neutrino-induced meson productions satoshi nakamura osaka university, japan collaborators : h....

Neutrino-induced meson productions

Satoshi Nakamura

Osaka University, Japan

Collaborators : H. Kamano (RCNP, Osaka Univ.), T. Sato (Osaka Univ.) T.-S.H. Lee (Argonne Nat’l Lab)

Contents

★ Introduction nN scattering in resonance region

★ Dynamical coupled-channels (DCC) model

Analysis of g , N pN , , , pN hN KL KS data

Extension to nN l-X ( X= , , , , pN ppN hN KL

KS )

★ Results for nN l-X

Introduction

Neutrino-nucleus scattering for n-oscillation experiments

n

Neutrino-nucleus interactions neutrino detectors (16O, 12C, 36Ar, … )

Neutrino-nucleus interactions need to be known for neutrino flux measurement

DISregion

QEregion

RESregion

Next-generation exp. leptonic CP, mass hierarchy

-n 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

T2K

Neutrino-nucleus scattering for n-oscillation experiments

Atmospheric n



Resonance region (single nucleon)

D

2nd 3rd

Multi-channel reaction

2p production is comparable to 1p

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

(MeV)

(Data)

gN X

GOAL : Develop nN-interaction model in resonance region

We develop a Unitary coupled-channels model

(multi-channel) Unitarity is missing Important 2 p production model is missing

Problems in previous models

★ Dynamical coupled-channels (DCC) model for , gN pN , , , , pN ppN hN KL

KS

★ Extension to nN l-X ( X= , , , , pN ppN hN KL KS )

Our strategy to overcome the problems…

Dynamical Coupled-Channels model

for meson productions

,

Coupled-channel unitarity is fully taken into account

Kamano et al., PRC 88, 035209 (2013)

In addition, , gN W±N, ZN channels are included perturbatively

DCC analysis of meson production data

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

and polarization observables (W ≤ 2.1 GeV)

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

to fit ~ 20,000 data points

Kamano, Nakamura, Lee, Sato, PRC 88 (2013)

Partial wave amplitudes of p N scattering

Kamano, Nakamura, Lee, Sato,

PRC 88 (2013)

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

Real part

Imaginary partData: SAID pN amplitude

Constraint on axial current through PCAC

Kamano, Nakamura, Lee, Sato, 2012

Vector current (Q2=0) for 1 p

Production is well-tested by data

Kamano, Nakamura, Lee, Sato, PRC 88 (2013)

Model for vector & axial currents is necessary

Extension to full kinematical region Q2≠0

DCC model for neutrino interaction

n

Forward limit Q2=0

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

spNX snNX via PCAC

Vector current

Q2=0

gp MB

gn pN isospin separation

necessary for calculating n-interaction

Q2≠0 (electromagnetic form factors for VNN* couplings)

obtainable from (e,e’ p), (e,e’ X) data analysis

We’ve done first analysis of all these reactions VNN*(Q2) fixed neutrino reactions


Q2=0

non-resonant mechanisms

resonant mechanisms

Interference among resonances and background can be made under control within DCC model

Axial current


Caveat : phenomenological axial currents are added to maintain PCAC relation

to be improved in future

Axial current

Q2≠0

non-resonant mechanisms

resonant mechanisms


MA=1.02 GeV

: axial form factors

More neutrino data are necessary to fix axial form factors for ANN*

Sato et al. PRC 67 (2003)

Neutrino cross sections will be predicted with this axial current for this presentation

Analysis of electron scattering data

• p(e,e’p0)p• p(e,e’p+)n• both

Analysis of electron-proton scattering data

Purpose : Determine Q2 –dependence of vector coupling of p-N* : VpN*(Q2)

Data : * 1 p electroproduction

Database

* Empirical inclusive inelastic structure functions s T , sL Christy et al, PRC 81 (2010)

region where inclusives T & sL are fitted

Analysis resultQ2=0.40 (GeV/c)2

s T + e sL for W=1.1 – 1.68 GeV

p(e,e’p0)p p(e,e’p+)n


s T & sL (inclusive inelastic)

DCC

Christy et al PRC 81 s T

sL


For application to neutrino interactions

Analysis of electron scattering data

VpN*(Q2) & VnN*(Q2) fixed for several Q2 values

Parameterize VpN*(Q2) & VnN*(Q2) with simple analytic function of Q2

I=3/2 : VpN*(Q2) = VnN*(Q2) CC, NC

I=1/2 isovector part : ( VpN*(Q2) - VnN*(Q2) ) / 2 CC, NC

I=1/2 isoscalar part : ( VpN*(Q2) + VnN*(Q2) ) / 2 NC

DCC vector currents has been tested by data for whole kinematical region

relevant to neutrino interactions of En ≤ 2 GeV

Neutrino Results

Caveat

• Results presented here are still preliminary

• Careful examination needs to be made to obtain a final result

Cross section for nm N m- X

• pN & ppN are main channels in few-GeV region

• , hN KY cross sections are 10-1 – 10-2 smaller

nm n m- X nm p m- X

Comparison with nm N m- p N data

ANL Data : PRD 19, 2521 (1979)BNL Data : PRD 34, 2554 (1986)

