Diapositiva 1

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HADRONIC PHYSICS IN SPAIN
NUPECC meeting Madrid (Spain), March 7, 2008
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Topics Chiral Perturbation TheoryQCD Sum
RulesEffective Field TheoryExotic
HadronsHadron Properties from LatticeExperimenta
l 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
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Define Hadronic physics, 1 o 2 slides
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Theory
Experiment
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We fit our 12 free parameters to 370 data points
and their reproduction from pp 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, pp
I 0 S-wave phase shifts d0 0, the
elasticity parameter ?0 0 S11, the I 0
S-wave pp ? K K phase shifts d1,2, S1,2, the
S-wave contribution to the pp ? ?? event
distribution and the event distribution for pp ?
??'. The last two panels corresponds to the phase
(f) and modulus (A) of the K-p ? K-p amplitude
from the LASS data. Compared with other works we
determine the interaction kernels from standard
chiral Lagrangians, avoiding ad-hoc
parameterizations.
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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.
  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  
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Excited Glue(Glueballs and Hybrids)
Charm in Nuclei
Charmonium
Hypernuclei
D- and DS-Physics
Other Topics
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SPAIN, MADRID, CIEMAT TLCP Pedro LADRON DE
GUEVARA SPAIN, SANTIAGO DE COMPOSTELA,
UNIVERSIDAD DE SANTIAGO DE COMPOSTELA TLCP
Carlos PAJARES
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

                
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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 ?-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 (?, ?, O). mesons
containing charm or anti-charm quarks (D, J/?).
collective flow of all observed particles.
event-by-event fluctuations.
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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
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Outline
Chiral unitary model
The L(1405) and its two-pole nature
Other sectors eg S-2 X resonances
Heavy flavored baryon resonances
18

• 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!

19
Chiral Unitary Model

1. 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
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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)
21
K-p low energy scattering properties and the
L(1405)
L adjusted to reproduce branching ratios
L630 MeV (f1.15fp)

• 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
22
Elastic and inelastic cross sections
p-waves also included (D.Jido, E.Oset, A.Ramos,
PRC66 (2002) 055203)
Total cross sections

L,S,S
Differential cross sections
23

• 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
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The two-pole structure of the L(1405)
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 8 X 8 1 8s 8a 10 10
27 meson X baryon
In the SU(3) basis

• Taking common baryon and meson masses (MiM0,
  mim0) in both Vij and Gl
• one obtains a SU(3) symmetric Tij
• ? a singlet (1) and two degenerate octets (8s,8a)
  of Jp1/2- bound states appear!

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Breaking SU(3) gradually Mi(x) M0 x
(Mi-M0) up to the physical masses m2i(x) m20
x (m2i-m20) x0.(0.1)1 ai(x) a0 x
(ai-a0)
M0 1151 MeV m0 368 MeV a0 -2.148
S-1 sector
s
In I0, the evolved octet and the evolved singlet
appear very nearby ? The nominal L(1405) is the
reflection of two poles of the T-matrix !
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S-1 poles and couplings to physical states with
I0
zR 1390 - 66i 1426 - 16i 1680 - 20i
(I0) gi gi gi
pS 2.9 1.5 0.27
KN 2.1 2.7 0.77
hL 0.77 1.4 1.1
KX 0.61 0.35 3.6
The properties of the L(1405) will depend on
which amplitude initiates the reaction!
T2pcm
TKN ?pS selects preferentially the higher energy
(narrower) pole
TpS?pS selects preferentially the lower
energy (wider) pole
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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)
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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
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Other sectors
JP1/2-
S0 ? 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
JP3/2-
? 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
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S-2
Experimental situation p-wave X(1530) I1
/2 JP3/2 s-wave X(1620),
X(1690) I1/2 JP not measured
X(1620) G 20 50 MeV (into pX states)
(seen recently at CLAS in
the g p ? p- K K- (Xp) reaction) X(1690) G
10 50 MeV (into KS, KL, pX 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 pX, KL, KS, hX
A. Ramos, E. Oset, C. Bennhold, Phys. Rev. Lett.
89 (2002) 252001
zR 1605 - 65i
(I1/2) gi
pX 2.4
KL 2.6
KS 0.96
hX 0.48
Taking apX-3.1 aKL-1.0 aKS-2.0 ahX-2.0

• We identify this resonance
• with the X(1620)
• JP1/2- can be assigned!

(of natural size)
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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)

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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 the Lc(2593) dynamically from DN
  dynamics?

• The DN interaction is intimately connected to
  the properties of the
• D-meson in a nuclear medium

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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)
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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
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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
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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)
37
Earlier attempts of coupled-channel calculations
of the DN amplitude
L. Tolós, J. Schaffner-Bielich, and A.
Mishra, Phys. Rev.C 70, 025203 (2004) (T0
MeV) L. Tolós, J. Schaffner-Bielich, and H.
Stöcker, Phys. Lett. B635, 85 (2006) (finite T)
Channels for C1, S0

• 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 no DN, DsY
channels ?I0, C1 resonance found at 2650 MeV
that couples strongly to pSc (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 !
38
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

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DN amplitudes
I0
I1
(dimensional regularization)
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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!
41
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
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DN amplitudes (with cut-off regularization)
I0
I1
R. Mizuk et al. Belle Collaboration Phys.Rev.Let
t.94, 122002(2005) Sc(2800), G60 MeV
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D-meson self-energy and spectral density (rr0
and 2r0)
rr0
quasiparticle peak
r2r0
L. Tolos, A. Ramos and T. Mizutani, in preparation
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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 I0 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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J/Y suppression from decay to DDbar unlikely!
Production of J/Y would be reduced due to decay
of the feeding c states into channels that
become accessible in the medium