Related papers: Treatment of heavy quarks in QCD

We present a next-to-next-to-leading order (NNLO) realization of a general quark mass scheme (S-ACOT-$\chi$) in deep inelastic scattering and explore the impact of NNLO terms on heavy-quark structure functions $F_{2,L}^{c}(x,Q)$. An amended…

Numerical solution of DGLAP $Q^2$ evolution equations is studied for polarized parton distributions by using a ``brute-force" method. NLO contributions to splitting functions are recently calculated,and they are included in our analysis.…

In a consistently formulated pQCD framework incorporating non-zero mass heavy quark partons, there is still the freedom to define parton distributions obeying either mass-independent or mass-dependent evolution equations, contrary to…

Using methods of effective field theory, a systematic analysis of the fragmentation functions D_{a/H}(x,m_Q) of a hadron H containing a heavy quark Q is performed (with a=Q,Q_bar,q,q_bar,g). By integrating out pair production of virtual and…

We derive the initial condition for the perturbative fragmentation function of a heavy quark through order O(alpha_s^2) in the MS-bar scheme. This initial condition is useful for computing heavy quark (or lepton, in case of QED) energy…

We introduce the physical factorisation scheme, which is necessary to describe observables which are `not completely inclusive'. We derive the formulae for NLO DGLAP evolution in this scheme, and also for the `rotation' of the conventional…

We describe the impact on PDF extractions of the 'Physical Scheme', a heavy-quark mass scheme that accounts for the effects of intrinsic heavy-quarks and provides a way to smoothly transition over the heavy-quark thresholds. The…

We derive the gluon initiated contribution to the initial condition for the perturbative fragmentation function of a heavy quark through order O(\alpha_s^2) in the MS-bar scheme. This result is needed for the resummation with…

I present a method for calculating heavy quark production which extrapolates smoothly from the well understood limits of the fixed-flavour number scheme for Q^2 approx m_H^2 to the zero-mass scheme at Q^2/m_H^2 -> infinity. For all Q^2 >…

We consider the resummation of soft-gluon effects in heavy quark to heavy quark decays, namely the processes Q1 -> Q2 + (non QCD partons), where Q1 and Q2 are two different heavy quarks. We construct a new factorization scheme for threshold…

We take a look at how the differential distributions for top-quark production are affected by changing to the running mass scheme. Specifically we consider the transverse momentum, rapidity and pair-invariant mass distributions at NLO for…

We investigate the heavy quark mass effects on the parton distribution functions in the unpolarized virtual photon up to the next-to-leading order in QCD. Our formalism is based on the QCD-improved parton model described by the DGLAP…

Details of a recent calculation of O(alpha_s^2) corrections to the decay b -> c,l,nu_l, taking into account the c-quark mass, are described. Construction of the expansion in the mass ratio m_c/m_b as well as the evaluation of new four-loop…

We consider top-quark pair production at the LHC within the MSbar scheme for the renormalisation of the top-quark mass, and we present predictions for total and differential cross sections at next-to-next-to-leading order (NNLO) in QCD. Our…

We present an analytical calculation of the two-loop QCD corrections to the electromagnetic form factor of heavy quarks. The two-loop contributions to the form factor are reduced to linear combinations of master integrals, which are…

A formula for an improved spin--dependent potential between a heavy quark and a heavy antiquark was developed using Heavy Quark Effective Theory techniques. The leading logarithmic quark mass terms emerging from loop contributions were…

With the increasing experimental precision available at colliders, higher-order perturbative calculations are required to reduce the theory uncertainty in order to extract crucial QCD parameters, such as the strong coupling constant, to the…

We analyze the properties of the ACOT scheme for heavy quark production and make use of the MS-Bar massless results at NNLO and N3LO for the structure functions F2 and FL in neutral current deep-inelastic scattering to estimate the higher…

Processes involving heavy quarks in associated production, are usually described in two factorisation schemes: one in which the heavy quark is treated as an infinitely massive object, decoupled from QCD evolution, and one in which it is…

We define a general scheme for the evolution of fragmentation functions which resums both soft gluon logarithms and mass singularities in a consistent manner and to any order, and requires no additional theoretical assumptions. Using the…