1. No category

GSI と FAIR における
(p,d)反応を用いた
η′中間子原子核分光実験
Hiroyuki Fujioka (Kyoto Univ.)
on behalf of η-PRiME collaboration
η-PRiME Collaboration
K.-T. Brinkmann, S. Friedrich, H. Fujioka(*), H. Geissel, R.S. Hayano,
Y. Higashi, S. Hirenzaki, Y. Igarashi, N. Ikeno, K. Itahashi(*),
M. Iwasaki, D. Jido, V. Metag, T. Nagae, H. Nagahiro, M. Nanova,
T. Nishi, H. Outa, K. Suzuki, T. Suzuki, Y.K. Tanaka, Y.N. Watanabe,
H. Weick, H. Yamakami
(*) spokesperson
!
University Gießen, Kyoto University, GSI, University of Tokyo,
Nara Women's University, KEK, RIKEN Nishina Center,
Tokyo Metropolitan University, SMI-ÖAW
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
2
3
introduction
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
η′ meson in vacuum
❖
m=958MeV/c2, Γ=0.2MeV
❖
peculiarly heavy among the pseudoscalar meson nonet
‣
“would-be” Nambu-Goldstone boson
‣
known as “η problem” in 1970’s (why not mη<√3̅mπ ?)
‣
axial U(1) anomaly in QCD
‣
related to spontaneous chiral symmetry breaking
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
4
pseudoscalar mesons in broken chiral symmetry
0
UA(1) anomaly
⇥, K,
8, 0
K
⇥, K,
8
massless
mq = ms = 0
mq = ms = 0
mq = ms = 0
q¯q⇥ = 0
⇥¯
q q⇤ = 0
⇥¯
q q⇤ = 0
ChS manifest
ChS broken dynamically
ChS broken dynamically
and explicitly
Nagahiro et al., PRC 87, 045201 (2013)
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
5
η′ meson in medium
❖
At finite density/temperature,
chiral symmetry will be partially restored
‣
cf. deeply-bound pionic atom
❖
large mass reduction, as a consequence of
suppression of the anomaly effect?
❖
optical potential: V(r)=(V0+iW0)ρ(r)/ρ0
‣
|V0|= (mass reduction), 2|W0|= (absorption width)
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
6
η′ optical potential: state of the art
-150
-100
-50 COSY-11 0
7
V0 [MeV]
(=mη′(ρ0)-mη′)
COSY-11
-10
CBELSA/TAPS
exp. (η′N int.)
theory
-20
chiral
unitary
NJL
linear σ
exp. (η′A int.)
QMC
W0 [MeV]
(=-Γ/2)
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
Nambu−Jona-Lasinio
model
s of the ’(958) meson
-150
mass of
-100presentation at-50
Nagahiro,
“Hadron
in Nucleus”
COSY-11
8
0
cf.) NJL model with KMT
V
(=m
2201(R)
13)
A(1)
’
800
Meson mass [MeV]
omaly
fect
600
UA(1) breaking
(KMT term[1,2])
-10
CBELSA/TAPS
400
chiral
unitary
200
sless
mically
oken
COSY-11
1000
[1] Kobayashi-Maskawa
PTP44(70)1422
[2] G. ’t Hooft,
PRD14(76)3432
-20
0
W
linear MeV @ QMC
Costa et al.,PLB560(03)171,
Nagahiro et al., PRC 76, 045203
(2006) (=-Γ
dyn.NJL
& explicitly
broken
Nagahiro-Takizawa-Hirenzaki, PRC74(06)045203
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
their result :
fm
fm
chiral unitary model
9
(2) Vector meson-baryon (VB) channel
-150
-100
-50 COSY-11 0
fm
their result :
V
Oset and Ramos, PLB 704, 334 (2011)
(=m
Nagahiro
et al., PLB
87 (2012)
(3) coupling
of 709,
the singlet
component of pseudoscalar to ba
phenomenological estimation for
COSY-11
Optical potential
B
[H.N., S. Hirenzaki, E. Oset, A. Ramos, PLB709(12)87]
-10
N
B
B
Kawaraba
fm
… free parameter
t
CBELSA/TAPS
chiral
unitary
presentation
at “Hadronpotential.
in Nucleus”
We consider onlyNagahiro,
the attractive
case & energy-independent
and
with various
values
fm
-20
in unit of MeV
0.1
0.3
NJL
linear
0.5
QMC
1.0
W
(=-Γ
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
r medium contains no explicit strange component. So,
mixing angle is approaching to a positive value wit
ange condensate is insensitive to the nuclear density.
partial restoration.
heless, the strange condensate does change slightly
h the SU(3) flavor breaking of nuclear matter.
