Weak Coherent Kaon Production

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Weak Coherent Kaon Production
L. Alvarez-Ruso1, J. Nieves1, I. Ruiz Simo2, M.
Valverde3, M. Vicente Vacas1

1. IFIC, Universidad de Valencia
2. Universidad de Granada
3. RCNP, Osaka

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Weak Coherent Kaon Production
L. Alvarez-Ruso1, J. Nieves1, I. Ruiz Simo2, M.
Valverde3, M. Vicente Vacas1

1. IFIC, Universidad de Valencia
2. Universidad de Granada
3. RCNP, Osaka

6
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

7
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

8
The model

1. Microscopic kaon production on the nucleon
2. The coherent reaction
3. Kaon distortion

9
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 S1 baryon resonances ) Extended
  validity of model

CT
KP
¼F, F
Cr, Cr
10
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)

11
The model

• Microscopic kaon production on the nucleon Rafi
  Alam et al., PRD82
• vs S 0 from GENIE

12
The model

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

13
The model

• 3. Kaon distortion (with DWBA)
• or in the eikonal approximation
• The optical potential
• C0.13 or 0.114

à Klein-Gordon eq.
Cabrera, Vicente Vacas, PRC69
14
Results

• In the Impulse Approximation
• Very small cross section

15
Results

• In the Impulse Approximation
• Very small cross section
• Compare to Coh¼ (on 12C)
• ¾(Coh¼,1 GeV) 0.05-0.1 gtgt ¾ (CohK,1.35
  GeV) 0.00014

16
Results

• In the Impulse Approximation
• Very small cross section why?

17
Results

• In the Impulse Approximation
• Very small cross section why? because K is heavy

18
Results

• In the Impulse Approximation
• Very small cross section why? because K is heavy

19
Results

• In the Impulse Approximation
• Very small cross section why? because K is heavy
  )
• Sensitive to the nuclear density distribution

20
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)
21
Results

• In the Impulse Approximation. Contribution from
  different mechanisms

• CT is the largest contribution, followed by Cr
• Interference stronger than in the free case

22
Results

• With Kaon distortion. Kaon momentum
  distributions

23
Results

• With Kaon distortion. Kaon momentum
  distributions
• Eikonal approximation breaks down at low pK

24
Results

• With Kaon distortion. Kaon momentum
  distributions
• Eikonal approximation breaks down at low pK,
  unlike in Coh¼

LAR et al., PRC
25
Results

• With Kaon distortion. Angular distributions

26
Results

• With Kaon distortion. Angular distributions

27
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

28
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

29
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

30
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)
31
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

à Klein-Gordon eq.
Ramos, Oset, NPA 671 (2000)
32
The model

• 3. antiKaon distortion (with DWBA)
• The optical potential
• Very different interaction vs Kaon case

à Klein-Gordon eq.
Ramos, Oset, NPA 671 (2000)
33
Results

• With antiKaon distortion. Momentum distributions
  

34
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 large kaon mass
• Destructive interference
• Kaon distortion (stronger for K- as expected)
• Eikonal approximation is wrong at low momenta