Hadron Propagation and Color Transparency at 12 GeV

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1 Hadron Propagation and Color Transparency at 12 GeV Dipangkar Dutta Mississippi State University Hall C Users Meeting Jan 21-22, 2016 Hall C meeting Jan 2016 D. Dutta Hadron propagation in nuclear medium 1 /24

2 Outline! Nuclear Transparency and Hadron Propagation! Color Transparency & Small size configurations! CT and soft-hard factorization/gpds! (e,e p) experiment as a commissioning experiment! Summary Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 2 /24

3 Hadron Propagation through nuclear matter is a key element of the nuclear many body problem. Needed for interpretation of experiments involving hadrons in the nuclear matter and searches for QCD in nuclei. An active area of interest. N. C. R. Makins et al. PRL 72, 1986 (1994) (cited 153 times); K. Garrow et al. PRC 66, (2002) (cited 92 times); B. Clasie et al. PRL (2007) (cited 59 times) L. El-Fassi et al. PLB 712, 326 (2014) (cited 15 times) At high energies it is dominated by reduction of flux, which is quantified by Nuclear Transparency. Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 3 /24

4 Nuclear Transparency is the ratio of cross-sections for exclusive processes from nuclei to nucleons. = free (nucleon) cross-section parameterized as = Fit to α = , for π, K, p Hadron momentum 60, 200, 250 GeV/c α σ Ν Hadron Nucleus total cross-section Κ A. S. Carroll et al. Phys. Lett 80B 319 (1979) π p -- p T = A α σ Ν (µb) α < 1 interpreted as due to the strong interaction nature of the probe Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 4 /24

5 Nuclear Transparency is expected to be energy independent. 1.0 T Traditional NP calculations 2.0 Energy (GeV) 10.0 Ingredients σ hν h-n cross-section Glauber multiple scattering approximation Correlations & FSI effects. For light nuclei very precise calculations of are possible. Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 5 /24

6 Nuclear Transparency is expected to be energy independent. 1.0 T Traditional NP calculations 2.0 Energy (GeV) 10.0 N-N cross-section is energy independent Ingredients σ hν h-n cross-section Glauber multiple scattering approximation Correlations & FSI effects. For light nuclei very precise calculations are possible. pp scatt. cross-section pn scatt. cross-section Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 6 /24

7 Nuclear Transparency is expected to be energy independent. 1.0 T Traditional NP calculations 2.0 Energy (GeV) 10.0 N-N cross-section is energy independent Ingredients σ hν h-n cross-section Glauber multiple scattering approximation Correlations & FSI effects. For light nuclei very precise calculations of are possible. All other reaction mechanisms are energy independent! pp scatt. cross-section pn scatt. cross-section Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 7 /24

8 Color Transparency is the result of squeezing and freezing. At high momentum transfers, scattering takes place via selection of amplitudes characterized by small transverse size (PLC) - squeezing The compact size is maintained while traversing the nuclear medium - freezing. The PLC is color screened - it passes undisturbed through the nuclear medium. Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 8 /24

9 Color Transparency is a color coherence property of QCD. CT leads to vanishing of the hadron-nucleon interaction for hadrons produced at high momentum transfers CT is unexpected in a strongly interacting hadronic picture. But it is natural in a quark-gluon framework. CT is well established at high energies (DIS data cannot be described without assuming CT). The onset of CT is of primary interest. Onset of CT would be a signature of the onset of QCD degrees of freedom in nuclei Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 9 /24

10 Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 10 /24 CT is also connected to the new framework of GPDs developed in the last two decades. The new framework, assumes the dominance of the handbag mechanism. -factorizes into a hard interaction with a single quark and a soft part parametrized as GPDs. Factorization theorems have been derived for deep-exclusive processes and are essential to access GPDs Recent DVCS and wide angle Compton scattering results disagree with pqcd predictions but are consistent with the dominance of handbag mechanism.

11 Factorization is not rigorously possible without the onset of CT Meson distribution amplitude calculable in pqcd small size configurations (SSC/PLC) needed for factorization: It is still uncertain at what Q 2 value reaches the factorization regime The onset of CT is a necessary (but not sufficient) conditions for factorization. -Strikman, Frankfurt, Miller and Sargsian Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 11 /24

12 CT is well established at high energies. Coherent diffractive dissociation of 500 GeV/c pions on Pt and C. π + A (2 jets) + A 2 Q 2 = 7 (GeV 2 ) Q 2 = 10 (GeV 2 ) Q 2 = 20 (GeV 2 ) 1.5 α with CT 1 without CT k T JET (GeV) Aitala et al., PRL 86, 4773 (2001) Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 12 /24

