| 词条 | D meson | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 释义 |
| bgcolour = | name = D Meson | image = | caption = | num_types = | composition = {{SubatomicParticle|D+}}: {{SubatomicParticle|Charm quark}}{{SubatomicParticle|Down antiquark}} {{SubatomicParticle|D-}}: {{SubatomicParticle|Down quark}}{{SubatomicParticle|Charm antiquark}} {{SubatomicParticle|D0}}: {{SubatomicParticle|Charm quark}}{{SubatomicParticle|Up antiquark}} {{SubatomicParticle|AntiD0}}: {{SubatomicParticle|Up quark}}{{SubatomicParticle|Charm antiquark}} {{SubatomicParticle|Strange D+}}: {{SubatomicParticle|Charm quark}}{{SubatomicParticle|Strange antiquark}} {{SubatomicParticle|Strange D-}}: {{SubatomicParticle|Strange quark}}{{SubatomicParticle|Charm antiquark}} | statistics = Bosonic | group = Mesons | generation = | interaction = Strong, Weak, Electromagnetic, Gravitational | antiparticle = | theorized = | discovered = | symbol = {{SubatomicParticle|D+}}, {{SubatomicParticle|D-}}, {{SubatomicParticle|D0}}, {{SubatomicParticle|AntiD0}}, {{SubatomicParticle|Strange D+}}, {{SubatomicParticle|Strange D-}} | mass = {{SubatomicParticle|D+-}}: {{val|1869.62|0.20|ul=MeV/c2}} {{SubatomicParticle|D0}}/{{SubatomicParticle|AntiD0}}: {{val|1864.84|0.17|u=MeV/c2}} {{SubatomicParticle|Strange D+-}}: {{val|1968.47|0.33|ul=MeV/c2}} | decay_time = | decay_particle = | electric_charge = {{SubatomicParticle|D+-}},{{SubatomicParticle|Strange D+-}}: ±1 e {{SubatomicParticle|D0}},{{SubatomicParticle|AntiD0}}: 0 e | color_charge = | spin = | num_spin_states = }} 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. OverviewThe 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 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 {{Subatomic particle|link=yes|Kaon}}s and {{Subatomic particle|link=yes|Pion}}s.[1] List of D mesons
[a] {{note|Lifetime}} PDG reports the resonance width (Γ). Here the conversion τ = {{sfrac|ħ|Γ}} is given instead. See also
References 1 : Mesons |
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