Exploring a possible origin of the QCD critical endpoint

We develop a new model of the QCD critical endpoint by matching the deconfinement phase transition line of quark-gluon bags with the similar line at which the bag surface tension coefficient vanishes. Unlike all previous studies of such models the deconfined phase in our approach is defined not by an essential singularity of the isobaric partition function but its simple pole. As an unexpected result we find out that the first-order phase transition which is usually defined by a discontinuity of the first derivative of the bag system pressure results from a discontinuity of the derivative of surface tension coefficient of quark-gluon bags.     

Physical mechanism of the (tri)critical point generation

We discuss some ideas resulting from a phenomenological relation recently declared between the tension of string connecting the static quark-antiquark pair and surface tension of corresponding cylindrical bag. This relation analysis leads to the temperature of vanishing surface tension coefficient of the QGP bags at zero baryonic charge density as T _?? = 152.9 ± 4.5 MeV. We develop the view point that this temperature value is not a fortuitous coincidence with the temperature of (partial) chiral symmetry restoration as seen in the lattice QCD simulations. Besides, we argue that T _?? defines the QCD (tri)critical endpoint temperature and claim that a negative value of surface tension coefficient recently discovered is not a sole result but is quite familiar for ordinary liquids at the supercritical temperatures.     

Finite-size scaling as a tool for the search of the critical endpoint of QCD in heavy-ion data

We briefly discuss the role played by the finiteness of the system created in high-energy heavyion collisions (HIC’s) in the experimental search of the QCD critical endpoint and, in particular, the applicability of the predicting power of finite-size scaling plots in data analysis of current HIC’s.     

No-go theorem for critical phenomena in large-N(c) QCD

We derive some rigorous results on the chiral phase transition in QCD and QCD-like theories with a large number of colors, N(c), based on the QCD inequalities and the large-N(c) orbifold equivalence. We show that critical phenomena and associated soft modes are forbidden in flavor-symmetric QCD at finite temperature T and finite but not so large quark chemical potential μ for any nonzero quark mass. In particular, the critical point in QCD at a finite baryon chemical potential μ(B)=N(c)μ is ruled out, if the coordinate (T, μ) is outside the pion condensed phase in the corresponding phase diagram of QCD at a finite isospin chemical potential μ(I)=2μ.     

A simple and efficient route for the synthesis of di and tri(bis(indolyl) methanes) as new triarylmethanes

Preparation of di and tri(bis(indolyl) methanes) from di and trialdehydes and indoles in the presence of silica sulfuric acid was described. Reactions proceeded in good to excellent yields in acetonitrile as solvent at room temperature.     

Analytic continuation in two-color QCD: new results on the critical line

We test the method of analytic continuation from imaginary to real chemical potential in two-color QCD, which is free from the sign problem. In particular, we consider the analytic continuation of the critical line to real values of the chemical potential.     

QCD sum rule for Λ(1405)

Motivated by the recently constructed interpolation field for S₁₁(1535), we propose a new interpolating field for Λ(1405). Using this current, we calculate the mass of Λ(1405) based on the conventional QCD sum rule analysis. By calculating the Wilson coefficients up to dimension 8 operators and taking into account the mass corrections from s-quark, we find the calculated mass of Λ(1405) to be very close to its experimental value.     

面向全体学生的物理(续)——2006年美国全国物理教师协会"密立根奖"受奖演讲

当我写到现代物理时，经常在“现代”上加引号．从这个世纪初开始，这就是个对物理学来说令人困惑的称呼．也许它现在仍然有用，但20世纪和21世纪的物理学被一线的物理学家简单地称为“物理”，而不是“现代物理”．     

Searching for the QCD critical point in AA collisions at CERN SPS

We investigate the transverse momentum correlations of pairs of opposite charged pions near their production threshold. Through intermittency analysis, we search for power-law dependence on observation scale, as dictated by critical QCD. We analyze the data on the most central collisions in four A systems (A = p, C, Si, Pb) at maximum SPS energy. We find a significant effect for the SiSi system approaching in size the critical QCD predictions as measured by the intermittency index ? ₂. Absence of this effect in the (?? ^?, ?? ^?) sector of the SiSi system gives further support that the observed behavior in the isoscalar mode is of critical origin.     

Chinese Physics C(Formerly High Energy Physics and Nuclear Physics)

<正>Monthly,founded in 1977Published monthly in hard copy by Science Press and online by the Institute of High Energy Physics of the Chinese Academy of Sciences(domestic)and by IOP Publishing,Temple Circus,Temple Way,Bristol BS1 6HG,UK(international).     

Improved QCD vacuum for gauge groups SU(3) and SU(4)

The effective energy for a covariantly constant background field in a pure Yang-Mills theory is calculated to loop order one. For gauge group SU(3) [SU(4)] it is found that the “vacuum” configuration consists of two [three] constant color magnetic fields of equal non-zero magnitude orthogonal to each other in color as well as physical space. We conclude that the structure of the Copenhagen vacuum is more complex than previously expected.     

Study for the pentaquark potential in SU(3) lattice QCD

We perform the first study of the static pentaquark (5Q) potential V(5Q) in SU(3) quenched lattice QCD with 16(3) x 32 and beta = 6.0. From the 5Q Wilson loop, V(5Q) is calculated in a gauge-invariant manner, with the smearing method to enhance the ground-state component. V(5Q) is well described by the OGE-plus-multi-Y ansatz: a sum of the one-gluon-exchange (OGE) Coulomb term and the multi-Y-type linear term proportional to the minimal total length of the flux tube linking the five quarks. Comparing with QQ and3Q potentials, we find a universality of the string tension, sigma(QQ) approximately sigma(3Q) approximately sigma(5Q), and the OGE result for Coulomb coefficients.