期刊：
EUROPEAN PHYSICAL JOURNAL A,2018年54(6):1-6 ISSN：1434-6001
通讯作者：
Hou, De-Fu
作者机构：
[Zhang, Le; Hou, De-Fu; Li, Jian] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;[Zhang, Le; Hou, De-Fu; Li, Jian] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.;[Zhang, Le] Wuhan Inst Technol, Coll Post & Telecommun, Wuhan 430070, Hubei, Peoples R China.
通讯机构：
[Hou, De-Fu] C;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.
摘要：
Using AdS/CFT, we investigate the influence of chemical potential on the holographic Schwinger effect at finite temperature. We study the potential barrier for the pair production and calculate the critical electric field
$ E_c$
by Dirac-Born-Infeld (DBI) action. It is found that the chemical potential decreases the potential barrier thus enhancing the Schwinger effect.
作者机构：
[Hou, De-fu] Cent China Normal Univ, Inst Particle Phys IOPP, Wuhan 430079, Hubei, Peoples R China.;[Hou, De-fu] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.;[Lin, Shu] Sun Yat Sen Univ, Sch Phys & Astron, Zhuhai 519082, Peoples R China.
通讯机构：
[Hou, De-fu] C;[Lin, Shu] S;Cent China Normal Univ, Inst Particle Phys IOPP, Wuhan 430079, Hubei, Peoples R China.;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.;Sun Yat Sen Univ, Sch Phys & Astron, Zhuhai 519082, Peoples R China.
摘要：
In quantum chromodynamics, axial charge is known to be nonconserved due to chiral anomaly and nonvanishing quark mass. In this paper, we explore the role of quark mass in axial charge fluctuation and dissipation. We present two separate calculations of the axial charge correlator, which describe dynamics of axial charge. The first is free quarks at a finite temperature. We find that axial charge can be generated through effective quantum fluctuations in free theory. However, the fluctuation does not follow a random walk behavior. Because of the presence of an axial symmetry breaking mass term, the axial charge also does not settle asymptotically to the thermodynamic limit given by susceptibility. The second calculation is in a weakly coupled quark gluon plasma. We find in the hard thermal loop (HTL) approximation, the quark-gluon interaction leads to random walk growth of the axial charge, but dissipation is not visible. We estimate the relaxation timescale for the axial charge, finding it lies beyond the HTL regime.
摘要：
We calculate the shear viscosity (η) and bulk viscosity (ζ) to entropy density (s) ratios η/s and ζ/s of a gluon plasma system in kinetic theory, including both the elastic gg↔gg forward scattering and the inelastic soft gluon bremsstrahlung gg ↔ ggg processes. Due to the suppressed contribution to η and ζ in the gg ↔ gg forward scattering and the effective g↔gg gluon splitting, Arnold, Moore and Yaffe (AMY) and Arnold, Dogan and Moore (ADM) have got the leading order computations for η and ζ in high-temperature QCD matter. In this paper, we calculate the correction to η and ζ in the soft gluon bremsstrahlung gg ↔ ggg process with an analytic method. We find that the contribution of the collision term from the gg ↔ ggg soft gluon bremsstrahlung process is just a small perturbation to the gg↔gg scattering process and that the correction is at ~5% level. Then, we obtain the bulk viscosity of the gluon plasma for the number-changing process. Furthermore, our leading-order result for bulk viscosity is the formula ζ∝α_s~2T~3/lnα_s~(-1) in high-temperature gluon plasma.
作者机构：
[Zhang, Zi-qiang; Luo, Zhong-jie] China Univ Geosci, Sch Math & Phys, Wuhan 430074, Hubei, Peoples R China.;[Hou, De-fu] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.
通讯机构：
[Zhang, Zi-qiang; Hou, De-fu] C;China Univ Geosci, Sch Math & Phys, Wuhan 430074, Hubei, Peoples R China.;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.
关键词：
AdS/CFT;QGP;Drag force;Diffusion coefficient
摘要：
We study the drag force and diffusion coefficient with respect to a moving heavy quark in a D-instanton background, which corresponds to the Yang-Mills theory in the deconfining, high-temperature phase. It is shown that the presence of the D-instanton density tends to increase the drag force and decrease the diffusion coefficient, reverse to the effects of the velocity and the temperature. Moreover, the inclusion of the D-instanton density makes the medium less viscous. (C) 2018 Elsevier B.V. All rights reserved.
