ATLAS Collaboration(Aad, G. et al), Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., Cabrera Urban, S., et al. (2024). Search for leptoquark pair production decaying into te−t¯e+ or tμ−t¯μ+ in multi-lepton final states in pp collisions at √s=13 TeV with the ATLAS detector. Eur. Phys. J. C, 84(8), 818–40pp.
Abstract: A search for leptoquark pair production decaying into te(-)(t) over bare(+) or t mu(-)(t) over bar mu(+) in final states with multiple leptons is presented. The search is based on a dataset of pp collisions at root s = 13TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb(-1). Four signal regions, with the requirement of at least three light leptons (electron or muon) and at least two jets out of which at least one jet is identified as coming from a b-hadron, are considered based on the number of leptons of a given flavour. The main background processes are estimated using dedicated control regions in a simultaneous fit with the signal regions to data. No excess above the Standard Model background prediction is observed and 95% confidence level limits on the production cross section times branching ratio are derived as a function of the leptoquark mass. Under the assumption of exclusive decays into te(-) (t mu(-)), the corresponding lower limit on the scalar mixed-generation leptoquark mass m(LQmixd) is at 1.58 (1.59) TeV and on the vector leptoquark mass m((U) over tilde1) at 1.67 (1.67) TeV in the minimal coupling scenario and at 1.95 (1.95) TeV in the Yang-Mills scenario.
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Aguilar, A. C., Ferreira, M. N., Oliveira, B. M., Papavassiliou, J., & Teixeira, G. L. (2024). Infrared properties of the quark-gluon vertex in general kinematics. Eur. Phys. J. C, 84(11), 1231–21pp.
Abstract: In the present work we determine the eight form factors of the transversely-projected quark-gluon vertex in general kinematics, in the context of Landau-gauge QCD with two degenerate light dynamical quarks. The study is based on the set of Schwinger-Dyson equations that govern the vertex form factors, derived within the formalism of the three-particle-irreducible (3PI) effective action. The analysis is performed by employing lattice data for the main ingredients, such as gluon and quark propagators, and three-gluon vertex. The numerical treatment is simplified by decoupling the system of integral equations: the classical form factor is determined from a single non-linear equation involving only itself, while the remaining ones are subsequently computed through simple integrations. The form factors are obtained for arbitrary values of space-like momenta, and their angular dependence is examined in detail. A clear hierarchy is established at the level of the corresponding dimensionless effective couplings, in agreement with results of earlier studies. Furthermore, the classical form factor is found to be in excellent agreement with recent unquenched lattice data in the soft-gluon configuration, while the two non-classical dressings depart substantially from the lattice results. Finally, the accurate implementation of multiplicative renormalizability is confirmed, and the transition from Minkoswski to Euclidean space is elucidated.
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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. (2024). Observation of Ξb0→ Ξc + Ds- and Ξb0 c D- s decays. Eur. Phys. J. C, 84(3), 237–17pp.
Abstract: The Ξ0b→Ξ+cD−s and Ξ−b→Ξ0cD−s decays are observed for the first time using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of s√=13TeV, corresponding to an integrated luminosity of 5.1fb−1. The relative branching fractions times the beauty-baryon production cross-sections are measured to be (formula), where the first uncertainties are statistical, the second systematic, and the third due to the uncertainties on the branching fractions of relevant charm-baryon decays. The masses of Ξ0b and Ξ−b baryons are measured to be mΞ0b=5791.12±0.60±0.45±0.24MeV/c2 and mΞ−b=5797.02±0.63±0.49±0.29MeV/c2, where the uncertainties are statistical, systematic, and those due to charm-hadron masses, respectively.
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Unbehaun, T. et al(C. T. A. C. and K. M. 3N. T. C.), Alves Garre, S., Calvo, D., Carretero, V., Cecchini, V., Garcia Soto, A., et al. (2024). Prospects for combined analyses of hadronic emission from γ-ray sources in the Milky Way with CTA and KM3NeT. Eur. Phys. J. C, 84(2), 112–19pp.
