Hyperon Produc-on Simula-on Updates (K + Σ 0, K + Λ 0, K 0 Σ + rates) Ye Tian June 27, 2017

Transcription

1 Hyperon Produc-on Simula-on Updates (K + Σ, K + Λ, K Σ + rates) Ye Tian June 27, 217 1

2 Major Concern Ø Background effects: The weak decays of the hyperons preferen-ally emit pions along the direc-on of the hyperon spin, inducing a helicity dependent background. The LGC is the device poten-ally most sensi-ve to this false asymmetry. (LGC threshold ~5MeV) Ø The background asymmetry: The measured asymmetries are at 5x1-3 level. We would like asymmetry in the LGC singles rate to be at the 1-4 level (arises from the dead -me caused by the accidental singles rate in the LGC). 2

3 Hyperon Event Generator v Electroproduction (available from HallB hyperon group and the generator are checked with data. ) with Ebeam=11GeV, 3.4 GeV<Q 2 <12 GeV, and threshold (GeV) <W< GeV. ( v Bremsstrahlung photoproduction event generator that is based on the Ugent model: Phys. Rev. C73,4527(26) and Phys. Rev. C75,4524(27) ( cross section tables ) with Ebeam=11GeV and 1.61(9)GeV<W<4.65 GeV. Two versions are available: RPR-27 version for channels: γp->k + Λ, K + Σ and K Σ + RPR-211 version only for channels: γp->k + Λ

4 Electroproduc-on Extrapola-on of the cross sec-on into larger W region (from W-dependence of the photoproduc-on data) V. Klimenko, E. Golovach, and V. Mokeev (Mocow State University and JLab 4

5 RPR-27 Version model and data comparison h^ps://arxiv.org/abs/ v3 It turns out that RPR-27 version is constrained to forward angle (cosθ * k >.35).

6 RPR-211 Version model and data comparison h^ps://arxiv.org/abs/ v3 It turns out that RPR-211 version is consistent with data, but it is only available for γp->k + Λ channel now.

7 Part I K + Λ Electro-and photon-produc-on simula-on comparison 7

8 K + Λ simula-on u The electroproduc-on simula-on condi-on: e - beam E beam =11 GeV, 3.4GeV 2 <Q<12GeV 2, and 1.61 GeV<W<2.835 GeV u The photonproduc-on simula-on condi-on: The number of bremsstrahlung photons with energy between ω max andω min!! = 4!!"!!"!!!"#!!"# 3!!!!"#! + 3!!!!"#!!"# 8!!!! =!! =!! 1! +!!!!!!!!!!!!!!!! =!!!! +!!!!!!!!! d = ρ t where ρ is target density and t is target thickness 8

9 N(ω) !! =!!!! +!!!!!!!!! ω (GeV) γp K + Y Λ or Σ beam.energy() 7 6 htemp Entries 5 Mean RMS Event generator ω photon energy beam.energy()

10 Event Generator Scheme Model table: W, cosθ k, σ, dσ/dω Generate Random Photon Energy follow the func-on N(ω) Phase space calcula-on Fermi Momentum for the target Nucleon (deuteron target) DCS calcula-on extrapola-on No DCS<RN Yes RN is uniformly distributed floa-ng points between and maximum of unpolarized DCS Fill the tree and txt file GEMC Anlyse

11 5 4 ϒP K + Λ Simulation Results P_lamda_hist Entries 375 Mean RMS Px_lamda_hist Entries 375 Mean.2349 RMS Λ p (MeV) Λ Px Λ (MeV) 1 Py_lamda_hist Entries 375 Mean.6924 RMS Pz_lamda_hist Entries 375 Mean RMS Py (MeV) Λ Pz Λ (MeV) 11

12 ϒP K + Λ Simulation Results theta_hist Entries 375 Mean 3.91 RMS phi_hist Entries 375 Mean RMS Λ θ Λ φ Λ 12

13 25 2 ϒP K + Λ Simulation Results P_karon_hist Entries 375 Mean 1626 RMS Px_karon_hist Entries 375 Mean.2349 RMS K P K (MeV) Px K (MeV) 1 8 Py_karon_hist Entries 375 Mean.6924 RMS Pz_karon_hist Entries 375 Mean 1547 RMS Py (MeV) K Pz K (MeV) 13

14 ϒP K + Λ Simulation Results theta_karon_hist Entries 375 Mean RMS phi_karon_hist Entries 375 Mean 18 RMS K θ K φ K 14

15 Reconstruct π Analysis 1 2 ϒ p K + Λ 4 3 n π 2x1 6!!! = Λ!!!! in the same event Reconstruct π mtid, mpid, tid, and pid 5 6 u Gem: flux hit detector ID = 1, sub-detector ID=1, 2, 3, 4, 5, subsubdetector=1 u Lgc: flux hit detector ID = 2, sub-detector ID=1, 2. subsubdetector=1 u Ecal: flux hit detector ID = 3, sub-detector ID =1, and subsubdetector=1 ϒ ϒ e - e +

