Πλοήγηση ανά Συγγραφέα "Vicari, E."

Αποτελέσματα 1-20 από 36

    • Article  

      The 3-loop beta function of QCD 

      Allés, B.; Christou, Chris; Feo, A.; Panagopoulos, Haralambos G.; Vicari, E. (1997)
      Using the background field technique, we calculate the 3-loop beta function of lattice SU (N) gauge theories. In the pure gluonic case, we present our results, comparing to those recently obtained by Luescher and Weisz. ...
    • Article  

      The 4D SU(3) gauge theory with an imaginary θ term 

      Panagopoulos, Haralambos G.; Vicari, E. (2011)
      We study the scaling behavior of the 4D SU(3) lattice gauge theory in the presence of a θ term, by Monte Carlo simulations computing the topological properties at imaginary θ. The numerical results provide a good evidence ...
    • Article  

      Change of θ dependence in 4D SU(N) gauge theories across the deconfinement transition 

      Bonati, C.; D'Elia, M.; Panagopoulos, Haralambos G.; Vicari, E. (2013)
      We study the dependence of 4D SU(N) gauge theories on the topological θ term at finite temperature T. We exploit the lattice formulation of the theory, presenting numerical results for the expansion of the free energy up ...
    • Article  

      Confining strings in representations with common n-ality 

      Del Debbio, L.; Vicari, E.; Panagopoulos, Haralambos G. (2003)
      We study the spectrum of confining strings in SU(3) pure gauge theory, by means of lattice Monte Carlo simulations, using torelon operators in different representations of the gauge group. Our results provide direct evidence ...
    • Article  

      Cooling and the string tension in lattice gauge theories 

      Campostrini, M.; Di Giacomo, A.; Maggiore, M.; Panagopoulos, Haralambos G.; Vicari, E. (1989)
      We explore the possibility of improving the determination of the string tension using the cooling method. We present preliminary results for the gauge group SU(2): We find that statistical errors are drastically reduced ...
    • Article  

      Free energy and θ dependence of SU (N) gauge theories 

      Del Debbio, L.; Panagopoulos, Haralambos G.; Vicari, E. (2003)
      We study the dependence of the free energy on the CP violating angle θ, in four-dimensional SU(N) gauge theories with N ≥ 3, and in the large-N limit. Using the Wilson lattice formulation for numerical simulations, we ...
    • Article  

      Improved lattice operators: Case of the topological charge density 

      Christou, Chris; Di Giacomo, A.; Panagopoulos, Haralambos G.; Vicari, E. (1996)
      We analyze the properties of a class of improved lattice topological charge density operators, constructed by a smearinglike procedure. By optimizing the choice of the parameters introduced in their definition we find ...
    • Article  

      Improving the topological charge density operator on the lattice 

      Christou, Chris; Di Giacomo, A.; Panagopoulos, Haralambos G.; Vicari, E. (1996)
      We analyze the properties of a class of improved lattice topological charge density operators, constructed by a smearing-like procedure. By optimizing the choice of the parameters introduced in their definition, we find ...
    • Article  

      K-string tensions in SU(N) gauge theories 

      Debbio, L. D.; Panagopoulos, Haralambos G.; Rossi, P.; Vicari, E. (2002)
      In the context of four-dimensional SU(AO gauge theories, we study the spectrum of the confining strings. We compute, for the SU(6) gauge theory formulated on a lattice, the three independent string tensions σk related to ...
    • Article  

      K-string tensions in SU(N) gauge theories 

      Del Debbio, L.; Panagopoulos, Haralambos G.; Rossi, P.; Vicari, E. (2002)
      In the context of four-dimensional SU(N) gauge theories, we study the spectrum of the confining strings. We compute, for the SU(6) gauge theory formulated on a lattice, the three independent string tensions σk related to ...
    • Article  

      N-ality and topology at finite temperature 

      Del Debbio, I.; Panagopoulos, Haralambos G.; Vicari, E. (2005)
      We study [JHEP 0309 (2003) 034] the spectrum of confining strings in SU(3) pure gauge theory, in different representations of the gauge group. Our results provide direct evidence that the string spectrum agrees with ...
    • Article  

      Off-equilibrium scaling behaviors across first-order transitions 

      Panagopoulos, Haralambos G.; Vicari, E. (2015)
      We study off-equilibrium behaviors at first-order transitions (FOTs) driven by a time dependence of the temperature across the transition point Tc, such as the linear behavior T(t)/Tc=1±t/ts where ts is a time scale. In ...
    • Article  

      One-loop renormalization of fermionic currents with the overlap-Dirac operator 

      Alexandrou, Constantia; Follana, E.; Panagopoulos, Haralambos G.; Vicari, E. (2000)
      We compute the one-loop lattice renormalization of the two-quark operators ψ̄Γψ, where Γ denotes the generic Dirac matrix, for the lattice formulation of QCD using the overlap-Dirac operator. We also study the renormalization ...
    • Article  

      The proton matrix element of the topological charge in quenched QCD 

      Allés, B.; Campostrini, M.; Del Debbio, L.; Di Giacomo, A.; Panagopoulos, Haralambos G.; Vicari, E. (1994)
      We compute on the lattice the on-shell proton matrix element of the topological charge density in the quenched approximation. Our calculation makes use of a nonperturbative means of determining the multiplicative renormalization ...
    • Article  

      Resummation of cactus diagrams in lattice QCD 

      Panagopoulos, Haralambos G.; Vicari, E. (1998)
      We show how to perform a resummation, to all orders in perturbation theory, of a certain class of gauge-invariant diagrams in lattice QCD. These diagrams are often largely responsible for lattice artifacts. Our resummation ...
    • Article  

      Resummation of cactus diagrams in lattice QCD, to all orders 

      Panagopoulos, Haralambos G.; Vicari, E. (2000)
      We show how to perform a resummation, to all orders in perturbation theory, of a certain class of gauge invariant tadpole-like diagrams in Lattice QCD. These diagrams are often largely responsible for lattice artifacts. ...
    • Article  

      Resummation of cactus diagrams in the clover improved lattice formulation of QCD 

      Panagopoulos, Haralambos G.; Vicari, E. (1999)
      We extend to the clover improved lattice formulation of QCD the resummation of cactus diagrams, i.e., a certain class of tadpole-like gauge invariant diagrams. Cactus resummation yields an improved perturbative expansion. ...
    • Article  

      The scale dependence of lattice condensates 

      Giacomo, A. D.; Panagopoulos, Haralambos G.; Vicari, E. (1990)
      We show how to extract the condensates of composite operators, defined with respect to some scale μ, from explicitly μ-independent Monte Carlo results, using the renormalization group. For each composite operator, the ...
    • Article  

      Simulating a CP-violating topological term in gauge theories 

      Panagopoulos, Haralambos G.; Vicari, E. (2012)
      We present recent results on the θ-dependence of four-dimensional SU(N) gauge theories, where θ is the coefficient of the CP-violating topological term in the Lagrangian. In particular, we study the scaling behavior of ...
    • Article  

      Spectrum of confining strings in SU(N) gauge theories 

      Del Debbio, L.; Panagopoulos, Haralambos G.; Rossi, P.; Vicari, E. (2002)
      We study the spectrum of the confining strings in four-dimensional SU(N) gauge theories. We compute, for the SU(4) and SU(6) gauge theories formulated on a lattice, the string tensions σk related to sources with ZN charge ...