IV. THE LOW-ENERGY η′ N INTERACTION IN VACU
xt, we show the result of the in-medium meson masses
ng the SU(3) breaking by the current quark mass in
Let us discuss the η′ N two-body interaction in vacuu
′
From this calculation, we find that the η mass reduces
the following, we estimate the η′ N interaction strength
ut 80 MeV at normal nuclear density. In contrast, the
the linear sigma model developed in the previous sectio
s of the other pseudoscalar octet mesons are enhanced.
evaluateSakai,
the invariant
amplitude
of the meson
and nucleo
presentation
at “Hadron
in Nucleus”
ally for the η case, the enhancement is about 50 MeV.
in the tree level by the scalar meson exchange and Born
because under the partial restoration of chiral symmetry
shown in Fig. 5:
gnitude of the spontaneous breaking is suppressed
and
• η’ mass in chiral limit
−iVab
+
+…
i
i
(0)
(8)
= gσ0 NN Cab
+ gσ8 NN Cab
1000
(k − k ′ )2 − m2σ0
(k − k ′ )2 −
linear sigma model
-150
-100
10
-50 COSY-11 0
V
(=m
In-medium meson mass(2)
M e so n M a ss [M e V ]
COSY-11
900
800
700
600
500
400
300
200
100
-10
mη ′
i
The contribution
The contribution
+ Ca γ5
C b γ 5 + Cb γ 5
/ +the
k/ −
mNsymmetry breaking p
/
from the UA(1) anomaly p
from
chiral
CBELSA/TAPS
chiral
unitary
mη
mπ
0
0.04
0.08
0.12
Nuclear Density [fm -3 ]
− k/′
− mN
Ca γ 5
The necessity of both the UA(1) anomaly and chiral symmetry breaking
for the generation of (c)
the η’ mass
(a)
(b)
Sakai and Jido, PRC 88, 064906 (2013)
-20
※The π mass vanishes in chiral limit
0.16
(mq→0)
14
. 3. The mass shift of the η′ meson in the nuclear medium.
id, dotted, and dashed lines represent the η′ , η, and π meson
in the nuclear medium, respectively.
NJL
i
linear σ
W
(=-Γ
FIG. 5. The diagrams that contribute to the η′ N interactio
dashed, single, and double lines mean the pseudoscalar m
nucleon, and scalar meson propagation, respectively.
QMC
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
quark-meson coupling model
-150
-100
-50 COSY-11 0
Bass and Thomas,
Etaprime˙mesic˙nuclei printed on December 20, 2013
Acta Phys. Pol. B 41 (2010) 2239;
arXiv:1311.7248
Physical masses fitted in free space, the bag masses in
7
medium at
ear-matter density, ρ0 = 0.15 fm−3 , and corresponding meson-nucleon
ngths.
η8
η (-10o )
η (-20o )
η0
η ′ (-10o )
η ′ (-20o )
m (MeV)
547.75
547.75
547.75
958
958
958
m∗ (MeV)
500.0
474.7
chiral
449.3
878.6
unitary
899.2
921.3
Rea (fm)
0.43 CBELSA/TAPS
0.64
0.85
0.99
0.74
0.47
11
V
(=m
COSY-11
-10
-20
W
NJL
linear
QMC
energy. The strange-quark component of the wavefunction does
to the σ field and η-η ′ mixing is readily built into the model. (=-Γ
uation and
centre-of-mass
effects
assumed
to be independent
Hiroyuki
Fujioka (Kyoto
Univ.),are
“GeV
領域光子で探るメソン生成反応の物理
” @ Tohoku Univ.
and of quantities derived from them are of the order of 20%.
are used to estimate the uncertainties: i
of 0.1 fm, the η′ width at ρ0 is of the
only 6% of it is due to two-body absor
taining a width as large 20 MeV, as fou
values of |aη′ N | of the order of 0.75 fm,
tributions of the one-body and two-body
turn out to be similar. We
consider
this /
CBELSA/TAPS
Collaboration
situation, providing a boundary for the d
this case the density dependence of the
by Γη1′+2 (ρ ) = Γη1′+2 (ρ0 )[ρ /ρ0 + (ρ /ρ0 )2 ]/
using this density dependence gives rise to
different values of Γη1′+2 (ρ0 ) as in Fig. 2
upwards. The best agreement with the
Γη1′+2 (ρ0 ) = 17–27 MeV. The similarity of
transparency ratio measurement
2.3. Results and discussion
Cross sections were measured for the four targets and the re-150
-100
-50 COSY-11 0
sulting transparency ratios were normalized to carbon, according
to Eq. (4). The transparency ratio as a function of the nuclear mass
number A is shown in Fig. 2 for three different incident photon
energy bins, namely: 1600–1800 MeV, 1800–2000 MeV and 2000–
2200 MeV. These curves are calculated using Eqs. (1) to (7) for
different values of the in-medium width Γη′ (ρ0 ) of the η′ -meson
in Eq. (7), ranging from 10 MeV to 40 MeV. The magnitude of Γ
A0 , the normal nuclear matter density, is used in what follows
at ρ
when we refer to the in-medium width.
