Photoproduction of and (1520,1405) Seung-il Nam Yukawa Institute - - PowerPoint PPT Presentation

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Photoproduction of and (1520,1405) Seung-il Nam Yukawa Institute - - PowerPoint PPT Presentation

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YITP, Kyoto University Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan Photoproduction of and (1520,1405) Seung-il Nam Yukawa Institute for Theoretical Physics (YITP), Kyoto University, Japan In collaboration with A.Hosaka

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Photoproduction of Φ and Λ(1520,1405)

Seung-il Nam

Yukawa Institute for Theoretical Physics (YITP), Kyoto University, Japan

In collaboration with A.Hosaka (RCNP), D.Jido (YITP), and H.C.Kim (Inha Univ.)

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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Introduction

Nucleon (N) and hyperon (Y) resonance searches

  • Insight to hadron structures and production mechanisms
  • Completion of hadron spectrum
  • Strangeness physics from Y-resonances
  • Exotic baryon searches: petanquark baryon

Experiments

  • LEPS, Tohoku-LNS, CLAS, GRAAL, BONN-ELSA etc..
  • η, K and φ photo- and electro-productions
  • N*(1535), Σ*(1385), Λ*(1405), Λ*(1520) etc..
  • Exotics: N*(1675) from LNS and GRAAL, and Θ(1540) from LEPS

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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Intr Introduction

  • duction

Theories

  • Coupled channel methods: dynamical generation of resonances
  • Effective Lagrangian methods: resonances as element fields
  • Baryonic models: Skyrmion with excitation, CQSM, etc..

Resonances via three-body final state

  • Three-body final state LIPS
  • Dalitz-plot analyses for a,b → 1,2,3
  • Resonances appear as strips

a b 3 1 2 a b 3 1 2

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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Intr Introduction

  • duction

Interference between resonances

  • Constructive intereference → enhancing signal
  • Sensitive to relative phase, strength, etc..

Low statistics in exotic baryon search

  • Small coupling strength of Θ→KN ~ 1 MeV
  • σ(γΝ→KΘ) ~ a few nb: hard to be seen in production processes
  • Strong constructive interference on Dalitz plot!?Amarian et al. hep-ph/0612150

False signals

  • Resonance-like structure generated from kinematical reasons
  • Resonance contribution + phase space

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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Introduction

A model calcaultion to test these topics (intereference & false signal) Basic studies for further researches on resonances Theoretical method

  • Considering γp→K+K-p containing Λ(1520) and φ(1020)
  • Considering the LEPS experimental setup: K+ only in forward angle
  • Employing an effective Lagrangian method
  • Form factors in a gauge-invarinat manner
  • Finally, plotting Dalitz plots

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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Theor heoretical fr etical framew amewor

  • rk

Feynman diagrams

  • For the intereference pattern: Λ(1520)=Λ* and φ(1020) contribution only
  • Red blob contains s-,t-,u-channels and contact term: gauge invariant
  • Green blob contains s-,t-,u-like channels, contact term: gauge invariant
  • Blue blob contains Fµν: gauge invariant itsself and pomeron effect
  • Photon-Λ* coupled diagram ignored: neutral and no data for κ for Λ*
  • K*-exchange contribution ignored: g(K*NΛ*) << 1

γ p p K+ K- γ p p K+ K- γ p p K+ K-

Λ Λ φ

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 7

Theor heoretical fr etical framew amewor

  • rk

Effective Lagrangians

  • Λ* cotnribution (Λ*=B*)
  • Rarita-Schwing vector-spinor fields for Λ*
  • Λ*(spin-3/2) propagator ~ spin-1/2 propagator for low-energy region
  • g(KNΛ*) obtained from exp. data

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 8

Theor heoretical fr etical framew amewor

  • rk

Effective Lagrangians

  • φ contribution
  • Pomeron contribution taken into account in F(s,t)
  • Reproduction of strong forward scattering

A.I.Titov et al PRC58,2429

  • Model parameters fitted by data

γp→φ →φp

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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Theor heoretical fr etical framew amewor

