Neutrino-induced meson production model

for neutrino oscillation experiments

Satoshi NakamuraNuclear Theory Group

Contents

★ Introduction nN scattering for neutrino exp.

★ Dynamical coupled-channels (DCC) model for

, gN pN

, , , , pN ppN hN KL KS

★ Application of DCC model to

nN , , , , pN ppN hN KL KS

Near detector

Far detector

Comparison oscillation , q Dm2

q13 ≠ 0 (Daya-Bay, RENO, T2K, MINOS, Double-

Chooz)

Next-generation exp. leptonic CP, mass hierarchy

-n nucleon (nucleus) scattering needs to be understood more precisely

Wide kinematical region with different characteristic

Combination of different expertise is necessary

Collaboration at J-PARC Branch of KEK Theory Center

http://j-parc-th.kek.jp/html/English/e-index.html

Neutrino flux # of events of -n nucleus interaction

-n nucleus cross section

LBL

Many nucleon resonances in 2nd and 3rd resonance region

Resonance region

D

2nd 3rd

Not only 1 p production but also …Multi-channel reaction

2p production is comparable to 1p

h, K productions (background of proton decay exp.)

(MeV)

(Data)

Dealing with multi-channel reaction

Unitary coupled-channel model needs to be developed

Unitarity is missing in previous models Important 2 p production model is missing Previous models for K and h production are not well tested by data

Problems

★ Dynamical coupled-channels model for , gN pN , , , pN ppN hN

, KL KS

★ Application to nN , , , , pN ppN hN KL KS

Dynamical Coupled-Channel model for

, gN pN , , , , pN ppN hN KL KS

Kamano, Nakamura, Lee, Sato

Coupled-channel unitarity is fully taken into acount

DCC analysis of meson production data

Fully combined analysis of , gN pN , , , pN hN KL KS

(W ≤ 2.1 GeV)

Fitting ~380 parameters (N* mass, N* MB couplings, cutoffs)

to ~ 20,000 data points

Kamano, Nakamura, Lee, Sato, 2012

Vector current (Q2=0) for 1 p

Production is well-tested by data

Kamano, Nakamura, Lee, Sato, 2012

Vector current (Q2=0) for h

Production is well-tested by data

Kamano, Nakamura, Lee, Sato, 2012

Vector current (Q2=0) for K

Production is well-tested by data

Short Summary

• DCC model for , gN pN , , , , pN ppN hN KL KS

developed

• Model has been extensively tested by data

reliable vector current to be applied to n-scattering

• Check out JPS monthly magazine next (X 2,3) months for a review

PCAC-based application of DCC model to

forward nN , , , , pN ppN hN KL KS

Kamano, Nakamura, Lee, Sato, PRD 86, 097503 (2012)

Objectives

Set a starting point for full dynamical model

… we study only Q2=0 here.

Relative importance of different channels ( , , pN ppN

KY..)

Comparison with Rein-Sehgal model (in most MC code)

• nN reaction, vector and axial currents contribute.

• For Q2=0 , only survives.

• PCAC relation, is used.

• nN reaction amplitude is related to pN reaction amplitude

PCAC-based calculation of nN reaction

Results

SLpN

ppN KShN

KL

Prediction based on model well tested by data

pN dominates for W ≤ 1.5 GeV

ppN becomes comparable to pN for W ≥ 1.5 GeV

Smaller contribution from hN and KY O(10-1) - O(10-2)

Comparison with Rein-Sehgal model

Lower D peak of RS model

RS overestimate in higher energy regions (DCC model is tested by data)

Comparison with Rein-Sehgal model

Summary

DCC model for forward nN , , , , pN ppN hN KL KS via

PCAC

Prediction based on model well tested by data

ppN comparable to pN for W ≥ 1.5 GeV (first nN ppN)

First data-based prediction for nN , hN KY

Comparison with Rein-Sehgal model :

Significant difference

Full development of dynamical axial current is underway

BACKUP

Formalism

Cross section for nN X ( X = , , , , pN ppN hN KL KS )

q 0

Q20

CVC & PCAC

LSZ & smoothness

Finally spNX is from our DCC model

Previous models for n-induced 1p production in resonance region

Rein et al. (1981), (1987) ; Lalalulich et al. (2005), (2006)

Hernandez et al. (2007), (2010) ; Lalakulich et al. (2010)

Sato, Lee (2003), (2005)

resonant only

+ non-resonant (tree-level)

+ rescattering ( p N unitarity)

Partial wave amplitudes of pi N scattering

Kamano, Nakamura, Lee, Sato, 2012

Previous model (fitted to pN pN data only)[PRC76 065201 (2007)]

Real part

Imaginary part

Eta production reactions

Kamano, Nakamura, Lee, Sato, 2012

KY production reactions

1732 MeV

1845 MeV

1985 MeV

2031 MeV

1757 MeV

1879 MeV

1966 MeV

2059 MeV

1792 MeV

1879 MeV

1966 MeV

2059 MeV

Kamano, Nakamura, Lee, Sato, 2012

J-PARC proposalπN ππN in high-mass N* region

(K. Hicks, K. Imai et al.)

There is NO practical data that can be used for testing models for πN ππN above W > 1.5 GeV.

For W > 1.5 GeV, πN ππN becomes the dominant process of the πN reactions. (same applied to n-scattering)

Model for nN ππN will be essetial piece in MC

πN ππN data are essential to develop nN ππN model

Please support the proposal !

F2 from RS model

F2 from RS model

Spectrum of N* resonances

Real parts of N* pole values

L2I 2J

PDG Ours

N* with 3*, 4* 1816

N* with 1*, 2* 5

PDG 4*

PDG 3*

Ours

Kamano, Nakamura, Lee, Sato ,2012

SL model applied to -n nucleus scattering

1 p production

Szczerbinska et al. (2007)

SL model applied to -n nucleus scattering

coherent p production

g + 12C p0 + 12C nm + 12C m- + p0 + 12C

Nakamura et al. (2010)

Dealing with multi-channel reaction

e.g., n-induced K production

Tree-level models

DS=0 : Adera et al., (2010)

DS=1 : Rafi Alam et al., (2010), (2012)

DCC model for , gN pN , , , pN hN KL KS

reactionsFor analyzing data to identify nucleon resonances (Baryon spectroscopy)* Well-established meson-exchange mechanism for meson-baryon interactions

* Description of nucleon resonance (N*)

, g p

N B

M

N*

* Unitarity , , , ( , , ), , gN pN hN ppN pD rN sN KL KS coupled-channels

Resonance region

D

2nd 3rd

Many nucleon resonances in 2nd and 3rd resonance region

(MeV)