Browsing Τμήμα Φυσικής / Department of Physics by Subject "Lattice QCD"

Now showing items 21-39 of 39

    • Article  

      Lattice investigation of the scalar mesons a0(980) and κ using four-quark operators 

      Alexandrou, Constantia; Daldrop, J. O.; Brida, M. D.; Gravina, M.; Scorzato, L.; Urbach, C.; Wagner, M. (2013)
      We carry out an exploratory study of the isospin one a0(980) and the isospin one-half κ scalar mesons using Nf = 2 + 1 + 1 Wilson twisted mass fermions at one lattice spacing. The valence strange quark is included as an ...
    • Conference Object  

      N and N to Δ transition form factors from lattice QCD 

      Alexandrou, Constantia (2007)
      We present recent lattice QCD results on nucleon form factors and N to Δ transition form factors. We predict the parity violating asymmetry in N to Δ and check the off-diagonal Goldberger-Treiman relation.
    • Conference Object  

      N to Δ electromagnetic and axial form factors in full qcd 

      Alexandrou, Constantia (2008)
      Lattice results on the N to Δ electromagnetic, axial-vector and pseudoscalar form factors are evaluated using dynamical staggered sea quarks and domain wall valence quarks for pion masses in the range of 580-350 MeV, as ...
    • Article  

      Non-perturbative renormalization of quark bilinear operators with N f = 2 (tmQCD) Wilson fermions and the tree-level improved gauge action 

      Constantinou, Martha G.; Dimopoulos, Petros; Frezzotti, R.; Herdoiza, G.; Jansen, K.; Lubicz, V.; Panagopoulos, Haralambos G.; Rossi, G. C.; Simula, S.; Stylianou, Fotos S.; Vladikas, A. (2010)
      We present results for the renormalization constants of bilinear quark operators obtained by using the tree-level Symanzik improved gauge action and the N f = 2 twisted mass fermion action at maximal twist, which guarantees ...
    • Conference Object  

      Nucleon to Δ and Δ form factors in lattice QCD 

      Alexandrou, Constantia (2012)
      We present recent lattice QCD results on the electroweak nucleon to Δ transition and Δ form factors using dynamical fermion gauge configurations with a lowest pion mass of about 300 MeV, with special emphasis in the ...
    • Article  

      O(a 2) corrections to the one-loop propagator and bilinears of clover fermions with Symanzik improved gluons 

      Constantinou, Martha G.; Lubicz, V.; Panagopoulos, Haralambos G.; Stylianou, Fotos S. (2009)
      We calculate corrections to the fermion propagator and to the Green's functions of all fermion bilinear operators of the form , to one-loop in perturbation theory. We employ the Wilson/clover action for fermions and the ...
    • 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 ...
    • Conference Object  

      Parton distributions from lattice QCD with momentum smearing 

      Alexandrou, Constantia; Cichy, K.; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Jansen, K.; Steffens, F.; Wiese, C. (Proceedings of Science (PoS), 2016)
      In this work we continue our effort to explore a recent proposal, which allows light-cone distributions to be extracted from purely spatial correlations, being thus accessible to lattice methods. In order to test the ...
    • Conference Object  

      PLQCD library for lattice QCD on multi-core machines 

      Abdel-Rehim, A.; Alexandrou, Constantia; Anastopoulos, Nikos; Koutsou, Giannis; Liabotis, A. Ioannis; Papadopoulou, Nikela (Proceedings of Science (PoS), 2013)
      PLQCD is a stand-alone software library developed under PRACE for lattice QCD. It provides an implementation of the Dirac operator for Wilson type fermions and few efficient linear solvers. The library is optimized for ...
    • Article  

      Precision study of excited state effects in nucleon matrix elements 

      Dinter, S.; Alexandrou, Constantia; Constantinou, Martha G.; Drach, V.; Jansen, K.; Renner, D. B. (2011)
      We present a dedicated analysis of the influence of excited states on the calculation of nucleon matrix elements. This calculation is performed at a fixed value of the lattice spacing, volume and pion mass that are typical ...
    • Conference Object  

