Collins effect ( Sin( φ h + φ S ) ) Access to transversity Artru model
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• Collins effect ( Sin(φ h + φ S ) ) – Access to transversity • Artru model •Based on LUND fragmentation picture. Neutron (e,e’ Neutron (e,e’π ± ) Target Single-Spin Asymmetry in ) Target Single-Spin Asymmetry in Semi-inclusive DIS on a Transversely Polarized Semi-inclusive DIS on a Transversely Polarized 3 He Target He Target Kalyan Allada, Chiranjib Dutta, Mitra Shabestari, Xin Qian On the behalf of Transversity Collaboration Two experiments with the highest scientific rate: Nucleon Structure Nucleon Structure • Nucleon anomalous magnetic moment (Stern, Nobel Prize 1943) • Electromagnetic form factor from electron scattering (Hofstadter, Nobel Prize 1961) • Deep-in-elastic scattering, quark underlying structure of the nucleon (Freedman, Kendell, Taylor, Nobel Prize 1990) Understanding the underlying nucleon structure (Spin, flavor, charge, current distribution) from quantum chromodynamics (confinement region) is essential. Electronuclear Scattering Electronuclear Scattering ------ A powerful tool to study nuclear structure Inclusive: (the main tool) detecting electron only Semi-inclusive: (providing additional information) detecting electron and one of the hadrons coincidently Spectrum: What is Semi-Inclusive What is Semi-Inclusive Deep Inelastic Scattering Deep Inelastic Scattering (SIDIS) (SIDIS) • E’ is the energy of scattered electron •θ e is the scattering angle • ν =E-E’ is the energy transfer. •k T : quark transverse momentum Characteristics of Characteristics of Transversity Transversity • Some characteristics of transversity : –h 1T = g 1L for non-relativistic quarks •In non-relativistic case, boosts and rotations commute. – Important inequalities: |h 1T q | ≤ f 1 q ; |h 1T q | ≤ (f 1 q + g 1L q )/2. –h 1T and gluons do not mix – Q 2 -evolution for h 1T and g 1L are different – Chiral-odd → •not accessible in inclusive DIS N q q N Helicit y state - + • It takes two Chiral-odd objects to measure transversity – Drell-Yan (Doubly transversely polarized p-p collision) – Semi-inclusive DIS Chiral-odd distributions function (transversity) Chiral-odd fragmentation function (Collins function) - Detector system & Detector system & 3 3 He Target He Target HRS HALL-A 3 He Target Projections Projections HRS Collins and Sivers Asymmetry Parton distribution Function (PDF) Fragmentation function (FF) DXs~PDF*FF The kinematics and coordinate The kinematics and coordinate DIS: Q 2 (1/λ) and ν is large, but x is finite. Scattering plane Beam direction Into the page • Sivers effect ( Sin(φ h - φ S ) ) – A new type of PDF, T-odd, depends on intrinsically quark transverse momentum quark orbital momentum Asymmetry in Semi-Inclusive DIS Asymmetry in Semi-Inclusive DIS with polarized target with polarized target 40-cm long Rb-K spin-exchange hybrid cell at 10 atm . ~42% target polarization with spin-flip frequency of 20 minutes. A third set of Helmholtz coil will be added together with the laser optics to allow vertical polarization of the 3 He target. Target Polarimetry NMR and EPR will be used to measure the target polarization. First direct data on neutron A UT At high-x Clear separation of Collins and Sivers effect. Statistical uncertainty dominates. Kinematics comparable to the HERMES experiment. Hall-A Setup Beam - 6Gev, 15 microA electron beam Target Electron detection - BigBite spectrometer, solid angle = 64msr, at 30 0 Charged pion detection - Hall-A High Resolution Spectrometer, at -16 0 Transversity, business just started. HALL A: 29 days HERMES: 3 years COMPASS: 1 year Well Known, since first measurement at 70s. Reasonable Known with 20 years effort. A
description
Neutron (e,e ’ π ± ) Target Single-Spin Asymmetry in Semi-inclusive DIS on a Transversely Polarized 3 He Target . -. Kalyan Allada, Chiranjib Dutta, Mitra Shabestari, Xin Qian On the behalf of Transversity Collaboration Two experiments with the highest scientific rate: . A. - PowerPoint PPT Presentation
Transcript of Collins effect ( Sin( φ h + φ S ) ) Access to transversity Artru model
• Collins effect ( Sin(φh+ φS) )– Access to transversity
• Artru model• Based on LUND
fragmentation picture.
