0000000000893453
AUTHOR
Alberto Martínez Torres
Solution to Faddeev equations with two-body experimental amplitudes as input and application to J^P=1/2^+, S=0 baryon resonances
We solve the Faddeev equations for the two meson-one baryon system pi pi N and coupled channels using the experimental two-body t matrices for the pi N interaction as input and unitary chiral dynamics to describe the interaction between the rest of coupled channels. In addition to the N-*(1710) obtained before with the pi pi N channel, we obtain, for J(pi)=1/2(+) and total isospin of the three-body system I=1/2, a resonance peak whose mass is around 2080 MeV and width 54 MeV, while for I=3/2 we find a peak around 2126 with 42 MeV of width. These two resonances can be identified with the N-*(2100) and the Delta(1910), respectively. We obtain another peak in the isospin 1/2 configuration, aro…
Y(4260) as a J/Sigma KK system
A study of the J/ψππ and J/ψKK¯ 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), alongwith oth…
KD, eta Ds interaction in finite volume and the Ds*0(2317) resonance
An SU(4) extrapolation of the chiral unitary theory in coupled channels done to study the scalar mesons in the charm sector is extended to produce results in finite volume. The theory in the infinite volume produces dynamically the $D_{s^*0}(2317)$ resonance by means of the coupled channels $KD$, $\eta D_s$. Energy levels in the finite box are evaluated and, assuming that they would correspond to lattice results, the inverse problem of determining the bound states and phase shifts in the infinite volume from the lattice data is addressed. We observe that it is possible to obtain accurate $KD$ phase shifts and the position of the $D_{s^*0}(2317)$ state, but it requires the explicit considera…
Reanalysis of lattice QCD spectra leading to the Ds0*(2317) and Ds1*(2460)
We perform a reanalysis of the energy levels obtained in a recent lattice QCD simulation, from where the existence of bound states of KD and KD* are induced and identified with the narrow D-s0*(2317) and D-s1*(2460) resonances. The reanalysis is done in terms of an auxiliary potential, employing a single-channel basis KD(*()), and a two-channel basis KD(*()), eta D-s(()*()). By means of an extended Luscher method we determine poles of the continuum t-matrix, bound by about 40 MeV with respect to the KD and KD* thresholds, which we identify with the D-s0*(2317) and D-s1*(2460) resonances. Using a sum rule that reformulates Weinberg compositeness condition we can determine that the state D-s0…
Faddeev fixed-center approximation to the N K K(bar) system and the signature of a N*(1920)(1/2+) state
We perform a calculation for the three body NK¯K scattering amplitude by using the fixed center approximation to the Faddeev equations, taking the interaction between N and K¯, N and K, and K¯ and K from the chiral unitary approach. The resonant structures show up in the modulus squared of the three body scattering amplitude and suggest that a NK¯K hadron state can be formed. Our results are in agreement with others obtained in previous theoretical works, which claim a new N∗ resonance around 1920 MeV with spin-parity JP=1/2+. The existence of these previous works allows us to test the accuracy of the fixed center approximation in the present problem and sets the grounds for possible applic…
A new perspective on the Faddeev equations and the (K)over-bar N N system from chiral dynamics and unitarity in coupled channels
We review recent work concerning the K¯N interaction and Faddeev equations with chiral dynamics which allow us to look at the 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 Λ(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 unamb…
Reanalysis of the e(+)e(-) -> (D*(D*)over-bar)(+/-)pi(-/+) reaction and the claim for the Z(c)(4025) resonance
In this paper we study the reaction e(+)e(-) -> (D*(D*) over bar (+/-)pi(-/+) in which the BESIII collaboration has claimed the existence of a 1(+) resonance, named Z(c)(4025), in the (D*(D*) over bar invariant mass spectrum with a mass around 4026 MeV and width close to 26 MeV. We determine the (D*(D*) over bar invariant mass distribution and find that although the explanation considered by the BESIII collaboration is plausible, there are others which are equally possible, like a 2(+) resonance or a bound state. Even more, we find that the data can be explained without the existence of a resonance/bound state. In view of the different possible interpretations found for the BESIII data, we …
The gamma d -> K(+)K(-)np reaction and an alternative explanation for the "Theta(+)(1540) pentaquark" peak
We present a calculation of the gamma d -> K(+)K(-)np reaction with the aim of seeing whether the experimental peak observed in the K(+)n invariant mass around 1526 MeV, from where evidence for the existence of the Theta(+) has been claimed, can be obtained without this resonance as a consequence of the particular dynamics of the process and the cuts applied in the experimental setup. We find that a combination of facts leads indeed to a peak around 1530 MeV for the invariant mass of K(+)n without the need to invoke any new resonance around this energy. This, together with statistical fluctuations that we prove to be large with the statistics of the experiment, is likely to produce the narr…
The sigma K coupling in the chiral unitary approach and the isoscalar (K)over-barN , (K)over-barA interaction
We evaluate the 'σ' exchange contribution to the K¯N→K¯N scattering within a chiral unitary approach. We show that the chiral transition potentials for ππ→KK¯ in the t-channel lead to a 'σ' contribution that vanishes in the K¯ forward direction and, hence, would produce a null 'σ' exchange contribution to the K− optical potential in nuclear matter in a simple impulse approximation. This is a consequence of the fact that the leading order chiral Lagrangian gives an I=0 ππ→KK¯ amplitude proportional to the squared momentum transfer, q2. This finding poses questions on the meaning or the origin of 'σ' exchange potentials used in relativistic mean field approaches to the K− nuclear selfenergy. …
Study of the J/psi -> phi(omega) f(2)(1270), J/psi -> phi(omega) f '(2)(1525) and J/psi -> K*(0)(892) (K)over-bar(2)*(0)(1430) decays
We present an approach to Study the decay modes of the J/psi into a vector meson and a tensor meson, taking into account the nature of the f(2)(1270), f'(2)(1525). (K) over bar (2)*(0)(1430) resonances as dynamically generated states from the vector meson-vector meson interaction. We evaluate four ratios of partial decay widths in terms of a flavor dependent OZI breaking parameter and the results obtained compare favorably with experiment, although the experimental uncertainties are still large. Further refinements of the data Would provide a more stringent test on the theoretical approach. The fit to the data is possible due to the particular strength and sign of the couplings of the reson…
Delta rho pi Interaction Leading to N* and Delta* Resonances
We have performed a calculation for the three body Δρπ system by using the fixed center approximation to Faddeev equations, taking the interaction between Δ and ρ, Δ andπ, and ρ and π from the chiral unitary approach. We find several peaks in the modulus squared of the three-body scattering amplitude, indicating the existence of resonances, which can be associated to known I=1/2,3/2 and JP=1/2+,3/2+ and 5/2+ baryon states.
