gpdsgpds 3d structure functions at and -...
TRANSCRIPT
Workshop on hadron tomography at J-PARC and KEKB, January 6, 2017 @ KEK
3D structure functions
at and
Yoshiyuki Miyachi, Yamagata University
GPDsGPDs
Lepton-Nucleon scattering
experiments
Lepton-Nucleon scattering
experiments
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 2
Contents
● 3D Structure of the Nucleon● Generalized Parton Distributions
● GPDs in lepton-nucleon scattering● Deeply Virtual Compton Scattering
● Experiments: HERMES & COMPASS● DVCS results from COMPASS & HERMES● Summary
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 3
3D functions: Generalized Parton Distributions
Nucleon
Parton Parton
(x+ξ) P̄ (x−ξ) P̄
F (x , ξ ,t ,μ2)P P 't=(P'−P)
2
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 4
GPDs in lepton-nucleon scattering
l
l '
γ∗
N N '
A
l+N→ l '+N '+A
GPSs are studied with “Hard Exclusive Production” of A
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 5
Hard Exclusive Production and GPDs
q q'
P P’
t
Deeply Virtual Compton Scattering (DVCS):
Deeply Virtual Meson Production (DVMP):
q q'
P P’
t
e+N →e ' +N ' +γ
e+N →e ' +N ' +{ρ , π , ...}
Involved GPDs: clean reaction
vs Bethe-Heitler process
H , E , H , E
vector meson:pseudo-scalar meson:Meson amplitude involved
H , EH , E
⇔Exclusive DY: π−+ p→ n+ l−+l+
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 6
Experimental requirements
l
l '
γ∗
N N '
A
Q2>1GeV2
Hard scatteringHard scattering
Exclusive
Production
Exclusive
Production
・ recoil detection
・ missing mass
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 7
Experiments: HERMES and COMPASS
Beam
Target
Unpol. H/D
w/ recoil
detector
2006, 20072006, 2007
Unpol. H
w/ recoil
detector
2012,2016, 2017
2012,2016, 2017
w/ ECAL upgrade
L-pol. H/D
T-pol. H
w/o recoil
detector
2002~20052002~2005
1996~20001996~2000
Pol. NH3,
Pol. 6LiD
w/o recoil
detector
2002~20112002~2011
Pol. e+/e- in HERA e-ring
E = 27.6 GeV
e−/← , e−/→ ,e+ /← , e+ /→
Pol. μ+/μ-
E = 160~200 GeV
μ+ /← ,μ−/→@ 160 GeV
@DESY @CERN
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 8
Exclusive γ production at
e
e+ N → e '+ N + γe+ N → e '+ N + γ
Missing-mass spectrum
1996 ~ 2005: w/ Polarized H/D target
No detector for the recoil protonCut on missing-mass spectrum
Exc
lusi
ve
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 10
● Sub-detectors in 1 T Solenoid
● Photon Detector (PD)
– 3 Tungsten/Scintillator layers, π0, π/p
● Scintillation Fiber Tracker (SFT)
– 2 x (2 Parallel and 2 Stereo layers), momentum reconstruction and π/p
● Silicon Strip Detector (SSD)
– 2 layers of 16 double sided sensor, momentum reconstruction and π/p
● Unpol. H&D targets: (2006, 2007)
HERMES Recoil Detector ( 2006 ~ 2007)
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 14
+ kinematic constraint
e
Forward + recoil
Missing mass spectrum
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 15
COMPASS without a recoil detector
“Exclusive meson production”“Exclusive meson production”
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 16
COMPASS with a recoil detector (2012 Pilot Run, 2016 ~ 2017)
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 17
Exclusivity Check: Forward spectrometer vs CAMERA
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 18
Cross section of exclusive γ production
Bethe-Heitler (BH)
σDVCS≪σBH@HERMES
DVCS
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 19
Expected azimuthal distribution @ COMPASS
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 20
Exclusive photon azimuthal distribution(COMPASS 2012 Pilot Run) ~ 4 weeks
0.005< x<0.01 0.01<x<0.03
x>0.03● BH Monte Carlo normalization
based on integrated luminosity
● BH process dominant at small x
● π0 background contributing at large x
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 21
DVCS cross section t-slope(COMPASS 2012 Pilot Run)
x>0.03
● Subtract BH contribution● Subtract π0 background● Acceptance correction & Luminosity normalization
d σ (μ+←
)+d σ (μ−→
)∝
d σBH
+d σDVCS
+K s1Isin ϕ
d σDVCS
d|t|∼exp(−B|t|)
d σDVCS
d|t|∼exp(−B|t|)
Integrate over ϕ
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 22
Comparison with HERA results
⟨r⊥2 ⟩∼2B( xB)
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 23
0.01<x<0.03
σDVCS≪σBH@HERMES
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 26
Differential cross section
d σ∝
Unpol. target
Beam helicityBeam helicityBeam ChargeBeam Charge
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 27
Cross section asymmetries and GPDs
ALU
PRL 87 (2001) 182001PRL 87 (2001) 182001
AC
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 28
@HERMES, COMPASS@HERMES, COMPASS
Negligible
Sum of quark flavors
Compton form factorsCompton form factors NPB629 (2002) 323-392
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 31
with a transversely polarized target
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 32
DVCS with a transversely polarized target
UT → GPD EUT → GPD E
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 33
Experimental requirements
l
l '
γ∗
N N '
A
Q2>1GeV2Hard scatteringHard scattering Exclusive
Production
Exclusive
Production
・ recoil detection
・ missing energy
Polarized beam
Anti-lepton beam
Polarized beam
Anti-lepton beam
Transverse pol. for ETransverse pol. for ENot available yet
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 34
Extracted overall asymmetries @ HERMES
Beam Charge Asymmetries
Beam Spin Asymmetries
Target Spin Asymmetries
Double Spin Asymmetries
Target Spin Asymmetries
Double Spin Asymmetries
T-p
ol.
