Kaonic nuclear state search by kaon reaction on He target...

M. Iwasaki

for E15 collaboration

Kaonic nuclear state search by kaon reaction on 3He

target at 1 GeV/c

11

MIN16 - Meson in Nucleus 2016, 31 Jul - 2 Aug

- Can kaon be a member of nuclei?- Kaon properties change in nuclear media?

ObjectivesKey questions :

χ-condensateNon-perturbative aspects @ energy < ΛQCD Finite density → sign problem Lattice-QCD approach difficult

Hadron masses and χ-symmetry

2

Search for Kaonic nuclear states

nuclear state search

3He(K-, n) @ 1 GeV/c

strongly attractive in I=0 channel

formation of high density matter?

K-pp• simplest system

BK ~ 50 MeV!

assuming Λ(1405) = K-p bound state …T. Yamazaki & Y. Akaishi, PLB 535 (2002) 70

3

T.Yamaga

◆ Recentresults

4

E-indep.

Reportsstructure /NOstructure

►Experiments►Theoreticalcalc.

KNinteractionmodelE-dep./E-indep.

J-PARC E15 1st

?

3He(K-, Λp)n:

with single pole assumption

Kpp should be studied moreE-dep.

5

Mðp!Þ # 2255 MeV=c2 of the K$pp candidate reportedby FINUDA [16].

The X production rate is found to be as much as the!ð1405Þð¼ !&Þ production rate, which is roughly 20% ofthe total ! production rate. Such a large formation istheoretically possible only when the p-p (or !&-p) rmsdistance in X is shorter than 1.7 fm [3,4], whereas theaverage N-N distance in ordinary nuclei is 2.2 fm. Thepp ! !& þ pþ Kþ ! Xþ Kþ reaction produces !&and p of large momenta, which can match the internalmomenta of the off-shell !& and p particles in the boundstate of X ¼ !&-p, only if X exists as a dense object. Thus,the dominance of the formation of the observed X at high

momentum transfer (#1:6 GeV=c) gives direct evidencefor its compactness of the produced K$pp cluster.As shown in Fig. 4, the peak is located nearly at the "!

emission threshold, below which the N"! decay is notallowed. The expected partial width of K$pp, #N"!, mustbe much smaller than the predicted value of 60 MeV [2],when we take into account the pionic emission thresholdrealistically by a Kapur-Peierls procedure (see [20]). Thus,#non-! ¼ #p! þ #N" ¼ #obs $ #N"! ( 100 MeV, whichis much larger than recently calculated nonpionic widthsfor the normal nuclear density, #non-! # 20–30 MeV[7,21]. The observed enhancement of #non-! roughly by afactor of 3 seems to be understood with the compact natureof K$pp [4].The observed mass of X corresponds to a binding energy

BK ¼ 103) 3ðstatÞ ) 5ðsystÞ MeV for X ¼ K$pp. It islarger than the original prediction [2,8,9]. It could beaccounted for if the $KN interaction is effectively enhancedby 25%, thus suggesting additional effects to be investi-gated [4,22]. On the other hand, the theoretical claims forshallow $K binding [10–12] do not seem to be in agreementwith the observation. We emphasize that the deeply boundand compact K$pp indicated from the present study is animportant gateway toward cold and dense kaonic nuclearmatter [15,23].We are indebted to the stimulating discussion of

Professors Y. Akaishi and R. S. Hayano. This researchwas partly supported by the DFG cluster of excellence‘‘Origin and Structure of the Universe’’ of TechnischeUniversität München and by Grant-in-Aid for ScientificResearch of Monbu-Kagakusho of Japan. One of us (T. Y.)acknowledges the support of the Alexander von HumboldtFoundation, Germany.

[1] Y. Akaishi and T. Yamazaki, Phys. Rev. C 65, 044005(2002).

[2] T. Yamazaki and Y. Akaishi, Phys. Lett. B 535, 70 (2002).[3] T. Yamazaki and Y. Akaishi, Proc. Jpn. Acad. Ser. B 83,

144 (2007); arXiv:0706.3651v2.[4] T. Yamazaki and Y. Akaishi, Phys. Rev. C 76, 045201

(2007).[5] T. Yamazaki et al., Hyperfine Interact. 193, 181 (2009).[6] M. Maggiora et al., Nucl. Phys. A835, 43 (2010).[7] M. Faber, A. N. Ivanov, P. Kienle, J. Marton, and M.

