Browsing by Author "Diaz, Marco A."

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    Production of Upsilon(nS) mesons in Pb plus Pb and pp collisions at 5.02 TeV
    (Amer Physical Soc., 2023) Aad, G.; Abbott, B.; Abbott, D. C.; Abeling,, K.; Abidi, S. H.; Aboulhorma, A.; Abramowicz, H.; Abreu, H.; Abulaiti, Y.; Abusleme Hoffman, Angel Christian; Acharya, B. S.; Achkar, B.; Adam, L.; Adamczyk, L.; Adamek, L.; Addepalli, S. V.; Bourdarios, Adam; Diaz, Marco A.; Garay Walls, Francisca Montserrat; ATLAS Collaboration
    A measurement of the production of vector bottomonium states, Upsilon(1S), Upsilon(2S), and Upsilon(3S), in Pb + Pb and pp collisions at a center-of-mass energy per nucleon pair of 5.02 TeV is presented. The data correspond to integrated luminosities of 1.38 nb(-1) of Pb + Pb data collected in 2018, 0.44 nb-1 of Pb + Pb data collected in 2015, and 0.26 fb(-1) of pp data collected in 2017 by the ATLAS detector at the Large Hadron Collider. The measurements are performed in the dimuon decay channel for transverse momentum p(T)(mu mu) < 30 GeV, absolute rapidity vertical bar y(mu mu)vertical bar < 1.5, and Pb + Pb event centrality 0-80%. The production rates of the three bottomonium states in Pb + Pb collisions are compared with those in pp collisions to extract the nuclear modification factors as functions of event centrality, p(T)(mu mu), and vertical bar y(mu mu)vertical bar. In addition, the suppression of the excited states relative to the ground state is studied. The results are compared with theoretical model calculations.
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    Revisiting the scotogenic model with scalar dark matter
    (2022) Avila, Ivania M.; Cottin, Giovanna; Diaz, Marco A.
    The scotogenic model is a well motivated scenario that provides both an explanation for neutrino masses and for dark matter (DM). We focus on a real scalar DM candidate in this model, produced through standard thermal freeze-out. We analyze the parameter space of the model compatible with the observed DM relic abundance, direct and indirect detection searches, limits from lepton flavour violating decays and constraints from the neutrino sector. As the mass differences of the DM with the neutral and charged states are found to be small, the new scalars and fermions of the theory will have macroscopic lifetimes, and could thus be potentially detected with long-lived particle signatures at colliders. We find regions in the parameter space to be-partially or fully-consistent with the DM relic abundance, and the prediction of a long-lived charged scalar or lightest neutral fermion in the scotogenic scenario, for DM masses below 500 GeV. We discuss on the collider phenomenology in some detail.