D meson

The D mesons are the lightest particle that contain charm quarks. They are often studied to gain knowledge on the weak interaction.^[1] The strange D mesons (D_s) were called "F mesons" prior to 1986.^[2]

D meson

Composition	D+ : cd D− : dc D0 : cu D0 : uc D+ s: cs D− s: sc
Statistics	Bosonic
Family	Mesons
Interactions	Strong, weak, electromagnetic, gravitational
Symbol	D+ , D− , D0 , D0 , D+ s, D− s
Antiparticle	D+ : D− D0 : D0 D+ s: D− s
Discovered	SLAC (1976)
Mass	D± : 1869.62±0.20 MeV/c2 D0 ,D0 : 1864.84±0.17 MeV/c2 D± s: 1968.47±0.33 MeV/c2
Mean lifetime	D± : (1.040±0.007)×10−12 s D0 ,D0 : (4.101±0.015)×10−13 s D± s: (5.00±0.07)×10−13 s
Electric charge	D± ,D± s: ±1 e D0 ,D0 : 0 e
Spin	0 ħ
Strangeness	D± ,D0 ,D0 : 0 D± s: ±1
Charm	+1
Isospin	D+ ,D0 : +⁠1/2⁠ D− ,D0 : −⁠1/2⁠ D± s: 0
Parity	−1

Overview

The D mesons were discovered in 1976 by the Mark I detector at the Stanford Linear Accelerator Center.^[3]

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 (K) and pions (π).^[1]

List of D mesons

D mesons

Particle name	Particle symbol	Antiparticle symbol	Quark content[4]	Rest mass [MeV/c2]	I	JP	S	C	B′	Mean lifetime [s]	Commonly decays to (>5% of decays)
Charged D meson[5]	D+	D−	cd	1869.62±0.20	⁠1/2⁠	0−	0	+1	0	(1.040±0.007)×10−12	[6]
Neutral D meson[7]	D0	D0	cu	1864.84±0.17	⁠1/2⁠	0−	0	+1	0	(4.101±0.015)×10−13	[8]
Strange D meson[9]	D+ s	D− s	cs	1968.47±0.33	0	0−	+1	+1	0	(5.00±0.07)×10−13	[10]
Excited charged D meson[11]	D∗+ (2010)	D∗− (2010)	cd	2010.27±0.17	⁠1/2⁠	1−	0	+1	0	(6.9±1.9)×10−21‡	D0 + π+ or D+ + π0
Excited neutral D meson[12]	D∗0 (2007)	D∗0 (2007)	cu	2006.97±0.19	⁠1/2⁠	1−	0	+1	0	> 3.1×10−22‡	D0 + π0 or D0 + γ

‡ ^ PDG reports the resonance width (⁠${\displaystyle \Gamma }$⁠). Here the conversion ${\displaystyle \tau ={\hbar }/{\Gamma }}$ 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 D⁰
meson, with a significance of over five standard deviations.^[13] 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 D⁰
meson into pions.^[14]

D–D oscillations

In 2021 it was confirmed with a significance of more than seven standard deviations, that the neutral D⁰
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.^[15]

See also

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