Article
Physics, Particles & Fields
Stefano Frixione, Bryan R. Webber
Summary: This article discusses how color flows can simplify the computation of matrix elements and enable parton shower Monte Carlos to achieve accuracy beyond leading color. By systematically employing these color flows, tree-level matrix elements and their soft limits can be given in a closed form that does not require any color algebra. Additionally, the study examines how color loops and dipole graphs can help extend the accuracy of Monte Carlos by including subleading-color effects.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
Joshua Davies, Kay Schoenwald, Matthias Steinhauser
Summary: We study the light-fermion three-loop corrections to gg -> HH using forward scattering kinematics in the limit of a vanishing Higgs boson mass, which covers a large part of the physical phase space. We compute the form factors and discuss the technical challenges. The approach outlined in this letter can be used to obtain the full virtual corrections to gg -> HH at next-to-next-to-leading order.
Article
Physics, Particles & Fields
Daniel de Florian, Ignacio Fabre, Gudrun Heinrich, Javier Mazzitelli, Ludovic Scyboz
Summary: This study combines NLO predictions with full top-quark mass dependence with approximate NNLO predictions for Higgs-boson pair production in gluon fusion. It examines the impact of anomalous couplings on various observables and provides numerical coefficients for the approximate NNLO cross section as a function of the anomalous couplings at root s = 14TeV.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Dhimiter D. Canko, Costas G. Papadopoulos, Nikolaos Syrrakos
Summary: Analytic expressions for three families of planar two-loop five-point Master Integrals with one off-shell leg are presented in terms of polylogarithmic functions, using the Simplified Differential Equations approach. The results are relevant for studying various 2 -> 3 scattering processes at the LHC, particularly for leading-color W + 2 jets production.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Bakul Agarwal, Stephen P. Jones, Andreas von Manteuffel
Summary: This study calculates the two-loop QCD corrections to gg -> ZZ involving a closed top-quark loop using a new method, with the amplitude expressed in terms of finite integrals derived by employing syzygies. Numerical integration results show agreement with previous expansions in asymptotic limits and provide ab initio results for intermediate partonic energies and non-central scattering at higher energies.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Luca Buonocore, Paolo Nason, Francesco Tramontano, Giulia Zanderighi
Summary: This study examines several basic photon and lepton-initiated processes at the LHC, utilizing recently developed photon and lepton parton densities for computation. The comparison of different calculation methods and their application in searching for exotic particles and observing Standard-Model processes are discussed.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Matthias Heller, Andreas von Manteuffel, Robert M. Schabinger, Hubert Spiesberger
Summary: The study focuses on the qq-initiated two-loop electroweak-QCD Drell-Yan scattering amplitude with vanishing light quark and lepton masses using dimensional regularization schemes. It is found that the infrared pole terms of the mixed two-loop amplitude are controlled by a known generalization of the dipole formula, and that exactly the same two-loop polarized hard scattering functions are obtained in both the standard 't Hooft-Veltman-Breitenlohner-Maison gamma(5) scheme and Kreimer's anticommuting gamma(5) scheme.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Astronomy & Astrophysics
Ansgar Denner, Giovanni Pelliccioli
Summary: This study focuses on the polarization of weak bosons in WZ production at the LHC, using the double-pole approximation and amplitude-level polarization separation. Results are compared between defining the polarization vectors in two different frames, presenting integrated and differential cross-sections in a realistic fiducial region.
Article
Physics, Particles & Fields
Fabrizio Caola, Silvia Ferrario Ravasio, Giovanni Limatola, Kirill Melnikov, Paolo Nason
Summary: In this study, we investigate the impact of linear power corrections related to QCD on certain collider observables. By presenting arguments, we conclude that such corrections do not appear in inclusive observables with respect to QCD radiation. Although our study is conducted in a simplified framework, the results can be applied, to some extent, to processes in both lepton and hadron colliders.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Simone Alioli, Alessandro Broggio, Matthew A. Lim
Summary: We study the resummation of the 0-jettiness resolution variable tau(0) for the top-quark pair production process in hadronic collisions. Starting from an effective theory framework, we derive a factorisation formula for this observable and calculate its corrections. By matching with fixed order calculations, we obtain the most accurate prediction for the process.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
Article
Physics, Particles & Fields
Jeffrey R. Forshaw, Jack Holguin
Summary: In QCD, coherence violation is an interesting and counter-intuitive phenomenon, almost all observables sensitive to soft radiation at hadron colliders will violate coherence to some degree.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Anatoly Radyushkin, Shuai Zhao
Summary: This study presents one-loop corrections for the newly introduced gluon condensate PDF F(x) and provides the expression for the gg-part of its evolution kernel. By strictly adhering to gauge invariance requirements and utilizing on-shell states, it was discovered that there were terms such as q^2δ(x) found for the ξ = 0 GPD F(x, q^2) at nonzero momentum transfer q. The results did not align with the original attempt of one-loop calculations for gluon states, indicating caution for calculations using matrix elements with virtual external gluons.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Daniele Lombardi, Marius Wiesemann, Giulia Zanderighi
Summary: This study computes the NNLO+PS predictions for W+W- production in hadronic collisions, matching them consistently with parton showers using the MINNLOPS method. By including spin correlations, interferences, and off-shell effects, the evaluation time of the two-loop contribution has been significantly reduced. The results show good agreement with experimental measurements from ATLAS and CMS, highlighting the importance of NNLO corrections and matching to parton showers for an accurate simulation of W+W- events.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
Martin Beneke, Philipp Boer, Jan-Niklas Toelstede, K. Keri Vos
Summary: This paper discusses the generalization of the leading-twist light-cone distribution amplitude for light mesons including QED effects and its renormalization group evolution at the strong-interaction scale Lambda(QCD). For charged mesons, there are qualitative differences in scale evolution between QCD and QED-generalized, especially regarding the endpoint behavior. The evolution equation is analytically solved to first order in the electromagnetic coupling alpha(em), which resums large logarithms in QCD while providing numerical estimates for QED corrections to Gegenbauer coefficients and inverse moments relevant to (QED-generalized) factorization theorems for hard exclusive processes.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Physics, Particles & Fields
C. A. Flett, J. A. Gracey, S. P. Jones, T. Teubner
Summary: We calculate the exclusive electroproduction, gamma*p -> Vp, of heavy quarkonia V to NLO in the collinear factorisation scheme, which has been formally proven for this process, extending the photoproduction phase space of the exclusive heavy quarkonia observable to electroproduction kinematics with an off-shell virtuality Q(2) carried by the photon. This process is relevant for diffractive scattering at HERA and the upcoming EIC, as well as at the proposed LHeC and FCC.
