arXiv subjects

Johannes Heinrich Weber

Publications and source records attributed to Johannes Heinrich Weber.

41 records · Page 3Linked to original sources

arXiv2016

QCD with Flavored Minimally Doubled Fermions

I discuss minimally doubled fermions fermions as an ultra-local formulation on the lattice for sea quarks that realize a non-singlet chiral symmetry. I introduce a non-singlet mass term for Karsten-Wilczek fermions and identify the appropriate representation of the SU(2) flavor group at finite lattice spacing. I present an algebraic proof that the symmetry of the quark determinant under charge conjugation and reflections of the Euclidean axes is preserved for Karsten-Wilczek fermions as sea quarks. Finally, I discuss how the flavor components in meson correlation functions with Karsten-Wilczek fermions emerge naturally and I show how taste-breaking can be avoided without fine tuning.

hep-lat↗

arXiv2016

Single quark entropy and the Polyakov loop

We study Quantum Chromodynamics (QCD) with 2+1 flavors with almost physical quark masses using the highly improved staggered quark action (HISQ). We calculate the Polyakov loop in a wide temperature range, obtain the free energy and the entropy of a single static quark and discuss the QCD crossover region in detail. We show that the entropy has a peak close to the chiral crossover and consider the consequences for the deconfinement aspects of the crossover phenomena. We study the renormalized Polyakov loop susceptibilities and place them into the context of the crossover. We also obtain a quantitative result for the onset of weak coupling behavior at high temperatures.

hep-lat↗

arXiv2016

Polyakov loop correlators and cyclic Wilson loop from lattice QCD

We discuss color screening in 2+1 flavor QCD in terms of free energies of a static quark-antiquark pair. Thermal modifications of long distance correlations in quark-antiquark systems are studied in terms of static meson correlators. We calculate the Polyakov loop correlator, the color-singlet Wilson line correlator in Coulomb gauge and the cyclic Wilson loop on lattices using the HISQ/Tree action and almost physical quark mases with $N_τ= 4, 6, 8, 10, 12$. We present results in the continuum limit for temperatures up to $T \lesssim 650$ MeV and discuss the linear divergence of the cyclic Wilson loop.

hep-lat↗

arXiv2016

Correlation functions with Karsten-Wilczek fermions

The Karsten-Wilczek action describes two chiral fermions but breaks the symmetries under both charge conjugation ($ \widehat{C}) $ and time reflection ($ \widehatΘ $) explicitly, though invariance under $ \widehat{CΘ} $ and a mirror fermion symmetry $ \widehat{TΘ} $ are maintained. These proceedings outline how the action's symmetries and the presence of the second fermion emerge in mesonic correlation functions. The residual symmetries explain the non-observation of broken time-reflection symmetry in a class of mesonic correlation functions. Time-reflection symmetry is enforced for correlation functions that are manifestly invariant under $ \widehat{C} $ or $ \widehat{T} $. Due to contributions from the second fermion, oscillating contributions arise in some mesonic correlation functions. A second condition for non-perturbative tuning of the relevant counterterm is obtained from these oscillations. Both non-perturbative tuning conditions are independent and agree within errors. Due to contributions from the second fermion, additional pseudoscalar states are observed in non-standard channels. Mass splittings between these additional states and the Goldstone boson vanish as $ \mathcal{O}(a^2) $.

hep-lat↗

arXiv2013

Numerical studies of Minimally Doubled Fermions

We have performed the first numerical study of minimally doubled fermions of the Karsten-Wilczek class in the quenched approximation. This requires fixing the counterterms, which arise due to hypercubic symmetry breaking induced by the Karsten-Wilczek term. Non-perturbative renormalisation criteria are formulated after a detailed study of the parameter dependence of mesonic observables. Minimisation of the mass anisotropy of the pseudoscalar ground state fixes non-perturbative renormalisation conditions for the counterterm coefficients. These anisotropies are mapped out by probing different euclidean components of the transfer matrix through calculations of the pseudoscalar ground state mass in different directions. The chiral behaviour of the pseudoscalar ground state is studied with the tuned Karsten-Wilczek action for multiple lattice spacings. Light pseudoscalar masses ($ M_{PS} \lesssim 250\,MeV $) were achieved in the quenched approximation without encountering exceptional configurations. The presence of quenched chiral logarithms is studied under the tentative assumption of Goldstone Boson-like behaviour.

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