1. High-Energy Hadron Physics at J-PARC Shunzo Kumano High Energy Accelerator Research Organization (KEK) Graduate University for Advanced Studies (GUAS) September 1 – 2, 2008 (Talk on Sept. 2) shunzo.kumano@kek.jphttp://research.kek.jp/people/kumanos/ 研究会「 J-PARC ハドロン物理の将来計画を考える」 和光市 理化学研究所

2. Haron 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 major upgrades Next projects 1st project (also ) My talk is related to Kaon and pion beams Proton beam              = Feasibility studies are not enough or proposals are not approved.

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

4. Contents 1.Motivations and issues 2.Possible topics (other than Goto’s and Tanaka’s explanations) (other than Goto’s and Tanaka’s explanations) 3. Summary

5. Motivations and Issues

6. From “strangeness nuclear physics” to “charm nuclear physics” to “charm nuclear physics” J-PARC is a facility to create new states of hadrons by extending flavor degrees of freedom. First experiments: K, , , , … (many theoretical studies) (many theoretical studies) Future experiments: why not J/ , D, …, new “tetra-quark-like” hadrons new “tetra-quark-like” hadrons (not so well studied?) (not so well studied?) One of possible topics with 30 – 50 GeV proton beam

7. Comments 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  …

8. Large-x facility (Medium-x) Small-x facility Hadron facilities

9. 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

10. Comments 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?

11. Applicability of perturbative QCD Cross section = pQCD  non-pQCD “hadron structure” (PDFs) In order to extract the hadron-structure part, pQCD should be understood. resummation fixed order LO NLO N k LO LLNLL... Soft-gluon resummation is needed. Drell-Yan cross section Ref. H. Shimizu et al., PRD 71 (2005) 114007

12. Applicability of perturbative QCD in Drell-Yan Yokoya@High-energy J-PARC http://www-conf.kek.jp/hadron08/hehp-jparc/ Higher-order  s corrections Higher-order  s corrections Resummations Resummations Higher-order corrections are large at J-PARC (50 GeV); however, the pQCD terms could be under control. resummation fixed order LO NLO N k LO LLNLL...

13. 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 III

14. 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 (~10 20 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 IV

15. Quark substructure? Could be explained without substructure Jet transverse energy Difference between theory and experiment (importance of accurate PDFs) CDF experiment: PRL, 77 (1996) 438. Comparison of theoretical calculations with CDF experimental data. Subquark signature ??? LHC でも同様なことが起こる 可能性あり。

16. PDF uncertainty CTEQ5M1 MRS2001 CTEQ5HJ CTEQ6 (J. Pumplin et al.), JHEP 0207 (2002) 012 ud g Important x region for finding an “exotic event” in a high-p T region at LHC J-PARC x region If processes are well understood theoretically including pQCD terms, J-PARC measurements are important for finding new physics at LHC or possibly in cosmic rays.

17. High-energy cosmic ray interactions p, …, Fe N, O Small x for atmospheric nuclei (N, O) Small x for atmospheric nuclei (N, O) Large x for cosmic-ray nuclei (p, …, Fe) Large x for cosmic-ray nuclei (p, …, Fe) Most energetic particles (namely, at large x F ) contribute mainly to subsequent shower development. ( R. Engel) High-energy hadronic interactions and their effects on cosmic-ray physics.

18. LHC J-PARC HERA RHIC Ultra-high energy cosmic rays are related to small-x physics (LHC) and large-x physics (JLab, J-PARC). High-energy hadron facilities and high-energy cosmic rays ( R. Engel, 2005)

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

20. Results & Future experiments JLab Factory MINAR A Fermilab J-PARC RHIC LHC RHIC LHC Fermilab J-PARC GSI eLIC eRHIC eLIC eRHIC E866 E906 J-PARC J-PARC proposal J. Chiba et al. (2006) (HKN07)

21. Situation of polarized PDFs Gluon and antiquark distributions have large uncertainties at large x. J-PARC

22. Structure functions (in e scattering) Parton model Tensor structure at high energies (Note: No polarized proton beam is needed!) 1st measurement of b 1 : (HERMES) A. Airapetian et al., PRL 95 (2005) 242001. 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 「非偏極」クォーク分布

23. Elastic Scattering: A+B  C+D at large p T L.Y. Zhu et al., PRL 91 (2003) 022003 H. Gao Transition from hadron degrees of freedom to quark-gluon d.o.f. Constituent counting rule n = n A + n B + n C + c D (total number of interacting elementary particles) J-PARC: p + p  p + p

24. Color Transparency Investigate p A  p p (A-1) At large momentum transfer, a small-size component of the hadron wave function should dominate. This small-size hadron could freely pass through nuclear medium. (Transparent) Hadron size ~ 1 / hard scale Color transparency: T  larger, as the hard scale  larger (BNL-EVA) J. Aclander et al., PRC 70 (2004) 015208 “Probe of dynamics of elementary reactions” Possibility at J-PARC Incident energy (GeV) 103050 0 0.40.8 12 C (p,2p) at J-PARC T

25. Generalized Parton Distributions (GPDs) GPDs are defined as correlation of off-forward matrix. Bjorken variable Momentum transfer squared Skewdness parameter p= p +  p k q q –q –q –q –k+q k +k +k +k + t =  2  * * * * Forward limit: PDFs First moments: Form factors Dirac and Pauli form factors F 1, F 2 Axial and Pseudoscalar form factors G A, G P Second moments: Angular momenta

26. Emission of quark with momentum fraction x+  Emission of antiquark with momentum fraction  -x GPDs at J-PARC GPDs at J-PARC: SK, M. Strikman, K. Sudoh, in progress.  p p B p GPDs qq Meson distribution amplitude Quark distributionAntiquark distribution (I) (II) N  * * * *N In lepton scattering N  * * * *  (other hadron) N At J-PARC E. R. Berger, M. Diehl, B. Pire, PRL B523 (2001) 265.

27. Short-range NN interaction Short-range repulsive core, Tensor force Short-range repulsive core, Tensor force Quark degrees of freedom Quark degrees of freedom Cold dense nuclear matter, Neutron star Cold dense nuclear matter, Neutron star Ciofi degli Atti@J-PARC-NP07 E. Piasetzky et al., PRL97 (2006) 162504 Strikman@INPC07 Nuclei do not collapse  Short-range repulsive core r V(r) Nucleon size r ≈ 0.8 fm Average nucleon separation in a nucleus: R ≈ 2 fm ~ 2r  The short-range part is important as the density becomes larger (neutron star). (neutron star). 0.4 fm A(p, 2pN)X experiment for short range correlation initialfinal p n p p

28. Fragmentation functions at J-PARC J-PARC Gluon and light-quark fragmentation functions have large uncertainties. Global analysis results for  (HKNS07) Large differences between the functions of various analysis groups.

29. Criteria for determining f 0 structure by its fragmentation functions Discuss 2nd moments and functional forms (peak positions) of the fragmentation functions for f 0 by assuming the above configurations, (1), (2), (3), and (4). M. Hirai, SK, M. Oka, K. Sudoh, PRD 77 (2008) 017504.

30. Summary There are interesting topics which could be investigated by using 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 physics Charm nuclear physics Large-x part of parton distribution functions Large-x part of parton distribution functions Perturbative QCD Perturbative QCD Tensor structure at high energy Tensor structure at high energy Exotic hadron search by fragmentations Exotic hadron search by fragmentations Transition from quark to hadron degrees of freedom Transition from quark to hadron degrees of freedom Short-range nuclear force Short-range nuclear force Color transparency Color transparency Generalized parton distributions Generalized 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

31. The End