Motivated by recent claims of lines in the Fermi gamma-ray spectrum, we critically examine means of enhancing neutralino annihilation into neutral gauge bosons. The signal can be boosted while remaining consistent with continuum photon constraints if a new singlet-like pseudoscalar is present. We consider singlet extensions of the MSSM, focusing on the NMSSM, where a `well-tempered' neutralino can explain the lines while remaining consistent with current constraints. We adopt a complementary numerical and analytic approach throughout in order to gain intuition for the underlying physics. The scenario requires a rich spectrum of light neutralinos and charginos leading to characteristic phenomenological signatures at the LHC whose properties we explore. Future direct detection prospects are excellent, with sizeable spin-dependent and spin-independent cross-sections.

In this article the stability of the Standard Model (SM) vacuum in the presence of radiative corrections and for a Higgs boson with a mass in the vicinity of $125$ GeV is discussed. The central piece in this discussion will be the Higgs self-interaction $\lambda$ and its evolution with the energy scale of a given physical process. This is described by the $\beta$-function to which we recently computed analytically the dominant three-loop contributions. These are mainly the QCD and top-Yukawa corrections as well as the contributions from the Higgs self-interaction itself. We will see that for a Higgs boson with a mass of about $125$ GeV the question whether the SM vacuum is stable and therefore whether the SM could be valid up to Planck scale cannot be answered with certainty due to large experimental uncertainties, mainly in the top quark mass.

We consider the application of the DRA method to the case of several master integrals in a given sector. We establish a connection between the homogeneous part of dimensional recurrence and maximal unitarity cuts of the corresponding integrals: a maximally cut master integral appears to be a solution of the homogeneous part of the dimensional recurrence relation. This observation allows us to make a necessary step of the DRA method, the construction of the general solution of the homogeneous equation, which, in this case, is a coupled system of difference equations.

In this paper we compute the four-loop corrections to the QED photon

self-energy $\Pi(Q^2)$ in the two limits of $q = 0$ and $Q^2 \to
\infty$. These results are used to explicitly construct the conversion
relations between the QED charge renormalized in on-shell(OS) and $\MSbar$
scheme. Using these relations and results of Baikov et al. \cite{Baikov:2012zm} we
construct the momentum dependent part of $\Pi(Q^2,m,\alpha)$ at
large $Q^2$ at five loops in both $\MSbar$ and OS schemes.  As a direct
consequence we arrive at the full result for the QED $\beta$-function
in the OS scheme at five loops. These results are applied, in turn, to
analytically evaluate a class of asymptotic contributions to the muon
anomaly at five and six loops.

This class of diagrams has numerous applications. Many interesting results have been obtained for it.

The classical Lagrangian of chromodynamics, its quantization in the perturbation theory framework, and renormalization form the subject of these lectures. Symmetries of the theory are discussed. The dependence of the coupling constant \alpha_s on the renormalization scale \mu is considered in detail.

We present the computation of the loop-induced self-annihilation of dark matter particles into two photons in the framework of the NMSSM. This process is a theoretically clean observable with a “smoking-gun” signature but is experimentally very challenging to detect. The rates were computed with the help of the SloopS program, an automatic code initially designed for the evaluation of processes at the one-loop level in the MSSM. We focused on a light neutralino scenario and discuss how the signal can be enhanced in the NMSSM with respect to the MSSM and then compared with the present limits given by the dedicated search of the FERMI-LAT satellite on the monochromatic gamma lines.