Binosi, D., Chang, L., Ding, M. H., Gao, F., Papavassiliou, J., & Roberts, C. D. (2019). Distribution amplitudes of heavy-light mesons. Phys. Lett. B, 790, 257–262.
Abstract: A symmetry-preserving approach to the continuum bound-state problem in quantum field theory is used to calculate the masses, leptonic decay constants and light-front distribution amplitudes of empirically accessible heavy-light mesons. The inverse moment of the B-meson distribution is particularly important in treatments of exclusive B-decays using effective field theory and the factorisation formalism; and its value is therefore computed: lambda(B) = (zeta = 2GeV) = 0.54(3) GeV. As an example and in anticipation of precision measurements at new-generation B-factories, the branching fraction for the rare B -> gamma (E-gamma)l nu(l) radiative decay is also calculated, retaining 1/m(B)(2), and 1/E-gamma(2) corrections to the differential decay width, with the result Gamma(B -> gamma l nu l) /Gamma(B) = 0.47 (15) on E-gamma > 1.5 GeV.
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Reig, M., Restrepo, D., Valle, J. W. F., & Zapata, O. (2019). Bound-state dark matter with Majorana neutrinos. Phys. Lett. B, 790, 303–307.
Abstract: We propose a simple scenario in which dark matter (DM) emerges as a stable neutral hadronic thermal relic, its stability following from an exact U(1)(D) symmetry. Neutrinos pick up radiatively induced Majorana masses from the exchange of colored DM constituents. There is a common origin for both dark matter and neutrino mass, with a lower bound for neutrinoless double beta decay. Direct DM searches at nuclear recoil experiments will test the proposal, which may also lead to other phenomenological signals at future hadron collider and lepton flavor violation experiments.
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n_TOF Collaboration(Lederer-Woods, C. et al), Domingo-Pardo, C., Tain, J. L., & Tarifeño-Saldivia, A. (2019). Measurement of Ge-73(n, gamma) cross sections and implications for stellar nucleosynthesis. Phys. Lett. B, 790, 458–465.
Abstract: Ge-73(n, gamma) cross sections were measured at the neutron time-of-flight facility n_TOF at CERN up to neutron energies of 300 keV, providing for the first time experimental data above 8 keV. Results indicate that the stellar cross section at kT = 30 keV is 1.5 to 1.7 times higher than most theoretical predictions. The new cross sections result in a substantial decrease of Ge-73 produced in stars, which would explain the low isotopic abundance of Ge-73 in the solar system.
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BRIKEN Collaboration(Tolosa-Delgado, A. et al), Agramunt, J., Tain, J. L., Algora, A., Domingo-Pardo, C., Morales, A. I., et al. (2019). Commissioning of the BRIKEN detector for the measurement of very exotic beta-delayed neutron emitters. Nucl. Instrum. Methods Phys. Res. A, 925, 133–147.
Abstract: A new detection system has been installed at the RIKEN Nishina Center (Japan) to investigate decay properties of very neutron-rich nuclei. The setup consists of three main parts: a moderated neutron counter, a detection system sensitive to the implantation and decay of radioactive ions, and gamma-ray detectors. We describe here the setup, the commissioning experiment and some selected results demonstrating its performance for the measurement of half-lives and beta-delayed neutron emission probabilities. The methodology followed in the analysis of the data is described in detail. Particular emphasis is placed on the correction of the accidental neutron background.
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ATLAS Collaboration(Aaboud, M. et al), Alvarez Piqueras, D., Aparisi Pozo, J. A., Bailey, A. J., Barranco Navarro, L., Cabrera Urban, S., et al. (2019). Study of the hard double-parton scattering contribution to inclusive four-lepton production in pp collisions at root s=8 TeV with the ATLAS detector. Phys. Lett. B, 790, 595–614.
