Abstract: A search for new phenomena in final states characterized by high jet multiplicity, an isolated lepton ( electron or muon) and either zero or at least three b-tagged jets is presented. The search uses 36.1 fb(-1) of root s = 13TeV proton-proton collision data collected by the ATLAS experiment at the Large Hadron Collider in 2015 and 2016. The dominant sources of background are estimated using parameterized extrapolations, based on observables at medium jet multiplicity, to predict the b-tagged jet multiplicity distribution at the higher jet multiplicities used in the search. No significant excess over the Standard Model expectation is observed and 95% confidence-level limits are extracted constraining four simplified models of R-parity-violating supersymmetry that feature either gluino or top-squark pair production. The exclusion limits reach as high as 2.1TeV in gluino mass and 1.2TeV in top-squark mass in the models considered. In addition, an upper limit is set on the cross-section for Standard Model t (t) over bart (t) over bar production of 60 fb (6.5 x the Standard Model prediction) at 95% confidence level. Finally, model-independent limits are set on the contribution from new phenomena to the signal-region yields.

Abstract: Charged Higgs bosons produced either in top-quark decays or in association with a top-quark, subsequently decaying via H-+/-! -> tau(+/-)nu(tau), are searched for in 36.1 fb(-1) of proton-proton collision data at root s = 13TeV recorded with the ATLAS detector. Depending on whether the top-quark produced together with H-+/- decays hadronically or leptonically, the search targets tau+jets and tau+lepton fi nal states, in both cases with a hadronically decaying tau-lepton. No evidence of a charged Higgs boson is found. For the mass range of m(H)+/- = 90-2000 GeV, upper limits at the 95% con fi dence level are set on the production cross-section of the charged Higgs boson times the branching fraction B (H-+/-->tau(+/-)nu(tau)) in the range 4.2-0.0025 pb. In the mass range 90{160 GeV, assuming the Standard Model cross-section for tit production, this corresponds to upper limits between 0.25% and 0.031% for the branching fraction B (t -> bH(+/-)) x B (H-+/- -> tau(+/-)nu(tau)).

Abstract: We investigate the possibility of viable leptogenesis in an appealing Delta(27) model with a universal texture zero in the (1,1) entry. The model accommodates the mass spectrum, mixing and CP phases for both quarks and leptons and allows for grand unification. Flavoured Boltzmann equations for the lepton asymmetries are solved numerically, taking into account both N-1 and N-2 right-handed neutrino decays. The N-1-dominated scenario is successful and the most natural option for the model, with M-1 is an element of [10(9), 10(12)] GeV, and M-1/M-2 is an element of [0.002, 0.1], which constrains the parameter space of the underlying model and yields lower bounds on the respective Yukawa couplings. Viable leptogenesis is also possible in the N-2-dominated scenario, with the asymmetry in the electron flavour protected from N-1 washout by the texture zero. However, this occurs in a region of parameter space which has a stronger mass hierarchy M-1/M-2< 0.002, and M-2 relatively close to M-3, which is not a natural expectation of the Delta(27) model.

Abstract: The presence of new neutrino-quark interactions can enhance, deplete or distort the coherent elastic neutrino-nucleus scattering (CEvNS) event rate. The new interactions may involve CP violating phases that can potentially affect these features. Assuming light vector mediators, we study the effects of CP violation on the CEvNS process in the COHERENT sodium-iodine, liquid argon and germanium detectors. We identify a region in parameter space for which the event rate always involves a dip and another one for which this is never the case. We show that the presence of a dip in the event rate spectrum can be used to constraint CP violating effects, in such a way that the larger the detector volume the tighter the constraints. Furthermore, it allows the reconstruction of the effective coupling responsible for the signal with an uncertainty determined by recoil energy resolution. In the region where no dip is present, we find that CP violating parameters can mimic the Standard Model CEvNS prediction or spectra induced by real parameters. We point out that the interpretation of CEvNS data in terms of a light vector mediator should take into account possible CP violating effects. Finally, we stress that our results are qualitatively applicable for CEvNS induced by solar or reactor neutrinos. Thus, the CP violating effects discussed here and their consequences should be taken into account as well in the analysis of data from multi-ton dark matter detectors or experiments such as CONUS, nu-cleus or CONNIE.

Abstract: We study for the first time the case in which Dark Matter (DM) is made of Feebly Interacting Massive Particles (FIMP) interacting just gravitationally with the standard model particles in an extra-dimensional Randall-Sundrum scenario. We assume that both the dark matter and the standard model are localized in the IR-brane and only interact via gravitational mediators, namely the graviton, the Kaluza-Klein gravitons and the radion. We found that in the early Universe DM could be generated via two main processes: the direct freeze-in and the sequential freeze-in. The regions where the observed DM relic abundance is produced are largely compatible with cosmological and collider bounds.