CERN Accelerating science

LHCb Note
Report number	LHCb-CONF-2026-001 ; CERN-LHCb-CONF-2026-001
Title	Measurement of hadronic form-factor parameters with an angular analysis of $B^0 \rightarrow D^{*-} \mu^{+} \nu_{\mu}$ decays
Corporate author(s)	The LHCb Collaboration
Collaboration	LHCb Collaboration
Submitted to	60th Rencontres de Moriond on Electroweak Interactions and Unified Theories, La Thuile, It, 15 - 22 Mar 2026
Submitted by	lhcb.secretariat@cern.ch on 19 Mar 2026
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; LHCb
Free keywords	LHCb ; flavour physics ; B physics,
Abstract	The hadronic form-factor parameters of the $B^{0}\to D^{\ast-} \mu^{+} \nu_\mu$ decay are determined from a differential analysis of the decay rate in dilepton momentum squared, $q^2$, the three helicity angles and the squared invariant mass of the visible system, $m^2_{miss}$. The data sample used corresponds to an integrated luminosity of 3.0 fb$^{-1}$ collected by the LHCb experiment in proton-proton collisions at centre-of-mass energies 7 TeV and 8 TeV. The reconstructed final states are formed by combining $D^{\ast-}$ mesons with $\mu^+$ candidates, where the $D^{\ast-}$ is reconstructed via the $D^{\ast-}\to \kern 0.18em \overline{\kern -0.18em D}{}^0 \pi^-$ and $\kern 0.18em \overline{\kern -0.18em D}{}^0 \to K^+\pi^-$ decay. The data are fitted with three different hadronic form-factor parametrisations, Caprini-Lellouch-Neubert (CLN), Boyd-Grinstein-Lebed (BGL) and Bernlochner-Ligeti-Papucci-Robinson (BLPR). The form-factor parameters associated with three of the four helicity amplitudes are measured. The precision achieved in BGL and BLPR is comparable to lattice QCD determinations, and the results are overall compatible. The CLN results show improved precision for all three measured form factors.

Corresponding record in: Inspire
Email contact(s) : LHCb.secretariat@cern.ch