Yazar "Damanakis, Konstantinos" seçeneğine göre listele

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  • Küçük Resim
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    Observation of the ?(3S) meson and suppression of ? states in Pb-Pb collisions at ?sNN=5.02 TeV
    (American Physical Society, 2024) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, Thomas; Chatterjee, S.; Damanakis, Konstantinos; Dragicevic, M.
    The production of Upsilon(2S) and Upsilon(3S) mesons in lead-lead (Pb-Pb) and proton-proton (pp) collisions is studied in their dimuon decay channel using the CMS detector at the LHC. The Upsilon(3S) meson is observed for the first time in Pb-Pb collisions, with a significance above 5 standard deviations. The ratios of yields measured in Pb-Pb and pp collisions are reported for both the Upsilon(2S) and Upsilon(3S) mesons, as functions of transverse momentum and Pb-Pb collision centrality. These ratios, when appropriately scaled, are significantly less than unity, indicating a suppression of Upsilon yields in Pb-Pb collisions. This suppression increases from peripheral to central Pb-Pb collisions. Furthermore, the suppression is stronger for Upsilon(3S) mesons compared to Upsilon(2S) mesons, extending the pattern of sequential suppression of quarkonium states in nuclear collisions previously seen for the J/psi, psi(2S), Upsilon(1S), and Upsilon(2S) mesons.
  • Küçük Resim
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    Search for resonances in events with photon and jet final states in proton-proton collisions at ?s=13 TeV
    (Springer, 2023) Tumasyan, A.; Adam, W.; Andrejkovic, J. W.; Bergauer, Thomas; Chatterjee, S.; Damanakis, Konstantinos; Dragicevic, M.
    A search for resonances in events with the gamma+jet final state has been performed using proton-proton collision data collected at root s = 13 TeV by the CMS experiment at the LHC. The total data analyzed correspond to an integrated luminosity of 138 fb(-1). Models of excited quarks and quantum black holes are considered. Using a wide-jet reconstruction for the candidate jet, the gamma +jet invariant mass spectrum measured in data is examined for the presence of resonances over the standard model continuum background. The background is estimated by fitting this mass distribution with a functional form. The data exhibit no statistically significant deviations from the expected standard model background. Exclusion limits at 95% confidence level on the resonance mass and other parameters are set. Excited light-flavor quarks (excited bottom quarks) are excluded up to a mass of 6.0 (3.8) TeV. Quantum black hole production is excluded for masses up to 7.5 (5.2) TeV in the ArkaniHamed-Dimopoulos-Dvali (Randall-Sundrum) model. These lower mass bounds are the most stringent to date among those obtained in the gamma +jet final state.