Pitschmann, arXiv:0912.2084v1.[8] N. V. Shevchenko, A. Gal, and J. Mares, Phys. Rev. Lett.

98, 082301 (2007); N.V. Shevchenko, A. Gal, J. Mares,and J. Révai, Phys. Rev. C 76, 044004 (2007).

[9] Y. Ikeda and T. Sato, Phys. Rev. C 76, 035203 (2007).[10] D. Jido, J. A. Oller, E. Oset, A. Ramos, and U.-G.

Meissner, Nucl. Phys. A725, 181 (2003); V. K. Magas,E. Oset, and A. Ramos, Phys. Rev. Lett. 95, 052301(2005).

[11] T. Hyodo and W. Weise, Phys. Rev. C 77, 035204 (2008).[12] A. Doté, T. Hyodo, and W. Weise, Phys. Rev. C 79,

014003 (2009).

0

0.5

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2150 2200 2250 2300 2350 2400 2450

2150 2200 2250 2300 2350 2400 2450

200 100 0

0

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1.5

2.0

2.5

3.0

3.5

(a) large-angle proton: high-P (p)

(b) small-angle proton: low-P (p)

Γ = 118 (8)

M = 2267 (2)

M = 2267 (2)

Missing Mass ∆M(K) [MeV/c ]2

Missing Mass ∆M(K) [MeV/c ]2

M(Λ

*+p)

= 2

345

M(Λ

*+p)

= 2

345

M(K

+p+p

) = 2

370

M(K

+p+p

) = 2

370

M(Σ

+π+p

) =

2267

M(Σ

+π+p

) = 2

267

Dev

iatio

nU

NC

/SIM

(arb

. sca

le)

Dev

iatio

nU

NC

/SIM

(arb

. sca

le)

B (K pp) [MeV]-

T

T

FIG. 4 (color online). (a) Observed DEV spectra of %MðKþÞof events with LAP emission [j cos"cmðpÞj< 0:6] and (b) withSAP emission [j cos"cmðpÞj> 0:6]. Both selected with large-angle Kþ emission [$ 0:2< cos"cmðKþÞ< 0:4].

PRL 104, 132502 (2010) P HY S I CA L R EV I EW LE T T E R Sweek ending2 APRIL 2010

132502-4

DISTO

present “Kpp" candidates @ BK~100 MeVhyper deep ??

Many objections exist, though…

J-PARK E27

M(Σ+π+p)

why no threshold (Σπp) effect seen?why no quasi-elastic K seen?

…p + p → p + N+(1710) → p + (Λ +K+)

→ (p + Λ) + K+ ??

M(K+p+p)

PublishedE151stdata

3He(K-,n)—semi-inclusive

3He(K-,Λp)n—exclusive

Only3days!(suspendedbytheearthquake)

6

PublishedE151stdata

3He(K-,n)—semi-inclusive

3He(K-,Λp)n—exclusive

Only3days!(suspendedbytheearthquake)

6withnewdata!

qK ~ 200 MeV/c

qK ~ 200 MeV/c

analyzedonlykinematically

AssumingaBreit-Wigner

8

• χ2-testwithpole&3NA(Ypn)– S-waveBreit-Wignerpole– w/Gaussianform-factor

B(X) ~ 15 MeVΓ(X) ~ 110 MeVQ(X) ~ 400 MeV/c

MΛp→

qΛp

→

9

Lorentzinvariantphase-space

Breit-Wigner

– introducesimplestassumptionS-wavepole&Breit-Wignerformula&Gaussianform-factor

form-factor2

stickingprobabilitytoharmonicoscillator

Assumingsinglepole(Breit-Wigner)

B(X) ~ 15 MeV, Γ(X) ~ 110 MeV, Q(X) ~ 400 MeV/c

ImprovingstatisticsviaE152nddataWhatisthestructurefoundinE151stdata?

~30timesmoredataforΛpnfinalstate

~6timesmoredataforforwardneutron

3days→3weeksw/higherprioritytoΛpinCDSE151st E152nd

MΛp→

Very Preliminary

11]2 [GeV/cM Λpinv.2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3

0

5

10

15

20

Cou

nts

per 2

0 MeV

/c2

data

sum

Multi-NA sum (w/o pole)

Λp invariant massM(K-+p+p)M(

M(Σ+π)Λ(1405)+p)

(x5)

E151standE152ndspectraconsistent?

