Browsing by Author "Abdel-Rehim, A."

Now showing items 1-13 of 13

    • 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 ...
    • Article  

      Direct Evaluation of the Quark Content of Nucleons from Lattice QCD at the Physical Point 

      Abdel-Rehim, A.; Alexandrou, Constantia; Constantinou, Martha; Hadjiyiannakou, Kyriakos; Jansen, K.; Kallidonis, Christos; Koutsou, Giannis; Avilés-Casco, A. V. (2016)
      We evaluate the light, strange, and charm scalar content of the nucleon using one lattice QCD ensemble generated with two degenerate light quarks with mass fixed to their physical value. We use improved techniques to ...
    • 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, ...
    • Article  

      Disconnected quark loop contributions to nucleon observables in lattice QCD 

      Abdel-Rehim, A.; Alexandrou, Constantia; Constantinou, Martha; Drach, V.; Hadjiyiannakou, Kyriakos; Jansen, K.; Koutsou, Giannis; Vaquero, A. (2014)
      We perform a high statistics calculation of disconnected fermion loops on graphics processing units for a range of nucleon matrix elements extracted using lattice QCD. The isoscalar electromagnetic and axial vector form ...
    • 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  

      Erratum: Nucleon and pion structure with lattice QCD simulations at physical value of the pion mass (Physical Review D - Particles, Fields, Gravitation and Cosmology (2015) 92 (114513)) 

      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. (2016)
      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 ...
    • Article  

      First physics results at the physical pion mass from Nf=2 Wilson twisted mass fermions at maximal twist 

      Petschlies, Marcus; Abdel-Rehim, A.; Alexandrou, Constantia; Burger, F.; Constantinou, Martha; Dimopoulos, Petros; Frezzotti, R.; Hadjiyiannakou, Kyriakos; Helmes, C.; Jansen, K.; Jost, C.; Kallidonis, Christos; Knippschild, B.; Kostrzewa, B.; Koutsou, Giannis; Liu, L.; Mangin-Brinet, M.; Ottnad, K.; Pientka, G.; Rossi, G. C.; Urbach, C.; Wenger, U.; Werner, M. (2017)
      We present physics results from simulations of QCD using Nf=2 dynamical Wilson twisted mass fermions at the physical value of the pion mass. These simulations are enabled by the addition of the clover term to the twisted ...
    • 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 ...
    • Article  

      Investigating efficient methods for computing four-quark correlation functions 

      Abdel-Rehim, A.; Alexandrou, Constantia; Berlin, J.; Dalla Brida, M.; Finkenrath, J.; Wagner, M. (2017)
      We discuss and compare the efficiency of various methods, combinations of point-to-all propagators, stochastic timeslice-to-all propagators, the one-end trick and sequential propagators, to compute two-point correlation ...
    • 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  

      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  

      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 ...
    • Conference Object  

      Study of the a0(980) on the lattice 

      Wagner, M.; Abdel-Rehim, A.; Alexandrou, Constantia; Gravina, M.; Koutsou, Giannis; Brida, M. D.; Scorzato, L.; Urbach, C. (Proceedings of Science (PoS), 2013)
      We present lattice results for the a0(980) state using a variational approach with a variety of creation operators: quark- Antiquark, mesonic molecule, diquark- Antidiquark as well as two-meson type. Focus is put on recent ...