Abstract: The Cherenkov Telescope Array and the KM3NeT neutrino telescopes are major upcoming facilities in the fields of gamma-ray and neutrino astronomy, respectively. Possible simultaneous production of gamma rays and neutrinos in astrophysical accelerators of cosmic-ray nuclei motivates a combination of their data. We assess the potential of a combined analysis of CTA and KM3NeT data to determine the contribution of hadronic emission processes in known Galactic gamma-ray emitters, comparing this result to the cases of two separate analyses. In doing so, we demonstrate the capability of GAMMAPY, an open-source software package for the analysis of gamma-ray data, to also process data from neutrino telescopes. For a selection of prototypical gamma-ray sources within our Galaxy, we obtain models for primary proton and electron spectra in the hadronic and leptonic emission scenario, respectively, by fitting published gamma-ray spectra. Using these models and instrument response functions for both detectors, we employ the GAMMAPY package to generate pseudo data sets, where we assume 200 h of CTA observations and 10 years of KM3NeT detector operation. We then apply a three-dimensional binned likelihood analysis to these data sets, separately for each instrument and jointly for both. We find that the largest benefit of the combined analysis lies in the possibility of a consistent modelling of the gamma-ray and neutrino emission. Assuming a purely leptonic scenario as input, we obtain, for the most favourable source, an average expected 68% credible interval that constrains the contribution of hadronic processes to the observed gamma-ray emission to below 15%.
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Zhang, S. C., Duan, M. Y., Lyu, W. T., Wang, G. Y., Zhu, J. Y., & Wang, E. (2024). Explore the properties of Λ(1670) in the Cabibbo-favored process Λc+ → p K- π+. Eur. Phys. J. C, 84(12), 1253–8pp.
Abstract: Recently, the Belle and LHCb Collaborations have measured the Lambda c+-> pK-pi+ invariant mass distribution, which shows a clear cusp structure around the eta Lambda threshold. In this work, we have analyzed this process by considering the triangle mechanism and the S-wave pseudoscalar meson-octet baryon interactions within the chiral unitary approach, which dynamically generates the Lambda(1670). Our results are in good agreement with the Belle measurements, which implies that the cusp structure around eta Lambda threshold could be associated with the Lambda(1670) with the molecular nature.
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Song, J., Liang, W. H., Xiao, C. W., Dias, J. M., & Oset, E. (2024). Testing the molecular nature of the Ω (2012) with the ψ (3770) → (Ω)over-bar(K)over-barΞ and ψ (3770) → (Ω)over-bar(K)over-barΞ* (1530) ((Ω)over-bar(K)over-barπΞ) reactions. Eur. Phys. J. C, 84(12), 1311–7pp.
Abstract: We report on the reactions psi(3770) -> (Omega) over bar+(K) over bar Xi and psi(3770) -> (Omega) over bar (+)(K) over bar Xi*(1530) (Xi* (1530) -> pi Xi), and calculate the mass distributions d Gamma/dM(inv)((K) over bar Xi) and d Gamma/dM(inv)(K Xi*), respectively. We obtain clear peaks corresponding to the Omega(2012). From the decay of psi(3770) -> (Omega) over bar (+)(K) over bar Xi*, we also get a second, broader, peak around 2035MeV, which comes from the Omega(2012) decay to (K) over bar Xi*. This second peak is closely tied to the molecular picture of the Omega(2012) with the (K) over bar Xi* (1530) and eta Omega components. Its observation would provide a boost to the molecular picture of the Omega (2012).
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Lyu, W. T., Duan, M. Y., Xiao, C. W., Wang, E., & Oset, E. (2024). Possible signal of an exotic I=1, J=2 state in the B → D*- D+ K+ reaction. Eur. Phys. J. C, 84(12), 1302–6pp.
