L(1405)/S(1385) Photoproduction in SLH2 Deuk Soon Ahn

t-channel dynamics dominance Basic assumption: At E γ ≈ 2 GeV, the γ p → K + π 0 Λ and γ p→K + π Σ reactions in the region of the Σ(1385) and the Λ(1405) resonances are largely driven by the K - t-channel exchange. 1.t- channel dynamics, to gain understanding of the K-p-> π 0 Λ and of the K-p-> πΣ amplitudes below the KN thereshold, where they are dominated by the Σ(1385) and Λ(1405) resonances. 2. Ingoing photon dissociates into real K+ and virtual K-, the off-shell K-scattering subsequently off the proton target to the dsigma/dt with increasing |t|. (t means the square of the 4 momentum transfer from the proton to the L(1405)and S(1385)) 3. Theoretical differential cross sections for the γ p → K + (π 0 Λ) and γ p → K + (πΣ) reactions in the region of the Σ(1385) and the Λ(1405) resonances.(double kaon pole term contribution is large.) Nucl. Phys. A 748 (2005) 499

Old data: Production of hyperons by virtual photons T. Azemoon et al. NP B95 (1975) 77 e - p →e - K + Y Y = Λ, Σ, Σ(1385), Λ(1405), Λ(1520) Rapid fall-off suggesting a t-channel exchange process

w = (π Y) total center of mass energy The γ p → K + π 0 Λ and γ p → K + π Σ cross sections as functions of the total π Y center of mass energy for different values of E γ

W=1.415 W=1.425 W=1.405 W=1.395 W=1.435 Double pole term single pole term

Event Selction CutHORIVERTHORI+VERTComments Analyzed Event ntag= Itagc.f> ~4.6% increased ntrk> K+ PID (3sigma) DecayInFlight e+e- bar <vtz< Vtz w/Cu cut ~2.5% decreased npl(1)=0.or.npl(2)= <Eg<1.93,2.27<Eg<

MissingMass –Z-vertex CutZ-vertex, X-Vertex X-vertx, Y-vertex in the target region for double track events. Coming from target cell. Because of extended size of photon beam (especially in Hori) part of photon beam hit the target cell(Cu) and events produced from there <vtz< <vtz< <vtz< <vtz< <vtz< <vtz<-1000

Photon energy spectrum for ntag=1or2 events by kato’s itagc.f Rejected events by tagcut using npl Shieding materials are placed in High electron E of tagger(corresponding Low photon energy). There remains possibility that recoil electron with high energy outside the range of tagger. Or produce the shower at the material. npl1=0or npl2=0 is the number of hits which is not associated in PL. (selected event for which is no other hit than recoil electron, at least one of two. Because of a few dead stripes in SSD layer. We allow there is no hit in these strips to save tracks passed these area.

MissingMass & momemtum transfer MissingMass|t|-|t|min Counts

0<|t|-|t|min< <|t|-|t|min< <|t|-|t|min< <|t|-|t|min< <|t|-|t|min< <|t|-|t|min<0.60

MissingMass(GeV/c^2) Counts/5MeV MissingMass –E18bins (E )

Photon Energy |t|-|t|min K+MissingMass L(1116) S(1193) S(1385)/ L(1116) L(1520)nonresont

Eg(GeV) MMp(g,K+) – all T &T1-T5 cut All |t|-|t|min 0.<|t|-|t|min< <|t|-|t|min< <|t|-|t|min< <|t|-|t|min< <|t|-|t|min<0.50

Differential cross section Minimum momemtum transfer |t|min varies drastically when photon energy changed. -> t’ = |t|-|t|min is introduced. ds/dt’ =a (exp(-bt)) b : slope ； The yield which is corrected acceptance is fitted with exponential function Photon normalization not included yet. dt A * (N K + - B) dd N B * N T * dt =

Yields of L(1116) as function of|t|-|t|min, Data |t|-|t|min Counts

Acceptance of L(1116) as function of |t|-|t|min, MC |t|-|t|min

dsigma/dt (Abr.Unit.) |t|-|t|min Differential Cross Section :Acceptance corrected yield|t|-|t|min distribution on L(1116)

Energy dependence of slope parameter b

Yields of L(1405)/S(1385) |t|-|t|min, Data |t|-|t|min Counts

Acceptance of L(1405) |t|-|t|min, MC |t|-|t|min

dsigma/dt (Abr.Unit.) |t|-|t|min Differential Cross Section of L(1405)/S(1385)

Energy dependence of slope parameter b

Yields of L(1520) |t|-|t|min, Data |t|-|t|min Counts

Acceptance of L(1520) |t|-|t|min, MC |t|-|t|min

dsigma/dt (Abr.Unit.) |t|-|t|min Differential Cross Section of L(1520)

Energy dependence of slope parameter b

Acceptance-corrected t’ ; 1.35<MM<1.44(9 MMslice)&E1-E9 1.35<MM< <MM< <MM< <MM< <MM< <MM<1.41

1.41<MM< <MM< <MM<1.44

Energy dependence of slope parameter b 1.35<MM< <MM< <MM< <MM< <MM< <MM<1.41

1.41<MM< <MM< <MM< <MM< <MM< <MM< <MM< <MM< <Eg< <Eg< <Eg< b parameter