High-Energy Hadron PhysicsHigh-Energy Hadron Physicsat J-PARC at J-PARC
Shunzo KumanoShunzo Kumano
High 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)
[email protected]@kek.jp
http://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.
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
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=200GeVLHC: s=14TeV
• s = (p1 + p2 )2
• mμμ ≥ 3 GeV
e.g. Drell-Yan: x1x2 =mμμ
2
s
x :
mμμ2
s
x :mμμ
2
s≥
310
=0.3J-PARC
≥3200
=0.02RHIC
≥3
14000=0.0002LHC
Large-x facility(Medium-x)
Small-x facility
Hadron facilitiesHadron facilities
p + p(A)→ μ+μ−+ X(qq→ μ+μ−)
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 ≡lnN
Mellin transformation: dx0
1
∫ xN−1F (x)
Large contributions come fromthe partonic threshold region
z =Mμμ
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
τdσ
dτ dφ:
dxa
xaτ
1
∫a,b∑
dxb
xbτ / xa
1
∫ fa (xa , μ 2 ) fb (xb , μ 2 )ωab (z, Mμμ2 / μ 2 ,α s )
τ =Mμμ2 / s, z = τ / (xaxb ) = Mμμ
2 / se.g. in transverse spin asymmetry
ω ab(z,Mμμ2 / μ 2 ,α s) =ω qq
(0)(z) +α s
πω qq
(1)(z,Mμμ2 / μ 2 ) + ⋅⋅⋅
ω qq(1)(z,Mμμ
2 / μ 2 ) =CF 4zln(1−z)1−z
⎛⎝⎜
⎞⎠⎟+
+⋅⋅⋅⎡
⎣⎢
⎤
⎦⎥
note:largecontributionfromtheregionz→ 1
dσ N
dφ: f N
f∑ (μ 2 ) f N (μ 2 )ω N (Mμμ
2 / μ 2 ,α s)
ω qq(1)N (Mμμ
2 / μ 2 ) = CF 2 ln2 (Neγ E ) + ⋅⋅⋅⎡⎣ ⎤⎦A large term at z → 1correspondstoalargetermintheMellinspaceatN→ ∞.
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 sL2 α sL
α sk L2k α s
k L2k −1
. . .
. . .
. . .
. . .
pQCD corrections are shown by σ
σ LeadingOrder(LO)
asafunctionofthedimuonmassMμ+μ−
.
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
Dif
fere
nce
bet
wee
n t
heo
ry a
nd
exp
erim
ent
(importance of accurate PDFs)
CDF experiment: PRL, 77 (1996) 438.
p + p→ jet+ X
s =1.8TeV,ETjet =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 PDF
CTEQ6
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.
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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
LO
NLO
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
06AAC
GRSV
BB
LSS
-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
06AAC
GRSV
BB
LSS
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 ∝ dσ
g1 ∝ dσ ↑,+1( )−dσ ↑,−1( )
b1 ∝ dσ 0( )−dσ +1( ) +dσ −1( )
2
q↑H x,Q2( )⎡⎣ ⎤⎦
F1 =12
ei2
i∑ qi +qi( )
qi =13
qi+1 +qi
0 +qi−1( )
g1 =12
ei2 Δqi + Δqi( )∑ Δqi = qi↑
+1 − qi↓+1
b1 =12
ei2 δqi +δqi( )
i∑ δqi = 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→ μ+μ− + X
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
γp → π +n H. Gao
s7 dσdt
Transition from hadron degrees of freedomto quark-gluon d.o.f.
Constituent counting rule
dσdt
(AB→ CD) : s2−n f(θc.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 =σ A
AσN
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 505000
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
ξ = p+ − ′p +
p+ + ′p + =−Δ+
2P+
t =Δ2
dz−
4π∫ eixP+z− ′p (−z / 2)γ + (z / 2) p
z+=0, rz⊥=0=
12P+ H(x,ξ,t)u( ′p )γ +u(p) + E(x,ξ,t)u( ′p )
iσ +αΔα
2Mu(p)
⎡
⎣⎢
⎤
⎦⎥
dz−
4π∫ eixP+z− ′p (−z / 2)γ +γ5 (z / 2) p
z+=0, rz⊥=0=
12P+
%H(x,ξ,t)u( ′p )γ +γ5u(p) + %E(x,ξ,t)u( ′p )γ5Δ
+
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
γγ ** γγ
Forward limit: PDFs H(x,ξ,t) ξ=t=0 = f (x), %H(x,ξ,t)
ξ=t=0=Δf (x)
There is no analog in E and %E.First moments: Form factors
dx H(x,ξ,t)∫ =F1(t), dxE(x,ξ,t)∫ =F2 (t)
dx %H(x,ξ,t)∫ =GA(t), dx %E(x,ξ,t)∫ =GP (t)
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
dxx Hq(x,ξ,t=0)+ Eq(x,ξ,t=0)⎡⎣ ⎤⎦∫ ,J q =12Δq+ Lq
Emission of quark with momentum fraction x+ξEmission of antiquark with momentum fraction ξ-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.
π
p
p
Bp GPDs
t ? mN2
Meson distribution amplitudeQuark distributionAntiquark distribution
xξ − xξ− − x ξ+ xξ − x ξ+ x ξ−
1− ξ− ξ0 1
x −ξ < x< ξ −1< x< ξ ξ < x<1
(I)(I)
(II)(II)
NN
γγ ** ππ
NN
In lepton scatteringIn lepton scattering
NN
γγ ** ππ (other hadron)(other hadron)
NN
At J-PARCAt J-PARC (→ μ+μ−)
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
gluon
u quark
c quark b quark
Q2=2GeV2
Q2=2GeV2 Q2=2GeV2
Q2=10GeV2 Q2=100GeV2
KKPAKK Kretzer
HKNS
s quark
DSS
Fragmentation functionsFragmentation functionsat J-PARCat J-PARC
s =xaxbs~(0.4)2 (10GeV)2
s =0.4 ⋅10 =4GeV
z~pT
s / 2=
pT
2~1(largez)
ss
J-PARCJ-PARC
Gluon and light-quark fragmentation functions have large uncertainties.
Global analysisresults for π(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 1
2(uu + dd)
(2)strangemeson,ss
(3)tetraquark(KK),12(uuss + ddss)
(4)glueballgg
Contradicts with experimental widths
Γtheo( f0 → ππ) =500 −1000MeV? Γexp =40 −100MeV
Γtheo( f0 → γγ) =1.3−1.8keV? Γexp =0.205keV
Contradicts with lattice-QCD estimate
mlattice( f0 ) =1600MeV? mexp =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