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Xie, J. J., Albaladejo, M., & Oset, E. (2014). Signature of an h(1) state in the J/psi -> eta h(1) -> eta K*(0)(K)over-bar*(0) decay. Phys. Lett. B, 728, 319–322.
Abstract: The BES data on the J/psi -> eta K*(0)(K) over bar*(0) reaction show a clear enhancement in the K*(0)(K) over bar*(0) mass distribution close to the threshold of this channel. Such an enhancement is usually a signature of an L = 0 resonance around threshold, which in this case would correspond to an h1 state with quantum numbers I-G(J(Pc))= 0(-)(1(+-)). A state around 1800 MeV results from the interaction of the K*TC* using the local hidden gauge approach. We show that the peak observed in J/psi -> eta K*(0)(K) over bar*(0) naturally comes from the creation of this h(1) state with mass and width around 1830 MeV and 110 MeV, respectively. A second analysis, model independent, corroborates the first result, confirming the relationship of the enhancement in the invariant mass spectrum with the h(1) resonance.
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Wimmer, K. et al, Algora, A., & Rubio, B. (2018). Shape coexistence and isospin symmetry in A=70 nuclei: Spectroscopy of the T-z =-1 nucleus Kr-70. Phys. Lett. B, 785, 441–446.
Abstract: Excited states in the T-z = -1 nucleus Kr-70 have been populated using inelastic scattering of a radioactive Kr-70 beam as well as one- and two-neutron removal reactions from Kr-71,Kr-72 at intermediate beam energies. The level scheme of Kr-70 was constructed from the observed gamma-ray transitions and coincidences. Tentative spin and parity assignments were made based on comparison with the mirror nucleus Se-70. Asecond 2(+) state and a candidate for the corresponding 4(2)(+) state suggest shape coexistence in Kr-70.
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Kosmas, T. S., Miranda, O. G., Papoulias, D. K., Tortola, M., & Valle, J. W. F. (2015). Sensitivities to neutrino electromagnetic properties at the TEXONO experiment. Phys. Lett. B, 750, 459–465.
Abstract: The possibility of measuring neutral-current coherent elastic neutrino nucleus scattering (CENNS) at the TEXONO experiment has opened high expectations towards probing exotic neutrino properties. Focusing on low threshold Germanium-based targets with kg-scale mass, we find a remarkable efficiency not only for detecting CENNS events due to the weak interaction, but also for probing novel electromagnetic neutrino interactions. Specifically, we demonstrate that such experiments are complementary in performing precision Standard Model tests as well as in shedding light on sub-leading effects due to neutrino magnetic moment and neutrino charge radius. This work employs realistic nuclear structure calculations based on the quasi-particle random phase approximation (QRPA) and takes into consideration the crucial quenching effect corrections. Such a treatment, in conjunction with a simple statistical analysis, shows that the attainable sensitivities are improved by one order of magnitude as compared to previous studies.
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Centelles Chulia, S., Srivastava, R., & Valle, J. W. F. (2018). Seesaw roadmap to neutrino mass and dark matter. Phys. Lett. B, 781, 122–128.
Abstract: We describe the many pathways to generate Majorana and Dirac neutrino mass through generalized dimension-5 operators a la Weinberg. The presence of new scalars beyond the Standard Model Higgs doublet implies new possible field contractions, which are required in the case of Dirac neutrinos. We also notice that, in the Dirac neutrino case, the extra symmetries needed to ensure the Dirac nature of neutrinos can also be made responsible for stability of dark matter.
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NEXT Collaboration(Henriques, C. A. O. et al), Gomez-Cadenas, J. J., Alvarez, V., Benlloch-Rodriguez, J., Botas, A., Carcel, S., et al. (2017). Secondary scintillation yield of xenon with sub-percent levels of CO2 additive for rare-event detection. Phys. Lett. B, 773, 663–671.
Abstract: Xe-CO2 mixtures are important alternatives to pure xenon in Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification with applications in the important field of rare event detection such as directional dark matter, double electron capture and double beta decay detection. The addition of CO2 to pure xenon at the level of 0.05-0.1% can reduce significantly the scale of electron diffusion from 10 mm/root m to 2.5 mm/root m, with high impact on the discrimination of the events through pattern recognition of the topology of primary ionization trails. We have measured the electroluminescence (EL) yield of Xe-CO2 mixtures, with sub-percent CO2 concentrations. We demonstrate that the EL production is still high in these mixtures, 70% and 35% relative to that produced in pure xenon, for CO2 concentrations around 0.05% and 0.1%, respectively. The contribution of the statistical fluctuations in EL production to the energy resolution increases with increasing CO2 concentration, being smaller than the contribution of the Fano factor for concentrations below 0.1% CO2.