X(2175) as a resonant state of the phi K(K)overbar system
We perform a Faddeev calculation for the three mesons system, ϕKK¯, taking the interaction between two pseudoscalar mesons and between a vector and a pseudoscalar meson from the chiral unitary approach which generates dynamically the low lying scalar mesons in the first case and the low lying axial vector mesons in the second. We obtain a neat resonance peak around a total mass of 2150 MeV and an invariant mass for the KK¯ system around 970 MeV, very close to the f0(980) mass. The state appears in I=0 and qualifies as a ϕf0(980) resonance. No state is seen in I=1. This finding provides a natural explanation for the recent state found at BABAR and BES, the X(2175), which decays into ϕf0(980).
Prediction of an I=1 D(D)over-bar* state and relationship to the claimed Z(c)(3900), Z(c)(3885)
We study here the interaction of D (D) over bar* in the isospin I = 1 channel in light of recent theoretical advances that allow us to combine elements of the local hidden gauge approach with heavy quark spin symmetry. We find that the exchange of light q (q) over bar is Okubo-Zweig-Iizuka (OZI) suppressed and thus we concentrate on the exchange of heavy vectors and of two pion exchange. The latter is found to be small compared to the exchange of heavy vectors, which then determines the strength of the interaction. A barely D (D) over bar* bound state decaying into eta(c)rho and pi J/psi is found. At the same time we reanalyze the data of the BESIII experiment on e(+)e(-) -> pi(+/-)(D (D) o…
Limits to the fixed center approximation to Faddeev equations: The case of the phi(2170)
The Fixed Center Approximation to the Faddeev equations (FCA) has been used lately with success in the study of bound systems of three hadrons. It is also important to set the limits of the approach in those problems to prevent proliferation of inaccurate predictions. In this paper we study the case of the ϕ(2170), which has been described by means of Faddeev equations as a resonant state of ϕ and KK¯, and show the problems derived from the use of the FCA in its study. At the same time we also expose the limitations of an alternative approach recently proposed.
Novel Interpretation of the 'Theta(+)(1540) Pentaquark' Peak
We use a theoretical model of the gamma d --> K+K- np reaction adapted to the experiment done at LEPS where a peak was observed and associated with the Theta(+)(1540) pentaquark. The study shows that the method used in the experiment to assign momenta to the undetected proton and neutron, together with the chosen cuts, necessarily creates an artificial broad peak in the assumed K(+)n invariant mass in the region of the claimed Theta(+)(1540), such that the remaining strength seen for the experimental peak is compatible with a fluctuation of 2 sigma significance.
Plausible explanation for the Delta(5/2)+(2000) puzzle
From a Faddeev calculation for the π−(Δρ)N5/2−(1675) system we show the plausible existence of three dynamically generated I(JP)=3/2(5/2+) baryon states below 2.3 GeV whereas only two resonances, Δ5/2+(1905)(∗∗∗∗) and Δ5/2+(2000)(∗∗), are cataloged in the Particle Data Book Review. Our results give theoretical support to data analyses extracting two distinctive resonances, Δ5/2+(∼1740) and Δ5/2+(∼2200), from which the mass of Δ5/2+(2000)(∗∗) is estimated. We propose that these two resonances should be cataloged instead of Δ5/2+(2000). This proposal gets further support from the possible assignment of the other baryon states found in the approach in the I=1/2,3/2 with JP=1/2+,3/2+,5/2+ secto…
The role of f(0)(1710) in the phi omega threshold peak of J/Psi -> gamma phi omega
We study the process J/Psi -> 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 (K) over bar, but no trace of a peak is seen in the K (K) over bar spectrum of the J/Psi -> gamma K (K) over bar at this energy. This 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 performed on the production of a pair of vector mesons and how its interaction leads necessarily to a peak in the J/Psi ->…