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Hard diffraction in eA

Hard diffraction in eA. Cyrille Marquet RIKEN BNL Research Center. Inclusive and diffractive structure functions. e h center-of-mass energy S = ( k + P ) 2  * h center-of-mass energy W 2 = ( k - k ’+ P ) 2 photon virtuality Q 2 = - ( k - k ’) 2 > 0. k’. k. size resolution 1/Q. p.

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Hard diffraction in eA

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  1. Hard diffraction in eA Cyrille MarquetRIKEN BNL Research Center

  2. Inclusive and diffractivestructure functions

  3. eh center-of-mass energyS = (k+P)2*h center-of-mass energyW2 = (k-k’+P)2photon virtualityQ2 = - (k-k’)2 > 0 k’ k size resolution 1/Q p Deep inelastic scattering (DIS) x ~ momentum fraction of the struck parton y~ W²/S

  4. momentum transfert = (P-P’)2 < 0diffractive mass of the final stateMX2 = (P-P’+k-k’)2 k’ k p p’ Diffractive DIS when the hadron remains intact ~ momentum fraction of the struck parton with respect to the Pomeron xpom = x/ rapidity gap :  = ln(1/xpom) xpom~ momentum fraction of the Pomeron with respect to the hadron

  5. Diffractive DIS without proton tagging e p  e X Y with MY cut H1 LRG data MY < 1.6 GeV ZEUS FPC data MY < 2.3 GeV Inclusive diffraction at HERA Diffractive DIS with proton tagging e p  e X p H1 FPS data ZEUS LPS data

  6. Collinear factorizationvsdipole factorization

  7. perturbative Collinear factorization in the limit Q²   withx fixed • for inclusive DIS a = quarks, gluons • perturbative evolutionof  with Q2 : Dokshitzer-Gribov-Lipatov-Altarelli-Parisi not valid if x is too small non perturbative • for diffractive DIS another set of pdf’s, same Q² evolution

  8. Factorization with diffractive jets ? you cannot do much with the diffractive pdfs factorization does not hold for diffractive jet production at low Q² diffractive jet production in pp collisions factorization also holds for diffractive jet production at high Q² for instance at the Tevatron: predictions obtained with diffractive pdfs overestimate CDF data by a factor of about 10 a very popular approach: use collinear factorization anyway, and apply a correction factor called the rapidity gap survival probability

  9. k’ k’ k k photon virtuality Q2 = - (k-k’)2 >> QCD *p collision energy W2 = (k-k’+p)2 2 size resolution 1/Q p p p’ • diffractive DIS: diffractive mass MX2 = (k-k’+p-p’)2 xpom = x/ rapidity gap = ln(1/xpom) The QCD dipole picture in DIS in the limit x  0withQ²fixed • deep inelastic scattering (DIS) at small xBj : sensitive to values of x as small as

  10. T = 1 T << 1 contribution of the different r regions in the hard regime DIS dominated by relatively hard sizes DDIS dominated by semi-hard sizes hard diffraction is directly sensitive to the saturation region Forshaw and Shaw no good fit without saturation effects Hard diffraction and small-x physics the dipole scattering amplitudfe dipole size r

  11. Hard diffraction off nucleisome expectations

  12. following the approach of Kugeratski, Goncalves and Navarra (2006) ratio ~ 35 % from Kowalski-Teaney model plots from Tuomas Lappi The ratio F2D,A / F2 A at HERA saturation naturally explains the constant ratio

  13. scheme dependence for naive : Pb / p FRWS : Freund, Rummukainen, Weigert and Schafer ASW : Armesto, Salgado and Wiedemann The ratio F2D,A / F2 D,p following Kugeratski, Goncalves and Navarra Au / d • x dependence full : Iancu-Itakura-Munier model linear : linearized version of IIM shape and normalization influenced by saturation

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