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Chung-Wen Kao Chung-Yuan Christian University Taiwan

Chung-Wen Kao Chung-Yuan Christian University Taiwan. Review of TBE Physics: Odyssey in the Box. 15 th Taiwan Nuclear Physics Summer School Iop AS, 06/27/2011. Odysseus and the Sirens, Greek Red-Figure Stamnos Vase, c. 480-460 BCE, British Museum. or get me out of the box!.

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Chung-Wen Kao Chung-Yuan Christian University Taiwan

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  1. Chung-Wen Kao Chung-Yuan Christian University Taiwan Review of TBE Physics: Odyssey in the Box 15th Taiwan Nuclear Physics Summer School Iop AS, 06/27/2011 Odysseus and the Sirens, Greek Red-Figure Stamnos Vase, c. 480-460 BCE, British Museum

  2. or get me out of the box!

  3. Collaboration and Reference In Collaboration with Hai-Qing Zhou (SouthEast U, China), Keitaro Nagata(CYCU, Taiwan), Yu-Chun Chen(AS, Taiwan), M. Vanderhaeghen(Mainz, Germany), Shin-Nan Yang (NTU,Taiwan) This talk is based onthe following works: (1) H-Q Zhou, CWK, S-N. Yang: Phys.Rev.Lett.99:262001,2007 (2) K.Nagata, H-Q Zhou, CWK, S-NYang: Phys.Rev.C79:062501,2009. (3) H-Q Zhou, CWK,S-N Yang, K. Nagata: Phys.Rev.C81:035208,2010 (4) Y.C. Chen, CWK, M. Vanderhaeghen: arXiv: 0903.1098

  4. Prologue: All about the proton

  5. Proton: our playground • Nucleon is the basic building block of atomic nuclei. • Its internal structure, arising from the underlying quark and gluon constituents, determines its mass, spin, and interactions. • These, in turn, determine the fundamental properties of the nuclei. • Furthermore, proton, as the only stable hadron, provides us the unique opportunity to explore its static properties up to very high precision.

  6. electron virtuality ( ) * g Q Using photon as probe • Since the quark carries the electric charge and photon does not participate the strong interaction, the photon is a very good probe. • Experiments with highly energetic electromagnetic probe acting as a micro-scope

  7. 2 PD hadronization One-Photon Physics: From Low to High High Q2, deeply inelastic, inclusive Low Q2, elastic, exclusive Parton distribution Form factors, resonance

  8. "What walks on four feet in the morning, two in the afternoon and three at night?". Oedipus answered: "Man”. "What looks like a single particle in low Q2, a bond state of heavy constituents in the middle and a bag of sands at high Q2?". Oedipus: &^%&$$%??? To completely understand the properties of the proton from QCD is our Holy Grail ….. Oedipus explains the riddle of the Sphinx,

  9. Devil is near…. • With the recent development of the polarization technology, many experiments can reach record-breaking precision. • However when experimentalists march, a devil is approaching in silence… • We think we know many things about the proton precisely, but do we? Not really, HiHiHi…..

  10. ACT 1: In the beginning…. Form factors and TPE effects

  11. Form factor in quantum mechanics The cross section: Atomic form factor: charge density is the Fourier transform of the charge density. E.g., the hydrogen atom in the ground state: with Bohrradius

  12. Nucleon E.M form factors "for his pioneering studies of electron scattering in atomic nuclei and for his thereby achieved discoveries concerning the structure of the nucleons.(1961) • Hofstadterdetermined the precise size of the proton by measuring their form factor in late 1950s.

  13. Rosenbluth Separation Method Within one-photon-exchange framework:

  14. Polarization Transfer Method Polarization transfer cannot determine the values of GE and GM but can determine their ratio R.

  15. Inconsistency between two methods SLAC, JLab Rosenbluth data JLab/HallA Polarization data Jones et al. (2000) Gayou et al (2002)

  16. J.Arrington, P.G.Blunden, W.Melnitchuk, arXiv1105.0951

  17. Go beyond One-Photon exchange P. A. M. Guichon and M. Vanderhaeghen, Phys. Rev. Lett. 91, 142303 (2003). New Structure

  18. P. A. M. Guichon and M. Vanderhaeghen, Phys. Rev. Lett. 91, 142303 (2003). Two-Photon-Exchange Effects on two techniques small large

  19. One way or another……. • There are two ways to estimate the TPE effect: Use models to calculate Two-Photon-Exchange diagrams: Like parton model, hadronic model and so on….. Direct analyze the cross section and polarization data by including the TPE effects: One-Photon-exchange Two-photon-exchange

  20. Why Box diagram is not trivial ? One needs evaluate the Compton tensor. In general, it owns 18 structures! Furthermore, There is no single framework to computer this quantity with arbitrary k2 and (q-k)2.