  • rk

Three-body LIPS and double-differential cross section

  • LEPS kinematics simplifies computation significantly: kK/|kK| ~ kγ/|kγ|
  • Inner-products, kK•εγ and kp•εγ become zero in CM frame
  • Definition of relevant momenta

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 10

Theoretical framework

Conditions for the Dalitz plot

  • Maximum and minimum, confining Daitz region
  • Angle between final kp and z-axis

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 11

Numercal results: interference

Dalitz plots for γp→K+K-p

Eγ=2000MeV Eγ=2100MeV Eγ=2050MeV

  • Triple-differential σ [µb/GeV]
  • Small interference effect

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 12

Numercal results: interference

Dalitz plots for γp→K+K-p

Eγ=2000MeV Eγ=2100MeV Eγ=2050MeV

  • Small interference effect
  • σφ < σΛ(1520)
  • Insensitive to relative phase

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 13

Numercal results: false signal

Dalitz plots for γp→K+K-p with only φ contribution

Eγ=2010MeV

  • B.G. contribution + phase space
  • False sigal at low-energy region
  • Depending on experimental resolution?

a b 3 1 2

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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Summary and conclusion

Studies on three-body final state using Dalitz plot γp→K+K-p containing Λ(1520) and φ(1020) Effective Lagrangian method employed Intereference effect

  • Sensitive to strength and/or phase
  • Negligible effects on γp→K+K-p due to σφ < σΛ(1520)
  • If, in γn→K+K-n, σφ ~ σΘ at low energy region, the effect becomes visible

False signal

  • B.G. contribution + phase space without resonances
  • Possible for low-energy region with coarse resolution
  • Sensitive to strength and/or phase

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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Theor heoretical sta etical status tus

Λ(1405) KN bound state rather than a uds color singlet!? cf) N*(1535) Energetic activities on Λ(1405) studies

  • Two-pole structure Spain and Japan groups
  • Different microscopic structure: larger size Sekihara et al, PLB** [arxiv:0803.4068 [nucl-th]]
  • Studies on the origin of s-wave resonance Hyodo et al, PRC78,025203
  • Three-body problems KKN-molecular state D.Jido et al, arXiv:0806.3601 [nucl-th

Λ(1405) nature via meson and photon induced reactions

  • γN→KΛ(1405) Williams et al, PRC43,452
  • Production mechanism SiN et al, arXiv:0806.4029 [hep-ph]

Focusing on the photoproduction

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 16

Experimental sta Experimental status tus

Meson-nucleon scattering

  • K--N scattering Hepp NPB115,82, Hermingway NPB253,742, Prakhov PRC70,034605
  • π--p scattering Thomas NPB56,15

Photon-nulceon scattering

  • γ-p scattering (by LEPS) J.K.Ahn NPB721,715c, Niiyama et al, PRC78,035202

Main difference between the two photoproduction data

K+

Target

π

Spectrometer

J.K.Ahn, NPB721,715c (2003) Niiyama,PRC78,035202 (2008)

K+

Target

π

Spectrometer

TPC

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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Experimental sta Experimental status: tus: ang angle dependence le dependence

Pion measured in wider angle by TPC Angle-dependent production becomes critical in the new experiment K+ missing mass in γp→ K+X Significant difference between π+Σ- and π-Σ+ channels Indicating sizable p-wave contribution in Λ(1405) photoproduction!?

K+ π

Niiyama, PRC78,035202

Forward Forward

Niiyama et al, PRC78,035202 J.K.Ahn, NPA721,715c

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 18

Experimental sta Experimental status: tus: ener energy dependence y dependence

γp→ K+Λ(1405) cross section estimated in the new exp. σ[Σ(1385)] ~ 0.6 µb for Rg.1 σ[Σ(1385)] ~ 0.5 µb for Rg.2 σ[Λ(1405)] ~ 0.3 µb for Rg.1 σ[Λ(1405)] ~ 0.04 µb for Rg.2

Y.Oh, PRC77,045204

Factor ~ 8 difference!

