| |
Casale, P. R., Amaro, J. E., Belocchi, V., Barbaro, M. B., De Pace, A., & Martini, M. (2025). Interference between meson exchange and one-body currents in quasielastic electron scattering. Phys. Rev. C, 112(2), 024603–29pp.
Abstract: In this work, we present a detailed analysis of the interference between meson exchange currents (MEC) and one-body currents in quasielastic electron scattering, with a focus on the sign of this interference in the transverse response for one-particle emission. We prove that the interference of both the Delta and pion-in-flight currents with the one-body current is negative, leading to a partial cancellation with the seagull current. This is mathematically demonstrated within the framework of the Fermi gas model. By comparing these interferences across various independent particle models, both relativistic and nonrelativistic, our results indicate that all studied models display the same behavior.
|
|
Mantani, L., & Sanz, V. (2025). Probing the flavour-blind SMEFT: EFT validity and the interplay of energy scales. J. High Energy Phys., 06(6), 147–31pp.
Abstract: The Standard Model Effective Field Theory (SMEFT) offers a systematic approach to study potential deviations from the Standard Model (SM) through higher-dimensional operators that encapsulate new physics effects. In this work, we analyze flavour-blind SMEFT contributions to flavour observables and assess their interplay with high-energy measurements from LEP and LHC. We perform global fits combining LEP precision data, flavour observables from rare B-meson decays, and LHC diboson measurements, revealing how the inclusion of different datasets breaks parameter degeneracies and enhances the sensitivity to SMEFT coefficients. Our study demonstrates that low-energy flavour observables provide reliable constraints even in flavour-blind scenarios, while high-energy measurements can be subject to EFT validity concerns due to kinematic growth. We investigate the impact of renormalization group evolution (RGE) and operator mixing across energy scales, highlighting the complementary nature of low- and high-energy datasets. The results emphasize the importance of flavour observables as robust probes of new physics and underline the necessity of global fits to avoid potential biases from limited datasets. Finally, we discuss the implications of our findings for the interpretation of global SMEFT analyses based on high-energy collider data, comparing UV models that contribute to SMEFT at tree- and loop-level.
|
|
LHCb Collaboration(Aaij, R. et al), Fernandez Casani, A., Jaimes Elles, S. J., Jashal, B. K., Libralon, S., Martinez-Vidal, F., et al. (2025). Angular analysis of B0 → K*0 e+ e- decays. J. High Energy Phys., 06(6), 140–53pp.
Abstract: An angular analysis of B0 -> K*0e+e- decays is presented using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb-1. The analysis is performed in the region of the dilepton invariant mass squared of 1.1-6.0 GeV2/c4. In addition, a test of lepton flavour universality is performed by comparing the obtained angular observables with those measured in B0 -> K*0 mu+mu- decays. In general, the angular observables are found to be consistent with the Standard Model expectations as well as with global analyses of other b -> s & ell;+& ell;- processes, where & ell; is either a muon or an electron. No sign of lepton-flavour-violating effects is observed.
|
|
LHCb Collaboration(Aaij, R. et al), Fernandez Casani, A., Jaimes Elles, S. J., Jashal, B. K., Libralon, S., Martinez-Vidal, F., et al. (2025). Test of Lepton Flavor Universality with Bs0 → φl+ l- Decays. Phys. Rev. Lett., 134(12), 121803–15pp.
Abstract: Lepton flavor universality in rare b -> s transitions is tested for the first time using B-s(0) meson decays. The measurements are performed using pp collision data collected by the LHCb experiment between 2011 and 2018, corresponding to a total integrated luminosity of 9 fb(-1). Branching fraction ratios between the B-s(0) -> phi e(+) e(-) and B-s(0) -> phi mu(+) mu(-) decays are measured in three regions of dilepton mass squared, q(2), with 0.1 < q(2) < 1.1, 1.1 < q(2) < 6.0, and 15 < q(2) < 19 GeV2/c(4). The results agree with the standard model expectation of lepton flavor universality.
|
|
Zhuang, Z. J., Molina, R., Lu, J. X., & Geng, L. S. (2025). Pole trajectories of the A 1405 help establish its dynamical nature. Sci. Bull., 70(12), 1953–1961.
Abstract: The A 1405 has been one of the most controversial exotic baryons. If the A 1405 possesses a two-pole molecular structure, these poles are expected to evolve differently towards the SU(3) limit. From an analysis of a recent LQCD simulation on the pi Sigma -(K) over barN scattering for I 0 and the study of the quark mass dependence of the octet baryon masses, we determine for the first time the trajectories of these poles towards the symmetric point over the Tr[M] = C trajectory accurately. At m(pi) similar or equal to 200 MeV, our results are consistent with the lattice simulations, and the extrapolations to the physical point, based on the NLO chiral Lagrangians, agree well with existing experimental analyses. We predict qualitatively similar trajectories at LO and up to NLO, consistent with the LO interaction's dominance. At the SU(3) symmetric point of this trajectory, both poles are on the physical sheet, and the lower pole is located at E(1) =1573(6)(6) MeV, becoming a SU(3) singlet, while the higher pole at E ((8a)) = 1589 (7) (5) MeV couples to the octet representation. Moreover, we make predictions in I = 1 for the E resonance. We find a resonance pole that evolves into a bound state around m(pi) = 415 MeV in this sector. The results presented here are crucial to shed light on the molecular nature of exotic strange baryon resonances and can be tested in future LQCD simulations.
|
|
|
