E. Oset's research while affiliated with Guangxi Normal University and other places

Publications (121)

Article
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We study the \(\tau \rightarrow \nu _\tau A\) decay, with A an axial-vector meson. We produce the \(a_1(1260)\) and \(b_1(1235)\) resonances in the Cabibbo favored mode and two \(K_1(1270)\) states in the Cabibbo suppressed mode. We take advantage of previous chiral unitary approach results where these resonances appear dynamically from the vector...
Article
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We study the J/ψ→γπ+π−, γπ0η reactions from the perspective that they come from the J/ψ→ϕ(ω)π+π−,ρ0π0η reactions, where the ρ0, ω, and ϕ get converted into a photon via vector meson dominance. Using models successfully used previously to study the J/ψ→ω(ϕ)ππ reactions, we make determinations of the invariant mass distributions for π+π− in the regio...
Article
We study the \( B^{+} \rightarrow J/\psi \omega K^{+}\) reaction, and show that it is driven by the presence of two resonances, the X(3940) and X(3930), that are of molecular nature and couple most strongly to \( D^{\ast} \bar{D}^{\ast}\), but also to \( J/\psi\omega\). Because of that, in the \( J/\psi\omega\) mass distribution we find a peak rela...
Article
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We study the weak decay Ωb−→(Ξc+K−)π−, in view of the narrow Ωc states recently measured by the LHCb Collaboration and later confirmed by the Belle Collaboration. The Ωc(3050) and Ωc(3090) are described as meson-baryon molecular states, using an extension of the local hidden gauge approach in coupled channels. We investigate the ΞD, ΞcK¯, and Ξc′K¯...
Article
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We perform a study of the B(*), D(*) semileptonic decays, using a different method than in conventional approaches, where the matrix elements of the weak operators are evaluated and a detailed spin-angular momentum algebra is performed to obtain very simple expressions at the end for the different decay modes. Using only one experimental decay rate...
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We have investigated Ωc states that are dynamically generated from the meson-baryon interaction. We use an extension of the local hidden gauge to obtain the interaction from the exchange of vector mesons. We show that the dominant terms come from the exchange of light vectors, where the heavy quarks are spectators. This has as a consequence that he...
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We have addressed the study of non-leptonic weak decays of heavy hadrons ($\Lambda_b, \Lambda_c, B$ and $D$), with external and internal emission to give two final hadrons, taking into account the spin-angular momentum structure of the mesons and baryons produced. A detailed angular momentum formulation is developed which leads to easy final formul...
Article
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We study the \(B_c^- \rightarrow \pi ^- J/\psi \omega \) and \(B_c^- \rightarrow \pi ^- D^* \bar{D}^*\) reactions and show that they are related by the presence of two resonances, the X(3940) and X(3930), that are of molecular nature and couple most strongly to \(D^* \bar{D}^*\), but also to \(J/\psi \omega \). Because of that, in the \(J/\psi \ome...
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Using the local hidden gauge approach, we study the possibility of the existence of bottomed strange molecular states with isospin 0. We find three bound states with spin-parity $0^+$, $1^+$ and $2^+$ generated by the $\bar{K}^*B^*$ and $\omega B_s^*$ interaction, among which the state with spin 2 can be identified as $B_{s2}^*(5840)$. In addition,...
Conference Paper
In this talk we review the theoretical predictions for ratios of branching fractions of B ¯ 0 decays into D 0 and the scalar mesons f 0(500), f 0(980), a 0(980), plus B ¯ S 0 decay into D 0 and κ(800). We also compare the π + π − production in the scalar channel with that observed in the ρ channel and make predictions for the B ¯ 0 S d...
Conference Paper
We have investigated the decays of B ¯ 0 → K ¯ * 0 R and B ¯ s 0 → ϕ R with R being the X(4160), Y(3940), Z(3930) and a predicted J = 1 resonances. By using a model in which these states are dynamically generated from the vector-vector interaction, most notably the D * D ¯ * and D s * D ¯ s * states, we predicted five ratios...
Article
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We have studied the $B\bar{B}^*$ and $B^*\bar{B}^*$ interactions for isospin I = 1 using the Local Hidden gauge approach. Since both interactions via one light meson exchange are not allowed by Okubo-Zweig-Iizuka (OZI) rule, we investigated the contributions for those interactions coming from two pions, interacting and noninteracting among themselv...
