Search

We investigate the possibility that right-handed (RH) sneutrinos and gravitinos can coexist and explain the dark matter (DM) problem. We compare extensions of the minimal supersymmetric standard model (MSSM) and the next-to-MSSM (NMSSM) adding RH neutrinos superfields, with special emphasis on the latter. If the gravitino is the lightest supersymmetric particle (LSP) and the RH sneutrino the next-to-LSP (NLSP), the heavier particle decays to the former plus left-handed (LH) neutrinos through the mixing between the scalar partners of the LH and RH neutrinos. However, the interaction is suppressed by the Planck mass, and if the LH-RH sneutrino mixing parameter is small, $\ll O(10^{-2})$, a long-lived RH sneutrino NLSP is possible even surpassing the age of the Universe. As a byproduct, the NLSP to LSP decay produces monochromatic neutrinos in the ballpark of current and planned neutrino telescopes like Super-Kamiokande, IceCube and Antares that we use to set constraints and show prospects of detection. In the NMSSM+RHN, assuming a gluino mass parameter $M_3 = 3$ TeV we found the following lower limits for the gravitino mass $m_{3/2} \gtrsim 1-600$ GeV and the reheating temperature $T_R \gtrsim 10^5 - 3 \times 10^7$ GeV, for $m_{\tilde{\nu}_R} \sim 10-800$ GeV. If we take $M_3=10$ TeV, then the limits on $T_R$ are relaxed by one order of magnitude., Comment: Discussions improved and expanded, version published in JCAP, 35 pages, 7 figures, 3 tables

Machine-Learned Likelihoods (MLL) is a method that, by combining modern machine-learning classification techniques with likelihood-based inference tests, allows to estimate the experimental sensitivity of high-dimensional data sets. We extend the MLL method by including the exclusion hypothesis tests and show that the addition of Kernel Density Estimators avoids the need to bin the classifier output in order to extract the resulting one-dimensional signal and background probability density functions. We first test our method on toy models generated with multivariate Gaussian distributions, where the true probability distribution functions are known. We then apply it to a case of interest in the search for new physics at the HL-LHC, in which a $Z^\prime$ boson decays into lepton pairs, comparing the performance of our method for estimating 95\% CL exclusion limits to the results obtained applying a binned likelihood to the machine-learning classifier output., Comment: 14 pages, 3 figures. MLL+KDE code will be available from https://github.com/AndresDanielPerez

To elucidate the composition of dark matter (DM) is one of the most important open questions in particle and astroparticle phenomenology. Within the framework of minimal supersymmetric extensions of the standard model of fundamental particles, the `mu-from-nu supersymmetric standard model', $\mu\nu$SSM, solves the $\mu$-problem and reproduces neutrino data, only adding couplings involving right-handed neutrinos. In this context, the supersymmetric partner of the graviton, known as gravitino, becomes a natural DM candidate. Working in the mentioned model, in this thesis we have analyzed the detection of gamma-ray signals arising from decaying gravitino DM considering experiments such as $\textit{Fermi}$-LAT. For this purpose all gravitino decays have been taken into account, complementing previous works. The possibility of an upcoming new generation of gamma-ray detectors has motivated the inclusion of axino, the supersymmetric partner of the axion, as a DM candidate. In this thesis, axino DM has been analyzed in the context of the $\mu\nu$SSM for the first time. Finally, scenarios with multicomponent DM have been studied, focusing on gravitinos and axinos coexisting as DM constituents. This novel scenario includes two very different cases with distinctive features: axino lighter than gravitino and vice versa. Considering the sensitivity of future MeV-GeV gamma-ray telescopes, axino and gravitino prospects of detection were analyzed in the mixed scenarios mentioned previously. In some parameter space regions, both candidates can produce a signal, therefore a double-line feature arises as a smoking gun that would uncover the DM composition., Comment: PhD thesis, 187 pages, in Spanish (Abstract in English). Based on arXiv:1608.08640, arXiv:1911.03191, and arXiv:1911.08550

To elucidate the composition of dark matter (DM) is one of the most important open questions in particle and astroparticle phenomenology. Within the framework of minimal supersymmetric extensions of the standard model of fundamental particles, the `mu-from-nu supersymmetric standard model', $����$SSM, solves the $��$-problem and reproduces neutrino data, only adding couplings involving right-handed neutrinos. In this context, the supersymmetric partner of the graviton, known as gravitino, becomes a natural DM candidate. Working in the mentioned model, in this thesis we have analyzed the detection of gamma-ray signals arising from decaying gravitino DM considering experiments such as $\textit{Fermi}$-LAT. For this purpose all gravitino decays have been taken into account, complementing previous works. The possibility of an upcoming new generation of gamma-ray detectors has motivated the inclusion of axino, the supersymmetric partner of the axion, as a DM candidate. In this thesis, axino DM has been analyzed in the context of the $����$SSM for the first time. Finally, scenarios with multicomponent DM have been studied, focusing on gravitinos and axinos coexisting as DM constituents. This novel scenario includes two very different cases with distinctive features: axino lighter than gravitino and vice versa. Considering the sensitivity of future MeV-GeV gamma-ray telescopes, axino and gravitino prospects of detection were analyzed in the mixed scenarios mentioned previously. In some parameter space regions, both candidates can produce a signal, therefore a double-line feature arises as a smoking gun that would uncover the DM composition., PhD thesis, 187 pages, in Spanish (Abstract in English). Based on arXiv:1608.08640, arXiv:1911.03191, and arXiv:1911.08550

