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High-Energy Hadron Physics at J-PARC

High-Energy Hadron Physics at J-PARC. shunzo.kumano@kek.jp http://research.kek.jp/people/kumanos/. Shunzo Kumano High Energy Accelerator Research Organization (KEK) Graduate University for Advanced Studies (GUAS). 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.

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High-Energy Hadron Physics at J-PARC

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  1. High-Energy Hadron Physicsat J-PARC shunzo.kumano@kek.jp http://research.kek.jp/people/kumanos/ Shunzo Kumano High Energy Accelerator Research Organization (KEK) Graduate University for Advanced Studies (GUAS) 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 September 1 – 2, 2008 (Talk on Sept. 2)

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

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

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

  5. Motivations and Issues

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

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

  9. Flavor asymmetric antiquark distributions: u / d この領域での物理的意義を理論的に検討しておく E866 J-PARC E906 http://www.acuonline.edu/academics /cas/physics/research/e906.html J-PARC proposal (P24), M. Bai et al. (2007) This project is suitable for probing “peripheral structure” of the nucleon.

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

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

  13. Comments on Structure Functions III 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)  …

  14. Comments on Structure Functions IV 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?)

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

  16. CTEQ5M1 MRS2001 CTEQ5HJ PDF uncertainty u d CTEQ6 (J. Pumplin et al.), JHEP 0207 (2002) 012 Important x region for finding an “exotic event” in a high-pT region at LHC g 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. p, …, Fe N, O High-energy cosmic ray interactions High-energy hadronic interactions and their effects on cosmic-ray physics. Most energetic particles (namely, at large xF ) contribute mainly to subsequent shower development. • Small x for atmospheric nuclei (N, O) • Large x for cosmic-ray nuclei (p, …, Fe) ( R. Engel)

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

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

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

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

  22. Tensor structure at high energies (Note: No polarized proton beam is needed!) Structure functions (in e scattering) 1st measurement of b1: (HERMES) A. Airapetian et al., PRL 95 (2005) 242001. Parton model 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 pT Transition from hadron degrees of freedom to quark-gluon d.o.f. H. Gao Constituent counting rule n = nA + nB + nC + cD (total number of interacting elementary particles) J-PARC: p + p  p + p L.Y. Zhu et al., PRL 91 (2003) 022003

  24. 0.8 12C 0.4 (p,2p) at J-PARC 0 10 30 50 Incident energy (GeV) Color Transparency “Probe of dynamics of elementary reactions” 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) Possibility at J-PARC Investigate pApp(A-1) T Hadron size ~ 1 / hard scale Color transparency: T  larger, as the hard scale  larger (BNL-EVA) J. Aclander et al., PRC 70 (2004) 015208

  25.  *  q– q k+q k+ k p p= p+ t=2 Generalized Parton Distributions (GPDs) GPDs are defined as correlation of off-forward matrix. Bjorken variable Momentum transfer squared Skewdness parameter Forward limit: PDFs First moments: Form factors Dirac and Pauli form factors F1 , F2 Axial and Pseudoscalar form factors GA , GP Second moments: Angular momenta

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

  27. initial final Short-range NN interaction • Short-range repulsive core, Tensor force • Quark degrees of freedom • Cold dense nuclear matter, Neutron star Ciofi degli Atti@J-PARC-NP07 Strikman@INPC07 E. Piasetzky et al., PRL97 (2006) 162504 V(r) 0.4 fm Nuclei do not collapse  Short-range repulsive core 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). A(p, 2pN)X experiment for short range correlation p n p p

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

  29. M. Hirai, SK, M. Oka, K. Sudoh, PRD 77 (2008) 017504. Criteria for determining f0 structure by its fragmentation functions Discuss 2nd moments and functional forms (peak positions)of the fragmentation functions for f0 by assumingthe above configurations, (1), (2), (3), and (4).

  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, … (talks by Goto and Tanaka) • Charm nuclear physics • Large-x part of parton distribution functions • Perturbative QCD • Tensor structure at high energy • Exotic hadron search by fragmentations • Transition from quark to hadron degrees of freedom • Short-range nuclear force • Color transparency • Generalized parton distributions Need • theoretical ideas and experimental feasibility studies • attractive slogan(s) and PR to the public

  31. The End The End

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