Global fits in the Georgi-Machacek model

Off the beaten track of scalar singlet and doublet extensions of the Standard Model, triplets combine an interesting LHC phenomenology with an explanation for neutrino masses. The Georgi-Machacek model falls into this category, but it has never been fully explored in a global fit. We use the {\texttt{HEPfit}} package to combine recent experimental Higgs data with theoretical constraints and obtain strong limits on the mixing angles and mass differences between the heavy new scalars as well as their decay widths. We also find that the current signal strength measurements allow for a Higgs to vector boson coupling with an opposite sign to the Standard Model, but this possibility can be ruled out by the lack of direct evidence for heavy Higgs states. For these hypothetical particles, we identify the dominant decay channels and extract bounds on their branching ratios from the global fit, which can be used to single out the decay patterns relevant for the experimental searches.Comment: 23 pages, 4 figures. In v2: 30 pages, 6 figures. Updated Higgs experimental data. Global fits updated. Major conclusions unchanged. In v3: 28 pages, 6 figures. Comments on other searches included in summary. Version accepted for publication in PR

Revisiting the LHC reach in the displaced region of the minimal left-right symmetric model

We revisit discovery prospects for a long-lived sterile neutrino $N$ at the Large Hadron Collider (LHC) in the context of left-right symmetric theories. We focus on a displaced vertex search strategy sensitive to $\mathcal{O}$(GeV) neutrino masses produced via a right-handed $W_{R}$ boson. Both on-shell and off-shell Drell-Yan production of $W_{R}$ are considered. We estimate the reach as a function of $m_{N}$ and $m_{W_{R}}$. With $\sqrt{s}=13$ TeV and 300/fb of integrated luminosity, the LHC can probe neutrino masses as high as $\sim 30$ GeV and $m_{W_{R}}$ around 6 TeV. The reach goes up to 11.5 TeV with 3000/fb and $m_{N}\sim 45$ GeV. This represents an improvement of a factor of 2 in sensitivity with respect to earlier work.Comment: 6 pages, 1 figure. In v2: Numerical typo fixed, few clarifications on the simulation and references added. Version accepted for publication in PR

Non-diagonal Charged Lepton Yukawa Matrix: Effects on Neutrino Mixing in Supersymmetry

Generally the diagonalization of the mass matrix of the charged leptons is a part of the neutrino UPMNS matrix. However, usually this contribution is ignored by assuming a diagonal mass matrix for charged leptons. In this letter we test this common assumption in the context of neutrino physics. Our analytical and numerical results for two supersymmetric models reveal that such a simplification is not justified. Especially for the solar and reactor mixing angles important modifications are found.Comment: 22 pages 8 figure

Gravitino Dark Matter in Split Supersymmetry with Bilinear R-Parity Violation

In Split-SUSY with BRpV we show that the Gravitino DM solution is consistent with experimental evidence on its relic density and life time. We arrive at this conclusion by performing a complete numerical and algebraic study of the parameter space, including constraints from the recently determined Higgs mass, updated neutrino physics, and BBN constraints on NLSP decays. The Higgs mass requires a relatively low Split-SUSY mass scale, which is naturally smaller than usual values for reheating temperature, allowing the use of the standard expression for the relic density. We include restrictions from neutrino physics with three generations, and notice that the gravitino decay width depends on the atmospheric neutrino mass scale. We calculate the neutralino decay rate and find it consistent with BBN. We mention some implications on indirect DM searches.Comment: 35 pages, 7 figures. References added, typos corrected and experimental constraints updated. Some clarifications added in Section 2. Version to appear in EPJ

Reconstructing particle masses in events with displaced vertices

We propose a simple way to extract particle masses given a displaced vertex signature in event topologies where two long-lived mother particles decay to visible particles and an invisible daughter. The mother could be either charged or neutral and the neutral daughter could correspond to a dark matter particle in different models. The method allows to extract the parent and daughter masses by using on-shell conditions and energy-momentum conservation, in addition to the displaced decay positions of the parents, which allows to solve the kinematic equations fully on an event-by-event basis. We show the validity of the method by means of simulations including detector effects. If displaced events are seen in discovery searches at the Large Hadron Collider (LHC), this technique can be applied.Comment: 13 pages, 5 figures. v2 includes corrected typos, clarifications on Sec. 3, and extended comments in the Conclusions. Version accepted for publication in JHE

Searching for light long-lived neutralinos at Super-Kamiokande

Light neutralinos could be copiously produced from the decays of mesons generated in cosmic-ray air showers. These neutralinos can be long-lived particles in the context of R-parity violating (RPV) supersymmetric models, implying that they could be capable of reaching the surface of the earth and decay within the instrumental volume of large neutrino detectors. In this letter, we use atmospheric neutrino data from the Super-Kamiokande experiment to derive novel constraints for the RPV couplings involved in the production of long-lived light neutralinos from the decays of charged $D$-mesons and kaons. Our results highlight the potential of neutrino detectors to search for long-lived particles, by demonstrating that it is possible to explore regions of parameter space that are not yet constrained by any fixed-target nor collider experiments.Comment: Version accepted for publication in PRD. 11 pages, 7 figure