Spin Density Matrix of the $\omega$ in the Reaction $\bar{p} p \, \rightarrow \, \omega \pi^0$ - INSPIRE

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Spin Density Matrix of the $\omega$ in the Reaction $\bar{p} p \, \rightarrow \, \omega \pi^0$

Crystal Barrel

Collaboration

•

C. Amsler
(
- Zurich U.
)

Oct 14, 2014

12 pages

Published in:

Eur.Phys.J.C 75 (2015) 3, 124

Published: Mar 17, 2015

e-Print:

1410.3743 [hep-ex]

DOI:

10.1140/epjc/s10052-015-3341-9

Experiments:

CERN-LEAR

View in:

reference search6 citations

Citations per year

Abstract: (Springer)

The spin density matrix of the

\omega

has been determined for the reaction

{\bar{p}p}\,\rightarrow \,\omega \pi ^0

with unpolarized in-flight data measured by the Crystal Barrel LEAR experiment at CERN. The two main decay modes of the

\omega

into

\pi ^0 \gamma

and

\pi ^+ \pi ^- \pi ^0

have been separately analyzed for various

{\bar{p}}

momenta between 600 and 1940 MeV/c. The results obtained with the usual method by extracting the matrix elements via the

\omega

decay angular distributions and with the more sophisticated method via a full partial wave analysis are in good agreement. A strong spin alignment of the

\omega

is clearly visible in this energy regime and all individual spin density matrix elements exhibit an oscillatory dependence on the production angle. In addition, the largest contributing orbital angular momentum of the

{\bar{p}p~}

system has been identified for the different beam momenta. It increases from

L^{max{\bar{p}p~}}

=

2 at 600 MeV/c to

L^{max{\bar{p}p~}}

=

5 at 1940 MeV/c.

Note:

13 pages, 9 figures, 8 tables

spin: density matrix
spin: alignment
angular distribution
partial wave analysis
angular momentum
Crystal Barrel
CERN LEAR
anti-p p: annihilation
omega(783): hadroproduction
pi0: associated production

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