Tue·Nov 22, 2005Tuesday·November 22, 2005

1. 01*

   Perturbative Renormalisation for Low Moments of Generalised Parton Distributions with Clover Fermions

   M. Gockeler🇩🇪 · R. Horsley🇬🇧 · H. Perlt🇩🇪 · P.E.L. Rakow🇬🇧 · A. Schaefer🇩🇪 · G. Schierholz🇩🇪 · A. Schiller🇩🇪

   We present the non-forward quark matrix elements of operators with one and two covariant derivatives needed for the renormalisation of the first and second moments of generalised parton distributions in one-loop lattice perturbation theory using clover fermions. For some representations of the hypercubic group commonly used in simulations we define the sets of possible mixing operators and compute the one-loop mixing matrices of renormalisation factors. Tadpole improvement is applied to the results and some numerical examples are presented.

   hep-latNucl.Phys.B Proc.Suppl.(2006)·1 citation
2. 02*

   Running couplings in equivariantly gauge-fixed SU(N) Yang--Mills theories

   Maarten Golterman🇺🇸 · Yigal Shamir🇮🇱

   In equivariantly gauge-fixed SU(N) Yang--Mills theories, the gauge symmetry is only partially fixed, leaving a subgroup $H\subset SU(N)$ unfixed. Such theories avoid Neuberger's nogo theorem if the subgroup $H$ contains at least the Cartan subgroup $U(1{)}^{N-1}$, and they are thus non-perturbatively well defined if regulated on a finite lattice. We calculate the one-loop beta function for the coupling ${\tilde{g}}^2=\xi g^2$, where $g$ is the gauge coupling and $\xi$ is the gauge parameter, for a class of subgroups including the cases that $H=U(1{)}^{N-1}$ or $H=SU(M)\times SU(N-M)\times U(1)$. The coupling $\tilde{g}$ represents the strength of the interaction of the gauge degrees of freedom associated with the coset $SU(N)/H$. We find that $\tilde{g}$, like $g$, is asymptotically free. We solve the renormalization-group equations for the running of the couplings $g$ and $\tilde{g}$, and find that dimensional transmutation takes place also for the coupling $\tilde{g}$, generating a scale $\tilde{\Lambda }$ which can be larger than or equal to the scale $\Lambda$ associated with the gauge coupling $g$, but not smaller. We speculate on the possible implications of these results.

   hep-lathep-thPRD(2006)·12 citations
3. 03*

   Infrared Gluon Propagator from lattice QCD: results from large asymmetric lattices

   P. J. Silva🇵🇹 · O. Oliveira🇵🇹

   The infrared limit of the lattice Landau gauge gluon propagator is studied. We show that the lattice data is compatible with the pure power law $(q^2{)}^{2\kappa }$ solution of the Dyson-Schwinger equations. Using various lattice volumes, the infinite volume limit for the exponent $\kappa$ is measured. Although, the results allow $\kappa =0.498-0.525$, the lattice data favours $\kappa \sim 0.52$, which would imply a vanishing zero momentum gluon propagator.

   hep-lathep-phPRD(2006)·50 citations
4. 04*

   Constraining renormalon effects in lattice determination of heavy quark mass

   Taekoon Lee🇰🇷

   The Borel summation technique of infrared renormalons is applied to the lattice determination of heavy quark mass. With Borel summation a physical heavy quark pole mass and binding energy of a heavy-light meson can be defined in a rigorous and calculable manner. A notable feature of the Borel summation, compared to the usual perturbative cancellation of IR renormalons, is an automatic scale separation. The two approaches of handling renormalon divergence are compared in the B-meson as well as in an (imaginary) heavy-light meson with a mass much larger than the inverse of the lattice spacing.

   ↳ hep-phhep-latPRD(2006)·4 citations
5. 05*

   High-accuracy critical exponents of O(N) hierarchical sigma models

   J. J. Godina🇲🇽 · L. Li🇺🇸 · Y. Meurice🇺🇸 · M. B. Oktay🇮🇪

   We perform high-accuracy calculations of the critical exponent gamma and its subleading exponent for the 3D O(N) Dyson's hierarchical model, for N up to 20. We calculate the critical temperatures for the nonlinear sigma model measure. We discuss the possibility of extracting the first coefficients of the 1/N expansion from our numerical data. We show that the leading and subleading exponents agreewith Polchinski equation and the equivalent Litim equation, in the local potential approximation, with at least 4 significant digits.

   ↳ hep-thcond-mat.stat-mechhep-latPRD(2006)·5 citations
6. 06*

   Full Phase Diagram of the Massive Gross-Neveu Model

   Oliver Schnetz🇩🇪 · Michael Thies🇩🇪 · Konrad Urlichs🇩🇪

   The massive Gross-Neveu model is solved in the large N limit at finite temperature and chemical potential. The scalar potential is given in terms of Jacobi elliptic functions. It contains three parameters which are determined by transcendental equations. Self-consistency of the scalar potential is proved. The phase diagram for non-zero bare quark mass is found to contain a kink-antikink crystal phase as well as a massive fermion gas phase featuring a cross-over from light to heavy effective fermion mass. For zero bare quark mass we recover the three known phases kink-antikink crystal, massless fermion gas, and massive fermion gas. All phase transitions are shown to be of second order. Equations for the phase boundaries are given and solved numerically. Implications on condensed matter physics are indicated where our results generalize the bipolaron lattice in non-degenerate conducting polymers to finite temperature.

   ↳ hep-thcond-mat.str-elhep-lathep-phAnnals Phys.(2006)·103 citations
7. 07*

   Zero-dimensional analogue of the global gauge anomaly

   Hiroto So🇯🇵 · Hiroshi Suzuki🇯🇵

   A zero-dimensional analogue of Witten's global gauge anomaly is considered. For example, a zero-dimensional reduction of the two-dimensional $\text{SO}(2N)$ Yang-Mills theory with a single Majorana-Weyl fermion in the fundamental representation suffers from this anomaly. Another example is a zero-dimensional reduction of two- and three-dimensional $\text{SU}(2N_c)$ Yang-Mills theories which couple to a single Majorana fermion in the adjoint representation. In this case, any expectation value is either indeterminate or infinite.

   ↳ hep-thhep-latProg.Theor.Phys.(2006)·0 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.