targ
etL-
pol.
targ
et
H
GPD
E
~H
PRL 87 (2001) 182001PRD 75 (2007) 011103JHEP 11 (2009) 083JHEP 07 (2012)032JHEP 10 (2012) 042NPB 829 (2010) 1
PRL 87 (2001) 182001PRD 75 (2007) 011103JHEP 11 (2009) 083JHEP 07 (2012)032JHEP 10 (2012) 042NPB 829 (2010) 1
JHEP 06 (2008) 066PLB 704 (2011) 15JHEP 06 (2008) 066PLB 704 (2011) 15
JHEP 06 (2010) 019NPB 842 (2011) 265JHEP 06 (2010) 019NPB 842 (2011) 265
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 36
Beam charge asymmetry
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 37
Beam spin asymmetry
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 38
Beam Spin Asymmetry with Recoil Detector at HERMES
JHEP 10 (2012) 042JHEP 10 (2012) 042
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 40
DVCS with T-pol. H target HERMES,
JHEP06 (2008) 066
ACcos
∝ℜ[ F H ]
AUT , DVCSsin− S
∝ℑ[H E ∗−E H ∗
E H ∗− H E ∗
]
AUT , Isin− S
∝−AUT ,Isin −Scos
∝ℑ[ F1E −F2H ]
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 41
Extracted overall asymmetries @ HERMES
Beam Charge Asymmetries
Beam Spin Asymmetries
Target Spin Asymmetries
Double Spin Asymmetries
Target Spin Asymmetries
Double Spin Asymmetries
T-p
ol.
targ
etL-
pol.
targ
et
H
GPD
E
~H
PRL 87 (2001) 182001PRD 75 (2007) 011103JHEP 11 (2009) 083JHEP 07 (2012)032JHEP 10 (2012) 042NPB 829 (2010) 1
PRL 87 (2001) 182001PRD 75 (2007) 011103JHEP 11 (2009) 083JHEP 07 (2012)032JHEP 10 (2012) 042NPB 829 (2010) 1
JHEP 06 (2008) 066PLB 704 (2011) 15JHEP 06 (2008) 066PLB 704 (2011) 15
JHEP 06 (2010) 019NPB 842 (2011) 265JHEP 06 (2010) 019NPB 842 (2011) 265
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 42
COMPASS 2016 ~ 2017(2 × 6 months)
0.01<x<0.03
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 43
Expected beam charge spin asymmetries
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 44
Summary
● “Hard Exclusive Production in lepton-nucleon scattering” is a tool to study GPDs.
● Deeply Virtual Compton Scattering● Hard exclusive meson production Exclusive DY⇔
● DVCS @ HERMES● 27.6 GeV polarized e-/e+
– Combine analysis of “Charge” & “Spin”● L-Pol. H/D targets, T-Pol. H target (w/o the recoil detector)
● Unpol. H/D targets (w/ the recoil detector)● Various azimuthal amplitudes were extracted
2017/01/06@KEK Hadron Tomography at J-PARC and KEKB 45
Summary
● DVCS @ COMPASS● 160 GeV μ-/μ+● Unpol. H target with the recoil detector
● 2012 Pilot Run
● t-slope of σDVCS
extracted
● 2016 Run successfully finished + 2017 Run (2 × 6 months)● GPD H via Interference term
● >2018: DVCS with transv. pol. target and recoil detector● GPD E● Future addendum to COMPASS-II proposal