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E. Oset

Publications and source records attributed to E. Oset.

At least 289 records · Page 16Linked to original sources
arXiv2009

Kaonic production of Lambda(1405) off deuteron target in chiral dynamics

The K^- induced production of Lambda(1405) is investigated in K^- d to pi Sigma n reactions based on coupled-channels chiral dynamics, in order to discuss the resonance position of the Lambda(1405) in the KbarN channel. We find that the K^-d to Lambda(1405)n process favors the production of Lambda(1405) initiated by the KbarN channel. The present approach indicates that the Lambda(1405) resonance position is 1420 MeV rather than 1405 MeV in the pi Sigma invariant mass spectra of K- d to pi Sigma n reactions. This is consistent with an observed spectrum of the K^- d to pi^+ Sigma^- n with 686-844 MeV/c incident K^- by bubble chamber experiments done in the 70's. Our model also reproduces the measured Lambda(1405) production cross section.

nucl-th↗
arXiv2009

The $γγ$ decay of the $f_0(1370)$ and $f_2(1270)$ resonances in the hidden gauge formalism

Using recent results obtained within the hidden gauge formalism for vector mesons, in which the $f_0(1370)$ and $f_2(1270)$ resonances are dynamically generated resonances from the $ρρ$ interaction, we evaluate the radiative decay of these resonances into $γγ$. We obtain results for the width in good agreement with the experimental data for the $f_2(1270)$ state and a width about a factor five smaller for the $f_0(1370)$ resonance, which would agree with preliminary results from the Belle collaboration, hinting at an order of magnitude smaller width for this resonance than for the $f_2(1270)$.

hep-ph↗
arXiv2009

The Y(3940), Z(3930) and the X(4160) as dynamically generated resonances from the vector-vector interaction

We study the vector-vector interaction within the framework of the hidden gauge formalism for the channels with quantum numbers Charm C=0 and Strangeness S=0 in the energy region around 4000 MeV. By looking for poles in the complex plane we find three resonances that could be identified by the mass, width and quantum numbers with the Y(3940), Z(3940) and X(4160), these poles appear with isospin I=0 and J^{PC}=0^{++}, 2^{++} and 2^{++} respectively. Whereas the Y(3940) and Z(3940) are coupled more strongly to D^*\bar{D}^*, the X(4160) is basically a D^*_s \bar{D}^*_s molecular state. Another two extra resonances appear in our approach with I=0, 1 and J^{PC}=1^{+-}, 2^{++} which are not found in the PDG with masses M=3945, 3912 MeV and widths Γ=0, 120 MeV respectively.

hep-ph↗
arXiv2009

Dynamically generated resonances

In this talk I report on recent work related to the dynamical generation of baryonic resonances, some made up from pseudoscalar meson-baryon, others from vector meson-baryon and a third type from two meson-one baryon systems. We can establish a correspondence with known baryonic resonances, reinforcing conclusions previously drawn and bringing new light on the nature of some baryonic resonances of higher mass.

hep-ph↗
arXiv2009

Charm at FAIR

Charmed mesons in hot and dense matter are studied within a self-consistent coupled-channel approach for the experimental conditions of density and temperature expected at the CBM experiment at FAIR/GSI. The $D$ meson spectral function broadens with increasing density with an extended tail towards lower energies due to $Λ_c(2593) N^{-1}$ and $Σ_c(2800) N^{-1}$ excitations. The in-medium $\bar D$ meson mass increases with density. We also discuss the consequences for the renormalized properties in nuclear matter of the charm scalar $D_{s0}(2317)$ and D(2400), and the predicted hidden charm X(3700) resonances at FAIR energies.