Article
Assuming that the f2′(1525), a2(1320), and K2*(1430) resonances are dynamically generated states from vector-meson–vector-meson interactions in the s-wave with spin S=2, we study the γp→f2′(1525)p, γp→a20(1320)p, and γp→K2*(1430)Λ(Σ) reactions. These reactions proceed in the following way: the incoming photon first mutates into a ρ0, ω, or ϕ meson...
Article
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We study the interaction of the a $\rho$ and $D^*$, $\bar D^*$ with spins aligned using the Fixed Center Approximation to the Faddeev equations. We select a cluster of $D^* \bar D^*$, which is found to be bound in $I=0$ and can be associated to the X(3915), and let the $\rho$ meson orbit around the $D^*$ and $\bar D^*$. In this case we find an $I=1...
Article
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We extend a recent approach to describe the $B^0$ and $B^0_s$ decays into $J/\psi$ $f_0(500)$ and $J/\psi$ $f_0(980)$, relating it to the $B^0$ and $B^0_s$ decays into $J/\psi$ and a vector meson, $\phi$, $\rho$, $K^*$. In addition the $B^0$ and $B^0_s$ decays into $J/\psi$ and $\kappa(800)$ are evaluated and compared to the $K^*$ vector production...
Article
We evaluate energy levels of the ππ system in the ρ channel in a finite volume using chiral unitary theory. We investigate ππ phase shifts and ρ meson properties using Lattice QCD data with high precision. We also shortly discuss the πK system in the K* channel in a finite volume.
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We apply an extension of the Weinberg compositeness condition on partial waves of L=1 and resonant states to determine the amount of meson-baryon component in the $\Delta(1232)$ resonance and the other members of the $J^P= 3/2^+$ baryon decuplet. We obtain an appreciable amount of $\pi N$ in the $\Delta(1232)$ wave function, of the order of 70%, an...
Article
A coupled channel model for the interaction of vector mesons with baryons is employed in the study of the γp → K0Σ+ reaction around the K*Λ and K*Σ thresholds, where the recent CBELSA/TAPS cross section shows a sudden drop and the differential cross section experiences a transition from a forward-peaked distribution to a flat one. A delicate interf...
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The BES data on the J/ψ→ηK⁎0K reaction show a clear enhancement in the K⁎0K mass distribution close to the threshold of this channel. Such an enhancement is usually a signature of an L=0 resonance around threshold, which in this case would correspond to an h1 state with quantum numbers IG(J)=0-(1). A state around 1800 MeV results from the interacti...
Article
In the present work we investigate the three-body systems of ηKK¯ and η'KK¯, by taking the fixed center approximation to Faddeev equations. We find a clear and stable resonance structure around 1490 MeV in the squared ηKK¯ scattering amplitude, which is not sensitive to the renormalization parameters. Conversely, we get only an enhancement effect o...
Article
We present the Fixed Center Approximation (FCA) to the Faddeev equations for the K¯NN system with S=0S=0, including the charge exchange mechanisms in the K¯ rescattering. The system appears bound by about 35 MeV and the width, omitting two body absorption, is about 50 MeV. We also evaluate the K¯ absorption width in the bound K¯NN system by employi...
Article
We have investigated a charmed system of DNN (composed of two nucleons and a D meson) by a complementary study with a variational calculation and a Faddeev calculation with fixed-center approximation (Faddeev-FCA). In the present study, we employ a DN potential based on a vector–meson exchange picture in which a resonant Λc(2595)Λc(2595) is dynamic...
Article
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We report on a recent calculation of the properties of the $DNN$ system, a charmed meson with two nucleons. The system is analogous to the $\bar K NN$ system substituting a strange quark by a charm quark. Two different methods are used to evaluate the binding and width, the Fixed Center approximation to the Faddeev equations and a variational calcu...
Article
We extend the Fixed Center Approximation (FCA) to the Faddeev Equations for the $\bar{K} NN$ system with S=0, including the charge exchange mechanisms in the $\bar{K}$ rescattering which have been ignored in former works within the FCA. We obtain similar results to those found before, but the binding is reduced by 6 MeV. At the same time we also ev...
Article
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In this work baryon systems made of three hadrons which contain one nucleon and one D meson, and in addition another meson, bar D, K or bar K, are investigated using the Fixed Center Approximation to the Faddeev equations. In this work we use Λc(2595), X(3700) and D*s0(2317) bound states as a cluster and a third particle scattering form that cluste...
