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Register a new userNonperturbative Corrections to One Gluon Exchange Quark Potentials
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The leading nonperturbative QCD corrections to the one gluon exchange quark-quark, quark-antiquark and $q bar{q}$ pair-excitation potentials are derived by using a covariant form of nonlocal two-quark and two-gluon vacuum expectation values. Our numerical calculation indicates that the correction of quark and gluon condensates to the quark-antiquark potential improves the heavy quarkonium spectra to some degree.
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We summarize recent results on the nonperturbative quark-gluon interaction in Landau gauge QCD. Our analytical analysis of the infrared behaviour of the quark-gluon vertex reveals infrared singularities, which lead to an infrared divergent running coupling and a linear rising quark-antiquark potential when chiral symmetry is broken. In the chirally symmetric case we find an infrared fixed point of the coupling and, correspondingly, a Coulomb potential. These findings provide a new link betwen dynamical chiral symmetry breaking and confinement.
We evaluate heavy-quark (HQ) transport properties in a Quark-Gluon Plasma (QGP) employing interaction potentials extracted from thermal lattice QCD. Within a Brueckner many-body scheme we calculate in-medium T-matrices for charm- and bottom-quark scattering off light quarks in the QGP. The interactions are dominated by attractive meson and diquark channels which support bound and resonance states up to temperatures of ~1.5 T_c. We apply pertinent drag and diffusion coefficients (supplemented by perturbative scattering off gluons) in Langevin simulations in an expanding fireball to compute HQ spectra and elliptic flow in sqrt{s_{NN}}=200 GeV Au-Au collisions. We find good agreement with semileptonic electron-decay spectra which supports our nonperturbative computation of the HQ diffusion coefficient, suggestive for a strongly coupled QGP.
A Higgs boson produced in association with one or more bottom quarks is of great theoretical and experimental interest to the high-energy community. A precise prediction of its total and differential cross-section can have a great impact on the discovery of a Higgs boson with large bottom-quark Yukawa coupling, like the scalar (h^0 and H^0) and pseudoscalar (A^0) Higgs bosons of the Minimal Supersymmetric Standard Model (MSSM) in the region of large tanbeta. In this paper we apply the threshold resummation formalism to determine both differential and total cross-sections for b g to bPhi (where Phi = h^0, H^0), including up to next-to-next-to-next-to-leading order (NNNLO) soft plus virtual QCD corrections at next-to-leading logarithmic (NLL) accuracy. We present results for both the Fermilab Tevatron and the CERN Large Hadron Collider (LHC).
We review free energy evolution of QGP (Quark-gluon plasma) under zero-loop, one loop and two loop corrections in the mean field potential. The free energies of QGP under the comparison of zero-loop and loop corrections of the interacting potential among the quarks, anti-quarks and gluons are shown. We observe that the formation of stable QGP droplet is dependent on the loop corrections with the different parametrization values of fluid. With the increase in the parametrization value, stability of droplet formation increases with smaller size of droplet. This indicates that the formation of QGP droplet can be signified more importantly by the parametrization value like the Reynold number in fluid dynamics. It means that there may be different phenomenological parameter to define the stable QGP droplet when QGP fluid is studied under loop corrections.
We provide a quantum field theory based description of the nonperturbative effects from hadronization for soft drop groomed jet mass distributions using the soft-collinear effective theory and the coherent branching formalism. There are two distinct regions of jet mass $m_J$ where grooming modifies hadronization effects. In a region with intermediate $m_J$ an operator expansion can be used, and the leading power corrections are given by three universal nonperturbative parameters that are independent of all kinematic variables and grooming parameters, and only depend on whether the parton initiating the jet is a quark or gluon. The leading power corrections in this region cannot be described by a standard normalized shape function. These power corrections depend on the kinematics of the subjet that stops soft drop through short distance coefficients, which encode a perturbatively calculable dependence on the jet transverse momentum, jet rapidity, and on the soft drop grooming parameters $z_{rm cut}$ and $beta$. Determining this dependence requires a resummation of large logarithms, which we carry out at LL order. For smaller $m_J$ there is a nonperturbative region described by a one-dimensional shape function that is unusual because it is not normalized to unity, and has a non-trivial dependence on $beta$.
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