Mixed action with Borici-Creutz fermions on a staggered sea

Abstract

Mixed action lattice QCD with Borici-Creutz valence quarks on staggered sea is investigated.The counter terms in Borici-Creutz action are fixed nonperturbatively to restore the broken parity and time symmetries. When symmetries are restored, the usual signatures of partial quenching are recovered. We find the scalar correlators to be negative for lower valence quark masses but the errorbars are rather large when their mean values are negative at earlier time slices. The size of unitarity violation due to different discretization of valence and sea quark is determined by measuring ∆ mix and is found to be comparable with other mixed action studies.

Spin-taste structure of minimally doubled fermions

“…However, the one-link operators in Eq. ( 17) do not permit a simultaneous eigenbasis with PT or C, and one-link site-splitting [18] does not access the tastes.…”

“…[7]. Attempts to tune with the wrong counterterm produced explicit Tsymmetry violation in pion correlators for any non-zero coefficient [18], while a correct counterterm respecting the symmetries as in Eq. ( 18) will not induce it despite mistuning.…”

“…While ad-hoc site-splitting prescriptions could approximately filter the two tastes, e.g. as suggested for KW fermions [17] or BC fermions [18], they cannot accommodate the two different non-trivial ST structures in each of the two variants, and cannot bring forth the exact ST representations of su(2) for these discretizations. In the interacting theory the taste symmetry is approximate, and the eigenvalues arrange into taste multiplets [19].…”