Chiral dynamical aspects of recently measured (low energy) reactions - - PowerPoint PPT Presentation

η photoproduction on proton and neutron π0η photoproduction

Chiral dynamical aspects of recently measured (low energy) reactions at MAMI, ELSA, GRAAL, and other labs

• M. Döring

Helmholtz-Institut für Strahlen- und Kernphysik (HISKP), Universität Bonn

Hadron 2011 (München) 13.-17.06.2011

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

Excess of ηn production

The reactions γp → ηp and γn → ηn on free and quasi-free nucleons in the deuteron 700 800 900 1000 1100 1200 Eγ [MeV] 5 10 15 σ [µb]

free ηp quasi-free ηp quasi-free ηn s

1/2=1535 MeV

s

1/2=mN+mη

free ηp: CBELSA & TAPS, CLAS, LNS quasi-free ηN: CBELSA & TAPS (Jaegle et al.)

◮ η excess on n found at Graal

[Kuznetsov et al., PLB 647 (2007)].

◮ Confirmed by CBELSA & TAPS

[Jaegle et al., PRL 100 (2008)]; LNS [Miyahara et al.,PTPS 168 (2007)].

◮ Some concepts: [Talks of the “Narrow Nuclear Resonances”

conference, Edinburgh 06/2009] ◮ Non-strange pentaquark, χQSM

prediction

[Diakonov et al. ZPhysA 359 (1997), Polyakov et al.,EPJA 18 (2003),...]. ◮ Prediction of narrow P11 resonance in πN Arndt et al., PRC 69 ◮ S11(1650)/P11(1710) interference effect [Shklyar, Lenske, Mosel, PLB 650 (2007)]. ◮ Interference of various partial waves [Shyam et al., arXiv:0808.0632, Choi et al., PLB 363 (2006)]. ◮ D15(1675) [ηMAID, NPA 700 (2002)]

• r P11 [Fix et al., EPJA 32 (2007)]?

◮ Around 80 % of σp is S-wave; and σn?

P-wave? Polarization data

[Kuznetsov, Polyakov et al., APPolonB 39,...(2008)]

S-wave dominance (?)

[Anisovich et al., EPJA 41 (2009), Miyahara et al.,PTPS 168 (2007)]. München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

Coupled channels and unitarity

• N. Kaiser et al., PLB 362 (1995) 23, NPA 612 (1997) 297,
• T. Inoue et al., PRC 65 (2002) 035204

Nieves, Ruiz Arriola, PRD 64 (2001) García Recio, Lutz, Nieves, PLB 582 (2004)

◮ (0−)M ⊗ (1/2+)B in SU(3): Coupled channels in S = Q = 0 are

πN, ηN, KΣ, KΛ.

◮ Interaction V from the LO chiral Lagrangian:

(Isovector) Weinberg-Tomozawa interaction.

◮ Unitarization through the Bethe-Salpeter equation

Loop G

T = (1 − VG)−1 V. “=”

◮ Strong channel coupling. ◮ Attraktion + Unitarization → Pole in the scattering amplitude.

Dynamically generated N∗(1535) (not the main issue here).

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

Photon coupling to the coupled channels

Formalism along the lines of [Haberzettl, Nakayama, Krewald, PRC 56 (1997), PRC 74 (2006)]

◮ Electromagnetic properties provide independent tests, because the

couplings of the photon to the mesons & baryons are well known. Predictions of, e.g., helicity amplitudes [D. Jido, M. D., E. Oset, PRC77 (2008)].

(a) (b)

• 1. γp, γn initial state.
• 2. Excitation of intermediate meson-baryon states MB (πN, ηN, KΛ, KΣ).
• 3. Superposition of initial (MB)initial → MBfinal.
• 4. MBfinal = πN, ηN, KΛ, KΣ.

Details/other results

◮ Global fit to 18 reactions (Multipoles & partial waves):

γN, πN → ηN, πN, KΛ

◮ Gauge invariance ensured.

