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Nuclear effects in neutrino-nucleus DIS

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Nuclear effects in neutrino-nucleus DIS

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Nuclear effects in neutrino-nucleus DIS

Shunzo Kumano

High Energy Accelerator Research Organization (KEK)

Graduate University for Advanced Studies (GUAS)

on behalf of

Masanori Hirai

Tokyo University of Science

in collaboration with Koichi Saito

Our nuclear PDF page: http://research.kek.jp/people/kumanos/nuclp.html

Sixth International Workshop on

Neutrino-Nucleus Interactions in the Few-GeV Region

May 18 - 22, 2009, Sitges, Barcelona, Spain

http://nuint09.ifae.es/

May 21, 2009

Contents

Introduction

• Motivations for nuclear structure functions in reactions

• Kinematics, Structure functions in deep inelastic scattering (DIS)

Nuclear modifications of PDFs

• Parton Distribution Functions (PDFs) in the nucleon

• Introduction to physics mechanisms for nuclear modifications

• Recent global analyses of nuclear PDFs

Kulagin, Petti; Eskola, Paukkunen, Salgado;

Schienbein, Yu, Keppel, Morfin, Olness, Owens;

Hirai, Kumano, Nagai; de Florian, Sassot

• Recent JLab measurements

3. Summary

Introduction

Motivations for nuclear structure functions in reactions

Basic interest to understand hadron structure,

Determination of fundamental constants

Perturbative & non-perturbative QCD

Understanding of nuclei in terms of quark and gluon degrees of freedom.

ResonanceDIS: Transition from hadron degrees of freedom to quark-gluon d.o.f.

Fundamental constants: s , sin2W

(2)Practical purposes for nuclear PDFs

Current DIS (Fe, Pb targets)

Nuclear corrections are important for extracting nucleonic PDFs.

Neutrino oscillation Nuclear effects in n + 16O

Other high-energy nuclear reactions

Quark-hadron matters, Cosmic-rays air shower, …

Kinematics of l+Nl’+X

z

valence-quark distributions

Neutrino-Nucleon Scattering: charged current (CC)

In parton model (leading order)

Recent neutrino DIS experiments

M. Tzanov et al. (NuTeV), PRD74 (2006) 012008.

Future: MINERnA (He, C, Fe, Pb), …

Nuclear Modifications

of

Parton Distribution Functions

Recent activities uncertainties NNLO QED s – s charm for LHC

Recent papers on unpolarized PDFs

It is likely that I miss some papers!

CTEQ(uncertainties) D. Stump (J. Pumplin) et al., Phys. Rev. D65 (2001) 14012 & 14013.

(CTEQ6) D. Pumplin et al., JHEP, 0207 (2002) 012; 0506 (2005) 080;

0602 (2006) 032; 0702 (2007) 053; PRD78 (2008) 013004.

(charm) PR D75 (2007) 054029;

(strange)PRL 93 (2004) 041802; Eur. Phys. J. C40 (2005) 145; JHEP 0704 (2007) 089.

GRV(GRV98) M. Glück, E. Reya, and A. Vogt, Eur. Phys. J. C5 (1998) 461.

(GJR08) M. Glück, P. Jimenez-Delgado, and E. Reya, Eur. Phys. J. C53 (2008) 355.

MRST A. D. Martin, R. G. Roberts, W. J. Stirling, and R. S. Thorne,

(MRST2001, 2002, 20033) Eur. Phys. J. C23 (2002) 73; Eur. Phys. J. C28 (2003) 455;

(theoretical errors) Eur. Phys. J. C35 (2004) 325;

(2004) PL B604 (2004) 61; (QED) Eur. Phys. J. C39 (2005) 155; PL B636 (2006) 259;

(2006) PRD73 (2006) 054019; PL B652 (2007) 292.

(2009)arXiv:0901.0002.

Alekhin S. I. Alekhin, PRD68 (2003) 014002; D74 (2006) 054033.

BB J. Blümlein and H. Böttcher, Nucl. Phys. B774 (2007) 182-207.

NNPDF S. Forte et al., JHEP 0205 (2002) 062; 0503 (2005) 080; 0703 (2007) 039.

H1 C. Adloff et al., Eur. Phys. J. C 21 (2001) 33; C30 (2003) 1.

ZEUS S. Chekanov et al., PRD67 (2003) 012007; Eur. Phys. J. C42 (2005) 1.

Recent upgrades

Parton Distribution Functions (PDFs) in the nucleon

http://durpdg.dur.ac.uk/hepdata/pdf.html

A. D. Martin, W. J. Stirling,

R. S. Thorne, G. Watt,

arXiv: 0901.0002.

Introduction toPhysics Mechanismsfor Nuclear Modifications

1.2

EMC

NMC

1.1

E139

E665

1

0.9

0.8

0.7

0.001

0.01

0.1

1

Shadowing

(qq fluctuation of photon)

Nuclear modifications of structure function F2

Anti-shadowing

Fermi motion

of the nucleon

For a review, see

D. F. Geesaman, K. Saito,

A. W. Thomas,

Ann. Rev. Nucl. Part. Sci.

45 (1995)337.

x

Nuclear binding

(+ Nucleon modification)

Binding and Fermi motion

0.98

0.20

Because the peak shifts slightly (1 0.98),

nuclear modification of F2 is created.

