D meson
The D mesons are the lightest particle containing charm quarks. They are often studied to gain knowledge on the weak interaction. [1] The strange D mesons (Ds) were called the "F mesons" prior to 1986.
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Overview [edit]
The D mesons were discovered in 1976 by the Mark I detector at the Stanford Linear Accelerator Center.[2]
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 violate 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 Ks and πs. [1]
In November 2011, researchers at the LHCb experiment at CERN reported (3.5 sigma significance) that they have observed a direct CP violation in the neutral D meson decay, possibly beyond the Standard Model.[3]
List of D mesons [edit]
| Particle name | Particle symbol |
Antiparticle symbol |
Quark content[4] |
Rest mass (MeV/c2) | IG | JPC | S | C | B' | Mean lifetime (s) | Commonly decays to (>5% of decays) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| D meson[5] | D+ | D− | cd | 1,869.62 ± 0.20 | 1⁄2 | 0− | 0 | +1 | 0 | 1.040 ± 0.007 × 10−12 | See D+ decay modes |
| D meson[6] | D0 | D0 | cu | 1,864.84 ± 0.17 | 1⁄2 | 0− | 0 | +1 | 0 | 4.101 ± 0.015 × 10−13 | See D0 decay modes |
| Strange D meson[7] | D+ s |
D− s |
cs | 1,968.47±0.33 | 0 | 0− | +1 | +1 | 0 | 5.00±0.07×10−13 | See D+ s decay modes |
| D meson[8] | D∗+(2010) | D∗−(2010) | cd | 2,010.27.62 ± 0.17 | 1⁄2 | 1− | 0 | +1 | 0 | 6.9 ± 1.9 × 10−21[a] | D0 + π+ or D+ + π0 |
| D meson[9] | D∗0(2007) | D∗0(2007) | cu | 2,006.97 ± 0.19 | 1⁄2 | 1− | 0 | +1 | 0 | >3.1 × 10−22[a] | D0 + π0 or D0 + γ |
[a] ^ PDG reports the resonance width (Γ). Here the conversion τ = ħ⁄Γ is given instead.
See also [edit]
References [edit]
- ^ a b D Meson
- ^ http://www.kudryavtsev.staff.shef.ac.uk/phy466/charmed-mesons_files/charmed-mesons.ppt
- ^ New Physics at LHC? An Anomaly in CP Violation : Cosmic Variance
- ^ C. Amsler et al.. (2008): Quark Model
- ^ C. Amsler et al.. (2008): Particle listings – D±
- ^ C. Amsler et al.. (2008): Particle listings – D0
- ^ N. Nakamura et al. (2010): Particle listings – D±
s - ^ C. Amsler et al.. (2008): Particle listings – D∗±(2010)
- ^ C. Amsler et al.. (2008): Particle listings – D∗0(2007)
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