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Title: Diquarks in the color-flavor locked phase of dense quark matter

Abstract

Diquark excitations of dense quark matter are considered in the framework of the Nambu-Jona-Lasinio model with three types of massless quarks in the presence of a quark number chemical potential {mu}. We investigate the effective action of meson and diquark fields at sufficiently high values of {mu}, where the color-flavor locked (CFL) phase is realized, and prove the existence of NG bosons in the sector of pseudoscalar diquarks. In the sector of scalar diquarks an additional NG boson is found, corresponding to the spontaneous breaking of the U(1){sub B} baryon symmetry in the CFL phase. Finally, the existence of massive scalar and pseudoscalar diquark excitations is demonstrated.

Authors:
 [1];  [2];  [3]
  1. Institut fuer Physik, Humboldt-Universitaet zu Berlin, 12489 Berlin (Germany)
  2. Institute for High Energy Physics, 142281, Protvino, Moscow Region (Russian Federation)
  3. (Protvino branch), 142281, Protvino, Moscow Region (Russian Federation)
Publication Date:
OSTI Identifier:
21011098
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevD.75.045005; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACTION INTEGRAL; BARYONS; COLOR MODEL; EXCITATION; FLAVOR MODEL; MESONS; POTENTIALS; QUARK MATTER; QUARKS; SCALARS; SYMMETRY; SYMMETRY BREAKING; U-1 GROUPS

Citation Formats

Ebert, D., Klimenko, K. G., and Dubna University. Diquarks in the color-flavor locked phase of dense quark matter. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.045005.
Ebert, D., Klimenko, K. G., & Dubna University. Diquarks in the color-flavor locked phase of dense quark matter. United States. doi:10.1103/PHYSREVD.75.045005.
Ebert, D., Klimenko, K. G., and Dubna University. Thu . "Diquarks in the color-flavor locked phase of dense quark matter". United States. doi:10.1103/PHYSREVD.75.045005.
@article{osti_21011098,
title = {Diquarks in the color-flavor locked phase of dense quark matter},
author = {Ebert, D. and Klimenko, K. G. and Dubna University},
abstractNote = {Diquark excitations of dense quark matter are considered in the framework of the Nambu-Jona-Lasinio model with three types of massless quarks in the presence of a quark number chemical potential {mu}. We investigate the effective action of meson and diquark fields at sufficiently high values of {mu}, where the color-flavor locked (CFL) phase is realized, and prove the existence of NG bosons in the sector of pseudoscalar diquarks. In the sector of scalar diquarks an additional NG boson is found, corresponding to the spontaneous breaking of the U(1){sub B} baryon symmetry in the CFL phase. Finally, the existence of massive scalar and pseudoscalar diquark excitations is demonstrated.},
doi = {10.1103/PHYSREVD.75.045005},
journal = {Physical Review. D, Particles Fields},
number = 4,
volume = 75,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • The spectrum of meson and diquark excitations of dense cold quark matter is investigated within the framework of a Nambu-Jona-Lasinio-type model for light quarks of two flavors. It was found that a first-order phase transition occurs when the chemical potential {mu} exceeds the critical value {mu}{sub c}=350 MeV. Above {mu}{sub c}, the diquark condensate <qq> forms, breaking the color symmetry of strong interaction. The masses of {pi} and {sigma} mesons are shown to grow with the chemical potential {mu} in the color-superconducting phase, but the mesons themselves become almost stable particles. Moreover, we have found in this phase an abnormalmore » number of three, instead of five, Nambu-Goldstone bosons, together with a color doublet of light stable diquark modes and a color-singlet heavy diquark resonance with mass {approx}1100 MeV. In the color-symmetric phase, i.e., for {mu}<{mu}{sub c}, a mass splitting of diquarks and antidiquarks is shown to arise if {mu}{ne}0, contrary to the case of a vanishing chemical potential, in which the masses of antidiquarks and diquarks are degenerate at the value {approx}700 MeV.« less
  • The Bethe-Salpeter equations for diquarks with the quantum numbers of the Nambu-Goldstone bosons are analyzed in the color-flavor locked phase of cold dense QCD with three quark flavors. The decay constants and the velocities of the Nambu-Goldstone bosons are calculated in the Pagels-Stokar approximation. It is also shown that, in contrast with the case of dense QCD with two flavors, there are no massive radial excitations with quantum numbers of the Nambu-Goldstone bosons in the color-flavor locked phase. The role of the Meissner effect in the pairing dynamics of diquarks is explained.
  • The spectrum of meson and diquark excitations of dense color neutral cold quark matter is investigated in the framework of a two-flavored Nambu-Jona-Lasinio-type model, including a quark {mu}- and color {mu}{sub 8}-chemical potential. It was found that, in the color superconducting (2SC) phase, i.e. at {mu}>{mu}{sub c}=342 MeV, {mu}{sub 8} acquires rather small values {approx}10 MeV in order to ensure the color neutrality. In this phase the {pi} and {sigma} meson masses are evaluated around {approx}330 MeV. The spectrum of scalar diquarks in the color neutral 2SC phase consists of a heavy [SU{sub c}(2)-singlet] resonance with mass {approx}1100 MeV, fourmore » light diquarks with mass 3|{mu}{sub 8}|, and one Nambu-Goldstone boson, which is in accordance with the Goldstone theorem. Moreover, in the 2SC phase there are five light stable particles as well as a heavy resonance in the spectrum of pseudoscalar diquarks. In the color symmetric phase, i.e. for {mu}<{mu}{sub c}, a mass splitting of scalar diquarks and antidiquarks is shown to arise if {mu}{ne}0, contrary to the case of {mu}=0, where the masses of scalar antidiquarks and diquarks are degenerate at the value {approx}700 MeV. If the coupling strength in the pseudoscalar diquark channel is the same as in the scalar diquark one (as for QCD-inspired Nambu-Jona-Lasinio models), then in the color symmetric phase pseudoscalar diquarks are not allowed to exist as stable particles.« less
  • The color neutral two-flavor superconducting phase of cold and dense quark matter is studied in the presence of constant magnetic fields and at moderate baryon densities. In the first part of the paper, a two-flavor effective Nambu-Jona-Lasinio model consisting of a chiral symmetry breaking ({chi}SB) mass gap {sigma}{sub B}, a color superconducting (CSC) mass gap {Delta}{sub B} and a color chemical potential {mu}{sub 8} is introduced in the presence of a rotated U(1) magnetic field B-tilde. To study the phenomenon of magnetic catalysis in the presence of strong magnetic fields, the gap equations corresponding to {sigma}{sub B} and {Delta}{sub B},more » as well as {mu}{sub 8} are solved in the lowest Landau level approximation. In the second part of the paper, a detailed numerical analysis is performed to explore the effect of any arbitrary magnetic field on the above mass gaps and the color chemical potential. The structure of the {chi}SB and CSC phases is also presented in the {mu}{sub c}-e-tildeB plane, and the effect of {mu}{sub 8} on the phase structure of the model is explored. As it turns out, whereas the transition from the {chi}SB to CSC phase is of first order, nonvanishing {mu}{sub 8} affects essentially the second order phase transition from CSC to the normal phase.« less
  • We calculate the correlation functions needed to describe the linear response of superfluid matter, and go on to calculate the differential cross section for neutral-current neutrino scattering in superfluid neutron matter and in color-flavor-locked quark matter. We report the first calculation of scattering rates that includes neutrino interactions with both pair-breaking excitations and low-lying collective excitations (Goldstone modes). Our results apply both above and below the critical temperature, allowing use in simulations of neutrino transport in supernovae and neutron stars.