TY  - JOUR
AU  - Kleiss, R. H. P.
AU  - Malamos, I.
AU  - Papadopoulos, C. G.
AU  - Verheyen, R.
PY  - 2012
DA  - 2012//
TI  - Counting to one: reducibility of one- and two-loop amplitudes at the integrand level
T2  - J. High Energy Phys.
JO  - Journal of High Energy Physics
SP  - 038
EP  - 24pp
VL  - 12
IS  - 12
PB  - Springer
KW  - QCD Phenomenology
KW  - NLO Computations
AB  - Calculation of amplitudes in perturbative quantum field theory involve large loop integrals. The complexity of those integrals, in combination with the large number of Feynman diagrams, make the calculations very difficult. Reduction methods proved to be very helpful, lowering the number of integrals that need to be actually calculated. Especially reduction at the integrand level improves the speed and set-up of these calculations. In this article we demonstrate, by counting the numbers of tensor structures and independent coefficients, how to write such relations at the integrand level for one-and two-loop amplitudes. We clarify their connection to the so-called spurious terms at one loop and discuss their structure in the two-loop case. This method is also applicable to higher loops, and the results obtained apply to both planar and non-planar diagrams.
SN  - 1126-6708
UR  - http://arxiv.org/abs/1206.4180
UR  - https://doi.org/10.1007/JHEP12(2012)038
DO  - 10.1007/JHEP12(2012)038
LA  - English
N1  - WOS:000313123800038
ID  - Kleiss_etal2012
ER  -