transparency ratio
( A
T =
A· ( N
X)
X)
12
V
(=m
COSY-11
-10
CBELSA/TAPS
chiral
unitary
Fig. 6. (Left) Transparency ratio for different mesons – η (squares), η′ (triangles) a
cut on the kinetic energy for the respective mesons is shown with full symbols. Th
data. Only statical errors are shown. The impact of photon shadowing on the dete
not been corrected for in the published data for the other mesons. (Right) α param
η′ and ω ([34], this work). This figure is an updated version of a figure taken from
→ Γ=15−25MeV
at ρ=ρ0
-20
for <pη′>~1.05GeV/c
Γ
Because of the near constancy of
one would expect (see
′
Eq. (9)) a rise of σinel towards lower η momenta, as indicated
by the data in the lower panel of Fig. 5 (right). An increase o
σinel for low η′ momenta has in fact been predicted in [7], rathe
independent of the η′ scattering length. The theoretical predic
Fig. 2. Transparency ratio relative to that of 12 C, T A = T˜ A / T˜ 12 , as a function of the nuclear mass number A, for different in-medium width
tions follow qualitatively the trend of the data and may even be
incident photon energies. Only statistical errors are shown. The systematic errors are of the order of 20% but tend to partially cancel since cro
compatible with the experimental results, allowing for the large
systematic uncertainties in the determination of σinel due to the
領域光子で探るメソン生成反応の物理
unknown strength of two-body absorption processes, discussed
NJL
linear
QMC
Nanova et al., PLB 710, 600 (2012)
Hiroyuki Fujioka (Kyoto Univ.), “GeV
W
(=-Γ
” @ Tohoku Univ.
Fig. 5. (Colour online.) Differential cross sections for η′ photoproduct
(middle), and above the threshold (right). The calculations are for ση′ N
All calculated cross sections have been reduced by
CBELSA/TAPS Collaboration / Physics density,
Letters B respectively.
727 (2013) 417–423
excitation function and momentum distribution
-150
-100
-50 COSY-11 0
13
V
(=m
COSY-11
-10
′ photoproduc
Fig. 6. (Colour
Left:
for ηcross
Fig. 4. (Colour online.) Left: Total cross section for η′ photoproduction off C. The experimental
data areonline.)
extracted
byMomentum
integratingdistribution
the differential
sections
′
and
for
potential
depths
V
=
0,
−
25,
−
50,
−
75,
−
100
and
−
′ N =MeV
and by direct measurement of the η yield in the incident photon energy bins of width " E γ = 50 MeV (open circles). The calculations are for ση150
11
0.75
(see
text).
Middle:
The
experimental
data
and
the
predicted
curve
potential depths V = 0 MeV (black line), −25 MeV (green), −50 MeV (blue), −75 MeV (black dashed), −100 MeV (red) and −150 MeV (magenta) at nor
andis presented
linear scale.
The colour
code isonly
identical
to the o
density, respectively, and using the full nucleon spectral function. The dot-dashed blue curve
calculated on
for acorrelated
intranuclear
nucleons
(high-momen
contribution). All calculated cross sections have been reduced by a factor 0.75 (see text). scenarios.
Middle: The experimental data and the predicted curves for V = −25
−100 and −150 MeV divided by the calculation for scenario of V = 0 MeV and presented on a linear scale. Right: χ 2 -fit of the data with the calculated excitati
for the different scenarios over the full incident photon energy range.
V0=−(40±6) MeV
chiral
unitary
CBELSA/TAPS V0=−(32±11) MeV
Within the model used, the present results on the re
the potential are consistent with an attractive η′ ′ -nucle
be σinel = 11 mb, consistent with the result of transparency ranucleons contribute only about 10–15% to the η yield
tial with a depth of −(37 ± 10(stat) ± 10(syst)) MeV. T
cident energy regime above 1250 MeV. The observed cro
tio measurements [11]. The total nucleon spectral function is used
implies the first (indirect) observation of a mass redu
enhancement can therefore be attributed mainly to the
in the parametrisation given in [30]. Thereby, the contribution of
pseudoscalar meson in a strongly interacting environm
of the η′ mass in the nuclear medium.
