[PPT] - Photoproduction of p , K 0 + , and p using p p + 0 Data PowerPoint Presentation

SLIDE 1

Introduction Experimental Results Summary and Outlook

Photoproduction of p η, K 0 Σ+, and p ω using CLAS-g12 γp → p π+π−π0 Data

Volker Credé

Florida State University, Tallahassee, FL ∗

CLAS Collaboration Meeting Jefferson Lab 11/15/2019

∗

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 2

Introduction Experimental Results Summary and Outlook

Outline

1

Introduction Spectroscopy of Nucleon Resonances

2

Experimental Results The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

3

Summary and Outlook

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 3

Introduction Experimental Results Summary and Outlook Spectroscopy of Nucleon Resonances

Outline

1

Introduction Spectroscopy of Nucleon Resonances

2

Experimental Results The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

3

Summary and Outlook

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 4

Introduction Experimental Results Summary and Outlook Spectroscopy of Nucleon Resonances

CLAS (6 GeV) at JLab 1998 - 2012

Photo-/electroproduction experiments in search for N∗ states and measurement

f the transition amplitudes.

A

B

C

D

Double-Polarization Experiments

➜ CLAS FROST

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 5

Introduction Experimental Results Summary and Outlook Spectroscopy of Nucleon Resonances

Table representing CLAS@JLab measurements

σ Σ T P E F G H Tx′ Tz′ Lx′ Lz′ Ox′ Oz′ Cx′ Cz′ Proton targets p π0

()
n π+
()
p η
()
p η′
()
p ω (φ)
()
Tensor polarization, SDMEs

K + Λ

K + Σ0
K 0 Σ+
Neutron (deuteron) targets

p π−

K + Σ−
K 0 Λ
∗
K 0 Σ0
∗
Complete Experiments?

“Uncertainty is an uncomfortable position. But Certainty is an absurd one.” Voltaire

∗ published

published
acquired or under analysis
V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 6

Introduction Experimental Results Summary and Outlook Spectroscopy of Nucleon Resonances

Table representing CLAS@JLab measurements

σ

Σ T P E F G H Tx′ Tz′ Lx′ Lz′ Ox′ Oz′ Cx′ Cz′ Proton targets p π0

()
n π+
()
p η
()
p η′
()
p ω (φ)
()
Tensor polarization, SDMEs

K + Λ

K + Σ0
K 0 Σ+
Neutron (deuteron) targets

p π−

K + Σ−
K 0 Λ
∗
K 0 Σ0
∗
Complete Experiments?

“Uncertainty is an uncomfortable position. But Certainty is an absurd one.” Voltaire

∗ published

published
acquired or under analysis
V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 7

Introduction Experimental Results Summary and Outlook Spectroscopy of Nucleon Resonances

Table representing CLAS@JLab measurements

σ Σ T P E F G H Tx′ Tz′ Lx′ Lz′ Ox′ Oz′ Cx′ Cz′ Proton targets p π0

()
n π+
()
p η
()
p η′
()
p ω (φ)
()
Tensor polarization, SDMEs

K + Λ

K + Σ0
K 0 Σ+
Neutron (deuteron) targets

p π−

K + Σ−
K 0 Λ
∗
K 0 Σ0
∗
In addition, two-meson reactions are being analyzed:

γp → (p ρ) → p π+π− (CLAS), γp → p π0π0, p π0η, p π0ω (ELSA, MAMI, etc.)

∗ published

published
acquired or under analysis
V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 8

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Outline

1

Introduction Spectroscopy of Nucleon Resonances

2

Experimental Results The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

3

Summary and Outlook

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 9

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

1/2+

3/2+ 5/2+ 7/2+ 9/2+ 11/2+ 13/2+ 1/2- 3/2- 5/2- 7/2- 9/2- 11/2- 13/2- J

Mass [MeV] 1000 1500 2000 2500 3000

**** **** * **** ** **** ** ** **** ** **** **** * **** *** ** **** ** **** **** *** S S S ***

Spectrum of N∗ Resonances

V. C. & W. Roberts, Rep. Prog. Phys. 76 (2013)

Theory Experiment

2. Excitation Band:

(56, 0+

2 ), (56, 2+ 2 ) ✓

(70, 0+

2 ), (70, 2+ 2 ) (✓)

(20, 1+

2 ) ?

1. Excitation Band:

(70, 1−

1 ) ✓

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 10

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Polarization Transfer in γp → K + Λ : C x & C z

without N(1900)P13 with N(1900)P13

R. Bradford et al. [CLAS Collaboration], PRC 75, 035205 (2007)

Fits: BoGa-Model, V. A. Nikonov et al., Phys. Lett. B 662, 245 (2008)

∗ ∗ N(1900)P13, N(2000)F15, N(1990)F17 Quartet of (70, 2+

2 ) with S = 3 2

➜ No (point-like) quark-diquark oscillations!

