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Arbelaez, C., Hirsch, M., & Restrepo, D. (2017). Fermionic triplet dark matter in an SO(10)-inspired left-right model. Phys. Rev. D, 95(9), 095034–9pp.
Abstract: We study a left right (LR) extension of the Standard Model (SM) where the Dark Matter(DM) candidate is composed of a set of fermionic Majorana triplets. The DM is stabilized by a remnant Z(2) symmetry from the breaking of the LR group to the SM. Two simple scenarios where the DM particles plus a certain set of extra fields lead to gauge coupling unification with a low LR scale are explored. The constraints from relic density and predictions for direct detection are discussed for both scenarios. The first scenario with a SUd(2)(R) vectorlike fermion triplet contains a DM candidate which is almost unconstrained by current direct detection experiments. The second scenario, with an additional SU(2)R triplet, opens up a scalar portal leading to direct detection constraints which are similar to collider limits for right gauge bosons. The DM parameter space consistent with phenomenological requirements can also lead to successful gauge coupling unification in a SO(10) setup.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Measurement of WW/WZ -> lvqq ' production with the hadronically decaying boson reconstructed as one or two jets in pp collisions at root s=8 TeV with ATLAS, and constraints on anomalous gauge couplings. Eur. Phys. J. C, 77(8), 563–31pp.
Abstract: This paper presents a study of the production of WW or WZ boson pairs, with one W boson decaying to ev or μv and one W or Z boson decaying hadronically. The analysis uses 20.2 fb(-1) of root s = 8 TeV pp collision data, collected by the ATLAS detector at the Large Hadron Collider. Crosssections for WW/WZ production are measured in high-p(T) fiducial regions defined close to the experimental event selection. The cross-section is measured for the case where the hadronically decaying boson is reconstructed as two resolved jets, and the case where it is reconstructed as a single jet. The transverse momentum distribution of the hadronically decaying boson is used to search for new physics. Observations are consistent with the Standard Model predictions, and 95% confidence intervals are calculated for parameters describing anomalous triple gauge-boson couplings.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Study of WW gamma and WZ gamma production in pp collisions at root s=8 TeV and search for anomalous quartic gauge couplings with the ATLAS experiment. Eur. Phys. J. C, 77(9), 646–30pp.
Abstract: This paper presents a study of WW gamma and WZ gamma triboson production using events from proton-proton collisions at a centre-of-mass energy of root s = 8 TeV recorded with the ATLAS detector at the LHC and corresponding to an integrated luminosity of 20.2 fb(-1). The WW gamma production cross-section is determined using a final state containing an electron, a muon, a photon, and neutrinos (e upsilon μupsilon gamma). Upper limits on the production cross-section of the e upsilon μupsilon gamma final state and theWW gamma and WZ gamma final states containing an electron or a muon, two jets, a photon, and a neutrino (e upsilon j j gamma or μupsilon j j gamma) are also derived. The results are compared to the cross-sections predicted by the Standard Model at next-to-leading order in the strong-coupling constant. In addition, upper limits on the production cross-sections are derived in a fiducial region optimised for a search for newphysics beyond the Standard Model. The results are interpreted in the context of anomalous quartic gauge couplings using an effective field theory. Confidence intervals at 95% confidence level are derived for the 14 coupling coefficients to which WW gamma and WZ gamma production are sensitive.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Measurement of detector-corrected observables sensitive to the anomalous production of events with jets and large missing transverse momentum in pp collisions at root s=13 TeV using the ATLAS detector. Eur. Phys. J. C, 77(11), 765–31pp.
Abstract: Observables sensitive to the anomalous production of events containing hadronic jets and missing momentum in the plane transverse to the proton beams at the Large Hadron Collider are presented. The observables are defined as a ratio of cross sections, for events containing jets and large missing transverse momentum to events containing jets and a pair of charged leptons from the decay of a Z/gamma* boson. This definition minimises experimental and theoretical systematic uncertainties in the measurements. This ratio is measured differentially with respect to a number of kinematic properties of the hadronic system in two phase-space regions; one inclusive single-jet region and one region sensitive to vector-boson-fusion topologies. The data are found to be in agreement with the Standard Model predictions and used to constrain a variety of theoretical models for dark-matter production, including simplified models, effective field theory models, and invisible decays of the Higgs boson. The measurements use 3.2 fb(-1) of proton-proton collision data recorded by the ATLAS experiment at a centre-of-mass energy of 13TeV and are fully corrected for detector effects, meaning that the data can be used to constrain new-physics models beyond those shown in this paper.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Barranco Navarro, L., Cabrera Urban, S., Castillo Gimenez, V., Cerda Alberich, L., et al. (2017). Measurement of lepton differential distributions and the top quark mass in t-t bar production in pp collisions a root s=8 TeV with the ATLAS detector. Eur. Phys. J. C, 77(11), 804–66pp.
Abstract: This paper presents single lepton and dilepton kinematic distributions measured in dileptonic t(t)over-bar events produced in 20.2 fb(-1) of root s = 8 TeV pp collisions recorded by the ATLAS experiment at the LHC. Both absolute and normalised differential cross-sections are measured, using events with an opposite-charge e μpair and one or two b-tagged jets. The cross-sections are measured in a fiducial region corresponding to the detector acceptance for leptons, and are compared to the predictions from a variety of Monte Carlo event generators, as well as fixed-order QCD calculations, exploring the sensitivity of the cross-sections to the gluon parton distribution function. Some of the distributions are also sensitive to the top quark pole mass; a combined fit of NLO fixed-order predictions to all the measured distributions yields a top quark mass value of m(t)(pole) = 173.2 +/- 0.9 +/- 0.8 +/- 1.2 GeV, where the three uncertainties arise from data statistics, experimental systematics, and theoretical sources.
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