Related papers: Steps towards NNLO QCD calculations: collinear fac…
To find boundary contributions is a rather difficult problem when applying the BCFW recursion relation. In this paper, we propose an approach to bypass this problem by calculating general tree amplitudes that contain no polynomial using…
We consider inclusive $\psi(2S)$ production in proton-proton collisions at collider energies in the framework of non-relativistic QCD and high-energy factorization beyond the low-order approximation. We utilise a matching scheme proposed…
We analyse the singular behaviour of one-loop integrals and scattering amplitudes in the framework of the loop--tree duality approach. We show that there is a partial cancellation of singularities at the loop integrand level among the…
We present a short overview on transverse momentum dependent parton distribution and fragmentation functions, giving their partonic interpretation and ways to access them. We then discuss the issue of their universality and its connection…
We present an overview of techniques developed in recent years for the efficient calculation of one-loop multiparton amplitudes, in particular those relying on unitarity and collinear factorization.
I compare collinear and $k_T$ factorization theorems in perturbative QCD, and discuss their application to exclusive $B$ meson decays. Especially, I concentrate on the recently measured time-dependent CP asymmetry of the…
We recompute the functions describing the collinear factorization of one-loop amplitudes using the unitarity-based method. We present the results in a form suitable for use as an ingredient in two-loop calculations. We also present a…
A variety of universal similarity factorization equalities over real Clifford algebras ${\cal R}_{p,q}$ are established. On the basis of these equalities, real, complex and quaternion matrix representations of elements in ${\cal R}_{p,q}$…
We develop the analysis of diphoton exclusive photoproduction in the kinematics where a collinear QCD factorization framework applies, namely nearly forward large invariant mass diphoton production. We work at the leading twist level and at…
In this talk we discuss an algorithm for the numerical calculation of one-loop QCD amplitudes and present results at next-to-leading order for jet observables in electron-positron annihilation calculated with the above-mentioned method. The…
We investigate the double logarithmic corrections $\alpha_s\ln^2 x$, x being a parton momentum fraction, in two-body nonleptonic B meson decays in collinear factorization theorem of perturbative QCD (PQCD). It is found that these…
We analyze in detail the most singular behaviour of processes involving triple-collinear splittings with massive particles in the quasi-collinear limit, and present compact expressions for the splitting amplitudes and the corresponding…
We formulate and prove a QCD factorization theorem for hard exclusive electroproduction of mesons in QCD. The proof is valid for the leading power in Q and all logarithms. This generalizes previous work on vector meson production in the…
Description of spin-dependent hadronic processes at high energies in terms of parton helicities is a both effective and technically convenient means. In the present paper, we obtain explicit expressions for the parton helicities when either…
We calculate the cross section for the inclusive production of single hadrons with finite transverse momenta in deep-inelastic scattering at next-to-leading order (NLO), i.e. through O(alpha_s^2), in the parton model of QCD endowed with…
The equation of gluodynamics with modified integral kernel is solved up to 2NLO (next-to-next-to-leading order) and 3NLO (next-to-next-to-next-to-leading order) in perturbative QCD. A relationship between the nuclear factor Ns and the ratio…
We employ the worldline formalism to derive a series representation of the low-energy limit of the N -photon amplitude in a constant background field for both scalar and spinor QED. The amplitudes are then written in terms of a single…
Factorization theorems play a crucial role in our understanding of the strong interaction. For collider processes they are typically formulated at leading power and much less is known about power corrections in the $\lambda\ll 1$ expansion.…
We calculate the cross section of a pion diffraction dissociation in two jets with large transverse momenta originating from a hard gluon exchange between the pion constituents. To the leading logarithmic accuracy (in energy), the…
We compute the four-quark plus three-gluon and six-quark plus one-gluon tree level amplitudes using on-shell recursion relations. They are needed for the calculation of the 5-jet cross-section at the Born level, and constitute an essential…