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 11

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Polarization Observables in γp → K + Λ (g8b)

1.7 1.8 1.9 2 2.1 2.2 1 − 0.5 − 0.5 1

< -0.55

K

θ

0.75 < cos

1.7 1.8 1.9 2 2.1 2.2 1 − 0.5 − 0.5 1

< 0.25

K

θ 0.05 < cos

1.7 1.8 1.9 2 2.1 2.2 1 0.5 0.5 1

< -0.35

K

θ

0.55 < cos

1.7 1.8 1.9 2 2.1 2.2 1 − 0.5 0.5 1

< 0.45

K

θ 0.25 < cos

1.7 1.8 1.9 2 2.1 2.2 1 0.5 0.5 1

< -0.15

K

θ

0.35 < cos

1.7 1.8 1.9 2 2.1 2.2 1 − 0.5 0.5 1

< 0.65

K

θ 0.45 < cos

1.7 1.8 1.9 2 2.1 2.2 1 0.5 0.5 1

< 0.05

K

θ

0.15 < cos

1.7 1.8 1.9 2 2.1 2.2 1 0.5 0.5 1

< 0.85

K

θ 0.65 < cos

Σ Beam Asymmetry,

W (GeV)

1.7 1.8 1.9 2 2.1 2.2 1 − 0.5 − 0.5 1

< -0.55

K

θ

0.75 < cos

1.7 1.8 1.9 2 2.1 2.2 1 − 0.5 − 0.5 1

< 0.25

K

θ 0.05 < cos

1.7 1.8 1.9 2 2.1 2.2 1 0.5 0.5 1

< -0.35

K

θ

0.55 < cos

1.7 1.8 1.9 2 2.1 2.2 1 − 0.5 0.5 1

< 0.45

K

θ 0.25 < cos

1.7 1.8 1.9 2 2.1 2.2 1 0.5 0.5 1

< -0.15

K

θ

0.35 < cos

1.7 1.8 1.9 2 2.1 2.2 1 − 0.5 0.5 1

< 0.65

K

θ 0.45 < cos

1.7 1.8 1.9 2 2.1 2.2 1 0.5 0.5 1

< 0.05

K

θ

0.15 < cos

1.7 1.8 1.9 2 2.1 2.2 1 0.5 0.5 1

< 0.85

K

θ 0.65 < cos

Target, T

W (GeV)

K

θ cos 1 − 0.5 − 0.5 1 W (GeV) 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3

Beam Asymmetry, Σ Target Asymmetry, T xxx W [ GeV ]

C. A. Paterson et al., Phys. Rev. C 93, 065201 (2016)

— ANL-Osaka — BnGa ’14 — BnGa ’14 refit

W [ GeV ]

LEPS CLAS GRAAL

cos θ K

comparison of kinematic coverage

➜ Additional N∗ 3

2 +, N∗ 5 2 + needed

in BnGa refit.

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 12

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

The CLAS-g12 Experiment (for this analysis)

z Vertex [ cm ]

120
100
80
60

Counts 500 1000 1500 z-vertex cut 1

Target position Shifted upstream by 90 cm

2

Tagging range (E e− = 5.715 GeV) Lowest tagged photon energy Eγ ≈ 1150 MeV

3

Trigger

1

2 tracks & Eγ > 3.6 GeV

2

3 tracks & no Eγ restrictions

4

Polarization Circularly-pol. incident photons

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 13

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Preparation of the γp → p π+π−π0 Final State

The reaction γp → p π+π−π0 is interesting for many reasons:

1

γp → p ω → p π+π−π0 Initial motivation: This high-statistics channel is important to understand cross sections using g12 data. Moreover: Measurement of g12 SDMEs (combined with SDMEs from g8b) complements FROST results and extends the earlier g11a results into the Regge regime.

2

Primary motivation: γp → K 0 Σ+ → p π+π−π0 (cross sections; polarization observables P, Cx, Cz)

3

Byproduct but first to be published: γp → p η → p π+π−π0 ➜ Work by the g12 group; FSU students Z. Akbar, T. Hu, F . Gonzalez

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 14

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Preparation of the γp → p π+π−π0 Final State

β ∆

0.1

0.1 Counts 5 10

3

10 ×

= 0.009 σ

β ∆

0.1

0.1 Counts 2 4 6 8

3

10 ×

= 0.011 σ

1 2 3 4

6

10 ×

p [ GeV ]

1 2 3

m

β

0.2 0.4 0.6 0.8 1

±

π proton

Event reconstruction and selection criteria

(CLAS-g12 Run Group, CLAS-NOTE 2017-002, 2017)

Selection of tracks: γp → p π+π− (π0) Standard g12 fiducial cuts, ELoss & momentum corrections z-Vertex cut: −110 cm < z vertex < −72 cm PID: 3σ cuts on ∆β distributions for either proton or π+

