Sub-Nucleon Physics Programme

1
Sub-Nucleon Physics Programme

• Current Status Outlook for Hadron Physics
• D G Ireland

2
From quarks to nuclei

• Selected Topics
• Excitation of the Nucleon
• Nucleon Structure
• Exotics and Confinement

3
Studying the Strong Force
Nucleon structure and dynamics
Static properties and phenomenology
QCD
QCD-inspired models
4
Current effort
5
Excitation of the Nucleon
N
6
Resonance hunting
Total Cross-sections differential
cross-sections Partial Wave Analysis ...

• ??????????P33
• N(1440)P11
• N(1520)D13
• N(1535)S11
• ?(1600)P33

Cross section
0.5 1.0
1.5
E? (GeV)
Mostly done with Pion-N scattering or
photoproduction Missing resonances may decay
through other channels
7
Meson Photoproduction Cross sections
8
Meson Photoproduction
9
CLAS
10
CLAS Results CMU Analysis
11
CLAS Results CMU Analysis
12
(No Transcript)
13
The FROzen Spin Target
14
(No Transcript)
15
Nucleon Structure
16
Generalised Parton Distributions
Formfactor
PDF
GPD
17
Super BigBite Jlab Hall A
18
(No Transcript)
19
The HERMES Spectrometer
27.6 GeV e/e-
Recoil Detector, 2005 -2007
20
Angular Momentum Constraints
Kinematic dependence of single observables does
not sufficiently constrain models Combination of
different observables and different experiments
needed HERMES and Jlab complement each other
ideally
arXiv 0802.2499
21
CLAS12 (Jlab upgrade)
22
Exotics and Confinement
Lattice Gauge Theory
The Flux Tube Model
Quark Models ? Linear qq potential
Confirmation of idea
23
Gluonic Excitations
Quantum number rules for quark-antiquark pair-
JPC 0 0 1 1 2
Allowed combinations?
JPC 0 0 1 2
Not-allowed exotic?
Combine with S1 for quarks to get
Flux tube model 1st excited state of flux tube
has J1
JPC 0- 0- 1- 1- 2- 2-
exotic
Exotic mesons are not generated when S0
24
(No Transcript)
25
Jlab 12GeV Upgrade
26
The GlueX Project at Jlab
27
(No Transcript)
28
(No Transcript)
29
The PANDA detector
30
Mass Range
31
(No Transcript)
32
(No Transcript)
33
Current Status

• Excitation of the nucleon
• Advance to goal of complete measurement many
  observables already measured
• Use of spin-polarised targets started
• Nucleon structure
• Major programme of measurement started at HERMES
• Will continue at CLAS12 (Jlab)
• Exotics and Confinement
• Pilot measurements started
• GluEx and PANDA to address the issue

34
Outlook

• Complete nucleon resonance programme (MAMI,
  CLAS,)
• Continue nucleon structure studies (HERMES,
  CLAS12,)
• Develop searches for exotics (CLAS, GluEx,
  PANDA,)

35
(No Transcript)
36
(No Transcript)
37
(No Transcript)
38
Sivers Effect

• Motion of quarks induces emission in a preferred
  direction
• Leading hadron carries information on struck
  quark
• Measurement requires large beam energies
• Pioneered at HERMES, precision studies to follow
  at CLAS 12

39
MAinz MIcrotron

• up to 1.5 GeV/c polarised electron beam
• A1 Electron scattering off nucleons and nuclei
• A2 photoexcitations of nucleons and nuclei with
  polarised photons
• Glasgow tagger and goniometer essential
  ingredients to facility

40
Crystal Ball at MAMI A2

• High rate, polarised, tagged photon beam up to
  1.4 GeV with 2 MeV resolution (and microscope)
• Liquid H2/D2, 208Pb, 40Ca, 16O, 12C and other
  nuclear targets
• Two EM calorimeters for full solid angle coverage
• MWPC PID for tracking and ID of charged
  particles
• Ideal for high precision / low cross section
  measurements

41
Magnetic Moments of Resonances