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

η photoproduction on free p and n

• M. D., K. Nakayama, PLB 683 (2010)

700 800 900 1000 1100 1200 Eγ [MeV] 5 10 15 20 σ [µb] KΣ KΛ

Data: Jlab-Clas, Bonn CB-Elsa, LNS [Recent high precision MAMI data not yet included (PRC 82, 2010)].

Solid: γp → ηp Dotted: γn → ηn

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

η photoproduction on quasi-free p and n

Inclusion of Fermi motion in the deuteron in a spectator model.

700 800 900 1000 1100 1200 Eγ [MeV] 5 10 15 20 σ [µb]

s

1/2=1535 MeV

s

1/2=mN+mη Data: I. Jaegle et al., CBELSA & TAPS

Solid/Black: γp → ηp Dotted/Red: γn → ηn

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

The ratio σn/σp = σ(γn → ηn) σ(γp → ηp)

700 800 900 1000 1100 1200 Eγ [MeV] 0.5 1 1.5 2 σn / σp ηN

s

1/2=1535 MeV

KΛ KΣ Data: I. Jaegle et al., CBELSA & TAPS

◮ Solid line: Present result (incl. Fermi) ◮ Dotted: No γK+Λ ◮ Dash-dotted: from NLO chiral (x20) ◮ Dashed: no Fermi motion ◮ Intermediate states in photon loops,

Q = 0, 1:

◮ π−p, π0n, ηn, K0Λ, K+Σ−, K0Σ0 ◮ π0p, π+n, ηp, K+Λ, K+Σ0, K0Σ+ ◮ Photon excitation of intermediate, SU(3)

allowed states (photon loops) renders σn and σp differently. KΣ threshold enhancement in σn.

◮ Peak in σn/σp: Direkt consequence of

Weinberg-Tomozawa driving term from LO χ Lagrangian.

◮

Further tests of the model München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

The ratio σn/σp = σ(γn → ηn) σ(γp → ηp)

700 800 900 1000 1100 1200 Eγ [MeV] 0.5 1 1.5 2 σn / σp ηN

s

1/2=1535 MeV

KΛ KΣ Data: I. Jaegle et al., CBELSA & TAPS

◮ Solid line: Present result (incl. Fermi) ◮ Dotted: No γK+Λ ◮ Dash-dotted: from NLO chiral (x20) ◮ Dashed: no Fermi motion ◮ Intermediate states in photon loops,

Q = 0, 1:

◮ π−p, π0n, ηn, K0Λ, K+Σ−, K0Σ0 ◮ π0p, π+n, ηp, K+Λ, K+Σ0, K0Σ+ ◮ Photon excitation of intermediate, SU(3)

allowed states (photon loops) renders σn and σp differently. KΣ threshold enhancement in σn.

◮ Peak in σn/σp: Direkt consequence of

Weinberg-Tomozawa driving term from LO χ Lagrangian.

◮

Further tests of the model München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

The ratio σn/σp = σ(γn → ηn) σ(γp → ηp)

700 800 900 1000 1100 1200 Eγ [MeV] 0.5 1 1.5 2 σn / σp ηN

s

1/2=1535 MeV

KΛ KΣ Data: I. Jaegle et al., CBELSA & TAPS

◮ Solid line: Present result (incl. Fermi) ◮ Dotted: No γK+Λ ◮ Dash-dotted: from NLO chiral (x20) ◮ Dashed: no Fermi motion ◮ Intermediate states in photon loops,

Q = 0, 1:

◮ π−p, π0n, ηn, K0Λ, K+Σ−, K0Σ0 ◮ π0p, π+n, ηp, K+Λ, K+Σ0, K0Σ+ ◮ Photon excitation of intermediate, SU(3)

allowed states (photon loops) renders σn and σp differently. KΣ threshold enhancement in σn.

◮ Peak in σn/σp: Direkt consequence of

Weinberg-Tomozawa driving term from LO χ Lagrangian.

