Electromagnetic Nuclear Physics Overview Seamus Riordan Stony Brook - - PowerPoint PPT Presentation

SLIDE 1

Electromagnetic Nuclear Physics Overview

Seamus Riordan Stony Brook University seamus.riordan@stonybrook.edu June 17, 2015

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

1/30

SLIDE 2

EM Nuclear Physics Overview

... summarize the current experimental situation, and highlight

• pportunities for progress with high-current electron beams in the

10-500 MeV energy range. 10-500 MeV range covers:

E ∼Few 100 MeV - nucleon properties, lowest resonances E > π - π at threshold E ∼ Few - 10s MeV - Nuclear excitations

Both real and virtual γ interactions have been critical in our understanding

• f the strong nuclear force

Broadly FF, neutron, isovector, and polarization observables are popular experimental areas

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 3

Nucleon Structure

Protons and neutrons are the “ground state” of QCD E < 500 MeV probes non-perturbative structures Important to consider elastic processes (static structure), polarizabilities, and intermediate state properties

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

3/30

SLIDE 4

Form Factors for Nucleons

Scattering matrix element, M ∼ jµJµ

Q2

Generalizing to spin 1/2 with arbitrary structure, one-photon exchange, using parity conservation, current conservation the current parameterized by two form factors Jµ = e ¯ u(p′)

• F1(q2)γν + i κ

2M qνσµνF2(q2)

• u(p)

Form Factors Dirac - F1, chirality non-flip Pauli - F2, chirality flip

µ

p

µ

p’ J j µ

µ µ

q Seamus Riordan — Cornell IEB 2015

• Nucl. EM

4/30

SLIDE 5

Sachs Form Factors

Replace with Sachs Form Factors

GE = F1 − κτF2 GM = F1 + κF2

Limit as Q2 → 0 G p

E(Q2 = 0) = 1,

G p

M(Q2 = 0) = µp =

2.79 G n

E(Q2 = 0) = 0,

G n

M(Q2 = 0) = µn =

−1.91 −6dGEM dQ2

• Q2→0 = r2

EM

Rosenbluth Formula dσ dΩ = dσ dΩ

• Mott

E ′ E

• G 2

E + τG 2 M

1 + τ + 2τG 2

M tan2 θ

2

• , τ = Q2

4M2

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 6

GE/GM through Spin Observables

Akhiezer and Rekalo (1968) - Polarization offers access to GE/GM Typically have fewer systematic contributions from nuclear structure and radiative effects Polarization Transfer, eN, e′ N′ GE GM = −Pt Pl (Ee + Ee′) tan θe/2 2M Polarized Beam/Target e N, e′N′

A⊥ = − 2

• τ(τ + 1) tan(θ/2)GE /GM

(GE /GM)2 + (τ + 2τ(1 + τ) tan2(θ/2))

θ∗ e e’ θ φ∗ e polarization axis ω, q momentum transfer

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 7

Proton Results

G p

M generally follow dipole -

exponential distribution GD = 1

• 1 + Q2/(0.71 GeV2)

2

]

2

[GeV

2

Q

• 2

10

• 1

10 1 10 D

G

p

µ /

p M

G

0.9 1.0 1.1

Borkowski Sill Bosted Walker Andivahis

]

2

[GeV

2

Q

• 1

10 1 10 p M

/G

p E

G

p

µ

0.0 0.5 1.0 1.5

Janssens Bartel Litt Berger Walker Andivahis Christy

JLab, Jones et al., G p

E different from G n M using polarization

Neglect of hard two-photon exchange can cause systematic errors in extraction Results testing this are now being produced

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

7/30

SLIDE 8

Proton Results

G p

M generally follow dipole -

exponential distribution GD = 1

• 1 + Q2/(0.71 GeV2)

2

]

2

[GeV

2

Q

• 2

10

• 1

10 1 10 D

G

p

µ /

p M

G

0.9 1.0 1.1

Borkowski Sill Bosted Walker Andivahis

]

2

[GeV

2

Q

2 4 6 8 10 p M

/G

p E

G

p

µ

0.0 0.5 1.0 Punjabi Gayou Puckett Reanalysis Puckett RCQM - G. Miller (2005)

• Cloet (2012)

π Diquark

JLab, Jones et al., G p

E different from G n M using polarization

Neglect of hard two-photon exchange can cause systematic errors in extraction Results testing this are now being produced

