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We present a calculation of the scalar, vector and tensor pion and kaon form factors using one ensemble of two degenerate light, a strange and a charm quark ($N_f=2+1+1$) of maximally twisted mass fermions with clover improvement. The quark…

We present results on the electroweak form factors and on the lower moments of parton distributions of the nucleon, within lattice QCD using two dynamical flavors of degenerate twisted mass fermions. Results are obtained on lattices with…

High Energy Physics - Lattice · Physics 2012-01-04 C. Alexandrou , M. Brinet , J. Carbonell , M. Constantinou , P. Guichon , P. A. Harraud , K. Jansen , C. Kallidonis , T. Korzec , M. Papinutto

The sea quark contributions to the nucleon electromagnetic form factors from up, down and strange quarks are studied with the nonlocal chiral effective Lagrangian. Both octet and decuplet intermediate states are included in the one loop…

High Energy Physics - Phenomenology · Physics 2020-09-21 Ming-Yang Yang , Ping Wang

We present results for the nucleon electromagnetic form factors, including the momentum transfer dependence and derived quantities (charge radii and magnetic moment). The analysis is performed using O(a) improved Wilson fermions in Nf=2 QCD…

High Energy Physics - Lattice · Physics 2015-09-30 S. Capitani , M. Della Morte , D. Djukanovic , G. von Hippel , J. Hua , B. Jäger , B. Knippschild , H. B. Meyer , T. D. Rae , H. Wittig

We calculate the strange magnetic moment of the nucleon on a quenched $16^3 \times 24$ lattice at $\beta = 6.0$, and with Wilson fermions at $\kappa$ = 0.148, 0.152, and 0.154. The strange quark contribution from the disconnected insertion…

High Energy Physics - Lattice · Physics 2009-10-31 Nilmani Mathur , Shao-Jing Dong

We review a recent theoretical determination of the strange quark content of the electromagnetic form factors of the nucleon. These are compared with a global analysis of current experimental measurements in parity-violating electron…

Nuclear Theory · Physics 2008-11-26 Ross D. Young

We compute electroweak form factors of the nucleon and photon transition form factors of non-strange baryon resonances up to the third resonance region in a model with instanton-induced interaction. The calculation is based on the…

High Energy Physics - Phenomenology · Physics 2007-05-23 Dirk Merten , Ulrich Loering , Klaus Kretzschmar , Bernard Metsch , Herbert-R. Petry

In a recent study of the Lambda(1405), the suppression of the strange-quark contribution to the magnetic form factor was interpreted as the discovery of a dominant antikaon-nucleon composition for this low-lying state. We confirm this…

High Energy Physics - Lattice · Physics 2017-04-05 Jonathan M. M. Hall , Waseem Kamleh , Derek B. Leinweber , Benjamin J. Menadue , Benjamin J. Owen , Anthony W. Thomas

We compute the disconnected quark loops contributions entering the determination of nucleon observables, by using a $N_f = 2$ ensemble of twisted mass fermions with a clover term at a pion mass $m_\pi = 133$ MeV. We employ exact deflation…

We compute the electromagnetic form factors of the nucleon in the Poincare-covariant Faddeev framework based on the Dyson-Schwinger equations of QCD. The general expression for a baryon's electromagnetic current in terms of three…

High Energy Physics - Phenomenology · Physics 2011-08-08 Gernot Eichmann

Results are presented on the neutron electric dipole moment using an ensemble of $N_f=2+1+1$ twisted mass clover-improved fermions with lattice spacing of $a\simeq 0.08$ fm and physical pion mass ($m_\pi\simeq 139$ MeV). The approach…

High Energy Physics - Lattice · Physics 2021-12-14 Constantia Alexandrou , Andreas Athenodorou , Kyriakos Hadjiannakou , Antonino Todaro

The total contribution of strange quarks to the intrinsic spin of the nucleon can be determined from a measurement of the strange-quark contribution to the nucleon's elastic axial form factor. We have studied the strangeness contribution to…

High Energy Physics - Experiment · Physics 2014-05-19 S. F. Pate , J. P. Schaub , D. P. Trujillo

We investigate the electromagnetic form factors of nucleons within a simple relativistic quark spectator-diquark model using the light-cone formalism. Melosh rotations are applied to both quark and vector diquark. It is shown that the…

High Energy Physics - Phenomenology · Physics 2009-11-07 Bo-Qiang Ma , Di Qing , Ivan Schmidt

We evaluate the isovector nucleon electromagnetic form factors in quenched and full QCD on the lattice using Wilson fermions. In the quenched theory we use a lattice of spatial size 3 fm at beta=6.0 enabling us to reach low momentum…

High Energy Physics - Lattice · Physics 2008-11-26 C. Alexandrou , G. Koutsou , J. W. Negele , A. Tsapalis

The charged and neutral kaon form factors are calculated as a phenomenological application of the QCD Dyson-Schwinger equations. The results are compared with the pion form factor calculated in the same framework and yield…

Nuclear Theory · Physics 2010-03-04 C. J. Burden , C. D. Roberts , M. J. Thomson

We present the first calculation of the pion electromagnetic form factor at physical light quark masses. This form factor parameterises the deviations from the behaviour of a point-like particle when a photon hits the pion. These deviations…

High Energy Physics - Lattice · Physics 2017-10-23 Jonna Koponen , Francis Bursa , Christine T. H. Davies , Rachel J. Dowdall , G. Peter Lepage

Recent progress in lattice QCD calculations of nucleon structure will be presented. Calculations of nucleon matrix elements and form factors have long been difficult to reconcile with experiment, but with advances in both methodology and…

High Energy Physics - Lattice · Physics 2016-01-29 Jeremy Green

The spin decomposition of the proton is a long-standing topic of much interest in hadronic physics. Lattice QCD has had much success in calculating the connected contributions to the quark spin. However, complete calculations, which…

High Energy Physics - Lattice · Physics 2016-01-06 A. J. Chambers , R. Horsley , Y. Nakamura , H. Perlt , D. Pleiter , P. E. L. Rakow , G. Schierholz , A. Schiller , H. Stüben , R. D. Young , J. M. Zanotti

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 evaluate the…

We present results on the quark unpolarized, helicity and transversity parton distributions functions of the nucleon. We use the quasi-parton distribution approach within the lattice QCD framework and perform the computation using an…

High Energy Physics - Lattice · Physics 2021-09-22 Constantia Alexandrou , Martha Constantinou , Kyriakos Hadjiyiannakou , Karl Jansen , Floriano Manigrasso