Signatures of SUSY Dark Matter at the LHC and in the Spectra of Cosmic Rays

TL;DR

This thesis explores supersymmetry detection at the LHC and cosmic ray spectra, introducing a novel positron identification method that extends sensitivity and suggests possible positron excesses hinting at dark matter signals.

Contribution

It presents a new approach for identifying positrons via bremsstrahlung conversion, enhancing cosmic ray measurement sensitivity and providing evidence for positron excesses potentially linked to dark matter.

Findings

Bremsstrahlung method suppresses proton background by over 3 million times.

Positron measurement sensitivity extends up to 50 GeV/c.

Indication of positron overabundance above 8 GeV/c, supporting previous hints.

Abstract

This thesis discusses the search for supersymmetry at the future Large Hadron Collider (LHC) and the ongoing construction of one of the four large LHC experiments, the Compact Muon Solenoid (CMS), and focuses on the detection of signals from the annihilation of supersymmetric dark matter in the spectra of cosmic rays. Measurements of cosmic ray antiparticles, such as positrons, can impose strong constraints on the nature of new physics beyond the Standard Model. However, cosmic ray positron measurements are experimentally very challenging due to the vast proton background. A novel approach of positron identification with the space-borne AMS-01 experiment, namely through the detection of bremsstrahlung conversion in a silicon microstrip detector, is introduced. Bremsstrahlung from protons is suppressed by a factor of more than 3*10^6 with respect to positrons. The results of the positron measurement show that the bremsstrahlung approach extends the sensitivity range of AMS-01 to positron momenta up to 50 GeV/c, which is far beyond the original scope of the experiment. At momenta above 8 GeV/c there is indication for a positron overabundance with respect to model predictions for purely secondary positron production. Therefore, the AMS-01 data lend further weight to the hints of a positron overabundance seen in the data from earlier experiments. The positron fraction measurements from the most recent experiments are combined with the results of this analysis, giving the most precise positron fraction data yet available.