  21. Results of hadronic model Insert the on-shell form factors P.G.Blunden, W.Melnitchouk and J.A.Tjon, Phys.Rev.Lett. 91 (2003) 142304

  22. Inclusion of resonances Insert the on-shell form factors S.Kondratyuk, P.G.Blunden, W.Melnitchouk and J.A.Tjon, Phys.Rev.Lett. 95 (2005) 172503

  23. Partonic Model Calculation GPDs A. V. Afanasev, S. J. Brodsky, C. E. Carlson, Y.-C. Chen, and M. Vanderhaeghen, Phys. Rev. D 72, 013008 (2005).

  24. DVCSDeeply Virtual Compton Scattering DVMPDeeply Virtual Meson Production DA Hard gluon GPDs GPDs GPDs can be accessed via exclusive reactionsin the Bjorken kinematic regime. Longitudinal response only • The DVCS process is identified via double (eg) or triple (egN) coincidences, allowing for small scale detectors and large luminosities. Factorisation applies only to longitudinally polarized virtual photons whose contribution to the electroproduction cross section must be isolated. . 5/6

  25. QCD factorization approach The leading perturbative QCD (pQCD) contribution to the 2 γ exchange correction to the elastic ep amplitude is given by a convolution integral of the proton distribution amplitudes (DAs) with the hard coefficient function N.Kivel and M.Vanderhaeghen, Phys. Rev. Lett.103 (2009) 092004 1γ 1γ+2 γ(BLW) 1γ+2 γ(COZ)

  26. Comparison with data arXiv:1012.0339 JLab Hall C

  27. Model-independent analysis Determined from polarization transfer data TPE effects Inputs From crossing symmetry and charge conjugation:

  28. Our Choice of F(Q2, ε) ε→ 1, y→0, F→0 ε→0, y→1, F≠0 Fit (A) Fit (B)

  29. Result of fits Dashed Line: Rosenbluth Solid line: Fit (A) Dotted line: Fit (B)

  30. Result of fits Dashed Line: Rosenbluth Solid line: Fit (A) Dotted line: Fit (B)

  31. Puzzle about nonlinearity V.Tvaskis et al, PRC 73, 2005 Purely due to TPE

  32. TPE vs OPE Fit (A) : Fit (B):

  33. TPE contribution to slope Dashed Line : Fit (B) Solid line: Fit (A) SLOPE(TPE)/SLOPE(OPE) =C1/(GE/τ)

  34. Fit (A) Fit (B)

  35. Empirical extraction of TPE

  36. Upcoming TPE experiments Olympus@DESY experiment are underway. Over the measured range of this experiment, the 2TPE corrections to the e+p/e−p elastic cross section ratio are predicted to vary in the 1 - 6 % range. J.Guttmann, N. Kivel, M. Meziane,and M. Vanderhaeghen, arXiv1012.0564

  37. Jlab Hall B E-07-005

  38. More TPE….. • TPE and pion form factors: Y.-B.Dong, S.D.Wang, Phys.Lett. B684, 123-126 (2010). P.G.Blunden, W.Melnitchouk, J.A.Tjon, Phys. Rev. C81, 018202 (2010). • TPE and deuteron form factors: Y.B.Dong, D.Y.Chen,'Phys. Lett. B675, 426-432 (2009). A.P.Kobushkin, Y.D.Krivenko-Emetov, S.Dubnicka, Phys. Rev. C81, 054001 (2010). A.P.Kobushkin, Y.D.Krivenko-Emetov, [arXiv:1101.1867 [nucl-th]]. Y.~B.~Dong, Phys. Rev. C82, 068202 (2010). • TPE and time-like proton form factors: H.Q.Zhou, D.Y.Chen, Y.B.Dong, Phys.Lett. B675, 305-307 (2009). J.Guttmann, N.Kivel, M.Vanderhaeghen, [arXiv:1101.5967 [hep-ph]].

  39. Act 2: How strange is strange?TPE effect in parity-violating ep elastic scattering

  40. Strangeness in the nucleon « sea » • s quark: cleanest candidate to study the sea quarks Goal:Determine the contributions of the strange quark sea ( ) to the charge and current/spin distributions in the nucleon : “strange form factors” GsE and GsM

  41. Parity Violating ep Elastic Scattering Interference:  ~ |MEM |2 + |MNC |2 + 2Re(MEM*)MNC Interference with EM amplitude makes Neutral Current (NC) amplitude accessible Tiny (~10-6) cross section asymmetry isolates weak interaction

  42. OPE vs OZE

  43. Isolating the neutral weak form factors: vary the kinematics or the targets Forward angle Backward angle For a proton: ~ few parts per million

  44. Flavour decomposition NC probes same hadronic flavour structure, with different couplings: • GZE/M provide an important new benchmark for testing • non-perturbative QCD structure of the nucleon

  45. Gg,pE,M GuE,M GpE,M Well Measured Charge symmetry Gg,nE,M GdE,M Shuffle GnE,M GsE,M GZ,pE,M GsE,M <N| sγμs |N> Apply Charge Symmetry

  46. Tree Level is not enough! • The strange form factors are found to be very small, just few percents. • To make sure the extracted values are accurate, it is necessary to take the radiative correction into consideration! • So one has to draw many diagrams as follows…..

  47. Electroweak radiative corrections Squeeze eq→eq amplitudes into 4-Fermion contact interactions

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