arXiv subjects

Daniel E. López-Fogliani

Publications and source records attributed to Daniel E. López-Fogliani.

8 recordsLinked to original sources

arXiv2025

Searching for a squark LSP of the first two families at the LHC

We analyse relevant signals expected at the LHC for a squark of the first two families as the lightest supersymmetric particle (LSP). The discussion is established in the framework of the $μν$SSM, where the presence of $R$-parity violating couplings involving right-handed neutrinos solves simultaneously the $μ$-problem and the accommodation of neutrino masses and mixing angles. The squarks are pair produced and decay dominantly to a neutrino and a quark. They also have two sub-dominant three body decays to quark, Higgs and neutrino/charged lepton. The decays can be prompt or displaced, depending on the regions of the parameter space of the model. We focus the analyses on squarks of right up-type, right down-type, and left up-type; since squarks of left down-type cannot be the LSP because of D-term contributions. We compare the predictions of these scenarios with ATLAS and CMS searches for prompt and long-lived particles. To analyse the parameter space we sample the $μν$SSM for a squark LSP, paying special attention to reproduce the current experimental data on neutrino and Higgs physics, as well as flavour observables. Because of the contribution of squark-squark final states to the production cross section, the results depend on the squark family. In particular, for a right strange squark LSP, the lower limit on the mass is $1646$ GeV, corresponding to an upper limit on the decay length of $54.7$ mm, and for a right (left) scharm LSP, the limits are $1625$ ($1357$) GeV and $13.4$ ($1.9$) mm. However, the first family of squarks as LSP turns out to be excluded, unless the gluino is heavier than $7$ TeV, which produces a limit on the squark mass of $1800$ GeV.

hep-ph↗

arXiv2025

Searching for Gluino LSP at the LHC

We analyse relevant signals expected at the LHC, assuming that the gluino is the lightest supersymmetric particle (LSP) in the framework of the $μν$SSM. In this $R$-parity violating model, the presence of couplings involving right-handed neutrinos solves simultaneously the $μ$ problem and the accommodations of neutrino masses and mixing angles. We study gluino pair production in quark-antiquark and gluon-gluon collisions. The main decay channels for the gluino LSP are the three-body decays to two quarks and a lepton or a neutrino. In both cases, the leading channels occur for the third family of quarks. We compare the predictions of this scenario with LHC searches for prompt and long-lived particles. To analyse the parameter space we sample the $μν$SSM for a gluino LSP, paying special attention to reproduce the current experimental data on neutrino and Higgs physics, as well as flavour observables. Our results imply a lower limit on the mass of the gluino LSP of about 2600 GeV, and an upper limit for the decay length of about 6 cm.

hep-ph↗

arXiv2024

Searching for sbottom LSP at the LHC

Assuming that the sbottom is the lightest supersymmetric particle (LSP), we carry out an analysis of the relevant signals expected at the LHC. The discussion is established in the framework of the $μν$SSM, where the presence of $R$-parity violating couplings involving right-handed neutrinos solves simultaneously the $μ$-problem and the accommodation of neutrino masses and mixing angles. The sbottoms are pair produced at the LHC, decaying to a lepton and a top quark or a neutrino and a bottom quark. The decays can be prompt or displaced, depending on the regions of the parameter space of the model. We focus the analysis on the right sbottom LSP, since the left sbottom is typically heavier than the left stop because of the D-term contribution. We compare the predictions of this scenario with ATLAS and CMS searches for prompt and long-lived particles. To analyze the parameter space we sample the $μν$SSM for a right sbottom LSP, paying special attention to reproduce the current experimental data on neutrino and Higgs physics, as well as flavor observables. For displaced (prompt) decays, our results translate into lower limits on the mass of the right sbottom LSP of about $1041$ GeV ($1070$ GeV). The largest possible value found for the decay length is about $3.5$ mm.

hep-ph↗

arXiv2022

Searching for stop LSP at the LHC

We analyze relevant signals expected at the LHC for a stop as the lightest supersymmetric particle (LSP). The discussion is carried out in the framework of the $μν$SSM, where the presence of $R$-parity violating couplings involving right-handed neutrinos solves the $μ$-problem and reproduces neutrino data. The stops are pair produced at the LHC, decaying with displaced vertices to a lepton and a bottom quark or a neutrino and a top quark. We compare the predictions of this scenario with ATLAS and CMS searches for long-lived particles. To analyze the parameter space we sample the $μν$SSM for a stop LSP using a likelihood data-driven method, and paying special attention to reproduce the current experimental data on neutrino and Higgs physics, as well as flavor observables. Our results translate into a lower limit on the mass of the left (right) stop LSP of 1068 GeV (1341 GeV), corresponding to a decay length of 1.86 mm (6.61 mm).

