[PPT] - Determination of the Hyperon Induced Polarization and PowerPoint Presentation

SLIDE 1

Determination of the Hyperon Induced Polarization and Polarization–Transfer Coefficients for Quasi-Free Hyperon Photoproduction off the Bound Neutron

NSTAR 2017 Colin Gleason

University of South Carolina

August 22, 2017 Work supported by NSF PHY-1505615

Colin Gleason (USC) August 22, 2017 1 / 25

SLIDE 2

Overview

Motivation for studying KΛ photoproduction Identification of the reaction of γd → K 0 Λ(p) → pπ+π−π−(p) Background subtraction Preliminary results

Comparison of Cx and P with current Bonn–Gatchina projections Comparison of Cz with K +Λ Dependence on neutron momentum First interpretations with Legendre polynomial fits

Summary

Colin Gleason (USC) August 22, 2017 2 / 25

SLIDE 3

Motivation for γd → K 0 Λ(p)

Majority of data is πN scattering or final states with π’s

Some resonances couple weakly to these channels while having significant branching ratios to KΛ

Most strangeness data from free proton

γp → K +Λ moving N(1900) 3

2 + from ∗∗ to ∗ ∗ ∗

γn → K 0Λ sensitive to ∗ ∗ N(2120) 3

2 − and

∗ ∗ ∗N(1875) 3

2 −

How do data from the proton and bound neutron compare to each

ther?

✐ ❢

⋆ ⋆ ⋆ ⋆

C. Patrignani et al. (Particle Data Group), Chin. Phys. C, 40, 100001 (2016).

Colin Gleason (USC) August 22, 2017 3 / 25

SLIDE 4

Polarization Observables in KΛ Photoproduction

The 4 complex scattering amplitudes can define 16 polarization observables

Unpolarized Cross Section σ0 Single P Σ T Beam-Recoil Cx Cz Ox Oz Target-Recoil Tx Tz Lx Lz Beam-Target E F G H

The full scattering amplitude can be determined by carefully choosing 8

bservables.

dσ dΩ = σ0[1 − PlinΣ cos 2φ − α cos θx(PlinOx sin 2φ + PcircCx) − α cos θy(−P +

PlinT cos 2φ) − α cos θz(PlinOz sin 2φ + PcircCz)]

Colin Gleason (USC) August 22, 2017 4 / 25

SLIDE 5

Defining Kinematics: γN → K Λ

Two different coordinate systems for KY photoproduction:

K0

Λ

γ x y z y0 z0 x0 p π−

~ Λ

x, y, z θ n

K0 → π+π−

θCM

K0

Observables are dependent on Eγ and θCM

K

The coordinate systems define θx, θy, θz Polarization of Λ depends on choice of axes

Colin Gleason (USC) August 22, 2017 5 / 25

SLIDE 6

Previous Studies of K 0Λ Photoproduction

Compton dσ

dΩ for

γd → K 0 Λ(p) (under review 2017)

Bonn–Gatchina multi–channel fit for γd → π−p(p), π−p → γn, γd → π0n(p), γd → ηn(p), γd → K +Σ− “Both solutions seem to describe γd → K +Σ−(p) and γd → K 0Λ(p) reasonable well.”

Need to include polarization observables in the fits to (a) resolve this ambiguity or (b) provide a new solution!

arXiv:1706.04748 [nucl-ex] Colin Gleason (USC) August 22, 2017 6 / 25

SLIDE 7

Experimental Facility

Hall–B (1997-2012) at Thomas Jefferson National Accelerator Facility (JLab)

Polarized electron beam Ee=2.0 and 2.6 GeV Photon tagger CEBAF Large Acceptance Spectrometer (CLAS) Target- p, d (polarized or unpolarized)

Eγ = Ee − Ee0 ≈ 0.95 − 0.2Ee

B.A. Mecking et al., Nucl. Instr. and Meth. A 503, 513 (2003) Colin Gleason (USC) August 22, 2017 7 / 25

SLIDE 8

Experimental Facility

Identification of K 0 and Λ: M(π+π−) and M(pπ−)

M(π+π−) =

(˜

pπ+ + ˜ pπ−)2 Fit peak with Gaussian, ±4σ cut

Counts/MeV )