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

7/30

SLIDE 9

Two-photon Exchange Results - CLAS, VEPP-III

Results from CLAS and VEPP-III with e+/e− available Kinematic coverage over broad ǫ and Q2 up to ∼ 1.5 GeV2 Both show definite effects of exchange and agreement with reconciliation

2

(GeV/c)

2

Q 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 p)

• (e
• p)

+

(e

• R’ =

0.98 0.99 1 1.01 1.02 1.03 1.04 World data CLAS TPE Zhou and Yang (N only) Blunden et al. (N only) )

• Zhou and Yang (N+

Point-like proton

• D. Adikaram et al
• Phys. Rev. Lett. 114, 062003

0.0 0.2 0.4 0.6 0.8 1.0 0.99 1.00 1.01 1.02 1.03 1.04 LNP 0.5 1 1.5 2

ε

Q2 (GeV2)

R2γ

0.0 0.2 0.4 0.6 0.8 1.0 0.99 1.00 1.01 1.02 1.03 1.04 LNP 0.2 0.4 0.6 0.8 1 1.2

ε

Q2 (GeV2)

R2γ

I.A. Rachek et al

• Phys. Rev. Lett. 114, 062005

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

8/30

SLIDE 10

Two-photon Exchange Results - OLYMPUS

OLYMPUS at DESY - Milner et al e+/e− ratio Will provide data up to Q2 = 2.2 GeV2 at 1% level Higher Q2 in addition with

• ther data will provide

stronger constraints Ended running in 2013 - Under analysis with hope for results at the end of 2015

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

9/30

SLIDE 11

Discrepancy with Muonic Hydrogen Lamb Shift

Lamb shift breaks degeneracy in 2S1/2 and 2P1/2 - Hyperfine splitting, is sensitive to

• r2

p

µ-hydrogen more sensitive due to smaller Bohr radius, increases as m3, mµ/me ∼ 200

H.S. Margolis, Science 339, 405 (2013)

e(p, e′) and spectroscopy agree µ − H2 off by more than 6σ! Missing QED effects? Proton distorting? New coupling to just µ−? Tie to gµ − 2 problem? Theory and experiment review: Pohl et al. Annu. Rev. Nucl. Part. Sci

• 2013. 63: 175-204

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

10/30

SLIDE 12

Mainz low Q2 G p

E results

J.C. Bernauer et al. PRL 105, 242001 (2010)

• Rosen. Sep.

Rosenbluth separation of over 1400 cross sections from Mainz, Q2 up to 1 GeV2 Results have some systematic discrepancies with previous experiments - normalization errors Includes two photon effects, proton radiative effects not large

0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 1.1 0.2 0.4 0.6 0.8 1 GM/(µpGstd. dipole) [13] [2] Christy et al. Price et al. Berger et al. Hanson et al. Borkowski et al. [15] Janssens et al. Bosted et al. Bartel et al. 0.75 0.8 0.85 0.9 0.95 1 1.05 1.1 0.2 0.4 0.6 0.8 1 µpGE/GM Q2 / (GeV/c)2 [13] w/o TPE [13] w/ TPE [2] Crawford et al. Gayou et al. Milbrath et al. Punjabi et al. Jones et al. Pospischil et al. Dieterich et al. Ron et al. [17]

r2

E1/2 = 0.879 ± 0.008 fm, consistent

r2

M1/2 = 0.777 ± 0.016 fm, smaller by about 0.1 fm!

r2

M1/2 = 0.85 ± 0.03 fm from other global fit (Zhan et al.)

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

11/30

SLIDE 13

Latest low Q2 G p

E results

• X. Zhan et al.
• Phys. Lett. B 705, 59 (2011)
• Pol. Trans.

0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 1.1 0.2 0.4 0.6 0.8 1 GM/(µpGstd. dipole) [13] [2] Christy et al. Price et al. Berger et al. Hanson et al. Borkowski et al. [15] Janssens et al. Bosted et al. Bartel et al. 0.75 0.8 0.85 0.9 0.95 1 1.05 1.1 0.2 0.4 0.6 0.8 1 µpGE/GM Q2 / (GeV/c)2 [13] w/o TPE [13] w/ TPE [2] Crawford et al. Gayou et al. Milbrath et al. Punjabi et al. Jones et al. Pospischil et al. Dieterich et al. Ron et al. [17]

Discrepancy with other data, but G p

E slope values are in agreement

with Bernauer Bernauer magnetic radius from new unseen “wiggle” JLab data from 0.01 − 0.08 GeV2 with polarized target under analysis.

