Alexander Mitov

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We study the fragmentation of the b quark in top decay in NLO QCD, within the framework of perturbative fragmentation, which allows one to resum large logarithms ∼ log(m 2 t /m 2 b). We show the b-energy distribution, which we compare with the exact O(α S) result for a massive b quark. We use data from e + e − machines in order to describe the b-quark(More)
We study soft-gluon radiation in top quark decay within the framework of perturbative fragmentation functions. We present results for the b-quark energy distribution, accounting for soft-gluon resummation to next-to-leading logarithmic accuracy in both the MS coefficient function and in the initial condition of the per-turbative fragmentation function. The(More)
We present the two-loop virtual QCD corrections to the production of heavy quarks in the quark– anti-quark–annihilation channel in the limit when all kinematical invariants are large compared to the mass of the heavy quark. Our result is exact up to terms suppressed by powers of the heavy-quark mass. The derivation is based on a simple relation between(More)
We have investigated the next-to-next-to-leading order (NNLO) corrections to inclusive hadron production in e + e − annihilation and the related parton fragmentation distributions, the 'time-like' counterparts of the 'space-like' deep-inelastic structure functions and parton densities. We have re-derived the corresponding second-order coefficient functions(More)
We discuss the structure of infrared singularities in on-shell QCD amplitudes with massive partons and present a general factorization formula in the limit of small parton masses. The factorization formula gives rise to an all-order exponentiation of both, the soft poles in dimensional regular-ization and the large collinear logarithms of the parton masses.(More)
We determine the dominant missing standard model (SM) contribution to the top quark pair forward-backward asymmetry at the Tevatron. Contrary to past expectations, we find a large, around 27%, shift relative to the well-known value of the inclusive asymmetry in next-to-leading order QCD. Combining all known standard model corrections, we find that(More)