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8/20/2014

11 th INTERNATIONAL CONFERENCE ON NUCLEUS-NUCLEUS COLLISIONS San Antonio, Texas, May 27 thru June 1, 2012. Hadrons in a Cold Nuclear Medium. Tulio Rodrigues, University of São Paulo, Brazil. 8/20/2014. Tulio Rodrigues – NN2012 – San Antonio – USA. 1.

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8/20/2014

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  1. 11th INTERNATIONAL CONFERENCE ON NUCLEUS-NUCLEUS COLLISIONS San Antonio, Texas, May 27 thru June 1, 2012 Hadrons in a Cold Nuclear Medium Tulio Rodrigues, University of São Paulo, Brazil 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 1

  2. 11th INTERNATIONAL CONFERENCE ON NUCLEUS-NUCLEUS COLLISIONS San Antonio, Texas, May 27 thru June 1, 2012 • The nucleus as a QCD laboratory • Chiral anomaly of QCD (2g decay of pseudoscalar mesons) • Chiral symmetry restoration in nuclei • Forward angle meson photoproduction in nuclei (MCMC model) • Confronting theory and experiment • pseudoscalar mesons (Cornell and PrimEx @ JLab) • vector mesons (TAPS and g7a @ JLab) • Conclusions and future prospects O U T L I N E 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 2

  3. The nucleus as a QCD laboratory • Chiral anomaly of QCD (theoretical scenario for p0 --> gg decay) MOTIVATION Gh --> gg used as input to obtain Gp0 --> gg beyond the LO chiral anomaly 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 3

  4. g P p0, h g* A A g P p0, h g P  p0, h r, w r, w A A A* A • Chiral anomaly of QCD: GP --> gg via the Primakoff method MOTIVATION Coulomb (Primakoff) Nuclear Coherent Nuclear Incoherent 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 4

  5. Chiral anomaly of QCD: p0 --> gg decay revisited MOTIVATION Figure: R. Miskimen, Annu. Rev. Nucl. Part. Sci. 61, 1 (2011) PrimEx data: I. Larin et al., Phys. Rev. Lett. 106, 162303 (2011) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 5

  6. Chiral anomaly of QCD: h--> gg decay revisited 20 year old puzzle! MOTIVATION Removed from the PDG world average PDG: K. Nakamura et al. (Particle Data Group), J. Phys. G 37, 075021 (2010) Cornell: A. Browman et al., Phys. Rev. Lett. 32, 1067 (1974) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 6

  7. Chiral symmetry restoration in nuclei MOTIVATION cs partially restored (1) Hatsuda et al., PRL 55, 158 (1985) Weise et al., NPA 553, 59 (1993) NPB 321, 387 (1989) PRC 45, 1881 (1992) PLB 357, 199 (1995) Hadron properties (mass, width, etc…) are supposed to change in hot and/or dense nuclear matter (1) Chaden Djalali, Modification of hadrons in the medium, talk in the VIII LASNPAP, December 15 - 19, 2009, Santiago de Chile. 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 7

  8. Chiral symmetry restoration in nuclei Light vector meson properties IN VACUUM MOTIVATION Few experiments with nucleus close to equilibrium 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 8

  9. Transparency ratios • Chiral symmetry restoration in nuclei In-medium width of vector mesons via nuclear transparency measurements MOTIVATION Nuclear transparency Cross section scaling (Incoherent) Low density theorem 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 9

  10. Concept of the time-dependent multicollisional MCMC cascade N (p2) THE MODEL k N (p1) g p2 g (k) qP P (q) q kF t < 0, Lab Frame t = 0, CM Frame t = 0, Lab Frame Pick-up the first occurrence (t + Dtmin) satisfying the cascade criteria p'2 Pauli-Blocked interaction p2 p'1orp'2(Lab Frame) occupied p1 q p'1 4-vectors updated t = Dtmin, CM Frame p'1andp'2(Lab Frame) available 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 10

  11. Forward angle meson photoproduction in nuclei Elementary photoproduction of pseudoscalar mesons [g +N --> p0(h) + N] THE MODEL Differential cross sections described via a Regge model assuming VDM (r and w exchange) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 11

  12. Forward angle meson photoproduction in nuclei Elementary photoproduction of vector mesons [g +N --> w(r) + N] THE MODEL Regge model includes Pomeron and p-meson exchange amplitudes 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 12

  13. Forward angle meson photoproduction in nuclei p-nucleus Final State Interactions (channels included in the MCMC model) THE MODEL 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 13

  14. Forward angle meson photoproduction in nuclei Energy dependence of p-nucleon scatterings: MCMC model versus PDG THE MODEL 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 14

