High-Energy Hadron PhysicsHigh-Energy Hadron Physicsat J-PARC at J-PARC

Shunzo KumanoShunzo KumanoHigh Energy Accelerator Research Organization (KEK) High Energy Accelerator Research Organization (KEK)

Graduate University for Advanced Studies (GUAS)Graduate University for Advanced Studies (GUAS)

September 1 – 2, 2008 September 1 – 2, 2008 (Talk on Sept. 2)(Talk on Sept. 2)

shunzo.kumano@kek.jpshunzo.kumano@kek.jphttp://research.kek.jp/people/kumanos/http://research.kek.jp/people/kumanos/

研究会「研究会「 J-PARCJ-PARC ハドロン物理の将来計画を考える」ハドロン物理の将来計画を考える」和光市　理化学研究所和光市　理化学研究所

Haron Physics at J-PARCHaron Physics at J-PARC

Strangeness nuclear physics (1st experiment)

Exotic hadrons

Hadrons in nuclear medium

Hard processes (50 GeV recovery)

Nucleon spin (proton polarization)

Quark-hadron matter (heavy ion)Need m

ajor

upgra

des

Next p

rojec

t

s

1st p

rojec

t

(also

)

My talk is related to

Kaon and pion beams

Proton beam

= Feasibility studies are not enough or proposals are not approved.

High-Momentum Beam Line High-Momentum Beam Line (30, 50 GeV Proton)(30, 50 GeV Proton)

ContentsContents

1.1. Motivations and issuesMotivations and issues

2.2. Possible topicsPossible topics (other than Goto’s and Tanaka’s explanations)(other than Goto’s and Tanaka’s explanations)

3. Summary3. Summary

Motivations and IssuesMotivations and Issues

From “From “strangenessstrangeness nuclear physics”nuclear physics” to “to “charmcharm nuclear physics” nuclear physics”

J-PARC is a facility to create new states of J-PARC is a facility to create new states of hadrons by extending flavor degrees of freedom.hadrons by extending flavor degrees of freedom.

First experiments: K, First experiments: K, , , , , , … , … (many theoretical studies)(many theoretical studies)

Future experiments: why not J/Future experiments: why not J/, D, …, , D, …, new “tetra-quark-like” hadronew “tetra-quark-like” hadronsns (not so well studied?)(not so well studied?)

One of possible topics with 30 – 50 GeV proton beaOne of possible topics with 30 – 50 GeV proton beam m

J-PARC: 30 GeV → s=8GeV

Comments on Structure Functions IComments on Structure Functions I

Advantages

Studies of a different x region (large x) from the ones at RHIC and LHC (If the primary proton beam is polarized, there is no rival facility in the world for studying spin structure.)

Different observables, e.g. antiquark and gluon, from measurements at JLab (which is also a large-x facility)

Next two transparencies for explanations

…

x1 x2

J-PARC: s =10GeVRHIC: s=200GeVHC: s=14TeV

• s = (p1 + p2 )2

• mμμ ≥ 3 GeV

e.g. Drell-Yan: x1x2 =m mm

2

s

x :

mmm2

s

x :mmm

2

s≥

310

=0.3J-PARC

≥3200

=0.02RHIC

≥3

14000=0.0002HC

Large-x facility(Medium-x)

Small-x facility

Hadron facilitiesHadron facilities

p + p(A)→ m+m−+ (qq → m+m−)

Flavor asymmetric antiquark distributions: u / d Flavor asymmetric antiquark distributions: u / d

J-PARC proposal (P24), M. Bai et al. (2007)

http://www.acuonline.edu/academics/cas/physics/research/e906.html

E866

E906

J-PARC

This project is suitable for probing “peripheral structure” of the nucleon.

この領域での物理的意義を理論的に検討しておく

Comments on Structure Functions IIComments on Structure Functions II

Advantage and / or disadvantage:

Perturbative QCD corrections are large.

Interesting for pQCD physicists

Can we obtain reliable parton distribution functions from measured cross sections?

Applicability of perturbative QCDApplicability of perturbative QCDCross section = pQCD non-pQCD “hadron structure” (PDFs)

In order to extract the hadron-structure part,pQCD should be understood.

resu

mm

atio

nre

sum

mat

ion

fixed orderfixed order

LOLO

NLONLO

NNkkLOLO

LLLL NLLNLL

1

α sL2 α sL

α sk L2k α s

k L2k −1

. . .

