We present a first look at the spectroscopy of SU(4) gauge theory coupled to two flavors of Dirac fermions in the two-index antisymmetric representation, which is a real representation. We compute meson and diquark masses, the pseudoscalar and vector meson decay constants, and the masses of six-quark baryons. We make comparisons with large- expectations.
DOI:https://doi.org/10.1103/PhysRevD.91.114502
© 2015 American Physical Society
Phase diagram of the SU(4) AS2 theory in the plane. The solid lines are drawn to guide the eye and are not a fit to the data. From right to left: , , , and . The dotted line indicates weakening of the bulk transition to a crossover.
Reuse & PermissionsLeft: Quark mass as a function of in different volumes at . Right: Average plaquette as a function of in different volumes at .
Reuse & PermissionsLeft: Scatter plots of the Polyakov loop in the two different phases on lattices at . Right: Average Polyakov loop on lattices for different and values. The jump of the average Polyakov loop values for each value signals a finite-temperature transition.
Reuse & PermissionsSommer parameters and from the dynamical SU(3) and SU(4) data sets [panels (a) and (b), respectively].
Reuse & PermissionsMeson spectroscopy. On the left, the squared pseudoscalar mass scaled by ; on the right, times the vector meson mass. The abscissa is times the AWI quark mass. The data sets are black squares for quenched SU(3) fundamentals, black diamonds for quenched SU(5) fundamentals, black octagons for quenched SU(7) fundamentals, and red crosses for SU(4) AS2; the fancy diamonds are the PQ data. Finally, the blue squares are SU(3) with two dynamical, fundamental flavors.
Reuse & PermissionsTwo ways to match bare parameters: panel (a) vs and panel (b) vs . The data sets are black squares for quenched SU(3) fundamentals, black diamonds for quenched SU(5) fundamentals, black octagons for quenched SU(7) fundamentals, and red crosses for SU(4) AS2. Finally, the blue squares are SU(3) with two dynamical, fundamental flavors.
Reuse & PermissionsVariation of vs for roughly matched data using . The diamonds are for , octagons for , and squares for . The blue symbols are the dynamical SU(3) data, and the red symbols are the SU(4) AS2 data. Black symbols show quenched fundamental results.
Reuse & PermissionsDifferent determinations of in the SU(4) AS2 theory: (1) from with all four mass values, (2) from with the lowest three mass values, (3) from with all four mass values, and (4) from with the lowest three mass values.
Reuse & PermissionsPseudoscalar decay constant. The abscissa is times the AWI quark mass. The data sets are black squares for quenched SU(3) fundamentals, black diamonds for quenched SU(5) fundamentals, black octagons for quenched SU(7) fundamentals, and red crosses for SU(4) AS2; the fancy diamonds are the PQ data. Finally, the blue squares are SU(3) with two dynamical, fundamental flavors.
Reuse & PermissionsVector meson decay constant. The abscissa is times the AWI quark mass. The data sets are labeled as in Fig. 9.
Reuse & PermissionsBaryons. The black data are from the top quenched SU(7), SU(5), and SU(3) data. The blue octagons are SU(3) with dynamical fermions. The red points are the six-quark baryons in SU(4) AS2, octagons are for dynamical data sets, and fancy diamonds are for partially quenched ones.
Reuse & PermissionsFit to rotor formula (7.1) at . Octagons (with error bars) are the data points; squares are the best fit values.
Reuse & PermissionsThe parameter [panel (a)] and [panel (b)] from two-flavor degenerate mass data as a function of from a fit to Eq. (7.1). Data from the quenched SU(3), SU(5), and SU(7) multiplets are shown, respectively, as squares, diamonds, and octagons. Red crosses and fancy diamonds show the SU(4) data, unquenched and partially quenched, and the blue squares are the dynamical SU(3) data sets.
Reuse & Permissionsvs from the rotor formula (7.1); black diamonds from quenched SU(3), blue squares from full SU(3). The SU(4) data are shown as red octagons for the dynamical sets and fancy diamonds for the partially quenched set.
Reuse & PermissionsFor comparison, vs from the rotor formula (7.1) from the quenched fundamental data sets of Ref. [43]: , 5, and 7 data sets are squares, diamonds, and octagons.
Reuse & PermissionsThe quantity defined in Eq. (7.2), plotted vs the ratio . Data shown include quenched fundamental SU(3), SU(5), and SU(7) (black squares, diamonds, and octagons), dynamical SU(3) (blue squares), and dynamical SU(4) AS2 (red crosses). We also plot in purple results from Ref. [46] for quenched fundamental SU(4), for bare gauge coupling (fancy diamonds), and (fancy crosses).
Reuse & Permissions
