### Abstract

We study chemical-potential dependence of confinement and mass gap in QCD with adjoint fermions in spacetime with one spatial compact direction. By calculating the one-loop effective potential for the Wilson line in the presence of a chemical potential, we show that a center-symmetric phase and a center-broken phase alternate when the chemical potential in units of the compactification scale is increased. In the center-symmetric phase we use semiclassical methods to show that photons in the magnetic bion plasma acquire a mass gap that grows with the chemical potential as a result of anisotropic interactions between monopole-instantons. For the neutral fermionic sector which remains gapless perturbatively, there are two possibilities at a nonperturbative level: either to remain gapless (unbroken global symmetry) or to undergo a novel superfluid transition through a four-fermion interaction (broken global symmetry). If the latter is the case, this leads to an energy gap of quarks proportional to a new nonperturbative scale L-1exp[-1/(g4μL)], where L denotes the circumference of S1, the low-energy physics is described by a Nambu-Goldstone mode associated with the baryon number, and there exists a new type of BEC-BCS crossover of the diquark pairing as a function of the compactification scale at a small chemical potential.

Original language | English |
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Article number | 034022 |

Journal | Physical Review D |

Volume | 96 |

Issue number | 3 |

DOIs | |

Publication status | Published - 2017 Aug 1 |

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### ASJC Scopus subject areas

- Physics and Astronomy (miscellaneous)

### Cite this

*Physical Review D*,

*96*(3), [034022]. https://doi.org/10.1103/PhysRevD.96.034022

**Phases of circle-compactified QCD with adjoint fermions at finite density.** / Kanazawa, Takuya; Ünsal, Mithat; Yamamoto, Naoki.

Research output: Contribution to journal › Article

*Physical Review D*, vol. 96, no. 3, 034022. https://doi.org/10.1103/PhysRevD.96.034022

}

TY - JOUR

T1 - Phases of circle-compactified QCD with adjoint fermions at finite density

AU - Kanazawa, Takuya

AU - Ünsal, Mithat

AU - Yamamoto, Naoki

PY - 2017/8/1

Y1 - 2017/8/1

N2 - We study chemical-potential dependence of confinement and mass gap in QCD with adjoint fermions in spacetime with one spatial compact direction. By calculating the one-loop effective potential for the Wilson line in the presence of a chemical potential, we show that a center-symmetric phase and a center-broken phase alternate when the chemical potential in units of the compactification scale is increased. In the center-symmetric phase we use semiclassical methods to show that photons in the magnetic bion plasma acquire a mass gap that grows with the chemical potential as a result of anisotropic interactions between monopole-instantons. For the neutral fermionic sector which remains gapless perturbatively, there are two possibilities at a nonperturbative level: either to remain gapless (unbroken global symmetry) or to undergo a novel superfluid transition through a four-fermion interaction (broken global symmetry). If the latter is the case, this leads to an energy gap of quarks proportional to a new nonperturbative scale L-1exp[-1/(g4μL)], where L denotes the circumference of S1, the low-energy physics is described by a Nambu-Goldstone mode associated with the baryon number, and there exists a new type of BEC-BCS crossover of the diquark pairing as a function of the compactification scale at a small chemical potential.

AB - We study chemical-potential dependence of confinement and mass gap in QCD with adjoint fermions in spacetime with one spatial compact direction. By calculating the one-loop effective potential for the Wilson line in the presence of a chemical potential, we show that a center-symmetric phase and a center-broken phase alternate when the chemical potential in units of the compactification scale is increased. In the center-symmetric phase we use semiclassical methods to show that photons in the magnetic bion plasma acquire a mass gap that grows with the chemical potential as a result of anisotropic interactions between monopole-instantons. For the neutral fermionic sector which remains gapless perturbatively, there are two possibilities at a nonperturbative level: either to remain gapless (unbroken global symmetry) or to undergo a novel superfluid transition through a four-fermion interaction (broken global symmetry). If the latter is the case, this leads to an energy gap of quarks proportional to a new nonperturbative scale L-1exp[-1/(g4μL)], where L denotes the circumference of S1, the low-energy physics is described by a Nambu-Goldstone mode associated with the baryon number, and there exists a new type of BEC-BCS crossover of the diquark pairing as a function of the compactification scale at a small chemical potential.

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U2 - 10.1103/PhysRevD.96.034022

DO - 10.1103/PhysRevD.96.034022

M3 - Article

VL - 96

JO - Physical Review D

JF - Physical Review D

SN - 2470-0010

IS - 3

M1 - 034022

ER -