Three-body calculations of $K\bar{K}N$ system with quantum numbers $I=1/2$, $J^π=(\frac{1}{2})^{+}$ were performed. Using separable potentials for two-body interactions, we calculated the $πΣ$ mass spectra for the $(\bar{K}N)_{I=0}+K^{+}\rightarrow(πΣ)^{0}K^{+}$ reaction on the basis of three-body Alt-Grassberger-Sandhas equations in the momentum representation. In this regard, different types of $\bar{K}N-πΣ$ potentials based on phenomenological and chiral SU(3) approach are used. The possibility to observe the trace of $Λ(1405)$ resonance in $(πΣ)^{0}$ mass spectra was studied. Using the $χ^{2}$ fitting, it was shown that the mass of $Λ$(1405) resonance is about 1417 $\mathrm{MeV}/c^{2}$.
The method based on microscopic theory of nuclear reactions has been applied for the analysis of parity violating effects in a few-body systems. Different parity violating and parity conserving asymmetries and their dependence on neutron energy have been estimated for $n + ^3He \rightarrow ^3H + p$ reaction. The estimated effects are in a good agreement with available exact calculations.
Cross-section, vector-polarization, and tensor-polarization distributions are calculated for the reactions $e^+ e^- \rightarrow \bar{p}p$ and $e^+ e^- \rightarrow \barΛ Λ$. Each reaction requires six characteristic functions that are bilinear in the, possibly complex, electromagnetic form factors, denoted $G_E(P^2)$ and $G_M(P^2)$, of $p$ and $Λ$. For the hyperon reaction also the joint-decay distributions of $Λ$ and $\barΛ$ are calculated. Their knowledge allow a complete determination of the hyperon electromagnetic form factors, without measuring hyperon spins. We explain how this is done in…
Using expansion of the three-body wave function of the $pep$ system in the initial state on hyperharmonic functions, the rate of the $p+p+e^{-} \rightarrow d+ν_e$ reaction in the Sun is calculated. The results of calculation of the flux at 1 AU are compared with the results of a measurement made by the Borexino collaboration and Bahcall \textit{et al.} theoretical predictions.
The elementary production cross sections $πΔ\rightarrow Y K$ $(Y=Σ,\,\, Λ)$ and $πN \rightarrow Y K$ are needed to describe kaon production in heavy ion collisions. The $πN \rightarrow Y K$ reactions were studied previously by a resonance model. The model can explain the experimental data quite well \cite{tsu}. In this article, the total cross sections $πΔ\rightarrow Y K$ at intermediate energies (from the kaon production threshold to3 GeV of $πΔ$ center-of-mass energy) are calculated for the first time using the same resonance model. The resonances, $N(1710)\,I(J^P) = \frac{1}{2}(\frac{1}{2}^…
In present work, we investigated $K^{-}+\, ^{3}\mathrm{He}$ reaction at low energies. The coupled-channel Faddeev AGS equations were solved for $\bar{K}Nd-πΣ{d}$ three-body system in momentum representation to extract the scattering amplitudes. To trace the signature of the $Λ$(1405) resonance in the $πΣ$ invariant mass, the deuteron energy spectrum for $K^{-}+\,^{3}\mathrm{He}\rightarrowπΣ{d}$ reaction was obtained. Different types of $\bar{K}N-πΣ$ potentials based on phenomenological and chiral SU(3) approaches were used. As a remarkable result of this investigation, it was found that the de…
The reaction $np \rightarrow np π^+ π^-$ was studied at the various momenta of incident neutrons. It was shown that the characteristics of the reaction at the momenta above 3 GeV/c could be described by the model of reggeized $π$ exchange (OPER). At the momenta below 3 GeV/c, it was necessary to use additionally the mechanism of one baryon exchange (OBE).
