2,638 research outputs found

    Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

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    The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum

    On Perceived AV Synchronization in 360° Multimedia

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    Media synchronization and, in particular, audiovisual (AV) synchronization, plays a pivotal role in multimedia systems, significantly impacting the quality of experience (QoE) perceived by users. What is intriguing is that despite the growing prevalence of multimedia content consumption in 360° environments, the issue of perceived AV synchronization remains relatively unexplored. To tackle this challenge, we present the results of a user study that assessed the influence of AV skews on QoE and the feeling of presence within 360° multimedia content. By examining the various effects of AV skews on the user experience, we gain valuable insights into the factors that shape QoE and presence in such immersive settings. These findings have the potential to improve the design and development of more engaging and effective multimedia content, ensuring a seamless and enjoyable experience for users in 360° contexts.This work was supported by the CAPES, Brazil—Finance Code 88887.570688/2020-00 and 88881.689984/2022-01; CNPQ, Brazil—Finance Code 307718/2020-4; and FAPES, Brazil—Finance Code 2021-GL60J
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