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Collider Cross Talk
HBSM -> gamma gamma (95 GeV) - excess?
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Europe/Zurich
4/2-011 - TH common room (CERN)
Description
Abstract:
Numerous theoretical BSM models permit the existence of additional Higgs bosons having masses both above and below that of the 125 GeV Higgs boson discovered so far. We will set the stage by giving a brief theoretical introduction about the impact of the LHC low-mass H → gamma gamma searches on models with extended Higgs sectors. This discussion will put into perspective the sensitivity of the diphoton channel to Higgs-like particles in comparison to earlier searches at LEP and the LHC in different final states.
We then provide an overview of the latest Run-2 ATLAS and CMS searches in the low mass range (~70 - 110 GeV), discussing the experimental strengths and principal challenges associated with a search in the diphoton decay channel. This discussion will cover the multi-variate analysis techniques used by both analyses to mitigate background processes and classify events, thus improving the sensitivity to physics beyond the Standard Model. The results of these analyses are then presented, with the CMS experiment reporting an observed excess with respect to the standard model prediction at 95.4 GeV with a local (global) significance of 2.9 (1.3) standard deviations. ATLAS reports a similar excess of events at 95.4 GeV with a local significance of 1.7 standard deviations. We then conclude with a short summary of possible model interpretations of these excesses.
Thomas Biekötter is a postdoctoral researcher at the Institute for Theoretical Physics at the Karlsruhe Institute of Technology. In 2019 he earned his PhD at the Instituto de Física Teórica in Madrid, working on Supersymmetry and the phenomenology of models with extended Higgs sectors at the LHC. After defending his thesis, Thomas moved for the first postdoc position to DESY, until 2022, before moving to Karlsruhe for the second postdoc position. In recent years, Thomas' research focuses on the interplay between the LHC and gravitational-wave detectors and new ways to shed light on the physics underlying electroweak symmetry breaking and possible connection to new physics. Triggered by the observation of the 95 GeV diphoton excesses by CMS, in combination with additional excesses observed at this mass at LEP and in ditau events at the LHC, Thomas has published several works on the possible interpretation of the excesses in models with extended Higgs sectors and implications for future searches.
Christopher Hayes is a postdoctoral researcher with the University of Michigan and a member of the ATLAS Collaboration whose research focuses on searches for beyond the Standard Model physics, typically related to BSM Higgs bosons. Chris attended Stony Brook University and received his PhD in 2019 on searches for exotic decays of the 125 GeV Higgs boson in the 2b2mu final state. After joining the University of Michigan, he has led several searches for BSM Higgs bosons in the diphoton final state and served as co-convener of the Higgs and Light Resonance Searches (HLRS) subgroup in ATLAS’s HDBS group from October 2020 – October 2022.
Susan Gascon-Shotkin is a CMS experimental physicist. She received her PhD from MIT on neutralino searches with the L3 experiment, then turned to Higgs boson searches involving final-state tau leptons as a postdoc on OPAL. She then joined the CMS group at IP2I Lyon (formerly IPN Lyon), working on the ECAL construction and commissioning, becoming a full professor at the Université Claude Bernard Lyon 1 in 2001. Her research team participated in photon commissioning, the first CMS direct photon measurements, and the discovery of the 125 GeV Higgs boson via the diphoton decay channel. Since 2013 she has co-coordinated CMS searches for low-mass Higgs bosons in the diphoton final state. She is a former convenor of the CMS QCD photons subgroup and a former CMS contact for the H→gamma gamma channel in the LHC Higgs Working Group.
