Huang, G. Y., Lindner, M., Martinez-Mirave, P., & Sen, M. (2022). Cosmology-friendly time-varying neutrino masses via the sterile neutrino portal. Phys. Rev. D, 106(3), 033004–18pp.
Abstract: We investigate a consistent scenario of time-varying neutrino masses, and discuss its impact on cosmology, beta decay, and neutrino oscillation experiments. Such time-varying masses are assumed to be generated by the coupling between a sterile neutrino and an ultralight scalar field, which in turn affects the light neutrinos by mixing. We demonstrate how various cosmological bounds, such as those coming from big bang nucleosynthesis, the cosmic microwave background, as well as large scale structures, can be evaded in this model. This scenario can be further constrained using multiple terrestrial experiments. In particular, for beta-decay experiments like KATRIN, nontrivial distortions to the electron spectrum can be induced, even when time-variation is fast and it gets averaged. Furthermore, the presence of time-varying masses of sterile neutrinos will alter the interpretation of light sterile neutrino parameter space in the context of the reactor and gallium anomalies. In addition, we also study the impact of such time-varying neutrino masses on results from the BEST collaboration, which have recently strengthened the gallium anomaly. If confirmed, we find that the time-varying neutrino mass hypothesis could give a better fit to the recent BEST data.
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Hansen, M. T., Romero-Lopez, F., & Sharpe, S. R. (2021). Decay amplitudes to three hadrons from finite-volume matrix elements. J. High Energy Phys., 04(4), 113–44pp.
Abstract: We derive relations between finite-volume matrix elements and infinite-volume decay amplitudes, for processes with three spinless, degenerate and either identical or non-identical particles in the final state. This generalizes the Lellouch-Luscher relation for two-particle decays and provides a strategy for extracting three-hadron decay amplitudes using lattice QCD. Unlike for two particles, even in the simplest approximation, one must solve integral equations to obtain the physical decay amplitude, a consequence of the nontrivial finite-state interactions. We first derive the result in a simplified theory with three identical particles, and then present the generalizations needed to study phenomenologically relevant three-pion decays. The specific processes we discuss are the CP-violating K -> 3 pi weak decay, the isospin-breaking eta -> 3 pi QCD transition, and the electromagnetic gamma (*) -> 3 pi amplitudes that enter the calculation of the hadronic vacuum polarization contribution to muonic g – 2.
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Albaladejo, M., Nielsen, M., & Oset, E. (2015). Ds0*(+/-)(2317) and K D scattering from Bs(0) decay. Phys. Lett. B, 746, 305–310.
Abstract: We study the (B) over bar (0)(s) -> D-s(-)(KD)(+) weak decay, and look at the KD invariant mass distribution, for which we use recent lattice QCD results for the KDinteraction from where the D-s0*(2317) resonance appears as a KD bound state. Since there are not yet experimental data on this reaction, in a second step we propose an analysis method to obtain information on the D-s0* (2317) resonance from the future experimental KD mass distribution in this decay. For this purpose, we generate synthetic data taking a few points from our theoretical distribution, to which we add a 5% or 10% error. With this analysis method, we prove that one can obtain from these “data” the existence of a bound KD state, the KD scattering length and effective range, and most importantly, the KD probability in the wave function of the bound state obtained, which was found to be largely dominant in lattice QCD studies. This means that one can obtain information on the nature of the D-s0*(+) (2317) resonance from the implementation of this experiment, in the line of finding the structure of resonances, which is one of the main aims in hadron spectroscopy.
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Liddick, S. N., Spyrou, A., Crider, B. P., Naqvi, F., Larsen, A. C., Guttormsen, M., et al. (2016). Experimental Neutron Capture Rate Constraint Far from Stability. Phys. Rev. Lett., 116(24), 242502–6pp.
Abstract: Nuclear reactions where an exotic nucleus captures a neutron are critical for a wide variety of applications, from energy production and national security, to astrophysical processes, and nucleosynthesis. Neutron capture rates are well constrained near stable isotopes where experimental data are available; however, moving far from the valley of stability, uncertainties grow by orders of magnitude. This is due to the complete lack of experimental constraints, as the direct measurement of a neutron-capture reaction on a short-lived nucleus is extremely challenging. Here, we report on the first experimental extraction of a neutron capture reaction rate on Ni-69, a nucleus that is five neutrons away from the last stable isotope of Ni. The implications of this measurement on nucleosynthesis around mass 70 are discussed, and the impact of similar future measurements on the understanding of the origin of the heavy elements in the cosmos is presented.
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Martinez Torres, A., Khemchandani, K. P., Nielsen, M., Navarra, F. S., & Oset, E. (2013). Exploring the D* rho system within QCD sum rules. Phys. Rev. D, 88(7), 074033–14pp.
Abstract: We present a study of the D* rho system made by using the method of QCD sum rules to determine the mass of possible resonances generated in the same system. Using isospin and spin projectors, we investigate the different configurations and obtain evidences for three D* mesons with isospin I = 1/2, spin S = 0, 1, 2 and with masses 2500 +/- 67, 2523 +/- 60, and 2439 +/- 119 MeV, respectively. The last state can be associated with D-2*(2460) ( spin 2) listed by the Particle Data Group, while one of the first two might be related to D* (2640), with unknown spin parity. In the case of I = 3/2 we also find evidences of three states with spin 0, 1, and 2, respectively, with masses 2467 +/- 82, 2420 +/- 128, and 2550 +/- 56 MeV. The results for the sector I = 1/2 and S 0, 1, 2, are intriguingly similar to a previous study of the D* rho system based on effective field theories, supporting in this way a molecular picture for the resonances D* (2640) and D-2* (2460), while the results for I = 3/2 hint towards the existence of exotic mesons since a multiquark configuration is required to get the quantum numbers of the states found.
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