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HADRONIC PHYSICS IN SPAIN

HADRONIC PHYSICS IN SPAIN. NUPECC meeting Madrid (Spain), March 7, 2008. Topics: Chiral Perturbation Theory QCD Sum Rules Effective Field Theory Exotic Hadrons Hadron Properties from Lattice Experimental Results and Future Perspectives Hadronic Distribution Amplitudes.

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HADRONIC PHYSICS IN SPAIN

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  1. HADRONIC PHYSICS IN SPAIN NUPECC meeting Madrid (Spain), March 7, 2008

  2. Topics: Chiral Perturbation TheoryQCD Sum RulesEffective Field TheoryExotic HadronsHadron Properties from LatticeExperimental Results and Future PerspectivesHadronic Distribution Amplitudes Spectroscopy of light and heavy quark mesonsBaryonsQuarkoniaGlueballs, hybrids and multiquarksPhenomenological modelsEffective lagrangiansQCD on the latticeHadrons in matterHeavy ion collisionsFuture facilities

  3. Define Hadronic physics, 1 o 2 slides

  4. Theory Experiment

  5. We fit our 12 free parameters to 370 data points and their reproduction from ππ threshold up to 2 GeV is fair as shown in Fig.1. The width of the band represents our systematic uncertainties at the level of two standard deviations. The fitted data are from left to right and top to bottom, ππ I = 0 S-wave phase shifts δ0 0, the elasticity parameter η0 0 = |S11|, the I = 0 S-wave ππ → K ¯K phase shifts δ1,2, |S1,2|, the S-wave contribution to the ππ → ηη event distribution and the event distribution for ππ → ηη′. The last two panels corresponds to the phase (φ) and modulus (A) of the K−π+ → K−π+ amplitude from the LASS data. Compared with other works we determine the interaction kernels from standard chiral Lagrangians, avoiding ad-hoc parameterizations.

  6. The investigation of hadron properties inside nuclear matter at normal and high densities and temperatures is one of the main goals of current nuclear physics studies. Hadron induced reactions on heavy nuclei (e.g. Au, Pb) are the proper tool to probe particle properties in long-living ground state nuclear matter. Heavy ion collisions at energies of 1-2 AGeV can be used to create a reaction region of increased density for as long as 10 fm/c. Under these conditions, considerable modifications of basic hadron properties (masses, decay widths, etc.) are expected and probably can be verified for the first time experimentally by high resolution lepton pair decay measurements. In order to investigate this phenomenon, the electron-positron pair spectrometerHADES was set up, and is in operation, at GSI by an international collaboration of 17 institutions from 9 European countries. Departamento de Física de Partículas, University of Santiago de Compostela , Santiago de Compostela, Spain D. Belver   P. Cabanelas   E. Castro   J. A. Garzón Instituto de Física Corpuscular, Universidad de Valencia-CSIC , Valencia, Spain J. Díaz   A. Gil  

  7. SPAIN, MADRID, CIEMAT; TL&CP: Pedro LADRON DE GUEVARA SPAIN, SANTIAGO DE COMPOSTELA, UNIVERSIDAD DE SANTIAGO DE COMPOSTELA; TL&CP: Carlos PAJARES

  8. in-medium modifications of hadrons in dense matter. indications of the deconfinement phase transition at high baryon densities. the critical point providing direct evidence for a phase boundary. exotic states of matter such as condensates of strange particles. The approach of the CBM experiment towards these goals is to measure simultaneously observables which are sensitive to high density effects and phase transitions (see figure 2 for an illustration). In particular, the research program is focused on the investigation of: short-lived light vector mesons (e.g. the ρ-meson) which decay into electron-positron pairs. These penetrating probes carry undistorted information from the dense fireball. strange particles, in particular baryons (anti-baryons) containing more than one strange (anti-strange) quark, so called multistrange hyperons (Λ, Ξ, Ω). mesons containing charm or anti-charm quarks (D, J/Ψ). collective flow of all observed particles. event-by-event fluctuations.

  9. Resonance physics in chiral unitary approaches A. Ramos (University of Barcelona) Workshop on the physics of excited nucleons (NSTAR 2007) 5-8 September 2007 Bonn, Germany

  10. Outline: Chiral unitary model The L(1405) and its two-pole nature Other sectors: eg S=-2 X resonances Heavy flavored baryon resonances

  11. K N scattering: a lively topic • K N scattering in the I=0 channel is dominated by the presence of the L(1405), located only 27 MeV below the K N threshold • Already in the late sixties, Dalitz, Wong and Rajasekaran [Phys. Rev. 153 (1967) 1617] obtained the L(1405) as a KN quasi-bound state in a potential model (Scrhoedinger equation). • The study of KN scattering has been revisited more recently from the modern view of chiral Lagrangians. However, the presence of a resonance makes cPT not applicable  non-perturbative techniques implementing unitarization in coupled channels are mandatory!

