Presentation on theme: "HADRONIC PHYSICS IN SPAIN NUPECC meeting Madrid (Spain), March 7, 2008."— Presentation transcript:
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 Spectroscopy of light and heavy quark mesons Baryons Quarkonia Glueballs, hybrids and multiquarks Phenomenological models Effective lagrangians QCD on the lattice Hadrons in matter Heavy ion collisions Future facilities
Define Hadronic physics, 1 o 2 slides
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 Kπ+ Kπ+ amplitude from the LASS data. Compared with other works we determine the interaction kernels from standard chiral Lagrangians, avoiding ad-hoc parameterizations.
Departamento de Física de Partículas, University of Santiago de Compostela, Santiago de Compostela, Spain D. Belver P. Cabanelas E. Castro J. A. Garzón Departamento de Física de Partículas, University of Santiago de Compostela Instituto de Física Corpuscular, Universidad de Valencia-CSIC, Valencia, Spain J. Díaz A. Gil Instituto de Física Corpuscular, Universidad de Valencia-CSIC 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 spectrometer HADES was set up, and is in operation, at GSI by an international collaboration of 17 institutions from 9 European countries.electron-positron pair spectrometerGSI international collaboration
Excited Glue (Glueballs and Hybrids) Charm in Nuclei Charmonium Hypernuclei D- and D S -Physics Other Topics
The ALICE Collaboration is building a dedicated heavy-ion detector to exploit the unique physics potential of nucleus-nucleus interactions at LHC energies. Our aim is to study the physics of strongly interacting matter at extreme energy densities, where the formation of a new phase of matter, the quark-gluon plasma, is expected. The existence of such a phase and its properties are key issues in QCD for the understanding of confinement and of chiral- symmetry restoration. For this purpose, we intend to carry out a comprehensive study of the hadrons, electrons, muons and photons produced in the collision of heavy nuclei. Alice will also study proton-proton collisions both as a comparison with lead-lead collisions in physics areas where Alice is competitive with other LHC experiments SPAIN, MADRID, CIEMAT; TL&CP: Pedro LADRON DE GUEVARACIEMAT SPAIN, SANTIAGO DE COMPOSTELA, UNIVERSIDAD DE SANTIAGO DE COMPOSTELA; TL&CP: Carlos PAJARESUNIVERSIDAD DE SANTIAGO DE COMPOSTELA
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.
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
Chiral unitary model The (1405) and its two-pole nature Other sectors: eg S=-2 resonances Heavy flavored baryon resonances Outline:
K N scattering: a lively topic K N scattering in the I=0 channel is dominated by the presence of the (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 (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 PT not applicable non-perturbative techniques implementing unitarization in coupled channels are mandatory!
1.Build a transition potential V from the meson-baryon Lagrangian at lowest order 2. Unitarization: N/D method equivalent to Bethe-Salpeter coupled-channel equations with on-shell amplitudes MjMj BjBj BiBi V ij = MiMi s-wave M B coupled channels for S=-1: Pioneer work: N.Kaiser,P.B.Siegel,W.Weise, Nucl.Phys.A594 (1995) 325 omitted next-to-leading order: L 2 K KN (MeV) Chiral Unitary Model: T ij = V ij + V il G l T lj = +
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 ~ 1 GeV)
K - p low energy scattering properties and the (1405) adjusted to reproduce branching ratios: E. Oset and A. Ramos, NPA635 (1998) 99 Invariant mass distribution Y channels are necessary to: obtain a good description of the threshold branching ratios (especially ) preserve SU(3) symmetry (1.04 without ) =630 MeV (f=1.15f )
Elastic and inelastic cross sections p-waves also included (D.Jido, E.Oset, A.Ramos, PRC66 (2002) ) + Total cross sections Differential cross sections
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) M.F.M. Lutz, E.E. Kolomeitsev, Nucl. Phys. A700 (2002) 193 more channels, next-to-leading order, Born terms beyond WT (s-channel, u-channel), Fits including new data … B.Borasoy, R. Nissler, and W. Weise, Phys. Rev. Lett. 94, (2005); Eur. Phys. J. A25, 79 (2005) J.A. Oller, J. Prades, and M. Verbeni, Phys. Rev. Lett. 95, (2005) J. A.Oller, Eur. Phys. J. A28, 63 (2006) B. Borasoy, U. G. Meissner and R. Nissler, Phys. Rev. C74, (2006).