Article
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We present a way to evaluate the scattering of unstable particles quantized in a finite volume with the aim of extracting physical observables for infinite volume from lattice data. We illustrate the method with the $\pi\rho$ scattering which generates dynamically the axial-vector $a_1(1260)$ resonance. Energy levels in a finite box are evaluated b...
Article
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In this talk we report on selected topics on hadrons in nuclei. The first topic is the renormalization of the width of the $\Lambda(1520)$ in a nuclear medium. This is followed by a short update of the situation of the $\omega$ in the medium. The investigation of the properties of $\bar{K}$ in the nuclear medium from the study of the $(K_{flight},p...
Article
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The interaction between various charmed mesons and charmed baryons is studied within the framework of the coupled-channel unitary approach with the local hidden gauge formalism. Several meson-baryon dynamically generated narrow N* and Λ* resonances with hidden charm are predicted with mass above 4 GeV and width smaller than 100 MeV. The predicted n...
Article
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We determine the radiative decay amplitudes for the decay into D* and [`(D)] \bar{{D}} g \gamma , or D * s and [`(D)]s \bar{{D}}_{s}^{} g \gamma of some of the charmonium-like states classified as X , Y , Z resonances, plus some other hidden charm states which are dynamically generated from the interaction of vector mesons with charm. The mass dist...
Article
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The key question of this letter is whether the K −-nucleus optical potential is deep, as it is prefered by the phenomenological fits to kaonic atoms data, or shallow, as it comes out from unitary chiral model calculations. The current experimental situation is reviewed.
Article
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We study the properties of charmed hadrons in dense matter within a coupled-channel approach which accounts for Pauli blocking effects and meson self-energies in a, self-consistent manner. We analyze the behaviour in this dense environment of dynamically-generated baryonic resonances as well as the open-charm meson spectral functions. We discuss th...
Article
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We study the (K-,p) reaction on nuclei with a 1 GeV/c momentum kaon beam, paying a special attention at the region of emitted protons having kinetic energy above 600 MeV, which was used to claim a deeply attractive kaon nucleus optical potential. Our model describes the nuclear reaction in the framework of a local density approach and the calculati...
Article
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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...
Article
6 pages, 1 table.-- PACS nrs.: 13.75.Lb, 14.40.Cs, 12.40.Vv, 12.40.Yx.-- Talk at the 2008 International Conference on Particles And Nuclei (PANIC08, Nov 9-14, 2008, Eilat, Israel). 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...
Article
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 $f_2(1270)$, $f'_2(1525)$, $\bar{K}^{* 0}_2(1430)$ resonances as dynamically generated states from the vector meson-vector meson interaction. We evaluate four ratios of partial decay widths in terms of a flav...
Article
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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 $f_0(1370)$, $f_0(1710)$, $f_2(1270)$, $f_2'(1525)$, an...
Article
We study the radiative decay into $\gamma$ 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 exper...
Article
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We provide a series of arguments which support the idea that the peak seen in the $\gamma p \to K^+ \Lambda$ reaction around 1920 MeV should correspond to the recently predicted state of $J^P=1/2^+$ as a bound state of $K \bar{K}N$ with a mixture of $a_0(980)N$ and $f_0(980)N$ components. At the same time we propose polarization experiments in that...
Article
The formalism developed recently to study vector meson--vector meson interaction, and applied to the case of $\rho\rho$, 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 res...
Article
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We study the reactions J/ψ → \( \bar \Lambda \) K -p and J/ψ → \( \bar \Lambda \)π+π-Λ with a unitary chiral approach. We predict the ratio of the invariant-mass distributions of these two reactions at the Λ(1520) peak position, which is free of the unknown production mechanism and reflects only the properties of the Λ(1520) . An experimental measu...
Article
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In view of the recent experimental developments in the η→π0γγ decay, and the fact that the Particle Data Group in the online edition of 2007 reports sizable changes of the radiative decay widths of vector mesons used as input in the theoretical calculations of E. Oset, J. R. Pelaez, and L. Roca [ Phys. Rev. D 67 073013 (2003)], a reevaluation of th...
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The analysis of the gammap-->etapi(0)p reaction has been performed using data from the GRAAL experiment. The total and differential cross sections and the beam asymmetry have been obtained from threshold up to 1.5 GeV of beam energy. The two resonances S11(1535) and Delta(1700) are expected to be excited in the intermediate states of this reaction....
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We calculate the radiative decay widths of the a 0(980) and f 0(980) scalar mesons into ργ and ωγ considering the dynamically generated nature of these scalar resonances within the realm of the chiral unitary approach. The main ingredient in the evaluation of the radiative width of the scalar mesons are the loops coming from the decay into their co...
