(1405) photoproduction at cb-elsa · 2014. 4. 3. · bosen 2005 (1405) photoproduction at cb-elsa...
TRANSCRIPT
Vera Kleber
1Bosen, 07.09.2005
PI
Λ ΛΛΛ(1405) Ph
otop
roduc
tion
at CB-ELSA
Vera Kleber
Physikalisch
es Institut
Unive
rsität Bon
n
BOSEN 2005
Vera Kleber
2Bosen, 07.09.2005
PI
Out
line
Motivation
Acc
ess to Λ(1405)
and availab
ledata
Λ(1405) at CB-E
LSA
Outlook
Vera Kleber
3Bosen, 07.09.2005
PI
What‘skno
wn…
Λ(1405)
0(1/2
- )
1406.5±4
.0
50 ±
2
Σ0π0
(33%)
Σ+ π
-(33%)
Σ- π
+(33%)
PDG
Σ0(1385)
I(J
P )1(3/2
+ )
Mass
1383.7 ±
1.0
[MeV]
Width
36 ±
5
[MeV]
Decay
Σ+ π
-( 6%)
Σ- π
+( 6%)
Λπ0
(88%)
S=-1, Σ
0= ud
sS=-1, Λ
0= ud
s
S. Eidelmanet al., Phys. Lett. B 592, 1 (2004)
Vera Kleber
4Bosen, 07.09.2005
PI
Where
doe
sit
come fro
m…
Data:
R.J. Hemingw
ay,
NP B 253 (19
85) 742
Ana
lysis:
R.H. Dalitz, A. Deloff,
JPG
17 (19
91) 289,
M-M
atrix fit
→14
06.5±4.0
50±2
Σ* (16
70)+→
π+Λ(1405)→
π+(πΣ)0
m(π+Σ
)m(K+N)
m(π
− Σ+ )
Vera Kleber
5Bosen, 07.09.2005
PI
Strang
e Particle…
•Dalitzan
d Tua
npredicted(1959) a subth
resh
oldKN resona
ncefrom
K- p sca
ttering
data
→Λ(1405) was disco
vere
da fe
wye
arslater;
only
30 M
eV belowKN thre
shold
•locatedcloseto m
anyth
resh
olds
πΛπ0Σ0 π−Σ+π+Σ−
K- p
K0n
Λ(1405)
Mass
Vera Kleber
6Bosen, 07.09.2005
PI
Lambda S
tate
sin Q
uark
Mod
el
L=1
S=1/2
Vera Kleber
7Bosen, 07.09.2005
PI
Struc
ture
of theΛ ΛΛΛ(1405)
large theoretica
leffort
•qu
arkmod
elstatewithorbital excitation
→massdege
neratedpa
rtne
rwithJ
P =3/2
-
Λ(1520): 115
MeV away
•KN m
olecu
le,dyn
amically
gene
rated
→an
otherJ
P =1/2-Λ near
theΛ(1520)
unob
served
•χ symmetry: dou
ble struc
ture
@ 1405 M
eV
Λ(1405)
Λ(1520)
JP =1/2-
JP =3/2
-
D. Jidoet al.,
Nuc
l. Ph
ys. A
725 (2003) 18
1
a.u.
Λ(?)
Λ(1520)
Vera Kleber
8Bosen, 07.09.2005
PI
Acc
ess
to Λ ΛΛΛ(1405)
aboveKN thre
shold
K- p sca
ttering
data
at KN thresh
old
kaon
ichyd
roge
n
belowKN thre
shold
πΣmassdistribution
Vera Kleber
9Bosen, 07.09.2005
PI
K-p Sca
ttering
J. A. Olle
r, U
.-G. Meissner,
Phys. Lett. B 500 (2001) 263
available
data
aboveKN thresh
old:
→KN sca
ttering
leng
th
→ H
emingw
ay data
canbedescribed
K- p →
K- p
K0n
π+Σ−
π−Σ+
π0Λ
π0Σ0
Vera Kleber
10Bosen, 07.09.2005
PI
Kaon
icHydro
gen
DEAR@DAΦNE
Kao
nicHyd
roge
n
→energysh
iftan
d width
→K- p sca
ttering
leng
th
→Con
sequ
enc
esfo
rΛ(1405) line
shap
e
DEAR
KEK
Γ[eV]
∆E [eV]
Borasoy
et al.,
arXiv:hep-ph
/0505239
M. Cargn
elliet al.,
Int. Mod
. Ph
ys. A20 (2005) 341
Vera Kleber
11Bosen, 07.09.2005
PI
πΣ πΣπΣπΣMass
Distribut
ion: L
EPS
γp→
K+ X
J.K. Ahn, N
ucl. Ph
ys. A 721 (2003) 715
c
LEPS
Vera Kleber
12Bosen, 07.09.2005
PI
πΣ πΣπΣπΣMass
Distribut
ion: L
EPS
γp→
K+ π
+/− Σ