  15. g p0(h) r, w N N • Forward angle meson photoproduction in nuclei (MCMC*) Incoherent process: g + A--> meson + X THE MODEL Pauli Blocking FSI Normalization and initial sampling of polar angles Photon shadowing g w (r) P, p N N (*) T. E. Rodrigues et al., Phys. Rev. C 82, 024608 (2010) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 15

  16. pseudoscalar mesons Differential cross sections for incoherent p0 photoproduction @ 5.2 GeV (PrimEx kinematics) RESULTS p0 T. E. Rodrigues et al., Phys. Rev. C 82, 024608 (2010). 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 16

  17. pseudoscalar mesons p0 photoproduction yields from PrimEx(MIT/JLab analysis) RESULTS Figures from Dustin Mcnulty Line shapes (MIT/JLab analysis) Coherent: S. Gevorkyan et al., Phys. Rev. C 80, 055201 (2009) Incoherent: T. E. Rodrigues et al., Phys. Rev. C 82, 024608 (2010) p0 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 17

  18. pseudoscalar mesons Revisiting PrimEx data with the latest (state-of-the-art) on coherent photoproduction RESULTS • Coherent: M. Kaskulov and U. Mosel, Phys. Rev. C 84, 065206 (2011) • PrimEx: I. Larin et al., Phys. Rev. Lett. 106, 162303 (2011) • Incoherent: MCMC model scaled by 1.35 ± 0.03 p0 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 18

  19. pseudoscalar mesons Incoherent h photoproduction in Cornell: h --> ggdecay width revisited RESULTS h Cornell: A. Browman et al., Phys. Rev. Lett. 32, 1067 (1974) Calculation: T. E. Rodrigues et al., Phys. Rev. Lett. 101, 012301 (2008) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 19

  20. pseudoscalar mesons Incoherent h photoproduction in Cornell: h --> ggdecay width revisited RESULTS h 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 20

  21. Attenuation of w mesons in nuclei: MCMC versus TAPS measurements (w --> p0g) G. I. Lykasov et. al, Eur. Phys. J. A 6, 71 (1999) • vector mesons RESULTS TAPS measurements are reproduced assuming <s*inel >~ 40 mb w MCMC (previous version): T. E. Rodrigues and J.D.T. Arruda-Neto, Phys. Rev. C 84, 021601 (R) (2011) TAPS: M. Kotulla et al., Phys. Rev. Lett. 100, 192302 (2008) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 21

  22. In-medium w width (nuclear rest frame) from TAPS: MCMC versus Giessen /Valencia models Giessen/Valencia models (r = r0) 130 < G* < 150 MeV MCMC model (r = 0.5r0) <G*>~ 56 MeV Giessen: P. Mühlich and U. Mosel, Nucl. Phys. A773, 156 (2006) Valencia: M. Kaskulov, E. Hernandez, and E. Oset, Eur. Phys. J. A 31, 245 (2007) • vector mesons RESULTS w 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 22

  23. In-medium w width: CLAS(w --> e+e- ) versus TAPS (w --> p0g)measurement s*inel > 150 mb <G*> ~ 56 MeV G* > 200 MeV • vector mesons RESULTS CLAS: M. Wood et al., Phys. Rev. Lett. 105, 112301 (2010) TAPS: M. Kotulla et al., Phys. Rev. Lett. 100, 192302 (2008) Giessen: P. Mühlich and U. Mosel, Nucl. Phys. A773, 156 (2006) Valencia: M. Kaskulov, E. Hernandez, and E. Oset, EPJ A 31, 245 (2007) Glauber: R.J. Glauber and G. Matthiae, Nucl. Phys. B 21, 135 (1970) w 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 23

  24. w r f • vector mesons Attenuation of vector mesons in CLAS revisited (preliminary) RESULTS Constrained and simultaneous fitting of the e+e- invariant mass spectra 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 24

  25. w r f • vector mesons Attenuation of vector mesons:MCMC versus CLAS(preliminary) RESULTS CLAS: M. Wood et al., Phys. Rev. Lett. 105, 112301 (2010) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 25

  26. x 0.94 x 0.90 x 1.3 x 2.3 w • vector mesons w peak after subtraction of r background:MCMC versus CLAS(preliminary) RESULTS GiBUUmodel: M. Effenbergerand U. Mosel, Phys. Rev. C 62, 014605 (2000) MCMCmodel CLAS: M. Wood et al., Phys. Rev. Lett. 105, 112301 (2010) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 26

  27. w • vector mesons In-medium w width and the inelastic wN cross section revisited MCMC versus TAPS/CLAS (preliminary) RESULTS TAPS/CLAS data are mutually consistent with a multiple scattering scenario with <s*inel > ~ 39 mb and <G*>~ 57 MeV. 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 27

