相关论文: Massless Parton Asymptotics within Variable Flavou…

Charm final states in deep inelastic scattering constitute $\sim 25%$ of the inclusive cross-section at small $x$ as measured at HERA. These data can reveal important information on the charm and gluon structure of the nucleon if they are…

Based on our recent NNLO dynamical parton distributions as obtained in the `fixed flavor number scheme', we generate radiatively parton distributions in the `variable flavor number scheme' where also the heavy quark flavors (c,b,t) become…

Reparameterization invariance, a symmetry of heavy quark effective theory, appears in different forms in the literature. The most commonly cited forms of the reparameterization transformation are shown to induce the same constraints on…

We have completed the ${\cal O}(\alpha_s)$ QCD corrections to exclusive heavy quark-antiquark distributions in deep inelastic electroproduction and present here the differential distributions in the masses of charm-anticharm and…

We calculate the massive Wilson coefficients for the heavy flavor contributions to the non-singlet charged current deep-inelastic scattering structure functions $F_L^{W^+}(x,Q^2)-F_L^{W^-}(x,Q^2)$ and $F_2^{W^+}(x,Q^2)-F_2^{W^-}(x,Q^2)$ in…

Recent theoretical and experimental improvements in the determination of charm and bottom quark masses are discussed. A new and improved evaluation of the contribution from the gluon condensate $< \frac{\alpha_s}{\pi} G^2>$ to the charm…

In this paper various theoretical approaches are used to define the dependence of the estimated $\mathcal{O}(\alpha^5_s)$ and $\mathcal{O}(\alpha^6_s)$-corrections to the QCD relation between pole and $\rm{\overline{MS}}$ running masses of…

We present a test of the flavour independence of the strong coupling constant for charm and bottom quarks with respect to light (uds) quarks, based on a hadronic event sample obtained with the OPAL detector at LEP. Five observables related…

The matching relations in the unpolarized and polarized variable flavor number scheme at three-loop order are presented in the single-mass case. They describe the process of massive quarks becoming light at large virtualities $Q^2$. In this…

We study the spectra of the bottomonium and B_c states within perturbative QCD up to order alpha_s^4. The O(Lambda_QCD) renormalon cancellation between the static potential and the pole mass is performed in the epsilon-expansion scheme. We…

We show how one can resum the large logarithms which occur in the charm component of the structure function F_{k,c}(x,Q^2,m_c^2) (k=2,L) taken at three light flavours, in the limit Q^2 \gg m_c^2. This resummation leads to an expression of…

An updated heavy quark-antiquark potential is constructed by matching the short-distance perturbative part to long-distance lattice QCD results at an intermediate r scale. The static potential and the order 1/m potential are both analyzed…

We report on recent results on the two-mass corrections for massive operator matrix elements at 2- and 3-loop orders in QCD. These corrections form the building blocks of the variable flavor number scheme. Due to the similar values of the…

The determination of quark masses from lattice QCD simulations requires a non-perturbative renormalization procedure and subsequent scale evolution to high energies, where a conversion to the commonly used MS-bar scheme can be safely…

Conventional perturbative QCD calculations on the production of a heavy quark ``$H$'' consist of two contrasting approaches: the usual QCD parton formalism uses the zero-mass approximation ($m_H=0$) once above threshold, and treats $H$ just…

We calculate the O($\eps$)--term of the two--loop massive operator matrix elements for twist 2--operators, which contribute to the heavy flavour Wilson coefficients in unpolarized deep--inelastic scattering in the asymptotic limit $Q^2 \gg…

We present new results for QCD corrections to the top-pair invariant mass and top-quark $p_T$ distributions in boosted top-quark pair production at hadron colliders. They are derived from a formalism which allows the joint resummation of…

We discuss the renormalization and factorization scale dependence of charm and bottom production both at fixed-target energies and at present and future colliders. We investigate whether distributions calculable at leading order can be…

We calculate the leading order in $\alpha_s$ QCD amplitude for exclusive neutrino and antineutrino production of a $D$ pseudoscalar charmed meson on an unpolarized nucleon. We work in the framework of the collinear QCD approach where…

I summarize results and performance of the dynamical theory of charmless hadronic B decays, based on QCD factorization in the heavy quark limit. On the theoretical side, a number of NNLO (alpha_s^2) amplitudes are now available, all showing…