# Measurement of the semitauonic decay B0 -> D*- tau+ nu at LHCb

- Institution: CERN
- Department: LHC Seminar
- Speaker: Brian Hamilton
- Year: 2015
- Language: English
- Source: [CERN](https://videos.cern.ch/record/3015345)
- Licence: [CERN](http://copyright.web.cern.ch)
- Who can watch: Teens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

Semileptonic b decays to tau leptons provide a powerful probe for violations of charged lepton universality due to physics beyond the standard model. In particular, new particles with Higgs-like enhanced couplings to the third generation fermions may induce large deviations from the well-understood standard model expectations. The decay rates for these processes remain poorly measured compared to the corresponding processes involving the light leptons, and tantalizing but inconclusive hints of a deviation from the Standard Model have been reported. A new measurement of the ratio of branching fractions R(D*)=B(B0 -> D*- tau+ nu)/B(B0 -> D*- mu+ nu) using the LHCb Run 1 dataset is presented, where the tau is selected in the tau+ -> mu+ nu anti-nu decay mode. This is the first measurement of a b -> X tau nu process at a hadron collider. .

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## Lectures

1. [Measurement of the semitauonic decay B0 -> D*- tau+ nu at LHCb](https://invisiblenetwork.ai/learn/cern/3015345/d2664beab37c), 1 h 13 min (CERN's player)