Collider and gravitational echoes of Full Unification with deep-learning

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Publications

Deep learning searches for vector-like leptons at the LHC and electron/muon colliders

Publication . Morais, António P.; Onofre, António; Freitas, Felipe F.; Gonçalves, João; Pasechnik, Roman; Santos, Rui

he discovery potential of both singlet and doublet vector-like leptons (VLLs) at the Large Hadron Collider (LHC) as well as at the not-so-far future muon and electron machines is explored. The focus is on a single production channel for LHC direct searches while double production signatures are proposed for the leptonic colliders. A Deep Learning algorithm to determine the discovery (or exclusion) statistical significance at the LHC is employed. While doublet VLLs can be probed up to masses of 1 TeV, their singlet counterparts have very low cross sections and can hardly be tested beyond a few hundreds of GeV at the LHC. This motivates a physics-case analysis in the context of leptonic colliders where one obtains larger cross sections in VLL double production channels, allowing to probe higher mass regimes otherwise inaccessible even to the LHC high-luminosity upgrade.

2023Journal article

Open access

Search for an invisible scalar in tt¯ final states at the LHC

Publication . Azevedo, Duarte; Capucha, Rodrigo; Chaves, Pedro; Martins, João Bravo; Onofre, A.; Santos, Rui

We use the current tt¯ experimental analysis to look for Dark Matter (DM) particles hidden in the final state. We present a phenomenological study where we successfully perform the reconstruction of a tt¯ system in the presence of a scalar mediator Y 0, that couples to both Standard Model (SM) and to DM particles. We use a MadGraph5_aMC@NLO simplified DM model, where signal samples of pp → tt¯ Y 0 are generated at the Large Hadron Collider (LHC) with both Charge-Parity (CP) -even and CP-odd couplings of Y 0 to the top quarks. Different mass scales for the Y 0 mediator are considered, from the low mass region (~ 0 GeV) to masses close to the Higgs boson mass (125 GeV). The dileptonic final states of the tt¯ system were used in our analysis. The reconstruction of the tt¯ system is done with a kinematic fit, without reconstructing the mediator. All relevant SM backgrounds for the dileptonic tt¯ search at the LHC are considered. Furthermore, CP angular observables were used to probe the CP-nature of the coupling between the mediator and top-quarks, which allowed to set confidence level (CL) limits for those Yukawa couplings as a function of the mediator mass.

2023Journal article

Open access

Precision muon-related observables as a tool to constrain new physics models

Publication . Lourenço, Gabriel; Milagre, André; Santos, Rui; Silva, Joao

We propose a set of precision muon-related observables that serve as a tool to constrain new physics models. Using LEP's precision measurements on the Z-boson pole, we derive bounds on the new physics quantum contributions to the decay Z -> mu+mu(-). We show that the new precision observables have a real impact on two specific models that solve the g - 2 anomaly and provide a sound dark matter candidate.

2024-07Journal article

Restricted access