作者机构：
[Zhang, Le; Qin, Guang-You; Hou, De-Fu] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;[Zhang, Le; Qin, Guang-You; Hou, De-Fu] Cent China Normal Univ, MOE, Key Lab Quark & Lepton Phys, Wuhan 430079, Hubei, Peoples R China.;[Zhang, Le] Wuhan Inst Technol, Coll Post & Telecommun, Wuhan 430070, Hubei, Peoples R China.
通讯机构：
[Qin, Guang-You] C;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;Cent China Normal Univ, MOE, Key Lab Quark & Lepton Phys, Wuhan 430079, Hubei, Peoples R China.
摘要：
We study the medium-induced gluon emission from a hard quark jet traversing the dense nuclear matter within the framework of deep inelastic scattering off a large nucleus. We extend the previous work and compute the single gluon emission spectrum including both transverse and longitudinal momentum exchanges between the hard jet parton and the medium constituents. On the other hand, with only transverse scattering and using static scattering centers for the traversed medium, our induced gluon emission spectrum in the soft gluon limit reduces to the Gyulassy-Levai-Vitev one-rescattering-one-emission formula.
关键词：
BGK collisional kernel;Collision rate;Dielectric function;Fluctuation energy loss;Quark–gluon plasma
摘要：
The polarization and fluctuation chromoelectromagnetic fields will be produced at the same time when a heavy quark travels through the quark-gluon plasma (QGP). These fields exerting in return on the heavy quark will cause energy loss to it. Collisions are one of the main sources of dissipation and are responsible for driving a system to approach equilibrium. We address the collision effects on the fluctuation energy exchange of the heavy quark in the medium. For this purpose, we apply the dielectric functions derived from the kinetic theory associated with the BGK collisional kernel which determine the fluctuation energy exchange. In that approach, the collision rate depicting the collision effects is embedded in the dielectric functions. Numerical results' show that compared to the collisionless case, the collision rate remarkably augments the fluctuation energy gain. (C) 2018 Elsevier B.V. All rights reserved.
作者机构：
[Hou, Defu; Chen, Jun; Hou, Wenjie; Qiu, Taotao] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.;[Chen, Jun; Hou, Wenjie; Qiu, Taotao] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;[Hou, Defu; Chen, Jun; Hou, Wenjie] Cent China Normal Univ, Inst Astrophys, Wuhan 430079, Hubei, Peoples R China.
通讯机构：
[Chen, Jun] C;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;Cent China Normal Univ, Inst Astrophys, Wuhan 430079, Hubei, Peoples R China.
关键词：
inflation;power spectrum;gravitaional waves
摘要：
In our previous work [1], a new kind of inflation model was proposed, which has the interesting property that its perturbation equation of motion gets a correction of k, due to the non-linearity of the kinetic term. Nonetheless, the scale-invariance of the power spectrum remains valid, both in large-k and small-k limits. In this paper, we investigate in detail the spectral index, the index running and the tensor/scalar ratio in this model, especially in the potential-driven case, and compare the results with the current PLANCK/BICEP observational data. We also discuss the tensor spectrum in this case, which is expected to be tested by future observations of primordial gravitational waves.
作者机构：
[Zhang, Zi-qiang] China Univ Geosci, Sch Math & Phys, Wuhan 430074, Hubei, Peoples R China.;[Hou, De-fu] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.
通讯机构：
[Zhang, Zi-qiang] C;China Univ Geosci, Sch Math & Phys, Wuhan 430074, Hubei, Peoples R China.
摘要：
We study the effect of a constant magnetic field on the imaginary part of a quarkonia potential in a strongly-coupled N = 4 SYM plasma. We consider the pair axis to be aligned perpendicularly and parallel to the magnetic field, respectively. For both cases, we find that the presence of the magnetic field tends to enhance the imaginary potential thus decreasing thethermal width. In addition, the magnetic field has a stronger effect on the imaginary potential when the pair axis is perpendicular to the magnetic field rather than parallel. (C) 2018 The Author(s). Published by Elsevier B.V.