◮

Further tests of the model München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

The ratio σn/σp = σ(γn → ηn) σ(γp → ηp)

700 800 900 1000 1100 1200 Eγ [MeV] 0.5 1 1.5 2 σn / σp ηN

s

1/2=1535 MeV

KΛ KΣ 20x Data: I. Jaegle et al., CBELSA & TAPS

◮ Solid line: Present result (incl. Fermi) ◮ Dotted: No γK+Λ ◮ Dash-dotted: from NLO chiral (x20) ◮ Dashed: no Fermi motion ◮ Intermediate states in photon loops,

Q = 0, 1:

◮ π−p, π0n, ηn, K0Λ, K+Σ−, K0Σ0 ◮ π0p, π+n, ηp, K+Λ, K+Σ0, K0Σ+ ◮ Photon excitation of intermediate, SU(3)

allowed states (photon loops) renders σn and σp differently. KΣ threshold enhancement in σn.

◮ Peak in σn/σp: Direkt consequence of

Weinberg-Tomozawa driving term from LO χ Lagrangian.

◮

Further tests of the model München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

The ratio σn/σp = σ(γn → ηn) σ(γp → ηp)

700 800 900 1000 1100 1200 Eγ [MeV] 0.5 1 1.5 2 σn / σp ηN

s

1/2=1535 MeV

KΛ KΣ Data: I. Jaegle et al., CBELSA & TAPS

◮ Solid line: Present result (incl. Fermi) ◮ Dotted: No γK+Λ ◮ Dash-dotted: from NLO chiral (x20) ◮ Dashed: no Fermi motion ◮ Intermediate states in photon loops,

Q = 0, 1:

◮ π−p, π0n, ηn, K0Λ, K+Σ−, K0Σ0 ◮ π0p, π+n, ηp, K+Λ, K+Σ0, K0Σ+ ◮ Photon excitation of intermediate, SU(3)

allowed states (photon loops) renders σn and σp differently. KΣ threshold enhancement in σn.

◮ Peak in σn/σp: Direkt consequence of

Weinberg-Tomozawa driving term from LO χ Lagrangian.

◮

Further tests of the model München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

Prediction σn/σp (N reconstructed)

• M. D., K. Nakayama, PLB 683 (2010)

Combining curve from PLB 683 with recent data.

1600 1800 2000 2200 E [MeV] 0.5 1 1.5 2 2.5 σn / σp

Data: I. Jaegle et al., submitted to EPJA ◮ Neutron in final state reconstructed

→ Elimination of Fermi motion

◮ Prediction (at least) as narrow as new

CBELSA/TAPS data.

◮ Overall different scale in individual σn,

σp data compared to previous measurement → Compare ratio.

◮ Nuclear effects neglected (supported

by experiment).

◮

Analogy: Cusp in γp → π0p München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

Distinguishing cusps from resonances on the lattice [ex.: a0(980)]

• M. D., U.-G. Meißner, E. Oset, A. Rusetsky, in preparation

Hadronic model: Oller/Oset, NPA (1997)

2 2.5 3 3.5 L [mπ

• 1]

600 800 1000 1200 E [MeV] 940 960 980 1000 E [MeV] 1 2 3 4 5 6 7 |t22|

2 I=1 / 10 3

2 2.5 3 L [mπ

• 1]

900 950 1000 1050 1 2 3 4 qmax = 904 MeV 904 MeV qmax = 1094 Mev 630 MeV 1094 MeV 904 MeV qmax = 630 MeV ◮ Cusp vs. resonance: Different signals in lattice levels E(L)

[Lüscher formalism in coupled channels].

◮ Twisted boundary conditions shift thresholds but not resonances

→ may be suited to distinguish resonances from cusps

[enhanced signal (dashed lines)].

