The current document summarizes a short-term online internship of eight weeks at the Laboratory of High Energy Physics of the Moscow Institute of Physics and Technology. Bc mesons were reconstructed through the decay channel [ Bc+- to J/psi (to muon+ and muon-) and \pion+- ] in the CMS data collected during the LHC Run 2, a Bc mass of 6272.6(1.1) MeV was found. Alongside the B_c meson search, B+- mesons with a mass of 5278.60(3) MeV were also observed in the data through a similar channel, [ B{+- to J/psi (to muon+ and muon-) and kaon+- ]. Both results present deviations of less than 0.04% from global averages determined by the Particle Data Group collaboration, with the Bc meson mass being compatible with their estimation.

Post-masters internship (8 weeks)

A neutral current fermionic Dark Matter model with the same Lorentz structure of the Standard Model neutral current neutrino was studied in the context of Light Dark Matter candidates. The implications of the new light particle were analyzed for both meson decays and measurements of the neutrino neutral current cross section at the FASERν detector. A minimum value of 8 GeV was found for the energy scale of the dimension-6 effective operator associated to the Dark Matter interactions with the Standard Model particles. However, this lower bound for the energy scale is not relevant for the study of the proposed Dark Matter model, since it is substantially smaller than the top quark mass and than the energies of the pp collisions studied at LHC. It is even too small for a consistent effective theory analysis of the operator under consideration.

Post-masters internship (12 weeks)

A new manifestly Lorentz-invariant action principle for chiral fields, proposed by Ashoke Sen, has been thoroughly studied. The new action is applied in the analysis of chiral 2-form fields in compactified six-dimensional geometries and, then, in five-dimensional reduced spaces. For the free chiral field, the Kaluza-Klein reduced theory features an action describing two free non-chiral fields in 5 dimensions without any additional assumptions, a free vector field and a free 2-form field; the latter being the additional field required for a manifestly Lorentz-invariant formulation. In contrast, the usual formalism of chiral fields requires an assumption for its dimensional reduction and does not generate an action principle, only equations of motion. Nevertheless, both formulations are shown to be equivalent, up to addition of free fields, at the classical level. At last, the compactified chiral free field has been coupled to a dilaton metric and the resulting action is shown to exhibit a similar structure to the compactified chiral free field. In this case, the dilaton couples to all fields of the theory and, as a consequence, the additional free field does not explicitly appears.

Internship of the 2nd year of the Master's degree (4 months)

A simulation for the study of cosmic-ray muon spallation backgrounds in the Super-Kamiokande water Cherenkov detector was developed with the help of the Geant4 toolkit. The simulation was validated against results from a 2014 article of S. W. Li and J. F. Beacom. Though, the validation showed an overall agreement, discrepancies were found in the isotopes yield predictions and in the neutrons behavior. These two facts are linked, as neutrons are the most important particles for isotopes production. A final work was carried out to study the different results from different choices of physics list and from simplifications on the initial muons conditions. The isotopes yields also show significant variations in the case of the different physics lists comparison. In particular, these deviations can be used to evaluate systematic error coming from the physics models used in the simulation. Finally, the simplifications did not have serious implications in the general physics results, only 7 large differences, out of 59 isotopes, were found for the yield predictions. These differences are for very rare events, which still have significant statistical fluctuations for the numbers of events simulated.

Internship of the 1st year of the Master's degree (4 months)