η′ production from two-nucleon short-range correlations is taken
′
ρ
normal conditions (ρ =
′
0 , T = 0). The attractive η -nu
A real part of the η -nucleus potential depth between
into account. The calculations are improved with respect to [13]
tential might even be strong enough to allow the for
−25 MeV′ is confirmed by comparing the experimenta
as the momentum-dependent optical potential from [31], seen by
bound η -nucleus states. The search for such states is e
distributions with the corresponding calculations. Fig.
5
the nucleons emerging from the nucleus in coincidence with the
′ [11
η
by
the
relatively
small
in-medium
width
of
the
comparison for incident photon energy
ranges below, at a
η′ mesons, is accounted for as well.
ments are proposed to search for η′ -bound states via mis
the free production threshold, respectively. As for the
The calculations have been performed for six different scenarspectroscopy [35] at the Fragment Separator (FRS) at G
′ real potential at normal nuclear
function,
the highest sensitivity
to the potential
is
η
assuming
depths
of
the
ios
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理
” @ Tohoku
Univ. depth
a semi-exclusive measurement
at the BGO-Open
Dipol (
low incident energies, while at higher energies the mea
matter density of V = 0, −25, −50, −75, −100 and −150 MeV,
-20
V0=−(37±10stat±10syst) MeV
NJL
linear
QMC
Nanova et al., PLB 727, 417 (2013)
W
(=-Γ
P. Moskal et al.r Phy
elementary process : pp→ppη′
P. Moskal et al.r Physics Letters B 474 (2000) 416–422
COSY-11-50It
Moskal,
presentation at “Hadron
-150
-100 in Nucleus”
preliminary
pp→ppηꞌ
COSY-11 0
14
421
is interesting to note that in proton-proton
collisions at much higher momenta Ž450 GeVrc. the
h and hX mesons seem to have a similar production
mechanism which differs from that of the p 0 one
w48x. However, close to threshold the data show
similarities between hX and p 0 mesons rather than
between the h and hX .
V
(=m
COSY-11
Acknowledgements
1
σ=
F
We appreciate the work provided by the COSY
operating team and thank them for the good cooperation and for delivering the excellent proton beam.
The research project was supported by the BMBF
Ž06MS881I., the Bilateral Cooperation between Germany and Poland represented by the Internationales
____ J.P. Naisse, Nucl. Phys. A 278 (2997) 506
ŽPL-N-108-95
., and by the
DLR for
theZ.BMBF
¨ Druzhinin
---- Buro
B.L.
et al.,
Phys. A 359
(1997) 205
Ž41266606
. from the
FFE-grant
41266654
…. R. Shyam,
U. Mosel,
Phys. Lett and
B 436 (1998)
1.
Forschungszentrum Julich.
One of the authors ŽP.M..
¨
acknowledges financial support from the ForschungsX
0
ηFig.
zentrum
and
the
Foundation
for
Polish
Sci′N Julich
¨
h< <
p0<
h < <
.
<
.
<
5. The ratios of a M0 r M0 and b M0 r M0p < extrac
ence. from the data, assuming the pp-FSI enhancement factor depic
CBELSA/TAPS
Fig. 4. Total et
crossal.,
sections
for the
pp 416
pph reaction
as a
chiral
Moskal
PLB
474,
(2000)
function of the center-of-mass|M|
excess~ energy.
Open| squares and
|M | |M
w7x, respectively. Filled circles
triangles are from Refs. w8x and unitary
|Re
aη N|measurements
< 0.8fm
indicate the results of
the COSY-11
reported in this
2
dVps |M|2
X
0
2
FSI
2
′ |2 ~ |M |2 |M |2 |M |2
|M
pp givenp1η’
p2η’1.
numericalFSI
values are
in Table
letter. Corresponding
Statistical and systematical errors are separated by dashes. The
solid line shows the phase-space distribution with the inclusion of
proton-proton strong and Coulomb interactions.
-10
-20
γp→η′p @ LEPS2?
|a | ~ 0.1fm
QMC W
Moskal et al., PLB 482, 356 (2000)
(=-Γ
SOLID LINE (CFS)
DASHED LINE
|Re_a| = 0.3 +0.1 -0.2 [fm] |Re_a| = 0.2 +-0.2 [fm]
scattering
factorizing
p-p
0
Im_a
= -0.1length
+- 0.1 approximation,
[fm]
Im_aby= -0.0
+- 0.1 [fm]
by the dotted line in Fig. 2. < M0p < was calculated by interpolati
X
and h -p FSI, resulted in a rather modest estimation
the points of Fig. 4a.
