1. Charged Kaon Production Yield Studies with Stretcher Sergei Striganov Fermilab Future of Kaon Physics at Fermilab August 21, Fermilab

2. Introduction Target: estimate ratio of low energy charged kaon yields at 120 and 24 GeV/c There is no solid theoretical basis to create model of low-energy kaon production in proton- nucleus collisions Verify model estimates of low energy charged kaon yield in proton-nucleus interaction at 24 - 120 GeV/c Simulate kaon yield from thick target

3. Experimental data on low energy charged kaon production at small angles in proton-nucleus (p ≥ 24 GeV/c) Incident momentum (GeV/c) Secondary mometum (GeV/c) PartilceTargetExperimentComment 244 – 18K +,K - Be,Al,Cu,PbEichten et al 241.06, 1.4K-K- C,Cu,WAmann et al 280.66,0.73K-K- Al,Cu,PtShow et al 675 - 40K +,K - Be,Al,CuBozhko et al Normalization! 701.5K +,K - Al,WBarkov et al 1584.6K +,K - PbNA49trigger 2000.1-1.79K +,K - S,AuNA35central 4504,8K +,K - Be,S,PbNA44trigger 4506.75-67.5K +,K - BeNA56/SPY We need data near kaon momenta of 500 MeV/c at 120 GeV/c ( 0.00417) 710 MeV/c at 24 GeV/c ( 0.03)

4. Charged kaon ratio at 24 GeV/c K + /K - ratio at small kaon momentum and angles depends on primary proton energy and target Ratio falls as s -.5 between 12 and 70 GeV/c (s is center-of- mass energy)

5. Charged kaon ratio at 24 GeV/c 24 GeV/c  ratio = 2.6 for Be, ratio = 3.2 for Pb

6. Models LAQGSM is Los Alamos version of the Quark-Gluon String Model LAQGSM is implemented into MARS code system. It is possible to simulate thick target production. All LAQGSM results in this presentation were obtained using MARS-LAQGSM, not with the original LAQGSM! MARS default generator is based on approximation of measured inclusive spectra in hadron-proton collisions and nuclear modification factor calculated using additive quark model Efremov, Kazarnovsky, Paryev (EKP) developed closed analytical expressions for inclusive cross section for K + and K - production in proton-proton and proton-nucleus collisions based on experimental data Bonesini, Marchionni, Pietropaolo, Tabarelli proposed parameterization of experimental data measured in pBe interactions at 400-450 GeV/c. It is supposed that nuclear modification factor does not depend on secondary particle type and incident beam momentum. Radial scaling variable is used, so model could be applied at momentum > 20 GeV/c

7. Parametrizations and experimental data

8. Parametrizations and experimental data- II

9. MARS default generator and experimental data We need data near kaon momenta of 500 MeV/c at 120 GeV/c ( 0.00417) 710 MeV/c at 24 GeV/c ( 0.03)

10. MARS default generator and experimental data-II We need data near kaon momenta of 500 MeV/c at 120 GeV/c ( 0.00417) 710 MeV/c at 24 GeV/c ( 0.03)

11. MARS-LAQGSM generator and experimental data We need data near kaon momenta of 500 MeV/c at 120 GeV/c ( 0.00417) 710 MeV/c at 24 GeV/c ( 0.03)

12. MARS-LAQGSM generator and experimental data-II We need data near kaon momenta of 500 MeV/c at 120 GeV/c ( 0.00417) 710 MeV/c at 24 GeV/c ( 0.03)

13. From thin to thick target Kaon production target is about 0.6 -1 nuclear interaction length Low energy kaons could be produced in secondary, tertiary … interactions K + with kinetic energies 336-560 MeV are mostly produced in primary proton interactions and near elastic scattering of low energy positive kaon Results obtained using MARS- default and MARS-LAQGSM are similar About 30% of low energy positive kaons are produced by secondary neutrons and pions even in short (0.6 nuclear interaction length) target

14. 24 and 120 GeV/c charged meson yield. LAQGSM predictions

15. 120 to 24 GeV/c thick target ratio. LAQGSM predictions MARS-LAQGSM predicts rise of K + yield about 3.5 times from 24 to 120 GeV/c. It is not far from about 2.5 rise in experimental data from 24 to 158 GeV/c proton-lead interactions. MARS-LAQGSM predicts rise of K - yield about 5 times from 24 to 120 GeV/c. It is close to about 5 rise in experimental data from 24 to 158 GeV/c proton-lead interactions. K + /π + ratio increases about 15% from 24 to 120 GeV/c. K - /π - ratio rises about 70% in this energy range K + (120 GeV/c) / K + (24 GeV/c) 490 +- 4% MeV/c / 710 +- 5% MeV/c 1.2 540 +- 4% MeV/c / 710 +- 5% MeV/c 1.8

16. Conclusion Most of experimental data on low energy kaon yield at high proton momentum (> 158 GeV/c) were obtained with different biases. May be it is reason for disagreement between results of NA44 and SPY collaboration. Additional experimental data are needed to clarify situation (MIPP ?). Parametric models can not reproduced measurements at heavy nuclei MARS default generator agrees with data at 24 GeV/c, but underestimates charged kaon yield at larger energies MARS-LAQGSM generator underestimates kaon yield from Be target, but it predictions are closer to data for lead target. Large fraction of low momentum kaons are produced in secondary interactions even in short target platinum target MARS-LAQGSM thick target simulation predicts about 3.5 rise of low energy positive kaon yield from 24 to 120 GeV/c

17. BACKUP SLIDES

18. Normaliztaion of Bozhko et al data

19. Charged kaon production at 24 GeV/c

20. E802 data and models y=0.7 and m T -m p =0.26 GeV ↔ p=0.81 GeV/c and θ=45 0

21. Models and data at 12.9 GeV/c

22. Models and data Kapinos model (and original BKP model) can not reproduce data at large x (p/p 0 > 0.1) & small angle, and small x &large angles simultaneously (p is kaon and and p 0 is proton momentum) With Kapinos scale BKP model describes well data at p~1 GeV/c and p 0 > 12 GeV/c, with original scale BKP reproduces well high-x and low-angle experimental data LAQGSM systematically underestimates low-x measurements Both models reproduce well large angle e802 results at 14.6 GeV/c

23. From thin to thick target Simple linear dependence on target thickness is used in Kapinos model MARS-LAQGSM simulates kaon production in hadronic shower Simplest model – kaon production and absorption: θ~0 Σ in (exp(-Σ in x) - exp(-Σ out x))/(Σ out - Σ in ) ~ Σ in x exp(-(Σ in + Σ out )x/2) θ~1 1-exp(-Σ in x) Kaon production in secondary interactions is not important at least in 8-12 GeV/c momentum range