Tue·Dec 4, 2007Tuesday·December 4, 2007

1. 01*

   Probing the chiral limit with clover fermions II: The baryon sector

   M. Göckeler🇩🇪 · Philipp Hägler🇩🇪 · R. Horsley🇬🇧 · Y. Nakamura🇩🇪 · M. Ohtani🇩🇪 · D. Pleiter🇩🇪 · P.E.L. Rakow🇬🇧 · A. Schäfer🇩🇪 · G. Schierholz🇩🇪 · W. Schroers🇩🇪 · H. Stüben🇩🇪 · J.M. Zanotti🇬🇧

   Algorithmic progress in recent years made it possible to simulate QCD with Nf=2 flavours of O(a)-improved Wilson fermions at very light quark masses. We present the current results for baryon spectrum states, the nucleon axial coupling and the lowest moment of unpolarised nucleon structure functions. Special emphasis is given to a comparison of our calculations with results from chiral effective theories.

   hep-latPoS(2007)·11 citations
2. 02*

   Bulk Viscosity of a Gas of Massless Pions

   Jiunn-Wei Chen🇹🇼 · Juven Wang🇹🇼

   In the hadronic phase, the dominant configuration of QCD with two flavors of massless quarks is a gas of massless pions. We calculate the bulk viscosity (zeta) using the Boltzmann equation with the kinetic theory generalized to incorporate the trace anomaly. We find that the dimensionless ratio zeta/s, s being the entropy density, is monotonic increasing below T=120 MeV, where chiral perturbation theory is applicable. This, combined with previous results, shows that zeta/s reaches its maximum near the phase transition temperature Tc, while eta/s, eta being the shear viscosity, reaches its minimum near Tc in QCD with massless quarks.

   ↳ hep-phhep-exhep-latnucl-ex+1PRC(2009)·63 citations
3. 03*

   Diquark effects in light baryon correlators from lattice QCD

   Thomas DeGrand🇺🇸 · Zhaofeng Liu🇫🇷 · Stefan Schaefer🇩🇪

   We study the role of diquarks in light baryons through point to point baryon correlators. We contrast results from quenched simulations with ones with two flavors of dynamical overlap fermions. The scalar, pseudoscalar and axial vector diquarks are combined with light quarks to form color singlets. The quenched simulation shows large zero mode effects in correlators containing the scalar and pseudoscalar diquark. The two scalar diquarks created by gamma_5 and gamma_0gamma_5 lead to different behavior in baryon correlators, showing that the interaction of diquarks with the third light quark matters: we do not see an isolated diquark. In our quark mass range, the scalar diquark created by gamma_5 seems to play a greater role than the others.

   ↳ hep-phhep-latPRD(2008)·39 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.