2

Mass(GeV/c 0.4 0.45 0.5 0.55 0.6 20000 40000

MK0 = 0.497 GeV/c2 µ = 0.498 GeV/c2 Colin Gleason (USC) August 22, 2017 8 / 25

SLIDE 9

Experimental Facility

Identification of K 0 and Λ: M(π+π−) and M(pπ−)

M(π+π−) =

(˜

pπ+ + ˜ pπ−)2 Fit peak with Gaussian, ±4σ cut

Counts/MeV )

2

Mass(GeV/c 0.4 0.45 0.5 0.55 0.6 20000 40000

MK0 = 0.497 GeV/c2 µ = 0.498 GeV/c2

M(pπ−) =

(˜

pp + ˜ pπ−)2 Fit peak with Gaussian, ±4σ cut

Counts/(25 MeV) )

2

Mass(GeV/c 1.1 1.11 1.12 1.13 1.14 1.15 10000 20000

MΛ = 1.115 GeV/c2 µ = 1.116 GeV/c2 Colin Gleason (USC) August 22, 2017 8 / 25

SLIDE 10

Experimental Facility

Identification of K 0 and Λ: M(π+π−) and M(pπ−)

M(π+π−) =

(˜

pπ+ + ˜ pπ−)2 Fit peak with Gaussian, ±4σ cut

Counts/MeV )

2

Mass(GeV/c 0.4 0.45 0.5 0.55 0.6 20000 40000

MK0 = 0.497 GeV/c2 µ = 0.498 GeV/c2

M(pπ−) =

(˜

pp + ˜ pπ−)2 Fit peak with Gaussian, ±4σ cut

Counts/(25 MeV) )

2

Mass(GeV/c 1.1 1.11 1.12 1.13 1.14 1.15 10000 20000

MΛ = 1.115 GeV/c2 µ = 1.116 GeV/c2

pX < 0.2 GeV/c cut used to select the quasi–free events

Colin Gleason (USC) August 22, 2017 8 / 25

SLIDE 11

Experimental Facility

Background Channels: γd → K 0Λ(X)

Non–resonant, unpolarized γd → π+π−pπ−(p) Higher mass channels:

γd → K 0Σ0(p) → K 0Λ(γp) → π+π−pπ−(γp) γd → K 0Σ⋆0(p) → K 0Λ(π0p) → π+π−pπ−(π0p) γd → K ⋆(892)Λ(p) → K 0Λ(π0p) → π+π−pπ−(π0p)

)

2

(GeV/c

X

M 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 1.3 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000

X = p X = γp

0.9 1.0 1.1 1.2

20000

MX (GeV/c2)

Counts/(2.5 MeV/c2)

X = π0p

MX =

(˜

pγ + ˜ pd − ˜ pK0 − ˜ pΛ)2

Colin Gleason (USC) August 22, 2017 9 / 25

SLIDE 12

Experimental Facility

Background Channels: γd → K 0Λ(X)

Non–resonant, unpolarized γd → π+π−pπ−(p) Higher mass channels:

γd → K 0Σ0(p) → K 0Λ(γp) → π+π−pπ−(γp) γd → K 0Σ⋆0(p) → K 0Λ(π0p) → π+π−pπ−(π0p) γd → K ⋆(892)Λ(p) → K 0Λ(π0p) → π+π−pπ−(π0p)

)

2

(GeV/c

X

M 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 1.3 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000

X = p X = γp

0.9 1.0 1.1 1.2

20000

MX (GeV/c2)

Counts/(2.5 MeV/c2)

X = π0p

MX =

(˜

pγ + ˜ pd − ˜ pK0 − ˜ pΛ)2 Need a realistic event generator and simulations to separate signal from background

Colin Gleason (USC) August 22, 2017 9 / 25

SLIDE 13

Experimental Facility

Background Subtraction

Determine background free observable from ratios of background to signal events Done by fitting MX with the simulated background channels

Colin Gleason (USC) August 22, 2017 10 / 25

SLIDE 14

Experimental Facility

Background Subtraction

Determine background free observable from ratios of background to signal events Done by fitting MX with the simulated background channels 1 Fit Double Gaus+background histograms to data 2 Use fit parameters to normalize background 3 Calculate background to total ratios: rB and runpol

)

2

(GeV/c

X

M 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 1.3 5000 10000 15000 20000 25000