16 ϒP->K + Λ 9 8 gem Er_gem_hist Entries 921 Mean 2.97 RMS lgc Er_lgc_hist Entries 9212 Mean 2.98 RMS K Λ photoproduction 7 + K Λ photoproduction K Λ electroproduction K Λ electroproduction Cross sec-on weighted PVDIS acceptance E ec beam γ + K Λ photoproduction (GeV) Er_ec_hist Entries 592 Mean 2.28 RMS K Λ electroproduction E RPR-211 version: photoproduc-on E γ : bremsstrahlung photon energy Er = (W 2 -m p2 )/2m p Hall B Hyperon event generator (EG): electroproduc-on virtual photon energy Eγ*= E e -E e beam γ (GeV) E beam γ (GeV) 16

17 12 π Momentum Distribu-on in the Lab Frame gem momen_pi_gem_2r_hist Entries 222 Mean RMS lgc momen_pi_lgc_2r_hist Entries 223 Mean RMS K Λ photoproduction + K Λ electroproduction K Λ photoproduction + K Λ electroproduction p π p π 6 ec momen_pi_ec_2r_hist Entries 114 Mean RMS RPR-211 version: photoproduc-on K Λ photoproduction + K Λ electroproduction Hall B Hyperon event generator (EG): electroproduc-on p π 17

18 Bremsstrahlung photoproduc-on K + Λ Rate Comparison (MHz) Rate Trigger rate Gem (3) =.22 PMT>=2; Nphe>=2 Lgc = x1-3 Ecal =.12 Electroproduc-on γ e - e + (MHz) Rate Trigger rate Gem (3) 8.2x1-4 Lgc 8.8x x1-5 Ecal 4.45x1-4 Rate = L!"!!!!!"#!!"#$, L =!"!"!!!"!.!"#!.!"!"!"!!"!#$!.!!"!!"!.!"#!"!! 18

19 comparison (MHz) Rate Trigger rate Gem (3) =.22 Lgc = x1-3 Ecal =.12 19

20 Part II 2

21 Other Hyperon Produc-on Channel Study 1 2 ϒP->K + Σ 3 4 γλ 6 5 nπ m-d -d 1 2 ϒP->K Σ pπ 2γ RPR-27 version: ϒP->K + Σ and ϒP->K Σ + RPR-211 version: ϒP->K + Λ γ e - e + e - e + 21

22 ϒP->K + Σ comparison (MHz) Rate Trigger rate Gem (3).292 lgc x1-3 ec.141 ϒP->K Σ + (MHz) Rate Trigger rate Gem (3).77 lgc x1-3 ec.26 22

23 (MHz) Summary ϒP->K + Σ ϒP->K + Λ ϒP->K Σ + lgc Trigger rate 6.11x x x1-3 Based on your note: Hyperon Produc-on and Asymmetries 23

24 The asymmetry in the background is determined by decay asymmetry parameters a and by the cosθ of the decay π Need the cosθ π informa-on to study the cancella-on effect. Any comments and sugges-ons? 24

25 Backup 25

26 γ 1 Momentum for Λ produc-on gem r1_gem_hist Entries Mean RMS gem r1_gem_x_hist Entries Mean RMS !! !!! γ [MeV] 1 gem r1_gem_y_hist Entries Mean RMS γ [MeV] 1 gem r1_gem_z_hist Entries Mean RMS !!! 8 6 4!!! γ [MeV] γ [MeV] 1 26

27 The Generated Σ Momentum Distribu-ons Pz_lamda_hist Entries 2 Mean RMS Px_lamda_hist Entries 2 Mean.1525 RMS Pz Σ Px Σ Py_lamda_hist Entries 2 Mean.1117 RMS P_lamda_hist Entries 2 Mean 118 RMS Py Σ P Σ 27

28 The Generated Σ + Momentum Distribu-ons Pz_lamda_hist Entries 2 Mean 1155 RMS Px_lamda_hist Entries 2 Mean.1336 RMS Due to the model extrapola-on Pz Σ Px Σ Py_lamda_hist Entries 2 Mean.2823 RMS P_lamda_hist Entries 2 Mean 1242 RMS Py + Σ P Σ +

29 2ϒ event rate per sector K + Λ π n 2ϒ Rate (MHz) m-d=5 and 6 Trigger rate (MHz) PMT>=2; Nphe>=2 Gem (3).1896 lgc x1-4 ec.184 Rate = L!"!!!!!"#!!"#$, L =!"!"!!!"!.!"#!.!"!"!"!!"!#$!.!!"!!"!.!"#!"!! 29

30 e - event rate per sector K + Λ π n 2ϒ e - e + Rate (MHz) m-d=5/6 Trigger rate (MHz) Gem (3).27 lgc x1-3 ec.567 3

31 e + event rate per sector K + Λ π n 2ϒ e - e + Rate (MHz) m-d=5/6 Gem (3).173 Trigger rate (MHz) lgc x1-3 ec.3313 (trigger for p>1gev) 31

32 18 16 gem Er_gem_hist Entries Mean RMS.5776 Er_lgc_hist Entries 1642 Mean RMS Bremsstrahlung Photon Energy lgc + K Σ 14 + K Σ K Σ K Σ 8 + K Λ 8 + K Λ beam E (GeV) γ beam E (GeV) γ 6 5 ec + K Σ Er_ec_hist Entries 5651 Mean 2.2 RMS.5738 PVDIS acceptance Cross sec-on weighted 4 + K Σ 3 + K Λ beam E (GeV) γ 32