A method to extract the polarization of $Ω$ hyperons produced via the strong interaction is presented. Assuming they are spin 3/2 particles, the corresponding spin density matrix can be written in terms of seven non-zero polarization parameters, all retrievable from the angular distribution of the decay products. Moreover by considering the full decay chain $Ω\rightarrow ΛK\rightarrow pπK$ the magnitude of the asymmetry parameters $β_Ω$ and $γ_Ω$ can be obtained. This method, applied here to the specific $Ω$ case, can be generalized to any weakly decaying hyperon and is perfectly suited for th…
In this work, the role of the $Δ^{\ast }$ resonances in the process of $pp\rightarrow nK^{+}Σ^{+}$ are systematically investigated with the effective Lagrangian approach and the isobar model. We find that a $P_{31}$ state, either $Δ^{\ast }(1750)$ or $Δ^{\ast }(1910)$, is favored by the data while the $P_{33}$ state, namely $Δ^{\ast }(1920)$, has small contribution. Besides, either sub-threshold $S_{31}$ $Δ^{\ast }(1620)$ resonance or strong $nΣ$ final state interaction or both have possible contribution at near threshold region, depending on the measured cross sections. We demonstrate the inv…
Cross section of the neutron capture reaction $n+p\rightarrow d+γ$ at threshold was calculated with different realistic $^{3}S_{1}$ deuteron and $^{1}S_{0}$ $np$ scattering wave functions stemming from Nijmegen-II, JISP16, Paris, Idaho and Moscow (with forbidden states) potentials. It is found that this reaction with thermal neutrons may be described without a contribution of meson exchange currents.
The inclusive reactions $pp \rightarrow e^+ e^- X$ and $np \rightarrow e^+ e^- X$ at the laboratory kinetic energy of 1.25 GeV are investigated in a model of dominance of nucleon and $Δ$ resonances. Experimental data for these reactions have recently been reported by the HADES Collaboration. In the original model, the dileptons are produced either from the decays of nucleon and $Δ$ resonances $R \rightarrow N e^+ e^-$ or from the Dalitz decays of $π^0$- and $η$-mesons created in the $R \to Nπ^0$ and $R \to Nη$ decays. We found that the distribution of dilepton invariant masses in the $pp \righ…
The cross section for the reaction $dd\rightarrow \,^4\!H\!e\,η$ close to threshold is estimated in a two-step model, similar to that which successfully describes near-threshold $pd\rightarrow \,^3\!H\!e\,η$ production. A $π$-meson, created in a $dp\rightarrow \,^3\!H\!e\,π^o$ process on one nucleon in the target deuteron, is converted into an $η$-meson by a secondary $π^o n \to n\,η$ reaction on the other nucleon. The kinematics are such that both processes are nearly physical so that only small Fermi momenta are required. The predictions of the model are in good agreement with recent Saclay …
The long mean free path of $K^+$ mesons in nuclear matter makes this particle a suitable messenger for the dynamics of nucleus-nucleus reactions at intermediate energies (100 MeV to 3 GeV per nucleon). A prerequisite for this is the knowledge of the elementary production cross sections $πN \rightarrow ΣK$. Here these cross sections are studied for the first time with the explicite inclusion of the relevant baryon resonances up to 2 GeV as intermediate states. The baryon resonances -- $N(1710)\, I(J^P) = \frac{1}{2} (\frac{1}{2}^+),\, N(1720)\, \frac{1}{2} (\frac{3}{2}^+)$ and $Δ(1920)\, \frac{…
In this work, we make a theoretical study on the $p \bar p \rightarrow Λ\barΛη$ reaction for antiproton beam energy from threshold to 4GeV within an effective Lagrangian approach and isobar model. By assuming this reaction is dominated by the excitation of $Λ$ and $\bar Λ$ resonances in intermediate states, we calculate the total cross sections and give the predictions of the angular distribution and invariant mass spectrum of final particles. In particular, we discuss the possibility to verify the existence of a narrow $Λ$ resonance found in the process of $K^- p\to ηΛ$ in the present reactio…
