Assoiated production. Hyperon photoproduction Lambda polarization normal to production plane (parity!!) weak decay:

Assoiated production

Hyperon photoproduction

Lambda polarization

●normal to production plane (parity!!)●weak decay:

Sigma polarization

Hyperon polarization in photoproduction



Michael Ostrick, Universität Bonn

pseudoscalar mesons γ p → p π0 , γ p→ p η

strangeness γ p→ K Λ, γ p→ K Σ

Selected results:

Photoexcitation of N*/∆*-resonances

Extraction of resonance parameters


amplitude analyses → resonance parameters

● single-channel isobar models (e.g. MAID)

● multi-channel approaches SAID, Giessen-coupled-channel-model

dynamical models → relation of N* parameters to quark-models, lattice QCD

Bonn-Gatchina (A. Sarantsev et al. hep-ph/0407211)•isobar analysis (Breit-Wigner/K-matrix)•u- and t-channel•relativistically invariant•analyticity/(unitarity)


N*/∆* resonances in PWA

N* ∆*

selected results: π0 and η photoproduction


ELSA


PRL 94(2005)012004

γ p → p π0

Δ(1232)


PRL 94(2005)012004

γ p → p π0

Data in PWA:

Crystal-Barrel π0 & η

TAPS/MAMI π0 & η (low energy)

GRAAL π0 & η lin. polarization

Bonn γp → nπ+

(isospin !)

Δ(1232)


PRL 94(2005)012004

S11(1535)D13(1520)2-3% P11(1440)

D33(1700)F15(1680)S11(1650) F37(1950)

P33(1920)

γ p → p π0

Δ(1232)


PRL 94(2005)012004

Δ(1232)

S11(1535)D13(1520)2-3% P11(1440)

D33(1700)F15(1680)S11(1650) F37(1950)

P33(1920)

γ p → p π0


PRL 94(2005)012003

γ p → p η

MAMI

GRAAL

CLAS

CB-ELSA

PWA

S11

(1535)


PRL 94(2005)012003

γ p → p η

MAMI

GRAAL

CLAS

CB-ELSA

PWA

S11

(1535)


PRL 94(2005)012003

γ p → p η: PWA

P13

(1720)

S11

(1535)


PRL 94(2005)012003

γ p → p η: PWA

P13

(1720)

S11

(1535)

No 3rd S11

needed


PRL 94(2005)012003

γ p → p η: PWA

P13

(1720)

proposed "new"

D15

(2070)

m = 2068 ± 22 MeVΓ = 295 ± 40 MeV

S11

(1535)


PRL 94(2005)012003

γ p → p η: PWA

P13

(1720)

proposed "new"

D15

(2070)

m = 2068 ± 22 MeVΓ = 295 ± 40 MeV

5/2-

1/2-

1/2+

S11

(1535)


PRL 94(2005)012003

γ p → p η: PWA

P13

(1720)

proposed "new"

D15

(2070)

m = 2068 ± 22 MeVΓ = 295 ± 40 MeV

5/2-

1/2-

1/2+

S11

(1535)

(double) polarization

observables !


γ p → p η: double polarization

long. pol. target, circ. pol γ : helicity 1/2 - 3/2

long. pol. target, lin. pol γ :

5/2-

1/2-

1/2+


strangeness production

p p

p p X

SAPHIR: EPJ A 19, 251 (2004) EPJ A 24, 275 (2005)

γ p → K+ Λγ p → K+ Σ0

γ p → K0 Σ+



γ p → K+ Λ

energy dependent discrepancy up to 20% between SAPHIR and CLAS



γ p → K+ Λ

energy dependent discrepancy up to 20% between SAPHIR and CLAS

PWA fit with the same N*/∆* states as in π0 and η production is possible (hep-ex/0506011)


strangeness production: γ p → K+ Λ

Linear rise -> s,p wave interference!



S11

(1650)

P13

(1720)

P11

(1710)?

new P11

(1840)?

Linear rise -> s,p wave interference!



D13

(1895) ?

(P11

(1900) ?3rd S

11 (1900) ?)

S11

(1650)

P13

(1720)

P11

(1710)?

new P11

(1840)?



D13

(1895) ?

(P11

(1900) ?3rd S

11 (1900) ?)

S11

(1650)

P13

(1720)

P11

(1710)?

new P11

(1840)?


strangeness production: γ p → K Σ

∆(1700)D33

∆(1940)D33

N(1840)P11

γ p → K+ Σ0 γ p → K0 Σ+

Main resonance contributions:


strangeness production: γ p → K Σ

∆(1700)D33

∆(1940)D33

N(1840)P11

γ p → K+ Σ0 γ p → K0 Σ+

Main resonance contributions:

(double) polarization

and

electroproduction!


photoexcitation of N*/∆* resonances

N* ∆*

Documents

Assoiated production. Hyperon photoproduction Lambda polarization normal to production plane (parity!!) weak decay: