Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userMoments of structure functions for $N_f=2$ near the physical point
211
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We report on our on-going study of the lower moments of iso-vector polarised and unpolarised structure functions, $g_A$ and $langle xrangle_{u-d}$, respectively, and the iso-vector scalar and tensor charge, for $N_f=2$ non-perturbatively improved clover fermions. With pion masses which go down to about 150 MeV, we investigate finite volume effects and excited state contributions.
rate research
Read More
We present an update on our results of nucleon form factors measured on a large-volume lattice $(8.1rm{fm})^4$ at almost the physical point in 2+1 flavor QCD. The configurations are generated with the stout-smeared $mathcal{O}(a)$ improved Wilson quark action and Iwasaki gauge action at $beta = 1.82$, which corresponds to the lattice spacing of 0.085 fm. The pion mass at the simulation point is about 145 MeV. We determine the iso- vector electric radius and magnetic moment from nucleon electric ($G_E$) and magnetic ($G_M$) form factors. We also report on preliminary results of the axial-vector ($F_A$), induced pseudo-scalar ($F_P$) and pseudo-scalar ($G_P$) form factors in order to verify the axial Ward- Takahashi identity in terms of the nucleon matrix elements, which may be called as the generalized Goldberger-Treiman relation.
We present results for the eta prime meson and the topological susceptibility in two flavour lattice QCD. The results are obtained using Wilson twisted mass fermions at maximal twist with pion masses ranging from 340 MeV down to the physical point. A comparison to literature values is performed giving a handle on discretisation effects.
In this paper we explore the computation of topological susceptibility and $eta$ meson mass in $N_f=2$ flavor QCD using lattice techniques with physical value of the pion mass as well as larger pion mass values. We observe that the physical point can be reached without a significant increase in the statistical noise. The mass of the $eta$ meson can be obtained from both fermionic two point functions and topological charge density correlation functions, giving compatible results. With the pion mass dependence of the $eta$ mass being flat we arrive at $M_{eta}= 772(18) mathrm{MeV}$ without an explicit continuum limit. For the topological susceptibility we observe a linear dependence on $M_pi^2$, however, with an additional constant stemming from lattice artifacts.
We present our results of the $K_{l3}$ form factors on the volume whose spatial extent is more than $L=$10 fm, with the physical pion and kaon masses using the stout-smearing clover $N_f = 2+1$ quark action and Iwasaki gauge action at $a^{-1}approx2.3$ GeV. The $K_{l3}$ form factor at zero momentum transfer is obtained from fit based on the next-to-leading (NLO) formula in SU(3) chiral perturbation theory. We estimate systematic errors of the form factor, mainly coming from the finite lattice spacing effect. We also determine the value of $|V_{us}|$ by combining our result with the experiment and check the consistency with the standard model prediction. The result is compared with the previous lattice calculations.
We present results on the isovector momentum fraction, $langle x rangle_{u-d}$, helicity moment, $langle x rangle_{Delta u-Delta d}$, and the transversity moment, $langle x rangle_{delta u-delta d}$, of the nucleon obtained using nine ensembles of gauge configurations generated by the MILC collaboration using $2+1+1$-flavors of dynamical highly improved staggered quarks (HISQ). The correlation functions are calculated using the Wilson-Clover action and the renormalization of the three operators is carried out nonperturbatively on the lattice in the RI${}^prime$-MOM scheme. The data have been collected at lattice spacings $a approx 0.15, 0.12, 0.09,$ and 0.06 fm and $M_pi approx 310, 220$ and 135 MeV, which are used to obtain the physical values using a simultaneous chiral-continuum-finite-volume fit. The final results, in the $overline{MS}$ scheme at 2 GeV, are $langle x rangle_{u-d} = 0.173(14)(07)$, $langle x rangle_{Delta u-Delta d} = 0.213(15)(22)$ and $langle x rangle_{delta u-delta d} = 0.208(19)(24)$, where the first error is the overall analysis uncertainty and the second is an additional systematic uncertainty due to possible residual excited-state contributions. These results are consistent with other recent lattice calculations and phenomenological global fit values.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
