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Sakai, S., Roca, L., & Oset, E. (2017). Charm-beauty meson bound states from B (B*)D(D*) and interaction B (B*)(D)over-bar((D)over-bar*). Phys. Rev. D, 96(5), 054023–9pp.
Abstract: We evaluate the s-wave interaction of pseudoscalar and vector mesons with both charm and beauty to investigate the possible existence of molecular BD, B* D, BD*, B* D*, B (D) over bar, B* (D) over bar, B (D) over bar*, or B* (D) over bar* meson states. The scattering amplitude is obtained implementing unitarity starting from a tree level potential accounting for the dominant vector meson exchange. The diagrams are evaluated using suitable extensions to the heavy flavor sector of the hidden gauge symmetry Lagrangians involving vector and pseudoscalar mesons, respecting heavy quark spin symmetry. We obtain bound states at energies above 7 GeV for BD (J(P) = 0(+)), B* D (1(+)), BD* (1(+)), and B* D* (0(+), 1(+,) 2(+)), all in isospin 0. For B (D) over bar (0(+)), B* (D) over bar (1(+)), B (D) over bar* (1(+)), and B* (D) over bar* (0(+), 1(+), 2(+)) we also find similar bound states in I = 0, but much less bound, which would correspond to exotic meson states with _ (b) over bar and (c) over bar quarks, and for the I = 1 we find a repulsive interaction. We also evaluate the scattering lengths in all cases, which can be tested in current investigations of lattice QCD.
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Sakai, S., Oset, E., & Liang, W. H. (2017). Abnormal isospin violation and a(0) – f(0) mixing in the D-s(+) -> pi(+) pi(0)a(0)(980)(f(0)(980)) reactions. Phys. Rev. D, 96(7), 074025–11pp.
Abstract: We have chosen the reactions D-s(+) -> pi(+) pi(0)a(0)(980)(f(0)(980)) investigating the isospin violating channel D-s(+) -> pi+ pi(0)f(0)(980). The reaction was chosen because by varying the pi(0)a(0)(980)(f(0)(980)) invariant mass one goes through the peak of a triangle singularity emerging from D-s(+) -> pi(K) over bar *K, followed by (K) over bar* -> (K) over bar pi(0) and the further merging of K (K) over bar to produce the a(0)(980) or f(0)(980). We found that the amount of isospin violation had its peak precisely at the value of the pi(0)a(0)(980)(f(0)(980)) invariant mass where the singularity has its maximum, stressing the role of the triangle singularities as a factor to enhance the mixing of the f(0)(980) and a(0)(980) resonances. We calculate absolute rates for the reactions and show that they are within present measurable range. The measurement of these reactions would bring further information into the role of triangle singularities in isospin violation and the a(0) – f(0) mixing, in particular, and shed further light into the nature of the low energy scalar mesons.
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Sakai, S., Hosaka, A., & Nagahiro, H. (2017). Effect of the final state interaction of eta ' N on the eta ' photoproduction off the nucleon. Phys. Rev. C, 95(4), 045206–9pp.
Abstract: We investigate the eta' photoproduction off the nucleon with a particular interest in the effect of the final-state interaction (FSI) of the eta' meson and nucleon (eta' N) based on the three-flavor linear sigma model. We find an enhancement in the cross section of the eta' photoproduction near the eta' N-threshold energy owing to the eta' N FSI. With the eta' meson at forward angles, the energy dependence near the eta' N threshold is well reproduced with the eta' N FSI. The cross section at backward angles can also be a good probe to investigate the strength of the eta' N interaction.
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Rubio, B., Gelletly, W., Algora, A., Nacher, E., & Tain, J. L. (2017). Beta decay studies with total absorption spectroscopy and the Lucrecia spectrometer at ISOLDE. J. Phys. G, 44(8), 084004–25pp.
Abstract: Here we present the experimental activities carried out at ISOLDE with the total absorption spectrometer Lucrecia, a large 4 pi scintillator detector designed to absorb a full gamma cascade following beta decay. This spectrometer is designed to measure beta-feeding to excited states without the systematic error called Pandemonium. The set up allows the measurement of decays of very short half life. Experimental results from several campaigns, that focus on the determination of the shapes of beta-decaying nuclei by measuring their beta decay strength distributions as a function of excitation energy in the daughter nucleus, are presented.
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Rout, J., Masud, M., & Mehta, P. (2017). Can we probe intrinsic CP and T violations and nonunitarity at long baseline accelerator experiments? Phys. Rev. D, 95(7), 075035–23pp.
Abstract: One of the fundamental parameters entering the neutrino oscillation framework is the leptonic CP phase delta(13), and its measurement is an important goal of the planned long baseline experiments. It should be noted that ordinary matter effects complicate the determination of this parameter, and there are studies in the literature that deal with separation of intrinsic vs extrinsic CP violation. It is important to investigate the consequences of new physics effects that can not only hamper the measurement of delta(13) but also impact the consequences of discrete symmetries such as CP, T, and unitarity in different oscillation channels. In the present work, we explore these discrete symmetries and implications on unitarity in the presence of two new physics scenarios (nonstandard interaction in propagation and the presence of sterile neutrinos) that serve as good examples of going beyond the standard scenario in different directions. We uncover the impact of new physics scenarios on disentangling intrinsic and extrinsic CP violation.
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