      Recent results for the proton spin decomposition from lattice QCD 

      Alexandrou, Constantia; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Kallidonis, Christos; Koutsou, Giannis; Jansen, K.; Panagopoulos, Haralambos G.; Steffens, F.; Vaquero, A.; Wiese, C. (Proceedings of Science (PoS), 2016)
      The exact decomposition of the proton spin has been a much debated topic, on the experimental as well as the theoretical side. In this talk we would like to report on recent non-perturbative results and ongoing efforts to ...
    • Conference Object  

      Scalar mesons and tetraquarks by means of lattice QCD 

      Wagner, M.; Alexandrou, Constantia; Gravina, M.; Daldrop, J. O.; Urbach, C.; Brida, M. D.; Scorzato, L.; Wiese, C. (2012)
      We study the light scalar mesons a0(980) and κ using Nf = 2+1+1 flavor lattice QCD. In order to probe the internal structure of these scalar mesons, and in particular to identify, whether a sizeable tetraquark component ...
    • Article  

      Scalar mesons and tetraquarks from twisted mass lattice QCD 

      Wagner, M.; Alexandrou, Constantia; Daldrop, J. O.; Brida, M. D.; Gravina, M.; Scorzato, L.; Urbach, C.; Wiese, C. (2013)
      We study light scalar mesons with particular focus on the a 0(980) using lattice QCD with 2+1+1 dynamical quark flavors. To investigate the structure of these scalar mesons and to identify, whether a sizeable tetraquark ...
    • Article  

      The three-loop β-function of QCD with the clover action 

      Bode, Achim; Panagopoulos, Haralambos G. (2002)
      We calculate, to 3 loops in perturbation theory, the bare β-function of QCD, formulated on the lattice with the clover fermionic action. The dependence of our result on the number of colors N, the number of fermionic flavors ...
    • Article  

      The three-loop β-function of SU(N) lattice gauge theories with Wilson fermions 

      Christou, Chris; Feo, A.; Panagopoulos, Haralambos G.; Vicari, E. (1998)
      We calculate the third coefficient of the lattice β-function associated with the Wilson formulation for both gauge fields and fermions. This allows us to evaluate the three-loop correction (linear in g2 0) to the relation ...
    • Article  

      Topological susceptibility of SU(N) gauge theories at finite temperature 

      Debbio, L. D.; Panagopoulos, Haralambos G.; Vicari, E. (2004)
      We investigate the large-N behavior of the topological susceptibility χ in four-dimensional SU(N) gauge theories at finite temperature, and in particular across the finite-temperature transition at Tc. For this purpose, ...
    • Article  

      The two-loop relation between the bare lattice coupling and the MS coupling in QCD with Wilson fermions 

      Christou, Chris; Feo, A.; Panagopoulos, Haralambos G.; Vicari, E. (1998)
      We calculate the two-loop relation between the coupling renormalized in the MS̄ scheme and the bare lattice coupling g0 in QCD with Wilson fermions, extending the pure gauge results of Lüscher and Weisz. Our calculation ...
    • Article  

      Δ(1232) axial charge and form factors from lattice QCD 

      Alexandrou, Constantia; Gregory, E. B.; Korzec, T.; Koutsou, Giannis; Negele, J. W.; Sato, T.; Tsapalis, Antonios (2011)
      We present the first calculation on the Δ axial vector and pseudoscalar form factors using lattice QCD. Two Goldberger-Treiman relations are derived and examined. A combined chiral fit is performed to the nucleon axial ...
    • Article  

      λ-parameter of lattice QCD with the overlap-Dirac operator 

      Alexandrou, Constantia; Panagopoulos, Haralambos G.; Vicari, E. (2000)
      We compute the ratio ΛL/Λ/MS between the scale parameter ΛL, associated with a lattice formulation of QCD using the overlap-Dirac operator, and Λ/MS of the MS renormalization scheme. To this end, the necessary one-loop ...