  28. vector mesons In-medium w width and inelastic cross section (summary) RESULTS CLAS: M. Wood et al., Phys. Rev. Lett. 105, 112301 (2010) TAPS: M. Kotulla et al., Phys. Rev. Lett. 100, 192302 (2008) Glauber: R.J. Glauber and G. Matthiae, Nucl. Phys. B 21, 135 (1970) Giessen: P. Mühlich and U. Mosel, Nucl. Phys. A773, 156 (2006) Valencia: M. Kaskulov, E. Hernandez, and E. Oset, EPJ A 31, 245 (2007) w 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 28

  29. Conclusions and future prospects • The MCMC model is a suitable framework for the evaluation of the nuclear effects in wide ranges of targets and incident energies. • The calculations of the incoherent cross sections for p0 reproduce with good accuracy the PrimEx data. The fitted parameters obtained for Carbon (0.69 ± 0.05/1.35 ± 0.03) are strongly dependent (factor 2) on the calculations of the coherent part (S. Gevorkyan et al./Kaskulov & Mosel). • Our reanalysis of the h --> gg decay width [0.476(62) keV] is in line with the PDG average [0.510(26) keV] and ~ 50% higher than Cornell’s result [0.324(46) keV]. Future and high precision measurements using the Primakoff method are necessary and could be focused on the proton (constraint), light nuclei (suitable to disentangle the Coulomb peak) and heavy targets (to access the unknown in-medium hN cross section). CONCLUSIONS 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 29

  30. Conclusions and future prospects • The predictions for w mesons with sinel ~40mb reproduce quite well TAPS data, leading to G*~ 56 MeV. This result is considerably lower than the predictions from the Giessen, Valencia and Glauber models (factors 1.3 to 1.5). In the Glauber model, the effects of Fermi motion, Pauli-blocking, coupled-channels, nuclear shadowing and p0 rescattering are neglected. • Recent data from CLAS indicate a much stronger w absorption than TAPS measurements. Calculations using the Giessen, Valencia and Glauber models could not explain this huge absorption even assuming G* > 200 MeV and sinel> 150 mb. Our preliminary analysis of the e+e-IM spectra suggests that both CLAS and TAPS data are mutually consistent with a multiple scattering scenario with sinel ~ 39 mb and G*~ 57 MeV. CONCLUSIONS 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 30

  31. Future plans • Short term: • Delineation of the inelastic background of pseudoscalar mesons in future experiments dedicated to the chiral anomaly of QCD via the Primakoff method: [“Precision measurement of Gh --> gg with the 12 GeV upgrade @ Jlab”, A. Gasparian et al., JLab exp. E1210011, http://www.jlab.org/exp_prog/proposals/10prop.html (2010)] • The investigation of in-medium changes in light vector mesons surrounded by strongly interacting cold nuclear matter (JLab, KEK, Spring-8 and TAPS) • Long term (potentialities/possibilities): • To extend the calculations for Heavy-Ion Collisions • Hadronization mechanism • Color Transparency • Jets in dense and hot nuclear matter • Di-lepton channels in relativistic HI collisions FUTURE PROSPECTS 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 31

  32. Collaborators • João Arruda-Neto (USP, Brazil) • Joel Mesa (UNESP, Brazil) • Cesar Garcia and Katherin Shtejer (CEADEN, Cuba) • Daniel Dale and Philip Cole (ISU/JLab, USA) • Itaru Nakagawa (RIKEN, Japan) Thank you ! 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 32

  33. Extra slides Elementary photoproduction of pseudoscalar mesons (g +N --> p0 + N) THE MODEL Regge model (r and w exchange) plus Regge cuts (absorption due to FSI) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 33

  34. Extra slides Elementary photoproduction of vector mesons (g +N --> r + N) THE MODEL Pomeron plus p-meson exchange amplitudes are included 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 34

  35. Extra slides Parameterization of the total and elastic p0(h)N cross sections THE MODEL 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 35

  36. Extra slides Parameterization of the total and elastic VN cross sections (1) THE MODEL (1)G. I. Lykasov et. al, Eur. Phys. J. A 6, 71 (1999) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 36

  37. Fermi surface Extra slides The non-stochastic Pauli-blocking mechanism THE MODEL py kF Dp px pz MCMC: T.E. Rodrigues et al., PRC 69 064611 (2004) Ref.[7]: J. Cugnon, C. Volant, and S. Vuillier, NPA 620, 475 (1997) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 37

