Chakraborty, K., Goswami, S., Gupta, C., & Thakore, T. (2019). Enhancing the hierarchy and octant sensitivity of ESS nu SB in conjunction with T2K, NO nu A and ICAL@INO. J. High Energy Phys., 05(5), 137–26pp.
Abstract: The main aim of the ESSSB proposal is the discovery of the leptonic CP phase (CP) with a high significance (5 sigma for 50% values of (CP)) by utilizing the physics at the second oscillation maxima of the P-e channel. It can achieve 3 sigma sensitivity to hierarchy for all values of (CP). In this work, we concentrate on the hierarchy and octant sensitivity of the ESSSB experiment. We show that combining the ESSSB experiment with the atmospheric neutrino data from the proposed India-based Neutrino Observatory (INO) experiment can result in an increased sensitivity to mass hierarchy. In addition, we also combine the results from the ongoing experiments T2K and NOa assuming their full run-time and present the combined sensitivity of ESSSB + ICAL@INO + T2K + NOA. We show that while by itself ESSSB can have up to 3 sigma hierarchy sensitivity, the combination of all the experiments can give up to 5 sigma sensitivity depending on the true hierarchy-octant combination. The octant sensitivity of ESSSB is low by itself. However the combined sensitivity of all the above experiments can give up to 3 sigma sensitivity depending on the choice of true hierarchy and octant. We discuss the various degeneracies and the synergies that lead to the enhanced sensitivity when combining different experimental data.
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Centelles Chulia, S., Doring, C., Rodejohann, W., & Saldana-Salazar, U. J. (2020). Natural axion model from flavour. J. High Energy Phys., 09(9), 137–29pp.
Abstract: We explore a common symmetrical origin for two long standing problems in particle physics: the strong CP and the fermion mass hierarchy problems. The Peccei-Quinn mechanism solves the former one with an anomalous global U(1)(PQ) symmetry. Here we investigate how this U(1)(PQ) could at the same time explain the fermion mass hierarchy. We work in the context of a four-Higgs-doublet model which explains all quark and charged fermion masses with natural, i.e. order 1, Yukawa couplings. Moreover, the axion of the model constitutes a viable dark matter candidate and neutrino masses are incorporated via the standard type-I seesaw mechanism. A simple extension of the model allows for Dirac neutrinos.
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De Romeri, V., Karamitros, D., Lebedev, O., & Toma, T. (2020). Neutrino dark matter and the Higgs portal: improved freeze-in analysis. J. High Energy Phys., 10(10), 137–41pp.
Abstract: Sterile neutrinos are one of the leading dark matter candidates. Their masses may originate from a vacuum expectation value of a scalar field. If the sterile neutrino couplings are very small and their direct coupling to the inflaton is forbidden by the lepton number symmetry, the leading dark matter production mechanism is the freeze-in scenario. We study this possibility in the neutrino mass range up to 1 GeV, taking into account relativistic production rates based on the Bose-Einstein statistics, thermal masses and phase transition effects. The specifics of the production mechanism and the dominant mode depend on the relation between the scalar and sterile neutrino masses as well as on whether or not the scalar is thermalized. We find that the observed dark matter abundance can be produced in all of the cases considered. We also revisit the freeze-in production of a Higgs portal scalar, pointing out the importance of a fusion mode, as well as the thermalization constraints.
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Barenboim, G., & Rasero, J. (2014). Structure formation during an early period of matter domination. J. High Energy Phys., 04(4), 138–17pp.
Abstract: In this work we show that modifying the thermal history of the Universe by including an early period of matter domination can lead to the formation of astronomical objects. However, the survival of these objects can only be possible if the dominating matter decays to a daughter particle which is not only almost degenerate with the parent particle but also has an open annihilation channel. This requirement translates in an upper bound for the coupling of such a channel and makes the early structure formation viable.
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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. (2018). Search for charged Higgs bosons decaying via H-+/- -> tau(+/-)nu(tau) in the tau plus jets and tau plus lepton final states with 36 fb(-1) of pp collision data recorded at root s=13 TeV with the ATLAS experiment. J. High Energy Phys., 09(9), 139–48pp.
Abstract: Charged Higgs bosons produced either in top-quark decays or in association with a top-quark, subsequently decaying via H-+/-! -> tau(+/-)nu(tau), are searched for in 36.1 fb(-1) of proton-proton collision data at root s = 13TeV recorded with the ATLAS detector. Depending on whether the top-quark produced together with H-+/- decays hadronically or leptonically, the search targets tau+jets and tau+lepton fi nal states, in both cases with a hadronically decaying tau-lepton. No evidence of a charged Higgs boson is found. For the mass range of m(H)+/- = 90-2000 GeV, upper limits at the 95% con fi dence level are set on the production cross-section of the charged Higgs boson times the branching fraction B (H-+/-->tau(+/-)nu(tau)) in the range 4.2-0.0025 pb. In the mass range 90{160 GeV, assuming the Standard Model cross-section for tit production, this corresponds to upper limits between 0.25% and 0.031% for the branching fraction B (t -> bH(+/-)) x B (H-+/- -> tau(+/-)nu(tau)).
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