We study a possible explanation of a 3.0 $sigma$ excess recently reported by the ATLAS Collaboration in events with Z-peaked same-flavour opposite-sign lepton pair, jets and large missing transverse momentum in the context of gauge-mediated SUSY brea
king with more than one hidden sector, the so-called goldstini scenario. In a certain parameter space, the gluino two-body decay chain $tilde gto gtildechi^0_{1,2}to gZtilde G$ becomes dominant, where $tildechi^0_{1,2}$ and $tilde G$ are the Higgsino-like neutralino and the massive pseudo-goldstino, respectively, and gluino pair production can contribute to the signal. We find that a mass spectrum such as $m_{tilde g}sim 1000$ GeV, $m_{tildechi^0_{1,2}}sim 800$ GeV and $m_{tilde G}sim 600$ GeV demonstrates the rate and the distributions of the excess, without conflicting with the stringent constraints from jets plus missing energy analyses and with the CMS constraint on the identical final state.
We present the Higgs Characterisation (HC) framework to study the properties of the Higgs boson observed at 125 GeV. In this report, we focus on CP properties of the top-quark Yukawa interaction, and show predictions at next-to-leading order accuracy
in QCD, including parton-shower effects, for Higgs production in association with a single top quark at the LHC.
We present a detailed study of Higgs boson production in association with a single top quark at the LHC, at next-to-leading order accuracy in QCD. We consider total and differential cross sections, at the parton level as well as by matching short dis
tance events to parton showers, for both t-channel and s-channel production. We provide predictions relevant for the LHC at 13 TeV together with a thorough evaluation of the residual uncertainties coming from scale variation, parton distributions, strong coupling constant and heavy quark masses. In addition, for t-channel production, we compare results as obtained in the 4-flavour and 5-flavour schemes, pinning down the most relevant differences between them. Finally, we study the sensitivity to a non-standard-model relative phase between the Higgs couplings to the top quark and to the weak bosons.
Many theories beyond the Standard Model predict the existence of colored scalar states, known as sgluons, lying in the adjoint representation of the QCD gauge group. In scenarios where they are top-philic, sgluons are expected to be copiously pair-pr
oduced at the LHC via strong interactions with decays into pairs of top quarks or gluons. Consequently, sgluons can be sought in multijet and multitop events at the LHC. We revisit two LHC Run I analyses in which events featuring either the same-sign dileptonic decay of a four-top-quark system or its single leptonic decay are probed. Adopting a simplified model approach, we show how this reinterpretation allows us to extract simultaneous bounds on the sgluon mass and couplings.
We introduce a framework, based on an effective field theory approach, that allows one to perform characterisation studies of the boson recently discovered at the LHC, for all the relevant channels and in a consistent, systematic and accurate way. Th
e production and decay of such a boson with various spin and parity assignments can be simulated by means of multi-parton, tree-level matrix elements and of next-to-leading order QCD calculations, both matched with parton showers. Several sample applications are presented which show, in particular, that beyond-leading-order effects in QCD have non-trivial phenomenological implications.
We explore how the polarization of the tau leptons in the cascade decay $tilde{q}to qtildechi^0_2to qtautildetauto qtautautildechi^0_1$ can be exploited to study mixing properties of neutralinos and staus. We present details of the analysis including
experimental effects such as transverse momentum cuts for the $tautopi u$ decay mode, and show that the di-pion invariant mass distribution provides valuable information on their properties.
