1 / 37

Higher Twist in PVDIS Workshop Conclusions

Higher Twist in PVDIS Workshop Conclusions. Conclusion. Complications due to higher twist can be handled with the proposed data set, so the proposed SM test is valid. We will obtain unique data on 4-quark higher twist operators. This physics should be a bullet in the abstract ov the proposal.

ernie
Download Presentation

Higher Twist in PVDIS Workshop Conclusions

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. Higher Twist in PVDIS Workshop Conclusions Higher twist summary

  2. Conclusion • Complications due to higher twist can be handled with the proposed data set, so the proposed SM test is valid. • We will obtain unique data on 4-quark higher twist operators. This physics should be a bullet in the abstract ov the proposal. Higher twist summary

  3. Deep Inelastic Scattering e- e- * Z* X N a(x) and b(x) contain quark distribution functions fi(x) For an isoscalar target like 2H, structure functions largely cancel in the ratio at high x at high x Hadronic physics in a(x) must be controlled to high precision. We can be sloppier with b(x), since it is small. 0 1 Suppressed by a factor of 7 C2q inaccessible in elastic scattering Higher twist summary

  4. Phenomenology There are 5 relevant structure functions Higher twist summary

  5. Physics of the Dominant Vector- Hadronic Piece: a(x) Bjorken, PRD 18, 3239 (78) Wolfenstein, NPB146, 477 (78) Zero in QPM Pure 4-quark HT operator No Quark-gluon HT Higher twist summary

  6. 4-Quark operators • APV presents a unique laboratory where 4-quark operators can be isolated form quark-gluon operators. • If they are large enough for us to observe, they will be very interesting. • 4-quark matrix elements are easy to compute on the lattice (No disconnected graphs). Higher twist summary

  7. Quark-Quark and Quark-Gluon What is a true quark-gluon operator? Parton Model or leading twist Quark-gluon diagram d u Same Flavor Di-quarks Higher twist summary

  8. NLO Diagrams DGLAP Evolution Diagrams (a)-(c) cancel in APV Higher twist summary

  9. Relate HT to Nucleon • Need anomalous dimensions to evolve HT observations at Q2~10 to low Q2 of models, etc. • These calculations should be done is a year ( or so). Higher twist summary

  10. Heavy Quark Physics Community • HT is not viewed as important to problems in B meson decays. • HT is called power corrections by this community. Higher twist summary

  11. R for γ vs Z in Neutrino Scattering From Kulagin and Petti, PRD 76, 094023 (07) Higher twist summary

  12. New Insight • In neutrino scattering, there is an axial-axial piece which is nontrivial. • For FLγZ, everything is vector. It is much simpler. Higher twist summary

  13. Approximations • QPM: Cross sections given by PDF’s • DGLAP QPM: Evolve PDF’s • Higher Twist Higher twist summary

  14. The RγZ Problem • FL is zero in the QPM but nonzero in DGLAP QPM. • Source of FL is: • Gluons • Gluon radiation form quarks • Both are isoscalar for deuterium, so FL cancels in APV for dueterium. • Corrections for H can be computed in DGLAP. Higher twist summary

  15. Higher Twist Coefficients in parity conserving (Di) and nonconserving (Ci) Scattering Evolves according To DGLAP equations Higher Twist is what is left over Higher Twist is any Q2-dependent deviation From the SM prediction (Does not Evolve) Higher twist summary

  16. Going from LO to NNNLO Greatly Reduces Higher Twist Coefficients F2(x,Q2)=F2(x)(1+D(x)/Q2) Q2=(W2-M2)/(1/x-1) Q2min=Q2(W=2) MRST, PLB582, 222 (04) APV=APV(1+C(x)/Q2) If D(x)~C(x), Parity might show higher twist At high x without needing QCD evolution. Higher twist summary

  17. F2D(x): All x on Same Scale Are moments dominated by large x? Caution: target mass not subtracted Plot by Mindy Higher twist summary

  18. D(x) versus x Fractional HT APV at large x is very sensitive to HT Probably quark-gluon (but it could be quark-quark) Higher twist summary Plot by Mindy

  19. x-dependence of Higher Twist • Relative 4-quark higher twist should increase with x??? Higher twist summary

  20. Target Mass Corrections • Talk by Tim. • Various methods. (Subject is complex) • Lots of cancellation. • Errors negligible if corrections are done consistently with other corrections. Higher twist summary

  21. Higher twist summary

  22. Higher twist summary

  23. Higher twist summary

  24. New Strategy for b(x) HT • Use data for F2γ • F3ν HT data provides some information on F3γZ HT Higher twist summary

  25. Higher twist summary

  26. Measured Higher Twist in F3 and FLγ Higher twist summary

  27. Higher twist summary

  28. Statistical Errors (%) vs Kinematics Strategy: sub-1% precision over broad kinematic range for sensitive Standard Model test and detailed study of hadronic structure contributions Error bar σA/A (%) shown at center of bins in Q2, x 4 months at 11 GeV 2 months at 6.6 GeV Higher twist summary PAC34

  29. Coherent Program of PVDIS Study Strategy: requires precise kinematics and broad range Fit data to: C(x)=βHT/(1-x)3 • Measure AD in NARROW bins of x, Q2 with 0.5% precision • Cover broad Q2 range for x in [0.3,0.6] to constrain HT • Search for CSV with x dependence of AD at high x • Use x>0.4, high Q2, and to measure a combination of the Ciq’s Higher twist summary

  30. Sensitivity with PVDIS Thanks to K. Paschke Higher twist summary

  31. Sensitivity: C1 and C2 Plots 6 GeV World’s data PVDIS Precision Data PVDIS Qweak Cs Higher twist summary

  32. Fits Plot by Mindy Higher twist summary

  33. Other Strategies • Above analysis assumes SM, HT, and CVS physics are all in play. • Each of these effects may be small. • As an approximation, we can do three additional analyses in which either SM, CSV, or HT effects are neglected. Higher twist summary

  34. APV in DIS on 1H + small corrections • Allows d/u measurement on a single proton! • Vector quark current! (electron is axial-vector) • Determine that higher twist is under control • Determine standard model agreement at low x • Obtain high precision at high x Higher twist summary

  35. PVDIS on the Proton: d/u at High x Deuteron analysis has large nuclear corrections (Yellow) APV for the proton has no such corrections (complementary to BONUS) 3-month run The challenge is to get statistical and systematic errors ~ 2% Higher twist summary

  36. Higher Twist without the QPM Bjorken, PRD 18, 3239 (78) Wolfenstein, NPB146, 477 (78) Zero in QPM Higher-Twist quark-quark correlations Higher twist summary

  37. Electron-Quark Phenomenology A V V A C2u and C2d are small and poorly known: one combination can be accessed in PV DIS New physics such as compositeness, leptoquarks: Deviations to C2u and C2d might be fractionally large C2’s are a factor of 7 smaller than the C1’s Higher twist summary

More Related