13 research outputs found
Sampling the μνSSM in the light of experimental data
No full textTesis doctoral inédita leída en la Universidad Autónoma de Madrid. Facultad de Ciencias, Departamento de Física Teórica. Fecha de Lectura: 10-12-2019The properties and signal rates of the scalar boson discovered by ATLAS and CMS Collaborations at the Large Hadron Collider (LHC) in 2012 indicate that this resonance is compatible with the expectations for the Higgs boson of the Standard Model (SM) of particle physics. Hence, this particle represents the last piece of evidence in favour of the SM in explaining the known elementary particles and their interactions. However, there are relevant questions that cannot be answered in the theoretical framework of the SM, such as for example the origin of the Higgs potential producing the electroweak symmetry breaking (EWSB), the solution of the hierarchy problem, the origin of neutrino masses and mixing angles, the nature of dark matter (DM), the solution to the strong CP problem, the origin of matter anti-matter asymmetry, or how to accommodate the gravitational interaction. From the theoretical viewpoint, many theories have been proposed to address some of these questions. Even though the motivation for each theory might differ, the common point for most of them is that the SM particle content has to be extended and that the new particles are expected to show up at scales not too far from the electroweak (EW) scale. Among a handful of eligible theories beyond the standard model (BSM), EW Supersymmetry (SUSY) has received extensive attention from both theoretical and experimental perspectives over a long period of time. SUSY is a symmetry that provides a connection between fermions and bosons in such a way that for each SM particle there exists a supersymmetric partner (also called sparticle) with the same set of quantum numbers but a half integer spin difference. Thus, SUSY principle allows every SM boson (fermion) to have a supersymmetric partner that is a fermion (boson). As a consequence, SUSY predicts a large number of new particles that could be discovered at the LHC or at the next generation of colliders. Nevertheless, no sparticle has been detected yet despite numerous searches and tremendous efforts of the experimental collaborations. Therefore, the parameter spaces of SUSY models seem to be shrinking considerably. It appears then crucial to conduct thorough studies of the current situation for the different models. In this thesis, we consider the ‘µ from ν’ Supersymmetric Standard Model (µνSSM) as the theoretical model to be analyzed. In addition to the usual advantages of SUSY models, the µνSSM, through the presence of three families of right-handed neutrino superfields can simultaneously solve the µ-problem of the Minimal Supersymmetric Standard Model (MSSM), as well as the ν-problem, being able to reproduce the correct neutrino masses and mixing angles. It can also provide a good candidate for DM, the gravitino.
In SUSY models, the presence of baryon- and lepton-number violating terms predicts too fast proton decay, and usually the R-parity symmetry is used to forbid these terms from appearing in the Lagrangian. This strategy gives rise to the so-called R-parity conserving (RPC) models, such as the MSSM. On the contrary, the µνSSM is an R-parity violating (RPV) model due to the presence of new couplings involving right-handed neutrinos, and therefore violating lepton number (harmless for proton decay). Then, since the lightest supersymmetric particle (LSP) is no longer stable in the µνSSM, it leads to novel signatures at colliders, such as the production of displaced vertices, multileptons or new decay chains. The goal of this thesis is to thoroughly study the parameter space of the µνSSM in the light of current experimental data, using a powerful likelihood data-driven method. In particular, we study the viable regions compatible with current neutrino oscillations and Higgs data, as well as a class of flavor observables. On the one hand, we analyze those regions that can be explored at the current and future runs of the LHC via the extended Higgs sector of the µνSSM, which in general consists of two Higgs doublets mixed with the three families of sneutrinos. Then, we apply this strategy to study the compatibility of the left sneutrino as an interesting LSP candidate in the µνSSM, with current displaced dilepton searches. On the other hand, we also analyze the regions that can explain a long standing puzzle of the SM, namely, the deviation of the measurement of the anomalous magnetic moment of the muon with respect to the theoretical predictio
The new
No full textThe 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, , 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 in agreement with the older BNL result on . The combined result was announced as , yielding a new deviation from the Standard Model prediction of , corresponding to . Using this improved bound we update the analysis in the as presented in Kpatcha et al. (Eur Phys J C 81(2):154. arXiv:1912.0416
Primordial Black Hole Reheating
No full textInternational audiencePost-inflationary reheating phase is usually said to be solely governed by the decay of coherently oscillating inflaton into radiation. In this submission, we explore a new avenue toward reheating through the evaporation of primordial black holes (PBHs). After the inflation, if PBHs form, depending on its initial mass, abundance, and inflaton coupling with the radiation, we found two physically distinct possibilities of reheating the universe. In one possibility, the thermal bath is solely obtained from the decay of PBHs while inflaton plays the role of dominant energy component in the entire process. In the other possibility, we found that PBHs itself dominate the total energy budget of the Universe during the course of evolution, and then its subsequent evaporation leads to radiation dominated universe. Furthermore, we analyze the impact of both monochromatic and extended PBH mass functions and estimate the detailed parameter ranges for which those distinct reheating histories are realized
