Physics and Astronomy » High Energy Physics »


30 Sep 2022


The Higgs boson was discovered via its decays to bosons by the ATLAS and CMS collaborations in 2012 and has since been observed in decays to tau leptons. Until very recently, it had however not directly been observed coupling to the quark sector, which includes its largest decay to a pair of b-quarks. To fully probe the new particle it is vital to directly observe its coupling to quarks and to precisely measure its decay to b-quarks. UCL pioneered this decay channel and has since played a leading role in observing the Higgs decaying to a pair of b-quarks. Despite the large branching ratio, this is a very challenging channel, which requires great understanding of the complex and large background processes. However, studying this channel is vital to fully understand the nature of the Higgs boson disocvered at the LHC and to unravel the mysteries surrounding the Higgs sector.

Key Academics

Jon Butterworth
Tim Scanlon

Leadership Positions

Tim Scanlon - ATLAS H->bb Subgroup Covener 2016-2017
Tim Scanlon - ATLAS Editor for H->bb and VH Observation Paper

Key References

  • J. Butterworth, A. Davidson, M. Rubin, G. Salam, Jet substructure as a new Higgs search channel at the LHC
    Phys.Rev.Lett. 100 (2008) 242001

  • ATLAS Collaboration, Search for the bb decay of the Standard Model Higgs boson in associated (W/Z)H production with the ATLAS detector
    JHEP 1501 (2015) 069

  • J. Butterworth, I. Ochoa, T. Scanlon, Boosted Higgs→bb in vector-boson associated production at 14 TeV
    Eur.Phys.J. C75 (2015) no.8, 366

  • ATLAS Collaboration, Evidence for the H→bb decay with the ATLAS detector
    JHEP 12 (2017) 024

  • ATLAS Collaboration, Observation of H→bb decays and VH production with the ATLAS detector
    Phys. Lett. B 786 (2018) 59

    The di-b-jet mass peak from the ATLAS VH, H->bb analysis after all backgrounds except for diboson VZ, Z->bb have been substracted. The H->bb signal mass peak (red solid histogram) can be seen on the shoulder of the diboson mass peak (grey solid histogram).