Fit Scaled

π
π

+

π p Scaled Σ K +K(892) Scaled

*0

Σ K

Colin Gleason (USC) August 22, 2017 10 / 25

SLIDE 15

Experimental Facility

Background Subtraction

Determine background free observable from ratios of background to signal events Done by fitting MX with the simulated background channels 1 Fit Double Gaus+background histograms to data 2 Use fit parameters to normalize background 3 Calculate background to total ratios: rB and runpol

)

2

(GeV/c

X

M 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 1.3 5000 10000 15000 20000 25000

Fit Scaled

π
π

+

π p Scaled Σ K +K(892) Scaled

*0

Σ K

A “total” observable can be extracted for regions 1 and 2 The total observable is corrected using the background to total ratios (rB

i , runpol i

) to get a “signal” (background free)

bservable

C S

x = rB

1 CT x,2−rB 2 CT x,1

rB

1 −rB 2 −rB 1 runpol 2

+runpol

1

rB

2

1: signal dominated, 2: K 0Σ0 dominated 1 2

Colin Gleason (USC) August 22, 2017 10 / 25

SLIDE 16

Experimental Facility

Cx–Polarization Transfer from γ to Λ Along x–axis

x

C

CM K

θ cos

1

1

1

1

Preliminary

<1.0

γ

E

Preliminary

<1.4

γ

1.3<E

Preliminary

<1.8

γ

1.7<E

Preliminary

<2.2

γ

2.1<E

Preliminary

<1.1

γ

1.0<E

Preliminary

<1.5

γ

1.4<E

Preliminary

<1.9

γ

1.8<E

Preliminary

<2.3

γ

2.2<E

Preliminary

<1.2

γ

1.1<E

Preliminary

<1.6

γ

1.5<E

Preliminary

<2.0

γ

1.9<E

Preliminary

<2.4

γ

2.3<E

Preliminary

<1.3

γ

1.2<E

Preliminary

<1.7

γ

1.6<E

Preliminary

<2.1

γ

2.0<E

Preliminary

>2.4

γ

E

Two BonnGa solutions from fits to K 0Λ cross–sections Same resonances included, two sets of parameters give reasonable fit to γd → K +Σ−(p) and K 0Λ(p) BonnGa provided me with the two solution’s projected onto Cx, Cz, P No K 0Λ polarization

bservables included

in fits Potential impact: resolution of current ambiguity, or lead to new results

Colin Gleason (USC) August 22, 2017 11 / 25

SLIDE 17

Experimental Facility

P–Λ Recoil Polarization

P

CM K

θ cos

1

1

1

1

Preliminary

<1.0

γ

E

Preliminary

<1.4

γ

1.3<E

Preliminary

<1.8

γ

1.7<E

Preliminary

<2.2

γ

2.1<E

Preliminary

<1.1

γ

1.0<E

Preliminary

<1.5

γ

1.4<E

Preliminary

<1.9

γ

1.8<E

Preliminary

<2.3

γ

2.2<E

Preliminary

<1.2

γ

1.1<E

Preliminary

<1.6

γ

1.5<E

Preliminary

<2.0

γ

1.9<E

Preliminary

<2.4

γ

2.3<E

Preliminary

<1.3

γ

1.2<E

Preliminary

<1.7

γ

1.6<E

Preliminary

<2.1

γ

2.0<E

Preliminary

>2.4

γ

E

Two BonnGa solutions from fits to K 0Λ cross–sections Same resonances included, two sets of parameters give reasonable fit to γd → K +Σ−(p) and K 0Λ(p) BonnGa provided me with the two solution’s projected onto Cx, Cz, P No K 0Λ polarization

bservables included

in fits Potential impact: resolution of current ambiguity, or lead to new results

