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Simonetta Liuti for Alessandra Fantoni (INFN Frascati)

Simonetta Liuti for Alessandra Fantoni (INFN Frascati). SPIN 2008 University of Virginia. Outline. Introduction Status of Experimental Data at large Bjorken x Approaches to Parton-Hadron Duality Extraction of Higher Twists

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Simonetta Liuti for Alessandra Fantoni (INFN Frascati)

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  1. Simonetta Liuti for Alessandra Fantoni (INFN Frascati) SPIN 2008 University of Virginia

  2. Outline Introduction Status of Experimental Data at large Bjorken x Approaches to Parton-Hadron Duality Extraction of Higher Twists Conclusions/Outlook:which experiments, observables, targets for Jlab at 12 GeV?

  3. 1. Introduction

  4. What is parton-hadron duality? Observation of similarity between “high” and “low” energy cross sections Resonances follow “smooth” parton model curve Theoretical background: Finite Energy Sum Rules (FESR) Dolen, Horn and Schmid, PR166(1968) Is there an interpretation within QCD? Shifman (2005), Bigi and Uraltsev (2004)

  5. Why is it important to study parton hadron duality? • To monitor the transition between the “perturbative QCD” region, where factorization applies to the “non-perturbative QCD region (alpha strong? Talk by A. Deur) • To understand mechanisms of hadron formation • Practical reason (Jlab studies): to properly extend the domain of validity of PDF global analyses (example of large x gluons)

  6. Experimental observations of duality encompass several processes

  7. What does a quantitative analysis of duality entail? • Study of ranges of validity in x and Q2 • Are there differences between polarized and unpolarized data? • Isospin dependence n vs. p? • Global duality (over all resonances) vs. Local duality (resonance by resonance) • In order to carry out this program we performed a systematic analysis of world data • Interesting outcome!

  8. Program started with N. Bianchi, A. Fantoni and S.L., PRD What remains is “Higher Twist”, not predicted within the “standard” perturbative series

  9. Target Mass Corrections (TMC) Georgi, Politzer, ‘70s

  10. Recent development!Accardi, Qiu, JHEP (2008) It is possible to extend range of validity without introducing mismatches between the x and range Instead of 1

  11. Large x resummation(D. Amati et al. (1980), S. Brodsky (1980), R. Roberts, Z. Phys. (1999) …) This modifies Wilson Coefficient: Divergent ln(1-z) are effectively “resummed” Approach valid at NLO!

  12. But needs to be continued at very low Q2 A. Deur’s talk

  13. Results Bianchi, Fantoni, Liuti (2003)

  14. …up to 2006

  15. additive form

  16. Conclusions and Outlook • Parton-hadron duality is interesting theoretically: low to high energy connection… • Quantitative studies of parton-hadron duality are important in “Global Analyses” but… all aspects including TMCs, LxR, and dynamical HTs need to be included\ • Interesting to compare unpolarized and polarized results

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