By using resonance model, we investigate $K^+ N \rightarrow K N η$ reactions with the assumption that these reactions are dominated by the excitation of $N^*(1535)$ near threshold. It is found that the hyperon and $ρ$ exchange diagrams give the most important contributions to these reactions. Thus these reactions may be a good place to study the coupling of $N^*(1535)$ with $KΛ$, $KΣ$ and $Nρ$ channels. We demonstrate that the angular distributions of final particles provide useful information about the different mechanisms of the $N^*(1535)$ excitations, which could be useful for future exper…
We investigate the charmed baryon production reaction $p\bar{p}\rightarrowΛ_c\barΛ_c$ in an effective Lagrangian approach. Besides the $t$-channel $D^0$ and $D^{*0}$ mesons exchanges, the $s$-channel $Y(4630)$ meson exchange is taken into account. For the total cross sections, the $D^0$ and $D^{*0}$ mesons provide minor background contributions, while the $Y(4630)$ state gives a clear peak structure with the magnitude of 10 $μ$b at center of mass energy 4.63 GeV. Basing on the results, we suggest that the reaction of $p\bar{p}\rightarrowΛ_c\barΛ_c$ can be used to search for the $1^{--}$ charmo…
A simple partial wave amplitude analysis of $\overline{p}p \rightarrow K^-K^+$ has been performed for data in the range $p_{\rm lab}$ = 360 -- 1000 MeV/$c$. In this low momentum interval only partial wave amplitudes with $J$ equal to 0, 1 and 2 are needed to obtain a good fit to the experimental data. This maximal $J$ = 2 value is smaller than what is required for the data of the reaction $\overline{p}p \rightarrow π^-π^+$ in the same momentum interval.
The main features of nuclear reactions with participation of baryon resonances ($Δ$(1232), S(1535) and $Λ$(1405)), which are interpreted as a manifestation of the bound states of nucleus and corresponding meson are discussed.
The meson-baryon interaction in s-wave in the strangeness S=-1 sector has been studied, employing a chiral SU(3) Lagrangian up to next-to-leading order (NLO) and implementing unitarization in coupled channels. The parameters of the Lagrangian have been fitted to a large set of experimental data in different two-body channels, paying special attention to the $\bar{K} N \rightarrow K Ξ$ reaction, which is particularly sensitive to the NLO terms. With the aim of improving the model in the $KΞ$ production channels, effects of the high spin hyperon resonances $Σ(2030)$ and $Σ(2250)$ have been taken…
The $Λ(1405)$ resonance production reaction is investigated within the framework of the coupled-channels Alt-Grassberger-Sandhas (AGS) equations. We perform full three-body calculations for the $\bar{K}NN-πYN$ amplitudes on the physical real energy axis and investigate how the signature of the $Λ(1405)$ appears in the cross sections of the $K^-d\rightarrow πΣn$ reactions, also in view of the planned E31 experiment at J-PARC. Two types of meson-baryon interaction models are considered: an energy-dependent interaction based on chiral $SU(3)$ effective field theory, and an energy-independent vers…
We perform a momentum-space calculation of the reaction $pp \rightarrow ppπ^0$ near threshold. Direct production and pion rescattering are taken into account. For the latter a T-matrix obtained from a microscopic model of the $πN$ interaction is employed. The effects of some approximations commonly used in studies of $ pp \rightarrow ppπ^0$ \ are discussed. We find that those approximations overestimate the cross section and also modify its energy dependence. We obtain a significant contribution from rescattering, but not nearly enough to describe the data.