Eγ=2.4 Eγ=1.5 Eγ=2.0 σ[Λ(1405)] σ[Σ(1385)] ~ 0.54 σ[Λ(1405)] σ[Σ(1385)] ~ 0.084

Niiyama, PRC78,035202

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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Theor heoretical anal etical analysis ysis

Possible p-wave contribution in Λ(1405) mass spectrum Employing the ChUM with explicit p-wave contribution from Σ*(1385) Λ(1405) photoproduction with s-wave by Nacher et al. Nacher,PLB455,55 Considering the LEPS experimental setup: K+ in forward angle (θK~0) Diagrams considered

T

Σ K+ p π γ Σ K

+

p π γ

Σ*

Σ K+ p π γ

Σ*

Nacher,PLB455,55

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 20

Theor heoretical anal etical analysis ysis

ΦB→ΦB amplitude ( ) including (s,p)-wave contributions Jido,PRC66,055203 Lagrangians for the interaction vertices Interaction kernels Unitarization

T

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 21

Theor heoretical anal etical analysis ysis

Λ(1405) photoproduction with (s,p)-wave contribution Unitarized amplitude ΦB→ΦB total amplitudes ΦB→ΦB element amplitudes

T

Σ K+ p π γ Σ K

+

p π γ

Σ*

Σ K+ p π γ

Σ*

s-wave s-wave p-wave

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 22

Numerical r Numerical results esults

Λ(1405) photoproduction via γp→K+πΣ at Eγ=1.7 GeV

A:Σ+π- B:Σ-π+

B A A B

Niiyama, PRC78,035202 J.K.Ahn, Challenge to New Exotic Hadron at RCNP, 2008

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 23

Numerical r Numerical results esults

Λ(1405) photoproduction via γp→K+πΣ at Eγ=2.2 GeV

A:Σ+π- B:Σ-π+

Niiyama, PRC78,035202

Strength of MπΣ

  • Theory: increasing
  • Experiment: decreasing

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 24

Numerical r Numerical results esults

Λ(1405) photoproduction via γp→K+Λ(1405) SiN et al, arXiv:0806.4029 [hep-ph] Usual approaches can not reproduce the data Indication of a strong resonance near the threshold? cf) KKN molecular state D.Jido et al, arXiv:0806.3601 [nucl-th]

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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SLIDE 25

Numerical r Numerical results esults

Λ(1405) photoproduction via γp→K+Λ(1405) SiN et al, arXiv:0806.4029 [hep-ph] Considering resonances and two-pole structure |Λ(1405), Phys〉 = a|high-Λ(1429)〉+b|low-Λ(1392)〉+c|uds,I=0〉+.. |high-Λ(1429)〉 and |low-Λ(1392)〉 : KN-bound state |uds, I=0〉 : NR-quark model (close)

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

Relative phase between the hign and low ~ -1 (in ChUM by D.Jido) Destructive interference between them!

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Summar Summary and per y and perspectiv spective e

Λ(1405) photoproduction investigated to interpret recent LEPS with TPC ChUM with s- and p-wave (Σ*1385) contributions Possible explanations

  • Other p-wave contributions: ground-state Y, M-B-loop contributions
  • Larger K+ angle: 0 < cosθK < 1
  • Resonance contributions & destructive interference of two-pole cont.
  • Λ(1405): mixture of various states: experimental evidence?
  • How about Λ(1520)??

Theory (ChUM) Experiment Σ-π+ vs. Σ+π- Σ-π+ ~ Σ+π- Σ-π+ > Σ+π-: Niiyama (Σ-π+ ~ Σ+π-: J.K.Ahn) Energy dependence Increasing Decreasing Σ*(1385) contibution Strong Weak

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan

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Thank you very much for your attention!! Special thanks to

T .Nakano, J.K.Anh, M.Niiyama, and H.Kohri

YITP, Kyoto University

Strangeness in Multiquark Systems, 27~28 Feb 2009, Atami, Japan