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 15

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Preparation of the γp → p π+π−π0 Final State

CL (Monte Carlo) 0.2 0.4 0.6 0.8 1 Counts 10 20 30 40 50 60 70

3

10 × CL (data) 0.2 0.4 0.6 0.8 1 Counts 5 10 15 20 25 30 35 40 45

3

10 × Normalized Slopes

1
0.5

0.5 1 Counts 5 10 15 20 25 30 35 40 45 50

Kinematic fitting and reconstruction of missing π0: Covariance matrix tuned to exclusive γp → p π+π− channel. Normalized slopes: a = a a/2 + b Event selection with p CL > 0.01

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 16

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Preparation of the γp → p π+π−π0 Final State

450 500 550 600 Counts 50 100 150 200 250 < -0.1

c.m. η

θ

0.2 < cos

450 500 550 600 < 0.1

c.m. η

θ 0.0 < cos ]

2

[ MeV/c

π

π

+

π

m 450 500 < 0.8

c.m. η

θ 0.7 < cos

]

2

[ MeV/c

π

π

+

π

M 450 500 550 600 650 Counts 10 20 30 40 50 60

3

10 ×

W ∈ [ 1.9; 1.92 ] GeV

Final background subtraction based on the event-based Q-value method: cos θ η

c.m., cos θ HEL, φ HEL, φ η lab, λ

➜ Total uncertainty: σ2 = σ2

η + σ2 statistical

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 17

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Cross Sections for γp → K 0 Σ+ → p π+π−π0

1.15 < E < 1.20 GeV 1.20 < E < 1.25 GeV 1.25 < E < 1.30 GeV 1.30 < E < 1.35 GeV 1.35 < E < 1.40 GeV

0 8 0 6 0 2 0 2 0 6 0 8

1.40 < E < 1.45 GeV

0 8 0 6 0 2 0 2 0 6 0 8

1.45 < E < 1.50 GeV

0 8 0 6 0 2 0 2 0 6 0 8

1.50 < E < 1.55 GeV

0 8 0 6 0 2 0 2 0 6 0 8

1.55 < E < 1.60 GeV

0 8 0 6 0 2 0 2 0 6 0 8

1.60 < E < 1.65 GeV 1.65 < E < 1.70 GeV 1.70 < E < 1.75 GeV 1.75 < E < 1.80 GeV 1.80 < E < 1.85 GeV 1.85 < E < 1.90 GeV 1.90 < E < 1.95 GeV 1.95 < E < 2.00 GeV 2.00 < E < 2.05 GeV 2.05 < E < 2.10 GeV 2.10 < E < 2.15 GeV

0.05 0.05 0.05 0.05 0.1

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5 1 cm K

θ cos b] µ [ Ω /d σ d

]

2

[ MeV/c

π p

m 1.15 1.2 1.25 1.3

3

10 × Counts 5 10 15 20 25 30

3

10 × ]

2

[ MeV/c

π

π

+ π

M 450 500 550 600 650 Counts 10 20 30 40 50 60

3

10 ×

CLAS-g12 • CB-ELSA • CBELSA/TAPS •

Phys. Lett. B 713, 180 (2012)

New cross section results in 50-MeV-wide Eγ bins for −1.15 < Eγ < 3.0 GeV ➜ Need theory support to understand physics!! Σ+

KS

X

Z. Akbar et al. [CLAS Collaboration], in preparation.

P r e l i m i n a r y

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 18

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Cross Sections for γp → K 0 Σ+ → p π+π−π0

1.15 < E < 1.20 GeV 1.20 < E < 1.25 GeV 1.25 < E < 1.30 GeV 1.30 < E < 1.35 GeV 1.35 < E < 1.40 GeV

0 8 0 6 0 2 0 2 0 6 0 8

1.40 < E < 1.45 GeV

0 8 0 6 0 2 0 2 0 6 0 8

1.45 < E < 1.50 GeV

0 8 0 6 0 2 0 2 0 6 0 8

1.50 < E < 1.55 GeV

0 8 0 6 0 2 0 2 0 6 0 8

1.55 < E < 1.60 GeV

0 8 0 6 0 2 0 2 0 6 0 8

1.60 < E < 1.65 GeV 1.65 < E < 1.70 GeV 1.70 < E < 1.75 GeV 1.75 < E < 1.80 GeV 1.80 < E < 1.85 GeV 1.85 < E < 1.90 GeV 1.90 < E < 1.95 GeV 1.95 < E < 2.00 GeV 2.00 < E < 2.05 GeV 2.05 < E < 2.10 GeV 2.10 < E < 2.15 GeV

0.05 0.05 0.05 0.05 0.1

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5 1 cm K

θ cos b] µ [ Ω /d σ d CLAS-g12 • CB-ELSA • CBELSA/TAPS •

New cross section results in 50-MeV-wide Eγ bins for −1.15 < Eγ < 3.0 GeV

X

Phys. Lett. B 713, 180 (2012)
Z. Akbar et al. [CLAS Collaboration], in preparation.

