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Nuclear and Particle Physics

# Search for Higgs boson pair production in the $bb\tau\tau$ final state with the ATLAS detector and investigation of $\pi^0$ reconstruction with alternative $\tau$ jet seeds in hadronic $\tau$ decays.

## by Christina Dimitriadi (Uppsala University)

Europe/Stockholm
668 4093 2777 (Zoom)

### 668 4093 2777

#### Zoom

https://uu-se.zoom.us/j/66840932777
Description

This will be a virtual seminar, and will be hosted in Zoom

Link:
https://uu-se.zoom.us/j/66840932777

Meeting ID: 668 4093 2777

After the discovery of the Higgs boson in 2012, searching for the simultaneous production of two Higgs bosons (HH) in proton-proton collisions would enable us to establish evidence of the Higgs boson self-coupling which is directly linked to the shape of the Higgs potential. Interpretations in Effective Field Theories (EFT) can be beneficial as they provide new physics contributions in a model-independent way. Two different approaches are used, the Higgs EFT and the Standard Model (SM) EFT, and some intermediate results will be presented.

Several HH searches are already being performed in ATLAS with different final states, but no evidence of SM-like HH production is expected until High-Luminosity LHC. The associated production of a single Higgs boson via ZH is a background in HH searches. When considering ZH, the cross-section is larger than for the corresponding SM-like HH channel. A slight modification of the HH search to detect ZH instead of HH with a focus on the $bb\tau\tau$ channel, as a first step towards HH detection, is ongoing and will be also presented.

Furthermore, an overview of my qualification task within the Tau Performance group will be given. The goal is to revisit and improve the neutral pion reconstruction and identification for the standard tau reconstruction, as well as for alternative seed jet and cluster calibrations.