M. Missiroli

Phantom limb syndrome (PLS) comprises various disturbances, including pain in the missing limb and phantom sensations. This study is about the successful treatment of a PLS patient by prolonged infusion of local anesthetic through a perineural catheter. A 45-year-old man came to the Rizzoli Orthopedic Institute (Bologna, Italy) complaining of a painful right leg after trauma. Complex regional pain syndrome (CRPS) type II was diagnosed. Therapy with tricyclics, gabapentin, and spinal infusion of morphine was started. After 4 years of treatment, infection led to the need for right below-the-knee amputation. After amputation, PLS appeared immediately and was not responsive to pharmacological treatment. At day II, a perineural sciatic catheter was positioned and 0.5% ropivacaine infusion with an elastomeric pump at 5 mL/h was started. The infusion was temporarily discontinued every week to evaluate the PLS. After 7 days, a 30% reduction in pain was observed, increased to 60% after 14 days, and disappeared completely after 21 days, leaving only the phantom limb sensations. After 28 days of continuous infusion, the phantom limb sensations had also disappeared. The perineural catheter was removed after 48 hours without perineural infusion. The patient was weaned from morphine over 150 days. Follow-ups at 6, 12, 24, and 36 months confirmed that the PLS did not reappear. The results are limited to one patient but are encouraging, particularly due to the relevance of the pathology and the poor results of conventional treatments. More cases are obviously needed to support the efficacy of this therapy.

Abstract To cope with the challenges posed by the High-Luminosity LHC, the CMS experiment will feature a new silicon tracker. The modules of the upgraded inner tracker are hybrid silicon pixel modules based on a new readout chip, developed by the RD53 collaboration. Compared to the readout chip of the current pixel detector, the RD53 chip is capable of sustaining higher hit rates and radiation levels, as well as enabling the use of serial-powering chains. The qualification of the latest version of this chip (RD53B) is underway, and it will lead to the final version of the readout chip to be used in the CMS inner tracker during the HL-LHC. First digital modules featuring the RD53B-CMS chip have been assembled in 2022 (the term digital module denotes a module assembly with readout chips, but without sensors bonded to them). This contribution presents results of tests on these first prototype modules.

We present the first results on searches for new massive resonances decaying to a top-antitop quark ($t\bar{t}$) pair with the CMS detector at the LHC in proton-proton collisions with a center of mass energy of $\sqrt{s}=13~\mathrm{TeV}$. The data set considered corresponds to an integrated luminosity of $2.6~\mathrm{fb}^{-1}$ recorded during the the first year of the LHC Run-2. Searches are performed by measuring the invariant mass distribution of the $t\bar{t}$ system in semileptonic and fully-hadronic final states. Dedicated techniques are used to identify the decay of highly-boosted top quarks in order to maximize the analyses' sensitivity for $t\bar{t}$ resonances with a mass above the TeV scale. No significant excess is observed in the data compared to the expected SM background and exclusion limits are set on the cross section of a $t\bar{t}$ resonance in various new physics scenarios.

This thesis presents the results of two searches for a top-antitop quark (ttbar) resonance in semileptonic final states using data collected by the Compact Muon Solenoid (CMS) experiment at the CERN Large Hadron Collider (LHC). Evidence of resonant ttbar production would represent a clear sign of new physics beyond the Standard Model of particle physics. The first search is based on the full data set recorded by the CMS experiment in proton-proton (pp) collisions at a center-of-mass energy of sqrt(s)=8 TeV during the LHC Run-1, for a total integrated luminosity of 19.7 fb-1. The second search considers 2.6 fb-1 of pp collisions data recorded by the CMS experiment in the first year of the LHC Run-2 (2015) at the higher center-of-mass energy of sqrt(s)=13 TeV. Both analyses make use of state-of-the-art techniques for the identification of top quarks produced with large transverse momentum. This approach maximizes the sensitivity of the analyses for high-mass X->ttbar resonances (M_X > 1 TeV), which are characterized by the production of an increasing fraction of top quarks in the boosted regime. The thesis also presents a set of studies on the use of the angular observables of the ttbar system and the treatment of interference effects in X->ttbar searches. No evidence for resonant ttbar production is found in the data sets considered and the invariant mass spectrum of the reconstructed ttbar system is used to set upper limits on the production cross section of a X->ttbar resonance in various new physics models.