378 research outputs found
SecDec-3.0: numerical evaluation of multi-scale integrals beyond one loop
SecDec is a program which can be used for the factorization of dimensionally
regulated poles from parametric integrals, in particular multi-loop integrals,
and the subsequent numerical evaluation of the finite coefficients. Here we
present version 3.0 of the program, which has major improvements compared to
version 2: it is faster, contains new decomposition strategies, an improved
user interface and various other new features which extend the range of
applicability.Comment: 46 pages, version to appear in Comput.Phys.Com
Numerical evaluation of two-loop integrals with pySecDec
We describe the program pySecDec, which factorises endpoint singularities
from multi-dimensional parameter integrals and can serve to calculate integrals
occurring in higher order perturbative calculations numerically. We focus on
the new features and on frequently asked questions about the usage of the
program.Comment: 11 pages, to appear in the proceedings of the HiggsTools Final
Meeting, IPPP, University of Durham, UK, September 201
Projective geometry and the quaternionic Feix-Kaledin construction
Starting from a complex manifold S with a real-analytic c-projective structure whose curvature has type (1, 1), and a complex line bundle L → S with a connection whose curvature has type (1, 1), we construct the twistor space Z of a quaternionic manifold M with a quaternionic circle action which contains S as a totally complex submanifold fixed by the action. This extends a construction of hypercomplex manifolds, including hyperkähler metrics on cotangent bundles, obtained independently by Feix and Kaledin. When S is a Riemann surface, M is a self-dual conformal 4-manifold and the quotient of M by the circle action is an Einstein–Weyl manifold with an asymptotically hyperbolic end, and our construction coincides with the construction presented by Borówka. The extension also applies to quaternionic Kähler manifolds with circle actions, as studied by Haydys and Hitchin.</p
Higgs boson pair production in gluon fusion at NLO 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.Comment: Version published in PRL, v2: results at 13 TeV (v1 was at 14 TeV),
minor correction to virtual part included, conclusions unchange
Loopedia, a Database for Loop Integrals
Loopedia is a new database at loopedia.org for information on Feynman
integrals, intended to provide both bibliographic information as well as
results made available by the community. Its bibliometry is complementary to
that of SPIRES or arXiv in the sense that it admits searching for integrals by
graph-theoretical objects, e.g. its topology.Comment: 16 pages, lots of screenshot
Projective geometry and the quaternionic Feix-Kaledin construction
Starting from a complex manifold S with a real-analytic c-projective
structure whose curvature has type (1,1), and a complex line bundle L with a
connection whose curvature has type (1,1), we construct the twistor space Z of
a quaternionic manifold M with a quaternionic circle action which contains S as
a totally complex submanifold fixed by the action. This extends a construction
of hypercomplex manifolds, including hyperkaehler metrics on cotangent bundles,
obtained independently by B. Feix and D. Kaledin.
When S is a Riemann surface, M is a self-dual conformal 4-manifold, and the
quotient of M by the circle action is an Einstein-Weyl manifold with an
asymptotically hyperbolic end, and our construction coincides with a
construction presented by the first author in a previous paper. The extension
also applies to quaternionic Kaehler manifolds with circle actions, as studied
by A. Haydys and N. Hitchin.Comment: 28 pages, (v2) added material on Swann bundles, quaternionic Kaehler
metrics and the Haydys-Hitchin correspondence, (v3) refereed version,
restructured content, to appear in TAM
pySecDec: a toolbox for the numerical evaluation of multi-scale integrals
We present pySecDec, 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
- …