118543970
The equation of state and quark number susceptibility in the hard-dense-loop approximation
Based on the method proposed by H S Zong and W M Sun (2008 Phys. Rev. D 78 054001), we calculate the equation of state (EOS) of quantum chromodynamics (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 the pressure under the HDL approximation is generally smaller than the perturbative result. In addition, we also calculate the quark number susceptibility (QNS) at finite temperature and finite chemical potential under the hard-thermal/dense-loop (HTL/HDL) approximation and compare our results with the corresponding ones in the previous literature.
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.
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.
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.
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
109831879
Modified magnicon for high-gradient accelerator R&D
A design is presented of a modified 34.3 GHz magnicon amplifier with a TE311-mode output cavity, to replace the existing magnicon at Yale Beam Physics Lab Test Facility whose output cavity operates in the TM310 mode. The main goal for the new design is to achieve robust day-to-day reliable operation at pulsed power levels up to 25 MW.
119395913
Proof of principle for a high sensitivity search for the electric dipole moment of the electron using the metastable a(1)[^3\Sigma^+] state of PbO
The metastable a(1)[^3\Sigma^+] state of PbO has been suggested as a suitable system in which to search for the electric dipole moment (EDM) of the electron. We report here the development of experimental techniques allowing high-sensitivity measurements of Zeeman and Stark effects in this system, similar to those required for an EDM search. We observe Zeeman quantum beats in fluorescence from a vapor cell, with shot-noise limited extraction of the quantum beat frequencies, high counting rates, and long coherence times. We argue that improvement in sensitvity to the electron EDM by at least two orders of magnitude appears possible using these techniques.
4807800
Fixing the quantum three-point function
A bstractWe propose a new method for the computation of quantum three-point functions for operators in $ \mathfrak{s}\mathfrak{u} $(2) sectors of $ \mathcal{N} $ = 4 super Yang-Mills theory. The method is based on the existence of a unitary transformation relating inhomogeneous and long-range spin chains. This transformation can be traced back to a combination of boost operators and an inhomogeneous version of Baxter’s corner transfer matrix. We reproduce the existing results for the one-loop structure constants in a simplified form and indicate how to use the method at higher loop orders. Then we evaluate the one-loop structure constants in the quasiclassical limit and compare them with the recent strong coupling computation.
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
119738846
Two-beam detuned-cavity electron accelerator structure
Progress has been made in the theory, development, cavity design and optimization, beam dynamics study, beam transport design, and hardware construction for studies of a detuned two-beam electron accelerator structure.