➜ In preparation: (E), P, C x, C z & T, Σ, P, O x, O z

P r e l i m i n a r y

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 19

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Induced Polarization P in γp → K 0 Σ+ → p π+π−π0

1.15 < E < 1.25 GeV 1.25 < E < 1.35 GeV 1.35 < E < 1.45 GeV 1.45 < E < 1.55 GeV 1.55 < E < 1.65 GeV 1.65 < E < 1.75 GeV 1.75 < E < 1.85 GeV 1.85 < E < 1.95 GeV 1.95 < E < 2.05 GeV 2.05 < E < 2.15 GeV 2.15 < E < 2.25 GeV 2.25 < E < 2.35 GeV 2.35 < E < 2.45 GeV 2.45 < E < 2.55 GeV 2.55 < E < 2.65 GeV 2.65 < E < 2.75 GeV 2.75 < E < 2.85 GeV 2.85 < E < 2.95 GeV 2.95 < E < 3.05 GeV Counting Experiment ML Fit CBELSA/TAPS g8b Analysis

1

1

1

1

1

1

1

1

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5 cm

+

Σ

θ cos P

]

2

[ MeV/c

π p

m 1.15 1.2 1.25 1.3

3

10 × Counts 5 10 15 20 25 30

3

10 ×

g12 • / g12 • g8b • CBELSA/TAPS •

X

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 20

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Cross Sections for γp → K 0 Σ+ → p π+π−π0

0.02 0.04

1

1 1715 0.02 0.04

1

1 1730 0.02 0.04

1

1 1755 0.02 0.04

1

1 1770 0.02 0.04

1

1 1785 0.05

1

1 1795 0.05

1

1 1810 0.05

1

1 1820 0.05

1

1 1835 0.05

1

1 1860 0.05 0.1

1

1 1875 0.05 0.1

1

1 1880 0.05 0.1

1

1 1885 0.05 0.1

1

1 1900 0.05 0.1

1

1 1910 0.05 0.1

1

1 1920 0.05 0.1

1

1 1935 0.05 0.1

1

1 1960 0.05 0.1

1

1 1970 0.05 0.1

1

1 1980 0.025 0.05

1

1 1995 0.025 0.05

1

1 2005 0.025 0.05

1

1 2020 0.025 0.05

1

1 2030 0.025 0.05

1

1 2040

MAMI-A2 • CB-ELSA ◦ CBELSA/TAPS ◦

Data are presented in W bins (picture prepared by V. Nikonov) ➜ Clear discrepancies visible!

X

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 21

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Cross Sections for γp → K 0 Σ+ → p π+π−π0

1.15 < E < 1.20 GeV 1.20 < E < 1.25 GeV 1.25 < E < 1.30 GeV 1.30 < E < 1.35 GeV 1.35 < E < 1.40 GeV 1.40 < E < 1.45 GeV 1.45 < E < 1.50 GeV 1.50 < E < 1.55 GeV 1.55 < E < 1.60 GeV 1.60 < E < 1.65 GeV 1.65 < E < 1.70 GeV 1.70 < E < 1.75 GeV 1.75 < E < 1.80 GeV 1.80 < E < 1.85 GeV 1.85 < E < 1.90 GeV 1.90 < E < 1.95 GeV 1.95 < E < 2.00 GeV 2.00 < E < 2.05 GeV 2.05 < E < 2.10 GeV

0.02 0.04 0.06 0.02 0.04 0.06 0.02 0.04 0.06 0.02 0.04 0.06

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5 c.m.

θ cos b] µ [ Ω /d σ d

]

2

[ MeV/c

π

+ π

m 450 500 550 600 Counts 0.2 0.4 0.6 0.8 1 1.2 1.4

3

10 × ]

2

[ MeV/c

π p

m 1.15 1.2 1.25 1.3

3

10 × Counts 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

3

10 ×

MAMI-A2 (2013) MAMI-A2 (2018) • CLAS-g12 K 0 • CLAS-g12 Σ+ •

MAMI / CLAS discrepancies for 1.35 < Eγ < 1.45 GeV ➜ 1.85 < W < 1.90 GeV

1.55 < Eγ < 1.60 GeV

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 22

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Cross Sections for γp → K 0 Σ+ → p π+π−π0

1.15 < E < 1.20 GeV 1.20 < E < 1.25 GeV 1.25 < E < 1.30 GeV 1.30 < E < 1.35 GeV 1.35 < E < 1.40 GeV 1.40 < E < 1.45 GeV 1.45 < E < 1.50 GeV 1.50 < E < 1.55 GeV 1.55 < E < 1.60 GeV 1.60 < E < 1.65 GeV 1.65 < E < 1.70 GeV 1.70 < E < 1.75 GeV 1.75 < E < 1.80 GeV 1.80 < E < 1.85 GeV 1.85 < E < 1.90 GeV 1.90 < E < 1.95 GeV 1.95 < E < 2.00 GeV 2.00 < E < 2.05 GeV 2.05 < E < 2.10 GeV

0.02 0.04 0.06 0.02 0.04 0.06 0.02 0.04 0.06 0.02 0.04 0.06

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5 c.m.