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

Prediction for the reaction γn → K0Λ

Free K+Λ production on p:

1600 1700 s

1/2 [MeV]

1 2 3 σ [µb] γ p --> K

+ Λ

Dash-dotted line: KAON-Maid, S-wave only Data: Saphir

◮ Much larger uncertainties from ππN

channel than in case of η. Quasifree KΛ production on p and n:

900 1000 1100 1200 Eγ [MeV] 1 2 3 4 5 σ [µb] 900 1050

0.5 1 1.5 2 2.5

σn / σp

• w. ππN

γ p --> K+Λ

KΣ no enhancement

γ n --> K0Λ

KΛ

◮ Pentaquark coupling to γn and KΛ

→ Peak in σn/σp expected like for η.

◮ No peak (rather dip) predicted in

present approach.

◮ Can serve to distinguish between

both explanations.

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction Coupled channels dynamics Combined Analysis

Conclusions

◮ Global fit (18 parms.) of 11 photoproduction and 8 hadronic, independent reaction

data sets, spanning 700 MeV in energy and involving πN, ηN, KΛ, KΣ final states.

◮ γn → ηn: Intermediate KΛ, KΣ loops + photon coupling leads to KΣ threshold

enhancement (peak in σn/σp).

◮ Consequence of underlying hadron dynamics: Weinberg-Tomozawa term from

chiral Lagrangian induces strong channel coupling through its SU(3) structure.

◮ New data (not yet considered) from CBELSA/TAPS, GRAAL, · · · :

◮ Polarization in γp → ηp [Kuznetsov/Polyakov, JETP Lett. (2008)], ◮ Compton scattering [Kuznetsov/Polyakov et al., arXiv 1003.4585 (2008)], ◮ Fermi-defolded, angular binned data [A2/MAMI, PRC82 (2010)]. ◮ γn → K0Λ, · · · [Jaegle et al., under analysis], planned with higher statistics at MAMI-C. München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

The ∆∗(1700) and its π∆, η∆, KΣ∗ decays

M.D., E. Oset, D. Strottman, PRC 73 (2006), PLB 639 (2006)

◮ 0− meson octet ⊗ 3/2+ baryon decuplet −

→ 3/2− resonances

M.F .M Lutz et al., PLB 585 (2004)

• S. Sarkar et al., NPA 750 (2005)

◮ Unitarized coupled channel interaction ∆(1232) π ∆(1232) η Σ∗(1385) K

Couplings ∆π ∆η Σ∗K |ggenerated|2(**) 1 4.8 11.56 g2

SU(3)(*,**)

1 1/5 2/5 Ratio 1 24 29

(*) assuming ∆∗(1700) belongs to a decuplet (see PDB) (**) rescaled to ∆π coupling

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

The π0ηp final state

◮ De-excitation modes into π0ηp final state: γN → X* N*(1535)

• p
• (1232)

◮ ∆∗(1700)∆(1232)η

coupling provided by model for dynamically generated ∆∗(1700).

◮ “Tree level” contribution:

p γ

∆∗ ∆

η π0 p

◮ γp → π0ηp and γp → K0π0Σ+ measured at many experimental facilities

(ELSA, GRAAL, MAMI, LNS).

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

Diagrammatic expansion of γp → π0ηp

Adding a π0 to the γN → ηN amplitude is not enough... p γ

∆∗ ∆

η π0 p π0 π0 π0 π0 π0 π0 η p η p η p η p η p η p M B ∆∗ X∗ B m m X∗ B (a) (b) (c) (d) (e) (f)

∆∗∆η, ∆∗Σ∗K, ∆∗∆π München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

Diagrammatic expansion of γp → π0ηp

Adding a π0 to the γN → ηN amplitude is not enough... p γ

∆∗ ∆

η π0 p π0 π0 π0 π0 π0 π0 η p η p η p η p η p η p M B ∆∗ X∗ B m m X∗ B (a) (b) (c) (d) (e) (f)

∆∗∆η, ∆∗Σ∗K, ∆∗∆π München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

Cross section

1200 1400 1600 Eγ [MeV] 1 2 3 4 5 6 7 σ [µ b] 1700 1800 1900 2000 s

1/2 [MeV]

• I. Horn, Ph.D. (CB-ELSA)

Ajaka et al., PRL 100 (Graal)

γ p --> π

0 η p

Solid line: Full model for the N∗(1535) from M.D., E. Oset, D. Strottman, PRC 73 (2006). Gray Band: Update from M.D., E. Oset, D. Strottman, PLB 639 (2006). (realistic ∆∗(1700) width, exp. error from A1/2 A3/2 for γp∆∗(1700) coupling).

