PoS - Proceedings of Science
Volume 449 - The European Physical Society Conference on High Energy Physics (EPS-HEP2023) - T10 Searches for New Physics
Search for Heavy Neutral Leptons in $tau$-lepton decays with the $BABAR$ detector.
S. Middleton
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Pre-published on: January 30, 2024
Published on: March 21, 2024
In recent years there have been large improvements in constraining the extended Pontecorvo–Maki–Nakagawa–Sakata (PMNS) matrix element, $|U_{\tau 4}|^{2}$, which describes the mixing between the active $\nu_{\tau}$ and an additional heavy neutral lepton (HNL). We present a model-independent search for a HNL, capable of mixing with $\nu_{\tau}$ using data from \babar. A total of 424 $fb^{-1}$ of electron-positron data is analyzed. Upper limits at the 95 $\%$ confidence level of $2.31 \times 10^{-2} < |U_{\tau 4}|^{2}< 5.04 \times 10^{-6}$ are set, across the mass range $100 < m_{4} < 1300 ~\text{MeV}/c^{2}$. More stringent limits are being placed at higher masses.
DOI: https://doi.org/10.22323/1.449.0471
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