Differential equations and massive two-loop Bhabha scattering: the B5l2m3 case

The two-loop box contributions to massive Bhabha scattering may be reduced to two-loop box master integrals (MIs) with five, six, and seven internal lines, plus vertices and self energies. The self-energy and vertex MIs may be solved analytically by the differential equations (DE) method. This is true for only few of the box masters. Here we describe some details of the analytical determination, including constant terms in ep=(4-d)/2, of the complicated topology B5l2m3 (with 5 lines, 2 of them being massive). With the DE approach, three of the four coupled masters have been solved in terms of (generalized) standard Harmonic Polylogarithms.Comment: 5 pages, 2 figures, contribution to RADCOR 2005, Oct 2-7, 2005, Shonan Village, Japan, to appear in Nucl. B (Proc. Suppl.

The Muon Decay at the Two Loop Level of the Electroweak Interactions

The progress in the evaluation of the muon decay lifetime is reviewed. The electroweak bosonic corrections are given together with the respective shift of the W boson mass. After inclusion of the recently corrected fermionic contributions, this requires an updated fitting formula for the prediction of MW.Comment: Invited talk at the XXIII Physics in Collisions Conference (PIC03), Zeuthen, Germany, June 2003, 3 pages, LaTeX, 2 eps figures. PSN FRAP2

The soft function for color octet production at threshold

We evaluate the next-to-next-to-leading order soft function for the production of a massive color octet state at rest in the collision of two massless colored partons in either the fundamental or the adjoint representation. The main application of our result is the determination of the threshold expansion of the heavy-quark pair-production cross sections in the quark annihilation and gluon fusion channels. We discuss the factorization necessary for this purpose and explain the relationship between hard functions and virtual amplitudes.Comment: 18 pages, 5 figures, references added, matches published versio

Massive particle production to NNLO in QCD

We discuss the recent derivation of the one-loop squared virtual QCD corrections to the W boson pair production in the quark-anti-quark-annihilation channel in the limit where all kinematical invariants are large compared to the mass of the W boson. In particular, we elaborate on the combined use of the helicity matrix formalism with the Mellin-Barnes representations technique.Comment: Presented at "Loops and Legs in Quantum Field Theory", Sondershausen, 20-25 April 2008, 5 page

Precision top pair production at hadron colliders

We demonstrate the impact of recent NNLO calculations on precision top quark phenomenology.Comment: Based on talks given at the 11th DESY Workshop "Loops and Legs in Quantum Field Theory 2012", the 7th International Workshop on the CKM Unitarity Triangle "CKM 2012" and the 5th International Workshop on Top Quark Physics "Top 2012

Four-dimensional formulation of the sector-improved residue subtraction scheme

Four years ago, one of us introduced a novel subtraction scheme for the evaluation of double-real radiation contributions to cross sections at next-to-next-to-leading order (NNLO) in QCD. This approach, named SecToR Improved Phase sPacE for Real radiation (STRIPPER), has already found several non-trivial applications. In particular, it has allowed for the determination of NNLO corrections to hadronic top-quark pair production, fully differential top-quark decays, inclusive semileptonic charmless b-quark decays, associated Higgs boson and jet production in gluon fusion, muon decay spin asymmetry, and t-channel single-top production. Common to these calculations was the use of conventional dimensional regularization (CDR). In this publication, we present a complete formulation of the subtraction scheme for arbitrary processes with any number of colored partons in the final state, and up to two partons in the initial state. Furthermore, we modify the integrated subtraction terms of the double-real radiation to enable the introduction of the 't Hooft-Veltman version of dimensional regularization (HV), in which resolved states are four-dimensional. We demonstrate the correctness of our approach on the example of top-quark pair production in the gluon fusion channel.Comment: 60 pages, 5 figures, 9 table

Top++: a program for the calculation of the top-pair cross-section at hadron colliders

We present the program Top++ for the numerical evaluation of the total inclusive cross-section for producing top quark pairs at hadron colliders. The program calculates the cross-section in a) fixed order approach with exact next-to-next-to leading order (NNLO) accuracy and b) by including soft-gluon resummation for the hadronic cross-section in Mellin space with full next-to-next-to-leading logarithmic (NNLL) accuracy. The program offers the user significant flexibility through the large number (29) of available options. Top++ is written in C++. It has a very simple to use interface that is intuitive and directly reflects the physics. The running of the program requires no programing experience from the user.Comment: v2.0: Major update: includes full NNLO result; functionality updates. Program webpage: http://www.alexandermitov.com/softwar

Single chargino production with R-parity lepton number violation in electron-electron and muon-muon collisions

We examine single chargino production in conjunction with R-parity lepton number violation in future lepton-lepton collisions. Present bounds on R-parity violating couplings allow for a production cross section of the order of ${\cal{O}} (10 {fb})$ for a wide range of sneutrino and chargino masses. Scenarios of chargino decay which lead to purely leptonic signals in the final state and without missing energy are also discussed.Comment: Unfortunate mistake in the list of authors corrected, 10 pages, 4 figure

Threshold expansion of the gg(qq) -> QQ+X cross section at O(alpha_s^4)

We derive the complete set of velocity-enhanced terms in the expansion of the total cross section for heavy-quark pair production in hadronic collisions at next-to-next-to-leading order. Our expression takes into account the effects of soft-gluon emission as well as that of potential-gluon exchanges. We prove that there are no enhancements due to subleading soft-gluon couplings multiplying the leading Coulomb singularity.Comment: 11 pages, 2 figures, published erratum included at the end of the paper, updated attached Mathematica fil