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ABSTRACT: We study the process $J/\Psi \to \gamma \phi \omega$, measured by the BES
experiment, where a neat peak close to the $\phi \omega$ threshold is observed
and is associated to a scalar meson resonance around 1800 MeV. We make the
observation that a scalar resonance coupling to $\phi \omega$ unavoidably
couples strongly to $K \bar K$, but no trace of a peak is seen in the $K \bar
K$ spectrum of the $J/\Psi \to \gamma K \bar K$. This, reinforced by the
negative results from a devoted Belle experiment in a related reaction, serves
us to rule out the interpretation of the observed peak as a signal of a new
resonance. After this is done, a thorough study is done on the production of a
pair of vector mesons and how its unavoidable interaction leads necessarily to
a peak in the $J/\Psi \to \gamma \phi \omega$ reaction close to the $\phi
\omega$ threshold, due to the dynamical generation of the $f_0(1710)$ resonance
by the vector-vector interaction. We then show that both the shape obtained for
the $\phi \omega$ mass distribution, as well as the strength are naturally
reproduced by this mechanism.
10/2012;
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ABSTRACT: A $D$-like meson resonance with mass around 2.9 GeV has been found in the
$DK\bar K$ system using two independent and different model calculations based
on: (1) QCD sum rules and (2) solution of Fadeev equations with input
interactions obtained from effective field theories built by considering both
chiral and heavy quark symmetries. The QCD sum rules have been used to study
the $D_{s^*0}(2317) \bar{K}$ and $D f_0(980)$ molecular currents. A resonance
of mass 2.926 GeV is found with the $D f_0(980)$ current. Although a state in
the $D_{s^*0}(2317) \bar{K}$ current is also obtained, with mass around 2.9
GeV, the coupling of this state is found to be two times weaker than the one
formed in $D f_0(980)$. On the other hand, few-body equations are solved for
the $D K \bar{K}$ system and its coupled channels with the input $t$-matrices
obtained by solving Bethe-Salpeter equations for the $D K$, $D\bar{K}$ and $K
\bar{K}$ subsystems. In this study a $D$-like meson with mass 2.890 GeV and
full width $\sim$ 55 MeV is found to get dynamically generated when $D K
\bar{K}$ gets reorganized as $D f_0(980)$. However, no clear signal appears for
the $D_{s^*0}(2317) \bar{K}$ configuration. The striking similarity between the
results obtained in the two different models indicates strongly towards the
existence of a $D f_0 (980)$ molecule with mass nearly 2.9 GeV.
09/2012;
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ABSTRACT: The magnetic moments of the low-lying spin-parity $J^P=$ $1/2^-$, $3/2^-$
$\Lambda$ resonances, like, for example, $\Lambda(1405)$ $1/2^-$,
$\Lambda(1520)$ $3/2^-$, as well as their transition magnetic moments, are
calculated using the chiral quark model. The results found are compared with
those obtained from the nonrelativistic quark model and those of unitary chiral
theories, where some of these states are generated through the dynamics of two
hadron coupled channels and their unitarization.
08/2012;
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ABSTRACT: The magnetic moments of the negative parity octet resonances with spin {1/2}:
$N^*$(1535), $N^*$(1650), $\Sigma^*$(1620), and $\Xi^*$(1690) have been
calculated within the framework of the chiral constituent quark model. In this
approach, the presence of the polarized $q\bar{q}$ pairs (or the meson cloud,
in other words) is considered by using the Lagrangian for Goldstone boson
emission from the constituent quarks. Further, the explicit contributions
coming from the spin and orbital angular momentum, including the effects of the
configurations mixing between the states with different spins, are obtained.
The motivation for these calculations comes from the recent interest in
experimental measurement of the magnetic moment of the ${S_{11}(1535)}$
resonance and of similar calculations being done within lattice quantum
chromodynamics approaches. Our results can be compared with those expected to
come from these sources.
07/2012;
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ABSTRACT: An exploration of the dynamically generated $\Lambda$ and $\Sigma$ resonances
has been made in the vector meson-baryon (VB) systems coupled to pseudoscalar
meson-baryon (PB) channels. The VB interactions are obtained from the
Lagrangians written within the hidden local symmetry which, in addition to
Yukawa-type vector-baryon-baryon (VBB) vertices, naturally gives rise to a
contact interaction. Using the VBB vertices, we calculate the $t$-, $s$- and
$u$-channel diagrams considering the octet baryon exchange in the latter two
cases. For the PB channels we rely on the the Weingberg-Tomozawa interactions
and calculate the PB $\leftrightarrow$ VB transition amplitudes extending the
Kroll-Ruderman theorem by replacing the photon by the vector mesons. In
addition to the low-lying $\Lambda(1405)$, $\Lambda(1670)$ found in previous
works, we find resonances which coincide well with: $\Lambda(2000)$,
$\Sigma(1750) S_{11}$, $\Sigma(1940) D_{13}$, $\Sigma(2000) S_{11}$ and predict
three $\Lambda^*$'s with $J^\pi = 3/2^-$ and masses: $1754 - i2$ MeV, $1862 -
i33$ MeV, $2139 - i14$ MeV together with a broad $1/2^-$ $\Sigma^*$ with mass
$\sim$ 1430 MeV. We find that most of these next-to-low-lying states couple
weakly with the pseudoscalar mesons, which implies that it is important to
study the reactions with VB final states in order to obtain a reliable
information on the properties of such resonances.