  12. = + Mi Mj s-wave Vij = Bj Bi omitted  next-to-leading order: L2 KN pL pS hL hS KX (MeV) 1255 1331 1435 1663 1741 1814 Chiral Unitary Model: • Build a transition potential V from the meson-baryon Lagrangian at lowest order M B coupled channels for S=-1: Pioneer work: N.Kaiser,P.B.Siegel,W.Weise, Nucl.Phys.A594 (1995) 325 • 2. Unitarization: N/D method • equivalent to Bethe-Salpeter coupled-channel equations with on-shell amplitudes Tij = Vij + Vil GlTlj

  13. Loop function Cut-off regularization (as in E. Oset and A. Ramos, Nucl. Phys. A635 (1998) 99): Dimensional regularization (as in J.A. Oller and U.G. Meissner, Phys. Lett. B500 (2001) 263 ):  subtraction constants of “natural size” (equivalent to cut-off L ~ 1 GeV)

  14. K-p low energy scattering properties and the L(1405) Ladjusted to reproduce branching ratios: L=630 MeV(f=1.15fp) • 2.32 • 0.627 • 0.213 (1.04 without hL, hS) E. Oset and A. Ramos, NPA635 (1998) 99 • hY channels are necessary to: • obtain a good description of the threshold branching ratios (especially g)  preserve SU(3) symmetry Invariant pS mass distribution

  15. Elastic and inelastic cross sections Total cross sections p-waves also included (D.Jido, E.Oset, A.Ramos, PRC66 (2002) 055203) + L,S,S* Differential cross sections

  16. Since the pioneering work of Kaiser, Siegel and Weise [Nucl. Phys. A594 (1995) 325] many other chiral coupled channel models have been developed. E. Oset and A. Ramos, Nucl. Phys. A635 (1998) 99 J.A. Oller and U.G. Meissner, Phys. Lett. B500 (2001) 263 M.F.M. Lutz, E.E. Kolomeitsev, Nucl. Phys. A700 (2002) 193 C.Garcia-Recio et al., Phys. Rev. D (2003) 07009 M.F.M. Lutz, E.E. Kolomeitsev, Nucl. Phys. A700 (2002) 193 B.Borasoy, R. Nissler, and W. Weise, Phys. Rev. Lett. 94, 213401 (2005); Eur. Phys. J. A25, 79 (2005) J.A. Oller, J. Prades, and M. Verbeni, Phys. Rev. Lett. 95, 172502 (2005) J. A.Oller, Eur. Phys. J. A28, 63 (2006) B. Borasoy, U. G. Meissner and R. Nissler, Phys. Rev. C74, 055201 (2006). more channels, next-to-leading order, Born terms beyond WT (s-channel, u-channel), Fits including new data …

  17. The two-pole structure of the L(1405) attractive 1 8a 8s 10 10 27 D. Jido, J.A. Oller, E.Oset, A.Ramos, U.G. Meissner, Nucl. Phys. A725 (2003) 181 C. Garcia-Recio, J.Nieves, M.Lutz, Phys. Lett. B582 (2004) 49 The meson-baryon states built from the 0- pseudoscalar meson octet and the 1/2+ baryon octet can be classified into SU(3) multiplets: 8X 8=1 + 8s + 8a + 10 + 10 + 27 meson Xbaryon In the SU(3) basis: Taking common baryon and meson masses (Mi~M0, mi~m0)in both Vij and Gl one obtains a SU(3) symmetric Tij  a singlet(1)and two degenerate octets(8s,8a)of Jp=1/2- bound states appear!

  18. Breaking SU(3) gradually Mi(x) = M0+ x (Mi-M0) up to the physical masses: m2i(x) = m20 + x (m2i-m20) x=0.(0.1)1 ai(x) = a0 + x (ai-a0) M0= 1151 MeV m0 = 368 MeV a0 = -2.148 S=-1 sector s In I=0, the evolved octet and the evolved singlet appear very nearby:  The nominal L(1405) is the reflection of two poles of the T-matrix !