Colin Gleason (USC) August 22, 2017 12 / 25

SLIDE 18

Experimental Facility

Cz: Comparison of γd → K 0Λ(p) to γp → K +Λ

0.5 − 0.5 1 1 − 1

<1.0

γ

E <1.0

γ

E

0.5 − 0.5 1 1 − 1

<1.4

γ

1.3<E <1.4

γ

1.3<E

0.5 − 0.5 1 1 − 1

<1.8

γ

1.7<E <1.8

γ

1.7<E

0.5 − 0.5 1 1 − 1

<2.2

γ

2.1<E <2.2

γ

2.1<E

0.5 − 0.5 1 1 1

<1.1

γ

1.0<E <1.1

γ

1.0<E

0.5 − 0.5 1 1 1

<1.5

γ

1.4<E <1.5

γ

1.4<E

0.5 − 0.5 1 1 1

<1.9

γ

1.8<E <1.9

γ

1.8<E

0.5 − 0.5 1 1 1

<2.3

γ

2.2<E <2.3

γ

2.2<E

0.5 − 0.5 1 1 1

<1.2

γ

1.1<E <1.2

γ

1.1<E

0.5 − 0.5 1 1 1

<1.6

γ

1.5<E <1.6

γ

1.5<E

0.5 − 0.5 1 1 1

<2.0

γ

1.9<E <2.0

γ

1.9<E

0.5 − 0.5 1 1 1

<2.4

γ

2.3<E <2.4

γ

2.3<E

0.5 − 0.5 1 1 1

<1.3

γ

1.2<E <1.3

γ

1.2<E

0.5 − 0.5 1 1 1

<1.7

γ

1.6<E <1.7

γ

1.6<E

0.5 − 0.5 1 1 1

<2.1

γ

2.0<E <2.1

γ

2.0<E

0.5 − 0.5 1 1 1

>2.4

γ

E >2.4

γ

E

cosθCM

K

Cz

γd → K 0Λ(p) γp → K +Λ

R. K. Bradford et al. (CLAS Collaboration), Phys. Rev. C 75, 035205

Colin Gleason (USC) August 22, 2017 13 / 25

SLIDE 19

Experimental Facility

Dependence on Neutron Momentum

<1.1125 GeV

γ

E <1.1125 GeV

γ

E

<1.9625 GeV

γ

1.750<E <1.9625 GeV

γ

1.750<E

<1.3250 GeV

γ

1.1125<E <1.3250 GeV

γ

1.1125<E <2.1750 GeV

γ

1.9625<E <2.1750 GeV

γ

1.9625<E <1.5375 GeV

γ

1.3250<E <1.5375 GeV

γ

1.3250<E <2.3875 GeV

γ

2.1750<E <2.3875 GeV

γ

2.1750<E <1.750 GeV

γ

1.5375<E <1.750 GeV

γ

1.5375<E <2.6000 GeV

γ

2.3875<E <2.6000 GeV

γ

2.3875<E

Neutron Momentum (GeV/c)

z

C 0.5

1

1

Momentum (GeV/c) 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1000 2000 3000 4000 5000 6000 7000 8000 9000 X Missing Momentum pX Missing Momentum p

Neutron Momentum

0.2 0.6

1

1

γ

n

p p Λ

K0

Neutron is not free
Need free neutron for

CCA

How well do the
bservables

represent the free neutron?

14% 11% 1% 20% 2% 6% 88% 15% Cz Neutron Momentum

Colin Gleason (USC) August 22, 2017 14 / 25

SLIDE 20

Experimental Facility

First Interpretation: Legendre Polynomial Fits

The goal is to determine the dominant partial wave contribution to the observables, O = O dσ

dΩ, using an expansion of Legendre

polynomials Cx = ρ

2Lmax+1

k=1

(aL)Cx

k P1 k(cos θ),

(1) Cz = ρ

2Lmax+1

k=0

(aL)Cz

k P0 k(cos θ),

(2) P = ρ

2Lmax

k=1

(aL)P

k P1 k(cos θ).

(3) The procedure is to fit O and determine the Lmax where the χ2 → 1. This is not to replace PWA, but is instead a complimentary tool.

Y. Wunderlich, F. Afzal, A. Thiel and R. Beck, Eur. Phys. J. A53, no. 5, 86 (2017)

Colin Gleason (USC) August 22, 2017 15 / 25

SLIDE 21

Experimental Facility

First Interpretation: Legendre Polynomial Fits to Cx

1.6 1.8 2 2.2 2.4 5

L=0 L=1 L=2 L=3 W (GeV)

