119302026
The quark number susceptibility in the hard-thermal-loop approximation
With the help of the vector Ward–Takahashi identity we derive a general formula for the quark number susceptibility (QNS) which expresses the QNS as an integral expression only involving the full quark propagator at finite temperature and chemical potential. The QNS at finite temperature and zero chemical potential is calculated with the dressed quark propagator in the hard-thermal-loop (HTL) approximation. A comparison of our result with the results of the QNS in the HTL approximation in previous literatures is given.
124327174
The Renormalized Equation of State and Quark Star
By means of the EOS of QCD at zero temperature and finite quark chemical potential we proposed [Phys. Rev. D 78(2008)054001] in the framework of rainbow-ladder approximation of Dyson-Schwinger approach, we investigate the structure of quark star and its property. It is found that the mass-radius relation in our model is very different from that of usual quark star models, but similar to neutron star models. The obtained mass of quark star is about 1.75M⊙ ~ 2.2M⊙. The obtained radius of quark star is 22 ~ 26 km, which is obviously larger than the results in other models. The reason for this discrepancy is analyzed.
121809939
The Wigner solution of quark gap equation and chiral phase transition of QCD at finite temperature and nonzero chemical potential
By employing some modification to the normal NJL model, we discuss the Wigner solution of quark gap equation at finite temperature and chemical potential when the current quark mass m is nonzero. The discovery of the coexistence of the Nambu solution and the Wigner solution at finite temperature and chemical potential beyond the chiral limit is of great importance in the study of the chiral phase transition of QCD. Using the pressure difference between Nambu phase and Wigner phase (or in other words, the bag constant) as an order parameter for chiral phase transition, we draw a possible phase diagram based on our calculations.
121136055
The equation of state of QCD under hard-dense-loop approximation
Based on the method proposed by Zong et al., we calculate the equation of state (EOS) of QCD at zero temperature and finite quark chemical potential under the hard-dense-loop (HDL) approximation. A comparison between the EOS under HDL approximation and the cold, perturbative EOS of QCD proposed by Fraga, Pisarski and Schaffner-Bielich is made. It is found that when µ is less than 4.7 GeV, the pressure density calculated using HDL approximation is much larger than that calculated using perturbation theory. This enhancement of the obtained pressure density with respect to that of perturbation theory can be regarded as a possible explanation for the strong coupled QGP. It is also expected that the obtained EOS can be applied in the study of neutron stars.
120263943
Quark-meson vertices and pion properties at finite chemical potential
Based on the rainbow-ladder approximation of the Dyson-Schwinger equations and the assumption of the analyticity of the quark-meson vertex in the neighborhood of zero chemical potential ({mu}=0) and neglecting the {mu}-dependence of the dressed gluon propagator, we use the method of studying the dressed quark propagator at finite chemical potential given in [H. S. Zong, L. Chang, F.Y. Hou, W. M. Sun, and Y. X. Liu, Phys. Rev. C 71, 015205 (2005)] to show that the axial-vector quark-meson vertex at finite {mu} can be obtained from the corresponding one at {mu}=0 by a shift of variable: {gamma}{sub 5{nu}}{sup j}[{mu}](k, p)={gamma}{sub 5{nu}}{sup j}(k{approx}, p), where k and p are the relative and total momentum of the quark-antiquark pair, respectively, and k{approx}=(k-vector, k{sub 4}+i{mu}). Similar relations hold for any other type of quark-meson vertex. This feature would facilitate the numerical calculations of the quark-meson vertex function at finite {mu} considerably. Based on these results and using the dressed quark propagator at {mu}=0 proposed in [R. Alkofer, W. Detmold, C. S. Fischer, and P. Maris, Phys. Rev. D 70, 014014 (2004)], we calculate the pion decay constant f{sub {pi}} and the pion mass m{sub {pi}} at finite {mu} and a comparison of ourmore » results with those in the literature is made.« less
53688784
Locate QCD critical end point in a continuum model study
A bstractWith a modified chemical potential dependent effective model for the gluon propagator, we try to locate the critical end point (CEP) of strongly interacting matter in the framework of Dyson-Schwinger equations (DSE). Beyond the chiral limit, we find that Nambu solution and Wigner solution could coexist in some area. Using the CornwallJackiw-Tomboulis (CJT) effective action, we show that these two phases are connected by a first order phase transition. We then locate CEP as the end point of the first order phase transition line. Meanwhile, based on CJT effective action, we give a direct calculation for the chiral susceptibility and thereby study the crossover.
119925663
A general derivation of the Hall conductivity on the noncommutative plane
By algebraic approach, Hall conductivity on the noncommutative plane is derived exactly. The calculations are carried out in noncommutative phase spaces without any representations or perturbation expansions of the coordinate and momentum operators.
45741338
Diagnosing degenerate Higgs bosons at 125 GeV.
We develop diagnostic tools that would provide incontrovertible evidence for the presence of more than one Higgs boson near 125 GeV in the LHC data.
16931224
Loop induced W+- H-+ associated production via photon-photon collisions in the THDM and the MSSM
We study the loop induced production of charged Higgs boson associated with W-boson via photon-photon collisions at linear colliders (LC). The investigation is carried out under the two-Higgs-doublet model(THDM) and the minimal supersymmetric model (MSSM) using full on-mass-shell renormalization scheme. The numerical analysis of their production rates is presented with some typical parameter sets. The results show that the total cross sections in frame of the MSSM at linear colliders(LC) can reach 0.1 femto barn quantitatively. The contributions from supersymmetric sector can lead to an order of magnitude enhancement of the cross section in some parameter space. We conclude that the associated WH production rate in photon-photon collision mode is comparable to that in ee collision mode. PACS number(s): 12.60.Jv, 12.60.Fr, 12.15.Lk, 13.85.-t The project supported by National Natural Science Foundation of China
118460136
The Crepant Transformation Conjecture for Toric Complete Intersections
Abstract Let X and Y be K -equivalent toric Deligne–Mumford stacks related by a single toric wall-crossing. We prove the Crepant Transformation Conjecture in this case, fully-equivariantly and in genus zero. That is, we show that the equivariant quantum connections for X and Y become gauge-equivalent after analytic continuation in quantum parameters. Furthermore we identify the gauge transformation involved, which can be thought of as a linear symplectomorphism between the Givental spaces for X and Y , with a Fourier–Mukai transformation between the K -groups of X and Y , via an equivariant version of the Gamma-integral structure on quantum cohomology. We prove similar results for toric complete intersections. We impose only very weak geometric hypotheses on X and Y : they can be non-compact, for example, and need not be weak Fano or have Gorenstein coarse moduli space. Our main tools are the Mirror Theorems for toric Deligne–Mumford stacks and toric complete intersections, and the Mellin–Barnes method for analytic continuation of hypergeometric functions.
118135921
Two Higgs Bosons at the Tevatron and the LHC
The best fit to the Tevatron results in the bb channel and the mild excesses at CMS in the gamma-gamma channel at 136 GeV and in the tau-tau channel above 132 GeV can be explained by a second Higgs state in this mass range, in addition to the one at 125 GeV recently discovered at the LHC. We show that a scenario with two Higgs bosons at 125 GeV and 136 GeV can be consistent with practically all available signal rates, including a reduced rate in the tau-tau channel around 125 GeV as reported by CMS. An example in the parameter space of the general NMSSM is given where, moreover, the signal rates of the 125 GeV Higgs boson in the gamma-gamma channels are enhanced relative to the expectation for a SM Higgs boson of this mass.