T2K Collaboration(Abe, K. et al), Cervera-Villanueva, A., Escudero, L., Izmaylov, A., Sorel, M., & Stamoulis, P. (2015). Measurement of the electron neutrino charged-current interaction rate on water with the T2K ND280 pi(0) detector. Phys. Rev. D, 91(11), 112010–11pp.
Abstract: This paper presents a measurement of the charged current interaction rate of the electron neutrino beam component of the beam above 1.5 GeV using the large fiducial mass of the T2K pi(0) detector. The predominant portion of the v(e) flux (similar to 85%) at these energies comes from kaon decays. The measured ratio of the observed beam interaction rate to the predicted rate in the detector with water targets filled is 0.89 +/- 0.08(stat) +/- 0.11(sys), and with the water targets emptied is 0.90 +/- 0.09(stat) +/- 0.13 (sys). The ratio obtained for the interactions on water only from an event subtraction method is 0.87 +/- 0.33(stat) +/- 0.21(sys). This is the first measurement of the interaction rate of electron neutrinos on water, which is particularly of interest to experiments with water Cherenkov detectors.
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T2K Collaboration(Abe, K. et al), Cervera-Villanueva, A., Escudero, L., Izmaylov, A., Sorel, M., & Stamoulis, P. (2015). Neutrino oscillation physics potential of the T2K experiment. Prog. Theor. Exp. Phys., (4), 043C01–36pp.
Abstract: The observation of the recent electron neutrino appearance in a muon neutrino beam and the high-precision measurement of the mixing angle theta(13) have led to a re-evaluation of the physics potential of the T2K long-baseline neutrino oscillation experiment. Sensitivities are explored for CP violation in neutrinos, non-maximal sin(2) 2 theta(23), the octant of theta(23), and the mass hierarchy, in addition to the measurements of delta CP, sin(2) theta(23), and Delta m(32)(2), for various combinations of nu-mode and (nu) over bar -mode data-taking. With an exposure of 7.8 x 10(21) protons-on-target, T2K can achieve 1 sigma resolution of 0.050 (0.054) on sin(2) theta(23) and 0.040 (0.045) x 10(-3) eV(2) on Delta m(32)(2) for 100% (50%) neutrino beam mode running assuming sin(2) theta(23) = 0.5 and Delta m(32)(2) = 2.4 x 10(-3) eV(2). T2K will have sensitivity to the CP-violating phase delta(CP) at 90% C.L. or better over a significant range. For example, if sin(2) 2 theta(23) is maximal (i.e.theta(23) = 45 degrees) the range is -115 degrees < delta(CP) < -60 degrees for normal hierarchy and +50 degrees < delta(CP) < + 130 degrees for inverted hierarchy. When T2K data is combined with data from the NO nu A experiment, the region of oscillation parameter space where there is sensitivity to observe a non-zero delta CP is substantially increased compared to if each experiment is analyzed alone.
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Aceti, F., Dias, J. M., & Oset, E. (2015). f(1)(1285) decays into a(0)(980) pi(0), f(0)(980) pi(0) and isospin breaking. Eur. Phys. J. A, 51(4), 48–8pp.
Abstract: We evaluate the decay width for the processes f1(1285). p 0 a0(980) and f1(1285). p 0 f0(980) taking into account that all three resonances are dynamically generated from the meson- meson interaction, the f1(1285) from K* K – c. c. and the a0(980), f0(980) from p., K K and pp, K _ K, respectively. We use a triangular mechanism similar to that of.(1405). pp., which provides a decay width for f1(1285). p 0 a0(980) with a branching fraction of the order of 30%, in agreement with experiment. At the same time we evaluate the decay width for the isospin- forbidden f1(1285). p 0 f0(980), which appears when we consider different masses for the charged and neutral kaons, and show that it is much more suppressed than in the.(1405). pp. case, but gives rise to a narrow shape of the p + p- distribution similar to the one found in the eta(1405) -> pi pi eta decay.
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Aceti, F., Xie, J. J., & Oset, E. (2015). The K(K)over-bar pi decay of the f(1) (1285) and its nature as a K*(K)over-bar – cc molecule. Phys. Lett. B, 750, 609–614.
Abstract: We investigate the decay of f(1) (1285) > pi K (K) over bar with the assumption that the f(1) (1285) is dynamically generated from the K*(K) over bar – cc interaction. In addition to the tree level diagrams that proceed via f(1)(1285) -> K*(K) over bar – cc -> pi K (K) over bar, we take into account also the final state interactions of K (K) over bar -> K (K) over bar and pi K -> pi K. The partial decay width and mass distributions of f(1) (1285) -> pi K (K) over bar are evaluated. We get a value for the partial decay width which, within errors, is in fair agreement with the experimental result. The contribution from the tree level diagrams is dominant, but the final state interactions have effects in the mass distributions. The predicted mass distributions are significantly different from phase space and tied to the K*(K) over bar – cc nature of the f(1) (1285) state.
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Achterberg, A., Amoroso, S., Caron, S., Hendriks, L., Ruiz de Austri, R., & Weniger, C. (2015). A description of the Galactic Center excess in the Minimal Supersymmetric Standard Model. J. Cosmol. Astropart. Phys., 08(8), 006–27pp.
Abstract: Observations with the Fermi Large Area Telescope (LAT) indicate an excess in gamma rays originating from the center of our Galaxy. A possible explanation for this excess is the annihilation of Dark Matter particles. We have investigated the annihilation of neutralinos as Dark Matter candidates within the phenomenological Minimal Supersymmetric Standard Model (pMSSM). An iterative particle filter approach was used to search for solutions within the pMSSM. We found solutions that are consistent with astroparticle physics and collider experiments, and provide a fit to the energy spectrum of the excess. The neutralino is a Bino/Higgsino or Bino/Wino/Higgsino mixture with a mass in the range 84-92 GeV or 87-97 GeV annihilating into W bosons. A third solutions is found for a neutralino of mass 174-187 GeV annihilating into top quarks. The best solutions yield a Dark Matter relic density 0.06 < Omega h(2) < 0.13. These pMSSM solutions make clear forecasts for LHC, direct and indirect DM detection experiments. If the pMSSM explanation of the excess seen by Fermi-LAT is correct, a DM signal might be discovered soon.
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