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The electromagnetic and axial form factors of the nucleon are evaluated in twisted mass QCD with two degenerate flavors of light, dynamical quarks. The axial charge g_A, magnetic moment and the Dirac and Pauli radii are determined for pion…

We present results for the nucleon electromagnetic and axial form factors using an N$_f$=2 twisted mass fermion ensemble with pion mass of about 131 MeV. We use multiple sink-source separations to identify excited state contamination.…

We present results on the nucleon form factors, momentum fraction and helicity moment for $N_f=2$ and $N_f=2+1+1$ twisted mass fermions for a number of lattice volumes and lattice spacings. First results for a new $N_f=2$ ensemble at the…

High Energy Physics - Lattice · Physics 2013-12-11 C. Alexandrou , M. Constantinou , V. Drach , K. Jansen , Ch. Kallidonis , G. Koutsou

We present results on the nucleon tensor form factors and first moment of the transversity distribution using maximally twisted mass fermions. We analyze two Nf=2+1+1 ensembles having pion masses of 213 MeV and 373 MeV with lattice spacing…

High Energy Physics - Lattice · Physics 2013-11-20 Constantia Alexandrou , Martha Constantinou , Karl Jansen , Giannis Koutsou , Haralambos Panagopoulos

We present results on the masses of the low-lying baryons using ten ensembles of gauge configurations with $N_f =2+1+1$ dynamical twisted mass fermions, at three values of the lattice spacing, spanning a pion mass range from about 210 MeV…

High Energy Physics - Lattice · Physics 2014-12-03 C. Alexandrou , V. Drach , K. Hadjiyiannakou , K. Jansen , C. Kallidonis , G. Koutsou

We investigate scalar matrix elements of the nucleon using $N_f=2+1+1$ flavors of maximally twisted mass fermions at a fixed value of the lattice spacing of $a\approx 0.078{\rm fm}$. We compute disconnected contributions to the relevant…

High Energy Physics - Lattice · Physics 2012-02-17 S. Dinter , V. Drach , K. Jansen

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 observables is…

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_f=2+1+1 ensembles…

High Energy Physics - Lattice · Physics 2013-08-09 C. Alexandrou , M. Constantinou , S. Dinter , V. Drach , K. Jansen , C. Kallidonis , G. Koutsou

We report on recent results of the QCDSF/UKQCD Collaboration on investigations of baryon structure using configurations generated with N_f=2+1 dynamical flavours of O(a) improved Wilson fermions. With the strange quark mass as an additional…

High Energy Physics - Lattice · Physics 2011-03-22 M. Göckeler , Ph. Hägler , R. Horsley , Y. Nakamura , D. Pleiter , P. E. L. Rakow , A. Schäfer , G. Schierholz , H. Stüben , F. Winter , J. M. Zanotti

The axial couplings of the low lying baryons are evaluated using a total of five ensembles of dynamical twisted mass fermion gauge configurations. The simulations are performed using the Iwasaki gauge action and two degenerate flavors of…

High Energy Physics - Lattice · Physics 2016-08-10 C. Alexandrou , K. Hadjiyiannakou , Ch. Kallidonis

We present results on the spin and quark content of the nucleon using $N_f=2$ twisted mass clover-improved fermion simulations with a pion mass close to its physical value. We use recently developed methods to obtain accurate results for…

High Energy Physics - Lattice · Physics 2016-11-29 C. Alexandrou , M. Constantinou , K. Hadjiyiannakou , Ch. Kallidonis , G. Koutsou , K. Jansen , Ch. Wiese , A. Vaquero Avilés-Casco

We present results on the electromagnetic and axial nucleon form factors using two degenerate flavors of twisted mass fermions on lattices of spatial size 2.1 fm and 2.7 fm and a lattice spacing of about 0.09 fm. We consider pion masses in…

High Energy Physics - Lattice · Physics 2010-02-05 C. Alexandrou , T. Korzec , G. Koutsou , R. Baron , P. Guichon , M. Brinet , J. Carbonell , P. -A. Harraud , K. Jansen

We present results for the light, strange and charm quark masses using $N_f=2+1+1$ twisted mass fermion ensembles at three values of the lattice spacing, including two ensembles simulated with the physical value of the pion mass. The…

We present results for the $\sigma$-terms and axial charges for various hyperons and charmed baryons using $N_f=2+1+1$ twisted mass fermions. For the computation of the three-point function we use the fixed current method. For one of the…

High Energy Physics - Lattice · Physics 2014-04-28 C. Alexandrou , K. Hadjiyiannakou , K. Jansen , Ch. Kallidonis

We present preliminary results for the axial and tensor charge of the nucleon obtained from simulations with N_f=2 clover fermions. A comparison with chiral perturbation theory is attempted.

We determine the nucleon axial, scalar and tensor charges at the continuum limit by analyzing three $N_f=2+1+1$ twisted mass fermion ensembles with all quark masses tuned to approximately their physical values. We include all contributions…

High Energy Physics - Lattice · Physics 2025-02-11 Constantia Alexandrou , Simone Bacchio , Jacob Finkenrath , Christos Iona , Giannis Koutsou , Yan Li , Gregoris Spanoudes

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, all of them for…

Results on the electromagnetic form factors of the nucleon using twisted mass fermion configurations are presented. These include a gauge field ensemble simulated with two degenerate light quarks yielding a pion mass of around 130 MeV, as…

We present physics results from simulations of QCD using $N_f = 2$ dynamical Wilson twisted mass fermions at the physical value of the pion mass. These simulations were enabled by the addition of the clover term to the twisted mass quark…

The axial vector and tensor charge, defined as the first moments of the forward nucleon matrix elements of corresponding quark currents, are essential for characterizing the spin structure of the nucleon. However, the transversity…

High Energy Physics - Phenomenology · Physics 2009-11-07 Leonard Gamberg , Gary R. Goldstein
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