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Freitas, E. D. C., Monteiro, C. M. B., Ball, M., Gomez-Cadenas, J. J., Lopes, J. A. M., Lux, T., et al. (2010). Secondary scintillation yield in high-pressure xenon gas for neutrinoless double beta decay (0 nu beta beta) search. Phys. Lett. B, 684(4-5), 205–210.
Abstract: The search for neutrinoless double beta decay (0 nu beta beta) is an important topic in contemporary physics with many active experiments. New projects are planning to use high-pressure xenon gas as both source and detection medium. The secondary scintillation processes available in noble gases permit large amplification with negligible statistical fluctuations, offering the prospect of energy resolution approaching the Fano factor limit. This Letter reports results for xenon secondary scintillation yield, at room temperature, as a function of electric field in the gas scintillation gap for pressures ranging from 2 to 10 bar. A Large Area Avalanche Photodiode (LAAPD) collected the VUV secondary scintillation produced in the gas. X-rays directly absorbed in the LAAPD are used as a reference for determining the number of charge carriers produced by the scintillation pulse and, hence, the number of photons impinging the LAAPD. The number of photons produced per drifting electron and per kilovolt, the so-called scintillation amplification parameter, displays a small increase with pressure, ranging from 141 +/- 6 at 2 bar to 170 +/- 10 at 8 bar. In our setup, this Parameter does not increase above 8 bar due to nonnegligible electron attachment. The results are in good agreement with those presented in the literature in the 1 to 3 bar range. The increase of the scintillation amplification parameter with pressure for high gas densities has been also observed in former work at cryogenic temperatures.
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Sanchis-Lozano, M. A., & Sarkisyan-Grinbaum, E. K. (2018). Searching for new physics with three-particle correlations in pp collisions at the LHC. Phys. Lett. B, 781, 505–509.
Abstract: New phenomena involving pseudorapidity and azimuthal correlations among final-state particles in pp collisions at the LHC can hint at the existence of hidden sectors beyond the Standard Model. In this paper we rely on a correlated-cluster picture of multiparticle production, which was shown to account for the ridge effect, to assess the effect of a hidden sector on three-particle correlations concluding that there is a potential signature of new physics that can be directly tested by experiments using well-known techniques.
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Sanchis-Lozano, M. A., Sarkisyan-Grinbaum, E. K., & Moreno-Picot, S. (2016). Searching for hidden sector in multiparticle production at LHC. Phys. Lett. B, 754, 353–359.
Abstract: We study the impact of a hidden sector beyond the Standard Model, e.g. a Hidden Valley model, on factorial moments and cumulants of multiplicity distributions in multiparticle production with a special emphasis on the prospects for LHC results.
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LHCb Collaboration(Aaij, R. et al), Oyanguren, A., & Ruiz Valls, P. (2013). Searches for violation of lepton flavour and baryon number in tau lepton decays at LHCb. Phys. Lett. B, 724(1-3), 36–45.
Abstract: Searches for the lepton flavour violating decay tau(-) -> mu(-)mu(+)mu(-) and the lepton flavour and baryon number violating decays tau(-) -> (p) over bar mu(+)mu(-) and tau(-) -> p mu(-)mu(-) have been carried out using proton-proton collision data, corresponding to an integrated luminosity of 1.0 fb(-1), taken by the LHCb experiment at root s = 7 TeV. No evidence has been found for any signal, and limits have been set at 90% confidence level on the branching fractions: B(tau(-) -> mu(-)mu(+)mu(-) < 8.0 x 10(-8), B(tau(-) -> <(p)over bar>mu(+)mu(-)) < 3.3 x 10(-7) and B(tau(-) -> p mu(-)mu(-)) < 4.4 x 10(-7). The results for the tau(-) -> (p) over bar mu(+)mu(-) and tau(-) -> p mu(-)mu(-) decay modes represent the first direct experimental limits on these channels.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., et al. (2012). Searches for supersymmetry with the ATLAS detector using final states with two leptons and missing transverse momentum in root s=7 TeV proton-proton collisions. Phys. Lett. B, 709(3), 137–157.
Abstract: Results of three searches are presented for the production of supersymmetric particles decaying into final states with missing transverse momentum and exactly two isolated leptons, e or mu. The analysis uses a data sample collected during the first half of 2011 that corresponds to a total integrated luminosity of 1 fb(-1) of root s = 7 TeV proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider. Opposite-sign and same-sign dilepton events are separately studied, with no deviations from the Standard Model expectation observed. Additionally, in opposite-sign events, a search is made for an excess of same-flavour over different-flavour lepton pairs. Effective production cross sections in excess of 9.9 fb for opposite-sign events containing supersymmetric particles with missing transverse momentum greater than 250 GeV are excluded at 95% CL For same-sign events containing supersymmetric particles with missing transverse momentum greater than 100 GeV, effective production cross sections in excess of 14.8 fb are excluded at 95% CL The latter limit is interpreted in a simplified electroweak gaugino production model excluding chargino masses up to 200 GeV, under the assumption that slepton decay is dominant.
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