  19. S=-1 poles and couplings to physical states with I=0 The properties of the L(1405) will depend on which amplitude initiates the reaction! |T|2pcm TKN pS selects preferentially the higher energy (narrower) pole TpSpSselects preferentially the lower energy (wider) pole

  20. Experimental evidence K-pp0p0S0 S. Prakhov et al., Phys.Rev. C70, 034605 (2004) p-pK0pS D.W.Thomas et al. Nucl. Phys. B56, 15 (1973)

  21. + confirmed by models! p-pK0pS K-pp0p0S0 T.Hyodo, et al, Phys. Rev. C68 (2003) 065203 V. K. Magas, E. Oset and A. Ramos, Phys. Rev. Lett. 95, 052301 (2005) where: dominated by the amplitude TKNpS The N*(1710) mechanism stresses the role of TpSpS The chiral terms stress the role of TKNpS MI ~ 1420 MeV

  22. Other sectors JP=1/2- S=0  N*(1535) N. Kaiser, P.B. Siegel, W. Weise, Phys. Lett. B362 (1995) 23 J.C. Nacher et al., Nucl. Phys. A678 (2000) 187 T. Inoue, E. Oset, M.J. Vicente-Vacas, Phys. Rev. C65 (2002) 035204 J. Nieves and E. Ruiz Arriola, Phys. Rev. D64 (2001) 116008 M.F.M. Lutz, E.E. Kolomeitsev, Nucl. Phys. A730 (2004) 110 … S=-2  X(1620), X(1690) A. Ramos, E. Oset, C. Bennhold, Phys. Rev. Lett. 89 (2002) 252001 C. Garcia-Recio, J.Nieves, M.Lutz, Phys. Lett. B582 (2004) 49 JP=3/2-  D(1700),L(1520),S(1670),X(1820) (Interaction of the 0- meson octet with the 3/2+ baryon decuplet) E.E. Kolomeitsev, M.F.M. Lutz, Phys. Lett. B585 (2004) 243 S. Sarkar, E. Oset, M.J. Vicente-Vacas, Phys. Rev. C72 (2005) 015206 L. Roca, S. Sarkar, V.K. Magas and E. Oset, Phys. Rev. C73 (2006) 045208 M. Döring, E. Oset, D. Strottman, Phys. Rev. C73 (2006) 045209 M. Döring, E. Oset, D. Strottman, Phys. Lett. B639 (2006) 59

  23. S=-2 Experimental situation: p-wave:X(1530)****I=1/2 JP=3/2+ s-wave:X(1620)*, X(1690)***I=1/2 JP:not measured X(1620)G = 20 – 50 MeV (intopXstates) (seen recently at CLAS in the g p  p- K+ K- (Xp) reaction) X(1690)G = 10 – 50 MeV (intoKS, KL, pXstates) 1 : 1/3 : 1/10 We looked for dynamical resonances in the S=-2 sector, by solving the unitary coupled channel problem with the states: pX, KL, KS, hX A. Ramos, E. Oset, C. Bennhold, Phys. Rev. Lett. 89 (2002) 252001 Taking: apX=-3.1 aKL=-1.0 aKS=-2.0 ahX=-2.0 • We identify this resonance with theX(1620)* • JP=1/2-can be assigned! (of natural size)

  24. pX invariant mass distribution ~50 MeV KL threshold: 1611 MeV • The “apparent” width (~50 MeV) is much smaller than the actual width at the pole position (~130 MeV) • (Flatté effect: resonance just below a threshold to which the resonance couples strongly)

  25. Heavy flavoured baryon resonances In the charm sector we find a resonance. the Lc(2593) (udc), that bears a strong ressemblance to the L(1405) (uds) in KN dynamics • Can we generate theLc(2593) dynamically fromDN dynamics? • The DN interaction is intimately connected to the properties of the D-meson in a nuclear medium

  26. Understanding the interaction of charmed mesons in a hadronic medium is an important issue: • It is produced in pairs (D+,D-) • in heavy ion experiments: • or antiproton anhilation experiments (PANDA at FAIR) on protons and nuclei: There are hints that a D Dbar meson-pair could feel attraction: an open charm enhancement has been observed in nucleus-nucleus collisions by the NA50 Collaboration If the mass of the D (and Dbar) mesons gets reduced appreciably in the medium (cold or hot), this would provide a conventional hadronic physics explanation to explain J/Y supression (attributed to be a signal for the formation of a Quark-Gluon Plasma)

