Speaker
Description
A search for pairs of light neutral pseudoscalar bosons ($A$) resulting from the decay of a Higgs boson is performed. The search is conducted using LHC proton-proton collision data at $\sqrt{s}=13~\mathrm{TeV}$, collected with the CMS detector in 2016--2018 and corresponding to an integrated luminosity of $138~\mathrm{fb}^{-1}$. The $A$ boson decays into a highly collimated electron-positron pair. A novel multivariate algorithm using tracks and calorimeter information is developed to identify these distinctive signatures, and events are selected with two such merged electron-positron pairs. No significant excess above the standard model background predictions is observed. Upper limits on the branching fraction for $H\to AA\to 4e$ are set at 95% confidence level, for masses between $10$ and $100~\mathrm{MeV}$ and proper decay lengths below $100~\mu\mathrm{m}$, reaching branching fraction sensitivities as low as $10^{-5}$. This is the first search for Higgs boson decays to four electrons via light pseudoscalars at the LHC. It significantly improves the experimental sensitivity to axion-like particles with masses below $100~\mathrm{MeV}$.
| 请选择分会 | TeV物理和超出标准模型新物理 |
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