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EnglishWe present the first measurement of the angular distribution for the exclusive process p¯p →ψ(2S)→e+e− based on a sample of 6844 events collected by the Fermilab E835 experiment.We find that the angular distribution is well described by the expected functional form dN/d cos θ∗ ∝ 1 + λ cos2 θ∗, where θ∗ is the angle between the antiproton and the electron in the center of mass frame, with λ = 0.67 ± 0.15(stat) ± 0.04(sys). The measured value for λ implies a small but non-zero ψ(2S) helicity 0 formation amplitude in p¯p, comparable to what is observed in J/ψ decays to baryon pairs.
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| Titolo: | Measurement of the angular distribution in anti-p p ---> psi(2S) ---> e+ e- |
| Autori: | |
| Data di pubblicazione: | 2005 |
| Rivista: | |
| Abstract: | We present the first measurement of the angular distribution for the exclusive process p¯p →ψ(2S)→e+e− based on a sample of 6844 events collected by the Fermilab E835 experiment.We find that the angular distribution is well described by the expected functional form dN/d cos θ∗ ∝ 1 + λ cos2 θ∗, where θ∗ is the angle between the antiproton and the electron in the center of mass frame, with λ = 0.67 ± 0.15(stat) ± 0.04(sys). The measured value for λ implies a small but non-zero ψ(2S) helicity 0 formation amplitude in p¯p, comparable to what is observed in J/ψ decays to baryon pairs. |
| Handle: | http://hdl.handle.net/11567/251773 |
| Appare nelle tipologie: | 01.01 - Articolo su rivista |
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http://hdl.handle.net/11567/251773
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