u-channel Omega Meson Production from the Fpi-2 Experiment

Transcription

1 u-channel Omega Meson Production from the Fi- Exeriment Student: Bill (Wenliang Li Suervisor: Garth Huber Hall C Worksho. January, 017. Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada.

2 Outlook from last year and Outline Outline Brief introduction to the exeriment Theoretical Justification Preliminary Exerimental Results Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada.

3 Fi- E Exeriment Fi- (E Sokeserson: Garth Huber, Henk Blok Q =.45 GeV 003 Standard HMS and SOS (e configuration Electric form factor of charged π through exclusive π roduction Low ϵ π + Low ϵ ω Primary reaction for Fi- (e, e π + n Coincidence time ex missing mass In addition, we have for free (e,e ω High ϵ π + High ϵ ω Kinematics coverage W=.1 GeV, Q =1.6 and.45 GeV Two ϵ settings for each Q Coincidence time ex missing mass 3 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada.

4 t-channel π vs u-channel ω 0 Production n e e (e, e π + n π + ω e e HMS along the q-vector ( γ* π+ is arallel to γ* (Forward ω is anti-arallel to γ* (Backward (e, e ω Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 4

5 Exclusive ω Electro-Production Data Fi- Hall C 004 Closest data set to ours is the Hall B Morand data Q GeV W GeV x -t GeV HERMES (Airaetian et al., 014 > < 0. DESY (Joos et al., < 0.5 Zeus (Breitweg et al., ~0.01 < 0.6 Cornell (Cassel et al., <1 JLab Hall C (Ambrozewicz et al., 004 ~0.5 ~ JLab Hall C (Dalton et al., >4.0 JLab Hall B (Morand et al., <.7 JLab Fi- ( , , , 4.74 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 5

6 Regge Trajectory Model by JM Laget W (GeV x Q (GeV -t (GeV -u (GeV Hall B <.7 > 1.68 Hall B Fi- Fi Real γ Virtual γ Hard Scattering Mechanism schematics Fi kinematics Wenliang Li, Det. of Physics, Univ. J. M. of Regina, Laget, Phys. Regina, Rev. SK D 70, S4S0A, 004 Canada. t-channel Forward u-channel Backward 6

7 Further motivation: Transition Distribution Amlitude (TDA TDA backward angle analog of GPD Interaction of Interest: u-channel seudocalar and vector π and roduction Extension of the TDA model to describe the backwards vector meson roduction TDA Factorization Made two Predictions (B. Pire, K. Semenov, L. Szymanowski, Phys. Rev. D, 91, (015. The dominance of the transverse olarization of the virtual hoton resulting in the suression of the longitudinal cross section by at least 1/Q : σ T > σ L. (We can validate this! The Characteristic 1/Q 8 -scaling behaviour of the σ T for a fixed Bjorken x (We can t test this. Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 7

8 Analysis: Cuts Alied and Efficiency Study Q =1.60 hsytar Q =.45 Aerogel Cut Low ε High ε Real Random Random u-distribution Cut 1 3 Cuts Alied Detector accetance cuts Cointime-hsbeta cuts (Hsbeta=0 events included PID Cuts Diamond cuts u cut Efficiency Results Tracking Efficiency Correction ( <3% Proton Scattering Efficiency (4.7% Aerogel Cut Efficiency (7.3% Other standard efficiencies Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 8

9 Analysis: e+h Elastic Cross-Section Cut Elastic Sim Elastic Data Dummy Data Coincidence e+h elastic Fitted Result: ± Blue line: fitted average Pink Shade: fitted error band Dotted Line: oint-to-oint error band Extracted cross section is consistent with Bosted, AMT (Arrington, Melnitchouk, Tjon Phys. Rev. C 76, (007 and Brash emirical e- elastic cross section arameters. ±.0% (oint to oint error from Hee will be the included to the final Omega analysis systematics Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 9

10 Rosenbluth Searation Method Virtual-hoton olarization: ( Ee Ee' Q e' 1 tan Q 1 d d L dt d d d td dt dt dt dt Rosenbluth Searation method requires LT TT 1 co s co s Searate measurements are taken at different ε (virtual hoton olarization All Lorentz invariant hysics quantities such as Q, W, t, u, remain constant Beam energy, scattered e angle and virtual hoton angle will change as the result, thus event rates are dramatically different Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 10

11 Missing Mass Distribution ω (78 MeV Polynomial + ω Simulation Right η (947 η (547 ρ (770 + π Center Most Challenging Issue: Background Subtraction! Omega is not always in the center Four sets of Monte-Carlo is used fit the data ω + ρ + Phase-sace + η or η Left Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 11