  27. QCD sum rule (QCDSR) The in-medium mass shift is obtained in the low density approximation from the product of the mass of the charmed quark (mc) and the light meson q-qbar condensate: A. Hayashigashi, Phys. Let. B487, 96 (2000) P. Morath, W. Weise, S.H. Lee, 17 Autumn school on QCD, Lisbon 1999 (World Scientific, SIngapore, 2001) 2001

  28. Nuclear Mean Field approach (NMFA) D-meson self-energy is calculated by supplementing the contribution of the free meson-baryon lagrangian: with additional terms describing the interaction of the D with mean scalar(s) and vector(w) density-dependent meson fields A.Mishra, E.L. Brakovskaya, J. Schaffner-Bielich, S. Schramm, and H. Stoecker, Phys. Rev. C 70, 044904 (2004) Variety of results, depending on ingredients of the model and its parameters:

  29. Quark Meson Coupling approach Hadron interactions mediated by the exchange of scalar-isoscalar (s) and vector (r and w) medium modified mesons among the light constituent quarks. A.Sibirtsev, K.Tsushima, and A.W.Thomas, Eur. Phys. J. A6, 351 (1999) These models predict a substantial reduction of the D-meson mass to which a scalar-isoscalar attraction appears to play an important role However, the full dynamics of the DN interaction (e.g. coupled channels) might be crucial (due to the presence of the Lc(2593) (udc)

  30. Earlier attempts of coupled-channel calculations of the DN amplitude L. Tolós, J. Schaffner-Bielich, and A. Mishra, Phys. Rev.C 70, 025203 (2004) (T=0 MeV) L. Tolós, J. Schaffner-Bielich, and H. Stöcker, Phys. Lett. B635, 85 (2006) (finite T) Channels for C=1, S=0 • Exploits the similarity between L(1495) and Lc(2593): s replaced by c in a SU(3) chiral invariant model (only channels with non-strange hadrons) • The Lc(2593) is generated as a DN s-wave molecular state having a width of 3 MeV M.F.M.Lutz and E.E.Kolomeitsev, Nucl. Phys. A730, 110 (2004) Scattering of Goldstone bosons (p,K, h) off ground state charmed baryons (Lc, Sc …). Proper symmetries respected but noDN, DsY channels I=0, C=1 resonance found at 2650 MeV that couples strongly topSc(very large width ~80 MeV) Ideally: include all channels  extend chiral MB-MB lagrangian to SU(4) However, c quark is very heavy mc ~1.4 GeV !

  31. V universal vector coupling constant J.Hofmann and M.F.M.Lutz, Nucl. Phys. A763, 90 (2005) t-channel exchange of vector mesons: • SU(4) at the vertices: • chiral symmetry in the light sector imposed  • SU(4) symmetry broken by the use of physical masses. In particular:

  32. DN DN DN amplitudes I=0 I=1 (dimensional regularization)

  33. contains: In-medium amplitude M.F.M.Lutz, and C.L.Korpa, Phys. Lett. B 633,43 (2006) • Pauli blocking on intermediate nucleons • Self-consistent dressing of D-meson cannot be regularized via DR  use a cut-off L But, the in medium  free amplitude T must be also determined with a cut-off L!

  34. T. Mizutani, A. Ramos, Phys. Rev. C74, 065201 (2006) • We obtain T with a loop function regularized with a cut-off L [adjusted to reproduce Lc(2593)] • We include an additional scalar-isoscalar interaction (S term) (from QCDSR) Model A: Model B:

  35. DN amplitudes (with cut-off regularization) I=0 I=1 R. Mizuk et al. [Belle Collaboration] Phys.Rev.Lett.94, 122002(2005) Sc(2800), G~60 MeV

  36. D-meson self-energy and spectral density (r=r0 and 2r0) r=r0 quasiparticle peak r=2r0 L. Tolos, A. Ramos and T. Mizutani, in preparation

  37. In the heavy sector, we have studied the DN interaction in coupled channels from a model inspired • on the work of Hofmann and Lutz, with some modifications: • a supplementary scalar-isoscalar interaction is introduced • momentum cut-off regularization more consistent than DR in view of its application to meson-baryon scattering in the medium The model generates the Lc(2595) in I=0, together with another resonance with I=1consistent with the observed Sc(2800) Conclusions Combining chiral dynamics with a non-perturbative unitarization technique, one can extend the range of applicability of the chiral lagrangian to study resonances. In the light sector, the L(1405) provides an excellent example of a dynamically generated resonance. There are two I=0 poles building up the nominal L(1405). These two resonances couple differently to pS and KN states and, as a consequence, the “properties” of the L(1405) (mass and width) will depend on the particular reaction employed to produce it.

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