Browsing by Subject "Lattice theory"

Now showing items 1-20 of 29

    • Conference Object  

      Calculation of the decay width of decuplet baryons 

      Petschlies, Marcus; Alexandrou, Constantia; Negele, J. W.; Pochinsky, A. V.; Syritsyn, S. S. (Proceedings of Science (PoS), 2015)
      We calculate the coupling constant and decay width of the decuplet to octet baryon transitions in lattice QCD using the transfer matrix method. The transition amplitude is related to the coupling constant and via the Fermi's ...
    • 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 ...
    • Conference Object  

      The chromomagnetic operator on the lattice 

      Constantinou, Martha G.; Costa, M. G.; Frezzotti, R.; Lubicz, V.; Martinelli, G.; Meloni, D.; Panagopoulos, Haralambos G.; Simula, S. (Proceedings of Science (PoS), 2013)
      We study matrix elements of the "chromomagnetic" operator on the lattice. This operator is contained in the strangeness-changing effective Hamiltonian which describes electroweak effects in the Standard Model and beyond. ...
    • Conference Object  

      Computation of correlation matrices for tetraquark candidates with Jp = 0+ and flavor structure q1q2q3q3 

      Berlin, J.; Abdel-Rehim, A.; Alexandrou, Constantia; Dalla Brida, M.; Gravina, M.; Wagner, M. (Proceedings of Science (PoS), 2015)
      The conjecture that several recently observed mesons have a structure, which is not dominated by an ordinary quark-Antiquark pair, but by a four-quark structure, is being actively investigated both theoretical and ...
    • Conference Object  

      Computation of disconnected contributions to nucleon observables 

      Alexandrou, Constantia; Drach, V.; Jansen, K.; Koutsou, Giannis; Avilés-Casco, A. V. (Proceedings of Science (PoS), 2013)
      We compare several methods for computing disconnected fermion loops contributing to nucleon three-point functions. The comparison is carried out using one ensemble of Nf =2+1+1 twisted mass fermions with pion mass of 373 ...
    • Conference Object  

      DDalphaAMG for twisted mass fermions 

      Bacchio, S.; Alexandrou, Constantia; Finkenrath, J.; Frommer, A.; Kahl, K.; Rottmann, M. (Proceedings of Science (PoS), 2016)
      We present the Adaptive Aggregation-based Domain Decomposition Multigrid method extended to the twisted mass fermion discretization action. We show comparisons of results as a function of tuning the parameters that enter ...
    • Conference Object  

      Determination of the Δ resonance width from lattice QCD 

      Petschlies, Marcus; Alexandrou, Constantia; Negele, J. W. (Proceedings of Science (PoS), 2013)
      A method suitable for extracting resonance parameters of unstable baryons in lattice QCD is examined. The method is applied to the strong decay of the Δ to a pion-nucleon state, extracting the pND coupling constant and Δ ...
    • Conference Object  

      Disconnected diagrams with twisted-mass fermions 

      Abdel-Rehim, A.; Alexandrou, Constantia; Constantinou, Martha; Finkenrath, J.; Hadjiyiannakou, Kyriakos; Jansen, K.; Kallidonis, Christos; Koutsou, Giannis; Avilés-Casco, A. V.; Volmer, J. (Proceedings of Science (PoS), 2016)
      The latest results from the Twisted-Mass collaboration on disconnected diagrams at the physical value of the pion mass are presented. In particular, we focus on the sigma terms, the axial charges and the momentum fraction, ...
    • Conference Object  

      Disconnected quark loop contributions to nucleon observables using Nf = 2 twisted clover fermions at the physical value of the light quark mass 

      Abdel-Rehim, A.; Alexandrou, Constantia; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Jansen, K.; Kallidonis, Christos; Koutsou, Giannis; Avilés-Casco, A. V. (Proceedings of Science (PoS), 2015)
      We compute the disconnected quark loops contributions entering the determination of nucleon observables, by using a Nf = 2 ensemble of twisted mass fermions with a clover term at a pION mass mπ = 133 MeV. We employ exact ...
    • Article  

      Effect of silicon nitride/oxide on the structure and the thermal conductivity of CoSi nanocomposites 

      Ioannou, M.; Delimitis, A.; Symeou, E.; Giapintzakis, John; Kyratsi, Theodora (2017)
      In this work, the fabrication of nanocomposites with silicon nitride/oxide into the thermoelectric matrix of cobalt silicide is presented. The different concentrations of nano-Si3N4 were intentionally introduced by mechanical ...
    • Conference Object  