X
Hiroyuki
Univ.),
“GeV 領域光子で探るメソン生成反応の物理
” @ Tohoku Univ.
of the
real partFujioka
of the (Kyoto
h -proton
scattering
length:
NJL
linear
η′ optical potential: state of the art
-150
-100
-50 COSY-11 0
|Re V| > |Im V|
search for η′
bound states!
NJL
linear σ
V0 [MeV]
(=mη′(ρ0)-mη′)
COSY-11
-10
V0=W
0
CBELSA/TAPS
chiral
unitary
15
QMC
exp. (η′A int.)
exp. (η′N int.)
theory
-20
W0 [MeV]
(=-Γ/2)
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
16
spectroscopy of η′ mesic nuclei at GSI
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
um level referred to as the UA !1" anomaly [1,2]. One
the huge !0 mass is believed to have a v
e most important subjects in hadron physics at present
tion to the UA !1" anomaly, the !0 mas
eveal the origin of the hadron mass spectra and to find
should provide us with important inform
he quantitative description of hadron physics from
tive
restoration
of the UA !1" symmetr
•
Egg
like
shape
LEPS2/BGOEGG
BGO-OD@ELSA
[3].
medium.
• TotalInvolume
cently, there have been several important developthis study, we consider missing m
s for the study of the spontaneous breaking of chiral
which
was proved to be a powerful to
• Total
weight
metry and its partial restoration at finite density. To only)
bound states formation in the studies
tigate the in-medium behavior of spontaneous chiral
pionic
• Two
typestates. In this spectroscopy, one
metry breaking, the hadronic systems, such as pionic photomultipliers
emitted particle in a final state, and o
s [4 –6], !-mesic nuclei [7–10], and !-mesic nuclei
differential cross section d2 $=d!=dE
–
11,12], have been investigated in both theoretical and
the emitted particle energy. In order to c
type)
imental aspects. Especially, after a series of deeply
priate reaction for this system, we show
–
d pionic atom experiments [13,14], Suzuki et al. re•
-region
d the quantitative determination of pion decay con500
(a) (γ,p)
f# in medium from the deeply bound pionic states in – Without housing material
otopes [5] and stimulated many active researches of – Only400with 3MBE=0
small
momentum
transfer
film
reflector.
artial restoration of chiral symmetry at finite density
pion
BE=50 MeV
300
15–17].
BE=100 MeV
wever, as detection
for the behavior
the UA !1"
of of
η→2γ,
6γ anomaly
by BGOin
BE=0
200
BE=150 MeV
uclear medium, the present exploratory level is rather
BE=50 M
(main
channel:
η′N→ηN)
Although
some decay
theoretical
results have
been re100
BE=100
pion
d, there exists no experimental information on the
BE=150
0
ble effective restoration of the UA !1" anomaly at fi0
2
4
6
8
0
2
Eγ [GeV]
density. Kunihiro studied the effects of the UA !1"
Fujiokaat(Kyoto
“GeV 領域光子で探るメソン生成反応の物理
” @ Tohoku Univ.
aly on Hiroyuki
!0 properties
finiteUniv.),
temperature
using the
q [MeV/c]
BGO EGG (γ,p)
photoproduction:
17
ρN
ρ(r) =
,
r−R
1 + exp( a )
1
3
12C(p,d)
(8)
reaction
where R = 1.18A − 0.48 fm, a = 0.5 fm with nuclear
number A, and ρN a normalization factor such that
!mass
d 3 rρ(r) = A. In the following sections, we show the (p,d)
spectra with potential depth from V0 = 0 to −200 MeV and
W0 = −5 to −20 MeV to discuss the observation feasibility,
where W0 is the strength of the imaginary part of the optical
potential at ρ0 .
Alternatively, we also use the theoretical optical potentials
for the η′ -nucleus system obtained in Ref. [19] by imposing
12 theoretical η′ N scattering lengths [20] and
11using the
several
standard many-body theory. There the two-body absorption
of the η′ meson in a nucleus together with the one-body
absorption has been evaluated so that we can decompose the
spectra into the different final states by using the Green’s
function method as discussed below.
We obtain the in-medium Green’s function by solving the
Klein-Gordon
equation with the optical potential Uη′ in Eq. (5)
❖
with the appropriate boundary condition and use it to evaluate
the nuclear response function R(E) in Eq. (1).
