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M. J. Vicente Vacas

Publications and source records attributed to M. J. Vicente Vacas.

At least 91 records · Page 5Linked to original sources
arXiv2007

Recent Developments in Chiral Unitary Dynamics of Resonances

In this talk I summarize recent findings made on the description of axial vector mesons as dynamically generated states from the interaction of peseudoscalar mesons and vector mesons, dedicating some attention to the two $K_1(1270)$ states. Then I review the generation of open and hidden charm scalar and axial states. Finally, I present recent results showing that the low lying $1/2^+$ baryon resonances for S=-1 can be obtained as bound states or resonances of two mesons and one baryon in coupled channels dynamics.

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arXiv2007

Dynamically generated open and hidden charm mesons

In this presentation I explain our framework for dynamically generating resonances from the meson meson interaction. Our model generates many poles in the T-matrix which are associated with known states, while at the same time new states are predicted.

hep-ph↗
arXiv2007

Neutrino-induced coherent pion production

We have investigated the neutrino induced coherent pion production reaction at the energies of interest for recent experiments like K2K and MiniBooNE. The model includes pion, nucleon and the Delta(1232) resonance. Medium effects in the production mechanism and the distortion of the pion wave function are taken into account. We find a strong reduction of the cross section due to these effects and also substantial modifications in the energy distributions of the final pion. The sensitivity of the results on the axial N-Delta coupling C5A(0) and the coherent fraction in neutral-current pi0 production are discussed.

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arXiv2007

Coherent pion production in neutrino-nucleus collisions

We have investigated the neutrino induced coherent pion production reaction at low and intermediate energies including pion, nucleon and Delta(1232) resonance. Medium effects in the production mechanism and the distortion of the pion wave function are included in the calculation. We find a strong reduction of the cross section due to these effects and also substantial modifications in the energy distributions of the final pion. The dependence on the atomic number is discussed.

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arXiv2007

Charged current neutrino induced coherent pion production

We analyze the neutrino induced charged current coherent pion production at the energies of interest for recent experiments like K2K and MiniBooNE. Medium effects in the production mechanism and the distortion of the pion wave function, obtained solving the Klein Gordon equation with a microscopic optical potential, are included in the calculation. We find a strong reduction of the cross section due to these effects and also substantial modifications of the energy distributions of the final lepton and pion.

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arXiv2007

Dynamically Generated Open and Hidden Charm Meson Systems

We will study open and hidden charm scalar meson resonances within two different models. The first one is a direct application of a chiral Lagrangian already used to study flavor symmetry breaking in Skyrme models. In another approach to the problem a SU(4) symmetric Lagrangian is built and the symmetry is broken down to SU(3) by identifying currents where heavy mesons are exchanged and suppressing those. Unitarization in couple channels leads to dynamical generation of resonances in both models, in particular a new hidden charm resonance with mass 3.7 GeV is predicted. The small differences between these models and with previous works will be discussed.

hep-ph↗
arXiv2007

Recent developments in chiral dynamics of hadrons and hadrons in nuclei

In this talk I present recent developments in the field of hadronic physics and hadrons in the nuclear medium. I review the unitary chiral approach to meson baryon interaction and address the topics of the two dynamically generated $Λ(1405)$ resonances, with experiments testing it, the $Λ(1520)$ and $Δ(1700)$ resonances, plus the $Λ(1520)$, $Σ(1385)$ and $ω$ in the nuclear medium.

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arXiv2006

The baryon-decuplet in the chiral dynamics of Lambda-hyperons in nuclear matter

We study the long range part of the $Λ$-hyperon optical potential in nuclei using Quantum Many Body techniques and flavor-SU(3) Chiral Lagrangians as starting point. More precisely, we study the contributions to the $Λ$-hyperon optical potential due to the long-range two-pion exchange, with $Σ$ and $Σ^*$ baryons in the internal baryonic lines and considering Nh and $Δ$h excitations. We also consider the contribution to the spin-orbit potentials that comes out from these terms. Our results support a natural explanation of the smallness of the $Λ$-nuclear spin-orbit interaction and shows the importance of the $Σ^*$ and $Δ$ degrees of freedom for the hyperon-nucleus interactions.

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arXiv2006

Hadron spectrum and hadrons in the nuclear medium

Some recent developments in chiral dynamics of hadrons and hadrons in a medium are presented. Unitary schemes based on chiral Lagrangians describe some hadronic states as being dynamically generated resonances. We discuss how standard quantum many body techniques can be used to calculate the properties of these dynamically generated and other hadrons in the nuclear medium. We present some results for vector mesons ($ρ$ and $ϕ$), scalar mesons ($σ$, $κ$, $a_0(980)$, $f_0(980)$), the $Λ(1520)$ and for the in-medium baryon-baryon interaction.

