STATUS OF DVCS ANALYSIS FROM E1-6 DATA · 2017. 3. 30. · 18000 20000 22000-t [GeV2] 0 0.2 0.4 0.6...

STATUS OF DVCS ANALYSIS FROM E1-6 DATA

Collaboration meeting 30.03.2017

A. Movsisyan, H. Avakian, S. Pisano

INFN-Ferrara

2

Introduction & Motivation

e e’

p p’

𝛄

Measurement of DVCS Cross Section,via detection of final state proton p’ and lepton e’.

Large statistics & broad kinematic coverage => large coverage of Φ acceptance.

Data collected in 2001-2002.Beam energy 5.754 GeV5cm long liquid hydrogen targetAverage beam polarization 70%

E1-6 experiment:epγep & epγ

spatial distributions of calculated photons

Aram Movsisyan, DPWG meeting 30.03.2017

3

Event Selection (ep (1𝛄) (2𝛄) sample)Primary selection - Events with exactly on 1 negative track with the id = 11,

1 positive track, any number of neutral clusters

Electron identification - EC fiducial cuts CC fiducial cuts DC fiducial cuts CC matching CC efficiency Requirements on Calo response

Proton identification - DC fiducial cuts Requirement on reconstructed ToF mass.

Requirements on event vertex

Photon identification - EC fiducial cuts Requirement on EC time. Spatial separation from charged tracks on EC. Minimum energy deposition in Calo.

Corrections Energy loss correction for electrons & protons Momentum & angle corrections for electrons Energy correction for photons


4

Exclusive pions (ep(2𝛄) sample)Exclusive Pion Selection: 1 electron, 1 proton & 2 photons

Kinematic requirements:

MC is normalized to Data with the scale factor for

Same scale factor is used to evaluate exclusive pion contribution in DVCS process: ep + ep𝛄 sample


W

2> 4 [GeV

2]

� t < 0.52 [GeV

2]

� 0.05 < M

2X(epX) < 0.09 [GeV

2]

Pele. > 0.7 [GeV ]

P⇡0> 2.5 [GeV ]

Sector(�1) = Sector(�2)

N

Data⇡0

0,1� (x,Q2,�t,�) =

N

Data⇡0

N

MC⇡0

N

MC0,1� (x,Q

2,�t,�)

NData⇡0

NMC⇡0

=9529

135217

5Aram Movsisyan, DPWG meeting 30.03.2017

Exclusive pions (ep(2𝛄) sample)Data - MC comparison exclusive 𝜋0:

]2 [GeV2Q1 2 3 4 50

50

100

150

200

250

300

350

400

Bjx0.1 0.2 0.3 0.4 0.5 0.60

50

100

150

200

250

300

[rad]φ2− 0 20

50100150200250300350400450

]2 [GeV2W4 6 8 100

50

100

150

200

250

300

350

]2-t [GeV0 0.2 0.4 0.60

50

100

150

200

250

]2(epX) [GeV2XM

0.05− 0 0.050

50

100

150

200

250


Exclusive photons (ep𝛄 sample)Data - MC comparison exclusive photons:

W 2 > 4 [GeV 2]

0.07 < �t < 0.52 [GeV 2]

|M2X(epX)| < 0.08 [GeV 2]

Pele. > 0.7 [GeV ]

t < tmin

✓�calc. > 2�

[GeV]γE0 1 2 3 4 5 60

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

Data - MC

[GeV]γE0 1 2 3 4 5 60

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

Data - MC

Expected photons within geometrical accepteanceData

0πExclusive DVCSMC sum

[GeV]caloE0.2 0.4 0.6 0.8 1 1.2

0.22

0.24

0.26

0.28

0.3

0.32

0.34

s.f - from e16 electrons

s.f - from CLAS-NOTE 2013-004, Simonyan, Stepanyan

s.f - from CLAS-NOTE 2013-004, Simonyan, Stepanyan

Sampling fraction


Exclusive photons (ep𝛄 sample)Data - MC comparison exclusive photons: (exclusive 𝜋0 , DVCS , MC sum )