We❖estimate the flux loss of the injected proton and the
ejected deuteron due to the elastic and quasielastic scattering
and/or absorption processes by the target and daughter nuclei.
C
C
separation energy from the neutron single-particle level jn
Sn (ground) indicates the separation energy from the neutro
level corresponding to the ground state of the daughter nucleus
E0 is the η′ production threshold energy.
18
η’
intense proton beam available
FIG. 2. (Color online) Momentum transfer of the 12 C(p,d
reactions as functions of the incident proton kinetic energy Tp . Th
thick solid and dashed lines correspond to η′ meson production wit
binding energies of 0 and 100 MeV. Thin solid lines correspond t
η, ω, and φ meson productions with a binding energy of 0 MeV, a
indicated in the figure.
relatively large momentum transfer
‣
population of large ℓη′ states near threshold
045201-3
‣
different rigidities between protons and deuterons
(from an experimental point of view)
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
theoretical calculation
❖
elementary cross section : dσ/dΩ(pn→dη′)=30μb/sr
❖
relatively large momentum transfer
‣
19
population of large ℓη′ states near threshold
Nagahiro et al., PRC 87, 045201 (2013)
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
GSI accelerator facility
20
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
http://www.fair-center.eu
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
GSI-S437 experiment
22
!
4
1
0
2
Letter of Intent for GSI-SIS
,
y
l
u
Spectroscopy of
η
mesic nuclei
J
n
i
d
with
(p, d) reaction
e
l
u
d
e
sch
′
— Interplay of UA (1) anomaly and chiral restoration in η ′ mass —
Collaboration
K. Itahashi, HF et al., PTP 128, 601 (2012)
K. Itahashi1 , H. Outa,
Nishina Center for Accelerator-Based Science, RIKEN, 2-1 Hirosawa, Wako,
351-0198 Saitama, Japan
❖
❖
H. Fujioka2 ,
10
Division of Physics and Astronomy, Kyoto University, KitashirakawaOiwakecho, Sakyo-ku, 606-8502 Kyoto, Japan
intense proton beam from SIS-18 (~10 /spill)
H. Geissel, H. Weick3 ,
GSI - Helmholtzzentrum f¨
ur Schwerionenforschung GmbH, D-64291 Darm12
stadt, Germany
4g/cm2-thick C target
V. Metag, M. Nanova,
II. Physikalisches Institut, Universit¨at Gießen, D-35392 Gießen, Germany
❖
❖
R.S. Hayano, S. Itoh, T. Nishi, K. Okochi, T. Suzuki, Y. Tanaka
Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo, 1130033 Tokyo, Japan
high resolution measurement of deuteron by FRS
S. Hirenzaki, H. Nagahiro,
Department of Physics, Nara Women’s University, Kita-Uoya Nishi-Machi,
630-8506 Nara, Japan
2
overall missing-mass
resolution
:
σ
<
2MeV/c
D. Jido,
Yukawa Institute for Theoretical Physics, Kyoto University, KitasirakawaOiwakecho, Sakyo-ku, 606-8502 Kyoto, Japan
and K. Suzuki
Hiroyuki Fujioka (Kyoto
Univ.), “GeV
領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
Stefan Meyer Institut f¨
ur subatomare Physik, Boltzmangasse 3, 1090 Vienna,
experimental setup
2.5 G
eV p
23
S0-S2: momentum-compaction or achromatic
S0-S4: dispersive (~4cm/%)
roto
n
S1
12C
target
2.7-2
S2
S3
.9 Ge
V/c d
eute
ron
(pro
ton)
slit
plastic scintillator
S4
p/d separation
on-line: aerogel Cherenkov counter
MWDCx2, plastic scintillator,
off-line: TOF between S3 and S4
aerogel Cherenkov counter
(diff. by ~10ns)
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
expected spectrum w/ 4.5-day DAQ
285000
(V , W0)=−(150, 5) MeV
(V , W0)=−(100, 5) MeV
(V , W0)=−(200, 10) MeV
(V , W0)=−(150, 10) MeV
(V , W0)=−(100, 10) MeV
(V , W0)=−(200, 20) MeV
(V , W0)=−(150, 20) MeV
(V , W0)=−(100, 20) MeV
0
0
0
counts/2MeV
280000
(V , W0)=−(200, 5) MeV
24
275000
270000
265000
260000
285000
0
0
counts/2MeV
280000
0
275000
270000
265000
260000
285000
0
0
counts/2MeV
280000
0
275000
270000
265000
260000
