates at very low temperature, and negligible at the temperature above 1.5ΛMS, with respect to their non-interference ones. The interference parts of the threegluon condensates are found to be quite small even at very low temperature. With the QCD scale parameter fixed by the value of the Lorentz invariant two-gluon condensate at zero temperature, the value of the three-gluon condensate at zero temperature is found to be coincident with the phenomenological estimate. The values of the gluon condensates decrease when temperature increases, and are negligible when the temperature goes beyond 2.5ΛMS in the case of the SUC(3) pure gauge theory. 相似文献
15.
The values of the gluon and four-quark vacuum condensates are estimated using recent experimental data on the semileptonic τ-lepton decays τ→vτ+nπ, which determine the vector and axialvector hadronic spectral functions. An optimal estimate is achieved through a systematic combined use Finite Energy, Laplace and Gaussian transform QCD sum rules. As a byproduct, the values of the dimensiond=8 vacuum condensates in the vector and axial-vector channels are also estimated. 相似文献
16.
We discuss QCD sum rule constraints based on moments of vector meson spectral distributions in the vacuum and in a nuclear
medium. Sum rules for the two lowest moments of these spectral distributions do not suffer from uncertainties related to QCD
condensates of dimension higher than four. We exemplify these relations for the case of the ω meson and discuss the issue
of in-medium mass shifts from this viewpoint.
Received: 22 December 1998 / Revised version: 13 January 1999 相似文献
17.
A.A. Almasy K. Schilcher H. Spiesberger 《The European Physical Journal C - Particles and Fields》2008,55(2):237-248
We have used the latest data from the ALEPH Collaboration to extract values for QCD condensates up to dimension d=12 in the
V-A channel and up to dimension d=8 in the V, A and V+A channels. Performing two- and three-parameter fits, we obtain new
results for the correlations of condensates. The results are consistent and agree with most of the previous results found
in the literature. 相似文献
18.
We study vacuum of QCD in this work. The structure of non-local
quark vacuum condensate, values of various local quark and gluon
vacuum condensates, quark-gluon mixed vacuum condensate, quark and
gluon virtuality in QCD vacuum state, quark dynamical mass and
susceptibility of QCD vacuum state to external field are predicted by use of the solutions of Dyson-Schwinger equations in “rainbow”
approximation with a modeling gluon propagator and three different
sets of quark-quark interaction parameters. Our theoretical
predictions are in good agreement with the correspondent empirical
values used widely in literature, and many other theoretical
calculations. The quark propagator and self-energy functions are
also obtained from the numerical solutions of Dyson-Schwinger
equations. This work is centrally important for studying
non-perturbative QCD, and has many important applications both in
particle and nuclear physics. 相似文献
19.
D. Vretenar 《The European physical journal. Special topics》2008,156(1):37-67
A microscopic framework of nuclear energy density functionals
is reviewed, which establishes a direct relation between low-energy QCD and
nuclear structure, synthesizing effective field theory
methods and principles of density functional theory.
Guided by two closely related features of QCD in the
low-energy limit: a) in-medium changes of vacuum condensates, and
b) spontaneous breaking of chiral symmetry; a relativistic energy
density functional is developed and applied in studies of ground-state
properties of spherical and deformed nuclei. 相似文献
20.
Frédéric Jugeau 《中国物理C(英文版)》2010,34(9)
We investigate the AdS/QCD duality for the two-point correlation functions of the lowest dimension scalar meson and scalar glueball operators,in the case of the Soft Wall holographic model of QCD.Masses and decay constants as well as gluon condensates are compared to their QCD estimates.In particular,the role of the boundary conditions for the bulk-to-boundary propagators is emphasized. 相似文献