3194304
Kaon Condensation and Enforced Charge Neutrality of the Color-Flavor Locked Phase
We investigate the influence of charged kaon condensation in hadronic sector on the formation of the electron-free charge neutral quark matter of equipartition of three light flavors, i.e., a phenomenon called ``enforced electrical neutrality" of the color-flavor locked (CFL) phase. We employ the chiral quark model which is assumed to be applicable, "bottom-up," toward chiral restoration while accessible to kaon condensation in the hadronic sector. Approaching "bottom-up" the high density regime is more appropriate in addressing the properties of compact stars than approaching "top-down" from asymptotic QCD. It turns out that the presence of hadronic kaon condensation makes the electron-free charge-neutral CFL phase energetically more favorable with a relatively small color-superconducting gap $\Delta_0\sim 20$ MeV compared to $\Delta_0\sim 70$ MeV required in the absence of such kaon condensation.
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.
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.
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.
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}
118268883
Feynman's Branes and Feynman's Oscillators
Based on Feynman’s lifetime efforts on quantum mechanics and relativity, it is concluded that the basic difference between field theory and string theory is that field theory is based on running waves while string theory should deal with standing waves in the Lorentz-covariant regime. At the 1970 spring meeting of the American Physical Society held in Washington, DC, R. P. Feynman stunned the audience by proposing harmonic oscillators for relativistic bound states, instead of Feynman diagrams. His talk was later published in the paper of Feynman, Kislinger, and Ravndal [Phys. Rev. D, Vol. 3, 2706 (1971)]. These authors noted that the hadron mass spectra can be predicted by the degeneracy of the three-dimensional harmonic oscillators. In so doing, they started with the Lorentz-invariant differential equation for the harmonic oscillator, and obtained Lorentz invariant solutions. However, their solutions are not normalizable in the time-separation variable and cannot carry probability interpretation. It is pointed out that there are solutions normalizable in the time-separation variable within the framework � � ,
119339738
Photon spin as a rotation in gauge space
It is shown that the photon spin is associated with the rotational invariance in a two-dimensional space spanned by the two ''translation'' parameters of the E(2)-like little group of the Poincare group. Since the translation in the E(2)-like space is a gauge transformation, the photon spin can be associated with an orbitlike rotation with nonzero radius in the gauge space.
120517451
Lorentz Squeezed Hadrons and Hadronic Temperature
Abstract It is shown possible to define the temperature of Lorentz-squeezed hadrons in terms of their speed. Within the framework of the covariant harmonic oscillator formalism which is the simplest scientific language for Lorentz-squeezed hadrons, the hadronic temperature is measured through ( v c ) 2 = exp ( - h ω kT ) . As the temperature rises, the hadron goes through a transition from the confinement phase to a plasma phase.
124314883
Radial excitations in the symmetric quark model
SummaryRadial excitation modes are analyzed for nonstrange baryons. It is found that the baryon radial mode exhibits a harmonicoscillatorlike mass spectrum with the energy spacing of 270 MeV. It is shown that a largeSU6 force is responsible for this narrow spacing. It is shown also that thisSU6 force is responsible for the exceptionally low mass of the Roper resonance.RiassuntoSi analizzano i modi di eccitazione radiali per barioni non strani. Si trova che il modo radiale del barione presenta un spettro di massa del tipo dell’oscillatore armonico con intervallo di energia di 270 MeV. Si dimostra che una grande forza diSU6 è responsabile di questo piccolo intervallo. Si dimostra anche che questa forza diSU6 è responsabile della massa eccezionalmente bassa della risonanza di Roper.РеэюмеПроводится аналиэ мод радиальных воэбуждений для нестранных барионов. Получается, что барионная радиальная мода обнаруживает массовый спектр, аналогичный спектру гармонического осциллятора, с интервалом 270 МзВ. Покаэывается, что больщаяSU6 сила является ответственной эа зтот уэкий интервал. Также отмечается, что зтаSU6 сила ответственна эа зкспоненциально инэкую массу реэонанса Ропера.
56300970
Representations of the Poincaré group for relativistic extended hadrons
Representations of the Poincare group are constructed from the relativistic harmonic oscillator wave functions which have been effective in describing the physics of internal quark motions in the relativistic quark model. These wave functions are solutions of the Lorentz‐invariant harmonic oscillator differential equation in the ’’cylindrical’’ coordinate system moving with the hadronic velocity in which the time‐separation variable is treated separately. This result enables us to assert that the hadronic mass spectrum is generated by the internal quark level excitation, and that the hadronic spin is due to the internal orbital angular momentum. An addendum relegated to PAPS contains discussions of detailed calculational aspects of the Lorentz transformation, and of solutions of the oscillator equation which are diagonal in the Casimir operators of the homogeneous Lorentz group. It is shown there that the representation of the homogeneous Lorentz group consists of solutions of the oscillator partial diffe...