]2 [GeV2Q1 2 3 4 50

200

400

600

800

1000

1200

Bj.x0.1 0.2 0.3 0.4 0.5 0.60

200

400

600

800

1000

[rad]φ2− 0 20

200

400

600

800

1000

1200

]2 [GeV2W4 6 8 100

200

400

600

800

1000

]2-t [GeV0 0.2 0.4 0.60

100

200

300

400

500

600

700

800

]2(epX) [GeV2XM

0.05− 0 0.050

200

400

600

800

1000

8

DVCS (ep + ep𝛄 sample)Exclusive Event Selection: 1 electron, 1 proton & 0 or 1 photon

Kinematic requirements:

xBj 0.15-0.17 0.17-0.19 0.19-0.21 0.21-0.23 0.23-0.25 0.25-0.27 0.27-0.29 0.29-0.32 0.32-0.35 0.35-0.40 0.40-0.55

-t 0.07-0.16 0.16-0.22 0.22-0.28 0.28-0.35 0.35-0.43 0.43-0.52

Statistics:

739647 events


W 2 > 4 [GeV 2]

0.07 < �t < 0.52 [GeV 2]

|M2X(epX)| < 0.08 [GeV 2]

Pele. > 0.7 [GeV ]

t < tmin

✓�calc. > 2� [rad]φ

3− 2− 1− 0 1 2 3

5000

10000

15000

20000° > 2.0 calc.γθ° > 2.2 calc.γθ° > 2.5 calc.γθ° > 2.8 calc.γθ° > 3.0 calc.γθ

9

DVCS (ep + ep𝛄 sample)Data - MC comparison (exclusive 𝜋0 , DVCS , MC sum):


