S. P. Jones

Higgs Boson Pair Production in Gluon Fusion at Next-to-Leading Order with Full Top-Quark Mass Dependence.

We present the calculation of the cross section and invariant mass distribution for Higgs boson pair production in gluon fusion at next-to-leading order (NLO) in QCD. Top-quark masses are fully taken into account throughout the calculation. The virtual two-loop amplitude has been generated using an extension of the program GoSam supplemented with an interface to Reduze for the integral reduction. The occurring integrals have been calculated numerically using the program SecDec. Our results, including the full top-quark mass dependence for the first time, allow us to assess the validity of various approximations proposed in the literature, which we also recalculate. We find substantial deviations between the NLO result and the different approximations, which emphasizes the importance of including the full top-quark mass dependence at NLO.

Full top quark mass dependence in Higgs boson pair production at NLO

A bstractWe study the effects of the exact top quark mass-dependent two-loop corrections to Higgs boson pair production by gluon fusion at the LHC and at a 100 TeV hadron collider. We perform a detailed comparison of the full next-to-leading order result to various approximations at the level of differential distributions and also analyse non-standard Higgs self-coupling scenarios. We find that the different next-to-leading order approximations differ from the full result by up to 50 percent in relevant differential distributions. This clearly stresses the importance of the full NLO result.We study the effects of the exact top quark mass-dependent two-loop corrections to Higgs boson pair production by gluon fusion at the LHC and at a 100 TeV hadron collider. We perform a detailed comparison of the full next-to-leading order result to various approximations at the level of differential distributions and also analyse non-standard Higgs self-coupling scenarios. We find that the different next-toleading order approximations differ from the full result by up to 50 percent in relevant differential distributions. This clearly stresses the importance of the full NLO result.

pySecDec: a toolbox for the numerical evaluation of multi-scale integrals

Abstract We present py SecDec , a new version of the program SecDec , which performs the factorization of dimensionally regulated poles in parametric integrals, and the subsequent numerical evaluation of the finite coefficients. The algebraic part of the program is now written in the form of python modules, which allow a very flexible usage. The optimization of the C++ code, generated using FORM , is improved, leading to a faster numerical convergence. The new version also creates a library of the integrand functions, such that it can be linked to user-specific codes for the evaluation of matrix elements in a way similar to analytic integral libraries. Program summary Program Title: pySecDec Program Files doi: http://dx.doi.org/10.17632/3y8bbz9c9v.1 Licensing provisions: GNU Public License v3 Programming language: python, FORM, C++ External routines/libraries: catch [1], gsl [2], numpy [3], sympy [4], Nauty [5], Cuba [6], FORM [7], Normaliz [8]. The program can also be used in a mode which does not require Normaliz. Journal reference of previous version: Comput. Phys. Commun. 196 (2015) 470–491. Nature of the problem: Extraction of ultraviolet and infrared singularities from parametric integrals appearing in higher order perturbative calculations in quantum field theory. Numerical integration in the presence of integrable singularities (e.g. kinematic thresholds). Solution method: Algebraic extraction of singularities within dimensional regularization using iterated sector decomposition. This leads to a Laurent series in the dimensional regularization parameter ϵ (and optionally other regulators), where the coefficients are finite integrals over the unit-hypercube. Those integrals are evaluated numerically by Monte Carlo integration. The integrable singularities are handled by choosing a suitable integration contour in the complex plane, in an automated way. The parameter integrals forming the coefficients of the Laurent series in the regulator(s) are provided in the form of libraries which can be linked to the calculation of (multi-) loop amplitudes. Restrictions: Depending on the complexity of the problem, limited by memory and CPU time. References: [1] https://github.com/philsquared/Catch/ . [2] http://www.gnu.org/software/gsl/ . [3] http://www.numpy.org/ . [4] http://www.sympy.org/ . [5] http://pallini.di.uniroma1.it/ . [6] T. Hahn, “CUBA: A Library for multidimensional numerical integration,” Comput. Phys. Commun. 168 (2005) 78 [hep-ph/0404043], http://www.feynarts.de/cuba/ . [7] J. Kuipers, T. Ueda and J. A. M. Vermaseren, “Code Optimization in FORM,” Comput. Phys. Commun. 189 (2015) 1 [arXiv:1310.7007], http://www.nikhef.nl/ form/ . [8] W. Bruns, B. Ichim, B. and T. Romer, C. Soger, “Normaliz. Algorithms for rational cones and affine monoids.” http://www.math.uos.de/normaliz/ .

NLO predictions for Higgs boson pair production with full top quark mass dependence matched to parton showers

A bstractWe present the first combination of NLO QCD matrix elements for di-Higgs production, retaining the full top quark mass dependence, with a parton shower. Results are provided within both the POWHEG-BOX and MadGraph5_aMC@NLO Monte Carlo frameworks. We assess in detail the theoretical uncertainties and provide differential results. We find that, as expected, the shower effects are relatively large for observables like the transverse momentum of the Higgs boson pair, which are sensitive to extra radiation. However, these shower effects are still much smaller than the differences between the Born-improved HEFT approximation and the full NLO calculation in the tails of the distributions.

NNLO predictions for Z-boson pair production at the LHC

A bstractWe present a calculation of the NNLO QCD corrections to Z-boson pair production at hadron colliders, based on the N-jettiness method for the real radiation parts. We discuss the size and shape of the perturbative corrections along with their associated scale uncertainties and compare our results to recent LHC data at s=13

Numerical multi-loop calculations: tools and applications

\sqrt{s}=13

Erratum: Higgs Boson Pair Production in Gluon Fusion at Next-to-Leading Order with Full Top-Quark Mass Dependence [Phys. Rev. Lett. 117 , 012001 (2016)]

TeV.

Parton shower and NLO-matching uncertainties in Higgs boson pair production

A bstractWe consider QCD radiative corrections to Higgs boson pair production through gluon fusion in proton collisions. We combine the exact next-to-leading order (NLO) contribution, which features two-loop virtual amplitudes with the full dependence on the top quark mass Mt, with the next-to-next-to-leading order (NNLO) corrections computed in the large-Mt approximation. The latter are improved with different reweighting techniques in order to account for finite-Mt effects beyond NLO. Our reference NNLO result is obtained by combining one-loop double-real corrections with full Mt dependence with suitably reweighted real-virtual and double-virtual contributions evaluated in the large-Mt approximation. We present predictions for inclusive cross sections in pp collisions at s