12 Iterative Procedure (Recie to A Full LT Searation Imrove φ coverage by taking data at multile HMS angles, -3 o <θ q <+3 o. θ q =0 θ q =-3 θ q =+3 -u=0.0 -u=0.3 -u=0.5 Background Subtraction 3 u bins 8 hi bins Searated X-section Unsearated X-section For each HMS setting, form ratio: R = Y Ex Y ρ sim Y Xsace sim Y η sim Y ω sim Combine ratios for settings together, roagating errors accordingly. d dtd EXP R d dtd SIMC Extract T, L, LT, TT via simultaneous fit Emirical Model d d T d L d LT d TT 1 cos cos dtd dt dt dt dt Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 1

13 Missing Mass Distribution Background Extraction Data (blue oint Xsace Sim (green ρ Sim (light blue ω Sim (red η or η (black Simulation Sum (ink Omega Background Sum Zero= Data Omega- Bg Fitting Limits (red dashed line: Not fixed, fit 95% data distribution R = Y Ex Y ρ sim Y Xsace sim Y η sim Y ω sim Integration Limits (blue dashed line: Fixed for all u-hi bins! Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. Bin Exclusion criteria: Radiative tail exceeds 50% total ω sim Less that 100 counts 13

14 Background Extraction and Check Worse examle Missmass edge examle Sum of the data from each bin sum of the Omega sim from each bin Reconstructed Missing Energy For the worse examle Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 14

15 Yield Ratio and Simulated Cross-Section d d T d L d d dtd dt dt dt dt LT TT 1 cos cos Model Cross Section d dtd EXP R d dtd SIMC 0<u<0.10 (t~ <u<0.17 (t~4 0.17<u<0.3 (t~3.8 R=1 Ex/Sim Yield Ratio Q =1.6, Low ε=0.33 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 15

16 Unsearated Cross Section (Money Plot d dtd d d T d L d d dtd dt dt dt dt 0<u<0.10 (t~4.1 High ε=0.59 LT TT 1 cos cos 0.10<u<0.17 (t~4 0.17<u<0.3 (t~3.8 Q =1.60 Low ε=0.33 Anti-arallel Kinetics u-bin 0<u<0.19 (t~4.9 ϕ 0.19<u<0.30 (t~ <u<0.50 (t~4.5 d dtd High ε=0.55 Low ε=0.7 Q =.45 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. ϕ 16

17 Searated Cross Section Q =1.6 Q =1.6 Q =.45 Q =.45 Q =1.6 Q =1.6 Q =.45 Q =.45 (Black data oints (Blue dot Prev. Model (Red Fit Observations: Q =1.60 Q =.45 SigT dominate SigL at.45 at u~0: validated the TDA rediction (σ T > σ L for Q =.45 SigT behave differently at different Q. LT and TT are small Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 17

18 Remaining Work Reconstruct the focal lane arameters Systematics studies: Integration limit deendence Fitting limit deendence Demonstrate stability of the searated cross section A rebin analysis is on the way Comare to the redicted result by TDA model Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 18

19 Future Backward Meson Production Oortunities e Potential LOI (018: Backward π 0 roduction at Hall C. Other extreme forward angle hysics rogram Fi 1 exeriment (for free η, η, ω, ϕ(sതs, ρ X e (e, e X Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 19

20 Thanks You Secial thanks to Dave Gaskell and Henk Blok. Fantastic quality NTules analyzed by Tanja Horn. Gratitude to my graduate student colleagues and my family (secially my wife Noemi Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 0

21 Fi- E Exeriment Fi- (E exeriment: nd ion form factor exeriment 001 Sokeserson: Garth Huber, Henk Blok, Dave Mack Standard HMS and SOS (e configuration. Using exclusive charged π roduction to determine the electric form factor from the L/T searated differential cross section Primary reaction for Fi- (e, e π + n and n(e, e π - Through standard t-channel In addition, we have (for free (e,e ω Through u-channel Kinematics coverage Same of Fi- π + data Same data set: W=.1 GeV, Q =1.6 and.45 GeV Two ϵ settings for each Q π + coverage ω coverage : uu d d ω (78: J P = 1, I G = 0, M ω =78 MeV. Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 1

22 High -t Data from CLAS Hall B (005 Circ: σ TT Solid: σ LT Curve: Regge Model Calculation Secialty: Highest -t (low u ω meson roduction data Excitement: Observation: Q indeendent cross section at high -t Possible interoeration: Virtual hoton is more likely to coule to a oint-like object as t increases. Integrated over -.7 GeV < t < t 0 where t 0 ranges to GeV, as x ranges between 0.03 to 0.61 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada.

