Research project Higgs Particles, Baryogenesis and Gravitational Waves with ATLAS data

This project aims at developing a new class of experimental probes for new Higgs-like spin-0 particles with the ATLAS experiment at LHC, and to interpret the experimental results in complete models that predict primordial Gravitational Waves (GW).

The new particles are predicted by Beyond the Standard Model theories that can explain the baryon-antibaryon asymmetry of the universe (BAU), one of the holy grails of modern fundamental physics. We focus on the unexplored asymmetric Higgs decay X->SH , where X and S denote two BSM spin-0 Higgs-like neutral particles while H denotes the already experimentally known Higgs boson. The existence of several new Higgs-like spin-0 particles is perfectly compatible with state-of-the-art Higgs precision physics and leads to dramatic experimental signatures. Asymmetric Higgs decays are present in most BSM Higgs extensions.

The goals of this project are:

  1. a) Utilize the ATLAS Run-2 and Run-3 data to search for additional spin-0 Higgs particles in the very characteristic and low background final state with two b-quarks and two photons.
  2. Interpretation of the experimental results in the framework of complete models and synergy with primordial Gravitational Wave (GW) searches. Populations of models that can be probed both with HL-LHC projected data and future space-based GW telescopes such as LISA will be identified, and models relevant to primordial GW excluded by our full Run-3 will be identified.

Department of Physics

Fysikum physicists among winners of prestigious Breakthrough Prize in Fundamental Physics

Scientists from Stockholm University are among the worldwide researchers honored with the 2025 Breakthrough Prize in Fundamental Physics, awarded to the ATLAS Collaboration at CERN's Large Hadron Collider (LHC) alongside its sister experiments ALICE, CMS and LHCb. The prize was founded in 2012 by Yuri Milner to recognize those individuals who have made profound contributions to human knowledge.

Department of Physics

Sara Strandberg on Wallenberg Scholar and the Higgs particle

The Wallenberg Scholars program supports and stimulates some of the most successful senior researchers at Swedish universities. The grant is for five years with the possibility of a five-year extension. There are currently 88 active Wallenberg Scholars and Emil Bergholtz was recently appointed. Sara Strandberg received a five-year extension. On April 12, Sara participated in the Swedish Radio program Vetenskapsradion on the topic of the Higgs particle.

Department of Physics

A scientific train journey to CERN with Sara Strandberg

On 15 April, the train departs from Stockholm to Geneva and cicerones are particle physicist Professor Sara Strandberg from Fysikum and science journalist Anna Davour from Forskning & Framsteg. Participants will learn more about the smallest components of our matter with quarks, leptons and other elementary particles. CERN is the world's largest particle physics laboratory and home to the Large Hadron Collider - the world's largest particle accelerator. The particle physics group at SU conducts research on the role of the Higgs particle in various extensions of the current Standard Model. We are also a driving force in projects concerning supersymmetric extensions of the Standard Model that can, among other things, solve the Higgs fine-tuning problem and explain dark matter. "In a large project funded by the Knut and Alice Wallenberg Foundation, we are searching for the supersymmetric partner of the top quark using data from the ATLAS experiment at CERN. We have pushed our limits on the masses of supersymmetric particles, and developed new search strategies and techniques that are expected to be of lasting benefit to the field," Strandberg explains. The project ended at the end of the year, but the scientific collaborations continue. Thanks to a new grant from the Swedish Research Council to the Swedish LHC consortium, Sweden's participation in the ALICE and ATLAS experiments at the LHC is funded for another 6 years. This means that it will be possible to continue experimental research at the LHC. The consortium consists of one representative per university from Stockholm University, KTH, Lund University and Uppsala University. In total, about 150 people in Sweden are involved in research at CERN, of which about 100 are involved in the LHC experiments. In addition to the city tour and the visit to CERN, participants will also visit a vineyard where local wines are produced. "There may also be a science quiz during the train journey," says Sara Strandberg.   More information Train trip to CERN (in Swedish) CERN (Conseil Européen pour la Recherche Nucléaire) LHC (Large Hadron Collider) - The worlds largest particle accelerator ALICE experiment ATLAS experiment Higgs Boson - Higgs boson Professor Sara Strandberg, Fysikum World's largest particle accelerator restarts An Open Lecture with Sara Strandberg talking about the ATLAS experiment

No events available.