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LHCb Collaboration(Aaij, R. et al), Fernandez Casani, A., Jaimes Elles, S. J., Jashal, B. K., Libralon, S., Martinez-Vidal, F., et al. (2025). Measurement of CP asymmetry in Bs0 → Ds∓ K± decays. J. High Energy Phys., 03(3), 139–33pp.
Abstract: A measurement of the CP-violating parameters in B-s(0) -> D-s(-/+) K-+/- decays is reported, based on the analysis of proton-proton collision data collected by the LHCb experiment corresponding to an integrated luminosity of 6 fb(-1) at a centre-of-mass energy of 13TeV. The measured parameters are obtained with a decay-time dependent analysis yielding C-f = 0.791 +/- 0.061 +/- 0.022, A(f)(Delta Gamma) = -0.051 +/- 0.134 +/- 0.058, A((f) over bar)(Delta Gamma) = -0.303 +/- 0.125 +/- 0.055, S-f = -0.571 +/- 0.084 +/- 0.023 and S-(f) over bar = -0.503 +/- 0.084 +/- 0.025, where the first uncertainty is statistical and the second systematic. This corresponds to CP violation in the interference between mixing and decay of about 8.6 sigma. Together with the value of the B-s(0) mixing phase -2 beta s, these parameters are used to obtain a measurement of the CKM angle gamma equal to (74 +/- 12)degrees modulo 180 degrees, where the uncertainty contains both statistical and systematic contributions. This result is combined with the previous LHCb measurement in this channel using 3 fb(-1) resulting in a determination of gamma = (81(-11)(+12))degrees.
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LHCb Collaboration(Aaij, R. et al), Fernandez Casani, A., Jaimes Elles, S. J., Jashal, B. K., Libralon, S., Martinez-Vidal, F., et al. (2025). Search for charge-parity violation in semileptonically tagged D0 → K+ π- decays. J. High Energy Phys., 03(3), 149–30pp.
Abstract: An analysis of the flavour oscillations of the charmed neutral meson is presented. The ratio of D-0 -> K+ pi(-) and D-0 -> K- pi(+) decay rates is measured as a function of the decay time of the D-0 meson and compared with the charge-conjugated system to search for charge-parity violation. The meson flavour at production is double-tagged by the charges of the muon and pion in the preceding (B) over bar -> D*(2010)(+) mu(-) X and D*(2010)(+) -> D-0 pi(+) decays, respectively. These decays are selected from proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13TeV and corresponding to an integrated luminosity of 5.4 fb(-1). The flavour oscillation parameters, relating to the differences in mass and width of the mass eigenstates, are found to be y' = (5.8 +/- 1.6) x10(-3) and (x')(2) = (0.0 +/- 1.2) x10(-4). No evidence for charge-parity violation is seen either in the flavour oscillations or in the decay, where the direct charge-parity asymmetry is measured to be A(D) = (2.3 +/- 1.7)%.
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LHCb Collaboration(Aaij, R. et al), Fernandez Casani, A., Jaimes Elles, S. J., Jashal, B. K., Libralon, S., Martinez-Vidal, F., et al. (2025). Measurement of φ(1020) meson production in fixed-target pNe collisions at √sNN=68.5 GeV. J. High Energy Phys., 03(3), 151–21pp.
Abstract: The first measurement of phi(1020) meson production in fixed-target pNe collisions at root s(NN) = 68.5 GeV is presented. The phi(1020) mesons are reconstructed in their K+K- decay in a data sample consisting of proton collisions on neon nuclei at rest, corresponding to an integrated luminosity of 21.7 +/- 1.4 nb(-1), collected by the LHCb detector at CERN. The phi(1020) production cross-section in the centre-of-mass rapidity range of -1.8 < y* < 0 and transverse momentum range of 800 < p(T) < 6500MeV/ c is found to be sigma = 182.7 +/- 2.7 (stat.) +/- 14.1 (syst) μb/nucleon. A double-differential measurement of the cross-section is also provided in four regions of rapidity and six regions of transverse momentum of the phi(1020) meson and compared with the predictions from Pythia and EPOS4, which are found to underestimate the experimental values.
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Strumia, A., & Landini, G. (2025). Optical gravitational waves as signals of gravitationally-decaying particles. J. High Energy Phys., 04(4), 068–23pp.
Abstract: Long-lived heavy particles present during the big bang could have a decay channel opened by gravitons. Such decays can produce gravitational waves with large enough abundance to be detectable, and a peculiar narrow spectrum peaked today around optical frequencies. We identify which particles can decay in one or two gravitons. The maximal gravitational wave abundance arises from theories with extra hidden strong gauge dynamics, such as a confining pure-glue group. An interesting abundance also arises in theories with perturbative couplings. Future observation might shed light on early cosmology and allow some spectroscopy of sub-Planckian gravitationally-decaying particles, plausibly present in a variety of theories such as gauge unification, supersymmetry, extra dimensions, strings.
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Mollaebrahimi, A. et al: A., S. (2025). First observation of MNT isotope beams at the FRS Ion Catcher. Nucl. Phys. A, 1057, 123041–4pp.
Abstract: An exploratory experiment on Multi-Nucleon Transfer (MNT) reactions was successfully conducted at the FRS Ion Catcher setup at GSI. The experiment demonstrated the production of MNT-driven radioactive ion beams (RIBs) produced by decelerated relativistic beams. A beam of 238U ions was reacted with a 209Bi target at near-Coulomb barrier energies inside the specially modified Cryogenic Stopping Cell (CSC) for the production and thermalization of MNT products. These products were then identified using a Multiple-Reflection Time-Of-Flight Mass Spectrometer (MRTOF-MS). The observation of target-like MNT fragments along the A = 211 isobaric chain provided a proof-of-principle for future MNT studies with the FRS Ion Catcher setup.
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