CERN Accelerating science

Semileptonic B Decays


  • determine the best values of the inclusive and exclusive semileptonic B decay branching ratios from the combined data.
  • determining the best possible values of F(1)|Vcb| and of the inclusive semileptonic B decay rate.
  • use a consistent approach for the moments.
    • using consistent approaches in all the experiments based on the latest theoretical etc developments,
    • checking consistency of results between the expts,
    • evaluating the systematics common to all the expts,
    • comparing the results of the different methods properly taking account of any common experimental systematics
  • trying if possible to understand their theoretical errors and how to control and minimise them in discussion with theorists.



Previous averages can be found on the webpages of the LEP VCB working group and the LEP VUB working group.

Date Update Information Remarks
Moriond 2024   Includes new preliminary simultaneous measurement of R(D) and R(D*) with muonic decay of the tau from LHCb presented at Moriond 2024 on 27 March 2024
Summer 2023  

Includes new preliminary measurement of R(D*) with leptonic tau and hadronic tagging from Belle II presented at the Lepton Photon Conference 2023.

The plot for combined R(D)-R(D*) with contours at 68% CL is available (the old with Δχ2=1 contours is still linked)

Winter 2023   Includes new preliminary measurement of R(D*) with hadronic tau decay from LHCb (Presented at the CERN LHC seminar 21/Mar/2023). The new result is an average between published R(D*) with Run1 data and additional 2/fb from Run2 data.
End of 2022   Includes preliminary combined measurement of R(D)-R(D*) with tau->mu from LHCb (Presented at the CERN LHC seminar 18/Oct/2022). Final average updated on March 21st 2023 to fix a bug in the LHCb input file.

Spring 2021

common.param 2021 Averages
Spring 2019 common.param PDG 2019 / Spring 2019 Averages
Summer 2018   LHCb measurement of R(D*) with hadronic τ→3π(π0)ν decay mode, has been updated to the published result. The SM predictions for R(D) and R(D*) have been updated to the recent calculations.
FPCP 2017   Includes the R(D*) measurement from LHCb presented at FPCP, where the τ is reconstructed into hadronic τ→3πν decay mode.
Moriond EW 2017   Update for R(D*) with hadronic τ decay by Belle presented at ICHEP2016 (arXiv:1612.00529).
Summer 2016 update   common.param Summer 2016 averages
Winter 2016   Update for R(D(*))=BF(B→D(*)τντ)/BF(B→D(*) l νl) with a Belle preliminary result presented at Moriond EW.
EPS-HEP 2015   First average for R(D(*))=BF(B→D(*)τντ)/BF(B→D(*) l νl). All the other averages have not been updated.
Summer 2014/PDG 2014 update   common.param Summer 2014 averages, also used for the PDG2014
PDG 2013 update update   common.param Results used for the PDG2013 update and PDG2014 Vcb and Vub review
End Of Year 2011/PDG 2012 update   common.param End Of Year 2011 averages. Results also used for the PDG2012
End Of Year 2009/Winter 2010 update   common.param End Of Year 2009 averages.
PDG 2010 update   common.param Many new averages. Results used for the PDG 2010
FPCP 2009 update   common.param FPCP09 averages.
ICHEP 2008 update   common.param ICHEP08 averages.
End Of Year 2007 update   common.param Updates with preliminary results which do not appear in the PDG08 averages. Results are included in [arXiv:0808.1297].
PDG 2008 update   common.param Many new averages. Results used for the PDG2008
LP 2007 update   common.param Summer 2007 results
PDG 2007 update   common.param Results used for the PDG07
Summer 2006 update   common.param Preliminary
ICHEP 2006 update   common.param Preliminary
Winter 2006 update   common.param Preliminary
PDG 2006 update   common.param Preliminary 
EPS 2005 update   common.param Preliminary 
Lepton-Photon 2005 update   common.param Preliminary 
Winter 2005 update   common.param Preliminary 
PDG 2005 update   common.param Changes to some BF for PDG web update
Summer 2004 (Beijing) update   common.param Many new Vub results, the averages are still preliminary! 
Winter 2004 update   common.param No new results, but an inclusive Vub average. First version of written documentation 
PDG 2004 update   common.param No substantial change with respect to PDG 2003 
LP 2003 update   common.param New BABAR result on |Vcb| from B0->D*lnu
EPS 2003 update   common.param New CLEO inclusive semileptonic branching ratio  
PDG 2003 update   common.param Changes to D*lnu by exclusion/supercession of old ARGUS and CLEO analyses  
Winter 2003 update   common.param Updates from BABAR for D*lnu and BABAR/Belle for |Vub|  
Summer 2002 update   common.param Migration to new presentation. Information identical to old webpages


Members of the Sub-Group

Experiment Contact Persons
BABAR Marcello Rotondo (also LHCb)

Jochen Dingfelder
Christoph Schwanda
Phillip Urquijo


Concezio Bozzi (also BaBar)

Lucia Grillo

Further contributors:
Marina Artuso (CLEO), Elisabetta Barberio (BELLE), Oliver Buchmueller (CMS, former BABAR), Henning Flaecher (ATLAS, former BABAR), Bob Kowalewski (BABAR, former convener), Heiko Lacker (BABAR, former member), Vera Luth (BABAR, former member), Matthew Jones (CDF, former member), Art Snyder (BABAR)

We gratefully acknowledge the advice of:
Antonio Limosani (BELLE, former convener), and David Lopez Pegna (BABAR, former convener).

You can send a mail to the entire group with

This page is maintained by Marcello Rotondo