Books

The coherent synthesis of pulses from Optical Parametric Amplifiers (OPAs) offers the possibility to realize field-controlled electromagnetic waveforms with sub-cycle durations, widely scalable in energy and spectral bandwidth.Here we demonstrate a fully functional prototype of a mJ-level two channel parametric waveform synthesizer, which is ready to be upgraded to three channels. The synthesized field, whose bandwidth covers more than 2 octaves, from ~500 nm to ~2200 nm, can be compressed to a non-sinusoidal sub-cycle waveform close to the transform-limit.The long term stable operation of such a complex laser source is achieved, for the first time, by means of a sophisticated optical and mechanical design of the whole OPA system, along with targeted improvements made to the commercial pump laser.A new seeding scheme based on multiple supercontinua, further scalable to the mid-IR, leads to excellent phase stability among the different OPA channels and to a simplified dispersion management scheme.A detailed study, both theoretical and experimental, of the couplings among different pulse parameters during the parametric amplification, unveiled novel details of the Carrier-Envelope-Phase (CEP) stabilization process via OPA, and guided the design of the CEP-controlled seeding front-end.A simplified two-dimensional spectral shearing interferometry setup, where the ancillary pulses are obtained by spectral filtering the pump pulses, has been developed to easily characterize the spectral phase of the ultrabroadband pulses from each channel, overcoming the limitation of second-harmonic-based methods.Furthermore, ad-hoc nonlinear optical techniques have been deployed to observe the most relevant synthesis parameters such as the CEP of the seeding pulses and the relative phase among the different channels outputs. [...]

This thesis is focused on the search for pair production of the supersymmetric $\tau$ lepton partners within the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC). The search is performed using the data collected at a center-of-mass-energy $\sqrt{s} = 13$ TeV with the CMS detector in the years 2016-2017.One of the most popular extensions of the Standard Model (SM) is supersymmetry (SUSY). [...]

Plasma wakefields are a promising approach for the acceleration of electrons with ultrahigh (10 to 100 GV/m) electric fields. Nowadays, high-intensity laser pulses are routinely utilized to excite these large-amplitude plasma waves. [...]

In this thesis we discuss modern mathematical tools for the perturbative analysis of supersymmetric Yang–Mills theories (abbreviated SYM). We apply contemporary and traditional computational techniques to two kind of problems. [...]

This work addresses the measurements and phenomenology of the azimuthal separation $\Delta\phi_{12}$ between the jets with the largest transverse momenta $(p_T)$ in multi-jet event topologies. The measurements are based on proton-proton collision data at the center-of-mass energy of 13 TeV recorded by the Compact Muon Solenoid (CMS) experiment in 2016, and correspond to an integrated luminosity of 35.9 fb$^{−1}$ [...]

This thesis presents the measurement of associated production of a W$^±$ boson and a charm quark (W + c) in proton-proton collisions at a center-of-mass energy of 13 TeV. The data used in this analysis has been recorded by the CMS experiment at the CERN LHC and corresponds to an integrated luminosity of 35.7 fb$^{-1}$ . [...]

In the first part of this thesis we investigate the viability of a class of models for de Sitter (dS) vacua in string theory, due to Kachru, Kallosh, Linde and Trivedi (KKLT). We start by explaining why the success or failure of such models is sensitive to a large number of Planck suppressed operators, and collect circumstantial evidence that this UV sensitivity cannot be evaded with delicately engineered models such as the Kallosh-Linde (KL) racetrack due to a generic conflict with the weak gravity conjecture (WGC) for axions. [...]

This thesis presents the measurement of the coupling strength of the 125 GeV Higgsboson toτleptons. The measurement is performed on proton-proton collision data at acentre-of-mass energy of 13 TeV, collected by the CMS experiment at the LHC in the year2016, and corresponding to an integrated luminosity of 35.9 fb−1. [...]

Several tools for quench localization at Superconducting Radio Frequency cavities exist. One of these techniques uses the excitation of temperature waves in liquid Helium below the lambda point. [...]