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Traditional direct searches for dark matter, looking for nuclear recoils in deep underground detectors, are challenged by an almost complete loss of sensitivity for light dark matter particles. Consequently, there is a significant effort in the community to devise new methods and experiments to overcome these difficulties, constantly pushing the limits of the lowest dark matter mass that can be probed this way. From a model-building perspective, the scattering of sub-GeV dark matter on nucleons ...

The dark matter may consist not of one elementary particle but of different species, each of them contributing a fraction of the observed dark matter density. A major theoretical difficulty with this scenario — dubbed multi-component dark matter — is to explain the stability of these distinct particles. Imposing a single ZN symmetry, which may be a remnant of a spontaneously broken U(1) gauge symmetry, seems to be the simplest way to simultaneously stabilize several dark matter particles. In thi...

Search for lepton flavour violating decays of a neutral heavy Higgs boson to μτ and e τ in proton-proton collisions at s$ \sqrt{s} = 13 TeV

A search for lepton flavour violating decays of a neutral non-standard-model Higgs boson in the μτ and eτ decay modes is presented. The search is based on proton-proton collisions at a center of mass energy $ \sqrt{s} = 13 TeV collected with the CMS detector in 2016, corresponding to an integrated luminosity of 35.9 fb−1. The τ leptons are reconstructed in the leptonic and hadronic decay modes. No signal is observed in the mass range 200–900 GeV. At 95% confidence level, the observed (expect...

Effective field theory approach to lepton number violating decays K±→π∓lα±lβ±:$ {K}^{\pm}\to {\pi}^{\mp }{l}_{\alpha}^{\pm }{l}_{\beta}^{\pm }: long-distance contribution

This is a sequel to our recent work [1] in which we calculated the lepton number violating (LNV) K± decays due to contact dimension-9 (dim-9) quark-lepton effective interactions that are induced at a high energy scale. In this work we investigate the long- distance contribution to the decays arising from the exchange of a neutrino. These decays can probe LNV interactions involving the second generation of fermions that are not reach- able in nuclear neutrinoless double-β decays. Our study is com...

The tree-level partonic angular distribution of Standard Model Wγ production possesses a feature known as the Radiation Amplitude Zero (RAZ) where destructive interference causes the cross section to vanish. At the proton level the exact cancellation disappears, however, one can find a dip in the central region of the angular distributions, here called the Radiation Valley (RV). In this paper, we show how the sensitivity for W(lv)γ resonances can be significantly improved if one focuses on event...

New renormalisation group flows of three-dimensional Chern-Simons theories with a single gauge group SU(N ) and adjoint matter are found holographically. These RG flows have an infrared fixed point given by a CFT with $ \mathcal{N} = 3 supersymmetry and SU(2) flavour symmetry. The ultraviolet fixed point is again described by a CFT with either \mathcal{N} = 2 and SU(3) symmetry or \mathcal{N} = 1 and G2 symmetry. The gauge/gravity duals of these RG flows are constructed as domain...

Longitudinal short-distance constraints for the hadronic light-by-light contribution to ( g − 2) μ with large- N c Regge models

While the low-energy part of the hadronic light-by-light (HLbL) tensor can be constrained from data using dispersion relations, for a full evaluation of its contribution to the anomalous magnetic moment of the muon (g − 2)μ also mixed- and high-energy regions need to be estimated. Both can be addressed within the operator product expansion (OPE), either for configurations where all photon virtualities become large or one of them remains finite. Imposing such short-distance constraints (SDCs) on ...

General principles of quantum field theory imply that there exists an operator product expansion (OPE) for Wightman functions in Minkowski momentum space that converges for arbitrary kinematics. This convergence is guaranteed to hold in the sense of a distribution, meaning that it holds for correlation functions smeared by smooth test functions. The conformal blocks for this OPE are conceptually extremely simple: they are products of 3-point functions. We construct the conformal blocks in 2-dime...

We construct 5D, N = 1 supergravity in a 4D, N = 1 superspace with an extra bosonic coordinate. This represents four of the supersymmetries and the associated Poincare symmetries manifestly. The remaining four supersymmetries and the rest of the Poincare symmetries are represented linearly but not manifestly. In the linearized approximation, the action reduces to the known superspace result. As an application of the formalism, we discuss the construction of the 5D gravitational Chern-Simons inva...

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