Anomalous Threshold as the Pivot of Feynman Amplitudes

Goria, S.; Passarino, Giampiero

doi:10.1016/j.nuclphysbps.2008.09.124

Cited by 4 publications

(2 citation statements)

References 20 publications

(19 reference statements)

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“…From the mathematical viewpoint, the introduction of a width helps to protect the cross section from several singularities, called Landau singularities [1,2,3,4,5,6]. Let us explain this in a simple way.…”

Section: Introductionmentioning

confidence: 99%

D0C: A code to calculate scalar one-loop four-point integrals with complex masses

Nhung

Ninh

2009

Computer Physics Communications

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We present a new Fortran code to calculate the scalar one-loop four-point integral with complex internal masses, based on the method of 't Hooft and Veltman. The code is applicable when the external momenta fulfill a certain physical condition. In particular it holds if one of the external momenta or a sum of them is timelike or lightlike and therefore covers all physical processes at colliders. All the special cases related to massless external particles are treated separately. Some technical issues related to numerical evaluation and Landau singularities are discussed.

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Section: Introductionmentioning

confidence: 99%

D0C: A code to calculate scalar one-loop four-point integrals with complex masses

Nhung

Ninh

2009

Computer Physics Communications

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“…The singular IR behavior of QCD amplitudes is well-known through general factorization formulas [1,2]. The physical consequences of the emergence of unitarity thresholds [3,4], anomalous thresholds and more generally Landau singularities [4][5][6][7][8][9][10][11][12][13][14][15], for specific kinematical configurations, have also been extensively discussed in the literature. Indeed a thorough knowledge of the singular structure of scattering amplitudes is a prerequisite for obtaining theoretical predictions of physical observables.…”

Section: Introductionmentioning

confidence: 99%

Causality, unitarity thresholds, anomalous thresholds and infrared singularities from the loop-tree duality at higher orders

Aguilera-Verdugo

Driencourt-Mangin

Plenter

et al. 2019

J. High Energ. Phys.

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We present the first comprehensive analysis of the unitarity thresholds and anomalous thresholds of scattering amplitudes at two loops and beyond based on the loop-tree duality, and show how non-causal unphysical thresholds are locally cancelled in an efficient way when the forest of all the dual on-shell cuts is considered as one. We also prove that soft and collinear singularities at two loops and beyond are restricted to a compact region of the loop three-momenta, which is a necessary condition for implementing a local cancellation of loop infrared singularities with the ones appearing in real emission; without relying on a subtraction formalism.

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Golem95C: A library for one-loop integrals with complex masses

Cullen¹,

Guillet²,

Heinrich³

et al. 2011

Computer Physics Communications

104

126

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We present a program for the numerical evaluation of scalar integrals and tensor form factors entering the calculation of one-loop amplitudes which supports the use of complex masses in the loop integrals. The program is built on an earlier version of the golem95 library, which performs the reduction to a certain set of basis integrals using a formalism where inverse Gram determinants can be avoided. It can be used to calculate one-loop amplitudes with arbitrary masses in an algebraic approach as well as in the context of a unitarity-inspired numerical reconstruction of the integrand.Comment: 22 pages, 3 figure

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Anomalous Threshold as the Pivot of Feynman Amplitudes

Abstract: Reduction techniques, Landau singularities and differential equations for Feynman amplitudes are briefly reviewed.Comment: Contribution to the Proceedings of the 9th DESY workshop on "Loops and Legs in Quantum Field Theory", Sondershausen, April 2008. 6 pages latex

Cited by 4 publications

References 20 publications

D0C: A code to calculate scalar one-loop four-point integrals with complex masses

D0C: A code to calculate scalar one-loop four-point integrals with complex masses

Causality, unitarity thresholds, anomalous thresholds and infrared singularities from the loop-tree duality at higher orders

Golem95C: A library for one-loop integrals with complex masses

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