ترغب بنشر مسار تعليمي؟ اضغط هنا

Three-gluon running coupling from lattice QCD at $N_f=2+1+1$: a consistency check of the OPE approach

33   0   0.0 ( 0 )
 نشر من قبل Jose Rodriguez-Quintero
 تاريخ النشر 2013
  مجال البحث
والبحث باللغة English




اسأل ChatGPT حول البحث

We present a lattice calculation of the renormalized running coupling constant in symmetric (MOM) and asymmetric ($widetilde{rm MOM}$) momentum substraction schemes including $u$, $d$, $s$ and $c$ quarks in the sea. An Operator Product Expansion dominated by the dimension-two $langle A^2rangle$ condensate is used to fit the running of the coupling. We argue that the agreement in the predicted $langle A^2rangle$ condensate for both schemes is a strong support for the validity of the OPE approach and the effect of this non-gauge invariant condensate over the running of the strong coupling.

قيم البحث

اقرأ أيضاً

We present results for the topological susceptibility at nonzero temperature obtained from lattice QCD with four dynamical quark flavours. We apply different smoothing methods, including gradient Wilson flow and over--improved cooling, before calcula ting the susceptibility. It is shown that the considered smoothing techniques basically agree among each other, and that there are simple scaling relations between flow time and the number of cooling/smearing steps. The topological susceptibility exhibits a surprisingly slow decrease at high temperature.
We compute various (generalized) isovector charges of the octet baryons. These include $g_A$, $g_T$ and $g_S$ as well as the unpolarized, polarized and transversity parton distribution function (PDF) momentum fractions $langle xrangle_{u^+-d^+}$, $la ngle xrangle_{Delta u^--Delta d^-}$ and $langle xrangle_{delta u^+-delta ^+}$. The simulations are carried out on a subset of the (isospin symmetric) $N_f=2+1$ flavour Coordinated Lattice Simulations (CLS) gauge ensembles with lattice spacings ranging from $aapprox 0.086,$fm down to $aapprox 0.050,$fm. First results on the breaking of flavour symmetry and the low energy constants $F$ and $D$ are presented. While SU(3) flavour symmetry violations are found to be sizeable for $g_A=langle 1rangle_{Delta u^+-Delta d^+}$, these are quite small for $g_T=langle 1rangle_{delta u^--delta d^-}$ and $langle xrangle_{u^+-d^+}$.
I report on the first application of a novel, generalized Bayesian reconstruction (BR) method for spectral functions to the characterization of QCD constituents. These spectral functions find applications in off-shell kinetics of the quark-gluon plas ma and in calculations of transport coefficients. The new BR method is applied to Euclidean propagator data, obtained in Landau gauge on lattices with $N_f=2+1+1$ dynamical flavors by the twisted mass at finite temperature (tmfT) collaboration. The deployed reconstruction method is designed for spectral functions that can exhibit positivity violation (opposed to that of hadronic bound states). The transversal and longitudinal gluon spectral functions show a robust structure composed of quasiparticle peak and a negative trough. Characteristic differences between the hadronic and the plasma phase and between the two channels become visible. We obtain the temperature dependence of the transversal and longitudinal gluon masses.
We present an investigation of the Rho-meson from Nf=2+1+1 flavour lattice QCD. The calculation is performed based on gauge configuration ensembles produced by the ETM collaboration with three lattice spacing values and pion masses ranging from 230 M eV to 500 MeV. Applying the Luscher method phase shift curves are determined for all ensembles separately. Assuming a Breit-Wigner form, the Rho-meson mass and width are determined by a fit to these phase shift curves. Mass and width combined are then extrapolated to the chiral limit, while lattice artefacts are not detectable within our statistical uncertainties. For the Rho-meson mass extrapolated to the physical point we find good agreement with experiment. The corresponding decay width differs by about two standard deviations from the experimental value.
We present results for the interaction of two kaons at maximal isospin. The calculation is based on 2+1+1 flavour gauge configurations generated by the ETM Collaboration (ETMC) featuring pion masses ranging from about 230 MeV to 450 MeV at three valu es of the lattice spacing. The elastic scattering length $a_0^{I=1}$ is calculated at several values of the bare strange quark and light quark masses. We find $M_K a_0 =-0.397(11)(_{-8}^{+0})$ as the result of a chiral and continuum extrapolation to the physical point. This number is compared to other lattice results.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا