Novel strategy targeting HH and HHH production at High Level Trigger in Run 3

For 2023, by exploiting the recent improvements in heavy flavour tagging, a new trigger strategy targeting HH and HHH production is deployed at the High Level Trigger (HLT) of the CMS experiment. The new trigger applies a selection criterion based on the total transverse momentum of jets HT $> 280$ GeV, the presence of at least 4 central jets with $p_{T} > 30$ GeV and the average ParticleNet b-tagging score of the two small-radius jets with the highest b-tag scores above 0.55. In addition, in 2023, the Level 1 trigger requirement on HT is lowered from 360 GeV to 280 GeV compared to 2022 and 2018. By exploiting the Data Parking strategy, which allows a higher rate and acceptance at the cost of delayed reconstruction, this new HLT trigger records events at 180 Hz at an instantaneous luminosity of $2\times10^{34}$ cm$^{-2}$ s$^{-1}$. The following studies show the performance of this new trigger for $HH\rightarrow 4b$, $HH\rightarrow2b2\tau$, $HHH\rightarrow6b$ and $HHH\rightarrow4b2\tau$ production and corresponding decay modes.