2

χ θ cos Ω d σ d

x

C

1 − 0.5 − 0.5 1 1 − 1

<1.0

γ

E

1 0.5 0.5 1 1 − 1

<1.4

γ

1.3<E

1 0.5 0.5 1 0.2 − 0.2

<1.8

γ

1.7<E

1 − 0.5 − 0.5 1 0.1 − 0.1

<2.2

γ

2.1<E

1 − 0.5 − 0.5 1 1 1

<1.1

γ

1.0<E

1 0.5 0.5 1 1 1

<1.5

γ

1.4<E

1 0.5 0.5 1 0.2 0.2

<1.9

γ

1.8<E

1 − 0.5 − 0.5 1 0.1 0.1

<2.3

γ

2.2<E

1 − 0.5 − 0.5 1 1 1

<1.2

γ

1.1<E

1 0.5 0.5 1 1 1

<1.6

γ

1.5<E

1 0.5 0.5 1 0.2 0.2

<2.0

γ

1.9<E

1 − 0.5 − 0.5 1 0.1 0.1

<2.4

γ

2.3<E

1 − 0.5 − 0.5 1 1 1

<1.3

γ

1.2<E

1 0.5 0.5 1 1 1

<1.7

γ

1.6<E

1 0.5 0.5 1 0.2 0.2

<2.1

γ

2.0<E

1 − 0.5 − 0.5 1 0.1 0.1

>2.4

γ

E

1 −1 1 −1 −0.2 0.2 0.2 −0.2

Cx

cos θ

0.5 −0.5 0.5 −0.5 0.5 −0.5 0.5 −0.5

1.6 1.8 2.0 2.2 2.4

χ2

W (GeV)

cos θCM

K0

P r e l i m i n a r y

5

Lmax = 0: S–wave Lmax = 1: P–wave Lmax = 2: D–wave Lmax = 3: F–wave

Colin Gleason (USC) August 22, 2017 16 / 25

SLIDE 22

Experimental Facility

First Interpretation: Legendre Polynomial Fits to Cx

1.6 1.8 2 2.2 2.4 5

L=0 L=1 L=2 L=3 W (GeV)

2

χ θ cos Ω d σ d

x

C

1 − 0.5 − 0.5 1 1 − 1

<1.0

γ

E

1 0.5 0.5 1 1 − 1

<1.4

γ

1.3<E

1 0.5 0.5 1 0.2 − 0.2

<1.8

γ

1.7<E

1 − 0.5 − 0.5 1 0.1 − 0.1

<2.2

γ

2.1<E

1 − 0.5 − 0.5 1 1 1

<1.1

γ

1.0<E

1 0.5 0.5 1 1 1

<1.5

γ

1.4<E

1 0.5 0.5 1 0.2 0.2

<1.9

γ

1.8<E

1 − 0.5 − 0.5 1 0.1 0.1

<2.3

γ

2.2<E

1 − 0.5 − 0.5 1 1 1

<1.2

γ

1.1<E

1 0.5 0.5 1 1 1

<1.6

γ

1.5<E

1 0.5 0.5 1 0.2 0.2

<2.0

γ

1.9<E

1 − 0.5 − 0.5 1 0.1 0.1

<2.4

γ

2.3<E

1 − 0.5 − 0.5 1 1 1

<1.3

γ

1.2<E

1 0.5 0.5 1 1 1

<1.7

γ

1.6<E

1 0.5 0.5 1 0.2 0.2

<2.1

γ

2.0<E

1 − 0.5 − 0.5 1 0.1 0.1

>2.4

γ

E

1 −1 1 −1 −0.2 0.2 0.2 −0.2

Cx

cos θ

0.5 −0.5 0.5 −0.5 0.5 −0.5 0.5 −0.5

1.6 1.8 2.0 2.2 2.4

χ2

W (GeV)

cos θCM

K0

P r e l i m i n a r y

5

Lmax = 0: S–wave Lmax = 1: P–wave Lmax = 2: D–wave Lmax = 3: F–wave Lmax = 0: ∗ ∗ ∗ ∗ N(1650) 1