The two-pole structure of the (1405) The meson-baryon states built from the 0 - pseudoscalar meson octet and the 1/2 + baryon octet can be classified into SU(3) multiplets: 8 X 8 = 1 + 8s + 8a meson X baryon In the SU(3) basis: attractive Taking common baryon and meson masses (M i ~M 0, m i ~m 0 ) in both V ij and G l one obtains a SU(3) symmetric T ij a singlet (1) and two degenerate octets (8s,8a) of J p =1/2 - bound states appear! 1 8 a 8 s 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
Breaking SU(3) gradually M i (x) = M 0 + x (M i -M 0 ) up to the physical masses: m 2 i (x) = m x (m 2 i -m 2 0 ) x=0.(0.1)1a i (x) = a 0 + x (a i -a 0 ) M 0 = 1151 MeV m 0 = 368 MeV a 0 = S=-1 sector In I=0, the evolved octet and the evolved singlet appear very nearby: The nominal (1405) is the reflection of two poles of the T-matrix ! s
|T| 2 p cm T selects preferentially the lower energy (wider) pole T KN selects preferentially the higher energy (narrower) pole The properties of the (1405) will depend on which amplitude initiates the reaction! z R i i i (I=0) |g i | S=-1 poles and couplings to physical states with I=0
Experimental evidence - p K 0 D.W.Thomas et al. Nucl. Phys. B56, 15 (1973) K - p S. Prakhov et al., Phys.Rev. C70, (2004)
confirmed by models! where: T.Hyodo, et al, Phys. Rev. C68 (2003) p K 0 The N*(1710) mechanism stresses the role of T The chiral terms stress the role of T KN V. K. Magas, E. Oset and A. Ramos, Phys. Rev. Lett. 95, (2005) K - p M I ~ 1420 MeV dominated by the amplitude T KN
Other sectors J P =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) J. Nieves and E. Ruiz Arriola, Phys. Rev. D64 (2001) M.F.M. Lutz, E.E. Kolomeitsev, Nucl. Phys. A730 (2004) 110 … S=-2 (1620), (1690) A. Ramos, E. Oset, C. Bennhold, Phys. Rev. Lett. 89 (2002) C. Garcia-Recio, J.Nieves, M.Lutz, Phys. Lett. B582 (2004) 49 J P =3/2 - (Interaction of the 0- meson octet with the 3/2+ baryon decuplet) (1700), (1520), (1670), (1820) E.E. Kolomeitsev, M.F.M. Lutz, Phys. Lett. B585 (2004) 243 S. Sarkar, E. Oset, M.J. Vicente-Vacas, Phys. Rev. C72 (2005) L. Roca, S. Sarkar, V.K. Magas and E. Oset, Phys. Rev. C73 (2006) M. Döring, E. Oset, D. Strottman, Phys. Rev. C73 (2006) M. Döring, E. Oset, D. Strottman, Phys. Lett. B639 (2006) 59
Experimental situation: p-wave: (1530)****I=1/2 J P =3/2 + s-wave: (1620)*, (1690)***I=1/2J P : not measured (1620) = 20 – 50 MeV (into states) (seen recently at CLAS in the p - K + K - ( ) reaction) (1690) = 10 – 50 MeV (into states) 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: z R i (I=1/2) |g i | Taking: a =-3.1 a =-1.0 a =-2.0 We identify this resonance with the (1620)* J P =1/2 - can be assigned! A. Ramos, E. Oset, C. Bennhold, Phys. Rev. Lett. 89 (2002) S=-2 (of natural size)
invariant mass distribution threshold: 1611 MeV ~50 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)
Heavy flavoured baryon resonances In the charm sector we find a resonance. the c (2593) (udc), that bears a strong ressemblance to the (1405) (uds) in KN dynamics Can we generate the c (2593) dynamically from DN dynamics? The DN interaction is intimately connected to the properties of the D-meson in a nuclear medium
It is produced in pairs (D +,D - ) in heavy ion experiments: or antiproton anhilation experiments (PANDA at FAIR) on protons and nuclei: Understanding the interaction of charmed mesons in a hadronic medium is an important issue: 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/ supression (attributed to be a signal for the formation of a Quark-Gluon Plasma)
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 (m c ) 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
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 ( ) and vector ( ) density-dependent meson fields A.Mishra, E.L. Brakovskaya, J. Schaffner-Bielich, S. Schramm, and H. Stoecker, Phys. Rev. C 70, (2004) Variety of results, depending on ingredients of the model and its parameters:
Quark Meson Coupling approach Hadron interactions mediated by the exchange of scalar-isoscalar ( and vector ( and ) 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 c (2593) (udc)
L. Tolós, J. Schaffner-Bielich, and A. Mishra, Phys. Rev.C 70, (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 M.F.M.Lutz and E.E.Kolomeitsev, Nucl. Phys. A730, 110 (2004) Earlier attempts of coupled-channel calculations of the DN amplitude Exploits the similarity between (1495) and c (2593): s replaced by c in a SU(3) chiral invariant model (only channels with non-strange hadrons) The c (2593) is generated as a DN s-wave molecular state having a width of 3 MeV Scattering of Goldstone bosons (,K, ) off ground state charmed baryons ( c, c …). Proper symmetries respected but no DN, D s Y channels I=0, C=1 resonance found at 2650 MeV that couples strongly to c (very large width ~ 80 MeV) Ideally: include all channels extend chiral MB-MB lagrangian to SU(4) However, c quark is very heavy m c ~1.4 GeV !
J.Hofmann and M.F.M.Lutz, Nucl. Phys. A763, 90 (2005) t-channel exchange of vector mesons: V universal vector coupling constant SU(4) at the vertices: chiral symmetry in the light sector imposed SU(4) symmetry broken by the use of physical masses. In particular:
In-medium amplitude contains: Self-consistent dressing of D-meson Pauli blocking on intermediate nucleons M.F.M.Lutz, and C.L.Korpa, Phys. Lett. B 633,43 (2006) cannot be regularized via DR use a cut-off But, the in medium free amplitude T must be also determined with a cut-off
We obtain T with a loop function regularized with a cut-off [adjusted to reproduce c (2593)] T. Mizutani, A. Ramos, Phys. Rev. C74, (2006) We include an additional scalar-isoscalar interaction ( term) (from QCDSR) Model A: Model B:
I=0I=1 DN amplitudes (with cut-off regularization) R. Mizuk et al. [Belle Collaboration] Phys.Rev.Lett.94, (2005) c (2800), ~60 MeV
D-meson self-energy and spectral density and 2 L. Tolos, A. Ramos and T. Mizutani, in preparation quasiparticle peak
Conclusions 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 c (2595) in I=0, together with another resonance with I=1consistent with the observed c (2800) 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 1405 provides an excellent example of a dynamically generated resonance. There are two I=0 poles building up the nominal 1405 These two resonances couple differently to and states and, as a consequence, the properties of the 1405 (mass and width) will depend on the particular reaction employed to produce it.
J/ suppression from decay to DDbar unlikely! Production of J/ would be reduced due to decay of the feeding states into channels that become accessible in the medium