hep-ph↗

arXiv2021

The new $(g-2)_μ$ result and the $μν$SSM

The $μν$SSM is a highly predictive alternative model to the MSSM. In particular, the electroweak sector of the model can explain the longstanding discrepancy between the experimental result for the anomalous magnetic moment of the muon, $(g-2)_μ$, and its Standard Model prediction, while being in agreement with all other theoretical and experimental constraints. The recently published MUON G-2 result is within $0.8\,σ$ in agreement with the older BNL result on $(g-2)_μ$. The combined result was announced as $a_μ^{\rm exp} = (11659206.1 \pm 4.1) \times 10^{-10}$, yielding a new deviation from the Standard Model prediction of $Δa_μ= (25.1 \pm 5.9) \times 10^{-10}$, corresponding to $4.2\,σ$. Using this improved bound we update the analysis in the $μν$SSM as presented in Ref. [1] and set new limits on the allowed parameters space of the electroweak sector of the model. We conclude that significant regions of the model can explain the new $(g-2)_μ$ data.

hep-ph↗

arXiv2020

Impact of Higgs physics on the parameter space of the $μν$SSM

Given the increasing number of experimental data, together with the precise measurement of the properties of the Higgs boson at the LHC, the parameter space of supersymmetric models starts to be constrained. We carry out a detailed analysis of this issue in the framework of the $μν$SSM. In this model, three families of right-handed neutrino superfields are present in order to solve the $μ$ problem and simultaneously reproduce neutrino physics. The new couplings and sneutrino vacuum expectation values in the $μν$SSM induce new mixing of states, and, in particular, the three right sneutrinos can be substantially mixed with the neutral Higgses. After diagonalization, the masses of the corresponding three singlet-like eigenstates can be smaller or larger than the mass of the Higgs, or even degenerated with it. We analyze whether these situations are still compatible with the experimental results. To address it we scan the parameter space of the Higgs sector of the model. In particular, we sample the $μν$SSM using a powerful likelihood data-driven method, paying special attention to satisfy the constraints coming from Higgs sector measurements/limits (using HiggsBounds and HiggsSignals), as well as a class of flavor observables such as $B$ and $μ$ decays, while muon $g-2$ is briefly discussed. We find that large regions of the parameter space of the $μν$SSM are viable, containing an interesting phenomenology that could be probed at the LHC.

hep-ph↗

arXiv2011

Next-to-Minimal Supersymmetric Model Higgs Scenarios for Partially Universal GUT Scale Boundary Conditions

We examine the extent to which it is possible to realize the NMSSM "ideal Higgs" models espoused in several papers by Gunion et al in the context of partially universal GUT scale boundary conditions. To this end we use the powerful methodology of nested sampling. We pay particular attention to whether ideal-Higgs-like points not only pass LEP constraints but are also acceptable in terms of the numerous constraints now available, including those from the Tevatron and $B$-factory data, $(g-2)_μ$ and the relic density $Ωh^2$. In general for this particular methodology and range of parameters chosen, very few points corresponding to said previous studies were found, and those that were found were at best $2σ$ away from the preferred relic density value. Instead, there exist a class of points, which combine a mostly singlet-like Higgs with a mostly singlino-like neutralino coannihilating with the lightest stau, that are able to effectively pass all implemented constraints in the region $80<m_h<100$. It seems that the spin-independent direct detection cross section acts as a key discriminator between ideal Higgs points and the hard to detect singlino-like points.

hep-ph↗

arXiv2011

Is light neutralino as dark matter still viable?

Motivated by the recent re-confirmation by CoGENT of the low-energy excess of events observed last year, and the recent improved limits from the XENON-100 experiment that are in contention with the CoGENT data, we re-examine the low mass neutralino region of the Minimal Supersymmetric Standard Model and of the Next-to-Minimal Supersymmetric Standard Model, both without assuming gaugino mass unification. We make several focused scans for each model, determining conservative constraints on input parameters. We then determine how these constraints are made increasingly stringent as we re-invoke our experimental constraints involving the dark matter relic abundance, collider constraints from LEP and the Tevatron, and then from flavour physics, as a series of successive 2 sigma hard cuts. We find that for both models, when all relevant constraints are applied in this fashion, we do not generate neutralino LSPs that possess a spin-independent scattering cross section in excess of 10^-5 pb and a mass ~7 GeV < m_chi < ~9 GeV that is necessary in order to explain the CoGENT observations.

astro-ph.CO↗