Physics Letters B 762 (2016) 102–106
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
Coherent pion production in proton–deuteron collisions
S. Dymov
a,b,∗
, V. Shmakova
b
, D. Mchedlishvili
a,c
, T. Azaryan
b
, S. Barsov
d
, A. Dzyuba
d
,
R. Engels
a
, R. Gebel
a
, P. Goslawski
e
, B. Gou
f
, K. Grigoryev
d,g
, M. Hartmann
a
,
A. Kacharava
a
, V. Komarov
b
, A. Khoukaz
e
, P. Kulessa
h
, A. Kulikov
b
, V. Kurbatov
b
,
N. Lomidze
c
, B. Lorentz
a
, G. Macharashvili
c
, S. Merzliakov
a
, M. Mielke
e
,
S. Mikirtytchiants
a,d
, M. Nioradze
c
, H. Ohm
a
, M. Papenbrock
e
, D. Prasuhn
a
,
F. Rathmann
a
, V. Serdyuk
a
, H. Seyfarth
a
, H. Ströher
a
, M. Tabidze
c
, S. Trusov
a,i
,
D. Tsirkov
b
, Yu. Uzikov
b,j,k
, Yu. Valdau
d,l
, C. Wilkin
m
, P. Wüstner
n
a
Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich, Germany
b
Laboratory of Nuclear Problems, Joint Institute for Nuclear Research, RU-141980 Dubna, Russia
c
High Energy Physics Institute, Tbilisi State University, GE-0186 Tbilisi, Georgia
d
St. Petersburg Nuclear Physics Institute, RU-188350 Gatchina, Russia
e
Institut für Kernphysik, Universität Münster, D-48149 Münster, Germany
f
Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
g
Physikalisches Institut (IA), RWTH Aachen, 52056 Aachen, Germany
h
Institute of Nuclear Physics, PL-31342 Cracow, Poland
i
Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, RU-119991 Moscow, Russia
j
Department of Physics, Lomonosov Moscow State University, RU-119991 Moscow, Russia
k
Dubna State University, RU-141980 Dubna, Russia
l
Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, Bonn, Germany
m
Physics and Astronomy Department, UCL, Gower Street, London WC1E 6BT, United Kingdom
n
Zentralinstitut für Elektronik, Forschungszentrum Jülich, D-52425 Jülich, Germany
a r t i c l e i n f o a b s t r a c t
Article history:
Received
12 August 2016
Received
in revised form 2 September 2016
Accepted
10 September 2016
Available
online 14 September 2016
Editor:
V. Metag
Keywords:
Pion
production
Analysing
powers
Spin
correlations
Values of the proton analysing power in the pd →
3
He π
0
/
3
H π
+
reactions at 350–360 MeV per nucleon
were obtained by using a polarised proton beam incident on a deuterium cluster-jet target and with a
polarised deuteron beam incident on a target cell filled with polarised hydrogen. These results have a
much larger angular coverage than existing data. First measurements are also presented of the deuteron
vector analysing power and the deuteron–proton spin correlations. Data were also obtained on the
deuteron–proton spin correlation and proton analysing power at small angles at 600 MeV per nucleon,
though the angular coverage at this energy was much more restricted even when using a deuteron beam.
By combining the extrapolated values of the spin correlations to the forward or backward directions with
published measurements of the deuteron tensor analysing powers, the relative phases between the two
non-vanishing amplitudes were evaluated.
© 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
The simplest coherent pion production reaction, where all the
final nucleons are bound in a nucleus, is pp → dπ
+
and the asso-
ciated
literature is very extensive and the database enormous [1].
However, because of the identical nature of the two initial protons,
odd and even pion waves do not interfere in the differential cross
*
Corresponding author at: Institut für Kernphysik, Forschungszentrum Jülich,
D-52425 Jülich, Germany.
E-mail
address: s.dymov@fz-juelich.de (S. Dymov).
section which, as a consequence, is symmetric around 90
◦
in the
centre-of-mass (c.m.) frame. The first more general coherent pion
production reaction is pd →
3
He π
0
, where striking effects arising
from the interference between s and p partial waves are observed
in the differential cross section even very near threshold [2,3].
Since there is only one isospin amplitude, the cross section for
pd →
3
H π
+
should be twice that for pd →
3
He π
0
but all the
polarisation observables should be identical for the two reactions.
On the other hand, the
1
2
+
1
+
→
1
2
+
0
−
spin structure leads to six
http://dx.doi.org/10.1016/j.physletb.2016.09.015
0370-2693/
© 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.
资源评论