      The electric dipole moment of the neutron from Nf = 2+1+1 twisted mass fermions 

      Petschlies, Marcus; Alexandrou, Constantia; Athenodorou, A.; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Jansen, K.; Koutsou, Giannis; Ottnad, K. (Proceedings of Science (PoS), 2015)
      We extract the neutron electric dipole moment (nEDM) dn on configurations produced with Nf = 2+1+1 twisted mass fermions with lattice spacing of a ≃ 0.082fm and a light quark mass that correpsonds to Mπ ≃ 373 MeV. We do ...
    • Conference Object  

      Implementation of the twisted mass fermion operator in the QUDA library 

      Strelchenko, A.; Alexandrou, Constantia; Koutsou, Giannis; Avilés-Casco, A. V. (Proceedings of Science (PoS), 2013)
      We discuss an extension of the QUDA library for the Wilson twisted mass operator. A performance analysis is presented for both degenerate and non-degenerate flavor doublets. The degenerate twisted mass fermion operator ...
    • Conference Object  

      Importance of closed quark loops for lattice QCD studies of tetraquarks 

      Berlin, J.; Abdel-Rehim, A.; Alexandrou, Constantia; Brida, M. D.; Finkenrath, J.; Gravina, M.; Leontiou, Theodoros; Wagner, M. (Proceedings of Science (PoS), 2016)
      To investigate the light scalar tetraquark candidate a0(980) (quantum numbers JP =0+), a correlation matrix including a variety of two- and four-quark interpolating operators has to be computed. We discuss efficient ...
    • Conference Object  

      Looking at the gluon moment of the nucleon with dynamical twisted mass fermions 

      Alexandrou, Constantia; Drach, V.; Hadjiyiannakou, Kyriakos; Jansen, K.; Kostrzewa, B.; Wiese, C. (Proceedings of Science (PoS), 2013)
      To understand the structure of hadrons it is important to know the PDF of their constituents, the quarks and gluons. In our work we aim to compute the first moment of the gluon PDF h(x)ig for the nucleon. We follow two ...
    • Doctoral Thesis  

      Multiple Hamiltonian structures for Volterra and Toda Lattices 

      Kouzaris, Stelios (Πανεπιστήμιο Κύπρου, Σχολή Θετικών και Εφαρμοσμένων Επιστημών/ University of Cyprus, Faculty of Pure and Applied Sciences, 2001)
      Η διατριβή χωρίζεται σε δύο μέρη. Στο πρώτο μέρος μελετούμε τα ολοκληρώσιμα συστήματα που κατασκεύαστηκαν από τον Bogoyavlensky το 1988. Αυτά τα συστήματα συνδέονται με απλές Lie άλγεβρες και γενικεύουν το καλά γνωστό ...
    • Conference Object  

      Nucleon electromagnetic and axial form factors with Nf=2 twisted mass fermions at the physical point 

      Alexandrou, Constantia; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Kallidonis, Christos; Koutsou, Giannis; Jansen, K.; Ottnad, K.; Vaquero, A. (Proceedings of Science (PoS), 2016)
      We present results for the nucleon electromagnetic and axial form factors using an Nf=2 twisted mass fermion ensemble with pion mass of about 131 MeV. We use multiple sink-source separations to identify excited state ...
    • Conference Object  

      Nucleon generalized form factors with twisted mass fermions 

      Alexandrou, Constantia; Constantinou, Martha; Drach, V.; Jansen, K.; Kallidonis, Christos; Koutsou, Giannis (Proceedings of Science (PoS), 2013)
      We present results on the nucleon form factors, momentum fraction and helicity moment for Nf = 2 and Nf = 2+1+1 twisted mass fermions for a number of lattice volumes and lattice spacings. First results for a new Nf = 2 ...
    • Conference Object  

      Nucleon spin and quark content at the physical point 

      Alexandrou, Constantia; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Kallidonis, Christos; Koutsou, Giannis; Jansen, K.; Wiese, C.; Avilés-Casco, A. V. (Proceedings of Science (PoS), 2016)
      We present results on the spin and quark content of the nucleon using Nf =2 twisted mass cloverimproved fermion simulations with a pion mass close to its physical value. We use recently developed methods to obtain accurate ...
    • 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  

      Perturbative renormalization of staggered fermion operators with stout improvement: Application to the magnetic susceptibility of QCD 

      Bali, G. S.; Bruckmann, F.; Constantinou, Martha; Costa, Marios Gil; Endrödi, Gergely; Katz, Sándor D.; Panagopoulos, Haralambos G.; Schäfer, A. (Proceedings of Science (PoS), 2013)
      We calculate the fermion propagator and the quark-antiquark Green's functions for a complete set of ultralocal fermion bilinears, Γ [Γ: scalar (S), pseudoscalar (P), vector (V), axial (A) and tensor (T)], using perturbation ...