Collective reaction paths for fusion reactions, $^{16}$O+$α$ $\rightarrow$ $^{20}$Ne and $^{16}$O+$^{16}$O $\rightarrow$ $^{32}$S, are microscopically determined, on the basis of the adiabatic self-consistent collective coordinate (ASCC) method. The collective path is maximally decoupled from other intrinsic degrees of freedom. The reaction paths turn out to deviate from those obtained with standard mean-field calculations with constraints on quadrupole and octupole moments. The potentials and inertial masses defined in the ASCC method are calculated along the reaction paths. The sub-barrier f…
We study the production of $K^+, ρ, ω$ and $ϕ$ mesons in $p + ^{12}C$ reactions on the basis of empirical spectral functions. The high momentum, high removal energy part of the spectral function is found to be negligible in all cases close to the absolute threshold. Furthermore, the two-step process ($pN \rightarrow πN N; πN \rightarrow N + K^+, ρ, ω, ϕ$) dominates the cross section at threshold energies in line with earlier calculations based on the folding model.
The lowest-lying resonance in the QCD spectrum is the $0^{++}$ isoscalar $σ$ meson, also known as the $f_0(500)$. We augment SU(2) chiral perturbation theory ($χ$PT) by including the $σ$ meson as an additional explicit degree of freedom, as proposed by Soto, Talavera, and Tarrús and others. In this effective field theory, denoted $χ$PT$_S$, the $σ$ meson's well-established mass and decay width are not sufficient to properly renormalize its self energy. At $\mathcal{O}(p^4)$ another low-energy constant appears in the dressed $σ$-meson propagator; we adjust it so that the isoscalar pion-pion sca…
The isoscalar-isovector ($ρ-ω$) interferences in the exclusive reactions $π^- p \to n e^+ e^-$ and $π^+ n \to p e^+ e^-$ near the $ω$ threshold leads to a distinct difference of the dielectron invariant mass distributions depending on beam energy. The strength of this effect is determined by the coupling of resonances to the nucleon vector-meson channels and other resonance properties. Therefore, a combined analysis of these reactions can be used as a tool for determining the baryon resonance dynamics.
To facilitate the relativistic heavy-ion calculations based on transport equations, the binary collisions involving a $Δ$ resonance in either the entrance channel or the exit channel are investigated within a Hamiltonian formulation of $πNN$ interactions. An averaging procedure is developed to define a quasi-particle $Δ^*$ and to express the experimentally measured $NN\rightarrow πNN$ cross section in terms of an effective $NN\rightarrow NΔ^\ast$ cross section. In contrast to previous works, the main feature of the present approach is that the mass and the momentum of the produced $Δ^*$'s are …
New measurement by CELSIUS-WASA Collaboration on the pp->pn pi+ reaction reveals clear evidence for the presence of the Roper resonance N*(1440) which has been ignored in previous theoretical calculations. In this article, based on an effective Lagrangian approach and available knowledge on the Roper resonance, we investigate the role of the Roper resonance for the pp->pn pi+ reaction. It is found that the contribution from the Roper resonance N*(1440) becomes significant for kinetic energy above 1.1 GeV, consistent with the new experimental observation. The t-channel sigma-meson exchange is d…
By using an effective Lagrangian method, we study the effects of a newly proposed $Σ^*(1/2^-)$ state with mass around 1380 MeV in the initial-state polarized $γN\rightarrow K^{+} Σ^*(1385) \rightarrow K^{+} πΛ$ process near threshold. The theoretical predictions for the helicity cross sections $σ_{3/2}$, $σ_{1/2}$ as well as their ratios, and the angular distributions of $π$ in the $πΛ$ center-of-mass system are given. It is found that assuming $Σ^*(1/2^-)$ exists or not, these physical quantities are distinctly different. So our results could be useful for the investigation of the existence o…
The reaction $e^+e^-\rightarrow Λ^+_c\barΛ^-_c$ is investigated at energies close to the threshold with emphasis on the role played by the $X(4630)$ resonance. The interaction in the final $Λ^+_c \barΛ^-_c$ system, constructed within chiral effective field theory and supplemented by a pole diagram that represents a bare $X(4630)$ resonance, is taken into account rigorously. The pole parameters of the $X(4630)$ are extracted and found to be compatible with the ones of the $X(4660)$ resonance that have been established in the reaction $e^+e^- \to π^+π^-ψ(2S)$. The actual result for the $X(4630)$…
We present an approximate analytic expression for thermonuclear reaction rate of charged particles when the cross section contains a single narrow or wide resonance described by a Breit-Wigner shape. The resulting expression is uniformly valid as the effective energy and resonance energy coalesce. We use our expressions to calculate the reaction rate for $^{12}$C(p,$γ$)$^{13}$N.