Abstract: The inclusive production of four isolated charged leptons in pp collisions is analysed for the presence of hard double-parton scattering, using 20.2 fb(-1) of data recorded in the ATLAS detector at the LHC at centre-of-mass energy root s = 8 TeV. In the four-lepton invariant-mass range of 80 < m(4l) < 1000 GeV, an artificial neural network is used to enhance the separation between single- and double-parton scattering based on the kinematics of the four leptons in the final state. An upper limit on the fraction of events originating from double-parton scattering is determined at 95% confidence level to be f(DPS) = 0.042, which results in an estimated lower limit on the effective cross section at 95% confidence level of 1.0 mb.
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Richard, J. M., Valcarce, A., & Vijande, J. (2019). Pentaquarks with anticharm or beauty revisited. Phys. Lett. B, 790, 248–250.
Abstract: We use a constituent model to analyze the stability of pentaquark (Q) over bar qqqq configurations with a heavy antiquark (c) over bar or (b) over bar, and four light quarks uuds, ddsu or ssud. The interplay between chromoelectric and chromomagnetic effects is not favorable, and, as a consequence, no bound state is found below the lowest dissociation threshold.
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Llosa, G. (2019). SiPM-based Compton cameras. Nucl. Instrum. Methods Phys. Res. A, 926, 148–152.
Abstract: Compton cameras have been developed for almost fifty years in various fields (astronomy, medical imaging, safety and industrial inspections, etc.), employing different types of detectors. Their potential use has gained renewed interest with the emergence of high light yield scintillator crystals and silicon photomultipliers (SiPMs). This combination provides good performance and operation simplicity at an affordable cost, raising again the interest in this type of systems. SiPM-based Compton cameras are being assessed for diverse applications with promising results.
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Valiente-Dobon, J. J. et al, Egea, J., Huyuk, T., Gadea, A., Aliaga, R., Jurado-Gomez, M. L., et al. (2019). NEDA-NEutron Detector Array. Nucl. Instrum. Methods Phys. Res. A, 927, 81–86.
Abstract: The NEutron Detector Array, NEDA, will form the next generation neutron detection system that has been designed to be operated in conjunction with gamma-ray arrays, such as the tracking-array AGATA, to aid nuclear spectroscopy studies. NEDA has been designed to be a versatile device, with high-detection efficiency, excellent neutron-gamma discrimination, and high rate capabilities. It will be employed in physics campaigns in order to maximise the scientific output, making use of the different stable and radioactive ion beams available in Europe. The first implementation of the neutron detector array NEDA with AGATA 1 pi was realised at GANIL. This manuscript reviews the various aspects of NEDA.
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NA62 Collaboration(Cortina Gil, E. et al), & Husek, T. (2019). First search for K+ -> pi(+) nu(nu)over-bar using the decay-in-flight technique. Phys. Lett. B, 791, 156–166.
Abstract: The NA62 experiment at the CERN SPS reports the first search for K+ -> pi(+) nu(nu) over bar using the decay-in-flight technique, based on a sample of 1.21 x10(11) K+ decays collected in 2016. The single event sensitivity is 3.15 x10(-10), corresponding to 0.267 Standard Model events. One signal candidate is observed while the expected background is 0.152 events. This leads to an upper limit of 14 x10(-10) on the K+ -> pi(+) nu(nu) over bar branching ratio at 95% CL.
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Barenboim, G., Denton, P. B., Parke, S. J., & Ternes, C. A. (2019). Neutrino oscillation probabilities through the looking glass. Phys. Lett. B, 791, 351–360.
Abstract: In this paper we review different expansions for neutrino oscillation probabilities in matter in the context of long-baseline neutrino experiments. We examine the accuracy and computational efficiency of different exact and approximate expressions. We find that many of the expressions used in the literature are not precise enough for the next generation of long-baseline experiments, but several of them are while maintaining comparable simplicity. The results of this paper can be used as guidance to both phenomenologists and experimentalists when implementing the various oscillation expressions into their analysis tools.
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