. . .

. . .

. . .

L ≡lN

Mellin transformation: dx0

1

∫ xN−1F(x)

Large contributions come fromthe partonic threshold region

z =Mmm

2

s: 1.

Soft-gluon resummation is needed.Soft-gluon resummation is needed.Drell-Yan cross sectionDrell-Yan cross section

Ref. H. Shimizu Ref. H. Shimizu et al.et al., PRD 71 (2005) 114007, PRD 71 (2005) 114007

τdσdτ dφ

:dxa

xaτ

1∫

a,b∑ dxb

xbτ /xa

1∫ fa (xa , μ 2 ) fb (xb , μ 2 )ωab (z, Mμμ

2 / μ 2 ,α s )τ =Mμμ

2 / s, z = τ / (xaxb ) = Mμμ2 / s

e.g. in transverse spin asymmetry

ω αb(z,Mmm2 / m 2 ,αs)=ω qq

(0)(z)+αs

pω qq

(1)(z,Mmm2 / m 2 )+ ⋅⋅⋅

ω qq(1)(z,Mmm

2 / m 2 )=CF 4zl(1−z)1−z

⎛⎝⎜

⎞⎠⎟+

+⋅⋅⋅⎡⎣⎢

⎤⎦⎥

oτe:lαrgecoτribuτiofrom τheregioz→ 1

ds N

dφ: fN

f∑ (m 2 )fN (m 2 )ω N(Mmm

2 / m 2 ,αs)

ω qq(1)N (Mμμ

2 / μ 2 ) = CF 2 ln2 (Neγ E ) + ⋅⋅⋅⎡⎣ ⎤⎦A large term at z → 1correspodsτoαlαrgeτerm iτheMellispαceατN → ∞.

Applicability of perturbative QCD in Drell-YanApplicability of perturbative QCD in Drell-YanYokoya@High-energy J-PARCYokoya@High-energy J-PARChttp://www-conf.kek.jp/hadron08/hehp-jparc/ • • Higher-order Higher-order ααss corrections corrections

• • ResummationsResummations

Higher-order corrections are large at J-PARC (50 GeV);Higher-order corrections are large at J-PARC (50 GeV);however, the pQCD terms could be under control.however, the pQCD terms could be under control.

resu

mm

atio

nre

sum

mat

ion

fixed orderfixed order

LOLO

NLONLO

NNkkLOLO

LLLL NLLNLL

1

α s L2 α sL

α sk L2k α s

k L2k −1

. . .

. . .

. . .

. . .

pQCD corrections are shown by s

s eαdigOrder(O)

αsαfucτioofτhedim uom αssMm+m− .

Motivations and Issues:

Why do you need such detailed nucleon structure? For example, the nucleon spin is one of fundamental physical quantities, but it is not understood. In order to understand it, we need measurements from small x (RHIC, (LHC)) to large x (JLab, J-PARC).

Costs for beamline and 50-GeV recovery (nothing to do with physics)

…

Comments on Structure Functions IIIComments on Structure Functions III

Motivations and Issues:

Research purposes, Slogans for general public or at least for researchers in neighboring fields Applications Justifiable In calculating any hard interactions with a hadron, parton distribution functions are needed. New physics (e.g. subquark, properties of quark-hadron matters, …) at RHIC and LHC. Possibly also to Ultra-high energy cosmic rays (~1020 eV) “High-energy nuclear physics at EeV and ZeV”

Fundamentals Nucleon spin, Confinement mechanism, … Appealing slogan(s)? … (Ideas of young people?)

Comments on Structure Functions IVComments on Structure Functions IV

Quark substructure?Quark substructure?

Could be explained without substructure

Jet transverse energy

Diff

eren

ce b

etw

een

theo

ry a

nd e

xper

imen

t

(importance of accurate PDFs)

CDF experiment: PRL, 77 (1996) 438.

p + p→ φeτ+

s =1.8TeV ,ETφeτ =15 −400GeV

Comparison of theoretical calculationswith CDF experimental data.

Subquark signature ???

LHC でも同様なことが起こる可能性あり。

PDF uncertaintyPDF uncertainty

CTEQ5M1

MRS2001

CTEQ5HJ

CTEQ6 (J. Pumplin et al.), JHEP 0207 (2002) 012

u d

g

other PDFCTEQ6

Important x region for finding an “exotic event” in a high-pT region at LHC

J-PARC x region

If processes are well understood theoreticallyIf processes are well understood theoreticallyincluding pQCD terms, J-PARC measurementsincluding pQCD terms, J-PARC measurementsare important for finding new physics at LHCare important for finding new physics at LHCor possibly in cosmic rays.or possibly in cosmic rays.