DCC model prediction slightly undershoots data

• DCC model has flexibility to fit data (ANN*(Q2))• Data should be analyzed with nuclear effects

nm n m- p N nm p m-p+ p

Mechanisms for nm N m- p N

• (1232)D dominates for nm p m- p+ p (I=3/2) for En ≤ 2 GeV

• Non-resonant mechanisms contribute significantly

• Higher N*s becomes important towards En ≈ 2 GeV for nm n m- p N

nm n m- p N nm p m-p+ p

(1232)D (1232)D

d / s dW dQ2 ( ×10-38 cm2 / GeV2)

nm n m- p N nm n m- pp N nm p m-p+ p nm p m-pp N

En = 2 GeV

Conclusion

Development of DCC model for nN interaction in resonance region

• pN & ppN are main channels in few-GeV region

• DCC model prediction slightly undershoots data

• , D N*s, non-resonant are all important in few-GeV region (for nm n m- X )

essential to understand interference pattern among them

DCC model can do this; consistency between p interaction and axial current 　

Start with DCC model for , gN pN , , , , pN ppN hN KL KS

extension of vector current to Q2≠0 region, isospin separation

through analysis of e—- p & e—-’n’ data for W ≤ 2 GeV , Q2≤ 3 (GeV/c)2

Development of axial current for nN interaction; PCAC is maintained

Conclusion

Future development

• Axial form factor more neutrino data is ideal p N r N (t-ch p) (possible at J-PARC)

• ppN channel p N pp N experiment (J-PARC, K. Hicks et al.) g N pp N experiment (ELPH, JLab)

BACKUP

Physics at J-PARC: Charm, Neutrino, Strangeness, and Spin

T2K (Tokai to Kamioka) experiment for neutrino oscillation measurement

Far Detector (Super Kamiokande)

T2K measures neutrino fluxes at near and far detectors

J-PARC produces neutrino beam directed to Super Kamiokande by

Proton + nucleus p - (p + ) + ….

nm + m - (nm + m + )_

Neutrino oscillation

Expected nm fluxes in T2K

Near detectorFar detector

En (GeV)

n m survival probability (two-flavor case)

q : mixing angle

Dm2 (eV2) = m12 – m2

2

L (km) : distance between J-PARC and SK

E n (GeV) : neutrino energy

Comparing data to oscillation formula, mixing parameters (q , Dm2 ) can be determined

Comparing n data with n data leptonic CP violation ( dCP ) _

T2K

• Quasi-elastic (QE) is dominant

n-flux is measured by detecting QE

• 1 p production via -D excitation is major background

p can be absorbed QE is contaminated

nm

m-

𝜋nm

m-

D

LBNE and other planned experiments ( higher energy n-beam)

• DIS and higher nucleon resonances are main mechanisms

In this work, we focus on resonance region, single nucleon processes

basic ingredient for neutrino-nucleus interaction model


n

spNX is from our DCC model

via PCAC

nN l X ( X = , , , , pN ppN hN KL KS )

at forward limit Q2=0

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

pN

ppN KS

Formalism

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

q 0

Q20

CVC & PCAC

LSZ & smoothness

Finally spNX is from our DCC model

Results

SLpN

ppN KShN

KL

Prediction based on model well tested by data (first nN ppN)

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)

Agreement with SL (no PCAC) in D region

Comparison with Rein-Sehgal model

• Lower D peak of RS model

RS overestimate in higher energy regions (DCC model is tested by data) Similar findings by Leitner et al., PoS NUFACT08 (2008) 009

Graczyk et al., Phys.Rev. D77 (2008) 053001

Comparison in whole kinematical region will be done

after axial current model is developed

F2 from RS model

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)

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)

Eta production reactions


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, arXiv:1305.4351

Vector current (Q2=0) for h


Vector current (Q2=0) for K


Kamano, Nakamura, Lee, Sato, arXiv:1305.4351

Kamano, Nakamura, Lee, Sato, PRC 88 (2013)“N” resonances (I=1/2)

JP(L2I 2J)

Re(MR)

“Δ” resonances (I=3/2)

PDG: 4* & 3* states assigned by PDG2012AO : ANL-OsakaJ : Juelich (DCC) [EPJA49(2013)44, Model A]BG : Bonn-Gatchina (K-matrix) [EPJA48(2012)5]

-2Im(MR)(“width”)


s T + e sL for W=1.1 - 1.32 GeV




DCC


sL



s T + e sL for W=1.11 – 1.69 GeV




DCC


sL


Purpose : Vector coupling of neutron-N* and its Q2 –dependence : VnN*(Q2) (I=1/2)

I=3/2 part has been fixed by proton target data

Analysis of electron-’neutron’ scattering data

Data : * 1 p photoproduction (Q2=0)

* Empirical inclusive inelastic structure functions s T , sL (Q2≠0)

Christy and Bosted, PRC 77 (2010), 81 (2010)

Analysis resultQ2=0

ds / d W ( g n p-p) for W=1.1 – 2.0 GeV

Analysis result

Q2=1 (GeV/c)2

s T & sL (inclusive inelastic e—-’n’ ) DCC

Christy and Bosted PRC 77; 81

s T

sL

Q2=2 (GeV/c)2

sL

s T

Q2≠0

neutrino-induced meson productions satoshi nakamura osaka university, japan collaborators : h....

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