We study the decays of a scalar (t̃1t̃ ∗ 1) bound state σt̃1 , where t̃1 is the lighter stop eigenstate. If t̃1 has no tree–level 2–body decays, the dominant decay modes of σt̃1 are gg or, if mh < mt̃1 ≪ mt̃2 , a pair of light scalar Higgs bosons h. The best signal for σt̃1 production at hadron colliders is probably its decay into two photons. Contribution to the Proceedings of the Madison–Argonne Hadro...

We perform a preliminary study of the ability of the Higgs decay to four leptons to shed light on the top quark Yukawa couplings. In particular we examine whether the h → 4l “golden channel” is sensitive to the CP properties of the top quark couplings to the Higgs boson. We show that kinematic distributions are sensitive to interference of the next-to-leading order electroweak corrections with ...

Impact of LSP Character on Slepton Reach at the LHC Jonathan Eckel1∗, Michael J. Ramsey-Musolf2,3†, William Shepherd4,5‡, Shufang Su1§ 1 Department of Physics, University of Arizona, Tucson, AZ 85721 2 Amherst Center for Fundamental Interactions, Department of Physics University of Massachusetts-Amherst, Amherst, MA 01003 3 Kellogg Radiation Laboratory, California Institute of Technology, Pasad...

At the LHC a precise measurement of the Higgs boson mass (if discovered), at the level of 0.1-1%, will be possible through the channel gg → H → 4l for a wide range of Higgs mass values. To match such an accuracy, the systematic effects induced by QED corrections need to be investigated. In the present study the calculation of O(α) and higher order QED corrections is illustrated as well as their...

A cosmological first order electroweak phase transition could explain the origin of the cosmic matter-antimatter asymmetry. While it does not occur in the Standard Model, it becomes possible in the presence of a second Higgs doublet. In this context, we obtain the properties of the new scalars H0, A0 and H ± leading to such a phase transition, showing that its key LHC signature would be the dec...

The lepton–number violating process ep → νe(νe)llX mediated by Majorana neutrinos is studied for the HERA collider for (ll) = (eτ), (μτ), (μμ) and (ττ). Only the muonic decay of the τ is considered. The direct limit on the effective muon Majorana mass, 〈mμμ〉 is improved significantly to 4.0 · 103 GeV and for the first time direct limits on the analogous effective masses connected with the tau s...

The results of a search for gluinos in final states with an isolated electron or muon, multiple jets and large missing transverse momentum using proton–proton collision data at a centre-of-mass energy of √ s = 13 TeV are presented. The dataset used was recorded in 2015 by the ATLAS experiment at the Large Hadron Collider and corresponds to an integrated luminosity of 3.2 fb −1. Six signal selec...

Multi-lepton signatures appear in many new physics searches at the Large Hadron Collider. We here consider WWZ production with subsequent leptonic decay of the three vector bosons as a SM source of multi-lepton events. We have calculated the next-to-leading order QCD corrections for the full pp → 6 lepton production cross sections in hadronic collisions. Results have been implemented in the for...

We discuss the search for the heavy charged Higgs bosons H, implicitly of the Minimal Supersymmetric Standard Model, in the τν decay mode at the LHC. Compared to the dominant decay mode H → bt, the channel suffers from suppression due to the branching ratio and the lack of direct mass reconstruction, but the reduced Qcd background makes it a feasible channel especially in the large tan β region...