2 −, ∗ ∗N(1895) 1 2 −

Lmax = 1: ∗ ∗ ∗ ∗ N(1710) 1

2 +, ∗ ∗ ∗ ∗N(1720) 3 2 −, ∗ ∗N(1880) 1 2 +, ∗ ∗ ∗ N(1900) 3 2 +

Lmax = 2: ∗ ∗ ∗ ∗ N(1675) 5

2 −, ∗ ∗ ∗ N(1700) 3 2 −, ∗ ∗ ∗ N(1875) 3 2 −, ∗ ∗N(2120) 3 2 −

Cx Cz P

Lmax = 0: ∗ ∗ ∗ ∗ N(1650) 1

2 −, ∗ ∗N(1895) 1 2 −

Lmax = 1: ∗ ∗ ∗ ∗ N(1710) 1

2 +, ∗ ∗ ∗ ∗N(1720) 3 2 −, ∗ ∗N(1880) 1 2 +, ∗ ∗ ∗ N(1900) 3 2 +

Lmax = 2: ∗ ∗ ∗ ∗ N(1675) 5

2 −, ∗ ∗ ∗ N(1700) 3 2 −, ∗ ∗ ∗ N(1875) 3 2 −, ∗ ∗N(2120) 3 2 −

Lmax = 3: ∗ ∗ N(2000) 5

2 + Colin Gleason (USC) August 22, 2017 17 / 25

SLIDE 25

Experimental Facility

Conclusions and Outlook

Studying KΛ photoproduction is needed in the search for N∗ > 1800 MeV

Significant work has been done to study K +Λ, but more data is needed

n this and other channels, like K 0Λ

I have extracted the first estimates for Cx, Cz, and P for

γd → K 0

Λ(p). There are similarities and differences observed in data from free proton (isopsin, reaction dynamics, other resonances). Disagreement between current Bonn–Gatchina “predictions” and my results

My results should have an impact on new fits (resolve fit ambiguity, new N∗?)

Legendre fits: Lmax = 2 (D–wave) dominance in Cz suggesting presence of N(1875) 3

2 − and/or N(2120) 3 2 −?

Colin Gleason (USC) August 22, 2017 18 / 25

SLIDE 26

Experimental Facility

Backup

Colin Gleason (USC) August 22, 2017 19 / 25

SLIDE 27

Experimental Facility

Previous Studies of KΛ Photoproduction

Bradford γp → K + Λ (2006) CLAS Collaboration Kaon–MAID SAP Bonn–Ga RPR Gent GLV (dash)

Cz is the polarization transfer from the circularly polarized beam to the Λ along the z–axis Hadronic model predictions are in poor agreement with these results This work, in combination with

ther K +Λ
bservables led to the

promotion of N(1900) 3

2 + from **

to ***

R. K. Bradford et al. (CLAS Collaboration), Phys. Rev. C 75, 035205

Colin Gleason (USC) August 22, 2017 20 / 25

SLIDE 28

Experimental Facility

Previous Studies of KΛ Photoproduction

Paterson γp → K + Λ (2016) CLAS

Osaka group fit (N∗ < 2GeV ), 2014 BG fit, new BG fit to all observables “... data set shows some evidence of resonances beyond the 2014 solution, but that it is not strong enough to deduce the quantum numbers or masses of these states or indeed conclusively support their existence.”

C.A. Paterson et al. (CLAS Collaboration) Phys. Rev. C 93, 065201 (2016) Colin Gleason (USC) August 22, 2017 21 / 25

SLIDE 29

Experimental Facility

MX Fits Example: 2.2 < Eγ < 2.3 GeV

Counts/MeV )

2

Mass(GeV/c

50 100

<-0.4

CM K

θ cos

50

<0.1

CM K

θ

0.0<cos

0.8 1 1.2 100 200

<0.6

CM K

θ 0.5<cos

20 40 60 <-0.3 CM K θ

0.4<cos

50 100

<0.2

CM K

θ 0.1<cos

0.8 1 1.2 100 200

<0.7

CM K

θ 0.6<cos

20 40 60 <-0.2 CM K θ

0.3<cos

50 100

<0.3

CM K

θ 0.2<cos

0.8 1 1.2 50 100 150

>0.8

CM K

θ 0.7<cos

20 40 60 <-0.1 CM K θ

0.2<cos

100 200

<0.4

CM K

θ 0.3<cos

0.8 1 1.2 20 40 60

>0.8

CM K

θ cos

50 <-0.0 CM K θ

0.1<cos

100 200

<0.5

CM K

θ 0.4<cos

Colored histograms scaled using the corresponding fit parameter. Higher mass states included to get fit correct. Excluded from

