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At small inter-parton distances, double parton distributions receive their dominant contribution from the splitting of a single parton. We compute this mechanism at next-to-leading order in perturbation theory for all colour configurations…

High Energy Physics - Phenomenology · Physics 2021-09-01 Markus Diehl , Jonathan R. Gaunt , Peter Ploessl

Starting from the general definition of a one-loop tensor N-point function, we use its Feynman parametrization to calculate the UV-divergent part of an arbitrary tensor coefficient in the framework of dimensional regularization. In contrast…

High Energy Physics - Phenomenology · Physics 2017-07-05 Georg Sulyok

Double parton distributions (DPDs) receive a short-distance contribution from a single parton splitting to yield the two observed partons. We investigate this mechanism at next-to-leading order (NLO) in perturbation theory. Technically, we…

High Energy Physics - Phenomenology · Physics 2019-08-07 Markus Diehl , Jonathan R. Gaunt , Peter Ploessl , Andreas Schafer

In higher order calculations a number of new technical problems arise: one needs diagrams in arbitrary dimension in order to obtain their needed $\epsilon$-expansion, zero Gram determinants appear, renormalization produces diagrams with…

High Energy Physics - Phenomenology · Physics 2009-11-07 J. Fleischer , O. V. Tarasov , T. Riemann , A. Werthenbach

Negative dimensional integration is a step further dimensional regularization ideas. In this approach, based on the principle of analytic continuation, Feynman integrals are polynomial ones and for this reason very simple to handle,…

High Energy Physics - Theory · Physics 2009-10-30 Alfredo T. Suzuki , Alexandre G. M. Schmidt

A general procedure for the calculation of a class of two-loop Feynman diagrams is described. These are two-point functions containing three massive propagators, raised to integer powers, in the denominator, and arbitrary polynomials of the…

High Energy Physics - Phenomenology · Physics 2015-06-25 P. Post , J. B. Tausk

We describe a constructive procedure to separate overlapping infrared divergences in multi-loop integrals. Working with a parametric representation in D=4-2*epsilon dimensions, adequate subtractions lead to a Laurent series in epsilon,…

High Energy Physics - Phenomenology · Physics 2009-10-31 T. Binoth , G. Heinrich

We consider UV divergences for the on-shell planar gluon-gluon scattering amplitudes in the gauge theory in arbitrary D-dimensions in the one-loop order. The amplitudes are evaluated using the standard Feynman diagram technique for several…

High Energy Physics - Theory · Physics 2022-04-27 A. T. Borlakov , D. I. Kazakov

An explicit Loop Tree Duality (LTD) formula for two-loop Feynman integrals with integer power of propagators is presented and used for a numerical UV divergence subtraction algorithm. This algorithm proceeds recursively and it is based on…

High Energy Physics - Phenomenology · Physics 2024-09-04 Daniele Artico

The paradigmatic model of the directed percolation process is studied near its second order phase transition between an absorbing and an active state. The model is first expressed in a form of Langevin equation and later rewritten into a…

Statistical Mechanics · Physics 2019-10-23 Š. Birnšteinová , M. Hnatič , T. Lučivjanský , L. Mižišin , V. Škultéty

We study quantum loop corrections to two-point functions and extraction of physical quantities in a five-dimensional $\phi^4$ theory on an orbifold. At two-loop level, we find that divergence for quartic derivative terms of $(p^2)^2$ appear…

High Energy Physics - Phenomenology · Physics 2009-12-04 Nobuhiro Uekusa

We discuss multivariate Monte Carlo methods appropriate for X-ray dispersive spectrometers. Dispersive spectrometers have many advantages for high resolution spectroscopy in the X-ray band. Analysis of data from these instruments is…

Astrophysics · Physics 2007-05-23 J. R. Peterson , J. G. Jernigan , S. M. Kahn

We examine the two-photon exchange corrections to elastic electron-proton scattering within a dispersive approach, including contributions from both Nucleon and Delta intermediate states. The dispersive analysis avoids off-shell…

Nuclear Theory · Physics 2017-06-21 P. G. Blunden , W. Melnitchouk

In this paper we present a novel technique based on deep reinforcement learning that allows for numerical analytic continuation of integrals that are often encountered in one-loop diagrams in quantum field theory. In order to extract…

High Energy Physics - Phenomenology · Physics 2020-03-25 Andreas Windisch , Thomas Gallien , Christopher Schwarzlmueller

We present new methods for the evaluation of one-loop tensor integrals which have been used in the calculation of the complete electroweak one-loop corrections to e+ e- -> 4 fermions. The described methods for 3-point and 4-point integrals…

High Energy Physics - Phenomenology · Physics 2008-11-26 A. Denner , S. Dittmaier

A comprehensive study is performed of two-loop Feynman diagrams with three external legs which, due to the exchange of massless gauge-bosons, give raise to infrared and collinear divergencies. Their relevance in assembling realistic…

High Energy Physics - Phenomenology · Physics 2009-11-11 Giampiero Passarino , Sandro Uccirati

The Standard Model prediction for $\mu$-$e$ scattering at Next-to-Next-to-Leading Order (NNLO) contains non-perturbative QCD contributions given by diagrams with a hadronic vacuum polarization insertion in the photon propagator. By taking…

High Energy Physics - Phenomenology · Physics 2019-02-20 Matteo Fael

A new approach is presented to evaluate multi-loop integrals, which appear in the calculation of cross-sections in high-energy physics. It relies on a fully numerical method and is applicable to a wide class of integrals with various mass…

High Energy Physics - Phenomenology · Physics 2015-06-03 F. Yuasa , E. de Doncker , N. Hamaguchi , T. Ishikawa , K. Kato , Y. Kurihara , J. Fujimoto , Y. Shimizu

We apply a diagrammatic Monte Carlo method to the problem of an impurity interacting resonantly with a homogeneous Fermi bath for a quasi-two-dimensional setup. Notwithstanding the series divergence, we can show numerically that the three…

Quantum Gases · Physics 2014-09-18 Peter Kroiss , Lode Pollet

Dispersion diagrams play a crucial role in examining, analyzing and designing wave propagation in periodic structures. Despite their ubiquity and current research interest, introductory papers and reference scripting tailored to novel…

Applied Physics · Physics 2024-04-19 Vanessa Cool , Elke Deckers , Lucas Van Belle , Claus Claeys