作者机构：
[Hou, Defu; Zhang, Hui; Qin, Bin] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;[Hou, Defu; Zhang, Hui; Qin, Bin] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.;[Huang, Mei] Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China.;[Li, Danning] Jinan Univ, Dept Phys, Guangzhou 510632, Guangdong, Peoples R China.;[Li, Danning] Jinan Univ, Siyuan Labotorary, Guangzhou 510632, Guangdong, Peoples R China.
通讯机构：
[Qin, Bin] C;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.
摘要：
We study the nematic isotropic phase transition by applying the functional renormalization group to the Landau–de Gennes model. We derive the flow equations for the effective potential as well as the “couplings” constants and the anomalous dimension. We then solve the coupled flow equations on a grid using the Newton-Raphson method. A first-order phase transition is observed. We also investigate the nematic isotropic puzzle (the NI puzzle) in this paper. We obtain the NI transition temperature difference Tc−T*=5.85K.
作者机构：
[Zhang, Zi-qiang; Chen, Gang] China Univ Geosci Wuhan, Sch Math & Phys, Wuhan 430074, Peoples R China.;[Hou, De-fu] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Hou, De-fu] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOS, Wuhan 430079, Peoples R China.
通讯机构：
[Zhang, Zi-qiang] C;China Univ Geosci Wuhan, Sch Math & Phys, Wuhan 430074, Peoples R China.
摘要：
Imaginary potential and entropic force represent different mechanisms for melting the heavy quarkonium. In this paper, we study the chemical potential effect on these two quantities with respect to a moving quarkonium from the AdS/CTF duality. We observe that for both mechanisms the chemical potential has the same effect: the presence of the chemical potential tends to decrease the dissociation length. (C) 2017 The Author(s). Published by Elsevier B.V.
摘要：
The dissociation temperature of different quarkonium states has been examined with the anti de Sitter space/conformal field theory implied potential model. In order to determine the specific temperature, we explore the binding energy, average radius as well as the radial spectrum function with different bound states. It is shown that the internal energy between the constituent quarks is stronger than the free energy, and our melting temperatures are systematically lower than Lattice prediction. (C) 2016 Elsevier B.V. All rights reserved.
作者机构：
[Hou, Defu] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Hubei, Peoples R China.
通讯机构：
[Hou, Defu] C;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Hubei, Peoples R China.
摘要：
We study the phase diagram of two-flavor massless QCD at finite baryon density by applying the functional renormalization group (FRG) for a quark-meson model with σ, π, and ω mesons. The dynamical fluctuations of quarks, σ, and π are included in the flow equations, while the amplitudes of ω fields are also allowed to fluctuate. At high temperature the effects of the ω field on the phase boundary are qualitatively similar to the mean-field calculations; the phase boundary is shifted to the higher chemical potential region. As the temperature is lowered, however, the transition line bends back to the lower chemical potential region, irrespective of the strength of the vector coupling. In our FRG calculations, the driving force of the low temperature first order line is the fluctuations rather than the quark density, and the effects of ω fields have little impact. At low temperature, the effective potential at small σ field is very sensitive to the infrared cutoff scale, and this significantly affects our determination of the phase boundaries. The critical chemical potential at the tricritical point is affected by the ω-field effects, but its critical temperature stays around the similar value. Some caveats are given in interpreting our model results.
期刊：
International Journal of Modern Physics D,2017年26(4):1750027 ISSN：0218-2718
通讯作者：
Yin, Lei
作者机构：
[Hou, Defu; Yin, Lei] Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;[Hou, Defu; Yin, Lei] Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.;[Yin, Lei] Acad Sinica, Inst Phys, Taipei 11529, Taiwan.
通讯机构：
[Yin, Lei] C;Cent China Normal Univ, Inst Particle Phys, Wuhan 430079, Peoples R China.;Cent China Normal Univ, Key Lab Quark & Lepton Phys MOE, Wuhan 430079, Peoples R China.
摘要：
In this paper, we analytically study the consistency between the Ginzburg–Landau theory of the holographic superconductor in different ensembles and the fundamental thermodynamic relation, we derive the equation of motion of the scalar field which depicts the superconducting phase in canonical ensemble (CE) and a consistent formula to connect the holographic order-parameter to the Ginzburg–Landau coefficients in different thermodynamic ensembles, and we also study the spatially nonuniform Helmholtz free energy.