Primordial black hole versus inflaton
No full textWe compare the dark matter(DM) production processes and its parameters space in the background of reheating obtained from two chief systems in the early Universe: the inflaton and the primordial black holes (PBHs). We concentrated on the mechanism where DMs are universally produced only from the PBH decay and the generation of the standard model plasma from both inflton and PBHs. Whereas the distribution of Primordial Black Holes behaves like dust, the inflaton phenomenology depends strongly on its equation of state after the inflationary phase, which in turn is conditioned by the nature of the potential . Depending upon the initial mass and population of PBHs, a large range of DM mass is shown to be viable if reheating is controlled by PBHs itself. Inflaton-dominated reheating is observed to further widen such possibilities depending on the initial population of black holes and its mass as well as the coupling of the inflaton to the standard model sector.18 pages and 7 figures, published in PR
Primordial Black Hole versus Inflaton: Two Chief Systems of the World
No full textInternational audienceWe compare the dark matter(DM) production processes and its parameters space in the background of reheating obtained from two chief systems in the early Universe: the inflaton and the primordial black holes (PBHs). We concentrated on the mechanism where DMs are universally produced only from the PBH decay and the generation of the standard model plasma from both inflton and PBHs. Whereas the distribution of Primordial Black Holes behaves like dust, the inflaton phenomenology depends strongly on its equation of state after the inflationary phase, which in turn is conditioned by the nature of the potential . Depending upon the initial mass and population of PBHs, a large range of DM mass is shown to be viable if reheating is controlled by PBHs itself. Inflaton-dominated reheating is observed to further widen such possibilities depending on the initial population of black holes and its mass as well as the coupling of the inflaton to the standard model sector
Searching for sbottom LSP at the LHC
No full textAssuming 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 SSM, where the
presence of -parity violating couplings involving right-handed neutrinos
solves simultaneously the -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
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 GeV ( GeV).
The largest possible value found for the decay length is about mm.Comment: Version published in EPJC. Discussion expanded, references added. 28
pages, 4 figures, 3 tables, 1 appendix. Analysis of the stop LSP at the LHC
carried out in arXiv:2111.1321
Impact of Higgs physics on the parameter space of the
No full textGiven 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 SSM. In this model, three families of right-handed neutrino superfields are present in order to solve the problem and simultaneously reproduce neutrino physics. The new couplings and sneutrino vacuum expectation values in the 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 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 decays, while muon is briefly discussed. We find that large regions of the parameter space of the SSM are viable, containing an interesting phenomenology that could be probed at the LHC
Gravitational Wave Production During Reheating: From the Inflaton to Primordial Black Holes
No full textInternational audienceWe calculate the gravitational waves (GWs) produced by primordial black holes (PBHs) in the presence of the inflaton condensate in the early Universe. Combining the GW production from the evaporation process, the gravitational scattering of the inflaton itself, and the density fluctuations due to the inhomogeneous distribution of PBHs, we propose for the first time a complete coherent analysis of the spectrum, revealing three peaks, one for each source. Three frequency ranges ( kHz, GHz, and PHz, respectively) are expected, each giving rise to a similar GW peak amplitude . We also compare our predictions with current and future GWs detection experiments
Searching for gluino LSP at the LHC
No full textAbstract We analyse relevant signals expected at the LHC, assuming that the gluino is the lightest supersymmetric particle (LSP) in the framework of the μ ν 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 μ ν 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
Sampling the mu nu SSM for displaced decays of the tau left sneutrino LSP at the LHC
No full textWithin the framework of the mu nu SSM, a displaced dilepton signal is expected at the LHC from the decay of a tau left sneutrino as the lightest supersymmetric particle (LSP) with a mass in the range 45-100 GeV. We compare the predictions of this scenario with the ATLAS search for long-lived particles using displaced lepton pairs in pp collisions, considering an optimization of the trigger requirements by means of a high level trigger that exploits tracker information. The analysis is carried out in the general case of three families of right-handed neutrino superfields, where all the neutrinos get contributions to their masses at tree level. To analyze the parameter space, we sample the mu nu SSM for a tau left sneutrino LSP with proper decay length c tau>0.1mm 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. The sneutrino is special in the mu nu SSM since its couplings have to be chosen so that the neutrino oscillation data are reproduced. We find that important regions of the parameter space can be probed at the LHC run 3.© The Author(s) 201911Nsciescopu
