HES HKS Analysis meeting JLab Toshi Gogami

Preliminary results of p(γ*,K + )Λ 2012/9/14JPS meeting in Kyoto, Toshi Gogami2 Preliminary JLab E (HES-HKS) 192±6±89 [ nb / sr ] SAPHIR : K.H.Glander et al., Eur. Phys. J. A 19, (2004) CLAS : R.Bradford et al., Phys. Rev. C 73, (2006) ( JLab E05-115, Q 2 ~ 0.01 [GeV/c] 2 )

Definition of cross section Solid angle of HKS Event by event The number of VP Including HES solid angle and acceptance The number of VP Including HES solid angle and acceptance New way to estimate

VP flux factor Γ ( E e, ω, θ e’ ) Ee = GeV ω = 1.5 GeV Jab E05-115, Polyethylene target θe ’ (lab)

VP flux factor vs. p and θ ~ ~ 0.01 HES HKS

Integrated VP flux factor

VP flux factor Divided into 7 regions Jab E05-115, Polyethylene target 67 θe ’ (lab)

VP flux factor Divided into 7 regions Jab E05-115, Polyethylene target Q 2 [GeV]

Γ  Γ’ ( Region 4 ) SIMULATION – GeV/c ( < W < GeV) Γ’ ~ × [ /N e ] Γ ~ [ / GeV / sr / N e ] Number of VP ~ ×10 12 ± ×10 10

Results θe' (Lab)θgK (CM)Q 2 [GeV] 2 ΓΓ'Number of VPsolid angles (HES,HKS)[msr] NΛNΛ Cross section [ nb/sr ] ± e-3±5.9e e e+12± e , ( ) ( ) ( ) ± e-3±2.6e e e+12 ± e , ( ) ( ) ( ) ± e-3±3.2e e e+12 ± e , ( ) ( ) ( ) ± e-3±8.3e e e+12 ± e , ( ) ( ) ( ) ± ±9.4e e e+12 ± e , ( ) ( ) ( ) ± e- 2±1.629e e e+12 ± e , ( ) ( ) ( ) ± e- 2±1.600e e e+12± e , ( ) ( ) ( )

Angular dependence SAPHIR : K.H.Glander et al., Eur. Phys. J. A 19, (2004) CLAS : R.Bradford et al., Phys. Rev. C 73, (2006)

Q 2 dependence

SAPHIR : K.H.Glander et al., Eur. Phys. J. A 19, (2004)

Coincidence cut for 52 Cr TCut cut_1 = "abs(ctime+54.6)<1.0 && <runnum && runnum< "; TCut cut_2 = “abs(ctime+54.8)<1.0 && <runnum && runnum< "; TCut cut_3 = "abs(htimetar-etimetar+54.9)<1.0 && ( <runnum && runnum< )"; TCut cut_41 = "abs(htimetar-etimetar+54.9)<1.0 && ( <runnum && runnum< )"; TCut cut_42 = "abs(htimetar-etimetar+54.3) )";

END

Comparison with data of JLab Hall-A Large longitudinal term contributions? p(γ*,K + )Λ ~ JLab E (HES-HKS) W ~ 1.9 GeV Q 2 ~ 0.01 [GeV/c] 2 p(γ*,K + )Λ ~ JLab E (HES-HKS) W ~ 1.9 GeV Q 2 ~ 0.01 [GeV/c] 2 Preliminary p(γ*,K + )Λ ~ JLab E W ~ 2.2 GeV Q 2 ~ 0.07 [GeV/c] 2 p(γ*,K + )Λ ~ JLab E W ~ 2.2 GeV Q 2 ~ 0.07 [GeV/c] 2 SAPHIR : K.H.Glander et al., Eur. Phys. J. A 19, (2004) CLAS : R.Bradford et al., Phys. Rev. C 73, (2006) JLab E : P.Markoviz et al., Proceedings of SENDAI08 (2009) 2012/9/14JPS meeting in Kyoto, Toshi Gogami17

Considered efficiencies Simulation 2012/9/14JPS meeting in Kyoto, Toshi Gogami18

K + production at small angles electroproduction SL: 0.41 =  (  = 0.7 ) a steep Q 2 dependence ? P. Bydzovsky’s presentation at ECT* 2011 (  *,K + ) JLab Hall-A E W=1.9 GeV Q 2 =0.01 (GeV/c) /9/14JPS meeting in Kyoto, Toshi Gogami 19