Fri·Aug 27, 2004Friday·August 27, 2004

1. 01*

   Cold, dense matter via the lattice NJL model

   David N. Walters🇬🇧

   We simulate the lattice Nambu--Jona-Lasinio (NJL) model in 3+1-dimensions at non-zero baryon chemical potential (mu) and zero temperature (T) and treat the results as phenomenologically relevant for cold, dense quark matter. Measurements of the chiral condensate indicate a crossover in the thermodynamic limit, whilst at high chemical potential and zero temperature we observe a non-zero diquark condensate and a gap in the fermion dispersion relation, which together provide evidence for BCS superfluidity. In particular, the size of gap is found to be approximately 15% the value of the vacuum fermion mass and roughly independent of mu in the chirally restored phase.

   hep-lat0 citations
2. 02*

   Residual Confinement in High-Temperature Yang-Mills Theory

   Axel Maas🇩🇪 · Jochen Wambach🇩🇪 · Burghard Gruter🇩🇪 · Reinhard Alkofer🇩🇪

   The infrared behavior of Landau gauge gluon and ghost propagators are investigated in Yang-Mills theory at non-vanishing temperatures. Self-consistent solutions are presented for temperatures below the presumed phase transition and in the infinite temperature limit. Gluon confinement is manifest in the infrared behavior of these propagators. As expected confinement prevails below the phase transition. In the infinite-temperature limit a qualitative change is observed: the chromoelectric sector exhibits a near-perturbative behavior while long-range chromomagnetic interactions, mediated by soft ghost modes, are still present. The latter behavior is in agreement with corresponding lattice results. It furthermore implies that part of the gluons are still confined.

   ↳ hep-phhep-latnucl-th1 citation
3. 03*

   Semileptonic decays of $D$ mesons in three-flavor lattice QCD

   C. Aubin🇺🇸 · C. Bernard🇺🇸 · C. DeTar🇺🇸 · M. Di Pierro🇺🇸 · A. El-Khadra🇺🇸 · Steven Gottlieb🇺🇸 · E. B. Gregory🇺🇸 · U. M. Heller🇺🇸 · J. Hetrick🇺🇸 · A. S. Kronfeld🇺🇸 · P. B. Mackenzie🇺🇸 · D. Menscher🇺🇸 and 8 other authors

   We present the first three-flavor lattice QCD calculations for $D\to \pi l\nu$ and $D\to Kl\nu$ semileptonic decays. Simulations are carried out using ensembles of unquenched gauge fields generated by the MILC collaboration. With an improved staggered action for light quarks, we are able to simulate at light quark masses down to 1/8 of the strange mass. Consequently, the systematic error from the chiral extrapolation is much smaller than in previous calculations with Wilson-type light quarks. Our results for the form factors at $q^2=0$ are $f_{+}^{D\to \pi }(0)=0.64(3)(6)$ and $f_{+}^{D\to K}(0)=0.73(3)(7)$, where the first error is statistical and the second is systematic, added in quadrature. Combining our results with experimental branching ratios, we obtain the CKM matrix elements $|V_{cd}|=0.239(10)(24)(20)$ and $|V_{cs}|=0.969(39)(94)(24)$, where the last errors are from experimental uncertainties.

   ↳ hep-phhep-latPRL(2005)·274 citations
4. 04*

   Landau-gauge condensates from the quark propagator on the lattice

   Enrique Ruiz Arriola🇪🇸 · Patrick Oswald Bowman🇺🇸 · Wojciech Broniowski🇵🇱

   We compute the dimension-2 condensate, <A^2>, and the dimension-4 mixed condensate, <\bar q A q>, from the recent quenched lattice results for the quark propagator in the Landau gauge. We fit the lattice data to the Operator Product Expansion in the "fiducial" region 1.2 GeV < Q < 3 GeV. Our result for the dynamical gluon mass at the scale of 10 GeV^2 is m_A=600-650 MeV, in agreement with independent determinations. For the mixed Landau gauge condensate of dimension-4 we get alpha_s <\bar q g A q> = (-0.11 +/- 0.03) GeV^4. This value is an order of magnitude larger than the <G^2> gluon condensate.

   ↳ hep-phhep-latnucl-thPRD(2004)·87 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.