The rho - omega interference in the exclusive reaction pi N \to N' e+ e- is studied within a schematic model including the established baryon resonances up to 1720 MeV. Near threshold the interference can be used to separate the isoscalar part of the electromagnetic current. The role of various baryon resonances is highlighted.
We present a brief overview of recent developments in ab initio calculations of nuclear scattering and reactions with a focus on applications of the no-core shell model with continuum method.
Photo disintegration of the deuteron and photo pionproduction on the deuteron are described in the region of the $Δ$-resonance. The two reactions are unitarily coupled. A novel definition of electromagnetic exchange currents in the presence of pionproduction is given. Numerical predictions are done for spin-independent and spin-dependent observables of both reactions. The sensitivity of the results with respect to the nucleon-$Δ$ transition current and with respect to the irreducible nucleon-$Δ$ potential is studied.
Based on the effective Lagrangian approach, the $ J/ψ\to p \bar{p} ϕ$ decay is studied in an isobar resonance model with the assumption that the $ϕ$-meson is produced from intermediate nucleon resonances. The contributions from the $N^*_{1/2^-}(1535)$, $N^*_{3/2^+}(1900)$, $N^*_{1/2^-}(2090)$ and $N^*_{1/2^+}(2100)$ states are considered. In terms of the coupling constants $g^{2}_{ϕN N^{*}}$ and $g^{2}_{ϕN N^{*}}$ extracted from the data of the partial decay widths of the $N^*$s to the $Nπ$ channel, the reaction cross section of the $π^{-}p\rightarrow nϕ$ process and the partial decay widths o…
The X(2265) resonance was previously observed in DISTO data of p+p rightarrow p+Lambda+K+ at 2.85 GeV on an attempt of searching for the kaonic nuclear state K-pp rightarrow p + Lambda. In the present paper we report an additional finding, namely, a double resonance type phenomena, not only with a peak at M(pLambda) = 2265 MeV/c2 but also a broad bump at M(K+ Lambda) ~ 1700 MeV/c2. This "double-resonance" zone is expressed as XY(2265, 1700). The latter bump may result from nearby nucleon resonances, typically N*(1710), as well as by attractive K - Lambda final-state interaction. We point out t…
We study antiproton-proton annihilation at rest into $πϕ$ and $γϕ$. Rescattering by $\overline{K^*}K+K^*\overline{K}$ and $ρ^{+}ρ^{-}$ for $\overline{p}p\rightarrowπϕ$ states is sizable, of order $(0.90\, {\rm to}\,2.6)\times 10^{-4}$ in the branching ratio, but smaller than experiment. For $\overline{p}p\rightarrowγϕ$ the rescattering contributions are negligible, but the $γϕ$ channel is well explained by a $ρϕ$ intermediate state combined with vector meson dominance.
An effective Hamiltonian consisting of bare $Δ\leftrightarrowπN$, $γN$ vertex interactions and energy-independent meson-exchange $πN \leftrightarrow πN, γN$ transition operators is derived by applying a unitary transformation to a model Lagrangian with $N,Δ,π$, $ρ$, $ω$, and $γ$ fields. With appropraite phenomenological form factors and coupling constants for $ρ$ and $Δ$, the model can give a good description of $πN$ scattering phase shifts up to the $Δ$ excitation energy region. It is shown that the best reproduction of the recent LEGS data of the photon-asymmetry ratios in $γp \rightarrow π^…
It is shown that most of the models for analyzing meson-baryon reactions in the nucleon resonance region can be derived from a Hamiltonian formulation of the problem. An extension of the coupled-channel approach to include $ππN$ channel is briefly described and some preliminary results for the $N^*(1535)$ excitation are presented.
