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Weak Coherent Kaon Production: Alvarez-Ruso, Nieves, Ruiz-Simo, Valverde, Vicente Vacas

This study examines the production of kaons in weak coherent interactions, specifically the production of kaons in (anti)neutrino-nucleus interactions. It explores the microscopic model for kaon production on the nucleon and analyzes the effects of kaon distortion on the momentum and angular distributions. The study also investigates the production of coherent kaons with antineutrinos, considering both elementary interactions and contributions from strange baryons and resonances.

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Weak Coherent Kaon Production: Alvarez-Ruso, Nieves, Ruiz-Simo, Valverde, Vicente Vacas

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  1. Weak Coherent Kaon Production L. Alvarez-Ruso1, J. Nieves1, I. Ruiz Simo2, M. Valverde3, M. Vicente Vacas1 • IFIC, Universidad de Valencia • Universidad de Granada • RCNP, Osaka TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AAAAAA

  2. Weak Coherent Kaon Production L. Alvarez-Ruso1, J. Nieves1, I. Ruiz Simo2, M. Valverde3, M. Vicente Vacas1 • IFIC, Universidad de Valencia • Universidad de Granada • RCNP, Osaka

  3. Introduction • QE and 1¼ are the most important (large and relevant for oscillations) (anti)º interaction channels in the few-GeV region, but there are others… • Strangeness production: • ¢S = 0 e.g. • ¢S = 1 : • Cabibbo suppressed but with lower thresholds than ¢S = 0 • Hyperon e.g. • Kaon: • Background for proton decay p !º K+ • Accessible by Minerºa but also MiniBooNE, T2K, … • There is a coherent channel

  4. Introduction • QE and 1¼ are the most important (large and relevant for oscillations) (anti)º interaction channels in the few-GeV region, but there are others… • Strangeness production: • ¢S = 0 e.g. • ¢S = -1 : • Cabibbo suppressed but with lower thresholds than ¢S = 0 • antiKaon: • Accessible by Minerºa but also MiniBooNE, T2K, … • Potentially interesting for antiº beams • There is a coherent channel

  5. The model • Microscopic kaon production on the nucleon • The coherent reaction • Kaon distortion

  6. The model • Microscopic kaon production on the nucleon Rafi Alam et al., PRD82 • Includes all terms in SU(3)chiral Lagrangians at leading order • Parameters: f¼ , ¹p and ¹n, D and F (from semileptonic decays) • A global dipole form factor : F(q2)=(1-q2/M2F)-2 , MF = 1 GeV • Absence of S=1 baryon resonances )Extended validity of model CT KP ¼F, ´F Cr§, Cr¤

  7. The model • Microscopic kaon production on the nucleon Rafi Alam et al., PRD82 • Includes all terms in SU(3)chiral Lagrangians at leading order • A global dipole form factor : F(q2)=(1-q2/M2F)-2 , MF = 1 GeV (§ 10%)

  8. The model • Microscopic kaon production on the nucleon Rafi Alam et al., PRD82 • vs ¢S = 0 from GENIE

  9. The model 2. The coherent reaction • Amplitude: • Nuclear current: • ¼F, ´Fvanish with the sum • initial and final nucleons taken on-shell with averaged momenta:

  10. The model 3. Kaon distortion (with DWBA) or in the eikonal approximation: The optical potential: C=0.13 or 0.114 ÃKlein-Gordon eq. Cabrera, Vicente Vacas, PRC69

  11. Results • In the Impulse Approximation: • Very smallcross section…

  12. Results • In the Impulse Approximation: • Very smallcross section… • Compare to Coh¼+ (on 12C): ¾(Coh¼+,1 GeV)~ 0.05-0.1 >> ¾(CohK+,1.35 GeV)~ 0.00014

  13. Results • In the Impulse Approximation: • Very smallcross section… why?

  14. Results • In the Impulse Approximation: • Very smallcross section… why? because K is heavy

  15. Results • In the Impulse Approximation: • Very smallcross section… why? because K is heavy

  16. Results • In the Impulse Approximation: • Very smallcross section… why? because K is heavy ) • Sensitive to the nuclear density distribution

  17. Results • In the Impulse Approximation. Contribution from different mechanisms: • CT is the largest contribution, followed by Cr¤ • Interference stronger than in the free case Rafi Alam et al., PRD82 (2010)

  18. Results • In the Impulse Approximation. Contribution from different mechanisms: • CT is the largest contribution, followed by Cr¤ • Interference stronger than in the free case

  19. Results • With Kaon distortion. Kaon momentum distributions:

  20. Results • With Kaon distortion. Kaon momentum distributions: • Eikonal approximation breaks down at low |pK|

  21. Results • With Kaon distortion. Kaon momentum distributions: • Eikonal approximation breaks down at low |pK|, unlike in Coh¼ LAR et al., PRC

  22. Results • With Kaon distortion. Angular distributions:

  23. Results • With Kaon distortion. Angular distributions:

  24. The model • Coherent K- production with antineutrinos • Elementary interaction: Rafi Alam et al., PRD 85 • Direct terms with strange baryons (¤, §, §*(1385)) in the intermediate state

  25. The model • Coherent K- production with antineutrinos • Elementary interaction: Rafi Alam et al., PRD 85 • N-§*(1385) transition: C3V, C4V, C5V, C3A, C4A, C5A, C6A ff related to those of N-¢(1232) using SU(3) symmetry • In particular: C5A(0) Ã off-diagonal G-T

  26. The model • Coherent K- production with antineutrinos • Elementary interaction: Rafi Alam et al., PRD 85 • Small contribution from §*(1385): it is below K production threshold

  27. Results • Coherent K- production with antineutrinos • In the Impulse Approximation. Contribution from different mechanisms: • Largest contribution from CT • Strong destructive interference • (Relatively) large§* Rafi Alam et al., PRD85 (2012)

  28. The model 3. antiKaon distortion (with DWBA) The optical potential: • K-p interaction dominated by ¤(1405) resonance • ¤(1405) dynamically generated by s-wave meson-baryon rescattering in coupled channels • Dressing of meson propagators (1p1h, ¢h) • Self consistent treatment of antiK ÃKlein-Gordon eq. Ramos, Oset, NPA 671 (2000)

  29. The model 3. antiKaon distortion (with DWBA) The optical potential: • Very different interaction vs Kaon case: ÃKlein-Gordon eq. Ramos, Oset, NPA 671 (2000)

  30. Results • With antiKaon distortion. Momentum distributions:

  31. Conclusions • (anti)Neutrino induced coherent (anti)kaon production has been studied • Microscopic production mechanism based on SU(3)chiral Lagrangians • Coherent sum over all (noninteracting) nucleons • DWIA for the outgoing (anti)kaon by solving the KG eq. with a realistic density-dependent potential • Small cross sections are obtained due to: • Small (Cabibbo suppressed) c. s. on nucleons • Large momentum transferred to the nucleus because of the largekaon mass • Destructive interference • Kaondistortion (stronger for K- as expected) • Eikonal approximation is wrong at low momenta

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