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

Invariant mass distributions

from Ajaka et al., PRL100 (2008) [GRAAL]

◮ open circles: Data from PRL

100 (2008).

◮ thick solid lines: Present model ◮ thin solid line: phase space ◮ dashed line: pure η ∆ final

state

◮ dotted lines: pure π0 S11 final

state

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

Beam asymmetry

from Ajaka et al., PRL100 (2008)

◮ solid circles: Data from PRL

100 (2008).

◮ Solid lines; Present model. ◮ Test: Remove ∆∗(1700)∆η

coupling → even sign changes!

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

The polarization observables IS and IC

• M. D., E. Oset, Ulf-G. Meißner, EPJA 46 (2010).

First measurement of IS, IC (fixed φ∗) dσ dφ = σ0[1 + IS sin(2φ) + IC cos(2φ)] by CBELSA/TAPS E. Gutz et al., Phys.Lett.B 687,11,2010

◮ Monte-Carlo evaluation of the

binned double differential cross section d2σ(φ, φ∗) dφ dφ∗ ≃ ∆2σ(φi, φ∗

k )

∆φ ∆φ∗

◮ Prediction of IS, IC (and other

• bservables) using the 2006

model [M.D., E. Oset, D. Strottman, PLB 639

(2006)] München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

Predictions for IC DATA: CBELSA/TAPS, E. Gutz et al., Phys.Lett.B 687,11,2010

• 0.5

0.5 I

C p

• 0.5

0.5 I

C π

π/2 π 3π/2 φ

* [rad]

• 0.5

0.5 I

C η

π/2 π 3π/2 φ

* [rad]

π/2 π 3π/2 φ

* [rad]

W=1706 MeV W=1834 MeV W=1946 MeV

Red solid lines: Predicted results. Black dotted lines: Without the ∆(1700)η∆ and ∆(1700)KΣ(1385) couplings predicted from the chiral unitary model.

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

Predictions for IS DATA: CBELSA/TAPS, E. Gutz et al., Phys.Lett.B 687,11,2010

• 0.5

0.5 I

S p

• 0.5

0.5 I

S π

π/2 π 3π/2 φ

* [rad]

• 0.5

0.5 I

S η

π/2 π 3π/2 φ

* [rad]

π/2 π 3π/2 φ

* [rad]

W=1706 MeV W=1834 MeV W=1946 MeV

Red solid lines: Predicted results. Black dotted lines: Without the ∆(1700)η∆ and ∆(1700)KΣ(1385) couplings predicted from the chiral unitary model.

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

γ induced strangeness production

M.D., E. Oset, D. Strottman, PLB 639

p γ

∆∗ Σ∗+

K0 π0 Σ+

π0 π0 π0 π0 π0 π0 K0 Σ+ K0 Σ+ K0 Σ+ K0 Σ+ K0 Σ+ K0 Σ+ M B ∆∗ X∗ B m m X∗ (M, B) = (πN), (KΣ), (KΛ) (m, X∗, B) = (π∆N), (η∆N), (KΣ∗Σ), (KΣ∗Λ) B

K+ π± Λ, Σ−

◮ Data: Saphir

• Rad. decay,...