The expressions for the differential cross section and of the polarization observables for the reaction $\bar p+p\rightarrow e^++e^-$ are given in terms of the nucleon electromagnetic form factors in the laboratory system. Radiative corrections due to the emission of virtual and real soft photons from the leptons are also calculated. Unlike the center-of- mass system case, they depend on the scattering angle. Polarization effects are derived in the case when the antiproton beam, the target and the electron in the final state are polarized. Numerical estimations have been done for all observabl…
The cross-sections of the $γp-γ' N'$, $γp-π' N'$ and $γp-γ'π' N'$ reactions are calculated in the framework of the field-theoretical one-particle ($π,ω,ρ$-mesons, nucleon and $Δ$-resonance) exchange model. Unlike the other relativistic approaches, our resulting amplitudes of the $γp$ multichannel reactions require one-variable covariant vertex functions as input ingredient and every diagram of these amplitudes satisfies the current conservation condition in the Coulomb gauge. The complete set of the model independent skeleton diagrams for the $γ p\toγ'π'N'$ reaction is presented. The separable…
Reliable estimates of neutrino-nucleus reactions in the resonance-excitation region play an important role in many of the on-going and planned neutrino oscillation experiments. We study here neutrino-nucleus reactions in the delta-particle excitation region with the use of neutrino pion-production amplitudes calculated in a formalism in which the resonance contributions and the background amplitudes are treated on the same footing. Our approach leads to the neutrino-nucleus reaction cross sections that are significantly different from those obtained in the conventional approach wherein only th…
We report on the first results of a full three-body calculation of the $\bar{K}NN$-$πYN$ amplitude for the $K^-d\rightarrowπΣn$ reaction, and examine how the $Λ(1405)$ resonance manifests itself in the neutron energy distributions of $K^-d\rightarrowπΣn$ reactions. The amplitudes are computed using the $\bar{K}NN$-$πYN$ coupled-channels Alt-Grassberger-Sandhas (AGS) equations. Two types of models are considered for the two-body meson-baryon interactions: an energy-independent interaction and an energy-dependent one, both derived from the leading order chiral SU(3) Lagrangian. These two models …
We investigate the two-body reactions $\bar K N\rightarrow \bar K N$, $\bar K N\rightarrow πΛ$, and $\bar K N\rightarrow πΣ$ via single-energy partial-wave analyses in the c.m.\ energy range 1480 to 2100 MeV. The partial-wave amplitudes for these reactions thus extracted were constrained by a multichannel energy-dependent model satisfying unitarity of the partial-wave $S$-matrix. We obtain excellent predictions of differential cross sections, polarizations, polarized cross sections, and cross sections for these reactions from a global energy-dependent solution.
Parametrizations of total cross sections sufficient for all channels of the $πB \rightarrow Y K$ reactions are completed using a resonance model. As well as discussing the $πN \rightarrow ΛK$ reactions, which were not presented in our previous publications, we present the differential cross section for $πN \rightarrow ΛK$. This report also aims at presenting supplementary discussions to our previous work.