255000
-40
-20
0
20 -40
-20
0
20 -40
-20
0
20
Excitation Energy [MeV] Excitation Energy [MeV] Excitation Energy [MeV]
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
structure-finding probability in GSI
20
100
25
(%)
90
18
80
|W | [MeV]
16
14
12
70
extend sensitivity in semi-
exclusive measurement at FAIR
60
50
40
10
30
20
8
10
6
60
80 100 120 140 160 180 200
|V | [MeV]
0
95% C.L., 4.5-day DAQ
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
FRS
optics
cs Simulation with GICOSY
o
30 dipole
target
S1
ton
am
S4
S3
S2
D1
e
26
D3
D2
ETA-S2-ACHR-5
X-direction
ETA-S2-ACHR-5
quadrupole
BEAM PLOT
EXPRESSION PLOT
SC1
D4
MWDC SC2 AC
XX.XX.XXX YY:YY:YY
X-MAX
0.240
X-MAX
0.200
m m
X-MAX 0.2 m
suppression of
“unphysical” BG at S2
XX.XX.XXX YY:YY:YY
MQMQ
MQMQ
MQMQ
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MQMQ
MQMQ
MQMQ
MQMQ
MAGNETIC
MAGNETIC
SECTOR
SECTOR
pro
gre
ss
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MQMQ
MQMQ
MQMQ
gicosy/
0.0
MQMQ
Y-MAX 0.200 m
%
5 cm/%
+5.00
MQMQ
[X,δ]
MQMQ
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MQMQ
MQMQ
MQMQ
MQMQ
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MQMQ
MQMQ
MQMQ
Dispersion
in
4 cm/%
large momentum
acceptance
= small dispersion
throughout FRS
+71.8 m
TA
S4
-5.00cm/%
-5
10 m
Expression:
10.000 m
10.000 m
9
[X,D]
Y.K. Tanaka, H. Weick
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
aerogel Cherenkov counter (HIRAC)
27
270×270×20 mm3 aerogel
pieces with n=1.168−1.174
manufactured by M. Tabata (Chiba U.)
mirror reflector
6080 white reflectance
or millipore, teflon
coating (Labsphere)
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
mini-HIRAC
28
will be installed at S2
for on-line p/d separation
(in the early stage of
beamtime)
60×60×20 mm3 aerogel
tics Simulation with GICOSY
pieces with n=1.183
30 dipole
target
o
S1
r
roton
]
eam
S4
S3
S2
D1
de
D3
D2
ETA-S2-ACHR-5
X-direction
ETA-S2-ACHR-5
quadrupole
BEAM PLOT
EXPRESSION PLOT
SC1
beam
D4
MWDC SC2 AC
XX.XX.XXX YY:YY:YY
XX.XX.XXX YY:YY:YY
X-MAX
0.240
X-MAX
0.200
m m
X-MAX 0.2 m
MQMQ
MQMQ
MQMQ
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MQMQ
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MQMQ
MQMQ
MQMQ
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MQMQ
pro
gre
ss
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MQMQ
MQMQ
MQMQ
MQMQ
MQMQ
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MQMQ
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MQMQ
5 cm/%
+5.00
MQMQ
[X,δ]
MQMQ
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MQMQ
MAGNETIC
MAGNETIC
SECTOR
SECTOR
MQMQ
MQMQ
Dispersion
in
4 cm/%
Y-MAX
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
Test Experiment @ COSY (Jülich)
MWDC
proton
2.738 GeV/c
1.471 GeV/c
29
MWDC
mini-HIRAC
HIRAC
TORCH
27/Jan − 10/Feb, 2014
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
30
semi-exclusive measurement at FAIR
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
http://www.fair-center.eu
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
from FRS to Super-FRS
target
FRS
proton
beam
o
30 dipole
S1
S4
S3
S2
D1
quadrupole
D2
D3
32
SC1
D4
MWDC SC2 AC
Super-FRS
target
dispersive
focal plane
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
(V0 , W0 ) = −(−42.8, 19.5) MeV [34], and the φ-nucleus optical
potential is (V0 , W0 ) = −(30, 10) MeV [35–38]. The thin solid line
shows the η′ production, and the dashed and dot-dashed lines indicate
the ω and φ meson productions. The contributions of mesonic states
with partial waves up to ℓ = 6 for each meson are included in the
calculation.
the experimental data [39]. As we can see in the figure, the
contribution from the φ meson is negligibly small owing to the
large momentum transfer for the φ meson production.