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arXiv2009

Testing the predicted dynamically generated hidden charm $X$ scalar state through the $D\bar D$ invariant mass spectrum and the radiative decay of the $ψ(3770)$

In this work we present our model that dynamically generates resonances from charmed and light pseudoscalar and vector mesons. The model generates a rich spectrum of charmed and hidden charm scalar and axial resonances, most of them which can be associated with observed states. Other states are predicted, in particular a hidden charm scalar resonance with mass close to the $D\bar D$ threshold. For this resonance we present calculations which show that an observed enhancement in the $D\bar D$ mass spectrum measured by Belle in reactions producing $D\bar D J/ψ$ in the final state could be originated by this predicted state. We also present theoretical calculations on the radiative decay width of the $ψ(3770)$ into this state. The predicted branching fractions suggest that this predicted state could be observed by BES with statistics of one year run in the $ψ(3770)$ peak.

hep-ph↗
arXiv2009

Dynamically generated resonances from the vector octet-baryon octet interaction

We study the interaction of vector mesons with the octet of stable baryons in the framework of the local hidden gauge formalism using a coupled channels unitary approach. We examine the scattering amplitudes and their poles, which can be associated to known J^P=1/2^-,3/2^- baryon resonances, in some cases, or give predictions in other ones. The formalism employed produces doublets of degenerate J^P=1/2^-,3/2^- states, a pattern which is observed experimentally in several cases. The findings of this work should also be useful to guide present experimental programs searching for new resonances, in particular in the strange sector where the current information is very poor.

hep-ph↗
arXiv2009

Dynamically generated resonances from vector meson-vector meson interaction based on a hidden-gauge unitary approach

We present a recent study of vector meson-vector meson interaction using a unitary approach based on the hidden-gauge Lagrangians. We find that 11 states get dynamically generated, corresponding to poles of the scattering matrices on the second Riemann sheet. Five of them are associated to the $f_0(1370)$, $f_0(1710)$, $f_2(1270)$, $f_2'(1525)$, and $K^*_2(1430)$, by comparing the mass, width, and decay pattern of these states with those of their experimental counterparts. Six others with the quantum numbers of $h_1$, $a_0$, $b_1$, $a_2$, $K^*_0$, and $K_1$ can not be clearly identified with any experimentally observed resonances and should be taken as predictions to be tested by future experiments.

hep-ph↗
arXiv2009

Vector meson-vector meson interaction in a hidden gauge unitary approach

The formalism developed recently to study vector meson--vector meson interaction, and applied to the case of $ρρ$, is extended to study the interaction of the nonet of vector mesons among themselves. The interaction leads to poles of the scattering matrix corresponding to bound states or resonances. We show that 11 states (either bound or resonant) get dynamically generated in nine strangeness-isospin-spin channels. Five of them can be identified with those reported in the PDG, i.e., the $f_0(1370)$, $f_0(1710)$, $f_2(1270)$, $f'_2(1525)$, and $K^*_2(1430)$. The masses of the latter three tensor states have been used to fine-tune the free parameters of the unitary approach, i.e., the subtraction constants in evaluating the vector meson -vector meson loop functions in the dimensional regularization scheme. The branching ratios of these five dynamically generated states are found to be consistent with data. The existence of the other six states should be taken as predictions to be tested by future experiments.

hep-ph↗
arXiv2009

Radiative decay into $γ$-baryon decuplet of dynamically generated resonances

We study the radiative decay into $γ$ and a baryon of the SU(3) decuplet of ten resonances that are dynamically generated from the interaction of vector mesons with baryons of the decuplet. We obtain quite different partial decay widths for the various resonances, and for different charge states of the same resonance, suggesting that the experimental investigation of these radiative decays should bring much information on the nature of these resonances.

hep-ph↗
arXiv2009

Scalar, axial-vector and tensor resonances from the rho D^*, omega D^* interaction in the hidden gauge formalism

We study composite systems of light ($ρ$ and $ω$) and heavy ($D^*$) vector mesons by using the interaction within the hidden gauge formalism. We find a strong attraction in the isospin, spin channels $(I,S)=(1/2,0)$; $(1/2,1)$; $(1/2,2)$ with positive parity. The attraction is large enough to strongly bind these mesons in states with these quantum numbers, leading to states which can be identified with $D_2^*(2460)$ and probably with $D^*(2640)$, the last one without experimental spin and parity assignment. In the case of $I=3/2$ one obtains repulsion and thus, no exotic mesons in this sector are generated in the approach.

hep-ph↗
arXiv2009

Searching for exotic states in the $N πK $ system

We study the $N πK$ system in order to investigate the possibility of existence of strangeness +1 resonance(s). The formalism consists of solving the Faddeev equations with the $N π$, $πK $ 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.

