Publication

Precision Measurement of the Branching Fraction of D+ →μ+νμ

2025

Abstract

Using 20.3 fb-1 of e+e- collision data collected at a center-of-mass energy of Ec.m.=3.773 GeV with the BESIII detector operating at the BEPCII collider, we determine the branching fraction of the leptonic decay D+→μ+νμ to be (4.034±0.080stat±0.040syst)×10-4. Interpreting our measurement with knowledge of the Fermi coupling constant GF, the masses of the D+ and μ+ as well as the lifetime of the D+, we determine fD+|Vcd|=(48.02±0.48stat±0.24syst±0.12input±0.15EM) MeV after taking into account necessary radiative corrections. This result is a factor of 2.3 more precise than the previous best measurement. Using the value of the magnitude of the c→d Cabibbo-Kobayashi-Maskawa matrix element |Vcd| given by the global standard model fit, we obtain the D+ decay constant fD+=(213.5±2.1stat±1.1syst±0.8input±0.7EM) MeV. Alternatively, using the value of fD+ from a precise lattice quantum chromodynamics calculation, we extract |Vcd|=0.2265±0.0023stat±0.0011syst±0.0009input±0.0007EM.

Official source

https://infoscience.epfl.ch/entities/publication/6c65bb24-7cf9-4099-ab15-a3e6b9d23a59

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2025

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/6c65bb24-7cf9-4099-ab15-a3e6b9d23a59

About this result

Related concepts (27)

Quantum chromodynamics

In theoretical physics, quantum chromodynamics (QCD) is the theory of the strong interaction between quarks mediated by gluons. Quarks are fundamental particles that make up composite hadrons such as the proton, neutron and pion. QCD is a type of quantum field theory called a non-abelian gauge theory, with symmetry group SU(3). The QCD analog of electric charge is a property called color. Gluons are the force carriers of the theory, just as photons are for the electromagnetic force in quantum electrodynamics.

Lepton

In particle physics, a lepton is an elementary particle of half-integer spin (spin ) that does not undergo strong interactions. Two main classes of leptons exist: charged leptons (also known as the electron-like leptons or muons), and neutral leptons (better known as neutrinos). Charged leptons can combine with other particles to form various composite particles such as atoms and positronium, while neutrinos rarely interact with anything, and are consequently rarely observed. The best known of all leptons is the electron.

Mathematical formulation of the Standard Model

This article describes the mathematics of the Standard Model of particle physics, a gauge quantum field theory containing the internal symmetries of the unitary product group SU(3) × SU(2) × U(1). The theory is commonly viewed as describing the fundamental set of particles – the leptons, quarks, gauge bosons and the Higgs boson. The Standard Model is renormalizable and mathematically self-consistent, however despite having huge and continued successes in providing experimental predictions it does leave some unexplained phenomena.

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