TY - JOUR

T1 - QCD at finite baryon density

T2 - Nucleon droplets and color superconductivity

AU - Alford, Mark

AU - Rajagopal, Krishna

AU - Wilczek, Frank

N1 - Funding Information:
The research of MA and FW is supported in part by DOE grant DE-FG02-90ER40542; that of KR is supported in part by DOE cooperative research agreement DE-FC02-94ER40818.

PY - 1998/3/12

Y1 - 1998/3/12

N2 - We use a variational procedure to study finite density QCD in an approximation in which the interaction between quarks is modelled by that induced by instantons. We find that uniform states with conventional chiral symmetry breaking have negative pressure with respect to empty space at all but the lowest densities, and are therefore unstable. This is a precisely defined phenomenon which motivates the basic picture of hadrons assumed in the MIT bag model, with nucleons as droplets of chiral symmetry restored phase. At all densities high enough that the chirally symmetric phase fills space, we find that color symmetry is broken by the formation of a 〈qq〉 condensate of quark Cooper pairs. A plausible ordering scheme leads to a substantial gap in a Lorentz scalar channel involving quarks of two colors, and a much smaller gap in an axial vector channel involving quarks of the third color.

AB - We use a variational procedure to study finite density QCD in an approximation in which the interaction between quarks is modelled by that induced by instantons. We find that uniform states with conventional chiral symmetry breaking have negative pressure with respect to empty space at all but the lowest densities, and are therefore unstable. This is a precisely defined phenomenon which motivates the basic picture of hadrons assumed in the MIT bag model, with nucleons as droplets of chiral symmetry restored phase. At all densities high enough that the chirally symmetric phase fills space, we find that color symmetry is broken by the formation of a 〈qq〉 condensate of quark Cooper pairs. A plausible ordering scheme leads to a substantial gap in a Lorentz scalar channel involving quarks of two colors, and a much smaller gap in an axial vector channel involving quarks of the third color.

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U2 - 10.1016/S0370-2693(98)00051-3

DO - 10.1016/S0370-2693(98)00051-3

M3 - Article

AN - SCOPUS:0040633467

SN - 0370-2693

VL - 422

SP - 247

EP - 256

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

IS - 1-4

ER -