Abstract: We study the B+ -> D*(-) D+ K+ reaction, showing that a peak in the D+ K+ mass distribution around 2834 MeV reported by LHCb could be associated with a theoretical exotic state with that mass, a width of 19 MeV and J(P) = 2(+), stemming from the interaction of the D*K+*(+) and D-s*(+) rho(+) channels, which is a partner of the 0(+) T-c (s) over bar (2900). We show that the data is compatible with this assumption, but also see that the mass distribution itself cannot discriminate between the spins J = 0, 1, 2 of the state. Then we evaluate the momenta of the angular mass distribution and show that they are very different for each of the spin assumptions, and that the momenta coming from interference terms have larger strength at the resonant energy than the peaks seen in the angular integrated mass distribution. We make a call for the experimental determination of these magnitudes, which has already been used by the LHCb in related decay reactions.
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Andrade, I., Bazeia, D., Marques, M. A., Menezes, R., & Olmo, G. J. (2025). Analytical solutions for Maxwell-scalar system on radially symmetric spacetimes. Eur. Phys. J. C, 85(1), 27–15pp.
Abstract: We investigate Maxwell-scalar models on radially symmetric spacetimes in which the gauge and scalar fields are coupled via the electric permittivity. We find the conditions that allow for the presence of minimum energy configurations. In this formalism, the charge density must be written exclusively in terms of the components of the metric tensor and the scalar field is governed by first-order equations. We also find a manner to map the aforementioned equation into the corresponding one associated to kinks in (1, 1) spacetime dimensions, so we get analytical solutions for three specific spacetimes. We then calculate the energy density and show that the energy is finite. The stability of the solutions against contractions and dilations, following Derrick's argument, and around small fluctuations in the fields is also investigated. In this direction, we show that the solutions obeying the first-order framework are stable.
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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Aparisi Pozo, J. A., Bailey, A. J., Bouchhar, N., et al. (2024). Precise measurements of W- and Z-boson transverse momentum spectra with the ATLAS detector using pp collisions at √s=5.02 TeV and 13 TeV. Eur. Phys. J. C, 84(10), 1126–60pp.
Abstract: This paper describes measurements of the transverse momentum spectra of W and Z bosons produced in proton-proton collisions at centre-of-mass energies of root s = 5.02 TeV and root s = 13 TeV with the ATLAS experiment at the Large Hadron Collider. Measurements are performed in the electron and muon channels, W -> l nu and Z -> ll (l = e or mu), and for W events further separated by charge. The data were collected in 2017 and 2018, in dedicated runs with reduced instantaneous luminosity, and correspond to 255 and 338 pb(-1) at root s = 5.02 TeV and 13 TeV, respectively. These conditions optimise the reconstruction of the W-boson transverse momentum. The distributions observed in the electron and muon channels are unfolded, combined, and compared to QCD calculations based on parton shower Monte Carlo event generators and analytical resummation. The description of the transverse momentum distributions by Monte Carlo event generators is imperfect and shows significant differences largely common to W-, W+ and Z production. The agreement is better at root s = 5.02 TeV, especvially for predictions that were tuned to Z production data at root s = 7 TeV. Higher-order, resummed predictions based on DYTURBO generally match the data best across the spectra. Distribution ratios are also presented and test the understanding of differences between the production processes.
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ATLAS Collaboration(Aad, G. et al), Aikot, A., Amos, K. R., Bouchhar, N., Cabrera Urban, S., Cantero, J., et al. (2024). Constraints on simplified dark matter models involving an s-channel mediator with the ATLAS detector in pp collisions at √s=13 TeV. Eur. Phys. J. C, 84(10), 1102–37pp.
Abstract: This paper reports a summary of searches for a fermionic dark matter candidate in the context of theoretical models characterised by a mediator particle exchange in the s-channel. The data sample considered consists of pp collisions delivered by the Large Hadron Collider during its Run 2 at a centre-of-mass energy of root s = 13 TeV and recorded by the ATLAS detector, corresponding to up to 140 fb(-1). The interpretations of the results are based on simplified models where the new mediator particles can be spin-0, with scalar or pseudo-scalar couplings to fermions, or spin-1, with vector or axial-vector couplings to fermions. Exclusion limits are obtained from various searches characterised by final states with resonant production of Standard Model particles, or production of Standard Model particles in association with large missing transverse momentum.
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