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Olmo, G. J. (2011). Palatini approach to modified gravity: f(R) theories and beyond. Int. J. Mod. Phys. D, 20(4), 413–462.
Abstract: We review the recent literature on modified theories of gravity in the Palatini approach. After discussing the motivations that lead to consider alternatives to Einstein's theory and to treat the metric and the connection as independent objects, we review several topics that have been recently studied within this framework. In particular, we provide an in-depth analysis of the cosmic speed-up problem, laboratory and solar system tests, the structure of stellar objects, the Cauchy problem, and bouncing cosmologies. We also discuss the importance of going beyond the f(R) models to capture other phenomenological aspects related with dark matter/energy and quantum gravity.
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Alioli, S., Fuster, J., Garzelli, M. V., Gavardi, A., Irles, A., Melini, D., et al. (2022). Phenomenology of t(t)over-barj plus X production at the LHC. J. High Energy Phys., 05(5), 146–63pp.
Abstract: We present phenomenological results for t (t) over barj + X production at the Large Hadron Collider, of interest for designing forthcoming experimental analyses of this process. We focus on those cases where the t (t) over barj + X process is considered as a signal. We discuss present theoretical uncertainties and the dependence on relevant input parameters entering the computation. For the R. distribution, which depends on the invariant mass of the t (t) over barj-system, we present reference predictions in the on-shell, (MS) over bar and MSR top-quark mass renormalization schemes, applying the latter scheme to this process for the first time. Our conclusions are particularly interesting for those analyses aiming at extracting the topquark mass from cross-section measurements.
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Batra, A., Bharadwaj, P., Mandal, S., Srivastava, R., & Valle, J. W. F. (2023). Phenomenology of the simplest linear seesaw mechanism. J. High Energy Phys., 07(7), 221–48pp.
Abstract: The linear seesaw mechanism provides a simple way to generate neutrino masses. In addition to Standard Model particles, it includes quasi-Dirac leptons as neutrino mass mediators, and a leptophilic scalar doublet seeding small neutrino masses. Here we review its associated physics, including restrictions from theory and phenomenology. The model yields potentially detectable μ-> e gamma rates as well as distinctive signatures in the production and decay of heavy neutrinos ( N-i) and the charged Higgs boson (H-+/-) arising from the second scalar doublet. We have found that production processes such as e(+) e(-) -> NN, e- gamma -> NH- and e(+) e(-) -> H (+) H- followed by the decay chain H-+/--> l(+/-) (i) N, N -> l`(+/-) (j) W (-/+) leads to striking lepton number violation signatures at high energies which may probe the Majorana nature of neutrinos.
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Ghoshal, A., Gouttenoire, Y., Heurtier, L., & Simakachorn, P. (2023). Primordial black hole archaeology with gravitational waves from cosmic strings. J. High Energy Phys., 08(8), 196–43pp.
Abstract: Light primordial black holes (PBHs) with masses smaller than 10(9) g (10(-24) M-circle dot) evaporate before the onset of Big-Bang nucleosynthesis, rendering their detection rather challenging. If efficiently produced, they may have dominated the universe energy density. We study how such an early matter-dominated era can be probed successfully using gravitational waves (GW) emitted by local and global cosmic strings. While previous studies showed that a matter era generates a single-step suppression of the GW spectrum, we instead find a double-step suppression for local-string GW whose spectral shape provides information on the duration of the matter era. The presence of the two steps in the GW spectrum originates from GW being produced through two events separated in time: loop formation and loop decay, taking place either before or after the matter era. The second step – called the knee – is a novel feature which is universal to any early matter-dominated era and is not only specific to PBHs. Detecting GWs from cosmic strings with LISA, ET, or BBO would set constraints on PBHs with masses between 10(6) and 10(9) g for local strings with tension G μ= 10(-11), and PBHs masses between 10(4) and 10(9) g for global strings with symmetry-breaking scale eta = 10(15) GeV. Effects from the spin of PBHs are discussed.
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Ghosh, P., Lopez-Fogliani, D. E., Mitsou, V. A., Muñoz, C., & Ruiz de Austri, R. (2014). Probing the μnu SSM with light scalars, pseudoscalars and neutralinos from the decay of a SM-like Higgs boson at the LHC. J. High Energy Phys., 11(11), 102–57pp.
Abstract: The “mu from nu” supersymmetric standard model (mu nu SSM) can accommodate the newly discovered Higgs-like scalar boson with a mass around 125GeV. This model provides a solution to the mu-problem and simultaneously reproduces correct neutrino physics by the simple use of right-handed neutrino superfields. These new superfields together with the introduced R-parity violation can produce novel and characteristic signatures of the μnu SSM at the LHC. We explore the signatures produced through two-body Higgs decays into the new states, provided that these states lie below in the mass spectrum. For example, a pair produced light neutralinos depending on the associated decay length can give rise to displaced multi-leptons/taus/jets/photons with small/moderate missing transverse energy. In the same spirit, a Higgs-like scalar decaying to a pair of scalars/pseudoscalars can produce final states with prompt multi-leptons/taus/jets/photons.
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