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The EMC Effect Cannot Be Explained by Conventional Nuclear Physics

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The EMC Effect Cannot Be Explained by Conventional Nuclear Physics "Beam in 30 minutes or it's free" [S. Kuhn, S. Strauch, J. Watson] [D. Dutta] [W. Brooks] [P. Bosted] John Arrington Argonne National Lab "The next seven years..." production ψ 1 - The EMC effect and related measurements 2 - Color Transparency 3 - Quark propagation 4 - J/ Nucleons in the Nuclear Environment Jefferson Lab User's Group Annual Meeting, June 18, 2004 Topic: Study of nucleons (hadrons, quarks) in nuclei "Beam in 30 minutes or it's free" John Arrington , matter is hadrons Argonne National Lab "The next seven years..." real world In the lab (GeV accelerators), matter is quarks In the How do nucleons interact with the nucleus? How do other (exotic?) hadrons interact with the nucleus? How do quarks interact with the nucleus? Nucleons in the Nuclear Environment Jefferson Lab User's Group Annual Meeting, June 18, 2004 Questions for JLab: Bigger question: Does QCD matter in the real world? [fm] r 2.5 r [fm] 2.0 two quarks two nucleons 1.5 Potential between potential between 1.0 0.5 ~1 fm 0 1.2 0.4 2.0 1.6 0.8 -0.4 -0.8 0 V(r) V(r) [GeV] 18 tons! times the coulomb 12 Two "Realms" of Nuclear Physics 1 GeV/cm = >10 attraction in hydrogen Matter consists of colorless bound states of QCD Strongly attractive at all distances: Quark interactions cancel at large distances, making the interactions of hadrons finite. Don't observe quarks, gluons, or color in traditional nuclear physics Quarks have been swept under a very heavy (18 ton) rug QCD land quarks + gluons color Real world nucleons + mesons strong interaction 8 5 JLAB12 2 neutron stars deconfinement chiral restoration ) 3 plasma 1 quark-gluon SIS nuclei atomic AGS chemical freeze-out SPS hadron gas 0.3 RHIC LHC thermal freeze-out NET BARYON DENSITY (0.17 GeV/fm early universe 50 250 200 150 100 temperature T (MeV) T temperature When do quarks matter? The Iceberg see density-dependent effects in nuclear structure (EMC effect) The shifting an 18 ton weight by dropping the titanic on top of it do Titanic ≅ We Do these effects have anything to do with the quarks? To peek under the rug, we have to shift 18 ton weight at least a little bit CERN (titanic=13550 tons=700 GeV, (some sites, 20-40ktons) iceberg=150k-300k tonnes (8-16 TeV), SLAC=50GeV=900 Tons). SUV=2-3 (some 4) tons. 747=435 Cosmic rays SLAC, DESY, LHC... Early universe RHIC? Neutron stars Nuclei?? JLab???? High energy High temperatures High densities ) Copper ( Iron EMC effect for most recently - J. Smith and G. A. Miller, PRC 65:015211 (2002) most recently - J. Rozynek and G. Wilk, NPA 721, 388 (2003) Medium modifications to nucleon structure? The EMC effect cannot be explained by conventional nuclear physics... Unless it can be explained by conventional nuclear physics. Depletion of the structure function for 0.3<x<0.8 The magnitude of the effect increases with size/density The x-dependence is identical for all nuclei It has been clear for some time that binding, Fermi motion play important roles. Do we need something more than conventional nuclear physics? Recently shown that... arXiv:nucl-th/0208039 v1 21 Aug 2002 2002 Aug Aug 21 21 v1 v1 arXiv:nucl-th/0208039 arXiv:nucl-th/0208039 most recently - J. Smith and G. A. Miller, PRC 65:015211 (2002) most recently - J. Rozynek and G. Wilk, NPA 721, 388 (2003) J. Jourdan, NPA 603, 117 (1996) J. Carlson et al., PLB 553, 191 (2003) What else do we know about medium modifications? Quasielastic response is (basically) nothing more than nucleon elastic scattering + nucleon distribution in nucleus The EMC effect cannot be explained by conventional nuclear physics... Unless it can be explained by conventional nuclear physics The Coulomb Sum Rule is fulfilled... 1200 b) a) 1100 600 500 (MeV/c) 400 eff q 300 Pb Pb Ca Ca Fe Ca Fe Fe Fe He He 3 3 40 48 56 208 40 56 208 56 56 Fig. 6 200 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.4 1.1 1.0 0.9 0.8 0.7 0.6 0.5 eff L S ) (q most recently - J. Smith and G. A. Miller, PRC 65:015211 (2002) most recently - J. Rozynek and G. Wilk, NPA 721, 388 (2003) J. Jourdan, NPA 603, 117 (1996) J. Carlson et al., PLB 553, 191 (2003) J. Morgenstern, Z.-E. Meziani, PLB 515, 269 (2001) What else do we know about medium modifications? Integrated quasielastic response suppressed by ~30-40% The EMC effect cannot be explained by conventional nuclear physics... Unless it can be explained by conventional nuclear physics The Coulomb Sum Rule is fulfilled... Except that maybe it isn't. most recently - J. Smith and G. A. Miller, PRC 65:015211 (2002) most recently - J. Rozynek and G. Wilk, NPA 721, 388 (2003) J. Jourdan, NPA 603, 117 (1996) J. Calrson et al., PLB 553, 191 (2003) J. Morgenstern, Z.