# Measurement of the Vcb element in top-quark pair events in CMS

- Institution: CERN
- Speaker: Riccardo Salvatico
- Year: 2026
- Language: English
- Source: [CERN](https://videos.cern.ch/record/3027087)
- Licence: [CERN](https://copyright.web.cern)
- Who can watch: Teens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

Measurements of the CKM matrix element Vcb are presented using proton–proton collision data collected with the CMS detector during the LHC Run 2 and Run 3 periods. The measurements exploit top-quark pair events in which one top quark decays via a W boson to a final state with an electron or a muon and neutrinos, and the other top quark decays via a W boson to a charm quark and a bottom quark. The analyses rely on dedicated CMS jet-flavor tagging algorithms to efficiently and precisely identify jets originating from charm and bottom quarks. Binned maximum-likelihood fits are performed to extract the branching fraction of the decay of a W boson to a charm quark and a bottom quark. This measurement is then used to infer the magnitude of the CKM matrix element Vcb, providing a direct determination of this fundamental parameter from top-quark events.

Coffee will be served at 10h30

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## Lectures

1. [Measurement of the Vcb element in top-quark pair events in CMS](https://invisiblenetwork.ai/learn/cern/3027087/09a22aa9559d), 1 h 11 min (CERN's player)