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Altheimer, A. et al, Fassi, F., Gonzalez de la Hoz, S., Kaci, M., Oliver Garcia, E., Rodrigo, G., et al. (2014). Boosted objects and jet substructure at the LHC. Eur. Phys. J. C, 74(3), 2792–24pp.
Abstract: This report of the BOOST2012 workshop presents the results of four working groups that studied key aspects of jet substructure. We discuss the potential of first-principle QCD calculations to yield a precise description of the substructure of jets and study the accuracy of state-of-the-art Monte Carlo tools. Limitations of the experiments' ability to resolve substructure are evaluated, with a focus on the impact of additional (pile-up) proton proton collisions on jet substructure performance in future LHC operating scenarios. A final section summarizes the lessons learnt from jet substructure analyses in searches for new physics in the production of boosted top quarks.
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Jones Perez, J. (2014). Split-family SUSY, U(2)(5) flavour symmetry and neutrino physics. Eur. Phys. J. C, 74(2), 2772–9pp.
Abstract: In split-family SUSY, one can use a U(2)(3) symmetry to protect flavour observables in the quark sector from SUSY contributions. However, attempts to extend this procedure to the lepton sector by using an analogous U(2)(5) symmetry fail to reproduce the neutrino data without introducing some form of fine-tuning. In this work, we solve this problem by shifting the U(2)(2) symmetry acting on leptons towards the second and third generations. This allows neutrino data to be reproduced without much difficulties, as well as protecting the leptonic flavour observables from SUSY. Key signatures are a μ-> e gamma branching ratio possibly observable in the near future, as well as having selectrons as the lightest sleptons.
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Herrera-Aguilar, A., Rojas, A. D., & Santos, E. (2014). Localization of gauge fields in a tachyonic de Sitter thick braneworld. Eur. Phys. J. C, 74(4), 2770–6pp.
Abstract: In this work we show that universal gauge vector fields can be localized on the recently proposed 5D thick tachyonic braneworld which involves a de Sitter cosmological background induced on the 3-brane. Namely, by performing a suitable decomposition of the vector field, the resulting 4D effective action corresponds to a massive gauge field, while the profile along the extra dimension obeys a Schrodinger-like equation with a Poschl-Teller potential. It turns out that the massless zero mode of the gauge field is bound to the expanding 3-brane and allows us to recover the standard 4D electromagnetic phenomena of our world. Moreover, this zero mode is separated from the continuum of Kaluza-Klein (KK) modes by a mass gap determined by the scale of the expansion parameter. We also were able to analytically solve the corresponding Schrodinger-like equation for arbitrary mass, showing that KK massive modes asymptotically behave like plane waves, as expected.
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ANTARES Collaboration(Adrian-Martinez, S. et al), Barrios-Marti, J., Bigongiari, C., Emanuele, U., Gomez-Gonzalez, J. P., Hernandez-Rey, J. J., et al. (2014). A search for neutrino emission from the Fermi bubbles with the ANTARES telescope. Eur. Phys. J. C, 74(2), 2701–7pp.
Abstract: Analysis of the Fermi-LAT data has revealed two extended structures above and below the Galactic Centre emitting gamma rays with a hard spectrum, the so-called Fermi bubbles. Hadronic models attempting to explain the origin of the Fermi bubbles predict the emission of high-energy neutrinos and gamma rays with similar fluxes. The ANTARES detector, a neutrino telescope located in the Mediterranean Sea, has a good visibility to the Fermi bubble regions. Using data collected from 2008 to 2011 no statistically significant excess of events is observed and therefore upper limits on the neutrino flux in TeV range from the Fermi bubbles are derived for various assumed energy cutoffs of the source.
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D'Ambrosio, G., Greynat, D., & Vulvert, G. (2013). Standard model and new physics contributions to K (L) and K (S) into four leptons. Eur. Phys. J. C, 73(12), 2678–10pp.
Abstract: We study the K (L) and K (S) decays into four leptons (, , ) where we use a form factor motivated by vector meson dominance, and show the dependence of the branching ratios and spectra from the slopes. A precise determination of short-distance contribution to K (L) ->mu μis affected by our ignorance on the sign of the amplitude but we show a possibility to measure the sign of this amplitude by studying K (L) and K (S) decays in four leptons. We also investigate the effect of New Physics contributions for these decays.
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