Browsing by Author "Koutsou, Giannis"

Now showing items 21-40 of 50

    • Article  

      Investigation of light and heavy tetraquark candidates using lattice QCD 

      Wagner, M.; Abdel-Rehim, A.; Alexandrou, Constantia; Brida, M. D.; Gravina, M.; Koutsou, Giannis; Scorzato, L.; Urbach, C. (2014)
      We review the status of an ongoing long-term lattice investigation of the spectrum and structure of tetraquark candidates. We focus on the light scalar meson a0(980). First steps regarding the study of a possibly existing ...
    • Article  

      Light baryon masses with dynamical twisted mass fermions 

      Alexandrou, Constantia; Baron, R.; Blossier, B.; Brinet, M.; Carbonell, J.; Dimopoulos, Petros; Drach, V.; Farchioni, F.; Frezzotti, R.; Guichon, P.; Herdoiza, G.; Jansen, K.; Korzec, T.; Koutsou, Giannis; Liu, Z.; Michael, C.; Pène, O.; Shindler, A.; Urbach, C.; Wenger, U. (2008)
      We present results on the mass of the nucleon and the Δ using two dynamical degenerate twisted mass quarks and the tree-level Symanzik improved gauge action. The evaluation is performed at four quark masses corresponding ...
    • Article  

      Neutron electric dipole moment using Nf=2+1+1 twisted mass fermions 

      Petschlies, Marcus; Alexandrou, Constantia; Athenodorou, A.; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Jansen, K.; Koutsou, Giannis; Ottnad, K. (2016)
      We evaluate the neutron electric dipole moment |d→N| using lattice QCD techniques. The gauge configurations analyzed are produced by the European Twisted Mass Collaboration using Nf=2+1+1 twisted mass fermions at one value ...
    • Article  

      Nucleon and pion structure with lattice QCD simulations at physical value of the pion mass 

      Abdel-Rehim, A.; Alexandrou, Constantia; Constantinou, Martha; Dimopoulos, Petros; Frezzotti, R.; Hadjiyiannakou, Kyriakos; Jansen, K.; Kallidonis, Christos; Kostrzewa, B.; Koutsou, Giannis; Mangin-Brinet, M.; Oehm, M.; Rossi, G. C.; Urbach, C.; Wenger, U. (2015)
      We present results on the nucleon scalar, axial, and tensor charges as well as on the momentum fraction, and the helicity and transversity moments. The pion momentum fraction is also presented. The computation of these key ...
    • 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 ...
    • Article  

      Nucleon electromagnetic form factors from lattice QCD 

      Alexandrou, Constantia; Koutsou, Giannis; Negele, J. W.; Tsapalis, Antonios (2006)
      We evaluate the isovector nucleon electromagnetic form factors in quenched and unquenched QCD on the lattice using Wilson fermions. In the quenched theory we use a lattice of spatial size 3 fm at β=6.0 enabling us to reach ...
    • Article  

      Nucleon electromagnetic form factors using lattice simulations at the physical point 

      Alexandrou, Constantia; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Jansen, K.; Kallidonis, Christos; Koutsou, Giannis; Vaquero Aviles-Casco, A. (2017)
      We present results for the nucleon electromagnetic form factors using an ensemble of maximally twisted mass clover-improved fermions with pion mass of about 130 MeV. We use multiple sink-source separations and three analysis ...
    • Article  

      Nucleon excited states in N f = 2 lattice QCD 

      Alexandrou, Constantia; Korzec, T.; Koutsou, Giannis; Leontiou, Theodoros (2014)
      We investigate the excited states of the nucleon using Nf=2 twisted mass gauge configurations with pion masses in the range of about 270 to 450 MeV and one ensemble of Nf=2 Clover fermions at almost physical pion mass. We ...
    • Article  

      Nucleon form factors and moments of generalized parton distributions using Nf=2+1+1 twisted mass fermions 

      Alexandrou, Constantia; Constantinou, Martha; Dinter, S.; Drach, V.; Jansen, K.; Kallidonis, Christos; Koutsou, Giannis (2013)
      We present results on the axial and the electromagnetic form factors of the nucleon, as well as on the first moments of the nucleon generalized parton distributions using maximally twisted mass fermions. We analyze two N ...
    • Conference Object  