MΛp→

]2 [GeV/cM Λpinv.2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 30

5

10

15

20

Cou

nts

per 2

0 MeV

/c2


M(Σ+π)Λ(1405)+p)

E15 1st

12


MΛp→

200

Cou

nts

per 1

0 MeV

/c2 E15 2nd

0

100

300

]2 [GeV/cM Λpinv.2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3


M(Σ+π)Λ(1405)+p)

E15 1st

13

Very Preliminary

YES!Theyareconsistent!


MΛp→

14

200

Cou

nts

per 1

0 MeV

/c2 E15 2nd

0

100

300

]2 [GeV/cM Λpinv.2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3


M(Σ+π)Λ(1405)+p)

E15 1st

E152ndspectrumdoesnotallowsinglepoleassumptionlooks like trapezoidal??

E151standE152ndspectraconsistent?YES!Theyareconsistent!

need further study

Very PreliminaryMΛp→

T.Yamaga

MENU2016@Kyoto

Inefficientregion Inefficientregion

15

KinematicalLimit

kinematical limitK-pp formation

ns

ps 2NA processwith spectatorns / ps

flat for point-like 3NACM

Is 3He point-like?

T.Yamaga

MENU2016@Kyoto

16

2NA

structure(s?)

PRELIMINARY

K- +“pp+ns”→Λp+ns

Λp invariant massVery Preliminary

MΛp→

3He(K-, Λp)n: Angular Dependence of n in CM

3He(K-, Λp)n: Angular Dependence

0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

forward n only

Very PreliminaryqΛp→

MΛp→


0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

countsper20MeV/c2

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

0

20

40

60

80

100

0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

M(

++p

)

M(K

+p+p

)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

0

50

100

150

200

250 !"!#$%%&%$'(!"!)*+

coun

ts p

er 2

0 M

eV/c

2

nwindow = 0.85 - 1.03 GeV/c 2

(CM)

countsper20MeV/c2

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

0

20

40

60

80

100


in more detailas a clue to understand


0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

coun

ts p

er 2

0 M

eV/c

2

0

20

40

60

80

100

120

140 !"!#$%$%#!"!'()

M(K

+p+p

)

M(

++p

)

*

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

(CM)

nwindow = 0.85 - 1.03 GeV/c 2

Very Preliminary


0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

coun

ts p

er 2

0 M

eV/c

2

0

20

40

60

80

100

120

140 !"!#$%##$&'!"!()*

M(K

+p+p

)

M(

++p

)

+

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

(CM)

nwindow = 0.85 - 1.03 GeV/c 2

Very Preliminary


0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

coun

ts p

er 2

0 M

eV/c

2

0

20

40

60

80

100

120

140 !"!#$%$%#!"!'()

M(K

+p+p

)

M(

++p

)

*

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

(CM)

nwindow = 0.85 - 1.03 GeV/c 2

Very Preliminary


0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

coun

ts p

er 2

0 M

eV/c

2

0

20

40

60

80

100

120

140 !"!#$%##$&'!"!()*

M(K

+p+p

)

M(

++p

)

+

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

(CM)

nwindow = 0.85 - 1.03 GeV/c 2

Very Preliminary


0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

coun

ts p

er 2

0 M

eV/c

2

0

20

40

60

80

100

120

140 !"!#$%$%#!"!'()

M(K

+p+p

)

M(

++p

)

*

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

(CM)

nwindow = 0.85 - 1.03 GeV/c 2

Very Preliminary


0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

coun

ts p

er 2

0 M

eV/c

2

0

20

40

60

80

100

120

140 !"!#$%%%$&'!"!()*

M(K

+p+p

)

M(

++p

)

+

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

(CM)

nwindow = 0.85 - 1.03 GeV/c 2

Very Preliminary

typical momentum transfer QK 400MeV/c~


two components exist?

bound region : forward peaking

weakly depend to cosθS-wave would be OK

unbound region :

very forward peaking

lower QK preferredbit strongly depend to cosθ

if that is the case,

Structure can be explained with quasi-elastic K scattering?