Neutron (e,e’Neutron (e,e’ππ±±) Target Single-Spin Asymmetry in ) Target Single-Spin Asymmetry in Semi-inclusive DIS on a Transversely Polarized Semi-inclusive DIS on a Transversely Polarized 33He He
Target Target Kalyan Allada, Chiranjib Dutta, Mitra Shabestari, Xin
QianOn the behalf of Transversity Collaboration
Two experiments with the highest scientific rate: Nucleon StructureNucleon Structure
• Nucleon anomalous magnetic moment (Stern, Nobel Prize 1943)
• Electromagnetic form factor from electron scattering (Hofstadter, Nobel Prize 1961)
• Deep-in-elastic scattering, quark underlying structure of the nucleon (Freedman, Kendell, Taylor, Nobel Prize 1990)
Understanding the underlying nucleon structure (Spin, flavor, charge, current distribution)from quantum chromodynamics (confinement region) is essential.
Electronuclear ScatteringElectronuclear Scattering------ A powerful tool to study nuclear structure
Inclusive: (the main tool)
detecting electron only Semi-inclusive: (providing additional information) detecting electron and one of the hadrons coincidently
Spectrum:
What is Semi-Inclusive Deep What is Semi-Inclusive Deep Inelastic Scattering (SIDIS)Inelastic Scattering (SIDIS)
• E’ is the energy of scattered electron
• θe is the scattering angle
• ν =E-E’ is the energy transfer.
• kT: quark transverse momentum
Characteristics of TransversityCharacteristics of Transversity
• Some characteristics of transversity :– h1T = g1L for non-relativistic quarks
• In non-relativistic case, boosts and rotations commute.
– Important inequalities: |h1Tq| ≤ f1
q ; |h1Tq| ≤ (f1
q + g1Lq )/2.
– h1T and gluons do not mix
– Q2-evolution for h1T and g1L are different– Chiral-odd →
• not accessible in inclusive DIS
N
q q
N
Helicity state
- +
• It takes two Chiral-odd objects to measure transversity– Drell-Yan (Doubly transversely polarized p-p collision)– Semi-inclusive DIS
Chiral-odd distributions function (transversity)Chiral-odd fragmentation function (Collins function)
-
Detector system & Detector system & 33He TargetHe Target
HRS
HALL-A 3He Target
ProjectionsProjections
HRS
Collins and Sivers Asymmetry
Parton distribution Function (PDF)
Fragmentationfunction (FF)DXs~PDF*FF
The kinematics and coordinateThe kinematics and coordinate
DIS: Q2 (1/λ) and ν is large, but x is finite.
Scatteringplane
Beam direction
Into the page
• Sivers effect ( Sin(φh- φS) )– A new type of PDF, T-odd, depends on intrinsically
quark transverse momentum quark orbital momentum
Asymmetry in Semi-Inclusive DIS with polarized Asymmetry in Semi-Inclusive DIS with polarized targettarget
40-cm long Rb-K spin-exchange hybrid cell at 10 atm .
~42% target polarization with spin-flip frequency of 20 minutes.
A third set of Helmholtz coil will be added together with the laser optics to allow vertical polarization of the 3He target.
Target Polarimetry
NMR and EPR will be used to measure the target polarization.
First direct data on neutron AUT
At high-x
Clear separation of Collins and Sivers effect.
Statistical uncertainty dominates.
Kinematics comparable to the HERMES experiment.
Hall-A Setup
Beam
- 6Gev, 15 microA electron beam
Target
Electron detection - BigBite spectrometer, solid angle = 64msr, at 300
Charged pion detection
- Hall-A High Resolution Spectrometer, at -160
Transversity, business just started.
HALL A: 29 days
HERMES: 3 years
COMPASS: 1 year
Well Known, since first measurement at 70s.
Reasonable Known with 20 years effort.
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