4,861 research outputs found
Finite Quantum Gravity
We hereby present a class of multidimensional higher derivative theories of
gravity that realizes an ultraviolet completion of Einstein general relativity.
This class is marked by a "non-polynomal" entire function (form factor), which
averts extra degrees of freedom (including ghosts) and improves the high energy
behavior of the loop amplitudes. By power counting arguments, it is proved that
the theory is super-renormalizable in any dimension, i.e. only one-loop
divergences survive. Furthermore, in odd dimensions there are no counter terms
for pure gravity and the theory turns out to be "finite." Finally, considering
the infinite tower of massive states coming from dimensional reduction, quantum
gravity is finite in even dimension as well.Comment: 19 pages. arXiv admin note: substantial text overlap with
arXiv:1202.315
Massive Nonplanar Two-Loop Maximal Unitarity
We explore maximal unitarity for nonplanar two-loop integrals with up to four
massive external legs. In this framework, the amplitude is reduced to a basis
of master integrals whose coefficients are extracted from maximal cuts. The
hepta-cut of the nonplanar double box defines a nodal algebraic curve
associated with a multiply pinched genus-3 Riemann surface. All possible
configurations of external masses are covered by two distinct topological
pictures in which the curve decomposes into either six or eight Riemann
spheres. The procedure relies on consistency equations based on vanishing of
integrals of total derivatives and Levi-Civita contractions. Our analysis
indicates that these constraints are governed by the global structure of the
maximal cut. Lastly, we present an algorithm for computing generalized cuts of
massive integrals with higher powers of propagators based on the Bezoutian
matrix method.Comment: 54 pages, 9 figures, v2: journal versio
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
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