The energy spectra of light-mass kaonic nuclei were investigated using the theoretical framework of the $0s$-orbital model with zero-range $\bar{K} N$ and $\bar{K}\bar{K}$ interactions of effective single-channel real potentials. The energies of the $\bar{K} NN$, $\bar{K} NNN$, $\bar{K} NNNN$, $\bar{K}\bar{K} N$, and $\bar{K}\bar{K} NN$ systems were calculated in the cases of weak- and deep-binding of the $\bar{K} N$ interaction, which was adjusted to fit the $Λ(1405)$ mass with the energy of the $\bar{K} N$ bound state. The results qualitatively reproduced the energy systematics of kaonic nuclei calculated via other theoretical approaches. In the energy spectra of the $\bar{K} NN$ and $\bar{K}\bar{K} NN$ systems, the lowest states $\bar{K} NN(J^π,T=0^-,1/2)$ and $\bar{K}\bar{K} NN(0^+,0)$ were found to have binding energies approximately twice and four times as large as that of the $\bar{K} N(1/2^-,0)$ state, respectively. Higher $(J^π,T)$ states including $\bar{K} NN(1^-,1/2)$, $\bar{K}\bar{K} NN(0^+,1)$, and $\bar{K}\bar{K} NN(1^+,1)$ were predicted at energies of 9--25 MeV below the antikaon-decay threshold. The effective $Λ(1405)$-$Λ(1405)$ interaction in the $\bar{K}\bar{K} N N$ system was also investigated via a $\bar{K} N+\bar{K} N$-cluster model. Strong and weak $Λ(1405)$-$Λ(1405)$ attractions were obtained in the $S^π=0^+$ and $S^π=1^-$ channels, respectively. The $Λ(1405)$-$Λ(1405)$ interaction in the $$\bar{K}\bar{K} NN$ system was compared with the effective $d$-$d$ interaction in the $NNNN$ system, and the properties of dimer-dimer interactions in hadron and nuclear systems were discussed.
A new evaluation of the $1s$ level shift and width of kaonic deuterium is presented based on an accurate $\bar{K}NN$ three-body calculation, using as input a realistic antikaon-nucleon interaction constrained by the SIDDHARTA kaonic hydrogen data. The three-body Schrödinger equation is solved with a superposition of a large number of correlated Gaussian basis functions extending over distance scales up to several hundred fm. The resulting energy shift and width of the kaonic deuterium $1s$ level are $E\simeq 0.67$ keV and $Γ\simeq 1.02$ keV, with estimated uncertainties at the 10% level.
A chirally-motivated coupled-channel $\bar{K}N$ potential, reproducing all low-energy experimental data on $K^- p$ scattering and kaonic hydrogen and suitable for using in accurate few-body calculations, was constructed. The potential was used for calculations of low-energy amplitudes of the elastic $K^- d$ scattering using Faddeev-type AGS equations with coupled $\bar{K}NN$ and $πΣN$ channels. A complex $K^- - d$ potential reproducing the three-body $K^- d$ amplitudes was constructed and used for calculation of $1s$ level shift and width of kaonic deuterium. The predicted shift $ΔE_{1s}^{K^- …
Correct treatment of subthreshold Kbar-N dynamics is mandatory in kaonic-atom and Kbar-nuclear bound-state calculations, as demonstrated by using in-medium chirally-based models of Kbar-N interactions. Recent studies of kaonic-atom data reveal appreciable multi-nucleon contributions. Kbar-nuclear widths larger than 50 MeV are anticipated.
Non-mesonic decay of kaonic nuclei is investigated under a Lambda(1405) doorway picture where the Kbar absorptions in nuclei take place through the Lambda(1405) resonance. Calculating Lambda(1405) N to YN transitions in one-meson exchange, we find that the non-mesonic decay ratio Gamma_{Lambda N} / Gamma_{Sigma^{0} N} depends strongly on the ratio of the couplings Lambda(1405)-Kbar N and Lambda(1405)-pi Sigma. Especially a larger Lambda(1405)-Kbar N coupling leads to enhancement of the decay to Lambda N. Using the chiral unitary approach for description of the Kbar N amplitudes, we obtain Gamm…
Using a microscopic antikaon-nucleus optical potential recently developed by Ramos and Oset (nucl-th/9906016, in print in Nuclear Physics A) from a chiral model, we calculate strong interaction shifts and widths for $K^-$ atoms. This purely theoretical potential gives an acceptable description of the measured data ($χ^2/{\rm num.data}= 3.8$), though it turns out to be less attractive than what can be inferred from the existing kaon atomic data. We also use a modified potential, obtained by adding to the latter theoretical one a s-wave term which is fitted to known experimental kaonic data ($χ^…
The present status of the Lambda(1405) structure study in chiral dynamics is briefly reviewed. It turns out that the Lambda(1405) resonance can be described by hadronic dynamics. The idea of the hadronic molecular state is extended to kaonic few-body states. It is concluded that, due to the fact that K and N have similar coupling nature in s-wave Kbar couplings, there are few-body quasibound states with kaons systematically just below the break-up thresholds, like KbarNN, KbarKN and KbarKK, as well as Lambda(1405) as a KbarN quasibound state and f_0(980) and a_0(980) as KbarK.