We study the reactions $γγ\rightarrow π^0π^0$, $π^+π^-$, $K^0\bar{K}^0$, $K^+K^-$, $ηη$ and $π^0η$ based on a chiral Lagrangian with dynamical light vector mesons as formulated within the hadrogenesis conjecture. At present our chiral Lagrangian contains 5 unknown parameters that are relevant for the photon fusion reactions. They parameterize the strength of interaction terms involving two vector meson fields. These parameters are fitted to photon fusion data $γγ\rightarrow π^0π^0$, $π^+π^-, π^0η$ and to the decay $η\rightarrowπ^0γγ$. In order to derive gauge invariant reaction amplitudes in t…
We report on the calculation of first-order QED corrections for the $γp\rightarrow l^+l^-p^{\prime}$ process. An upcoming experiment at MAMI (Mainz) aims to compare the cross sections of muon- and electron-pair production in this reaction to test lepton universality. Precise knowledge of the electromagnetic radiative corrections is needed for these measurements. As a first step, we present the leading QED radiative corrections in the soft-photon approximation when accounting for the finite lepton mass. For the kinematics at MAMI, we find corrections of the percent level for muons, and of order…
A combined study of the reactions $K^-p\rightarrow Σ^0π^0$, $Λπ^0$ and $\bar{K}^0n$ at low energies is carried out with a chiral quark-model approach. Good descriptions of the experimental observations are obtained. The roles of the low-lying strangeness $S=-1$ hyperon resonances in these processes are carefully analyzed. We find that: (i) In the $K^-p\rightarrow Σ^0π^0$ process, both $Λ(1405)S_{01}$ and $Λ(1520)D_{03}$ play dominant roles. Significant contributions of $Λ(1670)S_{01}$ and $Λ(1690)D_{03}$ could be seen around their threshold; (ii) In the $K^-p\rightarrow Λπ^0$ process, some obv…
In this paper, we study the polarization of the $Λ(1405)$ in the $γp \rightarrow K^+ πΣ$ reaction within an effective Lagrangian approach and isobar model. In our model, the $Λ(1405)$ is excited through the t-channel $K/K^*$ exchanges and u-channel hyperon exchange. Compared to previous studies, we also include the contribution from a contact term, which is necessary for our model to interpret the polarization of the $Λ(1405)$. In addition, we also discuss the possibility to verify the proposed two-pole structure of the $Λ(1405)$ using the polarization data. We find that the polarization of th…
We report on a theoretical study of the $K^- p \to ηΛ$ reaction near threshold by using an effective Lagrangian approach. The role of $s-$channel $Λ(1670)$, $t-$channel $K^*$ and $u-$channel proton pole diagrams are considered. We show that the total cross sections data are well reproduced. However, only including the $s-$wave $Λ(1670)$ state and the background contribution from $t-$ and $u-$channel are not enough to describe the bowl structures in the angular distribution of $K^- p \to ηΛ$ reaction, which indicates that there should be higher partial waves contributing to this reaction in som…
The $η$ mesic nucleus is considered to be one of the interesting exotic many body systems and has been studied since 1980's theoretically and experimentally. Recently, the formation of the $η$ mesic nucleus in the fusion reactions of the light nuclei such as $d + d \rightarrow (η+ α) \rightarrow X$ has been proposed and the experiments have been performed by WASA-at-COSY. We develop a theoretical model to evaluate the formation rate of the $η$ mesic nucleus in the fusion reactions and show the calculated results. We find that the $η$ bound states could be observed in the reactions in cases wit…
Within the multiple scattering formulation, the incoherent pion production in neutrino-deuteron reactions at energies near the $Δ(1232)$ resonance is investigated. The calculations include an impulse term and one-loop contributions from nucleon-nucleon ($NN$) and pion-nucleon ($πN$) final state interactions. The input amplitudes of $πN$ scattering and electroweak pion production reaction on nucleon are generated from a dynamical model which describes very extensive data of $πN$ scattering and both the electromagnetic and the weak pion production reactions on the nucleon. The $NN$ scattering am…