θ cos b] µ [ Ω /d σ d

1.76 < W < 1.80 GeV 1.80 < W < 1.84 GeV 1.84 < W < 1.88 GeV

0.1 0.2 0.3 0.4 0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

c.m.

θ cos b] µ [ Ω /d σ d

CLAS-g11a (2009) CLAS-g12 • MAMI-A2 CBELSA/TAPS

MAMI / CLAS discrepancies for 1.35 < Eγ < 1.45 GeV ➜ 1.85 < W < 1.90 GeV

γp → pη γp → pη γp → pη

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 23

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Cross Sections for γp → pη → p π+π−π0

1.88 < W < 1.90 GeV 1.90 < W < 1.92 GeV 1.92 < W < 1.94 GeV 1.94 < W < 1.96 GeV 1.96 < W < 1.98 GeV 1.98 < W < 2.00 GeV 2.00 < W < 2.02 GeV 2.02 < W < 2.04 GeV 2.04 < W < 2.06 GeV 2.06 < W < 2.08 GeV 2.08 < W < 2.10 GeV 2.10 < W < 2.12 GeV 0.2 0.2 0.2

1
0.5

1 0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5 c.m.

θ cos b] µ [ Ω /d σ d

CLAS g12 - g11a (normalized)

5

5 Counts 10 20 30 40 50 60

= 1.13 σ = 0.42 x

CLAS-g11a (2009) CLAS-g12 • CBELSA/TAPS (2009)

Normalized difference

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 24

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Cross Sections for γp → pη → p π+π−π0

2.12 < W < 2.14 GeV 2.14 < W < 2.16 GeV 2.16 < W < 2.18 GeV 2.18 < W < 2.20 GeV 2.20 < W < 2.22 GeV 2.22 < W < 2.24 GeV 2.24 < W < 2.26 GeV 2.26 < W < 2.28 GeV 2.28 < W < 2.30 GeV 2.30 < W < 2.32 GeV 2.32 < W < 2.34 GeV 2.34 < W < 2.36 GeV 0.2 0.2 0.2

1
0.5

1 0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5 c.m.

θ cos b] µ [ Ω /d σ d

CLAS g12 / g11a 0.5 1 1.5 Counts 10 20 30 40 50 60 70

= 1.06 x

CLAS-g11a (2009) CLAS-g12 • CBELSA/TAPS (2009)

Unweighted ratio

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 25

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Cross Sections for γp → pη → p π+π−π0

2.36 < W < 2.40 GeV 2.40 < W < 2.44 GeV 2.44 < W < 2.48 GeV 2.48 < W < 2.52 GeV 2.52 < W < 2.56 GeV 2.56 < W < 2.60 GeV 2.60 < W < 2.64 GeV 2.64 < W < 2.68 GeV 2.68 < W < 2.72 GeV 2.72 < W < 2.76 GeV 2.76 < W < 2.80 GeV 2.80 < W < 2.84 GeV 2.84 < W < 2.88 GeV 2.88 < W < 2.92 GeV 2.92 < W < 2.96 GeV 2.96 < W < 3.00 GeV 3.00 < W < 3.04 GeV 3.04 < W < 3.08 GeV 3.08 < W < 3.12 GeV 3.12 < W < 3.16 GeV

0.05 0.1 0.15

2

10

1

10

2

10

1

10

2

10

1

10

1
0.5

1 0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5 c.m.

θ cos b] µ [ Ω /d σ d

CLAS-g11a (2009) CLAS-g12 • CBELSA/TAPS (2009)

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 26

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Cross Sections for the Reaction γp → p η → p π+π−π0

2.36 < W < 2.40 GeV 2.40 < W < 2.44 GeV 2.44 < W < 2.48 GeV 2.48 < W < 2.52 GeV 2.52 < W < 2.56 GeV 2.56 < W < 2.60 GeV 2.60 < W < 2.64 GeV 2.64 < W < 2.68 GeV 2.68 < W < 2.72 GeV 2.72 < W < 2.76 GeV 2.76 < W < 2.80 GeV 2.80 < W < 2.84 GeV 2.84 < W < 2.88 GeV 2.88 < W < 2.92 GeV 2.92 < W < 2.96 GeV 2.96 < W < 3.00 GeV 3.00 < W < 3.04 GeV 3.04 < W < 3.08 GeV 3.08 < W < 3.12 GeV 3.12 < W < 3.16 GeV

0.1 0.2 0.1 0.2 0.1 0.2 0.1 0.2 0.7 0.9 0.7 0.9 0.7 0.9 0.7 0.9 0.5 0.7 0.9 c.m.