13 CT is well established at high energies. Vector Meson production at large Q 2 at HERA dσ/dt e - bt b (GeV -2 ) ZEUS ρ 0 ZEUS J/ψ FKS ρ 0 8 FKS J/ψ Convergence of the t-slope of ρ and J/ψ electroproduction at large Q 2 predicted by the presence of small size qq-bar state Q 2 (GeV 2 ) Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 13 /24

14 No Evidence for CT at intermediate energies is a mixed bag. First direct search for the onset of CT Transparency in A(p,2p) Reaction at BNL PRL 87, (2001) PRL 81, 5085 (1998) PRL 61, 1698 (1988) Solid line is fit to 1/oscillation in p-p scattering data Shaded band Glauber calculation Results inconsistent with CT only. But can be explained by including additional mechanisms such as nuclear filtering or charm resonance states. Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 14 /24

15 Evidence for CT at intermediate energies is a mixed bag. A(e,e'p) results Q 2 dependence consistent with standard nuclear physics calculations Solid Pts JLab Open Pts -- other Constant value fit for Q 2 > 2 (GeV/c) 2 has χ 2 / df 1 N. C. R. Makins et al. PRL 72, 1986 (1994) G. Garino et al. PRC 45, 780 (1992) D. Abbott et al. PRL 80, 5072 (1998) K. Garrow et al. PRC 66, (2002) Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 15 /24

16 JLab Experiments conclusively find the onset of CT. A(e,e' π + ) A(e,e' ρ 0 ) Hall-C Experiment E pion electroproduction from nuclei found an enhancement in transparency with increasing Q 2 & A, consistent with the prediction of CT. (X. Qian et al., PRC81: (2010), B. Clasie et al, PRL99: (2007)) CLAS Experiment E rho electroproduction from nuclei found a similar enhancement, consistent with the same predictions (L. El-Fassi, et al., PLB 712, 326 (2012) ) FMS: Frankfurt, Miller and Strikman, Phys. Rev., C78: , 2008 Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 16 /24

17 Experiment E : 11 GeV, will provide answers. A(e,e 11 GeV JLab (spokespersons: R. Ent & D. Dutta ) Can help interpret the rise seen in the BNL A(p,2p) data at P p = 6-9 GeV/c PRC 45, 791 (1992) PRC 51, 3435 (95), 50, R1296 (94) PRC 74, R (2007) P p (GeV/c) Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 17/24

18 Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 18 /24 (p,2p) results are related to oscillations in p-p cross sections. PRL 87, (2001) PRL 81, 5085 (1998) PRL 61, 1698 (1988) Solid line is fit to 1/oscillation in p-p scattering data Shaded band Glauber calculation

19 Experiment E is one of the commissioning experiments. A(e,e 11 GeV JLab A(e,e p) cross-section on 1 H and 12 C with 80uA of 8.8 & 11.0 GeV beam. 5 different Q 2 points (8,10, 12, 14 & 16.4 GeV 2 ) Total beam time requested for A(e,e'p) = 235 hrs ~ 10 days (for 10 cm LH2) Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 19/24

20 Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 20 /24 Requirements for the spectrometers and target are middle of the road. 10 HMS: p = GeV/c θ = deg SHMS: p = GeV/c θ = deg

21 A(e,e p) is an ideal commissioning experiment. Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 21 /24

22 Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 22 /24 A(e,e p) is an ideal commissioning experiment. The version simulations and analysis package was able to monitor rates online at the 10% level. We should be able to do much better now and provide a great diagnostic tool for commissioning.

23 Possible run plan for the commissioning experiment. E measured C(e,e p) at Q 2 = 8.1 GeV 2 this is same as the lowest point for E We are currently using this data to test the new Hall-C analyzer and SIMC. This kinematics is ideal to begin the commissioning experiment Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 23 /24

24 Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 24 /24 Summary Measurement of hadron transparencies provides an understanding of the propagation of highly energetic particles through the nuclear matter. By comparing exclusive processes on both nucleons and nuclei, one of the signatures of the transition from quarks to hadrons - namely color transparency can be studied. Proton transparency data can be well described by conventional nuclear physics. These studies will be extended to higher energies at the upgraded JLab. The range in Q 2 covered by the A(e,e p) experiment will have significant overlap with the BNL A(p,2p) experiment and will help interpret the rise in transparency observed in the BNL experiment.

25 Oscillations in p-p cross sections with energy is well known. RI s 10 (dσ/dt) data from Landshoff and Polkinghorne D.Dutta and H. Gao, PRC 71, R (2005) Hall C Meeting, Jan 2016 D. Dutta Hadron propagation in nuclear medium 25 /24