03/2012;
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ABSTRACT: We review recent work concerning the $\bar{K}N$ interaction and Faddeev
equations with chiral dynamics which allow us to look at the $\bar{K}NN$ from a
different perspective and pay attention to problems that have been posed in
previous studies on the subject. We show results which provide extra
experimental evidence on the existence of two $\Lambda(1405)$ states. We then
show the findings of a recent approach to Faddeev equations using chiral
unitary dynamics, where an explicit cancellation of the two body off shell
amplitude with three body forces stemming from the same chiral Lagrangians
takes place. This removal of the unphysical off shell part of the amplitudes is
most welcome and renders the approach unambiguous, showing that only on shell
two body amplitudes need to be used. With this information in mind we use an
approximation to the Faddeev equations within the fixed center approximation to
study the $\bar{K}NN$ system, providing answers within this approximation to
questions that have been brought before and evaluating binding energies and
widths of this three body system. As a novelty with respect to recent work on
the topic we find a bound state of the system with spin S=1, like a bound state
of $\bar{K}$-deuteron, less bound that the one of S=0, where all recent efforts
have been devoted. The width is relatively large in this case, suggesting
problems in a possible experimental observation.
03/2012;
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ABSTRACT: In this manuscript, I will report the details of our recent work on the
vector meson-baryon (VB) interaction, which we studied with the motivation of
finding dynamical generation of resonances in the corresponding systems. We
started our study by building a formalism based on the hidden local symmetry
and calculating the leading order contributions to the scattering equations by
summing the diagrams with: (a) a vector meson exchange in the t-channel (b) an
octet baryon exchange in the s-, u-channels and (c) a contact interaction
arising from the part of the vector meson-baryon Lagrangian which is related to
the anomalous magnetic moment of the baryons. We find the contribution from all
these sources, except the s-channel, to be important. The amplitudes obtained
by solving the coupled channel Bethe-Salpeter equations for the systems with
total strangeness zero, show generation of one isospin 3/2, spin 1/2 resonance
and three isospin 1/2 resonances: two with spin 3/2 and one with spin 1/2. We
identify these resonances with $\Delta$ (1900) $S_{31}$, $N^*$(2080) $D_{13}$,
$N^*$(1700) $D_{13}$, and $N^*$(2090) $S_{11}$, respectively.
We have further extended our study by including pseudoscalar meson-baryon
(PB) as the coupled channels of VB systems. For this, we obtain the PB
$\rightarrow$ VB amplitudes by using the Kroll-Ruddermann term where,
considering the vector meson dominance phenomena, the photon is replaced by a
vector meson. The calculations done within this formalism reveal a very strong
coupling of the VB channels to the low-lying resonances like $\Lambda$(1405)
and $\Lambda$(1670), which can have important implications on certain reactions
producing them. In addition to this, we find that the effect of coupling the
higher mass states to the lighter channels is not restricted to increasing the
width of those states, it can be far more strong.
02/2012;
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ABSTRACT: In this talk we show recent developments on few body systems involving
mesons.
We report on an approach to Faddeev equations using chiral unitary dynamics,
where an explicit cancellation of the two body off shell amplitude with three
body forces stemming from the same chiral Lagrangians takes place. This removal
of the unphysical off shell part of the amplitudes is most welcome and renders
the approach unambiguous, showing that only on shell two body amplitudes need
to be used. Within this approach, systems of two mesons and one baryon are
studied, reproducing properties of the low lying $1/2^+$ states. On the other
hand we also report on multirho and $K^*$ multirho states which can be
associated to known meson resonances of high spin.
10/2011;
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ABSTRACT: A study of meson-baryon systems with total strangeness -1 is made within a
framework based on the chiral and hidden local symmetries. These systems
consist of octet baryons, pseudoscalar and vector mesons. The pseudoscalar
meson-baryon (PB) dynamics has been earlier found determinant for the existence
of some strangeness -1 resonances, for example, $\Lambda(1405)$,
$\Lambda(1670)$, etc. The motivation of the present work is to study the effect
of coupling the closed vector meson-baryon (VB) channels to these resonances.