JOURNAL OF HIGH ENERGY PHYSICS
(2021)
Article
Optics
P. A. Krachkov, R. N. Lee, A. I. Milstein
Article
Astronomy & Astrophysics
P. A. Krachkov, R. N. Lee, A. I. Milstein
Article
Physics, Particles & Fields
Roman N. Lee
JOURNAL OF HIGH ENERGY PHYSICS
(2015)
Article
Astronomy & Astrophysics
R. N. Lee, A. I. Milstein
Article
Physics, Particles & Fields
Mikhail G. Kozlov, Roman N. Lee
JOURNAL OF HIGH ENERGY PHYSICS
(2016)
Article
Optics
P. A. Krachkov, R. N. Lee, A. I. Milstein
Article
Astronomy & Astrophysics
E. J. Downie, R. N. Lee, A. I. Milstein, G. Ron
Article
Computer Science, Interdisciplinary Applications
Roman N. Lee
Summary: Libra is a new package for Mathematica system that provides tools for transformation of first-order linear differential systems, reducing them to Fuchsian form, E-form, and providing formal solutions in terms of Goncharov's polylogarithms and generalized power series.
COMPUTER PHYSICS COMMUNICATIONS
(2021)
Article
Astronomy & Astrophysics
Fedor Ignatov, Roman N. Lee
Summary: This article investigates the charge asymmetry in the differential cross section of the process e(+)e(-) -> pi(+)pi(-) and finds significant deviations between experimental data and existing theoretical calculations. Through revisiting the contribution of two photon exchange diagrams and improving the description of the pion internal structure, the authors propose a natural and simple approach that shows remarkable consistency with experimental data.
Article
Astronomy & Astrophysics
P. A. Krachkov, R. N. Lee, A. I. Milstein
Summary: This study focuses on the electron-positron pair production by a photon in Coulomb field near the threshold. The analytical results for the energy spectrum and angular distribution of particles are obtained using the parameter Ze(2)/h over line v. It is demonstrated that the Furry-Sommerfeld-Maue approximation used in the previous study leads to incorrect results.
Article
Astronomy & Astrophysics
Amlan Chakraborty, Tobias Huber, Roman N. Lee, Andreas von Manteuffel, Robert M. Schabinger, Alexander V. Smirnov, Vladimir A. Smirnov, Matthias Steinhauser
Summary: We calculate the four-loop corrections to the Higgs-bottom vertex in massless QCD and provide analytic results for all color structures. The infrared poles of the renormalized form factor match the predicted four-loop pattern. Additionally, we utilize the results of the form factors for Higgs-bottom, photon-quark, and Higgs-gluon to determine hard matching coefficients in soft-collinear effective theory up to four-loop accuracy.
Article
Astronomy & Astrophysics
Roman N. Lee, Andreas von Manteuffel, Robert M. Schabinger, Alexander Smirnov, Vladimir A. Smirnov, Matthias Steinhauser
Summary: This study analytically computed all four-loop QCD corrections to the photon-quark and Higgs-gluon form factors involving a closed massless fermion loop. It also confirmed a previous conjecture for the analytical form of the nonfermionic contributions to the collinear anomalous dimensions of quarks and gluons through the calculation of nonplanar vertex integrals.
Article
Physics, Particles & Fields
Roman N. Lee
Proceedings Paper
Computer Science, Theory & Methods
Roman N. Lee
15TH INTERNATIONAL WORKSHOP ON ADVANCED COMPUTING AND ANALYSIS TECHNIQUES IN PHYSICS RESEARCH (ACAT2013)
(2014)
Article
Physics, Particles & Fields
Roman Lee, Peter Marquard, Alexander V. Smirnov, Vladimir A. Smirnov, Matthias Steinhauser
JOURNAL OF HIGH ENERGY PHYSICS
(2013)