High-energy cosmic ray interactions High-energy cosmic ray interactions

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ǙDZÇÃÉsÉNÉ`ÉÉÇ å©ÇÈÇΩÇflÇ…ÇÕïKóvÇ≈Ç∑ÅB

p, …, Fe N, O

• • Small Small xx for atmospheric nuclei (N, O) for atmospheric nuclei (N, O)• • Large Large xx for cosmic-ray nuclei (p, …, Fe) for cosmic-ray nuclei (p, …, Fe)

Most energetic particles (namely, at large Most energetic particles (namely, at large xxF F ))contribute mainly to subsequent shower developmencontribute mainly to subsequent shower developmen

t.t.

( R. Engel)

High-energy hadronic interactionsHigh-energy hadronic interactionsand their effects on cosmic-ray physics.and their effects on cosmic-ray physics.

QuickTime˛ Ç∆ êLí£ÉvÉçÉOÉâÉÄ

ǙDZÇÃÉsÉNÉ`ÉÉÇ å©ÇÈÇΩÇflÇ…ÇÕïKóvÇ≈Ç∑ÅB

LHC

J-PARC

HERARHIC

Ultra-high energy cosmic raysare related to small-x physics (LHC)and large-x physics (JLab, J-PARC).

High-energy hadron facilities and high-energy cosmic rays High-energy hadron facilities and high-energy cosmic rays

( R. Engel, 2005)

Possible TopicsPossible Topics(other than Goto’s and Tanaka’s explanations)(other than Goto’s and Tanaka’s explanations)

Results & Future experiments

0.4

0.6

0.8

1

1.2

0.001 0.01 0.1 1

x

LONLO

uv

Q 2 = 1 GeV 2

JLab

FactoryMINARA

0.4

0.6

0.8

1

1.2

0.4

0.6

0.8

1

1.2

0.001 0.01 0.1 1

x

q

gluon

FermilabJ-PARC

RHICLHC

RHICLHC

FermilabJ-PARCGSI

eLICeRHIC

eLICeRHIC

E866

E906

J-PARC

J-PARC proposalJ. Chiba et al. (2006)

(HKN07)(HKN07)

Situation of polarized PDFsSituation of polarized PDFs Gluon and antiquark distributions have large uncertainties at large x.

-0.2

0

0.2

0.4

0.6

0.001 0.01 0.1 1

AAC06

GRV

BB

-0.04

-0.03

-0.02

-0.01

0

0.01

0.001 0.01 0.1 1

x

x Δ g( x )

Q

2

=1GeV

2

x Δ q( x )

J-PARC

0

0.1

0.2

0.3

0.4

0.5

0.001 0.01 0.1 1

-0.2

-0.1

0

0.001 0.01 0.1 1

x

AAC06

GRV

BB

x Δ u

v

( x )

x Δ d

v

( x )

Q

2

=1GeV

2

Structure functionsStructure functions(in e scattering)(in e scattering)

Parton modelParton model

F1 ∝ ds

g1 ∝ ds ↑,+1( )−ds ↑,−1( )

b1 ∝ ds 0( )−ds +1( )+ ds −1( )

2

q↑H x,Q2( )⎡⎣ ⎤⎦ F1 =

12

ei2

i∑ qi + qi( )

qi =13qi

+1 + qi0 + qi

−1( )g1 =

12

ei2 Δqi + Δqi( )∑ Δqi = qi↑

+1 − qi↓+1

b1 =12

ei2 dqi +dqi( )

i∑ dqi = qi

0 −qi

+1 + qi−1

2

Tensor structure at high energies Tensor structure at high energies (Note: No polarized proton beam is needed!)(Note: No polarized proton beam is needed!)

1st measurement of b1:(HERMES) A. Airapetian et al., PRL 95 (2005) 242001.

J-PARC p +

rd → m+m− +

予想に反する陽子のスピン構造 テンソル構造は？

偏極スピン１粒子中の偏極スピン１粒子中の「非偏極」クォーク分布「非偏極」クォーク分布

Elastic Scattering: A+B Elastic Scattering: A+B C+D at large p C+D at large pTT

L.Y. Zhu et al., PRL 91 (2003) 022003

gp → π +n H. Gao

s7 dsdτ

Transition from hadron degrees of freedomto quark-gluon d.o.f.