To do this, we obtain the $PB \rightarrow PB$ and $VB \rightarrow VB$
amplitudes from the t-channel diagrams and the $PB \leftrightarrow VB$
amplitudes are calculated using the Kroll-Ruddermann term where, considering
the vector meson dominance phenomena, the photon is replaced by a vector meson.
The calculations done within this formalism reveal a very strong coupling of
the VB channels to the $\Lambda(1405)$ and $\Lambda(1670)$. In the isospin 1
case, we find an evidence for a double pole structure of the $\Sigma (1480)$
which, like the isospin 0 resonances, is also found to couple strongly to the
VB channels. The strong coupling of these low-lying resonances to the VB
channels can have important implications on certain reactions producing them.
07/2011;
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ABSTRACT: A study of three-pseudoscalar $\pi K \bar{K}$ and $\pi \pi \eta$ coupled
system is made by solving the Faddeev equations within an approach based on
unitary chiral dynamics. A resonance with total isospin one and spin-parity
$J^\pi = 0^-$ is found with mass $\sim$ 1400 MeV when the $K \bar{K}$ system
gets reorganized as the $f_0(980)$. This resonance is identified with the $\pi
(1300)$ listed by the Particle Data Group. Further, the two-body amplitude
which describes the interaction between a $\pi$ and the $f_0(980)$ is extracted
from the study of the $\pi K\bar K$ and $\pi\pi\eta$ system and is then
employed to study the $f_0(980)\pi \pi $ system. As a result, a scalar
resonance is found near 1790 MeV which drives the two $ f_0 (980)\pi$ systems
to resonate as the $\pi (1300)$ while the invariant mass of the two pions falls
in the mass region of the scalar $\sigma (600)$. These findings support the
existence of a new $f_0$ resonance near 1790 MeV, as found by the BES and
Crystal Barrel collaborations. Our results show that this $f_0(1790)$ is
definitely distinct to $f_0(1710)$, the latter of which seems to possess a
glueball structure dominantly.
06/2011;
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ABSTRACT: The purpose of this work is to study vector meson-octet baryon interactions
with the aim to find dynamical generation of resonances in such systems. For
this, we consider s-, t-, u-channel diagrams along with a contact interaction
originating from the hidden local symmetry Lagrangian. We find the contribution
from all these sources, except the s-channel, to be important. The amplitudes
obtained by solving coupled channel Bethe Salpeter equations for systems with
total strangeness zero, show generation of one isospin 3/2, spin 1/2 resonance
and three isospin 1/2 resonances: two with spin 3/2 and one with spin 1/2. We
identify these resonances with $\Delta (1900) S_{31}$, $N^* (2080) D_{13}$,
$N^* (1700) D_{13}$, and $N^*(2090) S_{11}$, respectively.
04/2011;
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ABSTRACT: Our study of meson-meson-baryon systems with total strangeness zero revealed that many nucleon resonances can be understood as dynamically generated states of three-hadrons. We considered ππN,πηN,πKΛ, and πKΣ as coupled channels and solved the Fadeev equations. To be precise, the study lead to dynamical generation of N*(1710), N*(2100), Δ(1910) along with a new isospin 1/2 resonance around 1920 MeV. In this manuscript I briefly review the formalism we use for three-body calculations and the results obtained for the nucleon resonances.
AIP Conference Proceedings. 12/2010; 1322(1):379-383.
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ABSTRACT: We report on four $\Sigma$'s and three $\Lambda$'s, in the 1500 - 1800 MeV
region, as two meson - one baryon S-wave $(1/2)^+$ resonances found by solving
the Faddeev equations in the coupled channel approach, which can be associated
to the existing $S$ = -1, $J^P= 1/2^+$ low lying baryon resonances. On the
other hand we also report on a new, hidden strangeness $N^*$ state, mostly made
of $K \bar{K} N$, with mass around 1920 MeV, which we think could be
responsible for the peak seen in the $\gamma p \to K^+ \Lambda$ around this
energy. Finally we address a very novel topic in which we show how few body
systems of several $\rho$ mesons can be produced, with their spins aligned up
to J=6, and how these states found theoretically can be associated to several
known mesons with spins J=2,3,4,5,6.
