5924990
BARYON DENSITY AND THE DILATED CHIRAL QUARK MODEL
We calculate perturbatively the effect of density on hadronic properties using the chiral quark model implemented by the QCD trace anomaly to see the possibility of constructing a Lorentz-invariant Lagrangian at finite density. We calculate the density-dependent masses of the constituent quark, the scalar field, and the pion in one-loop order using the technique of thermofield dynamics. In the chiral limit, the pion remains massless at finite density. It is found that the tadpole-type corrections lead to decreasing masses with increasing baryon density, while the radiative corrections induce Lorentz-symmetry-breaking terms. We found in the large N{sub c} limit with large scalar mass that the tadpoles dominate and the mean-field approximation is reliable, giving rise to a Lorentz-invariant Lagrangian with masses decreasing as the baryon density increases. {copyright} {ital 1997} {ital The American Physical Society}
18064237
The effect of kaon condensation on quark-antiquark condensate in dense matter
Abstract Assuming that at sufficiently high densities the constituent quarks become relevant degrees of freedom, we study within the framework of a chiral quark model the influence of s -wave K − condensation on the quark–antiquark condensates. We find that, in linear density approximation, the presence of a K − condensate quenches the u ¯ u condensate, but that the d ¯ d condensate remains unaffected up to the chiral order under consideration. We discuss the implication of the suppressed u ¯ u condensate for flavor-dependent chiral symmetry restoration in dense matter.
14062402
Consequences of the partial restoration of chiral symmetry in AdS/QCD
Chiral symmetry is an essential concept in understanding QCD at low energy. We treat the chiral condensate, which measures the spontaneous breaking of chiral symmetry, as a free parameter to investigate the effect of partially restored chiral symmetry on the physical quantities in the frame work of an AdS/QCD model. We observe an interesting scaling behavior among the nucleon mass, pion decay constant and chiral condensate. We propose a phenomenological way to introduce the temperature dependence of a physical quantity in the AdS/QCD model with the thermal AdS metric.
119447142
Renormalization group analysis ofρ-meson properties at finite density
We calculate the density dependence of the $\rho$-meson mass and coupling constant($g_{\rho NN}$) for $\rho$-nucleon-nucleon vertex at one loop using the lagrangian where the $\rho$-meson is included as a dynamical gauge boson of a hidden local symmetry. From the condition that thermodynamic potential should not depend on the arbitrary energy scale, renormalization scale, one can construct a renormalization group equation for the thermodynamic potential and argue that the various renormalization group coefficients are functions of the density or temperature. We calculate the $\beta$-function for $\rho$-nucleon-nucleon coupling constant ($g_{\rho NN}$) and $\gamma$-function for $\rho$-meson mass ($\gamma_{m_\rho}$). We found that the $\rho$-meson mass and the coupling constant for $g_{\rho NN}$ drop as density increases in the low energy limit.
119099546
Quark number susceptibility with finite chemical potential in holographic QCD
We study the quark number susceptibility in holographic QCD with a finite chemical potential or under an external magnetic field at finite temperature. We first consider the quark number susceptibility with the chemical potential. We observe that approaching Tc from high temperature regime, χq/T2 develops a peak as we increase the chemical potential, which confirms recent lattice QCD results. We discuss this behavior in connection with the existence of the critical end point in the QCD phase diagram. We also consider the quark number susceptibility under the external magnetic field. We predict that the quark number susceptibility exhibits a blow-up behavior at low temperature as we raise the value of the magnetic field. We finally spell out some limitations of our study.
7806265
Meson exchange effect on color superconductivity
We investigate the effects of pion and gluon exchanges on the formation of two-flavor color superconductivity at moderate density, � < 1GeV . The chiral quark model proposed by Manohar and Georgi containing pions as well as gluons is employed to show that the pion exchange reduces substantially the value of the superconducting gap gotten with the gluon exchange only. It turns out that the pion exchanges produce a repulsion between quark-quark pair in a spin and isospin singlet state. We suggest that the phase consisiting of pions, gluons and quarks is one of the candidates of in-medium QCD phase at moderate density.
18430798
Measuring the top quark mass with m_T2 at the LHC
We investigate the possibility to measure the top quark mass using the collider variable $m_{T2}$ at the LHC experiment. Monte Carlo studies of $m_{T2}$ are performed with the events corresponding to the dilepton decays of $t\bar{t}$ produced at the LHC with 10 $fb^{-1}$ integrated luminosity. Our analysis suggests that the top quark mass can be determined by the $m_{T2}$ variable alone with a good precision at the level of 1 GeV.
121020837
Observation of zeros and amplification of quadrupole-matrix-element contributions to photoelectron angular distributions
56009963
Single bunch collective effects in PLS storage ring
The single bunch collective effects such as the bunch lengthening due to the potential well distortion and the microwave instability which also increases the energy spread, the transverse head-tail instability, and the transverse strong head-tail instability are investigated in the Pohang Light Source storage ring. The threshold current and the Chao-Gareyte scaling factor of the bunch lengthening, the longitudinal broadband impedance, and the transverse impedance have been measured and compared with the ZAP code results.
28166980
Lorentz Group in Ray Optics
It has been almost one hundred years since Einstein formulated his special theory of relativity in 1905. He showed that the basic space-time symmetry is dictated by the Lorentz group. It is shown that this group of Lorentz transformations is not only applicable to special relativity, but also constitutes the scientific language for optical sciences. It is noted that coherent and squeezed states of light are representations of the Lorentz group. The Lorentz group is also the basic underlying language for classical ray optics, including polarization optics, interferometers, the Poincare\'e sphere, one-lens optics, multi-lens optics, laser cavities, as well multilayer optics.
120208172
Little groups, the quark model and gauge transformations
Two modern applications of Wigner's original work on the Poincare group are discussed. The little group for a particle with non-zero mass is O(3), and that for a massless particle is isomorphic to E(2). First, we use the covariant harmonic-oscillator model to illustrate that the basic symmetry of the space-time separation between the quarks inside a hadron is isomorphic to that of O(3). Second, we give a realization of the E(2) group which described both the rotation and gauge transformation of the photon wave function.