We present a new reaction, complementary to the $J/ψ\rightarrow ηK^{*0}\bar{K}^{*0}$ from which an $h_1$ resonance with mass around $1830$ MeV was reported from a BESIII experiment. The new reaction is $η_c\rightarrow ϕK^*\bar{K}^*$, or $η_c(2S)\rightarrow ϕK^*\bar{K}^*$. Using the information from the analysis of $J/ψ\rightarrow ηK^{*0}\bar{K}^{*0}$, we find that the $K^*\bar{K}^*$ invariant mass distribution for those two $η_c$ decays exhibits a clear peak around $1830$ MeV perfectly distinguishable from what one obtains with pure phase space. We suggest the implementation of these reactions…
The determination of the Argonne National Laboratory-Osaka University (ANL-Osaka) Partial-Wave Amplitudes (PWA) of $πN$ and $γN$ Reactions is reviewed. The predicted PWA are presented on a web page (https://www.phy.anl.gov/theory/research/anl-osaka-pwa). The formulas are given for using the predicted PWA to calculate the cross sections of (1) meson-baryon ($MB$) scattering $MB \rightarrow M'B'$ with $MB, M'B'= πN, ηN, KΛ, KΣ$, (2) two-pion production $πN \rightarrow πΔ, ρN, σN \rightarrow ππN$, (3) Meson photoproduction $γN \rightarrow πN, ηN, KΛ, KΣ$, (4) Pion electroproduction $N(e,e'π)N$, (…
For the study of the $Σ$ resonances, we analyze the differential cross sections and $Λ$ polarizations for the reactions $K^-n\toπ^-Λ$ and $K^-p\toπ^0Λ$ with an effective Lagrangian approach. Data of an early experiment and the recent Crystal Ball experiment at BNL are included in the analysis with the c.m. energy from 1550 to 1676 MeV. Our results clearly support the existence of a $Σ$ resonance with $J^P={1\over 2}^+$, mass near 1633 MeV, and width about 120 MeV, which confirms the 3-star $Σ(1660) 1/2^+$ in PDG. Meanwhile, our results do not support the existence of the 2-star $Σ(1620){1\over…
A combined analysis of the reactions $π^-p\rightarrow K^0Λ$ and $ηn$ is carried out with a chiral quark model. The data in the center-of-mass (c.m.) energy range from threshold up to $W\simeq 1.8$ GeV are reasonably described. For $π^-p\rightarrow K^0Λ$, it is found that $N(1535)S_{11}$ and $N(1650)S_{11}$ paly crucial roles near threshold. The $N(1650)S_{11}$ resonance contributes to the reaction through configuration mixing with $N(1535)S_{11}$. The constructive interference between $N(1535)S_{11}$ and $N(1650)S_{11}$ is responsible for the peak structure around threshold in the total cross …
The reaction $K^-p\rightarrowΛη$ at low energies is studied with a chiral quark model approach. Good descriptions of the existing experimental data are obtained. It is found that $Λ(1670)$ dominates the reaction around threshold. Furthermore, $u$- and $t$-channel backgrounds play crucial roles in this reaction as well. The contributions from the $D$-wave state $Λ(1690)$ are negligibly small for its tiny coupling to $ηΛ$. To understand the strong coupling properties of the low-lying negative parity $Λ$ resonances extracted from the $\bar{K}N$ scattering, we further study their strong decays. It…
The few available data for the reactions $γp \rightarrow K^{0} Σ^{+}$ and $γn \rightarrow K^{+} Σ^{-}$ are compared to models developed for the processes $γp \rightarrow K^{+} Σ^{0}$ and $γp \rightarrow K^{+} Λ$. It is found that some of these phenomenological models overpredict the measurements by up to a factor of 100. Fitting the data for all of these reactions leads to drastically reduced Born coupling constants.
Inspired by the observation of the pentaquark states $P_{c}(4312),P_{c}(4440)$ and $P_{c}(4457)$ at LHCb, photoproduction of these three $P_{c}$ states via the interaction $γp\rightarrow J/ψp$ is investigated in an effective Lagrangian approach. The $t$-channel Pomeron exchange diffractive process is considered as the main background for the $J/ψ$ photoproduction. The numerical results show that the theoretical cross section, which is calculated by assuming a branching ratio $Br[P_{c}\rightarrow J/ψp]\simeq 3\%$, is consistent with the existing experimental data of the $ γp\rightarrow J/ψp$ pr…
