DOI 10.1007/s100520000492
Test of
N potential models:
Isospin
relations in
d annihilations at rest and the
search for quasinuclear bound states
The CRYSTAL BARREL Collaboration
A. Abele8 -
J. Adomeit7 -
C. Amsler16 -
C.A. Baker5 -
B.M. Barnett3 -
C.J. Batty5 -
M. Benayoun13 -
S. Bischoff8 -
P. Blüm8 -
K. Braune12 -
T. Case1 -
V. Credé3 -
K.M. Crowe1 -
T. Degener2 -
M. Doser6 -
W. Dünnweber12 -
D. Engelhardt8 -
M.A. Faessler12 -
P. Giarritta16 -
R.P. Haddock10 -
F.H. Heinsius1 -
M. Heinzelmann16 -
A. Herbstrith8 -
N.P. Hessey12 -
P. Hidas4 -
C. Holtzhaußen8 -
D. Jamnik12 -
H. Kalinowsky3 -
P. Kammel1 -
J. Kisiel6 -
E. Klempt3 -
H. Koch2 -
M. Kunze2 -
U. Kurilla2 -
M. Lakata1 -
R. Landua6 -
H. Matthäy2 -
C.A. Meyer14 -
F. Meyer-Wildhagen12 -
R. Ouared6 -
K. Peters2 -
B. Pick3 -
M. Ratajczak2 -
C. Regenfus12 -
W. Roethel12 -
S. Spanier16 -
H. Stöck2 -
U. Strohbusch7 -
M. Suffert15 -
J.S. Suh3 -
U. Thoma3 -
M. Tischhäuser8 -
I. Uman12 -
C. Völcker12 -
S. Wallis-Plachner12 -
D. Walther2 -
U. Wiedner6 -
K. Wittmack3
1 University of California, LBNL, Berkeley, CA 94720, USA
2 Universität Bochum, 44780 Bochum, Germany
3 Universität Bonn, 53115 Bonn, Germany
4 Academy of Science, 1525 Budapest, Hungary
5 Rutherford Appleton Laboratory, Chilton, DidcotOX110QX, UK
6 CERN, 1211 Geneva 4, Switzerland
7 Universität Hamburg, 22761 Hamburg, Germany
8 Universität Karlsruhe, 76021 Karlsruhe, Germany
9 University of California, Los Angeles, CA 90024, USA
10 Universität München, 80333 München, Germany
11 LPNHE Paris VI, VII, 75252 Paris, France
12 Carnegie Mellon University, Pittsburgh, PA 15213, USA
13 Centre de Recherches Nucléaires, 67037 Strasbourg, France
14 Universität Zürich, 8057 Zürich, Switzerland
Received: 28 January 2000 / Published online: 23 October 2000 - © Springer-Verlag 2000
Abstract
We have determined branching ratios for antiproton annihilations
at rest on protons or neutrons in liquid deuterium which we compare
to frequencies of isospin-related processes in antiproton-proton
annihilations. Using the annihilation rates into
and
where the annihilation took place on the proton or neutron,
respectively, we discuss the fraction of S-wave and P-wave annihilation
in liquid D2. The frequencies for
and
,
and
and
and the corresponding frequencies
for
p annihilations are used to determine isoscalar
and isovector contributions to the protonium wave function. The isospin
decomposition of the annihilating
p system in the
3S1 or 1S0 state is consistent with both,
pure
p initial wave function and with the predictions
of
N potential models. For the 3P0 state of
the
p atom we find
consistency with a pure
p system at annihilation
while
N potential models predict large
n contributions.
We observe
-
interference in
p
and
annihilation which we compare to
-
interference in e+e- annihilation. The interference
patterns show striking similarities due to similar phase relations;
the interference magnitude depends on the
-
production
ratio.
The similarity of the phase in all 3 data sets demonstrates that
isovector
and isoscalar parts of the protonium (
p atomic) wave
function are relatively real, again in conflict with
N
potential models.
The annihilation rate for
d
K-K0p
confirms the dominance of the isovector contribution to
N
K
annihilations.
No complications due to initial state interactions are required by the
data.
Furthermore, we searched for narrow quasinuclear bound states close to
the
N threshold, also predicted by
N
potential models, but with negative outcome. We conclude that
N potential models are not suited to provide insight
into the dynamics of the annihilation process.
Copyright Società Italiana di Fisica, Springer-Verlag 2000