Charged Kaon Production Yield Studies with Stretcher

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) 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 = 2.2 for Pb

6. 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 Models

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 mT-mp=0.26 GeV ↔ p=0.81 GeV/c and θ=450

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/p0> 0.1) & small angle, and small x &large angles simultaneously (p is kaon and and p0 is proton momentum) • With Kapinos scale BKP model describes well data at p~1 GeV/c and p0 > 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 Σin (exp(-Σin x) - exp(-Σout x))/(Σout - Σin) ~ Σinx exp(-(Σin+ Σout )x/2) θ~1 1-exp(-Σin x) • Kaon production in secondary interactions is not important at least in 8-12 GeV/c momentum range