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

12/30

SLIDE 14

Latest low Q2 G p

E results

• X. Zhan et al.
• Phys. Lett. B 705, 59 (2011)
• Pol. Trans.

0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 1.1 0.2 0.4 0.6 0.8 1 GM/(µpGstd. dipole) [13] [2] Christy et al. Price et al. Berger et al. Hanson et al. Borkowski et al. [15] Janssens et al. Bosted et al. Bartel et al. 0.75 0.8 0.85 0.9 0.95 1 1.05 1.1 0.2 0.4 0.6 0.8 1 µpGE/GM Q2 / (GeV/c)2 [13] w/o TPE [13] w/ TPE [2] Crawford et al. Gayou et al. Milbrath et al. Punjabi et al. Jones et al. Pospischil et al. Dieterich et al. Ron et al. [17]

Discrepancy with other data, but G p

E slope values are in agreement

with Bernauer Bernauer magnetic radius from new unseen “wiggle” JLab data from 0.01 − 0.08 GeV2 with polarized target under analysis.

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

12/30

SLIDE 15

New Charge Radius Measurements

MUSE at PSI

Gilman et al. Elastic µ− and µ+ Q2 = 0.002 − 0.07 GeV2

PRad

Gasparian et al. Very low Q2 e− Q2 = 2 × 10−4 − 0.14 GeV2 No magnetic elements - high precision calorimeter

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

13/30

SLIDE 16

Precision Radius Measurements - Under Analysis

Data taken at Mainz will use initial state radiation reaches to effectively low Q2 Will extend to Q2 ∼ 10−4 GeV2 Under analysis - preliminary results in weeks?

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

14/30

SLIDE 17

Recent Lattice

Scalar

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 0.0 0.1 0.2 0.3 0.4 0.5 Gs

E

Q2 (GeV2) Alberico et al parametrization lattice data 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0.0 0.1 0.2 0.3 0.4 0.5 Gs

M

Q2 (GeV2) Alberico et al parametrization lattice data

Vector

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 0.0 0.1 0.2 0.3 0.4 0.5 Gv

E

Q2 (GeV2) Alberico et al parametrization lattice data 1 2 3 4 5 6 0.0 0.1 0.2 0.3 0.4 0.5 Gv

M

Q2 (GeV2) Alberico et al parametrization lattice data

mπ = 149 MeV, Q2 to 0.5 GeV2 Can’t differentiate between two proton radii results (though quoted errors are about the difference)

Green et al. arXiv:1404.4029 [hep-lat]

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

15/30

SLIDE 18

Neutron Status

Neutron form factor data is challenging: No free neutron targets and G n

E is small

Data has been consistant at low Q2 Medium Q2 polarization data has one high point which has been suggested to be looked at

]

2

[GeV

2

Q

5 10 D

G

n

µ /

n M

G

0.4 0.6 0.8 1.0 1.2

Rock Lung Markowitz Anklin(1994) Bruins Anklin(1998) Kubon Lachniet

VMD - Lomon (2002) CQM - Miller (2002)

]

2

[GeV

2

Q

n M

/G

n E

G

n

µ

0.0 0.2 0.4 0.6 0.8

P R E L I M I N A R Y

RCQM - Miller (2006) VMD - Lomon (2005) DSE - Cloet (2010) = 300 MeV Λ ,

1

/F

2

F Our Fit

Passchier, NIKHEF Herberg, MAMI Ostrick, MAMI Meyerhoff, MAMI Golak, MAMI Bermuth, MAMI Plaster, JLab Zhu, JLab Warren, JLab Glazier, MAMI Geis, BATES Schlimme, MAMI e'D, JLab Hall A (prelim) Riordan E02-013 Preliminary

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Neutron MS radius done from thermal neutron scattering on electrons r2

n = -0.1161 fm

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 19

Nucleon Polarizabilities

Polarizabilities with real photons also probe fundamental properties Six indepdentent scattering amplitudes

Lowest order probe E and B responses Four higher order spin observables ( γ p, γp) give spin polarizabilities

Several basic sum rules to be comprehensively tested

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

17/30

SLIDE 20

Proton Scalar Polarizabilities

Best data from 55-156 MeV w/ TAPS at MAMI

dσ dΩ = dσ dΩ

• Born − ωω′

ω′ ω 2 e2 m × α + β 2 (1 + cos θ)2 + α − β 2 (1 − cos θ)2

• Baldin-Lapidus sum rule:

