charged Higgs boson

charged Higgs boson The charged Higgs boson is a hypothetical electrically charged scalar particle predicted in extensions of the Standard Model such as the Two-Higgs-doublet model and Minimal Supersymmetric Standard Model, and it represents an electrically charged counterpart to the neutral Higgs boson discovered at CERN's Large Hadron Collider by the ATLAS experiment and CMS experiment. Searches for H^± have been pursued at facilities including the Large Electron–Positron Collider, Tevatron, LEP, LHCb experiment, CMS experiment, and ATLAS experiment, and constraints inform model-building in frameworks like supersymmetry, Grand Unified Theory, and flavor physics studies.

Overview

The charged Higgs boson appears in models that extend the Higgs mechanism implemented in the Standard Model and arises naturally in the Two-Higgs-doublet model variants such as Type I, Type II, and aligned two-Higgs-doublet constructions considered alongside frameworks like the Minimal Supersymmetric Standard Model and Next-to-Minimal Supersymmetric Standard Model. Phenomenologically, H^± carries electric charge ±1 and is a spin-0 state whose mass, couplings, and mixing angles are constrained by data from experiments at CERN, the Fermilab Tevatron, the KEK Belle experiment, and flavor observables measured at BaBar and LHCb. Theoretical inputs from groups at institutions such as DESY, SLAC, IPPP, and IHEP inform predictions used by collaborations like ATLAS experiment and CMS experiment to design targeted searches.

Theoretical Framework

Charged Higgs bosons are generic in multi-doublet scalar sectors like the Two-Higgs-doublet model, where two SU(2)_L doublets produce five physical Higgs states: two CP-even, one CP-odd, and two charged states; this structure is central to constructions such as the Minimal Supersymmetric Standard Model and various left–right symmetric model implementations. Model parameters include tanβ (the ratio of vacuum expectation values), mixing angles, and soft-breaking terms often motivated by supersymmetry breaking scenarios studied by collaborations at CERN, Fermilab, KEK, and theoretical groups at Princeton University and University of Cambridge. Constraints arise from precision electroweak fits influenced by measurements at LEP, SLD, and Tevatron, and from flavor observables such as rare decays analyzed by Belle experiment, BaBar, and LHCb experiment, which together restrict parameter spaces in global fits performed by groups at IPPP, CERN Theory Division, and national laboratories.

Production and Decay Modes

At hadron colliders like the Large Hadron Collider and the former Tevatron, charged Higgs bosons can be produced in top-quark related processes (e.g., t → H^+ b) and in associated production with heavy quarks or gauge bosons; production mechanisms are modeled using generators developed by teams at CERN, SLAC, and Fermilab and validated against data from ATLAS experiment and CMS experiment. Decay modes depend on the mass regime: for light H^± (m < m_top) decays to τν and cs are prominent, while for heavy H^± (m > m_top) decays to tb, W^± plus neutral Higgses, or cascade decays appearing in supersymmetry scenarios dominate; branching ratios are computed in frameworks employed by the Les Houches Accord community and by groups at DESY and Institut de Physique Théorique. Experimental strategies exploit signatures in detectors built by collaborations such as ATLAS experiment, CMS experiment, LHCb experiment, and historical searches at LEP and the Tevatron.

Experimental Searches and Constraints

Searches by the ATLAS experiment and CMS experiment at the Large Hadron Collider have set limits on charged Higgs production cross sections and branching fractions across mass ranges, complementing bounds from LEP experiments and Tevatron analyses by CDF and DØ. Flavor physics constraints from measurements by Belle experiment, BaBar, and LHCb experiment—including observables in B → X_s γ, B → τν, and semileptonic B decays—place stringent indirect limits that shape exclusions presented in combined fits from collaborations at CERN, IPPP, DESY, and INFN. Dedicated searches target τν, tb, and multi-lepton final states using techniques developed by analysis groups at University of Oxford, MIT, University of California, Berkeley, and University of Tokyo, and results are incorporated into global likelihood scans by theory teams at KIT, CERN Theory Division, and Perimeter Institute.

Implications for Beyond Standard Model Physics

The existence or exclusion of charged Higgs bosons has direct implications for models such as the Minimal Supersymmetric Standard Model, Two-Higgs-doublet model, left–right symmetric model, composite Higgs model, and variants of Grand Unified Theory constructions; constraints feed into model selection and parameter tuning by researchers at CERN, DESY, SLAC, and university groups worldwide. Observation of H^± would provide evidence for an extended scalar sector, influence interpretations of electroweak symmetry breaking debated in seminars at ICHEP and Moriond Conference, and impact flavor and CP-violation studies pursued by collaborations at LHCb experiment, Belle II, and theoretical programs at Perimeter Institute and Institute for Advanced Study. Continued searches at future facilities such as the High-Luminosity Large Hadron Collider, proposed machines like the International Linear Collider and Future Circular Collider, and planned experiments at KEK will refine sensitivity and either discover charged Higgs states or push exclusion limits that guide theory work at institutions including CERN Theory Division, IPPP, and national laboratories.

Category:Hypothetical elementary particles