Measurement of the angular distribution in $\bar p p\to ψ(2S)\to e^+e^-$
| dc.creator | Fermilab E835 Collaboration | |
| dc.creator | Ambrogiani, M. | |
| dc.date | 2004-12-01 | |
| dc.date | 2005-01-28 | |
| dc.date.accessioned | 2026-07-07T11:43:13Z | |
| dc.date.available | 2026-07-07T11:43:13Z | |
| dc.description | We present the first measurement of the angular distribution for the exclusive process $\bar p p \to ψ(2S)\to e^+e^-$ 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 $\frac{dN}{d\cosθ^{*}}$ $\propto$ 1 + $λ\cos^{2}θ^{*}$, where $θ^{*}$ is the angle between the antiproton and the electron in the center of mass frame, with $λ$ = 0.67 $\pm$ 0.15 (stat.) $\pm$ 0.04 (sys.) The measured value for $λ$ implies a small but non zero $ψ(2S)$ helicity 0 formation amplitude in $\bar p p$, comparable to what is observed in $J/ψ$ decays to baryon pairs. | |
| dc.description | Accepted by Phys. Lett. B | |
| dc.identifier | https://arxiv.org/abs/hep-ex/0412007 | |
| dc.identifier | http://arxiv.org/abs/hep-ex/0412007 | |
| dc.identifier | Phys.Lett.B610:177-182,2005 | |
| dc.identifier | doi:10.1016/j.physletb.2005.01.093 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/201161 | |
| dc.subject | High Energy Physics - Experiment | |
| dc.title | Measurement of the angular distribution in $\bar p p\to ψ(2S)\to e^+e^-$ | |
| dc.type | text |