10/2010;
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ABSTRACT: In this talk, I discuss our recent studies of three-hadron systems and the resonances found therein. The studies consist of solving Faddeev equations with the input two body interactions obtained from the chiral Lagrangians. The systems which we study are either made of two mesons and a baryon or of three mesons. The motivation for these studies comes from the data on many baryon resonances, especially the ones with Jπ = 1/2+, which show a large branching ratio to the two meson-one baryon decay channels. In addition to this, several new studies at BES, BELLE, BABAR etc., claim the existence of new meson resonances which seem to couple strongly to three-meson systems, where mostly two out of the three mesons appear as a known resonance. Hitherto, we have studied two meson-one baryon systems with strangeness = −1, 0 and 1 and three-meson systems made of two-pseudoscalars and a vector meson. As we will show in this manuscript, we find many resonances which couple to three-hadrons.
Chinese Physics C 09/2010; 34(9):1286. · 0.27 Impact Factor
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ABSTRACT: In this manuscript we discuss about our study of the $N pi ar{K}$ and the NπK systems made by solving the Faddeev equations with the two-body t-matrices obtained by solving the Bethe-Salpeter equations with the potentials obtained from chiral dynamics. In the strangeness = -1 case, we found that all the Λ and Σ resonances listed by the particle data group, with spin-parity 1/2+ , in the 1550-1800 MeV region get generated due to the involved three-body dynamics. This motivated us to study the strangeness =1 three-body system, i.e., NπK , where we did not find any evidence for the Θ+ (1542) but found a broad bump around 1700 MeV which has a κ(800)N structure.
EPJ Web of Conferences. 01/2010;
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ABSTRACT: We have solved the Faddeev equations for the ππN system and coupled channels resulting into the dynamical generation of two N* , N* (1710) and N* (2100), and one ∆ states, ∆ (1910), all of them with J P = 1/2+ . In addition, signatures for a new N* resonance with JP = 1/2+ are found around at an energy of 1920 MeV.
EPJ Web of Conferences. 01/2010;
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ABSTRACT: In this talk I make a review on the theoretical and experimental situation around the deeply bound kaon clusters, the possible bound kaonic states of nuclear, rather than atomic nature. At the same time I discuss novel developments around other kind of bound kaon clusters, which include states of two mesons and one baryon, with either one or two kaons, and states of a vector meson and two kaons, which explain naturally the observed properties of the X(2175) and Y(4260) resonances. Comment: 17 pages. Talk at the Few Body Conference, Bonn, September 2009
12/2009;
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ABSTRACT: A study of the J/ψππ and J/ψKK̅ systems, treating them as coupled channels, has been made by solving the Faddeev equations, with the purpose of investigating the possibility of generation of the JPC=1--, Y(4260) resonance due to the interaction between these three mesons. In order to do this, we start by solving the Bethe-Salpeter equation for the two pseudoscalar and for the vector-pseudocalar meson systems using the amplitudes obtained from the lowest order chiral Lagrangians as potentials. With the t- matrices generated from these potentials, which contain the poles of the σ, f0(980), and a0(980) resonances for the pseudoscalar-pseudoscalar system and the pole of the X(3872), along with other new charmed resonant states, for the vector-pseudoscalar system, we solve the Faddeev equations. As a result, we get a peak around 4150 MeV with a width ∼90 MeV when the invariant mass of the two pseudoscalars is close to that of the f0(980).
Phys. Rev. D. 11/2009; 80(9).
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ABSTRACT: A study of the $J/\psi \pi \pi$ and $J/\psi K \bar{K}$ systems, treating them as coupled channels, has been made by solving the Faddeev equations, with the purpose of investigating the possibility of generation of the $J^{PC} = 1^{--}$, Y(4260) resonance due to the interaction between these three mesons. In order to do this, we start by solving the Bethe-Salpeter equation for the two pseudoscalar and for the vector-pseudocalar meson systems using the amplitudes obtained from the lowest order chiral Lagrangians as potentials. With the $t$-matrices generated from these potentials, which contain the poles of the $\sigma$, $f_{0}(980)$ and $a_{0}(980)$ resonances for the pseudoscalar-pseudoscalar system and the pole of the X(3872), alongwith other new charmed resonant states, for the vector-pseudoscalar system, we solve the Faddeev equations. As a result, we get a peak around 4150 MeV with a width $\sim$ 90 MeV when the invariant mass of the two pseudoscalars is close to that of the $f_0 (980)$. Comment: Published version; some typo corrected
06/2009;
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ABSTRACT: We study the $N \pi K$ system in order to investigate the possibility of existence of strangeness +1 resonance(s). The formalism consists of solving the Faddeev equations with the $N \pi$, $\pi K $ and $K N$ $t$-matrices obtained from chiral dynamics. The same formalism, which leads to the finding of several $1/2^+$ resonances in the corresponding three-body $S$ = -1 channels in the 1400-2000 MeV energy region, results into only one broad bump around 1700 MeV with isospin 0. The amplitudes in isospin 1 and 2 configuration do not have any resonant structure.
02/2009;
