scholarly journals Noncancellation of infrared singularities in collisions of massive quarks

2021 ◽  
Vol 103 (5) ◽  
Author(s):  
Fabrizio Caola ◽  
Kirill Melnikov ◽  
Davide Napoletano ◽  
Lorenzo Tancredi
Keyword(s):  
Infrared Singularities

scholarly journals A prescription for projectors to compute helicity amplitudes in D dimensions

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Long Chen
Keyword(s):  
Dimensional Regularization ◽  
Tensor Decomposition ◽  
Regularization Scheme ◽  
Lorentz Index ◽  
Dimensional Splitting ◽  
Lorentz Tensor ◽  
Helicity Amplitudes ◽  
Amplitude Level ◽  
Infrared Singularities

AbstractThis article discusses a prescription to compute polarized dimensionally regularized amplitudes, providing a recipe for constructing simple and general polarized amplitude projectors in D dimensions that avoids conventional Lorentz tensor decomposition and avoids also dimensional splitting. Because of the latter, commutation between Lorentz index contraction and loop integration is preserved within this prescription, which entails certain technical advantages. The usage of these D-dimensional polarized amplitude projectors results in helicity amplitudes that can be expressed solely in terms of external momenta, but different from those defined in the existing dimensional regularization schemes. Furthermore, we argue that despite being different from the conventional dimensional regularization scheme (CDR), owing to the amplitude-level factorization of ultraviolet and infrared singularities, our prescription can be used, within an infrared subtraction framework, in a hybrid way without re-calculating the (process-independent) integrated subtraction coefficients, many of which are available in CDR. This hybrid CDR-compatible prescription is shown to be unitary. We include two examples to demonstrate this explicitly and also to illustrate its usage in practice.

On infrared singularities

1997 ◽  
pp. 117-123
Author(s):  
Takahiro Kawai ◽  
Henry P. Stapp
Keyword(s):  
Infrared Singularities

scholarly journals DIFFICULTIES OF AN INFRARED EXTENSION OF DIFFERENTIAL RENORMALIZATION

1994 ◽  
Vol 09 (07) ◽  
pp. 1067-1096 ◽  
Author(s):  
L. V. AVDEEV ◽  
D. I. KAZAKOV ◽  
I. N. KONDRASHUK
Keyword(s):  
Perturbation Theory ◽  
Fourier Transformation ◽  
Two Dimensions ◽  
Test Scheme ◽  
Two Dimensional ◽  
Differential Identities ◽  
Feynman Integrals ◽  
Differential Renormalization ◽  
Self Consistent ◽  
Infrared Singularities

We investigate the possibility of generalizing the differential renormalization of D. Z. Freedman, K. Johnson and J. I. Latorre in an invariant fashion to theories with infrared divergencies via an infrared [Formula: see text] operation. Two-dimensional σ models and the four-dimensional ɸ4-theory diagrams with exceptional momenta are used as examples, while dimensional renormalization serves as a test scheme for comparison. We write the basic differential identities of the method simultaneously in co-ordinate and momentum space, introducing two scales which remove ultraviolet and infrared singularities. A consistent set of Fourier-transformation formulae is derived. However, the values for tadpole-type Feynman integrals in higher orders of perturbation theory prove to be ambiguous, depending on the order of evaluation of the subgraphs. In two dimensions, even earlier than this ambiguity manifests itself, renormalization-group calculations based on the infrared extension of differential renormalization lead to incorrect results. We conclude that the procedure of extended differential renormalization does not perform the infrared [Formula: see text] operation in a self-consistent way.

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

2019 ◽  
Vol 2019 (12) ◽  
Author(s):  
J. Jesús Aguilera-Verdugo ◽  
Félix Driencourt-Mangin ◽  
Judith Plenter ◽  
Selomit Ramírez-Uribe ◽  
Germán Rodrigo ◽  
...  
Keyword(s):  
Infrared Singularities
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