Constituent counting rule

dsdτ

(AB→ CΔ ) : s2− f(qc.m .)

n = nA + nB + nC + cD

(total number of interacting elementary particles)

J-PARC: p + p p + p

Color TransparencyColor Transparency

Investigate pInvestigate p AA pp pp (A-1)(A-1)

At large momentum transfer, a small-size component of the hadron At large momentum transfer, a small-size component of the hadron wave function should dominate. This small-size hadron could freely wave function should dominate. This small-size hadron could freely pass through nuclear medium. pass through nuclear medium. (Transparent)(Transparent)

Nuclear transparency: T =sA

AsN

Hadron size ~ 1 / hard scale

Color transparency: T larger, as the hard scale larger

(BNL-EVA) J. Aclander et al., (BNL-EVA) J. Aclander et al., PRC 70 (2004) 015208PRC 70 (2004) 015208

““Probe of dynamics of elementary reactions”Probe of dynamics of elementary reactions”

Possibility at J-PARC

Incident energy (GeV)Incident energy (GeV)1010 3030 5050

00

0.40.4

0.80.81212CC

(p,2p) at J-PARC

T

Generalized Parton Distributions (GPDs)Generalized Parton Distributions (GPDs)GPDs are defined as correlatioGPDs are defined as correlationnof off-forward matrix.of off-forward matrix.

Bjorken variable

Momentum transfer squared

x =

p+ − ′p +

p+ + ′p + =−Δ+

2P+

t =Δ2

dz−

4p∫ eixP

+z− ′p (−z / 2)g + (z / 2) pz+=0,rz⊥=0

=1

2P+ H(x,x,τ)u( ′p )g +u(p)+ E(x,x,τ)u( ′p )is +αΔα

2Mu(p)

⎡⎣⎢

⎤⎦⎥

dz−

4p∫ eixP

+z− ′p (−z / 2)g +g5 (z / 2) pz+=0,rz⊥=0

=1

2P+%H(x,x,τ)u( ′p )g +g5u(p)+ %E(x,x,τ)u( ′p )

g5Δ+

2Mu(p)

⎡⎣⎢

⎤⎦⎥

x =

Q2

2p⋅q

Skewdness parameter

P =

p+ ′p2

,Δ = ′p −p

pp′′= p= p ++ΔΔpp

kk

qq qq ––ΔΔk+qk+q

kk ++ΔΔ

tt == ΔΔ 22

gg ** gg

Forward limit: PDFs H(x,x,τ)

x=τ=0 = f(x), %H(x,x,τ)x=τ=0

=Δf(x)

There is no analog in E and %E.First moments: Form factorsdx H(x,x,τ)∫ =F1(τ), dx E(x,x,τ)∫ =F2(τ)

dx %H(x,x,τ)∫ =GA(τ), dx %E(x,x,τ)∫ =GP(τ)

Dirac and Pauli form factors Dirac and Pauli form factors FF1 , 1 , FF22

Axial and Pseudoscalar form factors Axial and Pseudoscalar form factors GGA A , , GGPP

Second moments: Angular momentaSum rule: Jq =

12

dx x Hq(x,x,τ=0)+ Eq(x,x,τ=0)⎡⎣ ⎤⎦∫ ,Jq =12Δq + q

Emission of quark with momentum fraction x+xEmission of antiquark with momentum fraction x-x

GPDs at J-PARCGPDs at J-PARC

GPDs at J-PARC:GPDs at J-PARC:SK, M. Strikman, K. Sudoh, SK, M. Strikman, K. Sudoh, in progress.in progress.

p

p

p

Bp GPDs

qq

t ? mN2

Meson distribution amplitudeQuark distributionAntiquark distribution

xx − xx− − x x+ xx − x x+ x x−

1− x− x0 1

x −x < x < x −1< x < x x < x <1

(I)(I)

(II)(II)

NN

gg ** pp

NN

In lepton scatteringIn lepton scattering

NN

gg ** pp (other hadron)(other hadron)

NN

At J-PARCAt J-PARC (→ m+m−)

