scholarly journals The complex-mass scheme for perturbative calculations with unstable particles

2006 ◽  
Vol 160 ◽  
pp. 22-26 ◽  
Author(s):  
A. Denner ◽  
S. Dittmaier
Keyword(s):  
Perturbative Calculations ◽  
Unstable Particles ◽  
Complex Mass

scholarly journals Complex-Mass Definition and the Structure of Unstable Particle’s Propagator

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Vladimir Kuksa
Keyword(s):  
Spectral Function ◽  
Unstable Particle ◽  
Unstable Particles ◽  
Spinor Fields ◽  
Complex Mass ◽  
Special Case ◽  
Mass Definition

The propagators of unstable particles are considered in framework of the convolution representation. Spectral function is found for a special case when the propagator of scalar unstable particle has Breit-Wigner form. The expressions for the dressed propagators of unstable vector and spinor fields are derived in an analytical way for this case. We obtain the propagators in modified Breit-Wigner forms which correspond to the complex-mass definition.

scholarly journals OpenLoops 2

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Federico Buccioni ◽  
Jean-Nicolas Lang ◽  
Jonas M. Lindert ◽  
Philipp Maierhöfer ◽  
Stefano Pozzorini ◽  
...  
Keyword(s):  
Scattering Amplitudes ◽  
Open Loop ◽  
The Other ◽  
Automated System ◽  
Special Treatment ◽  
Reduction Algorithm ◽  
Original Algorithm ◽  
Unstable Particles ◽  
Complex Mass ◽  
Gram Determinant

Abstract We present the new version of OpenLoops, an automated generator of tree and one-loop scattering amplitudes based on the open-loop recursion. One main novelty of OpenLoops 2 is the extension of the original algorithm from NLO QCD to the full Standard Model, including electroweak (EW) corrections from gauge, Higgs and Yukawa interactions. In this context, among several new features, we discuss the systematic bookkeeping of QCD–EW interferences, a flexible implementation of the complex-mass scheme for processes with on-shell and off-shell unstable particles, a special treatment of on-shell and off-shell external photons, and efficient scale variations. The other main novelty is the implementation of the recently proposed on-the-fly reduction algorithm, which supersedes the usage of external reduction libraries for the calculation of tree–loop interferences. This new algorithm is equipped with an automated system that avoids Gram-determinant instabilities through analytic methods in combination with a new hybrid-precision approach based on a highly targeted usage of quadruple precision with minimal CPU overhead. The resulting significant speed and stability improvements are especially relevant for challenging NLO multi-leg calculations and for NNLO applications.

scholarly journals Resummed corrections to the ρ parameter in the complex mass scheme

2011 ◽  
Vol 697 (1) ◽  
pp. 15-20 ◽  
Author(s):  
D. Bettinelli ◽  
J.J. van der Bij
Keyword(s):  
Complex Mass

Unstable Particles from Penetrating Showers

1953 ◽  
Vol 90 (2) ◽  
pp. 320-320 ◽  
Author(s):  
W. D. Walker ◽  
N. M. Duller
Keyword(s):  
Unstable Particles

scholarly journals COMPUTER PROGRAMS FOR ANALYTICAL PERTURBATIVE CALCULATIONS IN HIGH ENERGY PHYSICS

1994 ◽  
Vol 05 (06) ◽  
pp. 1089-1101 ◽  
Author(s):  
LEVAN R. SURGULADZE
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
High Energy Physics ◽  
Short Review ◽  
High Energy ◽  
Quantum Field ◽  
Perturbative Calculations ◽  
Mathematical Algorithm ◽  
Recent Computer ◽  
Energy Physics

A short review of the present status of computer packages for the high order analytical perturbative calculations is presented. The mathematical algorithm and the quantum field theory methods used are briefly discussed. The most recent computer package HEPLoops for analytical computations in high energy physics up to four-loops is also discussed.

Wave Equations for Unstable Particles

1970 ◽  
Vol 11 (7) ◽  
pp. 2222-2224
Author(s):  
Mayer Humi
Keyword(s):  
Wave Equations ◽  
Unstable Particles
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