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10 pages, 10 figures.-- PACS nrs.: 13.60.Le; 25.20.Lj; 36.10.Gv; 14.40.Cs.-- ISI Article Identifier: 000247625200045.-- ArXiv pre-print available at: http://arxiv.org/abs/nucl-th/0610085 We perform calculations for ω production in nuclei by means of the (γ,p) reaction for photon energies and proton angles suited to currently running and future expe...
Chapter
We critically revise the recent claims of a deeply bound K − pp state associated to a peak seen in the Λp invariant-mass spectrum following nuclear K − absorption reactions measured by the FINUDA Collaboration. An explicit theoretical simulation shows that the peak is simply generated from a two-nucleon absorption process, like K − pp → Λp, followe...
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10 pages, 4 figures.-- ISI Article Identifier: 000251895400004.-- ArXiv pre-print available at: http://arxiv.org/abs/hep-ph/0611075 Printed version published on Dec 13, 2007. A previous model where the low-lying axial-vector mesons are dynamically generated, implementing unitarity in coupled channels in the vector-pseudoscalar (VP) meson interactio...
Article
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 $\Lambda(1405)$ states, the interaction of the octet of pseudoscalar...
Article
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In this talk I report on selected topics of hadron modification in the nuclear medium using the chiral unitary approach to describe the dynamics of the problems. I shall mention how antikaons, η and φ are modified in the medium and will report upon different experiments done or planned to measure the φ width in the medium.
Article
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We make a critical analysis on the theoretical calculations that lead to predictions of deeply bound kaonic states in nuclei. The model set-up, after dropping several important processes and channels, leads unavoidably to an unrealistic deep potential with a very small imaginary part. We review also the experimental results taken as reference for t...
Article
We present results on the production of bound states of Θ+ in nuclei using the (K+,π+) reaction. By taking into account the states obtained within a wide range of strength of the Θ+ nucleus optical potential, plus the possibility to replace different nucleons of the nucleus, we obtain an excitation spectra with clearly differentiated peaks. The mag...
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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 ($\sigma$ 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...
Article
By using a relativistic framework and accurate nuclear spectral function the structure functions F2A andF 3A of deep inelastic charged lepton and neutrino scattering are calculated in nuclei and results are presented.
Article
Based on a prior determination of the $\phi$ selfenergy in a nuclear medium we perform a theoretical study of inclusive $\phi$ photoproduction in nuclei, looking at the $A$ dependence of the cross sections for different $\phi$ momenta. We find sizeable reductions in the nuclear cross sections with respect to the elementary one, using a $\phi$ selfe...
Article
Using a chiral unitary approach for the meson–baryon interactions, we show that two octets of Jπ=1/2− baryon states, which are degenerate in the limit of exact SU(3) symmetry, and a singlet are generated dynamically. The SU(3) breaking produces the splitting of the two octets, resulting in the case of strangeness S=−1 in two poles of the scattering...
Chapter
We perform a study of the final-state interactions of the K +\({\bar K^0}\) and the \({\bar K^0}\) d systems in the reactions pp → dK +\({\bar K^0}\) and pp → dπ+η. The interactions of the mesons are accounted for by using chiral unitary techniques, which generate dynamically the a 0(980)-resonance, and the \({\bar K^0}\) d interaction is also take...
Article
We evaluate radiative decays of ρ and ω going to two neutral mesons, π0π0 and π0η. We use the sequential vector decay mechanisms in addition to chiral loops and ρ- ω mixing. The chiral loops are obtained using elements of U χPT successfully applied in the study of meson-meson interactions up to 1.2 GeV. The chiral loops are found very important in...
Article
We evaluate the p-wave K−N amplitudes from the chiral Lagrangians and from there construct the p-wave part of the K− nucleus optical potential plus a small s-wave part induced from the elementary p-wave amplitude and the nuclear Fermi motion. Simultaneously, the momentum and energy dependence of the s-wave optical potential, previously developed, a...
Article
We study the (γ,p) reaction on 208Pb leading to 207Pb with a bound pion attached to it in the lowest 1s or 2p pionic levels. The reaction can be made recoilless to optimize the production cross section but we must choose a bit higher photon energy to overcome the Coulomb barrier in the proton emission. The cross sections obtained are easily measura...