In contrast to the φ meson, we find that the ω meson
production gives larger contribution to the η′ bound region.
Although it is still unknown whether the ω-nucleus interaction
is attractive or repulsive, we consider the case that the
ω-nucleus optical potential is repulsive as Vω = −(−42.8 +
19.5i)ρ(r)/ρ0 MeV [34,40] because in the repulsive case the
quasifree ω contribution above the ω production threshold
is enhanced and then it overlaps the η′ bound region [15].
The elementary cross section of pn → dω in the laboratory
frame with Tp = 2.6 GeV is estimated as 27 µb/sr by using
the experimental data [41]. As shown in Fig. 5, although the
contribution of the quasifree ω is large, the strength of the
tail around the η′ threshold, where we can see the clear peak
coincidence of decay particles
❖
33
one-nucleon absorption: η′N→ηN, (πN)
LEPS2/BGOEGG, BGO-OD
two-nucleon absorption: η′NN→NN
η-PRiME@FAIR
this low-energy scattering wave of η′ closer to the daughter
nucleus, enhancing its overlap with the nucleon wave functions
and consequently producing a larger cross section. Therefore,
we can consider this enhancement to give an indication of
the❖attractive η′ -nucleus interaction if observed. We find
that, even in a large imaginary case of −(150, 20) MeV,
we can see a clear peak corresponding to this threshold
enhancement, indicating the attractive nature of the η′ -nucleus
optical ‣
potential. In the Appendix, we show various cases of the
higher energy than in any mesonic processes
Nagahiro et al., PRC 87, 045201 (2013)
FIG. 6. (Color online) Calculated spectra of the 12 C(p,d)11 C ⊗ η′ reaction for the formation of η′ -nucleus systems with proton kinetic
energy Tp = 2.5 GeV and deuteron angle θd = 0◦ as functions of the excited energy Eex . E0 is the η′ production threshold. The η′ -nucleus
optical potentials are evaluated in Ref. [19], which correspond to the η′ scattering lengths |aη′ p | = (a) 0.3, (b) 0.5, and (c) 1.0 fm, respectively.
The thick solid lines show the total spectra and dashed lines show subcomponents as indicated in the figure. The inset figure in panel (a) shows
the
structure of Fujioka
the subcomponents
in closeup.
Hiroyuki
(Kyoto
Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
high-energy protons from η′ mesic nuclei 34
p
d
η
100
d
π
p
d
N
×103
η′p→ηp
80
counts (a.u.)
p
p
Detection of high energy protons
(Tp= 300−600 MeV)
η′N→πp
η′pN→pN
60
40
20
0
0
100
200 300 400 500 600
proton kinetic energy [MeV]
700
800
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
high-energy protons from BG
35
×103
500
counts (a.u.)
400
300
200
100
η′p→ηp
η′N→πp
1
0
0
0.2
0.4
0.6
0.8
proton momentum
η′pN→pN
1
1.2
[GeV/c]
1.4
0.8
0.6
cos (Lab.)
0.4
0.2
simulation by a
microscopic
transport model (JAM)
0
-0.2
-0.4
-0.6
Y. Higashi
work in progress
-0.8
-1
0
0.2
0.4
0.6
0.8
1
1.2
proton momentum [GeV/c]
1.4
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
range counter for proton detection
❖
36
just conceptual…
‣
‣
‣
10 layers of Sci/Brass
sampling calorimeter
p/π separation by use
of neural network?
l
a
u
t
p
s
e
d
)
n
ig
e
c
on
(c
work in progress
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
37
inclusive measurement at FAIR
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
all-in-one readout board
❖
one order of magnitude
higher trigger rate
❖
R&D of 64ch readout
board for MWDC
38
‣
ASD + FlashADC + TDC
‣
originally developed
for Belle-II CDC
‣
sub-trigger module
for trigger distribution
H. Yamakami
Taniguchi et al., NIM A732, 540 (2013)
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.
Conclusion
❖
possible existence of η′-nucleus bound state, due to
partial restoration of chiral symmetry in medium
❖
inclusive measurement of (p,d) reaction at GSI/FAIR
❖
‣
high statistics and high resolution
‣
near-threshold structure = signature of attractive int.
‣
scheduled in 03.07.2014 − 09.07.2014 (GSI S437)
‣
DAQ upgrade in progress for higher statistics at FAIR
39
semi-exclusive measurement planned at FAIR
‣
high-energy proton from η′pN→pN in coincidence
Hiroyuki Fujioka (Kyoto Univ.), “GeV 領域光子で探るメソン生成反応の物理” @ Tohoku Univ.