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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ANTARES Collaboration(Albert, A. et al), Barrios-Marti, J., Coleiro, A., Hernandez-Rey, J. J., Illuminati, G., Lotze, M., et al. (2017). First all-flavor neutrino pointlike source search with the ANTARES neutrino telescope. Phys. Rev. D, 96(8), 082001–15pp.
Abstract: A search for cosmic neutrino sources using the data collected with the ANTARES neutrino telescope between early 2007 and the end of 2015 is performed. For the first time, all neutrino interactions-charged and neutral-current interactions of all flavors-are considered in a search for point-like sources with the ANTARES detector. In previous analyses, only muon neutrino charged-current interactions were used. This is achieved by using a novel reconstruction algorithm for shower-like events in addition to the standard muon track reconstruction. The shower channel contributes about 23% of all signal events for an E-2 energy spectrum. No significant excess over background is found. The most signal-like cluster of events is located at (alpha, delta) = (343.8 degrees, 23.5 degrees) with a significance of 1.9 sigma. The neutrino flux sensitivity of the search is about E(2)d Phi/dE = 6 x 10(-9) GeV cm(-2) s(-1) for declinations from -90 degrees up to -42 degrees, and below 10(-8) GeV cm(-2) s(-1) for declinations up to 5 degrees. The directions of 106 source candidates and 13 muon track events from the IceCube high-energy sample events are investigated for a possible neutrino signal and upper limits on the signal flux are determined.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Observation of the Annihilation Decay Mode B-0 -> K+K-. Phys. Rev. Lett., 118(8), 081801–9pp.
Abstract: A search for the B-0 -> K+K- decay is performed using pp-collision data collected by LHCb. The data set corresponds to integrated luminosities of 1.0 and 2.0 fb(-1) at center-of-mass energies of 7 and 8 TeV, respectively. This decay is observed for the first time, with a significance of more than 5 standard deviations. The analysis also results in an improved measurement of the branching fraction for the B-s(0) -> pi(+)pi(-) decay. The measured branching fractions are B(B-0 -> K+K-) = (7.80 +/- 1.27 +/- 0.81 +/- 0.21) x 10(-8) and B(B-s(0) -> pi(+)p(-)) = (6.91 +/- 0.54 +/- 0.63 +/- 0.19 +/- 0.40) x 10(-7). The first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the B-0 -> K+pi(-) branching fraction used as a normalization. For the B-s(0) mode, the fourth accounts for the uncertainty on the ratio of the probabilities for b quarks to hadronize into B-s(0) and B-0 mesons.
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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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Fileviez Perez, P., & Murgui, C. (2017). Lepton flavor violation in left-right theory. Phys. Rev. D, 95(7), 075010–12pp.
Abstract: We investigate the predictions for lepton flavor number violating processes in the context of a simple left-right symmetric theory. In this context neutrinos are Majorana fermions and their masses are generated at the quantum level through the Zee mechanism using the simplest Higgs sector. We show that the right-handed neutrinos are generically light and can give rise to large lepton flavor violating contributions to rare processes. We discuss the correlation between the collider constraints and the predictions for lepton flavor violating processes. We find that using the predictions for μ-> e gamma and μ-> e conversion together with the collider signatures one could test this theory in the near future.
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Aitken, K., McKeen, D., Neder, T., & Nelson, A. E. (2017). Baryogenesis from oscillations of charmed or beautiful baryons. Phys. Rev. D, 96(7), 075009–15pp.
Abstract: We propose a model for CP-violating oscillations of neutral, heavy-flavor baryons into antibaryons at rates which are within a few orders of magnitude of their lifetimes. The flavor structure of the baryon violation suppresses neutron oscillations and baryon-number-violating nuclear decays to experimentally allowed rates. We also propose a scenario for producing such baryons in the early Universe via the out-of-equilibrium decays of a neutral particle, after hadronization but before nucleosynthesis. We find parameters where CP-violating baryon oscillations at a temperature of a few MeV could result in the observed asymmetry between baryons and antibaryons. Furthermore, part of the relevant parameter space for baryogenesis is potentially testable at Belle II via decays of heavy-flavor baryons into an exotic neutral fermion. The model introduces four new particles: three light Majorana fermions and a colored scalar. The lightest of these fermions is typically long lived on collider time scales and may be produced in decays of bottom and possibly charmed hadrons.
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Abbas, G., Zahiri-Abyaneh, M., & Srivastava, R. (2017). Precise predictions for Dirac neutrino mixing. Phys. Rev. D, 95(7), 075005–7pp.
Abstract: The neutrino mixing parameters are thoroughly studied using renormalization- group evolution of Dirac neutrinos with recently proposed parametrization of the neutrino mixing angles referred to as “high-scale mixing relations.” The correlations among all neutrino mixing and CP violating observables are investigated. The predictions for the neutrino mixing angle. 23 are precise, and could be easily tested by ongoing and future experiments. We observe that the high-scale mixing unification hypothesis is incompatible with Dirac neutrinos due to updated experimental data.
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Gonzalez, P. (2017). A quark model study of strong decays of X(3915). J. Phys. G, 44(7), 075004–13pp.
Abstract: Strong decays of X(3915) are analyzed from two quark model descriptions of X(3915), a conventional one in terms of the Cornell potential and an unconventional one from a generalized screened potential. We conclude that the experimental suppression of the OZI allowed decay X(3915) -> D (D) over bar might be explained in both cases due to the momentum dependence of the decay amplitude. However, the experimental significance of the OZI forbidden decay X(3915) -> omega J/psi could favor an unconventional description.
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Ayala, C., Cvetic, G., & Kogerler, R. (2017). Lattice-motivated holomorphic nearly perturbative QCD. J. Phys. G, 44(7), 075001–30pp.
Abstract: Newer lattice results indicate that, in the Landau gauge at low spacelike momenta, the gluon propagator and the ghost dressing function are finite non-zero. This leads to a definition of the QCD running coupling, in a specific scheme, that goes to zero at low spacelike momenta. We construct a running coupling which fulfills these conditions, and at the same time reproduces to a high precision the perturbative behavior at high momenta. The coupling is constructed in such a way that it reflects qualitatively correctly the holomorphic (analytic) behavior of spacelike observables in the complex plane of the squared momenta, as dictated by the general principles of quantum field theories. Further, we require the coupling to reproduce correctly the nonstrange semihadronic decay rate of tau lepton which is the best measured low-momentum QCD observable with small higher-twist effects. Subsequent application of the Borel sum rules to the V + A spectral functions of tau lepton decays, as measured by OPAL Collaboration, determines the values of the gluon condensate and of the V + A six-dimensional condensate, and reproduces the data to a significantly higher precision than the usual (MS) over bar running coupling.
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Garcilazo, H., Valcarce, A., & Vijande, J. (2017). (4)(Lambda Lambda) n system. Chin. Phys. C, 41(7), 074102–6pp.
Abstract: Using local central Yukawa-type Malfliet-Tjon interactions reproducing the low-energy parameters and phase shifts of the nn system, and the latest updates of the n Lambda and Lambda Lambda Nijmegen ESCO8c potentials, we study the possible existence of a (4)(Lambda Lambda)n bound state. Our results indicate that the (4)(Lambda Lambda)n is unbound, being just above threshold. We discuss the role played by the S-1(0) nn repulsive term of the Yukawa-type Malfliet-Tjon interaction.
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