Strangeness contribution to the proton spin from lattice QCD.
نویسندگان
چکیده
We compute the strangeness and light-quark contributions Δs, Δu, and Δd to the proton spin in n(f)=2 lattice QCD at a pion mass of about 285 MeV and at a lattice spacing a≈0.073 fm, using the nonperturbatively improved Sheikholeslami-Wohlert Wilson action. We carry out the renormalization of these matrix elements, which involves mixing between contributions from different quark flavors. Our main result is the small negative value Δs(MS)(√(7.4) GeV)=-0.020(10)(4) of the strangeness contribution to the nucleon spin. The second error is an estimate of the uncertainty, due to the missing extrapolation to the physical point.
منابع مشابه
A New Technique for Measuring the Strangeness Content of the Proton on the Lattice
A new technique for computing the strangeness content of the proton on the lattice is described. It is applied to the calculation of the strange quark contribution to the proton’s spin, specifically to the evaluation of the matrix element . Preliminary results are not in disagreement with the ps sγμγ5 s ps EMC experiment. 2 The EMC experiment measuring the structure function in polarized deep i...
متن کاملQuark Orbital Angular Momentum from Lattice QCD
employs the Z2 noise with an unbiased subtraction. This reduced the error by a factor of 4 with negligible overhead. The total quark contribution to the proton spin is found to be 0.30±0.07. From this and the quark spin content we deduce the quark orbital angular momentum to be 0.17 ± 0.06 which is ∼ 34% of the proton spin. We further predict that the gluon angular momentum to be 0.20 ± 0.07, i...
متن کاملapplication to the problem of the strangeness
The baryon octet magnetic moments to all orders in flavor breaking; an application to the problem of the strangeness in the nucleon Abstract. Using the general QCD parametrization (GP) we display the magnetic moments of the octet baryons including all flavor breaking terms to any order. The hierarchy of the GP parameters allows to estimate a parameter g 0 related to the quark loops contribution...
متن کاملar X iv : h ep - l at / 9 80 90 29 v 1 6 S ep 1 99 8 1 Lattice calculation of the strangeness and electromagnetic nucleon form factors
We report on recent lattice QCD calculations of the strangeness magnetic moment of the nucleon and the nucleon electromagnetic form factors, when we allow the electromagnetic current to connect to quark loops as well as to the valence quarks. Our result for the strangeness magnetic moment is G s M (0) = −0.36 ± 0.20. The sea contributions from the u and d quarks are about 80% larger. However, t...
متن کاملProton Spin Content From Lattice QCD
We calculate the form factor of the quark energy momentum tensor and thereby extract the quark orbital angular momentum of the nucleon. The calculation is done on a quenched 16 × 24 lattice at β = 6.0 and with Wilson fermions at κ = 0.148, 0.152, 0.154 and 0.155. We calculate the disconnected insertion stochastically which employs the Z2 noise with an unbiased subtraction. This proves to be an ...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Physical review letters
دوره 108 22 شماره
صفحات -
تاریخ انتشار 2012