Journal article

Publication year: 2019

Journal: Physical Review D

Volume number: 100

Issue number: 11

ISSN: 2470-0010

eISSN: 2470-0029

Open access status: Hybrid

DOI Link: https://doi.org/10.1103/PhysRevD.100.114507

Publisher: American Physical Society

Abstract: 
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 [J. B. Kogut, D. Toublan, and D. K. Sinclair, The PseudoGoldstone spectrum of two color QCD at finite density, Phys. Rev. D 68, 054507 (2003).], 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 beta(D) = 4, which corresponds to any-color QCD with adjoint quarks in the continuum instead of QC(2)D with fundamental quarks. We show that this unphysical behavior occurs only inside of the bulk phase of SU(2) gauge theory, where the density of Z(2) 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 beta(D) = 1, is recovered also with rooted-staggered 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.

Harvard Citation style: Wilhelm, J., Holicki, L., Smith, D., Wellegehausen, B. and von Smekal, L. (2019) Continuum Goldstone spectrum of two-color QCD at finite density with staggered quarks, Physical Review D, 100(11), Article 114507. https://doi.org/10.1103/PhysRevD.100.114507

APA Citation style: Wilhelm, J., Holicki, L., Smith, D., Wellegehausen, B., & von Smekal, L. (2019). Continuum Goldstone spectrum of two-color QCD at finite density with staggered quarks. Physical Review D. 100(11), Article 114507. https://doi.org/10.1103/PhysRevD.100.114507