α + β = 1 2π ∞

ω0

σtot(ω) ω2 dω

de Leon et al., Eur.Phys.J. A10 (2001) 207

Global results: α = [12.1 ± 0.3(stat) ± 0.4(sys) ± 0.3(mod)] × 10−4fm3 β = [1.6 ± 0.4(stat) ± 0.4(sys) ± 0.4(mod)] × 10−4fm3

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

18/30

SLIDE 21

Proton Spin Polarizabilities

H(3)

eff

= −4π

• 1

2 σ ·

• E × ˙
• E
• + 1

2γM1M1 σ ·

• H × ˙
• H
• −γM1E2EijσiHj + γE1M2HijσiEj
• Four terms at H(3)

Requires several spin

• bservables for complete

determination γ0 can come from DR

Forward and backward polarizabilities: γ0 = −γE1E1 − γE1M2 − γM1E2 − γM1M1 = − 1 4π ∞

ω0

σ3/2 − σ1/2 ω3 dω γπ = −γE1E1 − γE1M2 + γM1E2 + γM1M1

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 22

Proton Spin Polarizabilities

Combination of LEGS and recent Mainz data with polarized beam/target determines polarizabilities Dominated by statistical uncertainties - much room for improvement with large statistics

P.P. Martel et al, PRL 114, 112501 (2015)

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 23

Neutron Polarizabilities

Neutron much less well determined especially outside of DR Analysis primarily done in γd reactions, potentially 3He αn = 12.5 ± 1.8(stat)+1.1

−0.6(sys) ± 1.1(model) × 10−4fm3

βn = 2.7 ± 1.8(stat)+0.6

−1.1(sys) ± 1.1(model) × 10−4fm3 Levchuk MI, L’vov AI. Nucl. Phys. A 674:449 (2000) Kossert K, et al. Eur. Phys. J. A 16:259 (2003)

Provides test of HBχPT with relations between p and n polarizabilities αp = αn, βp = βn = α/10 γp

0 = γn 0 = 8

10 1 πmπ α γp

π = −γp

12 gA − 1

• γn

π = −γp

12 gA + 1

• Seamus Riordan — Cornell IEB 2015
• Nucl. EM

21/30

SLIDE 24

GDH Sum Rule

GDH sum rule one of the best known and tested dispersion relations in NP ∞

ω0

σ3/2 − σ1/2 ω dω = 2π2α m2 κ2 Proton tested to ∼8% level Neutron remains a challenge with very little data! Low energy and nuclear binding effects are an issue Polarized 3He efforts at facilities like HIγS offer

• pportunities for data and

testing 3 body calculations

Helbing, Prog. Part. Nucl. Phys. 57 (2006) 405

Recent 3He Result:

Laskaris et al, arXiv:1506.00332 Seamus Riordan — Cornell IEB 2015

• Nucl. EM

22/30

SLIDE 25

VCS below ππ Threshold

Virtual Compton scattering has 6 independent generalized polarizabilities Scattering below threshold can also test χPT and DR formalisms past threshold Tests low energy non-perturbative dynamics

• f nucleon system

Similar work to be done for polarizabilities with full beam/target polarization states

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 26

Pion Production

Limited to ∆ resonance below 500 MeV πN coupling critical for chiral effective theories, isospin symmetry, etc. Couplings are some of the best studied properties, but still room for improvement (e.g. γn) New opportunities with high current (e.g. virtual photon tagging)

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 27

Charged Pion Production Near Threshold

π± at threshold sensitive to GA using chiral theories Assume dipole form with gA constrained Complementary to νn → µp scattering Both methods generally in agreement with latest χ corrections GA = gA 1 + Q2/M2

A

Bodek et al, JoP Conf 110 (2008) 082004 Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 28

Neutral Pion Production at Threshold

π0 production at threshold offers strong tests for χPT Coupling vanishes in the chiral limit and pπ → 0 Recent results with unpolarized and spin observables from JLab and MAMI and have agreement with low Q2 theories, but differences at high Q2

AT+L = a0 + b|p∗

π|2

b coefficient parameterizes p-wave multipoles

Hornidge et al. PRL 111, 062004 (MAMI) Chirapatpimol et al. PRL. 114, 192503 (JLab) Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 29

Nuclear Properties through EM Probes

Nuclear structure and low lying excited states have been done for decades Gives some of the best data we have in enumerating these states Possibility for studying some reaction channels (backwards) that have a photon in the final state