bservable extraction

by cut at 1.05 GeV/c2 γd → K 0Λ(X), X = p, γp, π0p

Colin Gleason (USC) August 22, 2017 22 / 25

SLIDE 30

Experimental Facility

R =

C 2

x + C 2 z + P2: Total Polarization Transfer

0.5 − 0.5

1 2

<1.0

γ

E

0.5 − 0.5

1 2 <1.4

γ

1.3<E

0.5 − 0.5

1 2 <1.8

γ

1.7<E

0.5 − 0.5

1 2

<2.2

γ

2.1<E

0.5 − 0.5

1 2 <1.1

γ

1.0<E

0.5 − 0.5

1 2 <1.5

γ

1.4<E

0.5 − 0.5

1 2 <1.9

γ

1.8<E

0.5 − 0.5

1 2

<2.3

γ

2.2<E

0.5 − 0.5

1 2 <1.2

γ

1.1<E

0.5 − 0.5

1 2 <1.6

γ

1.5<E

0.5 − 0.5

1 2 <2.0

γ

1.9<E

0.5 − 0.5

1 2

<2.4

γ

2.3<E

0.5 − 0.5

1 2 <1.3

γ

1.2<E

0.5 − 0.5

1 2 <1.7

γ

1.6<E

0.5 − 0.5

1 2 <2.1

γ

2.0<E

0.5 − 0.5

1 2

>2.4

γ

E

Low Eγ– Λ fully polarized Mid Eγ– Λ fully polarized at forward and backward angles High Eγ– large uncertainties, but Λ near full polarizations within uncertainties

cosθCM

K

R

Colin Gleason (USC) August 22, 2017 23 / 25

SLIDE 31

Experimental Facility

P Comparison with Different Predictions

P

CM K

θ cos

1

1

1

1

<1.0

γ

E <1.4

γ

1.3<E <1.8

γ

1.7<E

<2.2

γ

2.1<E

<1.1

γ

1.0<E <1.5

γ

1.4<E <1.9

γ

1.8<E

<2.3

γ

2.2<E

<1.2

γ

1.1<E <1.6

γ

1.5<E <2.0

γ

1.9<E

<2.4

γ

2.3<E

<1.3

γ

1.2<E <1.7

γ

1.6<E <2.1

γ

2.0<E

>2.4

γ

E

Comparison of P to Kaon–MAID (soild) and Waluyo Ph.D. thesis (dashed) With N(1900) 3

2

Without N(1900) 3

2

A new fit to K 0Λ with inclusion of all channels would help constrain amplitudes for N(1900) 3

2 , and

maybe provide information about

ther states like

N(2120)

Colin Gleason (USC) August 22, 2017 24 / 25

SLIDE 32

Experimental Facility

Dependence on Neutron Virtuality

0.1 Obs. 1 − 1

<1.1125 GeV

γ

E <1.1125 GeV

γ

E

2

)

2

Virtuality (GeV/c 0.1 Obs. 1 − 1

<1.9625 GeV

γ

1.750<E <1.9625 GeV

γ

1.750<E

0.1 1 1

<1.3250 GeV

γ

1.1125<E <1.3250 GeV

γ

1.1125<E

2

)

2

Virtuality (GeV/c 0.1 1 1

<2.1750 GeV

γ

1.9625<E <2.1750 GeV

γ

1.9625<E

0.1 1 1

<1.5375 GeV

γ

1.3250<E <1.5375 GeV

γ

1.3250<E

2

)

2

Virtuality (GeV/c 0.1 1 1

<2.3875 GeV

γ

2.1750<E <2.3875 GeV

γ

2.1750<E

0.1 1 1

<1.750 GeV

γ

1.5375<E <1.750 GeV

γ

1.5375<E

2

)

2

Virtuality (GeV/c 0.1 1 1

<2.6000 GeV

γ

2.3875<E <2.6000 GeV

γ

2.3875<E

1

1

γ

n

p p Λ

K0

Neutron is not free
Virtuality describes

the off-shellness of the neutron

How well do the
bservables

represent the free neutron?

1 10

2

10

3

10 neut

Virtuality vs. P

Momentum (GeV/c) 0.2 0.4 0.6 0.8 1 1.2

2

)

2

Virtuality (GeV/c 0.5 1 1.5 2 neut

Virtuality vs. P

0.0 0.1 Virtuality=m2

n − t = m2 n − [˜

pγ − ˜ pK0 − ˜ pΛ]2

Virt. vs. ~

pn Cz Cx P

Colin Gleason (USC) August 22, 2017 25 / 25