In $R$-parity violating supersymmetry, the gravitino as the lightest supersymmetric particle (LSP) is a good candidate for dark matter, with the interesting characteristic to be detectable through $\gamma$-ray telescopes. We extend this analysis considering an axino next-to-LSP (NLSP) as a coexisting dark matter particle contributing with a detectable signal in the $\gamma$-ray spectrum. The analysis is carried out in the framework of the $\mu\nu$SSM, which solves the $\mu$ problem reproducing simultaneously neutrino data only with the addition of right-handed neutrinos. We find that important regions of the parameter space can be tested by future MeV-GeV $\gamma$-ray telescopes through the line signal coming from the decay of the axino NLSP into photon-neutrino. In a special region, a double-line signal from axino NLSP and gravitino LSP is possible with both contributions detectable., Comment: Version published in Astroparticle Physics. Discussions expanded, appendix and references added, 23 pages, 4 figures. The analysis of the opposite case (axino LSP with gravitino NLSP) was carried out in arXiv:1911.03191

In $R$-parity violating supersymmetry, the gravitino as the lightest supersymmetric particle (LSP) is a good candidate for dark matter, with the interesting characteristic to be detectable through $��$-ray telescopes. We extend this analysis considering an axino next-to-LSP (NLSP) as a coexisting dark matter particle contributing with a detectable signal in the $��$-ray spectrum. The analysis is carried out in the framework of the $����$SSM, which solves the $��$ problem reproducing simultaneously neutrino data only with the addition of right-handed neutrinos. We find that important regions of the parameter space can be tested by future MeV-GeV $��$-ray telescopes through the line signal coming from the decay of the axino NLSP into photon-neutrino. In a special region, a double-line signal from axino NLSP and gravitino LSP is possible with both contributions detectable., Version published in Astroparticle Physics. Discussions expanded, appendix and references added, 23 pages, 4 figures. The analysis of the opposite case (axino LSP with gravitino NLSP) was carried out in arXiv:1911.03191

Axino and gravitino are promising candidates to solve the dark matter (DM) problem in the framework of supersymmetry. In this work, we assume that the axino is the lightest supersymmetric particle (LSP), and therefore contributes to DM. In the case of R-parity violating models, the axino can decay into a neutrino-photon pair with a lifetime much longer than the age of the Universe, yielding a potentially detectable signal. Interestingly, a gravitino next-to-LSP (NLSP) can live enough as to contribute to the relic density. We study both scenarios, only axino LSP as DM, and axino LSP with gravitino NLSP as DM. We carry out the analysis in the context of the $����$SSM, which solves the $��$ problem and reproduces neutrino data, only adding couplings involving right-handed neutrinos. In particular, we perform a complete analysis of the relevant parameter space of the model considering constraints from neutrino physics, cosmological observations, and $��$-ray detection. We find that the axino or the gravitino can produce a signal detectable by future MeV-GeV $��$-ray telescopes. In addition, in a parameter region where we get a well-tempered mixture of both particles, a double-line signal arises as a smoking gun., Version published in JCAP, discussions expanded, references added, 27 pages, 6 figures

The $����$SSM solves the $��$ problem of supersymmetric models and reproduces neutrino data, simply using couplings with right-handed neutrinos $��$'s. Given that these couplings break explicitly $R$ parity, the gravitino is a natural candidate for decaying dark matter in the $����$SSM. In this work we carry out a complete analysis of the detection of $����$SSM gravitino dark matter through $��$-ray observations. In addition to the two-body decay producing a sharp line, we include in the analysis the three-body decays producing a smooth spectral signature. We perform first a deep exploration of the low-energy parameter space of the $����$SSM taking into account that neutrino data must be reproduced. Then, we compare the $��$-ray fluxes predicted by the model with Fermi-LAT observations. In particular, with the 95$\%$ CL upper limits on the total diffuse extragalactic $��$-ray background using 50 months of data, together with the upper limits on line emission from an updated analysis using 69.9 months of data. For standard values of bino and wino masses, gravitinos with masses larger than about 4 GeV, or lifetimes smaller than $10^{28}$ s, produce too large fluxes and are excluded as dark matter candidates. However, when limiting scenarios with large and close values of the gaugino masses are considered, the constraints turn out to be less stringent, excluding masses larger than 17 GeV and lifetimes smaller than $4\times 10^{25}$ s., Minor changes, references added, version published in JCAP. 23 pages, 7 figures, 3 tables