Abstract: We have done a theoretical study of the gamma d -> pi(0)eta d reaction starting with a realistic model for the gamma N -> pi(0)eta N reaction that reproduces cross sections and polarization observables at low energies and involves the gamma N -> Delta(1700) -> eta Delta(1232) -> eta pi N-0 process. For the coherent reaction in the deuteron we considered the impulse approximation together with the rescattering of the pions and the eta on a different nucleon than the one where they are produced. We found this second mechanism very important since it helps share between two nucleons the otherwise large momentum transfer of the reaction. Other contributions to the gamma d -> pi(0)eta d reaction, involving the gamma N -> pi(+/-)pi N-0' process, followed by the rescattering of the pi(+/-) with another nucleon to give eta and a nucleon, have also been included. We find a natural explanation, tied to the dynamics of our model, for the shift of the eta-d mass distribution to lower invariant masses, and of the pi(0)-d mass distribution to larger invariant masses, compared to a phase space calculation. We also study theoretical uncertainties related to the large momenta of the deuteron wave function involved in the process as well as to the couplings present in the model. Striking differences are found with the experimental angular distribution and further theoretical investigations might be necessary.

Abstract: Excited states in the mirror nuclei P-31 and S-31 were populated in the 1p and 1n exit channels of the reaction Ne-20 + C-12, at a beam energy of 33 MeV. The Ne-20 beam was delivered for the first time by the Piave-Alpi accelerator of the Laboratori Nazionali di Legnaro. Angular correlations of coincident gamma-rays and Doppler-shift attenuation lifetime measurements were performed using the multi-detector array GASP in conjunction with the EUCLIDES charged particle detector. In the observed B(E1) strengths, the isoscalar component, amounting to 24% of the isovector one, provides strong evidence for breaking of the isospin symmetry in the A = 31 mass region. Self-consistent beyond mean field calculations using Equation of Motion method based on a chiral potential and including two- and three-body forces reproduce well the experimental B(E1) strengths, reinforcing our conclusion. Coherent mixing from higher-lying states involving the Giant Isovector Monopole Resonance accounts well for the effect observed. The breaking of the isospin symmetry originates from the violation of the charge symmetry of the two- and three-body parts of the potential, only related to the Coulomb interaction.

Abstract: By looking at the pseudoscalar-vector meson spectra in the (B) over bar -> J/psi rho(K) over bar and (B) over bar -> J/psi(K) over bar*pi weak decays, we theoretically investigate the double-pole structure of the K-1 (1270) resonance by using the chiral unitary approach to account for the final-state interactions between the pseudoscalar (P) and vector (V) mesons. The K-1 (1270) resonance is dynamically generated through these interactions in coupled channels and influences the shape of the invariant mass distributions under consideration. We show how these shapes are affected by the K-1 (1270) double-pole structure to confront the results from our model with future experiments that might investigate the PV spectra in these decays.

Abstract: Many scenarios of new physics predict the existence of neutrino nonstandard interactions, new vector contact interactions between neutrinos, and first generation fermions beyond the Standard Model. We obtain model-independent constraints on the Standard Model effective field theory at high energies from bounds on neutrino nonstandard interactions derived at low energies. Our analysis explores a large set of new physics scenarios and includes full one-loop running effects below and above the electroweak scale. Our results show that neutrino nonstandard interactions already push the scale of new physics beyond the TeV. We also conclude that bounds derived by other experimental probes, in particular by low-energy precision measurements and by charged lepton flavor violation searches, are generally more stringent. Our study constitutes a first step toward the systematization of phenomenological analyses to evaluate the impact of neutrino nonstandard interactions for new physics scenarios at high energies.

Abstract: The neutron-induced fission cross sections of Th-232 and U-233 were measured relative to U-235 in a wide neutron energy range up to 1 GeV (and from fission threshold in the case of Th-232, and from 0.7 eV in case of U-233), using the white-spectrum neutron source at the CERN Neutron Time-of-Flight (nTOF) facility. Parallel plate avalanche counters (PPACs) were used, installed at the Experimental Area 1 (EAR1), which is located at 185 m from the neutron spallation target. The anisotropic emission of fission fragments were taken into account in the detection efficiency by using, in the case of U-233, previous results available in EXFOR, whereas in the case of Th-232 these data were obtained from our measurement, using PPACs and targets tilted 45 degrees with respect to the neutron beam direction. Finally, the obtained results are compared with past measurements and major evaluated nuclear data libraries. Calculations using the high-energy reaction models INCL++ and ABLA07 were performed and some of their parameters were modified to reproduce the experimental results. At high energies, where no other neutron data exist, our results are compared with experimental data on proton-induced fission. Moreover, the dependence of the fission cross section at 1 GeV with the fissility parameter of the target nucleus is studied by combining those ( p, f) data with our (n, f) data on Th-232 and U-233 and on other isotopes studied earlier at nTOF using the same experimental setup.