23 Pseudoscalar meson (J P = 0 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 3

24 Vector meson (J P = 1 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 4

25 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 5 target (Fi xed ( B m Q W Q Q W Q x Q W q W q q W s q Q q Q x m m Q t u s m m m m t u s Equations

26 Regge Trajectory Based Model by JML L. Morand, Ph.D. Thesis, University of Paris 003 J. M. Laget, Phys. Rev. D 70, Published 8 Setember 004 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 6

27 Hall B ublic age Hall B ublic age: htts:// Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 7

28 Exclusive ω electro-roduction data Hall B data: Wide coverage Highest t Fi- Hall C 004 Q GeV W GeV x -t GeV HERMES (Airaetian et al., 014 > < 0. DESY (Joos et al., < 0.5 Zeus (Breitweg et al., ~0.01 < 0.6 Cornell (Cassel et al., <1 JLab Hall C (Ambrozewicz et al., 004 ~0.5 ~ JLab Hall B (Morand et al., <.7 JLab Fi- (017? 1.6, , , 4.74 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 8

29 High t Data from CLAS Hall B (005 Morand et al., Eur. Phys. J. A 4, 445 (005. e Beam (78MeV e e 0 Hall B Exeriment e1-6 Oct 001 Jan 00 Beam energy: GeV Kinematic coverage: W : GeV Q: GeV -t : <.7 GeV x: Event selection: e e X Reconstructed e - X missing mass consistent with the ω mass. Q.5GeV 3.1 Q 3.6GeV 0.34 x x Missing mass reconstruction e - X Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. Data ublished in 005: Morand et al., Eur. Phys. J. A 4, 445 (005. 9

30 Regge Trajectory Model by JM Laget Real γ Virtual γ Real γ Virtual γ No data yet, Fi kinematics Q =.54, W=.1, -t=4.7 J. M. Laget, Phys. Rev. D 70, 004 The determination of the deendency against the momentum transfer t of the longitudinal and the transverse arts of the various meson electroroduction channels must be actively ursued at JLab energy range It would be great if JML could make a calculation similar for Fi- kinematics Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 30

31 d σ/dtdφ (μb/gev Extract Resonse Functions through Iterative Procedure Imrove φ coverage by taking data at multile π (HMS angles, -4 o <θ πq <4 o. θ πq =0 θ πq =+4 -t=0.1 -t=0.3 For each π HMS setting, form ratio: YEXP R YSIMC Combine ratios for π settings together, roagating errors accordingly. Q =1.60 π + Extract via simultaneous fit of L,T,LT,TT d dtd EXP Y Y EXP SIMC d dtd SIMC d d td d dt d dt d dt d dt φ πq (deg L T LT TT 1 co s co s Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 31

32 High -t Data from CLAS Hall B (005 L. Morand et al., Eur. Phys. J. A 4, 445 (005. t=-1.45 t=-.30 Hall B & Fi- kinematics comarison W (GeV x Q (GeV -t (GeV -u (GeV Hall B <.7 > 1.68 Fi t=-0.55 Hall B Fi- t=-1.45 t=-.30 Excitement: Observation: Q indeendent cross section at high -t Possible interoeration: Virtual hoton is more likely to coule to a oint-like object as -t increases. Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. Hard Scattering Mechanism schematics 3

33 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. Exeriment was carried out at Hall C, Jefferson Lab 004 HMS (recoiled roton along the q-vector ( γ* ω is anti-arallel to γ* t: Comaring before and after interaction u: Comaring before interaction with ω after interaction u-channel interaction when u~0 Backward Angle (u-channel ω Production 33 e e (e, e ω ω ( ( ( ( 1 * q q 1 ω ( ( ( ( ( ( q u q t q s

34 Analysis: Efficiency Study Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 34

35 Missing Mass Distribution Background Extraction Integration limits and fitting limits Exclusion criteria Exclude the radiative only omega bins Exclude the low statistics bins Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 35

36 Background Subtraction Checking Reconstructed the E_m distribution, with missing mass scale factor Sum of the data from each bin sum of the Omega sim from each bin Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 36

37 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada ( ( ( ( ( ( q u q t q s ( ( ( ( 1 * q Christian Weiss: A roton being knocked out of a roton u-channel ω 0 Production In fixed target exeriment t: Comaring before and after interaction u: Comaring before interaction with ω after interaction u-channel interaction when u~0 High t corresonds to low u u min = 0

38 Kinematics Table Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 38

39 High -t Data from CLAS Hall B (005 L. Morand et al., Eur. Phys. J. A 4, 445 (005. t=-1.45 t=-.30 Hall B & Fi- kinematics comarison W (GeV x Q (GeV -t (GeV -u (GeV Hall B <.7 > 1.68 Fi t=-0.55 Hall B Fi- t=-1.45 t=-.30 Excitement: Observation: Q indeendent cross section at high -t Possible interoeration: Virtual hoton is more likely to coule to a oint-like object as -t increases. Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. Hard Scattering Mechanism schematics 39

40 TDA Prediction (Private Communication Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 40

41 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 41