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

γ induced strangeness production

M.D., E. Oset, D. Strottman, PLB 639

p γ

∆∗ Σ∗+

K0 π0 Σ+

π0 π0 π0 π0 π0 π0 K0 Σ+ K0 Σ+ K0 Σ+ K0 Σ+ K0 Σ+ K0 Σ+ M B ∆∗ X∗ B m m X∗ (M, B) = (πN), (KΣ), (KΛ) (m, X∗, B) = (π∆N), (η∆N), (KΣ∗Σ), (KΣ∗Λ) B

K+ π± Λ, Σ−

1400 1500 1600 1700 Eγ [MeV] 0.05 0.1 0.15 0.2 0.25 σ [µ b] 1900 2000 s

1/2 [MeV]

γ p --> π

0 K 0 Σ + Data: M. Nanova et al., EPJA 35 (2008)

• 1
• 0.5

0.5 1

cos (θΣ

c.m. ) 0.005 0.01 0.015 0.02

dσ / d Ω [µb /sr]

γ p --> π

0 K 0 Σ +

◮ Data: Saphir

• Rad. decay,...

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

γ induced strangeness production

M.D., E. Oset, D. Strottman, PLB 639

p γ

∆∗ Σ∗+

K0 π0 Σ+

π0 π0 π0 π0 π0 π0 K0 Σ+ K0 Σ+ K0 Σ+ K0 Σ+ K0 Σ+ K0 Σ+ M B ∆∗ X∗ B m m X∗ (M, B) = (πN), (KΣ), (KΛ) (m, X∗, B) = (π∆N), (η∆N), (KΣ∗Σ), (KΣ∗Λ) B

K+ π± Λ, Σ−

1400 1500 1600 1700 Eγ [MeV] 0.05 0.1 0.15 0.2 0.25 σ [µ b] 1900 2000 s

1/2 [MeV]

γ p --> π

0 K 0 Σ + Data: M. Nanova et al., EPJA 35 (2008)

• 1
• 0.5

0.5 1

cos (θΣ

c.m. ) 0.005 0.01 0.015 0.02

dσ / d Ω [µb /sr]

γ p --> π

0 K 0 Σ +

◮ Data: Saphir

• Rad. decay,...

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

γ induced strangeness production

M.D., E. Oset, D. Strottman, PLB 639

p γ

∆∗ Σ∗+

K0 π0 Σ+

π0 π0 π0 π0 π0 π0 K0 Σ+ K0 Σ+ K0 Σ+ K0 Σ+ K0 Σ+ K0 Σ+ M B ∆∗ X∗ B m m X∗ (M, B) = (πN), (KΣ), (KΛ) (m, X∗, B) = (π∆N), (η∆N), (KΣ∗Σ), (KΣ∗Λ) B

K+ π± Λ, Σ−

1400 1500 1600 1700 Eγ [MeV] 0.05 0.1 0.15 0.2 0.25 σ [µ b] 1900 2000 s

1/2 [MeV]

γ p --> π

0 K 0 Σ + Data: M. Nanova et al., EPJA 35 (2008)

• 1
• 0.5

0.5 1

cos (θΣ

c.m. ) 0.005 0.01 0.015 0.02

dσ / d Ω [µb /sr]

γ p --> π

0 K 0 Σ +

0.5 1 1.5 2 1800 1900 2000 2100 s

1/2 [MeV]

0.2 0.4 0.6

σ [µ b]

Λ(1405) Σ

+ --> nπ +

Σ

+ --> pπ

1250 1500 1750 2000 Eγ [MeV] 0.1 0.2 0.3

Λ(1405)

γ p --> K

0 π + Λ

γ p --> K

+ π

• Σ

+

γ p --> K

+ π + Σ

• F.W. Wieland, Ph.D. Thesis

Aachen Coll., PR188, N. Cim. 49A Cambridge Bubble Chamber Group, PR156

• I. Schulday, Ph.D. Thesis

Large error bars: ◮ Data: Saphir

• Rad. decay,...

München, 17.06.2011 η and π0η photoproduction...