[GeV]lep.P1 2 30

5000

10000

15000

20000

25000

30000

[deg]lep.θ20 30 40 50 600

2000400060008000

1000012000140001600018000

[deg]prot.θ0 20 40 600

2000400060008000

1000012000140001600018000200002200024000

[cm]prot.Zvtx10− 8− 6− 4− 2− 00

2000

4000

6000

8000

10000

12000

14000

[GeV] clac.γE2 3 4 50

5000

10000

15000

20000

25000

30000

[deg] clac.γθ0 10 20 300

10000

20000

30000

40000

50000

10



]2 [GeV2Q1 2 3 4 50

5000

10000

15000

20000

25000

Bj.x0.1 0.2 0.3 0.4 0.5 0.60

2000400060008000

10000120001400016000180002000022000

[rad]φ2− 0 20

2000400060008000

1000012000140001600018000200002200024000

]2 [GeV2W4 6 8 100

2000400060008000

10000120001400016000180002000022000

]2-t [GeV0 0.2 0.4 0.60

2000

4000

6000

8000

10000

12000

]2(epX) [GeV2XM

0.05− 0 0.0502000

400060008000

10000

12000140001600018000

11



[rad]φ2− 0 20

200

400

600

800

1000

[rad]φ2− 0 20

200400600800

10001200140016001800200022002400

[rad]φ2− 0 20

500

1000

1500

2000

2500

3000

[rad]φ2− 0 20

500

1000

1500

2000

2500

3000

[rad]φ2− 0 20

500

1000

1500

2000

2500

3000

[rad]φ2− 0 20

500

1000

1500

2000

2500

[rad]φ2− 0 20

500

1000

1500

2000

2500

[rad]φ2− 0 20

500

1000

1500

2000

2500

3000

[rad]φ2− 0 20

500

1000

1500

2000

2500

[rad]φ2− 0 20

500

1000

1500

2000

2500

[rad]φ2− 0 20

200

400

600

800

1000

1200

1400

12



]2-t [GeV0 0.2 0.4 0.60

200

400

600

800

1000

]2-t [GeV0 0.2 0.4 0.60

200400600800

1000120014001600180020002200

]2-t [GeV0 0.2 0.4 0.60

200400600800

10001200140016001800200022002400

]2-t [GeV0 0.2 0.4 0.60

200400600800

10001200140016001800200022002400

]2-t [GeV0 0.2 0.4 0.60

200400600800

1000

12001400160018002000

]2-t [GeV0 0.2 0.4 0.60

200

400

600

800

1000

1200

1400

1600

]2-t [GeV0 0.2 0.4 0.60

200

400

600

800

1000

1200

1400

]2-t [GeV0 0.2 0.4 0.60

200

400

600

800

1000

1200

1400

1600

1800

]2-t [GeV0 0.2 0.4 0.60

200

400

600

800

1000

1200

1400

]2-t [GeV0 0.2 0.4 0.60

200

400

600

800

1000

1200

1400

1600

]2-t [GeV0 0.2 0.4 0.60

200

400

600

800

1000

1200

[rad]φ0 1 2 3 4 5 6

1−10

1

10

= 1.49892Q = 0.1623Bjx

-t = 0.1105

bin_1 0.07 < -t < 0.16

[rad]φ0 1 2 3 4 5 6

1−10

1

10

= 1.49822Q = 0.1625Bjx

-t = 0.1869

bin_1 0.16 < -t < 0.22

[rad]φ0 1 2 3 4 5 6

1−10

1

10

= 1.49982Q = 0.1625Bjx

-t = 0.2485

bin_1 0.22 < -t < 0.28

[rad]φ0 1 2 3 4 5 6

1−10

1

10 = 1.50002Q = 0.1624Bjx

-t = 0.3135

bin_1 0.28 < -t < 0.35

[rad]φ0 1 2 3 4 5 6

1−10

1

10 = 1.49632Q = 0.1618Bjx

-t = 0.3898

bin_1 0.35 < -t < 0.43

[rad]φ0 1 2 3 4 5 6

1−10

1

10

bin_1 0.43 < -t < 0.52

= 1.49952Q = 0.1623Bjx

-t = 0.4722

bin_1 0.43 < -t < 0.52

13

DVCS (ep + ep𝛄 sample) X-section

BHKM 2016


Bin1

0.15 < xBj < 0.17

[rad]φ0 1 2 3 4 5 6

3−10

2−10

1−10

bin_21 0.07 < -t < 0.16

[rad]φ0 1 2 3 4 5 6

3−10

2−10

1−10

bin_21 0.16 < -t < 0.22

[rad]φ0 1 2 3 4 5 6

3−10

2−10

1−10

= 3.52782Q = 0.4115Bjx

-t = 0.2610

bin_21 0.22 < -t < 0.28

[rad]φ0 1 2 3 4 5 6

3−10

2−10

1−10

= 3.62162Q = 0.4233Bjx

-t = 0.3186

bin_21 0.28 < -t < 0.35

[rad]φ0 1 2 3 4 5 6

3−10

2−10

1−10

= 3.68952Q = 0.4349Bjx

-t = 0.3912

bin_21 0.35 < -t < 0.43

[rad]φ0 1 2 3 4 5 6

3−10

2−10

1−10

bin_21 0.43 < -t < 0.52

= 3.77102Q = 0.4483Bjx

-t = 0.4757

bin_21 0.43 < -t < 0.52

14

DVCS (ep + ep𝛄 sample) X-section

BHKM 2016


Bin21

0.40 < xBj < 0.55, ✓ < 34�

15

Comparison with Published Results

Figure 45: Kinematic coverage of the data and binning: Q2 (left) and ≠t (right) as a function ofxB. We defined 21 (Q2, xB) bins using limits in xB and ◊e, and 9 t bins.

