1 / 13

Laurent Schoeffel CEA/Saclay (DAPNIA/SPP)

HEP2005 Europhysics Conference in Lisboa, Portugal. Inclusive NC and CC Diffraction. Laurent Schoeffel CEA/Saclay (DAPNIA/SPP). On behalf of H1 and ZEUS collaborations. 1. Results from H1 and ZEUS experiments : Q²<120 GeV² 2. Interpretation in perturbative QCD

yahto
Download Presentation

Laurent Schoeffel CEA/Saclay (DAPNIA/SPP)

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. HEP2005 Europhysics Conference in Lisboa, Portugal Inclusive NC and CC Diffraction Laurent Schoeffel CEA/Saclay (DAPNIA/SPP) On behalf of H1 and ZEUS collaborations 1. Results from H1 and ZEUS experiments : Q²<120 GeV² 2. Interpretation in perturbative QCD 3. Large Q² Rapidity Gap Events (Q²>200 GeV²) : NC and CC

  2. Inclusive diffraction Diffractive event in the H1 detector : Kinematic variables : Y xIPfractional loss of the proton longitudinal momentum MX invariant mass of the diffractive final state  = xBj/xIPfraction of the + momentum carried by the interacting parton / Diff. Exchange Diffractive cross section : with rD ~ F2D F2D => diffractive parton densities of the Diffractive Exchange

  3. New measurement by ZEUS With the Forward Plug Calorimeter MY>2.3 GeV => EFPC>1 GeV recognised and rejected Mx selection method : d*pdiff /dlnMX² ~ constant for a diffractive event

  4. New measurement by ZEUS With the Forward Plug Calorimeter d*pdiff /dMX² ~ 1/MX² for a diffractive event… Mx=1120 GeV We observe : d*pdiff /dMX ~ Wa rising with W (a>0) From Regge theory : a=4(IP(t)-1) For soft IP (IP~1.08) => a ~ 0.2/0.3 (Mx<2 GeV) Note : d*pdiff /dMx²~4²/[Q²(Q²+Mx²)] xIPF2D

  5. Perturbative QCD and hard diffraction ddiff /dMX ~ Wa with a = 2.(2IP-2) MX < 2 GeV => soft pomeron MX > 2 GeV => transition from soft to hard process(Q²) => large Q² + large MX : perturbative regime Mx > 2 GeV Q² > 15 GeV²

  6. Scaling violations Large scaling violations even at large  => large Gluon Low xIP ~xIP F2D(3) Note : H1 measures in the range MY<1.6 GeV 97 data with 10 pb-1 for Q²>13.5 GeV²

  7. Combination of both data sets H1/ZEUS => Compatible After scaling the measurements in the same MY range Plot from the HERA/LHC workshop

  8. J. Bartels at al., Eur. Phys. J. C7, 443 (1999). Phenomenology of the 2-gluon exchange model LO realisation of the Singlet Exchange L or T =Q²/(Q²+Mx²) ~1/Q² at large  => HigherTwist behaviour

  9. Fraction of Diffraction vs the total cross-section Behaviour well explained in the dipolesaturation model Mx>8 GeV bins : => Diffraction is dominated by qq and qqg For example at very low , one gluon carries the momentum xBjp+ => We expect the same W dep. // F2

  10. Rapidity Gap Event at Large Q² NC/CC Example of event in the H1 detector X Rapidity Gap Missing transverse energy

  11. Results on CCDiff H1 : CCDiff/CCIncl = 2.50.80.6% NC ratio decreases with Q² : It was ~15/20% at medium Q² and it reaches ~2/3% for Q²>200 GeV² CC and NC fractions are compatible

  12. Conclusions New results from ZEUS with a Forward Plug Calorimeter to measure the forward activity : Ratio Diff/Incl ~ 15/20% at medium Q² Well described by the 2-gluon exchange in the perturbative domain A large gluon content of diffractive exchange is found by H1 by scaling violations (QCD fit) Rapidity Gap Events at large Q² : interesting as it gives access to CC events Fractions NCDiff/NCIncl and CCDiff/CCIncl are compatible and decreasing with Q² : CCDiff/CCIncl ~ 3% in the range of measurement (Q²>200 GeV²) : H1 and ZEUS give compatible results

More Related