1 / 16

Kazutaka Sudoh (KEK) INPC2007, Tokyo June 5, 2007

Global Analysis of Hadron-production Data in e + e - Annihilation for Determining Fragmentation Functions. Kazutaka Sudoh (KEK) INPC2007, Tokyo June 5, 2007. In collaboration with M. Hirai (TITech), S. Kumano (KEK), and T.-H. Nagai (The Grad. Univ.).

abel
Download Presentation

Kazutaka Sudoh (KEK) INPC2007, Tokyo June 5, 2007

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Global Analysis of Hadron-production Data in e+e- Annihilation for Determining Fragmentation Functions Kazutaka Sudoh (KEK) INPC2007, Tokyo June 5, 2007 In collaboration with M. Hirai (TITech), S. Kumano (KEK), and T.-H. Nagai (The Grad. Univ.) Reference: Phys. Rev. D 75, 094009 (2007) http://research.kek.jp/people/kumanos/ffs.html • Introduction • Global Analysis of Fragmentation Functions • Uncertainty Estimation • Summary

  2. h : scaling variable q : CMS energy Coefficient Function calculable in pQCD Fragmentation Function extracted from experiments q Fragmentation Function in • Fragmentation Functions (FFs): • Fragmentation process occurs from quarks, anti-quarks, and gluons, so that Fh is expressed in terms of their contributions: energy fraction of hadron and primary quark

  3. : j→i splitting function Favored FFs: Disfavored FFs: • Momentum (Energy) Sum Rule • Energy conservation should be hold for each flavor • DGLAP equation: controls the energy dependence of FFs • Favored and Disfavored Fragmentation Functions from a quark which exists in a naïve quark model from a quark which does not exist in a naïve quark model

  4. Present Status of FFs • There are two widely used FFs by Kretzer and KKP. • An updated version of KKP is AKK. KretzerS. Kretzer PRD62, 054001 (2000) KKPB.A. Kniehl, G. Kramer, B. Potter, NPB582, 514 (2000) AKKS. Albino, B.A. Kniehl, G. Kramer, NPB725, 181 (2005) But, these functions are very different. Large differences indicate that the current FFs have much ambiguities. In this work • Independent global analysis of FFs including new data • Estimate their uncertainties (It’s new!!!) Just after our analysis, a new parametrization including ep and pp reactions is proposedby D. de Florian, R. Sassot, M. Stratmann (hep-ph/0703242)

  5. Purpose for investigating FFs Fragmentation Functions (FFs) are key issue in high energy hadron production processes. • Origin of proton spin • Properties of quark-gluon matter Quark, anti-quark, gluon contribution to proton spin (gluon polarization, flavor separation) Nuclear modification (recombination, energy loss,,,)

  6. Determination of FFs • Determination of fragmentation functions and their uncertainties in LO and NLO • Discuss NLO improvement in comparison with LO • Role of higher order corrections in the determination • Comparison with other parametrizations • SLD 2004 data (accurate) are included. New aspects in our analysis

  7. Ansatz (for p±) • Function form (simplest form) • Constraint condition • 2nd moment should be finite and less than 1

  8. Experimental Data: • the number of Data： 264 Kinematical coverage

  9. c2 Analysis • Input parameters and results • Uncertainty estimation: Hessian method • N=14, Dc2=15.94: [K(N.s): c2 distribution] MRST: EPJC23, 73; PLB531, 216 (2002)

  10. Comparison with pion Data Our fit is successful to reproduce the pion data. The DELPHI data deviate from our fit at large z. Our NLO fit with uncertainties Rational deference between data and theory (Data-Theory)/Theory

  11. Comparison with pion Data (2) • (Data-Theory)/Theory

  12. FFs with Uncertainties for pion • Gluon and light quark FFs have large uncertainties. • Uncertainties bands become smaller in NLO compared with LO. (The data are sensitive to NLO effects.) • The NLO improvement is clear especially in gluon and disfavored FFs. • Heavy quark functions are relatively well determined.

  13. Determined Functions for kaon • Gluon and light quark FFs have large uncertainties. • Uncertainties bands become smaller in NLO compared with LO. • Heavy quark functions are relatively well determined. Two favored functions for kaon The situation is similar to the pion funcions

  14. Comparison with Other Parametrizations for pion HKNS(Hirai, Kumano, Nagai, Sudoh) Kretzer KKP(Kniehl, Kramer, Potter) AKK(Albino, Kniehl, Kramer) DSS(deFlorian, Sassot, Stratmann) • evolved to Q2=2, 10, 100 GeV2 • All functions are different, but consistent within uncertainties bands.

  15. ---- DSS Comparison for kaon and proton kaon proton

  16. Summary • Global analysis of FFs was done for independent parametrization • Determine function forms forp, K, pin LO, NLO analyses • Uncertainties of FFs were estimated • Large uncertainties in gluon and disfavored functions • Heavy quark functions are well determined. • Uncertainties could be reduced by performing NLO analysis • Importance of accurate FFs • The uncertainties at low Q2 are very important for discussing Nucleon’s spin and/or heavy ion physics. (e.g. hadron production at smallpTat RHIC) • Need for accurate “low-energy” data by Belle & BaBar • Program code for calculating our FFs is now available at http://research.kek.jp/people/kumanos/ffs.html

More Related