η photoproduction on proton and neutron π0η photoproduction 0− meson octet ⊗ 3/2+ baryon decuplet Results

Conclusions (π0η photoproduction)

◮ χ unitary predictions for ∆∗(1700) → ∆η, Σ∗K, γN, · · · can be tested in

recent experiments at ELSA/MAMI/GRAAL.

◮ IS and IC (and other observables) have been predicted;

experimental support for strong η∆ channel in S-wave.

◮ New data (not yet considered):

circular beam asymmetry (MAMI, [PLB693, 2010]), · · · .

München, 17.06.2011 η and π0η photoproduction...

The loop function G

back

◮ Imaginary part opens at threshold. ◮ Real, dispersive part shows pronounced structure at threshold.

München, 17.06.2011 η and π0η photoproduction...

Resonance content of the photoproduction amplitude

back

Analytic continuation of Feynman parameterized loops

◮ Analytic continuation of

hadronic part MB → ηN trivial.

◮ Photon loop ˜

dj:

(a) (b)

◮ ˜

d(2)

j

= ˜ dj + 2δ˜ dj

Feynman integral → contour integral Pole approximation γn → ηn

1500 1600 1700 1800 5 5 10 z MeV Re E0 mΠ 1 1500 1600 1700 1800 5 10 15 z MeV Im E0 mΠ 1

→ not saturated by resonances.

München, 17.06.2011 η and π0η photoproduction...

Additional degrees of freedom

back

• M. D., K. Nakayama, EPJA 43 (2010)

◮ The N∗(1650): Closeby resonance with the N∗(1535)’s quantum

numbers → interfering resonances

◮ Could the N∗(1535) be genuine? → put it as a resonance! ◮ → Include two genuine pole terms δVij ∼ gi gj (√s−M) in the potential;

supply γN → N∗ bare couplings.

→ Check dependence of the results on these ingredients

◮ Almost no freedom to tune photoproduction on neutron and proton

independently.

◮ Difference to SAID, MAID η photoproduction analyses, ...: only S-wave;

but: includes KY coupled channels and dispersive parts of loop integral (not K-matrix; not an isobar analysis).

◮ Fit appropriate “data” (partial waves, multipoles) on pion- and

photon-induced reactions (Global fit).

München, 17.06.2011 η and π0η photoproduction...

Photoproduction

γN → πN, γN → KΛ, γN → KΣ

back 1200 1400 1600

• 5

5 10 15 20 Re E0+ [mfm] 1200 1400 1600

• 20
• 15
• 10
• 5

5 1200 1400 1600

• 40
• 30
• 20
• 10

1200 1400 1600 s

1/2 [MeV]

2 4 6 8 10 Im E0+ [mfm] 1200 1400 1600 s

1/2 [MeV]

• 6
• 4
• 2

2 1200 1400 1600 s

1/2 [MeV]

• 5

5 10

S11 (p) S11 (n) S31

"data": Said 1 2 3 4 5 σ [µb] 2 4 σ [µb] 1600 1700 1800 s

1/2 [MeV]

2 4 σ [µb] γ p --> K

+ Λ

γ p --> K

+ Σ

γ p --> K

0 Σ +

München, 17.06.2011 η and π0η photoproduction...

Tests of η photoproduction

Add/Remove ingredients (no refit)

back

Previous calculations/ UχPT framework:

700 750 800 850 900 Eγ [Mev] 0.5 1 1.5 σn/σp

from Jido, Oset, M.D.

• A. Fix

Maid 3 Kaiser, Weise et al. Weiss, Heijny, Krusche, Schadmand et al. (1999-2003)

700 800 900 1000 1100 Eγ [MeV] 0.5 1 1.5

Left: Low energy region; left shoulder of σn/σp peak. Right: [Jido, Oset, M.D., PRC 77 (2008)] with Fermi motion (dashed). → (Shoulder of the) peak in σn/σp is present in previous calculations in UχPT coupled channel framework; there: no N∗(1650), no ηN data in the fit. Baryon pole term and ππN channel:

800 1000 1200 Eγ [MeV] 5 10 15 20 σ [µb] 800 1000 Eγ [MeV] 0.5 1 1.5 2 σn/σp

20x

◮ Solid: Present result. ◮ Dashed: incl. higher order baryon

terms.