3He(K-, Λp)n:Not like semi-inclusive spectrum,

“quasi-free K” excluded by the final state: Λpn,

but still need to ask …

through uncorrelated Λ(1405)p channelSekihara Oset Ramos

3He(K-, Λp)n:

0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

M(

++p

)

M(K

+p+p

)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

0

50

100

150

200

250 !"!#$%%&%$'(!"!)*+

coun

ts p

er 2

0 M

eV/c

2

nwindow = 0.85 - 1.03 GeV/c 2

(CM)

countsper20MeV/c2

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

0

20

40

60

80

100

0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

3He(K-, Λp)n: Quasi-elastic?

simple QE?M

(+

+p)

M(K

+p+p

)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

0

50

100

150

200

250 !"!#$%%&%$'(!"!)*+

coun

ts p

er 2

0 M

eV/c

2

nwindow = 0.85 - 1.03 GeV/c 2

(CM)

A: Watson App.

Sekihara Oset Ramosuncorr. (1405) p

Very Preliminaryassuming uncorrelated Λ*p channel do not interfere with flat dist.

0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

3He(K-, Λp)n: Quasi-elastic?

M(

++p

)

M(K

+p+p

)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

0

50

100

150

200

250 !"!#$%%&%$'(!"!)*+

coun

ts p

er 2

0 M

eV/c

2

nwindow = 0.85 - 1.03 GeV/c 2

(CM)

B: Faddeev App.


simple QE?

Very Preliminaryassuming uncorrelated Λ*p channel do not interfere with flat dist.

Structure can be explained with “quasi-elastic K scattering” ? ➡ NO!

3He(K-, Λp)n:

Need deeper strength!

K multiple scattering = “Kpp”

Sekihara Oset Ramos

M(

++p

)

M(K

+p+p

)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

0

50

100

150

200

250 !"!#$%%&%$'(!"!)*+

coun

ts p

er 2

0 M

eV/c

2

nwindow = 0.85 - 1.03 GeV/c 2

(CM)

A: Kpp+Watson App. Sekihara Oset Ramos

3He(K-, Λp)n: comparison with SOR

0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

arXiv:1607.02058v1 [hep-ph] 7 Jul 2016

Very Preliminary

forward n only

QE + “Kpp”K multiple scattering

M(

++p

)

M(K

+p+p

)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

0

50

100

150

200

250 !"!#$%%&%$'(!"!)*+

coun

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er 2

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2

nwindow = 0.85 - 1.03 GeV/c 2

(CM)

B: Kpp+Faddeev App.

Sekihara Oset Ramos


0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

arXiv:1607.02058v1 [hep-ph] 7 Jul 2016

Very Preliminary

forward n only

QE + “Kpp”K multiple scattering

M(

++p

)

M(K

+p+p

)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

0

50

100

150

200

250 !"!#$%%&%$'(!"!)*+

coun

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eV/c

2

nwindow = 0.85 - 1.03 GeV/c 2

(CM)

A: Kpp+Watson App. B: Kpp+Faddeev App.

Sekihara Oset Ramos


0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

arXiv:1607.02058v1 [hep-ph] 7 Jul 2016Qualitatively

in good agreement!

calculated without knowing E15 2nd spectrum

forward n only

Very Preliminary

Structure can be explained with quasi-elastic K scattering & Kpp @ -UM?

3He(K-, Λp)n:

Need even deeper strength!

How to understand whole structure?

χ

qualitatively YES! but …

K-+d n+Λ(1405)

37

E31:K-+d n+Λ(1405)

Λ(1405) Σ±π ±

1.51.41.3[GeV/c 2].Minv

E31

yiel

d charge mode average

Very Preliminary

Λ(1405) Σ±π ±

Very Preliminary

K-+d n+Λ(1405)

37

E31:K-+d n+Λ(1405)

Λ(1405) Σ±π ±

1.51.41.3[GeV/c 2].Minv

E31

yiel


Very Preliminary

Λ(1405) Σ±π ± coun

ts p

er 2

0 M

eV/c

2

0

20

40

60

80

100

120

140!"!#$%%%$&'!"!()* +

(CM)

2.2 2.4 2.6[GeV/c 2]p.Minv

E31

Note: very forward n only

E15

Very Preliminary

K-+d n+Λ(1405)

37

E31:K-+d n+Λ(1405)

Λ(1405) Σ±π ±

1.51.41.3[GeV/c 2].Minv

E31

yiel


Very Preliminary

Λ(1405) Σ±π ± coun

ts p

er 2

0 M

eV/c

2

0

20

40

60

80

100

120

140!"!#$%%%$&'!"!()* +

(CM)

2.2 2.4 2.6[GeV/c 2]p.Minv

E31

Note: very forward n only

E15

Very Preliminary

larger Fermi-motion?