Article
We perform a study of the final-state interactions of the K + and the d systems in the reactions pp↦dK + and pp↦dπ+η. Since the two-meson system couples strongly to the a 0(980) resonance, these reactions are expected to be an additional source of information about the controversial scalar sector. We also show that these reactions present peculiar...
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We develop a unitarity approach to consider the final state interaction corrections to the tree level graphs calculated from Chiral Perturbation Theory ($\chi PT$) allowing the inclusion of explicit resonance fields. The method is discussed considering the coupled channel pion and kaon vector form factors. These form factors are then matched with t...
Article
Using a chiral unitary model in which the negative parity nucleon resonance N∗≡N∗(1535) is generated dynamically by means of the Bethe–Salpeter equation with coupled meson–baryon channels in the S=0 sector, we have obtained the π0N∗N∗ and ηN∗N∗ couplings. The π0N∗N∗ coupling has smaller strength but the same sign as the π0NN coupling. This rules ou...
Article
We have studied the structure and formation of mesic atoms and mesic nuclei theoretically. The latest results on the deeply bound pionic atoms, the kaonic atoms and the sigma states are reported.
Article
The charge changing weak production of Delta in nucleons and nuclei is studied. The reactions e^{-} p -> Delta^{0} \nu_{e} and e^{+} p -> Delta^{++} \bar{\nu}_{e} are considered as a possible source of information about the weak N-Delta transition form factors. The low q^2 BNL data on neutrino production of Delta are used to extract the axial vecto...
Article
We study the ρ0 and φ decays into π+π−γ, π0π0γ and φ into π0ηγ using a chiral unitary approach to deal with the final state interaction of the MM system. The final state interaction modifies only moderately the large momenta tail of the photon spectrum of the ρ0→π+π−γ decay. In the case of φ decay the contribution to π+π−γ and π0π0γ decay proceeds...
Article
By means of a coupled channel non-perturbative unitary approach, it is possible to extend the strong constrains of Chiral Perturbation Theory to higher energies. In particular, it is possible to reproduce the lowest lying resonances in meson-meson scattering up to 1.2 GeV using the parameters of the O(p2) and O(p4) Chiral Lagrangian. The meson bary...
Article
We study the vector and scalar meson-meson amplitudes up to \sqrt{s}\lesssim 1.4 GeV and their associated spectroscopy. The study has been done considering jointly the N/D method, Chiral Symmetry and implications from large N_c QCD. The N/D method provides us with the way to unitarize the tree level amplitudes constructed in agreement with Chiral S...
Article
We report on recent progress on the chiral unitary approach, analogous to the effective range expansion in Quantum Mechanics, which is shown to have a much larger convergence radius than ordinary chiral perturbation theory, allowing one to reproduce data for meson meson interaction up to 1.2 GeV. Applications to physical processes so far unsuited f...
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We have developed a model for the N N --> N N pi pi reaction and evaluated cross sections for the different charged channels. The low energy part of those channels where the pions can be in an isospin zero state is dominated by N* excitation, driven by an isoscalar source followed by the decay N* --> N (pi pi, T=0, s-wave). At higher energies, and...
Article
The neutrino production of Delta in O-16 has been studied at intermediate energies relevant to atmospheric neutrino experiments. The Delta production cross sections with electrons or muons in the final state is found to be reduced due to nuclear effects. This reduction is even larger for the accompanying one pion production cross sections. The rati...
Article
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We have developed a model for the N N --> N N pi pi reaction and evaluated cross sections for the different charged channels. The low energy part of those channels where the pions can be in an isospin zero state is dominated by N* excitation, driven by an isoscalar source recently found experimentally, followed by the decay N* --> N (pi pi, T=0, s-...
Article
We revise the conventional nuclear effects of Fermi motion, binding and pionic effects in deep inelastic lepton scattering using a relativistic formalism for an interacting Fermi sea and the local density approximation to translate results from nuclear matter to finite nuclei. In addition we also consider effects from ϱ-meson renormalization in the...
Article
Two types of coherent pion production in heavy-ion collisions are studied and calculations are performed for 12C against 12C collisions. The first one, doubly coherent production, produces a pion in one nucleus leaving it in its ground state, while the second nucleus is excited to the 1+, T = 1 state. The second process, semicoherent production, al...
Article
The nuclear structure function F2A(x) has been studied in the Bjorken limit for (l, l′) scattering on nuclei in the region of x > 1 and was found to be very sensitive to the information contained in the nucleon spectral function in nuclei, particularly the correlations between momenta and energies in the region of large momenta. Calculations were d...