xB ◊e (deg) % of the datasetbin 1 0.1 – 0.14 21 – 45 6.96%bin 2 0.14 – 0.17 21 – 25.5 5.48%bin 3 0.14 – 0.17 25.5 – 45 5.94%bin 4 0.17 – 0.2 21 – 25.5 6.48%bin 5 0.17 – 0.2 25.5 – 45 7.43%bin 6 0.2 – 0.23 21 – 27 7.89%bin 7 0.2 – 0.23 27 – 45 6.57%bin 8 0.23 – 0.26 21 – 27 6.69%bin 9 0.23 – 0.26 27 – 45 6.77%

bin 10 0.26 – 0.29 21 – 27 5.16%bin 11 0.26 – 0.29 27 – 45 5.90%bin 12 0.29 – 0.32 21 – 28 4.27%bin 13 0.29 – 0.32 28 – 45 4.19%bin 14 0.32 – 0.35 21 – 28 3.12%bin 15 0.32 – 0.35 28 – 45 3.20%bin 16 0.35 – 0.38 21 – 28 2.33%bin 17 0.35 – 0.38 28 – 45 2.50%bin 18 0.38 – 0.42 21 – 28 2.14%bin 19 0.38 – 0.42 28 – 45 2.40%bin 20 0.42 – 0.58 21 – 33 2.38%bin 21 0.42 – 0.58 33 – 45 2.20%

Table 4: 21 bins in the (Q2, xB) plane defined using xB and ◊e.

≠t (GeV2) % of the dataset0.09 – 0.13 11.57%0.13 – 0.18 12.91%0.18 – 0.23 11.21%0.23 – 0.3 12.13%0.3 – 0.39 11.38%0.39 – 0.52 11.19%0.52 – 0.72 10.84%0.72 – 1.1 10.74%1.1 – 2. 8.03%

Table 5: 9 bins in t.

53

Binning Used in Published analysis.

kinematic coverage of e16 data with binning Used in Published analysis.

✓ele > 21�

✓ele < 45�

Pele > 0.8 [GeV 2]

✓�calculated > 5�

Kinematic requirements to match the conditions of Published results


[rad]φ0 1 2 3 4 5 6

1−10

1

10

bin_5 0.07 < -t < 0.16

[rad]φ0 1 2 3 4 5 6

1−10

1

10

bin_5 0.16 < -t < 0.22

[rad]φ0 1 2 3 4 5 6

1−10

1

10

bin_5 0.22 < -t < 0.28

[rad]φ0 1 2 3 4 5 6

2−10

1−10

1

10bin_5 0.28 < -t < 0.35

[rad]φ0 1 2 3 4 5 6

2−10

1−10

1

10bin_5 0.35 < -t < 0.43

[rad]φ0 1 2 3 4 5 6

2−10

1−10

1

10bin_5 0.43 < -t < 0.52bin_5 0.43 < -t < 0.52

16

e16 e1-dvcs



Bin5

xBj � [0.17� 0.20]

✓ � [25.5� 45]

[rad]φ0 1 2 3 4 5 6

3−10

2−10

1−10

1bin_17 0.07 < -t < 0.16

[rad]φ0 1 2 3 4 5 6

3−10

2−10

1−10

1bin_17 0.16 < -t < 0.22

[rad]φ0 1 2 3 4 5 6

3−10

2−10

1−10

1bin_17 0.22 < -t < 0.28

[rad]φ0 1 2 3 4 5 6

3−10

2−10

1−10

1bin_17 0.28 < -t < 0.35

[rad]φ0 1 2 3 4 5 6

3−10

2−10

1−10

1bin_17 0.35 < -t < 0.43

[rad]φ0 1 2 3 4 5 6

3−10

2−10

1−10

1bin_17 0.43 < -t < 0.52bin_17 0.43 < -t < 0.52

17

e16 e1-dvcs



Bin17

xBj � [0.35� 0.38]

✓ � [28� 45]

18

a. Sufficiently good description of exclusive pion production by MC simulation allows to measure DVCS via detection of only electron and proton.b. Further improvement of Data-MC comparison can be obtained by improved particle ID and implementation of radiative corrections.c. Preliminary results are consistent with published CLAS data.

Thank you!

Conclusion & Outlook

a. Improve data-mc comparison.b. Radiative Corrections. c. Check sensitivity to background subtraction.d. Estimation of systematic uncertainties for the measurement of cross sections.


STATUS OF DVCS ANALYSIS FROM E1-6 DATA · 2017. 3. 30. · 18000 20000 22000-t [GeV2] 0 0.2 0.4 0.6...

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