“Kp” → “Kpp”?

0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

M(

++p

)

M(K

+p+p

)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

0

50

100

150

200

250 !"!#$%%&%$'(!"!)*+

coun

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er 2

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eV/c

2

nwindow = 0.85 - 1.03 GeV/c 2

(CM)

Very Preliminary

How to understand whole structure?

from the shape of deeper region

(sharp drop), the structure in bound

region must be narrow ( 60MeV)~

3He(K-, Λp)n:

0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

3He(K-, Λp)n: QE + ?

M(

++p

)

M(K

+p+p

)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

0

50

100

150

200

250 !"!#$%%&%$'(!"!)*+

coun

ts p

er 2

0 M

eV/c

2

nwindow = 0.85 - 1.03 GeV/c 2

(CM)

B: Faddeev App.


simple QE+?

Very PreliminaryIs there No interference?

0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

3He(K-, Λp)n: QE + Kpp

if we can neglect interference

rather deep &narrow in width

K-pp?

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

0

50

100

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200

250 !"!#$%%&%$'(!"!)*+

coun

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2

nwindow = 0.85 - 1.03 GeV/c 2

(CM)

K elastic?B: Faddeev App.

Sekihara Oset Ramosuncorr. (1405) psimple QE

+Kpp?

K quasi-elastic?

Very Preliminary

3He(K-, Λp)n:

countsper20MeV/c2

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

0

20

40

60

80

100

120

140

160

180

200

3He(K-, Λp)n:

if we can neglect interference

rather deep &narrow in width

could be OK

0.0

0.5

1.0

ccoossnnθθ(CM)

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c2]ΛΛp.Minv

coun

ts p

er 2

0 M

eV/c

2

2.0 2.2 2.4 2.6 2.8 3.0[GeV/c 2]p.Minv

0

20

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200!"!#$%$'&!"!()* +

(CM)

nwindow = 0.85 - 1.03 GeV/c 2

K-pp?

K elastic?B: Faddeev App.


Very Preliminary

K quasi-elastic?

T.Yamaga

◆ Recentresults

43

E-indep.

Reportsstructure /NOstructure

►Experiments►Theoreticalcalc.

KNinteractionmodelE-dep./E-indep.

J-PARC E15 1st

J-PARC E15 2nd??

?

3He(K-, Λp)n:

could be the first convincing data… after a long journey …

with single pole assumption

with double structuresVery Preliminary

E-dep.

Summary

first convincing Kpp signal

finish analysis, including

probably, BK ~ 100 MeV would be excluded

low qK is key for the formation

cf. arXiv:1607.02058 → MΛp = 2354 − 36i MeV B(K) ~ 15 MeVΓ(K) ~ 70 MeV

compact system ?QK ~ 400 MeV/c → ~ 0.5 fm?

44

deeper than -UM ? χ

what needed to be finalize?

examine other possibilities: uncorrelated Σ* p?

full kinematical refit / angular distributions …further theoretical inputs?

what is flat dist. over Dalitz?Λpn

E31?

JP?

THANKS

46

backups

47

15m

E15

J-PARC47

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1.0

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[GeV/c

2 ]M(Xmiss)

[GeV/c 2]p.Minv48

K- + 3He → ? → Λ + p + n

Y (=K-pp) → Λ + p K- + 3He → Y + n

n-window

nγ m

iss.

(n p

Σ0 )

n miss.

(n p Λ

)

invariant mass of(Λ p) system

mass of missing particle

M(K

+p+p

)

M(Σ

+π+p

)

nπ m

iss.

(n p Λπ

)

M(Λ p)

M(X

mis)K- + 3He → Λ + p + Xmis (Xmis=n)

48

Very Preliminary

T.Yamaga

MENU2016@Kyoto

2016.07.2650

2NAprocess

Structure

CMframe

Beam

PRELIMINARYK-+3He:K- +“pp+ns”→Λp+ns

backwardVery Preliminary

kinematically forbidden

qX dependence

twocomponents?

with different qX?

