Observation of a J(PC)=1-+ exotic resonance in diffractive dissociation of 190   GeV/c π- into π- π- π+.
The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the π- π- π+ final state using a 190  GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420,000 events taken at values of the squared 4-momentum transfer t' between 0.1 and 1  GeV2/c2. The well-known resonances a1(1260), a2(1320), and π2(1670) are clearly observed. In addition, the data show a significant natural-parity exchange production of a resonance with spin-exotic quantum numbers J(PC)=1-+ at 1.66  GeV/c2 decaying to ρπ. The resonant nature of this wave is evident from the mass-dependent phase differences to the J(PC)=2-+ and 1++ waves. From a mass-dependent fit a resonance mass of (1660±10(-64)(+0))  MeV/c2 and a width of (269±21(-64)(+42))  MeV/c2 are deduced, with an intensity of (1.7±0.2)% of the total intensity.
Alekseev
M G
MG
Torino Section of INFN, 10125 Turin, Italy.
Alexakhin
V Yu
VY
Alexandrov
Yu
Y
Alexeev
G D
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Austregesilo
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Badełek
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Balestra
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Ball
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Barth
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Baum
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Bedfer
Y
Y
Bernhard
J
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Bertini
R
R
Bettinelli
M
M
Birsa
R
R
Bisplinghoff
J
J
Bordalo
P
P
Bradamante
F
F
Bravar
A
A
Bressan
A
A
Brona
G
G
Burtin
E
E
Bussa
M P
MP
Chapiro
A
A
Chiosso
M
M
Chung
S U
SU
Cicuttin
A
A
Colantoni
M
M
Crespo
M L
ML
Dalla Torre
S
S
Dafni
T
T
Das
S
S
Dasgupta
S S
SS
Denisov
O Yu
OY
Dhara
L
L
Diaz
V
V
Dinkelbach
A M
AM
Donskov
S V
SV
Doshita
N
N
Duic
V
V
Dünnweber
W
W
Efremov
A
A
El Alaoui
A
A
Eversheim
P D
PD
Eyrich
W
W
Faessler
M
M
Ferrero
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A
Finger
M
M
Finger
M
M
Fischer
H
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Franco
C
C
Friedrich
J M
JM
Garfagnini
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R
Gautheron
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Gavrichtchouk
O P
OP
Gazda
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Gerassimov
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Geyer
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Giorgi
M
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Gobbo
B
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Goertz
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Grabmüller
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Grajek
O A
OA
Grasso
A
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Grube
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B
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von Harrach
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Heinsius
F H
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Höppner
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d'Hose
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Ilgner
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Ivanshin
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Iwata
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Jahn
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Jasinski
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Jegou
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Joosten
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Kabuss
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Kang
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Ketzer
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Khokhlov
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Kisselev
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Klimaszewski
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Koivuniemi
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Kondo
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Konorov
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V F
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Korzenev
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A M
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Kouznetsov
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Kowalik
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Krämer
M
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Kral
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Kroumchtein
Z V
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Kuhn
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Kunne
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Kurek
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Lauser
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Le Goff
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Lednev
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Lehmann
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Lichtenstadt
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Liska
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Maggiora
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Magnon
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Marchand
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Martin
A
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Massmann
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Matsuda
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Maximov
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Meyer
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Michigami
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S
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Neyret
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Nikolaenko
V I
VI
Olshevsky
A G
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Padee
A
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Panknin
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Panzieri
D
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Parsamyan
B
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Paul
S
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Pawlukiewicz-Kaminska
B
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Perevalova
E
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Pesaro
G
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Peshekhonov
D V
DV
Piragino
G
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Platchkov
S
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Pochodzalla
J
J
Polak
J
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Polyakov
V A
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Pontecorvo
G
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Quintans
C
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Rajotte
J-F
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Ramos
S
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Rapatsky
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Reicherz
G
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Reggiani
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Richter
A
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Robinet
F
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Rocco
E
E
Rondio
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Ryabchikov
D I
DI
Samoylenko
V D
VD
Sandacz
A
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Santos
H
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Sapozhnikov
M G
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Sarkar
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Savin
I A
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Sbrizzai
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Schiavon
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Schill
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Schlüter
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Schmitt
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Schopferer
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Srnka
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Windmolders
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