ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., et al. (2023). Evidence of pair production of longitudinally polarised vector bosons and study of CP properties in ZZ → 4l events with the ATLAS detector at √s=13 TeV. J. High Energy Phys., 12(12), 107–48pp.
Abstract: A study of the polarisation and CP properties in ZZ production is presented. The used data set corresponds to an integrated luminosity of 140 fb(-1) of proton-proton collisions at a centre-of-mass energy of 13TeV recorded by the ATLAS detector at the Large Hadron Collider. The ZZ candidate events are reconstructed using two same-flavour opposite-charge electron or muon pairs. The production of two longitudinally polarised Z bosons is measured with a significance of 4.3 standard deviations, and its cross-section is measured in a fiducial phase space to be 2.45 +/- 0.60 fb, consistent with the next-to-leadingorder Standard Model prediction. The inclusive differential cross-section as a function of a CP-sensitive angular observable is also measured. The results are used to constrain anomalous CP-odd neutral triple gauge couplings.
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Gomez Dumm, D., Noguera, S., & Scoccola, N. N. (2023). Charged meson masses under strong magnetic fields: Gauge invariance and Schwinger phases. Phys. Rev. D, 108(1), 016012–29pp.
Abstract: We study the role of the Schwinger phase (SP) that appears in the propagator of a charged particle in the presence of a static and uniform magnetic field (B) over right arrow. We first note that this phase cannot be removed by a gauge transformation; far from this, we show that it plays an important role in the restoration of the symmetries of the system. Next, we analyze the effect of SPs in the one-loop corrections to charged pion and rho meson self-energies. To carry out this analysis we consider first a simple form for the meson-quark interactions, and then we study the pi(+) and rho(-) propagators within the Nambu-Jona-Lasinio model, performing a numerical analysis of the B dependence of meson lowest energy states. For both pi(+) and rho(-) mesons, we compare the numerical results arising from the full calculation-in which SPs are included in the propagators, and meson wave functions correspond to states of definite Landau quantum number-and those obtained within alternative schemes in which SPs are neglected (or somehow eliminated) and meson states are described by plane waves of definite four-momentum.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Search for direct CP violation in charged charmless B → PV decays. Phys. Rev. D, 108(1), 012013–13pp.
Abstract: Measurements of CP asymmetry in charmless B -> PV decays are presented, where P and V denote a pseudoscalar and a vector meson, respectively. Five different B -> PV decays from four final states, B-+/- -> pi(+/-)pi(+) pi(-), B-+/- -> K-+/-pi(+) pi(-), B-+/-->(KK+K-)-K-+/- and B-+/- -> pi(K+K-)-K-+/- are analyzed. The measurements are based on a method that does not require full amplitude analyses, and are performed using proton-proton collision data at a center-of-mass energy of 13 TeV collected by LHCb between 2015 and 2018, corresponding to an integrated luminosity of 5.9 fb(-1). In the pi(+) pi(-) P-wave, in the region dominated by the B-+/- -> rho(770)K-0(+/-) decay, a CP asymmetry of A(CP) = +0.150 +/- 0.019 +/- 0.011 is measured, where the first uncertainty is statistical and the second is systematic. This is the first observation of CP violation in this process. For the other four decay channels, in regions dominated by the B-+/- -> rho(770)(0)pi(+/-), B-+/- -> K(-)*(892)(0) pi(+/-), B-+/- -> K(-)* (892)K-+/- and B-+/- -> (sic)(1020) K-+/- decays, CP asymmetries in the P-wave compatible with zero are measured.
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Rinaldi, M., & Vento, V. (2023). Phase transition in the holographic hard-wall model. Phys. Rev. D, 108(11), 114020–10pp.
Abstract: A Hawking-Page phase transition between anti-de Sitter (AdS) thermal and AdS black hole was presented as a mechanism for explaining the QCD deconfinement phase transition within holographic models. In order to implement temperature dependence in the confined phase we use a hard-wall AdS/QCD model, where the geometry at low temperatures is described also by a black hole metric. We then investigate the temperature dependence of glueball states described as gravitons propagating in deformed background spaces. Finally, we use potential models to physically describe the implications of our study.
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T2K Collaboration(Abe, K. et al), Antonova, M., Cervera-Villanueva, A., Molina Bueno, L., & Novella, P. (2023). First measurement of muon neutrino charged-current interactions on hydrocarbon without pions in the final state using multiple detectors with correlated energy spectra at T2K. Phys. Rev. D, 108(11), 112009–32pp.
Abstract: This paper reports the first measurement of muon neutrino charged-current interactions without pions in the final state using multiple detectors with correlated energy spectra at T2K. The data was collected on hydrocarbon targets using the off-axis T2K near detector (ND280) and the on-axis T2K near detector (INGRID) with neutrino energy spectra peaked at 0.6 GeV and 1.1 GeV, respectively. The correlated neutrino flux presents an opportunity to reduce the impact of the flux uncertainty and to study the energy dependence of neutrino interactions. The extracted double-differential cross sections are compared to several Monte Carlo neutrino-nucleus interaction event generators showing the agreement between both detectors individually and with the correlated result.
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