D meson

The D mesons are the lightest particle that contain charm quarks. They are often studied to gain knowledge on the weak interaction. The strange D mesons (D_s) were called "F mesons" prior to 1986.

Overview

The D mesons were discovered in 1976 by the Mark I detector at the Stanford Linear Accelerator Center.

Since the D mesons are the lightest mesons containing a single charm quark (or antiquark), they must change the charm (anti)quark into an (anti)quark of another type to decay. Such transitions involve a change of the internal charm quantum number, and can take place only via the weak interaction. In D mesons, the charm quark preferentially changes into a strange quark via an exchange of a W particle, therefore the D meson preferentially decays into kaons (Template:Subatomic particle) and pions (Template:Subatomic particle).

List of D mesons

D mesons

Particle name	Particle symbol	Antiparticle symbol	Quark content	Rest mass [MeV/c2]	I	Template:ItcoP	S	C	B′	Mean lifetime [s]	Commonly decays to (>5% of decays)
Charged D meson	Template:Subatomic particle	Template:Subatomic particle	Template:Subatomic particleTemplate:Subatomic particle		Template:Sfrac	0−	0	+1	0
Neutral D meson	Template:Subatomic particle	Template:Subatomic particle	Template:Subatomic particleTemplate:Subatomic particle		Template:Sfrac	0−	0	+1	0
Strange D meson	Template:Subatomic particle	Template:Subatomic particle	Template:Subatomic particleTemplate:Subatomic particle		0	0−	+1	+1	0
Excited charged D meson	Template:Subatomic particle(2010)	Template:Subatomic particle(2010)	Template:Subatomic particleTemplate:Subatomic particle		Template:Sfrac	1−	0	+1	0	‡	Template:Subatomic particle + Template:Subatomic particle or Template:Subatomic particle + Template:Subatomic particle
Excited neutral D meson	Template:Subatomic particle(2007)	Template:Subatomic particle(2007)	Template:Subatomic particleTemplate:Subatomic particle		Template:Sfrac	1−	0	+1	0	> ‡	Template:Subatomic particle + Template:Subatomic particle or Template:Subatomic particle + Template:Subatomic particle

‡ ^ PDG reports the resonance width (Template:Tmath). Here the conversion $\tau =\hslash /\mathrm{\Gamma }$ is given instead.

CP violation

In 2019, an analysis by the LHCb experiment reported the first observation of CP violation in the decays of the neutral Template:Subatomic particle meson, with a significance of over five standard deviations. The results of a subsequent data analysis by the same collaboration was presented in 2022, which announced that they found evidence of direct CP violation in the decay of the Template:Subatomic particle meson into pions.

Template:Subatomic particle–Template:Subatomic particle oscillations

In 2021 it was confirmed with a significance of more than seven standard deviations, that the neutral Template:Subatomic particle meson spontaneously transforms into its own antiparticle and back. This phenomenon is called flavor oscillation and was prior known to exist in the neutral K meson and B meson.

See also

• List of mesons
• List of particles
• Timeline of particle discoveries