−/+
cuton
m(X
) = m(Σ)
Σ0 (13
85) →
πΣ←
Λ(1405)
66%
12%
π+Σ-
π−Σ+
Λ(1405)
(Σ(1385))
Λ(1520)
J.K. Ahn, Nucl. Phys. A 721 (2003) 715c
Vera Kleber
13Bosen, 07.09.2005
PI
πΣ πΣπΣπΣMass
Distribut
ion: C
rystal Ball
K- p →
Σ0 π
0 π0
↑Λ(1405)
↓Λ(1520)
--ph
asespace
→7γ n
↓ Λγ
↓ π0n
p K-=
581 MeV/c
687 M
eV/c
714
MeV/c
750 M
eV/c
Σ0
Σcu
tan
d bg
subtrac
tion
Vera Kleber
14Bosen, 07.09.2005
PI
TwoΛ ΛΛΛ(1
405) Reso
nanc
es
V.K. Mag
aset al., hep-ph
/0503043
TwoΛ(1405): in expe
rimentssupe
rpositionis
seen
→diffe
rent reac
tion
sca
npick
up th
epo
leswithdiffe
rent streng
th
Vera Kleber
15Bosen, 07.09.2005
PI
Plans
for
Λ(1405) at CB-E
LSA
•massdistribution
invarian
t massof
(Σ0 π
0 ) system
or
missing
massof
K+
•t-distribution
mom
entum
tran
sferto Λ(1405)
ift-ch
anne
ldom
inan
t
→ac
cess
to pK-scattering
amplitud
ebelowth
resh
old
γp→
K+ Λ(1405) → K
+ n5γ
Λγ
Σ0π0
nπ0
Vera Kleber
16Bosen, 07.09.2005
PI
Dom
inant
Pro
duc
tion
Mech
anism
M. Lutz, M
. Soy
eur, arXiv:nuc
l-th
/0407115
Λ(1405)
Vera Kleber
17Bosen, 07.09.2005
PI
Phot
ondete
ctionwith
Cry
stal Barrel
1380 CsJ
(Tl) crystals
angu
lar rang
e12
o –16
8o
solid ang
le0.95 x 4π
δE/E
2.5% @
1 GeV
δθ/θ
∼ ±2o
Vera Kleber
18Bosen, 07.09.2005
PI
Kaon
Ident
ification
kaon
identificationvia itsmass
→expe
rimentally
difficu
lt
equ
vialent:
velocity
and m
omentum
→ve
locity
via time-of-flight(T
OF)
(and
kno
wndistanc
es)
→mom
entum
via mag
neticfield
deflection→
mom
entum
Vera Kleber
19Bosen, 07.09.2005
PI
Cry
talBarrel + M
agn
eticSpe
ctro
mete
r
MOMO:
673 scintillating
fibers
2.5 m
m diameter
3 lay
ers
TOF:
plasticscintalla
torbars
3 x 3 x 0.2 m
3
Crystal
Barre
l
Dipole
0.6 Tm
Track
Detectors
Vera Kleber
20
Bosen, 07.09.2005
PI
TOF versus
Mom
ent
um
→K+ identificationup
to 12
00 M
eV (black
line
)
Simulation: Andre Süle
Vera Kleber
21
Bosen, 07.09.2005
PI
Altern
ative
: CB +
MOMO +
TOF
MOMO:
673 fibers
2.5 m
m diameter
TOF:
plasticscintalla
torbars
3 x 3 x 0.8 m
3
Crystal
Barre
l
Vera Kleber
22
Bosen, 07.09.2005
PI
K+Ident
ification
with
TOF W
all
→K+ identificationup
to 600 M
eV (black
line
)
TOF @
5.3 m
Stefan Höffgen
Vera Kleber
23
Bosen, 07.09.2005
PI
Sum
mary
I
Λ(1405):
well estab
lish
edstateof
unk
nownstructure
3q state↔
KN m
olecu
le↔
twoΛ(1405)
notmuc
hexpe
rimental dataso far
Plan
for
CB-E
LSA: γp→ K
+ Λ(1405) → K
+ n5γ
•5γwell suitedfo
rCB
•K+ (and
n) ID withTOF / M
agn. Spe
ctr.
Vera Kleber
24
Bosen, 07.09.2005
PI
Sum
mary
II
Bene
fitof
this
measurement:
clean
chan
nel(no co
ntributionfrom
Σ(1385))
t-distribution
ift-ch
anne
ldom
inates
→ac
cess
to K
- p sca
ttering
amplitud
ebelowth
resh
old
onemorech
anne
lto test m
assdistributions