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We present a complete set of one-loop matrix elements relevant for the hadroproduction of heavy quarks in next-to-leading order employing dimensional regularization to isolate ultraviolet and soft divergences. All results of the…

High Energy Physics - Phenomenology · Physics 2014-11-17 J. G. Korner , Z. Merebashvili

We consider the singular behaviour of tree-level QCD amplitudes when the momenta of three partons become simultaneously parallel. We discuss the universal factorization formula that controls the singularities of the multiparton matrix…

High Energy Physics - Phenomenology · Physics 2009-10-31 S. Catani , M. Grazzini

This is the first in a series of papers, in which we compute the third-order QCD corrections to top-antitop production near threshold in e+ e- collisions. The present paper provides a detailed outline of the strategy of computation in the…

High Energy Physics - Phenomenology · Physics 2024-09-11 M. Beneke , Y. Kiyo , K. Schuller

Perturbative matching relates the parton quasi-distributions, defined by Euclidean correlators at finite hadron momenta, to the light-cone distributions which are accessible in experiments. Previous matching calculations have exclusively…

High Energy Physics - Phenomenology · Physics 2023-07-14 Shohini Bhattacharya , Krzysztof Cichy , Martha Constantinou , Andreas Metz , Aurora Scapellato , Fernanda Steffens

We study the electromagnetic on-shell form factor of quarks in massless perturbative QCD. We derive the complete pole part in dimensional regularization at three loops, and extend the resummation of the form factor to the…

High Energy Physics - Phenomenology · Physics 2009-11-11 S. Moch , J. A. M. Vermaseren , A. Vogt

We compute the imaginary part of the heavy quark contribution to the photon polarization tensor, i.e. the quarkonium spectral function in the vector channel, at next-to-leading order in thermal QCD. Matching our result, which is valid…

High Energy Physics - Phenomenology · Physics 2009-02-09 Y. Burnier , M. Laine , M. Vepsalainen

We present a complete description of the calculation of the spin-dependent next-to-leading order splitting functions. The calculation is performed in the light-cone gauge. We give results for different prescriptions for the Dirac matrix…

High Energy Physics - Phenomenology · Physics 2008-11-26 W. Vogelsang

We present the two-mass QCD contributions to the polarized pure singlet operator matrix element at three loop order in $x$-space. These terms are relevant for calculating the polarized structure function $g_1(x,Q^2)$ at $O(\alpha_s^3)$ as…

High Energy Physics - Phenomenology · Physics 2020-01-15 J. Ablinger , J. Blümlein , A. De Freitas , M. Saragnese , C. Schneider , K. Schönwald

We construct a resummation at partial next-to-next-to-next-to-leading logarithmic accuracy for hadronic top-quark pair production near partonic threshold, including simultaneously soft-gluon and Coulomb corrections, and use this result to…

High Energy Physics - Phenomenology · Physics 2018-08-29 Jan Piclum , Christian Schwinn

Using the Schr\"odinger functional we have computed a variety of renormalized on-shell correlation functions to one-loop order of perturbation theory. By studying their approach to the continuum limit we have determined the O($a$)…

High Energy Physics - Lattice · Physics 2009-10-30 Stefan Sint , Peter Weisz

We perform a next-to-next-to-leading order (NNLO) QCD analysis of the charm-top-quark contribution eta_ct to the effective Delta S = 2 Hamiltonian in the Standard Model. eta_ct represents an important part of the short distance contribution…

High Energy Physics - Phenomenology · Physics 2010-12-16 Joachim Brod , Martin Gorbahn

We compute the polarized splitting functions in the triple collinear limit at next-to-leading order accuracy (NLO) in the strong coupling $\alpha_{\rm S}$, for the splitting processes $\gamma \to q \bar{q} \gamma$, $\gamma \to q \bar{q} g$…

High Energy Physics - Phenomenology · Physics 2015-03-12 German F. R. Sborlini , Daniel de Florian , German Rodrigo

We present all relevant details of our calculation of the complete next-to-leading order (O(alpha_s^2 alpha)) QCD corrections to heavy flavor photoproduction with longitudinally polarized point-like photons and hadrons. In particular we…

High Energy Physics - Phenomenology · Physics 2011-01-25 I. Bojak , M. Stratmann

The short-distance coefficients for the color-octet ^3S_1 term in the fragmentation function for a gluon to split into polarized heavy quarkonium states are re-calculated to order alpha_s^2. The light-cone gauge remarkably simplifies the…

High Energy Physics - Phenomenology · Physics 2009-11-11 Jungil Lee

We calculate the third coefficient of the lattice beta function in QCD with Wilson fermions, extending the pure gauge results of Luescher and Weisz; we show how this coefficient modifies the scaling function on the lattice. We also…

High Energy Physics - Lattice · Physics 2009-10-30 B. Alles , C. Christou , A. Feo , H. Panagopoulos , E. Vicari

Starting from the Schr\"odinger functional, we give a non-perturbative definition of the running coupling constant in QCD. The spatial boundary conditions for the quark fields are chosen such that the massless Dirac operator in the…

High Energy Physics - Lattice · Physics 2009-10-28 Stefan Sint , Rainer Sommer

We present the one-loop matching condition for the unpolarized and polarized generalized quark distributions in the non-singlet case. The matching condition links the quasi distributions defined in terms of spacelike correlators at finite…

High Energy Physics - Phenomenology · Physics 2015-09-28 Xiangdong Ji , Andreas Schäfer , Xiaonu Xiong , Jian-Hui Zhang

In many calculations involving polarized twist-2 parton densities to higher order in the strong coupling constant one uses the Larin scheme to describe chiral effects in dimensional regularization. Upon forming observables, the scheme…

High Energy Physics - Phenomenology · Physics 2024-05-28 J. Blümlein , M. Saragnese

We present the first lattice QCD calculations of the isovector helicity transverse momentum-dependent parton distribution function (TMDPDF) and the flavor-dependent unpolarized TMDPDFs for up and down quarks in the proton. Our computations…

High Energy Physics - Lattice · Physics 2025-11-18 Dennis Bollweg , Xiang Gao , Swagato Mukherjee , Yong Zhao

We describe a procedure to determine moments of parton distribution functions of any order in lattice quantum chromodynamics (QCD). The procedure is based on the gradient flow for fermion and gauge fields. The flowed matrix elements of…

High Energy Physics - Lattice · Physics 2024-10-03 Andrea Shindler
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