θ cos b] µ [ Ω /d σ d

New cross section results in 40-MeV-wide W bins for −2.50 < Eγ < 4.72 GeV, or −2.36 < W < 3.12 GeV — JPAC, J. Nys et al. — η MAID 2018

T. Hu et al. [CLAS Collaboration], paper under review.
V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 27

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Cross Sections for the Reaction γp → p η → p π+π−π0

2.52 < W < 2.56 GeV 2.56 < W < 2.60 GeV 2.60 < W < 2.64 GeV 2.64 < W < 2.68 GeV 2.68 < W < 2.72 GeV 2.72 < W < 2.76 GeV 2.76 < W < 2.80 GeV 2.80 < W < 2.84 GeV 2.84 < W < 2.88 GeV 2.88 < W < 2.92 GeV 2.92 < W < 2.96 GeV 2.96 < W < 3.00 GeV 3.00 < W < 3.04 GeV 3.04 < W < 3.08 GeV 3.08 < W < 3.12 GeV

3

10

2

10

1

10 1

3

10

2

10

1

10 1

3

10

2

10

1

10 1 2 1 1 1 1 1

]

2

t [GeV

]

2

b/GeV µ /dt [ σ d

T. Hu et al. [CLAS Collaboration], paper under review.
V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 28

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

(Complete) Experiments in γ p → p ω

Event-based background subtraction (event-based dilution factors) ➜ γp → p π+π− ✓ γp → p π+π−(π0) ✓ In analogy to pseudoscalar mesons:

d σ d Ω = σ0 { 1 − δ l Σ cos 2φ + Λ x ( −δ l H sin 2φ + δ ⊙ F ) − Λ y ( −T + δ l P cos 2φ) − Λ z ( − δ l G sin 2φ + δ ⊙ E)}

The ω is a vector meson (A. I. Titov and B. Kampfer, Phys. Rev. C 78, 038201 (2008)) 2π W f(Φ, Ψ) = 1 − Σf

Φ cos 2Φ − PγΣf b cos 2Ψ + PγΣf d cos 2(Φ − Ψ)

Σh

b = Σr b = 2ρ1 11 + ρ1 00

− 1

2Σh d = Σr d = ρ1 1 −1

− 1

2Σh Φ = Σr Φ = −ρ0 1 −1

published (+ SDME’s) in progress φ = Ψ ≡ Angle between p ω production plane and the photon polarization plane in the overall CM frame. Φ ≡ Azimuthal angle of normal to the ω decay plane in helicity frame - quantization axis in the direction opposite the recoiling proton in the ω rest frame.

Pol. SDMEs: B. Vernarsky (CMU), PhD dissertation
V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 29

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

The Beam Asymmetry in γ p → p ω (CLAS-g9b)

(degrees)

c.m. ω

Θ 20 40 60 80 100 120 140 160 180 Σ ry

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

= 1150 MeV

γ

E

(degrees)

c.m. ω

Θ 20 40 60 80 100 120 140 160 180 Σ ry

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

= 1550 MeV

γ

E

(degrees)

c.m. ω

Θ 20 40 60 80 100 120 140 160 180 Σ ry

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

= 1950 MeV

γ

E

(degrees) c.m. ω Θ 20 40 60 80 100 120 140 160 180 Σ

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

= 1250 MeV

γ

E

(degrees) c.m. ω Θ 20 40 60 80 100 120 140 160 180 Σ

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

= 1650 MeV

γ

E

(degrees) c.m. ω Θ 20 40 60 80 100 120 140 160 180 Σ

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

= 2050 MeV

γ

E

(degrees) c.m. ω Θ 20 40 60 80 100 120 140 160 180 Σ

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

= 1350 MeV

γ

E

(degrees) c.m. ω Θ 20 40 60 80 100 120 140 160 180 Σ

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

= 1750 MeV

γ

E

(degrees) c.m. Θ 20 40 60 80 100 120 140 160 180 Σ

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

= 1450 MeV

γ

E

(degrees) c.m. Θ 20 40 60 80 100 120 140 160 180 Σ

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

= 1850 MeV

γ

E

0.5

0.5 1

0.5

0.5

1
0.5

0.5 50 100 150 50 100 150 50 100 150 50 100 150

) ° (

ω c.m.

