30 research outputs found

    SR-GAN for SR-gamma: photon super resolution at collider experiments

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    We study single-image super-resolution algorithms for photons at collider experiments based on generative adversarial networks. We treat the energy depositions of simulated electromagnetic showers of photons and neutral-pion decays in a toy electromagnetic calorimeter as 2D images and we train super-resolution networks to generate images with an artificially increased resolution by a factor of four in each dimension. The generated images are able to reproduce features of the electromagnetic showers that are not obvious from the images at nominal resolution. Using the artificially-enhanced images for the reconstruction of shower-shape variables and of the position of the shower center results in significant improvements. We additionally investigate the utilization of the generated images as a pre-processing step for deep-learning photon-identification algorithms and observe improvements in the case of low training statistics.Comment: 24 pages, 13 figure

    Elliptic anisotropy measurement of the f0_0(980) hadron in proton-lead collisions and evidence for its quark-antiquark composition

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    International audienceDespite the f0_0(980) hadron having been discovered half a century ago, the question about its quark content has not been settled: it might be an ordinary quark-antiquark (qqňČ\mathrm{q\bar{q}}) meson, a tetraquark (qqňČqqňČ\mathrm{q\bar{q}q\bar{q}}) exotic state, a kaon-antikaon (KKňČ\mathrm{K\bar{K}}) molecule, or a quark-antiquark-gluon (qqňČg\mathrm{q\bar{q}g}) hybrid. This paper reports strong evidence that the f0_0(980) state is an ordinary qqňČ\mathrm{q\bar{q}} meson, inferred from the scaling of elliptic anisotropies (v2v_2) with the number of constituent quarks (nqn_\mathrm{q}), as empirically established using conventional hadrons in relativistic heavy ion collisions. The f0_0(980) state is reconstructed via its dominant decay channel f0_0(980) ‚Üí\toŌÄ+ŌÄ‚ąí\pi^+\pi^-, in proton-lead collisions recorded by the CMS experiment at the LHC, and its v2v_2 is measured as a function of transverse momentum (pTp_\mathrm{T}). It is found that the nqn_q = 2 (qqňČ\mathrm{q\bar{q}} state) hypothesis is favored over nqn_q = 4 (qqňČqqňČ\mathrm{q\bar{q}q\bar{q}} or KKňČ\mathrm{K\bar{K}} states) by 7.7, 6.3, or 3.1 standard deviations in the pTp_\mathrm{T}<\lt 10, 8, or 6 GeV/cc ranges, respectively, and over nqn_\mathrm{q} = 3 (qqňČg\mathrm{q\bar{q}g} hybrid state) by 3.5 standard deviations in the pTp_\mathrm{T}<\lt 8 GeV/cc range. This result represents the first determination of the quark content of the f0_0(980) state, made possible by using a novel approach, and paves the way for similar studies of other exotic hadron candidates

    Elliptic anisotropy measurement of the f0_0(980) hadron in proton-lead collisions and evidence for its quark-antiquark composition