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 30

Nuclear Properties - Dipole Polarizabilities

Dipole polarizability offers constraints on symmetry energy density dependence

αD = c 2π2 σabs ω2 dω = 8π 9 B(E1) ω dω Ties into programs of neutron star studies, PREX/CREX Tamii EPJ A (2014) 50:28 208Pb Hashimoto arXiv:1503.08321 120Sn

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 31

Nuclear Properties - Dipole Polarizabilities

Dipole polarizability offers constraints on symmetry energy density dependence

αD = c 2π2 σabs ω2 dω = 8π 9 B(E1) ω dω Ties into programs of neutron star studies, PREX/CREX Tamii EPJ A (2014) 50:28 208Pb Hashimoto arXiv:1503.08321 120Sn

0.12 0.16 0.2 0.24 0.28 0.32

Rskin

208 (fm)

5 6 7 8 9 10

10-2D

208J (MeV fm3)

(b)

r=0.97 FSU NL3 DD-ME Skyrme SV SAMi TF

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 32

Nuclear Properties - Nuclear Resonance Fluorescense

NRF gives access to γA → γA processes Monochromatic beams from Compton backscattering can test very low lying < 10 MeV states to very high resolution Used at HIγS to identify state E and Jπ in 138Ba,

88Sr, 92Sr and 94Mo and

• thers, EM branching ratios,

etc.

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 33

Summary

Electromagnetic nuclear physics is an incredibly powerful and far-reaching tool for studying the strong nuclear force The Proton Radius Puzzle is one of the biggest problems in particle physics and is imperative to explore Many fundamental properties of the nucleon still remain to be measured to great precision, especially where polarization

• bservables are necessary and for the proton

New low energy, non-perturbative physics still remains an important area for exploration

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 34

BACKUP

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 35

Revisiting Kelly

Latest data fit with complete basis set:

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 1 2 3 4 5 µGEn/GMn Q2 [GeV2]

µGEn/GMn

0.2 0.4 0.6 0.8 1 1.2 2 4 6 8 10 12 GMn/(µGD) Q2 [GeV2]

GMn/(µGD)

0.2 0.4 0.6 0.8 1 1.2 2 4 6 8 10 12 µGEp/GMp Q2 [GeV2]

µGEp/GMp

0.2 0.4 0.6 0.8 1 1.2 5 10 15 20 25 30 35 40 GMp/(µGD) Q2 [GeV2]

GMp/(µGD)

• 0.2
• 0.15
• 0.1
• 0.05

0.05 0.1 0.15 0.2 0.25 0.3 0.5 1 1.5 2 2.5 3 r2 ρch [fm-1] r [fm]

Neutron charge λE=0

0.5 1 1.5 0.5 1 1.5 2 2.5 3 r2 ρmag [fm-1] r [fm]

Neutron mag λM=0

0.5 1 1.5 0.5 1 1.5 2 2.5 3 r2 ρch [fm-1] r [fm]

Proton charge λE=0

0.5 1 1.5 0.5 1 1.5 2 2.5 3 r2 ρmag [fm-1] r [fm]

Proton mag λM=0

Focusing more on high Q2 data uncertainty

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 36

Low Q2 Dirac/Pauli

u 1

/F

d 1

F

0.2 0.4 0.6

RCQM GPD Lattice VMD DSE Our Fit

]

2

[GeV

2

Q

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

u 2

F

u

• 1

κ /

d 2

F

d

• 1

κ

0.5 1.0 1.5

F p

1,2

= 2 3F u

1,2 − 1

3F d

1,2

F n

1,2

= −1 3F u

1,2 + 2

3F d

1,2

F1 predictions have pretty good consistency with data F2 is wildly off

Hard to accurately predict nucleon magnetic moments from first principles F2 contains quark “structure” - is zero (up to radiative corrections) for pointlike

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 37

Super Bigbite Program - Hall A

Motivation

Super Bigbite builds on large acceptance/moderate resolution experience Measures ratios to control systematics G p

E/G p M, G n M/G p M, G n E/G n M

Target Dipole Electron Arm Calorimeter Calorimeter Tracking Analyzer Coordinate Detector Proton Arm

. .

Segmented Hadron

• 2

p from Target (long distance) ToF and x/y Veto QE n/p separation Calorimeter Segmented Hadron Calorimeter Tracking PID

. .

