JPARC Hadron physics WS 2014 11 30 What

J-PARC Hadron physics WS 2014. 11. 30 What can we learn about X resonances at K 1. 8 K. Imai (JAEA)

X resonances in PDG

PDG Table of X

X* quark model: Chao, Isgur, Karl PRD 23 (1981) X(1690)JP? X(1530)3/2+ X(1820)3/2 L(1520)3/2 L(1405)1/2 -

X* spectroscopy at K 1. 8 X*(1530) radiative decay X*(1690) Spin-parity, Branching ratio If ½-, it may be s=-2 analogue of L(1405). SK molecule?

Radiative decay of X(1530) is not known! • Radiative decay were measured for all other 10 -> 8 baryons. • Radiative decay is the best probe to study its structure.

X(1690) Why it is interesting? • Just below or above SK threshold S-K 0 1695. 0 Me. V S 0 K- 1686. 3 Me. V S 0 K 0 1690. 2 Me. V S+K- 1683. 1 Me. V • Very small branching to Xp • Narrow width ~10 Me. V candidate of exotic baryon (meson-baryon molecule)

Hyperon spectrometer (Hyp. TPC) for E 42, E 45 at JPARC TPC with GEM in Superconducting Helmholtz magnet of 1. 5 T 2021/12/11 Seoul-meeting 2010/11/30

2021/12/11

GEM sheet and the pad plane Test of full size TPC is under progress at JAEA 2021/12/11

Hyp. TPC • Target is inside TPC track of short life hyperons L, S , X-, (K 0) • High rate operation beam pass through up to 106 Hz (If GEM at beam path is killed, 107~108 Hz) • Large acceptance almost 4 p • High resolution DM(LL) ~ 1 Me. V 2021/12/11 Seoul-meeting 2010/11/30

X*(1530) X g • K-p -> K+ X-*(1530) ds/d. W ~ 40 mb/sr at p(K-) = 1. 65 Ge. V/c p(K+) ~ 700 Me. V/c T. Iijima et al. , (E 176) N. P. (1992) • Yield estimation 5 cm liq. H target, 106 K-/5 sec, 0. 1 str. Kurama acceptance, 100 shifts, 4. 6 x 105 X*-(1530) Hyp. TPC acceptance for X- p-L, L pp- 60% Charged branch of L : 64%, branch for radiative decay: 0. 5% 900 (3% error) If you require g position to reduce background 450 (5% error)

Mass spectra 1) X(1530) 2) X(1321) 3) L by S. Hwang • 1) • 2) 2)

Miss mass of p(K-, K+ X) gamma pi 0

HBC data on X(1690) P(K-)=4. 2 Ge. V/c (CERN) cross section for X(1690) ~ 7. 6 mb • C. Dionisi et al. , PL 80 B (1978) 145. • An enhancement at the Sigma K threshold (1680 Me. V) observed in K-p reactions at 4. 2 Ge. V/c. M(S+K-) M(LK-)

S. F. Biagi et al. , Z. Phys. C 34 (1987) 15. X* resonances in X- Be interactions • Width < 8 Me. V CERN 116 Ge. V/c X- beam

M. I. Adomovich et al. , WA 89 EPJ C 5 (1998) 621. First observation of X- p+ decay mode of the X 0(1690) hyperon. 345 Ge. V/c S- beam CERN 1400 events ! Width 10+-6 Me. V

K. Abe et al. , Belle PLB 524 (2002) 33. Observation of Cabbibo-suppressed and W exchange Lambda-c baryon decays. Lc X(1690)0 K+ at Belle. Width = 11+- 4 Me. V

Bar. Bar Lc L K 0 K+

spin of X(1690)

B. Aubert et al. , Bar PRD 78 (2008) 34008. Measurement of the spin of the X(1530) resonance. Lc X- p+ K+ at Bar

How can we measure with Hyp. TPC at K 1. 8 • Spin-parity and branching ratio to LK, SK, Xp, Xg • K-p -> K+ X-* -> LK-, S 0 K-, S-K 0, X-p 0, X 0 p-, X-g, • K-p -> K 0 X 0*, X 0* -> LK 0, S 0 K 0, S+K-, X-p+, • K 0 ->p+p-, X 0 ->Lp 0 Most of decay channels can be measured. (one neutral particle is allowed to reconstruct the decays ) Yield estimation: (5 cm liq. H, 106 K-/spill, 100 shifts) 4 mb 5 x 105 X*(1690) if 1 mb for each channel LK-, S 0 K-, Xp: 0. 6 x 0. 64=0. 38, -> 5 X 104 events S-K 0: 0. 35 x 0. 64 x 0. 6=0. 13 -> 1. 6 x 104 for K 0 X 0* channels, multiply 0. 35 x 0. 6=0. 2

mass spectra 1) X(1690) 2) L 3) X* 1) 3 2

How to determine spin-parity Angular distribution of decay particles !! 3/2 -> ½ +0 D-> p +N L=1 -> cosq But it is not so simple. for parity determination of ½ state. interference with background ( p(s)-wave resonance on s(p)-wave background) polarization of daughter hyperon (L, S) if X* is polarized (L(1405) Moriya et al. , )

Summary • The new hyperon spectrometer (Hyp. TPC) is under construction at JAEA in collaboration with Korea and New Mexico U. • Following H search experiment (E 42) and E 45, X* spectroscopy should be carried out as well as X-p scattering experiment at J-PARC. 2021/12/11

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Cross sections 3. 2+-0. 8 mb 1. 1+-0. 5 2. 3+-0. 3 1. 0+-0. 4 < 1. 0 • Xi-* • • Xi 0* • • Sigma 0 K- (K 0 pi+) Lambda K- (K 0 pi+) Sigma+ K- (K+, pi-) Lambda K 0 (K+, pi-) Xi pi • Total cross section for Xi(1690) 7. 6 mb

WA 89 setup S- 105/spill S-/p- =2. 3 7. 5 Tm 45 MWPC 29 SSD

E. Briefel et al. , PRD 16 (1977) 2706. Search for Xi* production in K-p interactions at 2. 87 Ge. V/c. sensitivity: 30 events/microbarn, BNL HB K-p K+ X- p+ X-p+ invariant mass