◮ Dashed dotted: incl. ππN. ◮ Dotted: No genuine resonance

states [N∗(1650)+BG].

◮ Orange dashed: only WT term

(scaled by x20; no Fermi)

München, 17.06.2011 η and π0η photoproduction...

Analytic structure

back München, 17.06.2011 η and π0η photoproduction...

The ∆∗(1700) in πN scattering

back

M.D., NPA 786 (2007)

1200 1400 1600 1800 2000 s

1/2 [MeV]

• 0.2
• 0.1

0.1 0.2 0.3 D33 Re D33 Im D33 Fit 1 Fit 2 1200 1400 1600 1800 2000 s

1/2 [MeV]

• 0.1

0.1 0.2 D33 Re D33 Im D33 Fit 3 Fit 3’

Coupled channels ∆(1232)π, ∆(1232)η, Σ∗(1385)π Novelty: Inclusion of (Nπ)d

München, 17.06.2011 η and π0η photoproduction...

Prediction for the radiative decay

back

M.D., NPA 786 (2007)

proton γ (k) ∆0 (q-p) (p-k) ∆ π π+ (p) (1) q

• p

γ ∆0 π+ ∆ π (2)

γ (k) proton (p-k) π0 (q-p) ∆+ (p) ∆ π

(3) q

• p

γ ∆++ ∆ π π− (4) p γ ∆++ π− ∆ π (5)

γ p π− ∆++ ∆ π

(6) p γ Σ∗0 ∆ π K+ (7) p γ Σ∗0 K+ ∆ π (8)

γ p K0 Σ∗+ ∆ π

(9) p γ n ∆ π π+ (10)

Mechanisms for the ∆∗(1700) decay in s- and d-wave loops. The shaded circles represent the ∆∗(1700). Γγ = 602 ± 140 keV vs. Γγ = 570 ± 254 keV from experiment

München, 17.06.2011 η and π0η photoproduction...

Prediction for the radiative decay

back

M.D., NPA 786 (2007)

proton γ (k) ∆0 (q-p) (p-k) ∆ π π+ (p) (1) q

• p

γ ∆0 π+ ∆ π (2)

γ (k) proton (p-k) π0 (q-p) ∆+ (p) ∆ π

(3) q

• p

γ ∆++ ∆ π π− (4) p γ ∆++ π− ∆ π (5)

γ p π− ∆++ ∆ π

(6) p γ Σ∗0 ∆ π K+ (7) p γ Σ∗0 K+ ∆ π (8)

γ p K0 Σ∗+ ∆ π

(9) p γ n ∆ π π+ (10)

Mechanisms for the ∆∗(1700) decay in s- and d-wave loops. The shaded circles represent the ∆∗(1700). Γγ = 602 ± 140 keV vs. Γγ = 570 ± 254 keV from experiment

München, 17.06.2011 η and π0η photoproduction...

Analogy: Cusp in γp → π0p

back

M.D., K. Nakayama, EPJA 43 (2010)

145 150 155 160 Eγ [MeV]

• 1
• 0.5

0.5 1 E0+ (π

0p) (10 3 / mπ

+) PRL 87, 232501 (2001) TAPS/MAMI PRC 55, 2016 (1997) [Im: gray band] PRC 53, R1052 (1996) Maid 2007 [EPJA 34,69] ChPT [ZPhys C70, 483 (1996)] DR [PLB 399,13] present model

γ p --> π

0 p

present model: Re E0+ shitfted by -0.59

π

+n

corresponds to 10 % change in Re phototransi. loop

(shifted) München, 17.06.2011 η and π0η photoproduction...

München, 17.06.2011 η and π0η photoproduction...