Fermi motion

binding

Shadowing

SK, Phys. Rept. 303 (1998) 183

A typical multi-scattering model

W. Melnitchouk and A. W. Thomas,

PRD 47 (1993) 3783.

Double scattering part

Vector meson dominance

Pomeron exchange

Meson (Reggeon) exchange

- Interference between Pomeron and Reggeon
- Anti-shadowing ? (Brodsky and Lu, 1990)

Determination of Nuclear Parton Distribution Functions

Recent global analyses on nuclear PDFs

- EPS09
- K. J. Eskola, H. Paukkunen, and C. A. Salgado, JHEP 04 (2009) 065.
- Charged-lepton DIS, DY, p0 production in dAu.

- SYKMOO08
- I. Schienbein, J. Y. Yu, C. Keppel, J. G. Morfin, F. I. Olness,
and J. F. Owens, Phys. Rev. D 77 (2008) 044013.

- Neutrino DIS (only NuTeV data).

- I. Schienbein, J. Y. Yu, C. Keppel, J. G. Morfin, F. I. Olness,
- HKN07
- M. Hirai, S. Kumano, and T. -H. Nagai, Phys. Rev. C 76 (2007) 065207.
- Charged-lepton DIS, DY.

- DS04
- D. de Florian and R. Sassot, Phys. Rev. D 69 (2004) 074028.
- Charged-lepton DIS, DY.

See also S. A. Kulagin and R. Petti, Phys. Rev. D 76 (2007) 094023;

L. Frankfurt, V. Guzey, and M. Strikman, Phys. Rev. D 71 (2005) 054001.

Kulagin and Petti’s analysis

S. A. Kulagin and R. Petti, Phys. Rev. D76 (2007) 094023.

• Although most global analyses assume rather a model-independent functional form

with a number of parameters, their approach is different in the sense that

only the “off-shell” effects in the nucleon are parametrized.

• They tried to obtain structure functions rather than the PDFs.

Nuclear structure functions

= Conventional nuclear physics + Nucleon modifications in nuclear medium

= Binding, Fermi motion + Pion excess + Shadowing (Multiple scattering)

+ Off-shell effects (with parameters to be determined from data)

FMB: Fermi Motion + Binding

OS: +Off-Sell

PI: +Pion

NS: +Nuclear Shadowing

Global nuclear PDF analysis

Data set for nuclear PDF analyses

HKN07, PRC 76

(2007) 065207.

• Charged-lepton DIS, DY

0.005 < x < 0.8, 1 < Q2 < 113 GeV2

• p0 production from d-Au collision

• Neutrino DIS (NuTeV/CCFR): 0.015 < x < 0.75

Analysis results: total c2 / d.o.f. (# of parameter)

- EPS09: 0.80 (17)
- HKN07: 1.21 (12)
- DS06: 0.80 (18)
- SYKMOO08-A: 1.37 [n data]

JLab

- Factory
MINARA

HKN07 results

and future experiments

Fermilab

J-PARC

RHIC

LHC

eLIC

eRHIC

HKN07, PRC 76 (2007) 065207.

Fermilab

J-PARC

GSI

RHIC

LHC

eLIC

eRHIC

EPS09

HKN07

Valence

Sea

Gluon

DS04

Comparison of nuclear PDFs

Different analysis results are consistent with each other

because they are roughly within uncertainty bands.

Valence quark: Well determined except at small x.

Antiquark: Determined at small x, Large uncertainties at medium and large x.

Gluon: Large uncertainties in the whole-x region.

EPS09 (K. J. Eskola et al.), JHEP 04 (2009) 065

SYKMOO-08 (I. Schienbein et al.),

PRD 77 (2008) 054013

Analysis of SYKMOO-08 (Schienbein et al.)

Charged-lepton scattering

Differences

from typical NPDFs.

Base-1 • remove CCFR data

• incorporate deuteron corrections

Base-2 corresponds to CTEQ6.1M with s≠sbar

• include CCFR data

Charged-lepton correction factors are applied.

• s≠sbar

Neutrino scattering

Base-2: Using current nucleonic PDFs,

they (and MRST) obtained very different

corrections from charged-lepton data.

Base-1: However, it depends on the analysis method for determining “nucleonic” PDFs.

HKN07

MRSTW-08 analysis

D. Martin, W. J. Stirling, R. S. Thorne,

G. Watt, arXiv: 0901.0002.

MRST98 nuclear correction

DS04

DS04*NUCMOD(x)

Deviations at large x:

Same tendency as the Schienbein et al.’s.

Recent measurements at JLab

J. Seely et al., arXiv: 0904.4448

Results indicate that nuclear modifications

may not be described by usual A (and density)

dependence for light nuclei.

Summary

Global analyses: Different results are roughly consistent with each other.

Valence quark: Well determined except at small x.

Antiquark: Determined at small x, Large uncertainties at medium and large x.

Gluon: Large uncertainties in the whole-x region.

Schienbein et al.’s analysis of neutrino-Fe data in 2008

Differences from SLAC measurements and parametrizations!?

Neutrino oscillation

1. Studies of resonance DIS

Transition from hadron degrees of freedom to quark-gluon.

2. Nuclear corrections in n + 16O

Future n experiments

1. MINERnA Nuclear corrections in F3

2. Neutrino factory: Proton and deuteron targets instead of Fe and Pb.

“Correct” valence-quark distributions in “the nucleon”.

The End

The End