  38. Extra slides RESULTS p0 Calculations of the incoherent cross sections Group I: S. Gevorkyan et al., arXiv:0908.1297 [hep-ph] Group II: T. E. Rodrigues et al., Phys. Rev. C 82, 024608 (2010) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 38

  39. Extra slides Recent developments for coherent photoproduction of pseudoscalar mesons RESULTS Calculation: M. Kaskulov and U. Mosel, Phys. Rev. C 84, 065206 (2011) JLab data: I. Larin et al., Phys. Rev. Lett. 106, 162303 (2011) p0 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 39

  40. Extra slides • pseudoscalar mesons RESULTS Scaling of nuclear cross sections for p0 photoproduction within 3 to 9 GeV (Cornell versus MCMC) MCMC: T. E. Rodrigues et al., Phys. Rev. C 82, 024608 (2010) p0 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 40

  41. Extra slides • pseudoscalar mesons RESULTS Scaling of nuclear cross sections for p0 photoproduction within 3 to 9 GeV (Cornell versus MCMC) MCMC: T. E. Rodrigues et al., Phys. Rev. C 82, 024608 (2010) p0 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 41

  42. Extra slides • pseudoscalar mesons RESULTS Scaling of nuclear cross sections for p0 photoproduction within 3 to 9 GeV (Cornell versus MCMC) MCMC: T. E. Rodrigues et al., Phys. Rev. C 82, 024608 (2010) Cornell: W. T. Meyer et al., Phys. Rev. Lett. 28, 1344 (1972) p0 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 42

  43. Extra slides • pseudoscalar mesons RESULTS Scaling of nuclear cross sections for p0 photoproduction within 3 to 9 GeV (Cornell versus MCMC) MCMC: T. E. Rodrigues et al., Phys. Rev. C 82, 024608 (2010) Cornell: W. T. Meyer et al., Phys. Rev. Lett. 28, 1344 (1972) p0 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 43

  44. Extra slides Future prospects for the h --> ggdecay width RESULTS Precision measurement of Gh --> ggwith the 12 GeV upgrade @ JLab A. Gasparian et al., JLab exp. E1210011 (proton and 4-He targets) http://www.jlab.org/exp_prog/proposals/10prop.html (2010) Potentialities of measurements in complex nuclei (Coherent/Incoherent contributions accurately constrained by calculations) h K.M.: M. Kaskulov and U. Mosel, Phys. Rev. C 84, 065206 (2011) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 44

  45. ~1 mb ~20 mb Extra slides Extracting shN via nuclear measurements beyond the coherent peak! RESULTS • Heavy targets:preferable to access the hN cross section • (multiple scattering scenario) • Light targets:preferable to extract Gh --> gg • (high Z2 in comparison with proton and 4-He) • [lower model dependence in comparison with heavy targets, where the Coulomb (qpeak ~ mP2/2k2) and NC cross sections (qpeak ~ 2/kR) are more strongly correlated (form factor effect)] h 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 45

  46. Extra slides Double differential cross sections for incoherent p0 photoproduction RESULTS p0 T. E. Rodrigues et al., Phys. Rev. C 82, 024608 (2010). 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 46

  47. h polar angles (mrad) Extra slides Cornell´s analysis* Our reanalysis** Coulomb (~ Gh --> gg) Nuclear Incoherent Isotropic NI Background without PB (T A0.75) NI Background from MCMC model *A. Browman et al., Phys. Rev. Lett. 32, 1067 (1974) **T. E. Rodrigues et al., Phys. Rev. Lett. 101, 012301 (2008) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 47

  48. Extra Extra slides Momentum dependent w transparency ratios:TAPS versus MCMC RESULTS Effect of Pauli-blocking for low <pw> and high elastic cross section (<r> ~ 0.4) w TAPS: M. Kotulla et al., Phys. Rev. Lett. 100, 192302 (2008) MCMC: T. E. Rodrigues and J.D.T. Arruda-Neto, Phys. Rev. C 84, 021601 (R) (2011) 8/20/2014 Tulio Rodrigues – NN2012 – San Antonio – USA 48

  49. g h (p0) r, w N N Cross section expanded in t-channel helicity amplitudes* (Fi) Calculated using a Regge model (r and w exhange) plus Reggeon cuts** (*) A. Gasparian and S. Gevorkyan, Theoretical part of PrimEx, 2004. (**) M. Braunschweig et al., Nucl. Phys. B 20, 191 (1970). Extra slides The elementary meson photoproduction: g +N --> h(p0) + N The cascade “trigger” THE MODEL Tulio Rodrigues – NN2012 – San Antonio – USA

  50. Extra slides Contribution of Regge cuts on the incoherent cross section Tulio Rodrigues – NN2012 – San Antonio – USA

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