相关论文: Nucleon strange quark content in 2+1-flavor QCD
The role of the quark condensate in low-energy QCD and its behaviour in nuclear matter are discussed. Partial restoration of chiral symmetry, as indicated by a reduction of the quark condensate in matter, could significantly alter the…
We report on a new fully differential calculation of the next-to-next-to-leading-order (NNLO) QCD radiative corrections to the production of top-quark pairs at hadron colliders. The calculation is performed by using the $q_T$ subtraction…
We discuss analytic continuation as a tool to extract the cumulants of the quark number fluctuations in the strongly interacting medium from lattice QCD simulations at imaginary chemical potentials. The method is applied to $N_f = 2+1$ QCD,…
We present state-of-the-art results for the matrix elements of flavor diagonal tensor operators within the nucleon state. The calculation of the dominant connected contribution is done using eleven ensembles of gauge configurations…
We report a lattice QCD calculation of the strange quark contribution to the nucleon's magnetic moment and charge radius. This analysis presents the first direct determination of strange electromagnetic form factors including at the…
We present state-of-the-art results from a lattice QCD calculation of the nucleon axial coupling, $g_A$, using M\"obius Domain-Wall fermions solved on the dynamical $N_f = 2 + 1 + 1$ HISQ ensembles after they are smeared using 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…
We analyze (using a chiral effective Lagrangian model) the scalar and pseudoscalar meson mass spectrum of QCD at finite temperature, above the chiral transition at $T_c$, looking, in particular, for signatures of a possible breaking of the…
We give an update on our ongoing efforts to compute the nucleon's form factors and moments of structure functions using Nf=2 flavours of non-perturbatively improved Clover fermions. We focus on new results obtained on gauge configurations…
Recent results for the QCD phase structure at finite temperature and light-quark chemical potential are summarized, where the cases of N_f = 2 + 1 and N_f = 2+1+1 dynamical quark flavors are considered. Order parameters for the chiral and…
We investigate the transverse quark spin densities of the nucleon with the lowest moment within the framework of the SU(3) chiral quark-soliton model, emphasizing the strange quark spin density. Based on previous results of the vector and…
Non-perturbative QCD vacuum effects at finite density are parametrized by means of a bag constant $B$. It is extracted from a Nambu- Jona Lasinio model with two or three flavors. The parameter $B$ is used in an effective quark-meson…
We derive QCD sum rules from the nucleon two-point function in nuclear medium, calculating its specral function in chiral perturbation theory to one loop. Our calculation shows the inadequacy of the commonly used ansatz to represent the…
We consider the matrix elements of the left-handed flavor-conserving four-quark operators in the nucleon and pion states. Using chiral symmetry, we derive relationships among these matrix elements. We argue that the $\Delta I = 1/2$ rule of…
Non-compact three-dimensional QED is studied by computer simulations to understand its chiral symmetry breaking features for different values of the number of fermion flavors N_f. We consider the four-component formulation for the fermion…
We report on the first fully differential calculation of the next-to-next-to-leading-order (NNLO) QCD radiative corrections to the production of bottom-quark pairs at hadron colliders. The calculation is performed by using the $q_T$…
We compute the condensate in QCD with a single quark flavor using numerical simulations with the overlap formulation of lattice fermions. The condensate is extracted by fitting the distribution of low lying eigenvalues of the Dirac operator…
It is imperative that lattice QCD serve to develop our understanding of hadron structure and, where possible, to guide the interpretation of experimental data. There is now a great deal of effort directed at the calculation of the…
Exploiting the recent lattice results for the infrared gluon propagator with light dynamical quarks, we solve the gap equation for the quark propagator. We thus model the chiral symmetry breaking mechanism with increasing number of flavours…
Intrinsic strangeness contributions to low-energy strange quark matrix elements of the nucleon are modelled using kaon loops and meson-nucleon vertex functions taken from nucleon-nucleon and nucleon-hyperon scattering. A comparison with…