leptonic structure functions of photons
DESCRIPTION
Leptonic Structure Functions of Photons. Klaus Dehmelt Laszlo Baksay Marcus Hohlmann. Dual nature of photons: uncertainty principle allows photon to fluctuate into various states (leptons, quarks, …) Lifetime of virtual particles: Photon is ideal tool for probing structure of objects. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/1.jpg)
73rd Annual Meeting
November 9-11, 2006
Leptonic Structure Functions of Photons
Klaus DehmeltLaszlo Baksay
Marcus Hohlmann
![Page 2: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/2.jpg)
SESAPS 2006K. Dehmelt - November, 11th
The Concept of the“Structure of the Photon”
Dual nature of photons: uncertainty principle allows photon to fluctuate into various states (leptons, quarks, …)
Lifetime of virtual particles:
Photon is ideal tool for probing structure of objects
tE
m pa ir
2
2
![Page 3: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/3.jpg)
SESAPS 2006K. Dehmelt - November, 11th
Why studying leptonic structure function ?
• QED test up to
• Measurement of leptonic structure function check for experimental procedures adopted for QCD
• Background to many processes
• Calibration process for pp colliders
O ( ) 4
![Page 4: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/4.jpg)
SESAPS 2006K. Dehmelt - November, 11th
LEP-L3 Experiment at CERNLarge Electron Positron
Collider LEP
![Page 5: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/5.jpg)
SESAPS 2006K. Dehmelt - November, 11th
L3 – The Detector
![Page 6: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/6.jpg)
SESAPS 2006K. Dehmelt - November, 11th
Two-Photon Interactions withDimuon Events
Data Sample:Ec.m.s. = 189 … 206 GeV
Int. Luminosity = 600 pb-1
(*) (*)
Event Signature:• Single Tagged Electron, High Energy Deposition in Electromagnetic Calorimeters• Two tracks, at least one to be identified as a lepton ()• VERMASEREN Monte Carlo generator
![Page 7: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/7.jpg)
SESAPS 2006K. Dehmelt - November, 11th
Two-Photon Interactions withDimuon Events
Data Sample:Ec.m.s. = 189 … 206 GeV
Int. Luminosity = 600 pb-1
(*) (*)
![Page 8: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/8.jpg)
SESAPS 2006K. Dehmelt - November, 11th
L3 Tagging SubdetectorsVery Small Angle Tagger – VSATLuminosity Monitor – LUMIActive Lead Ring – ALRElectromagnetic Calorimeter Endcaps – BGO Endcaps
Tagging detectors used to identify scattered electron
VSAT: huge background due to proximity to beam pipe
![Page 9: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/9.jpg)
SESAPS 2006K. Dehmelt - November, 11th
Two-Photon Interactions withDimuon Events
![Page 10: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/10.jpg)
SESAPS 2006K. Dehmelt - November, 11th
Dilepton Formalism
iM N
PQ PQ,
: density matrix
: cross-sectionsfor different helicitystates of the photon
![Page 11: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/11.jpg)
SESAPS 2006K. Dehmelt - November, 11th
Dilepton Formalism
Extraction of with GALUGA: F QED2 ,
![Page 12: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/12.jpg)
SESAPS 2006K. Dehmelt - November, 11th
Dilepton Formalism
Extraction of with GALUGA: F QED2 ,
![Page 13: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/13.jpg)
SESAPS 2006K. Dehmelt - November, 11th
Cross-Section & Structure-FunctionVERMASEREN - GALUGA
![Page 14: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/14.jpg)
SESAPS 2006K. Dehmelt - November, 11th
Cross-Section & Structure-FunctionVERMASEREN - GALUGA
Limited x-rangedue to small Q2
![Page 15: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/15.jpg)
SESAPS 2006K. Dehmelt - November, 11th
Summary
Measurement ofdifferential cross-sectionand structure-functionin the kinematical range
Data suggest P2 > 0
![Page 16: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/16.jpg)
SESAPS 2006K. Dehmelt - November, 11th
Outlook
• Additional structure functions accessible: FA, FB
Interference terms
• Modulated by and
![Page 17: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/17.jpg)
SESAPS 2006K. Dehmelt - November, 11th
![Page 18: Leptonic Structure Functions of Photons](https://reader035.vdocument.in/reader035/viewer/2022062323/568160ec550346895dd021a7/html5/thumbnails/18.jpg)
SESAPS 2006K. Dehmelt - November, 11th