[Aperitivo Scientifico] A state-of-the-art measurement of the Higgs boson mass using diphoton decays with the CMS experiment

by Fabio Iemmi (B)

Tuesday May 26, 2026, 11:00 AM → 12:00 PM Europe/Rome

IR-1A (DIFA Irnerio (Bologna))

The mass of the Higgs boson (MH) is a fundamental parameter of the Standard Model (SM) of particle physics. Although MH is not predicted by the theory, many of the Higgs boson’s properties — such as its couplings, branching fractions, and natural width — are determined once the mass is measured. In addition, the value of MH is related to the stability of the electroweak vacuum, with important cosmological implications, and serves as an input to global electroweak fits that provide over-constrained consistency tests of the SM. These considerations motivate high-precision measurements of this key parameter.

We present a state-of-the-art measurement of the Higgs boson mass using decays to pairs of photons collected by the CMS experiment during LHC Run 2. Special attention is given to the experimental techniques used to calibrate the photon energy scale and to assess and reduce systematic uncertainties, resulting in a factor-of-two improvement in total uncertainty compared to previous CMS measurements.

Finally, we discuss the expected precision from a combined analysis of all available measurements from the ATLAS and CMS Collaborations, and outline prospects for future Higgs boson mass measurements.

Il seminario illustrerà le potenzialità di fisica e gli obiettivi dell'esperimento, riporterà una breve panoramica dei vari sistemi e sottosistemi che lo compongono e ne descriverà le prestazioni iniziali.
Infine, verrà presentato il primo risultato sull'oscillazione relativo ai valori dei cosiddetti parametri di oscillazione “solare”, Δm221 e sin2θ12.

Seminar_MH_INFNUniBO_Iemmi-1.pdf