Neutron/Proton Arm Electron Arm

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 38

FFs with 12 GeV CEBAF

High Q2 measurements of all four nucleon form factors planned

]

2

[GeV

2

Q

5 10 15 20 p M

/G

p E

G

p

µ

• 0.5

0.0 0.5 1.0 1.5

VMD - Bijker and Iachello VMD + Disp. Rel. - Hammer LFCBM - Miller (2002) DSE q(qq) - Roberts (2009) = 300 MeV Λ ,

2

)/Q

2

Λ /

2

(Q

2

ln ∝

1

/F

2

F

E12-07-109 (Hall A, SBS)

]

2

[GeV

2

Q

n M

/G

n E

G

n

µ

0.0 0.5 1.0

VMD - Bijker and Iachello VMD + Disp. Rel. - Hammer LFCBM - Miller (2002) DSE q(qq) - Roberts (2010) = 300 MeV Λ ,

2

)/ Q

2

Λ /

2

(Q

2

ln ∝

1

/F

2

F

• Schiavilla & Sick

20

d(e,e'd) T E12-09-016 (Hall A, SBS) E12-11-009, Hall C

2 4 6 8 10 12 14 16 18 20

]

2

[GeV

2

Q

5 10 15 20 D

G

p

µ /

p M

G

0.7 0.8 0.9 1.0 1.1 1.2

VMD - Bijker and Iachello VMD + Disp. Rel. - Hammer LFCBM - Miller (2002)

E12-07-108 (Hall A)

]

2

[GeV

2

Q

5 10 15 20 D

G

n

µ /

n M

G

0.6 0.8 1.0 1.2

VMD - Bijker and Iachello VMD + Disp. Rel. - Hammer LFCBM - Miller (2002)

E12-07-104 (Hall B) E12-09-019 (Hall A, SBS)

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 39

G p

E

Recoil polarimetry through two CH2 analyzers e− detected in ECal with coordinate detector Q2 up to 12 GeV2 75 µA on 40 cm target θh down to 17◦ Background rates up to 150 kHz/cm2 ECal radiation damage serious issue

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 40

High Q2 G n

E Experimental Layout

3He Target

BigBite w/ upgraded detectors e− Magnet Polarized 48D48 GEM Veto HCAL n

(Not to scale) 17m Path

Upgraded Bigbite detector stack for higher rates, better PID Hadron calorimeter at 17 m, need 0.5 ns ToF 48D48 deflects protons New addition of Cherenkov and GEMs for π− rejection and high rate tracking

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 41

Polarized 3He Target

Upgraded 3He cell allows for I = 8 → 60 µA, l = 40 → 55 cm Convection and metal cell ends allow for higher sustained P (∼ 60%)

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

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SLIDE 42

G n

M Setup

7 Q2 points ranging from 3.5 GeV2 to 13.5 GeV2 Setup similar to G n

E with LD2 target

BigBite w/ upgraded detectors e− LD 2 Target Magnet 48D48 GEM Veto HCAL n

(Not to scale) 17m Path

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

30/30

SLIDE 43

DSE/Fadeev q(qq) Calculations

Model based on QCD’s Dyson-Schwinger equations to describe dressed quark propagator Fadeev amplitudes describe three-quark states Few free parameters tuned to reproduce nucleon properties such as masses

]

2

[GeV

2

Q

n M

/G

n E

G

n

µ

0.0 0.2 0.4 0.6 0.8 DSE - Cloet (2010) Our Fit

Passchier, NIKHEF Herberg, MAMI Ostrick, MAMI Meyerhoff, MAMI Golak, MAMI Bermuth, MAMI Plaster, JLab Zhu, JLab Warren, JLab Glazier, MAMI Geis, BATES Riordan E02-013 Preliminary

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Bhagwat et. al. arXiv:nucl-th/0610080 Clo¨ et et. al. arXiv:nucl-th/0804.3118

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

30/30

SLIDE 44

Constituent Quark Light-Front Cloudy Bag Model

Construct model of 3 massive quarks or quark/diquark, include pion cloud:

π π qqq

]

2

[GeV

2

Q

2 4 6 8 10

p M

/G

p E

G

p

µ

0.0 0.5 1.0 Punjabi Gayou Puckett Reanalysis Puckett RCQM - G. Miller (2005)

• Cloet (2012)

π Diquark

G p

E suppression at higher Q2 due to inclusion of quark orbital

angular momentum Know only 1/3 of the spin of the proton is carried by the quark spins, reproduced with di-quark DOF

• G. Miller, Phys. Rev. C 66, 032201 (2002)

Seamus Riordan — Cornell IEB 2015

• Nucl. EM

30/30