      Nucleon form factors with NF=2 twisted mass fermions 

      Guichon, P.; Baron, R.; Alexandrou, Constantia; Korzec, T.; Koutsou, Giannis; Brinet, M.; Carbonell, J.; Harraud, P. -A; Jansen, K. (2010)
      We present results on the nucleon form factors using two degenerate flavors of twisted mass fermions on 243×48 and 32×64 lattices with pion masses in the range 290÷485MeV. © 2010 American Institute of Physics.
    • 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 ...
    • Article  

      Nucleon scalar and tensor charges using lattice QCD simulations at the physical value of the pION mass 

      Alexandrou, Constantia; Constantinou, Martha; Dimopoulos, Petros; Frezzotti, R.; Hadjiyiannakou, Kyriakos; Jansen, K.; Kallidonis, Christos; Kostrzewa, B.; Koutsou, Giannis; Mangin-Brinet, M.; Vaquero Avilès-Casco, A.; Wenger, U. (2017)
      We present results on the light, strange and charm nucleon scalar and tensor charges from lattice QCD, using simulations with Nf=2 flavors of twisted mass clover-improved fermions with a physical value of the pION mass. ...
    • 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 ...
    • Article  

      Nucleon structure using lattice QCD 

      Alexandrou, Constantia; Constantinou, Martha; Drach, V.; Hadjiyiannakou, Kyriakos; Jansen, K.; Kallidonis, Christos; Koutsou, Giannis; Leontiou, Theodoros; Vaquero, A. (2013)
      A review of recent nucleon structure calculations within lattice QCD is presented. The nucleon excited states, the axial charge, the isovector momentum fraction and helicity distribution are discussed, assessing the methods ...
    • Article  

      Nucleon to delta electromagnetic transition form factors in lattice QCD 

      Alexandrou, Constantia; Koutsou, Giannis; Neff, H.; Negele, J. W.; Schroers, W.; Tsapalis, Antonios (2008)
      The electromagnetic nucleon to Δ transition form factors are evaluated using two degenerate flavors of dynamical Wilson fermions and using dynamical sea staggered fermions with domain-wall valence quarks. The two subdominant ...
    • Article  

      Nucleon to Δ transition form factors with NF=2+1 domain wall fermions 

      Alexandrou, Constantia; Koutsou, Giannis; Negele, J. W.; Proestos, Y.; Tsapalis, Antonios (2011)
      We calculate the electromagnetic, axial, and pseudoscalar form factors of the nucleon to Δ(1232) transition using two dynamical light degenerate quarks and a dynamical strange quark simulated with the domain wall fermion ...
    • Article  

      The pentaquark potential, mass and density-density correlator 

      Alexandrou, Constantia; Koutsou, Giannis; Tsapalis, Antonios (2005)
      We evaluate the static qqqqq̄ potential in the quenched theory at β = 5.8 and β = 6.0 on a lattice of size 163 × 32. The mass and density-density correlator for the Θ+ is investigated in the quenched theory at β = 6.0 on ...
    • 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  

      Position space method for the nucleon magnetic moment in lattice QCD 

      Petschlies, Marcus; Alexandrou, Constantia; Constantinou, Martha; Koutsou, Giannis; Ottnad, K. (2016)
      The extraction of the magnetic form factor of the nucleon at zero momentum transfer is usually performed by adopting a parametrization for its momentum dependence and fitting the results obtained at finite momenta. We ...
    • Conference Object  

      The quark contents of the nucleon and their implication for dark matter search 

      Alexandrou, Constantia; Constantinou, Martha; Drach, V.; Hadjiyiannakou, Kyriakos; Jansen, K.; Koutsou, Giannis; Strelchenko, A.; Vaquero, A. (Proceedings of Science (PoS), 2013)
      We present results concerning the light and strange quark contents of the nucleon using Nf = 2+1+1 flavours of maximally twisted mass fermions. The corresponding σ- Terms are casting light on the origin of the nucleon mass ...