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

Transcription

1 u-channel Omega Meson Production from the Fi- Exeriment Bill (Wenliang) Li Hall C Worksho. January, 015.

2 Outline Where the data come from Theoretical justification Plan for data analysis Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada.

3 Fi- E Exeriment Fi- (E01-004) 003 Sokeserson: Garth Huber, Henk Blok, Dave Mack 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 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 3

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

5 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

6 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., 1977) < 0.5 Zeus (Breitweg et al., 000) ~0.01 < 0.6 Cornell (Cassel et al., 1981) <1 JLab Hall C (Ambrozewicz et al., 004) ~0.5 ~ JLab Hall B (Morand et al., 005) <.7 JLab Fi- (017?) 1.6, , , 4.74 Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 6

7 High t Data from CLAS Hall B (005) Morand et al., Eur. Phys. J. A 4, 445 (005). e Beam (78 MeV ) 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 3.6 GeV 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). 7

8 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 8

9 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. 9

10 Lansberg, et al., Phys. Rev. D 77, (008) Further motivation: Transition Distribution Amlitude (TDA) TDA backward angle analog of GPD Interaction of Interest: u-channel π roduction Extension of the TDA model to describe the backwards vector meson roduction Publication: Lansberg, et al., Phys. Rev. D 77, (008) Pasquini, B. et al. Phys.Rev. D80 (009) Lansberg, J.P. et al. arxiv: [he-h] CPHT-PC Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 10

11 Data Analysis Plan ω ρ + π Data analysis is similar to that used for the Fi- Physics Background Removal ρ Phase sace of π roduction Method: BG simulation or fitting a olynomial? Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 11

12 Rosenbluth Searation Method V irtu a l- h o to n o la riz a tio n : e e ' e ' ( E E ) Q 1 ta n Q 1 d d L d T d d dtd dt dt dt dt Rosenbluth Searation method requires LT TT 1 cos cos 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. 1

13 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: R Y Y SIMC Combine ratios for π settings together, roagating errors accordingly. EXP 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 d L T LT TT φ πq (deg) 1 cos cos dtd dt dt d dt d dt Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 13

14 Project Objective and Future Prosective Objective Obtain the comlete L/T searated cross section for the u- channel ω meson roduction To initiate more u-channel roduction studies Prosective (Fi-1 exeriment: E ) Extended u-channel ω roduction u-channel φ (s s ) roduction is ossible! Garth Huber has more to say on this during the Exclusive Meson Worksho Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 14

15 Backu Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 15

16 Fi- E Exeriment Fi- (E01-004) 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 u u d : ω (78): J P = 1, I G = 0, M ω =78 MeV. d Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 16

17 L/T Searation V irtu a l- h o to n o la riz a tio n : e e ' e ' ( E E ) Q 1 ta n Q 1 d d L d T d d dtd dt dt dt dt LT TT 1 cos cos Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 17

18 Rosenbluth Searation Exerimental differential cross section deend on the Longitudinal and Transverse art of the virtual hoton: ε: virtual hoton olarization Rosenbluth Searation method requires Searate measurements are taken at different ε (virtual hoton olarization) All hysics quantities such as Q, momentum and energy of virtual hoton 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. 18

19 Slide on combine HMS setting to get the azimuthal Slide on combine HMS settings to get the azimuthally coverage MC/exeriment ratio Exacted searated dsigma/dt Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 19

20 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. 0

21 Mandelstam variables (s,t,u-channels) Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 1

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

23 Vector meson (J P = 1 ) Wenliang Li, Det. of Physics, Univ. of Regina, Regina, SK S4S0A, Canada. 3

24 u-channel ω 0 Production (May Present) e N e (e, e π)n X e π Discovered during E exeriment e Missing mass eak is consistent with the mass of the omega meson (783 MeV). (e, e )X Not studied by any other exeriment or theory 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) (Fixed ) ( 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, 004 J. M. Laget, Phys. Rev. D 70, Published 8 Setember 004 It would be great if JML can calculate something similar for Fi- kinematics. 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