E. R. Berger, M. Diehl, B. Pire, E. R. Berger, M. Diehl, B. Pire, PRL B523 (2001) 265.PRL B523 (2001) 265.

Short-range NN interactionShort-range NN interaction • • Short-range repulsive core, Tensor forceShort-range repulsive core, Tensor force • • Quark degrees of freedomQuark degrees of freedom • • Cold dense nuclear matter, Neutron starCold dense nuclear matter, Neutron star

Ciofi degli Atti@J-PARC-NP07Ciofi degli Atti@J-PARC-NP07

E. Piasetzky et al.,E. Piasetzky et al.,PRL97 (2006) 162504PRL97 (2006) 162504

Strikman@INPC07Strikman@INPC07

Nuclei do not collapse Nuclei do not collapse Short-range repulsive core Short-range repulsive corerr

V(r)V(r)

Nucleon size r ≈ 0.8 fmNucleon size r ≈ 0.8 fmAverage nucleon separation in a nucleus: R ≈ 2 fm ~ 2rAverage nucleon separation in a nucleus: R ≈ 2 fm ~ 2rThe short-range part is important as the density becomes largerThe short-range part is important as the density becomes larger (neutron star).(neutron star).

0.4 fm0.4 fm

A(p, 2pN)X experiment for short range correlationA(p, 2pN)X experiment for short range correlation

initialinitial finalfinal

pp nn

pp

pp

-0.5

0

0.5

1

1.5

-0.5

0

0.5

1

1.5

-0.5

0

0.5

1

1.5

-0.5

0

0.5

1

1.5

0 0.2 0.4 0.6 0.8 1z

-0.5

0

0.5

1

1.5

0 0.2 0.4 0.6 0.8 1z

gluo

uquαrk

cquαrk bquαrk

Q2=2GeV2

Q2=2GeV2 Q2=2GeV2

Q2=10GeV2 Q2=100GeV2

KKPAKK Kreτzer

HKN

squαrk

Δ

Fragmentation functionsFragmentation functionsat J-PARCat J-PARC

s =xαxbs~(0.4)2(10GeV )2

s=0.4 ⋅10 =4GeV

z ~pTs / 2

=pT2

~1(lαrgez)

ss

J-PARCJ-PARC

Gluon and light-quark fragmentation functions have large uncertainties.

Global analysisresults for p(HKNS07)

Large differences between the functions of various analysis groups.

Criteria for determining Criteria for determining ff00 structure structure by its fragmentation functionsby its fragmentation functionsPossible configurations of f0 (980)

(1) ordinary u,d - meson 12

(uu + dd )

(2)sτrαgem eso,ss

(3)τeτrαquαrk(KK),12(uuss+ ddss)

(4)gluebαllgg

Contradicts with experimental widthsGτheo(f0 → pp)=500 −1000MeV? Gexp =40 −100MeV

Gτheo(f0 → gg)=1.3−1.8keV ? Gexp =0.205keV

Contradicts with lattice-QCD estimatemlattice ( f0 ) =1600MeV? m exp =980MeV

Discuss 2nd moments and functional forms (peak positionDiscuss 2nd moments and functional forms (peak positions)s)of the fragmentation functions for of the fragmentation functions for ff00 by assuming by assumingthe above configurations, (1), (2), (3), and (4).the above configurations, (1), (2), (3), and (4).

M. Hirai, SK, M. Oka, K. Sudoh, M. Hirai, SK, M. Oka, K. Sudoh, PRD 77 (2008) 017504.PRD 77 (2008) 017504.

SummarySummaryThere are interesting topics which could be investigated by usinThere are interesting topics which could be investigated by using g the primary 30-50 GeV proton beam. the primary 30-50 GeV proton beam. • • Structure functions, spin physics, parton-energy loss, …Structure functions, spin physics, parton-energy loss, … (talks by Goto and Tanaka)(talks by Goto and Tanaka) • • Charm nuclear physicsCharm nuclear physics • • Large-Large-xx part of parton distribution functions part of parton distribution functions • • Perturbative QCDPerturbative QCD • • Tensor structure at high energyTensor structure at high energy • • Exotic hadron search by fragmentationsExotic hadron search by fragmentations • • Transition from quark to hadron degrees of freedomTransition from quark to hadron degrees of freedom • • Short-range nuclear force Short-range nuclear force • • Color transparencyColor transparency • • Generalized parton distributionsGeneralized parton distributions

Need theoretical ideas and experimental feasibility studies•Need theoretical ideas and experimental feasibility studies• • • attractive slogan(s) and PR to the public attractive slogan(s) and PR to the public

The End

The End