Search for New Physics in the associated production channel of a Higgs and a W boson at ATLAS

DOMAIN: Particle and Astroparticle Physics and associated scientific domains

SUPERVISOR: Patricia Conde Muino



HOST INSTITUTION: Laboratório de Instrumentação e Física Experimental de Partículas

DEGREE INSTITUTION: Universidade de Lisboa



Since the discovery of the Higgs boson, the precise measurement of its properties has become a fundamental part of the ATLAS Physics programme. The recent announcement of the observation of the Higgs decay to b-quarks and the associated production of the Higgs with top quarks, done by the ATLAS and CMS collaborations at CERN, probe directly the coupling of the Higgs to quarks and constituted an important step forward in the understanding of the Higgs mechanism. As the LHC continues to take data and more luminosity is accumulated, more precise measurements of the Higgs boson properties are possible, opening the door to search for new physics in the Higgs sector. Along this line of research, the study of the high transverse momentum (high-pT) Higgs production, in the associated production channel with a W boson, is sensitive to new physics in the hWW vertex and constitutes one of the measurements to be done in the near future by the ATLAS collaboration. The main objective of this research project is to search for anomalous Spin and CP components of the interaction vertex between the Higgs and the W bosons. The measurement will be done in the associated production channel of the Higgs with a W, when the W decays to leptons (𝓵𝜈) and the Higgs decays to b-quark pairs. Being affected by different systematics and kinematic constraints with respect to the h→WW decay, this channel allows probing the spin and CP properties of the hWW vertex in a complementary way to the studies done so far. The work plan foresees the identification of the most sensitive observables for anomalous couplings, followed by the analysis of the full Run-2 ATLAS dataset. The results will be interpreted in the framework of the Effective Field Theory (EFT) approach. At the same time the results will be interpreted in terms of extensions of the Standard Model with extra sources of CP-violation. The student will be part of the ATLAS team participating in this analysis. The work will be developed in an international collaboration and the results obtained will be presented at CERN. The student is expected to contribute in addition to the data taking and detector operation activities, both at CERN and at LIP. This PhD grant foresees a two-year stay at CERN to develop the proposed research project.