A scheme for systematically achieving accurate numerical evaluation of multi-loop Feynman diagrams is developed. This shows the feasibility of a project aimed to produce a complete calculation for two-loop predictions in the Standard Model. As a first step an algorithm, proposed by F. V. Tkachov and based on the so-called generalized Bernstein functional relation, is applied to one-loop multi-l...

The Standard-Model Higgs boson with mass MH ≫ 2MZ decays almost exclusively to pairs of W and Z bosons. We calculate the dominant two-loop corrections, of O(GFM 4 H), to the partial widths of these decays. In the on-mass-shell renormalization scheme, the correction factor is found to be 1 + 14.6%(MH/TeV) 2 + 16.9%(MH/TeV) 4, where the second term is the one-loop correction. We give full analyti...

It has been argued in the past that in baryogenesis via out-of-equilibrium decays one must consider loop diagrams that contain more than one baryon number violating coupling. In this note we argue that the requirement with regard to baryon number violating couplings in loop diagrams is that the interaction between the intermediate on-shell particles and the final particles should correspond to ...

Freddy Cachazo, ∗ Marcus Spradlin, 3, † and Anastasia Volovich ‡ Perimeter Institute for Theoretical Physics, Waterloo, Ontario N2J 2W9, Canada Institute for Advanced Study, Princeton NJ 08540, USA Michigan Center for Theoretical Physics, Ann Arbor MI 48104, USA Abstract We find an unexpected iterative structure within the two-loop five-gluon amplitude in N = 4 supersymmetric Yang-Mills theory....

For certain dimensionally-regulated massive twoand three-loop propagator-type diagrams the higher order ε-expansion is constructed.

We present the ultraviolet poles and finite terms of two-loop vertex corrections for diagrams with massive partons in the eikonal approximation. We discover and prove that the results for a set of the corrections generalize to n-loop eikonal diagrams. These results will enhance theoretical understanding and allow greater calculational accuracy for the many partonic processes where the eikonal a...

Due to a peculiar behavior at the open string midpoint, loop diagrams in Schnabl gauge were expected to fail to produce the relevant closed string moduli. We find that closed string moduli are generated because the Riemann surfaces are built with slanted wedges: semi-infinite strips whose edges have parameterizations related by scaling. We examine in detail one-loop string diagrams and find tha...

Motivated by the precision results in the electroweak theory studies of two-loop Feynman diagrams are performed. Specifically this paper gives a contribution to the knowledge of massive two-loop selfenergy diagrams in arbitrary and especially four dimensions. This is done in three respects: firstly results in terms of generalized, multivariable hypergeometric functions are presented giving expl...

Massive 3-loop Feynman diagrams reducible to SC * primitives of algebras of the sixth root of unity Abstract In each of the 10 cases with propagators of unit or zero mass, the finite part of the scalar 3-loop tetrahedral vacuum diagram is reduced to 4-letter words in the 7-letter alphabet of the 1-forms Ω := dz/z and ω p := dz/(λ −p − z), where λ is the sixth root of unity. Three diagrams yield...

The Pomeron loop amplitude and the amplitude for the diagram with any general number of loops is derived in the QCD dipole approach. This provides the necessary tools for solving the long standing theoretical problem of summing over Pomeron loop diagrams. In this theoretical framework the contribution of the full set of enhanced diagrams to the survival probability is estimated. This enables an...