-E. Meziani, PLB 515, 269 (2001) G. Van der Steenhoven, et al., PRL 57, 182 (1986) [form factor ratio in nuclei] modified for nucleons in a nucleus What else do we know about medium modifications? M /G E G The EMC effect cannot be explained by conventional nuclear physics... Unless it can be explained by conventional nuclear physics The Coulomb Sum Rule is fulfilled... Except that maybe it isn't. Nucleon form factors are modified in nuclei... END? DEAD most recently - J. Smith and G. A. Miller, PRC 65:015211 (2002) most recently - J. Rozynek and G. Wilk, NPA 721, 388 (2003) J. Jourdan, NPA 603, 117 (1996) J. Carlson et al., PLB 553, 191 (2003) J. Morgenstern, Z.-E. Meziani, PLB 515, 269 (2001) G. Van der Steenhoven, et al., PRL 57, 182 (1986) [form factor ratio in nuclei] T. D. Cohen, J.W. Van Orden, A. Picklesimer, PRL 59, 1267 (1987) [form factor ratio in nuclei] I. Sick, NPA 434, 677 (1985) R.W. McKeown, PRL 56, 1452 (1986) [y-scaling limits] What else do we know about medium modifications? The EMC effect cannot be explained by conventional nuclear physics... Unless it can be explained by conventional nuclear physics The Coulomb Sum Rule is fulfilled... Except that maybe it isn't. Nucleon form factors are modified in nuclei... Unless they aren't. hard small very complicated about medium modifications? most recently - J. Smith and G. A. Miller, PRC 65:015211 (2002) most recently - J. Rozynek and G. Wilk, NPA 721, 388 (2003) The effects are really know The experiments are Jefferson Lab needs to do more The theory is than just improve a few measurements... J. Jourdan, NPA 603, 117 (1996) J. Carlson et al., PLB 553, 191 (2003) J. Morgenstern, Z.-E. Meziani, PLB 515, 269 (2001) G. Van der Steenhoven, et al., PRL 57, 182 (1986) [form factor ratio in nuclei] T. D. Cohen, J.W. Van Orden, A. Picklesimer, PRL 59, 1267 (1987) [form factor ratio in nuclei] I. Sick, NPA 434, 677 (1985) R.W. McKeown, PRL 56, 1452 (1986) [y-scaling limits] What do we The EMC effect cannot be explained by conventional nuclear physics... Unless it can be explained by conventional nuclear physics The Coulomb Sum Rule is fulfilled... Except that maybe it isn't. Nucleon form factors are modified in nuclei... Unless they aren't. density local (better facility) (better techniques) (brand new ideas) What can Jefferson Lab do? EMC effect Coulomb sum rule y-scaling limits on nucleon `swelling' Form factor modification by polarization transfer Measure EMC effect as a function of Probe high-density components of nucleus (SRCs) 1) Improve a few measurements 2) Make new measurements 3) Invent new techniques 2 < 3.0 2 4 GeV ≅ 2 1.2 < W Q EMC effect in the resonance region Indication of different shape for Carbon at large x EMC effect - purely hadronic? Consequence of precise duality? E89-008 (4 GeV) - Relaxing the DIS limit appears to yield identical results, with improved precision at large x Any deviation from the DIS result should be even smaller at 6 GeV Identical nuclear dependence in DIS and resonance regimes! E01-001, Hall C, September 2004 He 4 heavy nuclei He) and 3 He: 4 He 3 SLAC fit to (scaled to He and 3 > ? A <ρ Calculations by Pandharipande and Benhar for He will provide a new way to test the existing models 4 EMC effect in very light nuclei He, x-dependence same for all nuclei? 3 (D) - Vary with A or 2 (A)/F 2 F New measurements planned for Provide more information on the A-dependence Allow comparison to models in exact few-body calculations The shape in T σ / L σ [E04-001] A [E99-118] ? 2 and R= 2 and R Preliminary and F L from JLab [also E94-110, E00-002] p [E02-109] R D Are nuclear effects identical in F from HERMES D /R A R Extending EMC effect measurements to F Additional experiments approved to measure R Probe nucleons! 30-35% (e.g. y-scaling limits) 2 at large Q as a consequence (or cause) of the EMC effect E technique 15-20% Beyond "The EMC Effect" nucleon form factors polarization transfer - Almost no sensitivity to G - Nuclear effects large for quasielastic cross section measurements Some models, e.g. Quark-Meson Coupling model (Thomas, et al.), predict modified If nucleon modification explains the EMC effect, why probe nuclei? Previous attempts to look for nucleon form factor modification had mixed results JLab luminosity, polarization, polarimetry --> Study in-medium form factors using the of a free proton M He /G 3 E He(e,e'p) 4 of a bound proton to G M /G E Polarization transfer in Indication of modified form factors in a nucleus E03-104 approved by PAC24 to make additional, high precision measurements [S.
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