Θ Σ

FROST GRAAL (2015) ELSA (2008) GRAAL (2006) CLAS (2017)

hhhhhhh

P . Roy et al. [CLAS Collaboration], PR C 97, 055202 (2018) , P . Collins et al. PL B 773, 112 (2017)

Σ h = Σ r = 2ρ1

11 + ρ1 00

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 30

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

F Observable in γ p → p ω (CLAS g9b)

1250 [1795] MeV 1550 [1946] MeV 1850 [2085] MeV 2150 [2216] MeV 2450 [2340] MeV 1350 [1847] MeV 1650 [1993] MeV 1950 [2130] MeV 2250 [2258] MeV 2550 [2379] MeV 1450 [1897] MeV 1750 [2040] MeV 2050 [2173] MeV 2350 [2299] MeV 2650 [2418] MeV

1
0.5

0.5 1

1
0.5

0.5 1

1
0.5

0.5 1

1
0.5

0.5 1

1
0.5

0.5 1

0.5

0.5 1

0.5

0.5

1
0.5

0.5 ω c.m.

Θ cos F

P . Roy et al. [CLAS Collaboration], PRL 122, 162301 (2019)

Polarized Cross Section d σ d Ω = σ0 { 1 − δ l Σ cos 2φ + Λ x ( −δ l H sin 2φ + δ ⊙ F ) − Λ y ( −T + δ l P cos 2φ) − Λ z ( − δ l G sin 2φ + δ ⊙ E)}

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 31

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Helicity Asymmetry in γ p → p ω (CLAS g9a)

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

< 1.20 GeV

γ

1.10 < E

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

< 1.30 GeV

γ

1.20 < E

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

< 1.40 GeV

γ

1.30 < E

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

< 1.50 GeV

γ

1.40 < E

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

< 1.60 GeV

γ

1.50 < E

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

< 1.70 GeV

γ

1.60 < E

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

< 1.80 GeV

γ

1.70 < E

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

< 1.90 GeV

γ

1.80 < E

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

< 2.00 GeV

γ

1.90 < E

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

< 2.10 GeV

γ

2.00 < E

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

< 2.20 GeV

γ

2.10 < E

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

< 2.30 GeV

γ

2.20 < E

1

1

1

1

1

1

0.5

0.5 1

0.5

0.5 1

0.5

0.5 1

0.5

0.5 1

)

c.m. ω

θ cos(

Polarization Observable E

Z. Akbar et al. [CLAS Collaboration], PR C 96, 065209 (2017)
CLAS-g9a

CBELSA/TAPS

Phys. Lett. B 750, 453 (2015)

BnGa (coupled-channels) PWA Dominant I P exchange Complex 3/2+ wave

1

N(1720)

2

W ≈ 1.9 GeV N(1895) 1/2− (new state) N(1680), N(2000) 5/2+ 7/2 wave > 2.1 GeV

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 32

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Cross Sections for the Reaction γp → p ω → p π+π−π0

2.92 < W < 2.93 GeV 2.93 < W < 2.94 GeV 2.94 < W < 2.95 GeV 2.95 < W < 2.96 GeV 2.96 < W < 2.97 GeV

1 0 8 0 6 0 4 0 2 0 2 0 4 0 6 0 8 1

2.97 < W < 2.98 GeV

1 0 8 0 6 0 4 0 2 0 2 0 4 0 6 0 8 1

2.98 < W < 2.99 GeV

1 0 8 0 6 0 4 0 2 0 2 0 4 0 6 0 8 1

2.99 < W < 3.00 GeV

1 0 8 0 6 0 4 0 2 0 2 0 4 0 6 0 8 1

3.00 < W < 3.01 GeV

1 0 8 0 6 0 4 0 2 0 2 0 4 0 6 0 8 1

3.01 < W < 3.02 GeV 3.02 < W < 3.03 GeV 3.03 < W < 3.04 GeV 3.04 < W < 3.05 GeV 3.05 < W < 3.06 GeV 3.06 < W < 3.07 GeV 3.07 < W < 3.08 GeV 3.08 < W < 3.09 GeV 3.09 < W < 3.10 GeV 3.10 < W < 3.11 GeV 3.11 < W < 3.12 GeV

3

10

1

10 10

1

10 10

1

10 10

1

10 10

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5

1
0.5

0.5 1 c.m. ω

θ cos b] µ ) [ θ /d(cos σ d

➜ Data of unprecedented quality

New cross section results in 10-MeV-wide W bins for −1.15 < Eγ < 5.40 GeV, or −1.75 < W < 3.32 GeV ➜ Need theory support to understand physics at these high energies!! Working with JPAC.

(JPAC, V. Mathieu et al.)