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arXiv2006

Scalar Lambda N and Lambda Lambda interaction in a chiral unitary approach

We study the central part of Lambda N and Lambda Lambda potential by considering the correlated and uncorrelated two-meson exchange besides the omega exchange contribution. The correlated two-meson is evaluated in a chiral unitary approach. We find that a short range repulsion is generated by the correlated two-meson potential which also produces an attraction in the intermediate distance region. The uncorrelated two-meson exchange produces a sizeable attraction in all cases which is counterbalanced by omega exchange contribution.

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arXiv2006

Recent developments in chiral dynamics of hadrons and hadrons in a nuclear medium

In this talk I present recent developments in chiral dynamics of hadrons and hadrons in a medium addressing the following points: interaction of the octet of pseudoscalar mesons with the octet of baryons of the nucleon, showing recent experimental evidence on the existence of two $Λ(1405)$ states, the interaction of the octet of pseudoscalar mesons with the decuplet of baryons of the $Δ$, with particular emphasis on the $Λ(1520)$ resonance, dynamically generated by this interaction. Then I review the interaction of kaons in a nuclear medium and briefly discuss the situation around the claims of deeply bound states in nuclei. The large renormalization of the $Λ(1520)$ in the nuclear medium is shown as another example of successful application of the chiral unitary techniques.

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arXiv2006

Weak Quasi-elastic Production of Hyperons

The quasielastic weak production of $Λ$ and $Σ$ hyperons from nucleons and nuclei induced by antineutrinos is studied in the energy region of some ongoing neutrino oscillation experiments in the intermediate energy region. The hyperon nucleon transition form factors determined from neutrino nucleon scattering and an analysis of high precision data on semileptonic decays of neutron and hyperons using SU(3) symmetry have been used. The nuclear effects due to Fermi motion and final state interaction effects due to hyperon nucleon scattering have also been studied. The numerical results for differential and total cross sections have been presented.

hep-ph↗
arXiv2006

Charged and Neutral Current Neutrino Induced Nucleon Emission Reactions

By means of a Monte Carlo cascade method, to account for the rescattering of the outgoing nucleon, we study the charged and neutral current inclusive one nucleon knockout reactions off nuclei induced by neutrinos. The nucleon emission process studied here is a clear signal for neutral--current neutrino driven reactions, and can be used in the analysis of future neutrino experiments.

hep-ph↗
arXiv2006

Inclusive Nucleon Emission Induced by Quasi--Elastic Neutrino--Nucleus Interactions

We study the quasi--elastic contribution to the inclusive $(ν_l,ν_l N)$, $(ν_l,l^- N)$, $({\bar ν}_l,{\bar ν}_l N)$ and $({\bar ν}_l,l^+ N)$ reactions in nuclei using a Monte Carlo simulation method to account for the rescattering of the outgoing nucleon. As input, we take the reaction probability from the microscopical many body framework developed in Phys. Rev. {\bf C70} (2004) 055503 for charged-current induced reactions, while for neutral currents we use results from a natural extension of the model described in that reference. The nucleon emission process studied here is a clear signal for neutral--current neutrino driven reactions, that can be used in the analysis of future neutrino experiments.

hep-ph↗
arXiv2006

Two pion mediated scalar isoscalar NN interaction in the nuclear medium

We study the modification of the nucleon nucleon interaction in a nuclear medium in the scalar isoscalar channel, mediated by the exchange of two correlated ($σ$ channel) or uncorrelated pions. For this purpose we use a standard approach for the renormalization of pions in nuclei. The corrections obtained for the $NN$ interaction in the medium in this channel are of the order of 20% of the free one in average, and the consideration of short range correlations plays an important role in providing these moderate changes. Yet, the corrections are sizable enough to suggest further studies of the stability and properties of nuclear matter.

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arXiv2005

Baryonic Resonances from the Interactions of the Baryon Decuplet and Meson Octet

We study $S$-wave interactions of the baryon decuplet with the octet of pseudoscalar mesons using the lowest order chiral Lagrangian. We find two bound states in the SU(3) limit corresponding to the octet and decuplet representations. These are found to split into eight different trajectories in the complex plane when the SU(3) symmetry is broken gradually. Finally, we are able to provide a reasonable description for a good number of 4-star ${3/2}^-$ resonances listed by the Particle Data Group. In particular, the $Ξ(1820)$, the $Λ(1520)$ and the $Σ(1670)$ states are well reproduced. We predict a few other resonances and also evaluate the couplings of the observed resonances to the various channels from the residues at the poles of the scattering matrix from where partial decay widths into different channels can be evaluated.

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arXiv2005

Chiral dynamics of the $Λ(1520)$ in coupled channels tested in the $K^-p\toππΛ$ reaction

The $Λ(1520)$ resonance is generated dynamically in a unitary coupled channel framework with the $πΣ^*$ and $KΞ^*$ channels in s-wave and $πΣ$ and $\bar K N$ channels in d-wave. The dynamics of this resonance close to and above threshold is then tested through the reactions $K^-p\toππΛ$ and a good agreement with the experimentally measured cross section is observed.

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