Unitarity cuts diverge in the channel of a single massive external fermion. We propose an off-shell continuation of the momentum that allows a finite evaluation of the unitarity cuts. If the cut is ...taken with complete amplitudes on each side, our continuation and expansion around the on-shell configuration produces the finite contribution to the bubble coefficient. Finite parts in the expansion of the external leg counterterms must be included explicitly as well.
We present an extension of the spinor integration formalism of one loop amplitudes from the double-cut to the single-cut case. This technique can be applied for the computation of the tadpole ...coefficients. Moreover we describe an off-shell continuation of one loop amplitudes that allows a finite evaluation of the unitarity cuts in the channel of a single massive external fermion.
We present an analytic technique for evaluating single cuts for one-loop integrands, where exactly one propagator is taken to be on shell. Our method extends the double-cut integration formalism of ...one-loop amplitudes to the single-cut case. We argue that single cuts give meaningful information about amplitudes when taken at the integrand level. We discuss applications to the computation of tadpole coefficients.
We present the calculation of the electroweak corrections for squark-antisquark pair production at the LHC within the Minimal Supersymmetric Standard Model. Taking into account all possible chirality ...and light-flavor configurations, we evaluate the NLO EW corrections, which are of O(a_s^2 a), as well as the subleading tree-level contributions of O(a_s a) and O(a^2). Numerical results are presented for several scans in the SUSY parameter space and relevant differential distributions are investigated. The impact of the electroweak corrections is nonnegligible and strongly depends on the chirality configuration of the produced squarks. Our analysis includes a discussion of photon-gluon initiated processes with a focus on the impact of the corresponding large PDF uncertainties.
We present the complete NLO electroweak contribution of \(\mathcal{O}(\alpha^2_s \alpha)\) to the production of diagonal squark--anti-squark pairs in proton--proton collisions. Compared to the ...lowest-order \(\mathcal{O}(\alpha_s\alpha + \alpha^2)\) electroweak terms, the NLO contributions are also significant. We discuss the LO and NLO electroweak effects in cross sections and distributions at the LHC for the production of squarks different from top squarks, in various supersymmetric benchmark scenarios.
We present a semi-analytic method for the integrand reduction of one-loop amplitudes, based on the systematic application of the Laurent expansions to the integrand-decomposition. In the asymptotic ...limit, the coefficients of the master integrals are the solutions of a diagonal system of equations, properly corrected by counterterms whose parametric form is konwn a priori. The Laurent expansion of the integrand is implemented through polynomial division. The extension of the integrand-reduction to the case of numerators with rank larger than the number of propagators is discussed as well.
We present a complete next-to-leading order study of top-squark pair production at the LHC, including QCD and EW corrections. The calculation is performed within the Minimal Supersymmetric Standard ...Model and numerical results are presented for parameter regions compatible with the observed Higgs boson. We employ the most recent parton distribution functions including QED corrections and we find NLO EW corrections to the inclusive stop-pair production cross section up to \(25 - 30\%\) compared to the leading-order prediction. Besides corrections to inclusive cross sections also important kinematic distributions are investigated.
Presented are the complete NLO electroweak contributions to the production of diagonal squark--anti-squark pairs at the LHC. We discuss their effects for the production of squarks of the first two ...generations, in different SUSY scenarios.
We present the complete NLO electroweak contribution to the production of diagonal squark--anti-squark pairs in proton--proton collisions. We discuss their effects for the production of squarks ...different from top squarks, in the SPS1a' scenario.
We present the complete computation of the tree-level and the next-to-leading order electroweak contributions to bottom-squark pair production at the LHC. The computation is performed within the ...minimal supersymmetric extension of the Standard Model. We discuss the numerical impact of these contributions in several supersymmetric scenarios.