Z. Akbar et al. [CLAS Collaboration], in preparation.
V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 33

Introduction Experimental Results Summary and Outlook The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

Decay modes of nucleon resonances

∗∗∗∗

Existence is certain. The impact of photoproduction black: PDG 2004

∗∗∗

Existence is very likely.

n baryon resonances

red: PDG 2018

∗∗

Evidence of existence is fair. blue: BESIII resonances

∗

Evidence of existence is poor.

verall

Nγ Nπ ∆π Nσ Nη ΛK ΣK Nρ Nω Nη′ N1440π N1520π N1535π N1680π N 1/2+ ∗∗∗∗ N(1440) 1/2+ ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗∗ N(1520) 3/2− ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗ ∗∗∗∗ N(1535) 1/2− ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗∗ ∗ ∗∗∗∗ N(1650) 1/2− ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗∗ ∗ ∗∗∗∗ ∗∗∗ ∗ N(1675) 5/2− ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗∗ ∗ ∗ ∗ ∗∗ ∗ N(1680) 5/2+ ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗∗ ∗ ∗∗∗∗ N(1700) 3/2− ∗∗∗ ∗∗ ∗∗∗ ∗∗∗ ∗ ∗ ∗∗ ∗ ∗ N(1710) 1/2+ ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗ ∗∗∗ ∗∗ ∗ ∗ ∗ ∗ N(1720) 3/2+ ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗∗ ∗ ∗ ∗∗∗∗ ∗ ∗∗ ∗ N(1860) 5/2+ ∗∗ ∗ ∗∗ ∗ ∗ N(1875) 3/2− ∗∗∗ ∗∗ ∗∗ ∗ ∗∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ N(1880) 1/2+ ∗∗∗ ∗∗ ∗ ∗∗ ∗ ∗ ∗∗ ∗∗ ∗∗ ∗ N(1895) 1/2− ∗∗∗∗ ∗∗∗∗ ∗ ∗ ∗ ∗∗∗∗ ∗∗ ∗∗ ∗ ∗ ∗∗∗∗ ∗ N(1900) 3/2+ ∗∗∗∗ ∗∗∗∗ ∗∗ ∗∗ ∗ ∗ ∗∗ ∗∗ ∗ ∗ ∗∗ N(1990) 7/2+ ∗∗ ∗∗ ∗∗ ∗ ∗ ∗ ∗∗ ∗∗ N(2000) 5/2+ ∗∗ ∗∗ ∗∗ ∗∗ ∗ ∗ ∗ ∗ ∗ N(2040) 3/2+ ∗ ∗ N(2060) 5/2− ∗∗∗ ∗∗∗ ∗∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ N(2100) 1/2+ ∗∗∗ ∗∗ ∗∗∗ ∗∗ ∗∗ ∗ ∗ ∗ ∗ ∗∗ ∗∗∗ N(2120) 3/2− ∗∗∗ ∗∗∗ ∗∗∗ ∗∗ ∗∗ ∗∗ ∗ ∗ ∗ ∗ ∗ ∗ N(2190) 7/2− ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗∗∗ ∗∗ ∗ ∗∗ ∗ ∗ ∗ N(2220) 9/2+ ∗∗∗∗ ∗∗ ∗∗∗∗ ∗ ∗ ∗ N(2250) 9/2− ∗∗∗∗ ∗∗ ∗∗∗∗ ∗ ∗ ∗ N(2300) 1/2+ ∗ ∗ N(2570) 5/2− ∗ ∗ N(2600) 11/2− ∗∗∗ ∗∗∗ N(2700) 13/2+ ∗∗ ∗∗

➜ ➜ ➜

Based on results at Jefferson Lab, ELSA, MAMI, ...

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 34

Introduction Experimental Results Summary and Outlook

Outline

1

Introduction Spectroscopy of Nucleon Resonances

2

Experimental Results The CLAS-g12 Experiment The γp → K 0 Σ+ → p π+π−π0 Channel The γp → p η → p π+π−π0 Channel The γp → p ω → p π+π−π0 Channel

3

Summary and Outlook

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 35

Introduction Experimental Results Summary and Outlook

The CLAS-g12 data set still contains a lot of physics: Among other analyses, cross section measurements of

γp → p η (Eγ < 4.7 GeV) Extending the CLAS-g11a results into the Regge regime; competing with GlueX on this reaction. JPAC is awaiting data ... γp → K 0 Σ+ (Eγ < 3.0 GeV) Important reaction in the seach for N∗ states; no CLAS data published, yet. γp → p ω (Eγ < 5.4 GeV) Extending the CLAS-g11a results into the Regge regime; JPAC is awaiting data ...

Determination of ω spin-densitymatrix elements(SDMEs) (Double-) polarization observables in γp → K 0 Σ+

V. Credé

Cross Section Measurements from CLAS-g12

SLIDE 36

Introduction Experimental Results Summary and Outlook

Acknowledgement This material is based upon work supported in part by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under Award Number DE-FG02-92ER40735.

V. Credé

Cross Section Measurements from CLAS-g12