On The {\it Fermi} -Lat Surplus of the Diffuse Galactic Gamma-Ray Emission

Recent observations of the diffuse Galactic \gr emission (DGE) by the {\it Fermi} Large Area Telescope ({\it Fermi}-LAT) have shown significant deviations, above a few GeV until about 100 GeV, from DGE models that use the GALPROP code for the propagation of cosmic ray (CR) particles outside their sources in the Galaxy and their interaction with the target distributions of the interstellar gas and radiation fields. The surplus of radiation observed is most pronounced in the inner Galaxy, where the concentration of CR sources is strongest. The present study investigates this "{\it Fermi}-LAT Galactic Plane Surplus" by estimating the \gr emission from the sources themselves, which is disregarded in the above DGE models. It is shown that indeed the expected hard spectrum of CRs, still confined in their sources (SCRs), can explain this surplus. The method is based on earlier studies regarding the so-called EGRET GeV excess which by now is generally interpreted as an instrumental effect. The contribution from SCRs is predicted to increasingly exceed the DGE models also above 100 GeV, up to \gr energies of about ten TeV, where the corresponding surplus exceeds the hadronic part of the DGE by about one order of magnitude. Above such energies the emission surplus should decrease again with energy due to the finite life-time of the assumed supernova remnant sources. Observations of the DGE in the inner Galaxy at 15 TeV with the Milagro \gr detector and, at TeV energies, with the ARGO-YBJ detector are interpreted to provide confirmation of a significant SCR contribution to the DGE.Comment: 6 pages, 1 figure. Accepted for publication in The Astrophysical Journal, 2013; added referenc

Is a Large Intrinsic k_T Needed to Describe Photon + Jet Photoproduction at HERA?

We study the photoproduction of an isolated photon and a jet based on a code of partonic event generator type which includes the full set of next-to-leading order corrections. We compare our results to a recent ZEUS analysis in which an effective k_T of the incoming partons has been determined. We find that no additional intrinsic k_T is needed to describe the data.Comment: 23 pages LaTeX, 12 figure

Isolated prompt photon photoproduction at NLO

We present a full next-to-leading order code to calculate the photoproduction of prompt photons. The code is a general purpose program of partonic event generator type with large flexibility. We study the possibility to constrain the photon structure functions and comment on isolation issues. A comparison to ZEUS data is also shown.Comment: 22 pages LaTeX, 15 figure

A NLO calculation of the hadron-jet cross section in photoproduction reactions

We study the photoproduction of large-p_T charged hadrons in e p collisions, both for the inclusive case and for the case where a jet in the final state is also measured. Our results are obtained by a NLO generator of partonic events. We discuss the sensitivity of the cross section to the renormalisation and factorisation scales, and to various fragmentation function parametrisations. The possibility to constrain the parton densities in the proton and in the photon is assessed. Comparisons are made with H1 data for inclusive charged hadron production.Comment: 28 pages LaTeX, 14 figure

Tools for NLO automation: extension of the golem95C integral library

We present an extension of the program golem95C for the numerical evaluation of scalar integrals and tensor form factors entering the calculation of one-loop amplitudes, which supports tensor ranks exceeding the number of propagators. This extension allows various applications in Beyond the Standard Model physics and effective theories, for example higher ranks due to propagators of spin two particles, or due to effective vertices. Complex masses are also supported. The program is not restricted to the Feynman diagrammatic approach, as it also contains routines to interface to unitarity-inspired numerical reconstruction of the integrand at the tensorial level. Therefore it can serve as a general integral library in automated programs to calculate one-loop amplitudes.Comment: 17 pages, 1 figure, the program can be downloaded from http://golem.hepforge.org/95/. arXiv admin note: substantial text overlap with arXiv:1101.559

Next-to-leading order multi-leg processes for the Large Hadron Collider

In this talk we discuss recent progress concerning precise predictions for the LHC. We give a status report of three applications of our method to deal with multi-leg one-loop amplitudes: The interference term of Higgs production by gluon- and weak boson fusion to order O(alpha^2 alpha_s^3) and the next-to-leading order corrections to the two processes pp -> ZZ jet and u ubar -> d dbar s sbar. The latter is a subprocess of the four jet cross section at the LHC.Comment: 6 pages, 5 figures. Talk given at the 8th international Symposium on Radiative Corrections (RADCOR), October 1-5 2007, Florence, Ital

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

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

Damping by slow relaxing rare earth impurities in Ni80Fe20

Doping NiFe by heavy rare earth atoms alters the magnetic relaxation properties of this material drastically. We show that this effect can be well explained by the slow relaxing impurity mechanism. This process is a consequence of the anisotropy of the on site exchange interaction between the 4f magnetic moments and the conduction band. As expected from this model the magnitude of the damping effect scales with the anisotropy of the exchange interaction and increases by an order of magnitude at low temperatures. In addition our measurements allow us to determine the relaxation time of the 4f electrons as a function of temperature