nucl-th↗
arXiv2009

Role of the $N^*$(1535) in the $J/ψ\to \bar{p}ηp$ and $J/ψ\to \bar{p}K^+Λ$ reactions

We study the $J/ψ\to \bar{p}ηp$ and $J/ψ\to \bar{p}K^+Λ$ reactions with a unitary chiral approach. We find that the unitary chiral approach, which generates the $N^*(1535)$ dynamically, can describe the data reasonably well, particularly the ratio of the integrated cross sections. This study provides further support for the unitary chiral description of the $N^*(1535)$. We also discuss some subtle differences between the coupling constants determined from the unitary chiral approach and those determined from phenomenological studies.

hep-ph↗
arXiv2009

ϕK^{+}K^{-} production in electron-positron annihilation

In this work we study the e^{+}e^{-}\toϕK^{+}K^{-} reaction. The leading order electromagnetic contributions to this process involve the γ*ϕ K^{+}K^{-} vertex function with a highly virtual photon. We calculate this function at low energies using RχPT supplemented with the anomalous term for the VV'P interactions. Tree level contributions involve the kaon form factors and the K*K transition form factors. We improve this result, valid for low photon virtualities, replacing the lowest order terms in the kaon form factors and K*K transition form factors by the form factors as obtained in UχPT in the former case and the ones extracted from recent data on e^{+}e^{-}\to KK* in the latter case. We calculate rescattering effects which involve meson-meson amplitudes. The corresponding result is improved using the unitarized meson-meson amplitudes containing the scalar poles instead of the lowest order terms. Using the BABAR value for BR(X\to ϕf_{0})Γ(X\to e^{+} e^{-}), we calculate the contribution from intermediate X(2175). A good description of data is obtained in the case of destructive interference between this contribution and the previous ones, but more accurate data on the isovector K*K transition form factor is required in order to exclude contributions from an intermediate isovector resonance to e^{+}e^{-}\to ϕ K^{+}K^{-} around 2.2 GeV.

hep-ph↗
arXiv2009

Meson and Baryon resonances

In this talk I review recent advances on the structure of the meson and baryon resonances which can be dynamically generated from the interaction of mesons or mesons and baryons. Particular emphasis is put on results involving vector mesons, which bring new light into the nature of some of the observed higher mass mesons and baryons and make predictions for new states.

hep-ph↗
arXiv2009

K- absorption in nuclei by two and three nucleons

It will be shown that the peaks in the (Lambda p) and (Lambda d) invariant mass distributions, observed in recent FINUDA experiments and claimed to be signals of deeply bound kaonic states, are naturally explained in terms of K- absorption by two or three nucleons leaving the rest of the original nuclei as spectator. For reactions on heavy nuclei, the subsequent interactions of the particles produced in the primary absorption process with the residual nucleus play an important role. Our analyses leads to the conclusion that at present there is no experimental evidence of deeply bound K- state in nuclei. Although the FINUDA experiments have been done for reasons which are not supported a posteriori, some new physics can be extracted from the data.

nucl-th↗
arXiv2008

An explanation of the $Δ_{5/2^{-}}(1930)$ as a $ρΔ$ bound state

We use the $ρΔ$ interaction in the hidden gauge formalism to dynamically generate $N^{\ast}$ and $Δ^{\ast}$ resonances. We show, through a comparison of the results from this analysis and from a quark model study with data, that the $Δ_{5/2^{-}}(1930),$ $Δ_{3/2^{-}}(1940)$ and $Δ_{1/2^{-}}(1900)$ resonances can be assigned to $ρΔ$ bound states. More precisely the $Δ_{5/2^{-}}(1930)$ can be interpreted as a $ρΔ$ bound state whereas the $Δ_{3/2^{-}}(1940)$ and $Δ_{1/2^{-}}(1900)$ may contain an important $ρΔ$ component. This interpretation allows for a solution of a long-standing puzzle concerning the description of these resonances in constituent quark models. In addition we also obtain degenerate $J^{P}=1/2^{-},3/2^{-},5/2^{-}$ $N^{*}$ states but their assignment to experimental resonances is more uncertain.

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