Very Preliminary

51

M(K

+p+p

)

smaller QX?

larger QX?



kinematically forbidden kinematically

forbidden

(40 MeV bin)slice =

0.1 GeV/c

Very Preliminary52

3He(K-, Λp)n T. Hashimoto et al., PTEP (2015) 061D01.B(X) ~ 15 MeVΓ(X) ~ 110 MeVQ(X) ~ 400 MeV/c

E151st

E152ndB(X) ~ 50 ?? MeVΓ(X) ~ 60 ?? MeVQ(X) ~ 400 ?? MeV/c

two structures & Kpp for deeper one!!… very deep

… very compact ( < 0.5 fm ? )

remaining mystery “point like reaction in Λpn final state”

53

Λpn : single-pole?Y. Sada et al., PTEP (2016) 051D01.

n : semi-inclusive

(not hyper deep, though)

… rather narrow

Very Preliminary

❖ Mass :❖ Width :❖ Binding Energy

ΣN cusp +  ΣN→ΛN conversion

�⇤p�⌃0p

= 0.92+0.16�0.14(stat)+0.60�0.42(syst)

Prelimin

ary

PTEP 2015, 021D01 Y. Ichikawa et al.

(a) (b) (c)

Fig. 3. Missing-mass square spectra of X obtained in two-proton coincidence events in thed(π+, K + pp)X reaction. Each spectrum shows the mass square of X for a different MMd region: theleft (a) shows the QF" region (MMd < 2.22 GeV/c2), the center (b) shows the “K − pp”-like structureregion (2.22 < MMd < 2.35 GeV/c2), and the right (c) shows the QFY ∗ region (MMd > 2.35 GeV/c2). Thespectra were fitted with three components of #p (dashed line), "0 p (dot-dashed line), and Yπp (dotted line)decay modes.

two-proton coincidence events of the "0 p final state (ii) with the acceptance correction. According tothe simulation, the contribution of the "0 p → "0 p rescattering background is negligible because ofthe two high-momentum proton coincidence. The spectrum was fitted with a relativistic Breit–Wignerfunction:

f (MMd) =(2/π)MMdm0$(q)

(m20 − MM2d)2 + (m0$(q))2. (2)

The mass-dependent width was $(q) = $0(q/q0), in which q (q0) is the momentum of the"0 and proton in the "0 p rest frame at mass MMd (m0). The obtained mass and width are2275 +17−18 (stat.)

+21−30 (syst.) MeV/c

2 and 162 +87−45 (stat.)+66−78 (syst.) MeV, respectively. This cor-

responds to the binding energy of the K − pp system of 95 +18−17 (stat.)+30−21 (syst.) MeV and the

production cross section of the “K − pp”-like structure decaying to "0 p of dσ/d&K − pp→"0 p =3.0 ± 0.3 (stat.) +0.7−1.1 (syst.) µb/sr. The systematic errors of these values were estimated taking intoaccount uncertainties in the fitting ranges, the binning of the missing-mass spectrum, the detec-tion efficiency of two protons in the RCA, and the Breit–Wigner shape by changing the Lorentzianfunction folded with the missing-mass resolution. The differential cross section of the “K − pp”-like structure of the #p decay mode (i) was also estimated from the fitting assuming the samedistribution of MMd . Thus, a branching fraction of the “K − pp”-like structure was obtained as$#p/$"0 p = 0.92 +0.16−0.14 (stat.)

+0.60−0.42 (syst.). This ratio was discussed from a theoretical point of

view and predicted to be 1.2 using the chiral unitary model in Ref. [27].Next, we try to understand the ratio histogram (Fig. 2(c)) with the obtained K − pp mass distribution

of f (M Md). By using the mass distribution for the “K − pp”-like structure and the double-differentialcross section of the inclusive (π+, K +) process d

2σd&d M Md

(M Md)inclusive, we can obtain the ratio

6/8

at Library of Research Reactor Institute, Kyoto U

niversity on February 25, 2015http://ptep.oxfordjournals.org/

Dow

nloaded from

162+87�45(stat.)+66�78(syst.) MeV

2275+17�18(stat.)+21�30(syst.) MeV/c

2Λp/Σ0pK-pp-like structure in Σ0p

Σ0pΛp

T. Nagae

Mthr.(Σπp)

Mthr.(Kpp)

Nothresholdeffectseen?!54

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