Two-color QCD at high density

Boz, Tamer; Giudice, Pietro; Hands, Simon; Skullerud, Jon-Ivar; Williams, Anthony G.

doi:10.1063/1.4938682

Cited by 14 publications

(16 citation statements)

References 13 publications

(18 reference statements)

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“…The phase diagram of the quark-meson-diquark model for QC 2 D from the functional renormalization group [32] is shown in Figure 1. The qualitative features resemble lattice results [16,17], especially when the Polyakov-loop variable is included in the effective model description [33]. Evidence of the BEC-BCS crossover inside the diquarkcondensation phase was also provided from lattice simulations [9] albeit still close to the bulk phase of SU (2) (see below).…”

Section: Introductionsupporting

confidence: 62%

“…Beside this technical aspect, QCD-like theories are interesting in their own right. On the lattice, QC 2 D has been studied with staggered [1,[4][5][6][7][8][9][10][11][12] and Wilson fermions [13][14][15][16][17][18]. In contrast to QCD, the color-singlet baryons are diquarks and hence bosonic in two-color QCD, for example, while fermionic baryons do not exist in its spectrum.…”

Section: Introductionmentioning

confidence: 99%

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Continuum Goldstone spectrum of two-color QCD at finite density with staggered quarks

et al. 2019

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We carry out lattice simulations of two-color QCD and spectroscopy at finite density with two flavors of rooted-staggered quarks and a diquark source term. As in a previous four-flavor study [1], for small values of the inverse gauge coupling we observe a Goldstone spectrum which reflects the symmetry-breaking pattern of a Gaussian symplectic chiral random-matrix ensemble (GSE) with Dyson index βD = 4, which corresponds to any-color QCD with adjoint quarks in the continuum instead of QC2D wih fundamental quarks. We show that this unphysical behavior occurs only inside of the bulk phase of SU (2) gauge theory, where the density of Z2 monopoles is high. Using an improved gauge action and a somewhat larger inverse coupling to suppress these monopoles, we demonstrate that the continuum Goldstone spectrum of two-color QCD, corresponding to a Gaussian orthogonal ensemble (GOE) with Dyson index βD = 1, is recovered also with rootedstaggered quarks once simulations are performed away from the bulk phase. We further demonstrate how this change of random-matrix ensemble is reflected in the distribution of eigenvalues of the Dirac operator. By computing the unfolded level spacings inside and outside of the bulk phase, we demonstrate that, starting with the low-lying eigenmodes which determine the infrared physics, the distribution of eigenmodes continuously changes from the GSE to the GOE one as monopoles are suppressed.

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Section: Introductionsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Continuum Goldstone spectrum of two-color QCD at finite density with staggered quarks

et al. 2019

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“…Instead it is proportional to the quark mass and decreases with increasing chemical potential. Let us note that dense QC 2 D in the hadronic phase and the BEC phase was intensively studied within lattice simulations in a series of papers [27,31,32,37,38,45] where reasonable agreement with ChPT was observed.…”

Section: Temperaturesmentioning

confidence: 99%

Lattice study of static quark-antiquark interactions in dense quark matter

Astrakhantsev

Bornyakov

Брагута

et al. 2019

J. High Energ. Phys.

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In this paper we study the interactions among a static quark-antiquark pair in the presence of dense two-color quark matter with lattice simulation. To this end we compute Polyakov line correlation functions and determine the renormalized color averaged, color singlet and color triplet grand potentials. The color singlet grand potential allows us to elucidate the number of quarks induced by a static quark antiquark source, as well as the internal energy of such a pair in dense quark matter. We furthermore determine the screening length, which in the confinement phase is synonymous with the string breaking distance. The screening length is a decreasing function of baryon density, due to the possibility to break the interquark string via a scalar diquark condensate at high density. We also study the large distance properties of the color singlet grand potential in a dense medium and find that it is well described by a simple Debye screening formula, parameterized by a Debye mass and an effective coupling constant. The latter is of order of unity, i.e. even at large density two-color quark matter is a strongly correlated system.

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“…In this work, we thus introduce the diquark source term in the action to solve the second problem following refs. [15][16][17][18][19][20][21][22][23][24] (see section 2) and attempt to find out the phase structure in the vanishing limit of the source term.…”

Section: Introductionmentioning

confidence: 99%

“…As for the phase structure of dense two-colour QCD with N f = 2, earlier lattice simulations [18][19][20][21][22][23][24] including the diquark source parameter j in the action provided low temperature data for the diquark condensate, the Polyakov loop, the quark number density and the chiral condensate as a function of quark chemical potential µ. By taking the limit of j → 0, a hadronic phase with vanishing diquark condensate was found to change into a superfluid phase with nonzero diquark condensate around µ ∼ m PS /2.…”

Section: Introductionmentioning

confidence: 99%

Two-colour QCD phases and the topology at low temperature and high density

Iida

Itou

Lee

2020

J. High Energ. Phys.

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We delineate equilibrium phase structure and topological charge distribution of dense two-colour QCD at low temperature by using a lattice simulation with two-flavour Wilson fermions that has a chemical potential µ and a diquark source j incorporated. We systematically measure the diquark condensate, the Polyakov loop, the quark number density and the chiral condensate with improved accuracy and j → 0 extrapolation over earlier publications; the known qualitative features of the low temperature phase diagram, which is composed of the hadronic, Bose-Einstein condensed (BEC) and BCS phases, are reproduced. In addition, we newly find that around the boundary between the hadronic and BEC phases, nonzero quark number density occurs even in the hadronic phase in contrast to the prediction of the chiral perturbation theory (ChPT), while the diquark condensate approaches zero in a manner that is consistent with the ChPT prediction. At the highest µ, which is of order the inverse of the lattice spacing, all the above observables change drastically, which implies a lattice artifact. Finally, at temperature of order 0.45T c , where T c is the chiral transition temperature at zero chemical potential, the topological susceptibility is calculated from a gradient-flow method and found to be almost constant for all the values of µ ranging from the hadronic to BCS phase. This is a contrast to the case of 0.89T c in which the topological susceptibility becomes small as the hadronic phase changes into the quark-gluon plasma phase.

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Two-color QCD at high density

Cited by 14 publications

References 13 publications

Continuum Goldstone spectrum of two-color QCD at finite density with staggered quarks

Continuum Goldstone spectrum of two-color QCD at finite density with staggered quarks

Lattice study of static quark-antiquark interactions in dense quark matter

Two-colour QCD phases and the topology at low temperature and high density

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