Chala, M., Delgado, A., Nardini, G., & Quiros, M. (2017). A light sneutrino rescues the light stop. J. High Energy Phys., 04(4), 097–22pp.
Abstract: Stop searches in supersymmetric frameworks with R-parity conservation usually assume the lightest neutralino to be the lightest supersymmetric particle. In this paper we consider an alternative scenario in which the left-handed tau sneutrino is lighter than neutralinos and stable at collider scales, but possibly unstable at cosmological scales. Moreover the (mostly right-handed) stop (t) over tilde is lighter than all electroweakinos, and heavier than the scalars of the third generation lepton doublet, whose charged component, (T) over tilde, is heavier than the neutral one, (v) over tilde. The remaining supersymmetric particles are decoupled from the stop phenomenology. In most of the parameter space, the relevant stop decays are only into t (T) over tildeT, t (v) over tildev and b (v) over tildeT via off-shell electroweakinos. We constrain the branching ratios of these decays by recasting the most sensitive stop searches. Due to the “double invisible” kinematics of the (t) over tilde -> t (v) over tildev process, and the low efficiency in tagging the t (T) over tildeT decay products, light stops are generically allowed. In the minimal supersymmetric standard model with similar to 100 GeV sneutrinos, stops with masses as small as similar to 350 GeV turn out to be allowed at 95% CL.
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Escudero, M., Witte, S. J., & Hooper, D. (2017). Hidden sector dark matter and the Galactic Center gamma-ray excess: a closer look. J. Cosmol. Astropart. Phys., 11(11), 042–29pp.
Abstract: Stringent constraints from direct detection experiments and the Large Hadron Collider motivate us to consider models in which the dark matter does not directly couple to the Standard Model, but that instead annihilates into hidden sector particles which ultimately decay through small couplings to the Standard Model. We calculate the gamma-ray emission generated within the context of several such hidden sector models, including those in which the hidden sector couples to the Standard Model through the vector portal (kinetic mixing with Standard Model hypercharge), through the Higgs portal (mixing with the Standard Model Higgs boson), or both. In each case, we identify broad regions of parameter space in which the observed spectrum and intensity of the Galactic Center gamma-ray excess can easily be accommodated, while providing an acceptable thermal relic abundance and remaining consistent with all current constraints. We also point out that cosmic-ray antiproton measurements could potentially discriminate some hidden sector models from more conventional dark matter scenarios.
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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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KM3NeT Collaboration(Adrian-Martinez, S. et al), Barrios-Marti, J., Calvo, D., Hernandez-Rey, J. J., Illuminati, G., Lotze, M., et al. (2017). Intrinsic limits on resolutions in muon- and electron-neutrino charged-current events in the KM3NeT/ORCA detector. J. High Energy Phys., 05(5), 008–39pp.
Abstract: Studying atmospheric neutrino oscillations in the few-GeV range with a multimegaton detector promises to determine the neutrino mass hierarchy. This is the main science goal pursued by the future KM3NeT/ORCA water Cherenkov detector in the Mediterranean Sea. In this paper, the processes that limit the obtainable resolution in both energy and direction in charged-current neutrino events in the ORCA detector are investigated. These processes include the composition of the hadronic fragmentation products, the subsequent particle propagation and the photon-sampling fraction of the detector. GEANT simulations of neutrino interactions in seawater produced by GENIE are used to study the effects in the 1-20 GeV range. It is found that fluctuations in the hadronic cascade in conjunction with the variation of the inelasticity y are most detrimental to the resolutions. The effect of limited photon sampling in the detector is of significantly less importance. These results will therefore also be applicable to similar detectors/media, such as those in ice.
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Lopez-Ibañez, M. L., Melis, A., Jay Perez, M., & Vives, O. (2017). Slepton non-universality in the flavor-effective MSSM. J. High Energy Phys., 11(11), 162–27pp.
Abstract: Supersymmetric theories supplemented by an underlying flavor-symmetry G(f) provide a rich playground for model building aimed at explaining the flavor structure of the Standard Model. In the case where supersymmetry breaking is mediated by gravity, the soft-breaking Lagrangian typically exhibits large tree-level flavor violating e ff ects, even if it stems from an ultraviolet flavor-conserving origin. Building on previous work, we continue our phenomenological analysis of these models with a particular emphasis on leptonicflavor observables. We consider three representative models which aim to explain the flavor structure of the lepton sector, with symmetry groups G(f) = Delta (27), A(4); and S-3.
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