Lambda*=Lambda(1405) plays an essential role in forming kaonic nuclear clusters (KNC). The simplest KNC, K-pp, has the structure Lambda*p=(K-p){I=0}p, where a real kaon migrates between two nucleons, mediating super-strong Lambda*-p$ attraction. Production data of K-pp have been accumulated by DISTO, J-PARC E27 and J-PARC E15 experiments. In the case of K-K-pp, the attractive covalent bond of Lambda*Lambda* is doubly enhanced compared to the Lambda*-p one. As a consequence, a m-th Lambda* multiplet, (Lambda*)m, with m(m-1)/2 bonds becomes more stable than its corresponding neutron aggregate, (…
We calculate $K^-$-nucleus elastic differential, reaction and total cross sections for different nuclei ($^{12}$C,$^{40}$Ca and $^{208}$Pb) at several laboratory antikaon momenta, ranging from 127 MeV to 800 MeV. We use different antikaon-nucleus optical potentials, some of them fitted to kaonic atom data, and study the sensitivity of the cross sections to the considered antikaon-nucleus dynamics.
Motivated by the precise measurement of the $1S$ level shift of kaonic hydrogen, we perform accurate three-body calculations for the spectrum of kaonic deuterium using a realistic antikaon-nucleon ($KN$) interaction. In order to describe both short- and long-range behavior of the kaonic atomic states, we solve the three-body Schrödinger equation with a superposition of a large number of correlated Gaussian basis functions covering distances up to several hundreds of fm. Transition energies between $1S$, $2P$ and $2S$ states are determined with high precision. The complex energy shift of the $1…
The role played by subthreshold meson-baryon dynamics is demonstrated in kaonic-atom, Kbar-nuclear and eta-nuclear bound-state calculations within in-medium models of Kbar-N and eta-N interactions. New analyses of kaonic atom data reveal appreciable multi-nucleon contributions. Calculations of eta-nuclear bound states show, in particular, that the eta-N scattering length is not a useful indicator of whether or not eta mesons bind in nuclei nor of the widths anticipated for such states.
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 686-8…
Properties of multi-antikaonic nuclei (MKN), where several numbers of $K^-$ mesons are bound, are studied in the relativistic mean-field model, combined with chiral dynamics for kaonic part of the thermodynamic potential. The density profiles for nucleons and $K^-$ mesons, the single particle energy of the $K^-$ mesons, and binding energy of the MKN are obtained. The effects of the $\bar K-\bar K$ interactions on these quantities are discussed in comparison with other meson ($σ$, $ω$, and $ρ$)-exchange models. It is shown that the $\bar K-\bar K$ interactions originate from two contributions: …
A sensitive correlation between the ground-state properties of light kaonic nuclei and the symmetry energy at high densities is constructed under the framework of relativistic mean-field theory. Taking oxygen isotopes as an example, we see that a high-density core is produced in kaonic oxygen nuclei, due to the strongly attractive antikaon-nucleon interaction. It is found that the $1S_{1/2}$ state energy in the high-density core of kaonic nuclei can directly probe the variation of the symmetry energy at supranormal nuclear density, and a sensitive correlation between the neutron skin thickness…
We evaluate the antikaon and hyperon spectral functions in a self-consistent and covariant many-body approach. The computation is based on coupled-channel dynamics derived from the chiral SU(3) Lagrangian. A novel subtraction scheme is developed that avoids kinematical singularities and medium-induced power divergencies all together. Scalar and vector mean fields are used to model nuclear binding and saturation. The effect of the latter is striking for the antikaon spectral function that becomes significantly more narrow at small momenta. Attractive mass shifts of about 30 and 40 MeV are predi…
We overview the recent progress in the investigation of the antikaon dynamics with single nucleon and with few-body nuclei, based on chiral SU(3) symmetry. We first show how the Lambda(1405) resonance emerges from the coupled-channel Kbar N-pi Sigma interaction. Next, we present the construction of an up-to-date Kbar N interaction in response to the recent measurement of kaonic hydrogen. Finally, we discuss the possibility of the antikaon bound states in nuclei from the perspective of few-body physics.
We have studied the structure of K- pp comprehensively by solving this three-body system in a variational method, starting from the Ansatz that the Lambda(1405) resonance (~ Lambda*) is a K-p bound state. The structure of K-pp reveals a molecular feature, namely, the K- in Lambda* as an "atomic center" plays a key role in producing strong covalent bonding with the other proton. We point out that strongly bound Kbar nuclear systems are formed by ``super strong" nuclear force due to migrating real bosonic particles Kbar a la Heitler-London-Heisenberg, whereas the normal nuclear force is caused b…
The properties of the Lambda(1405) resonance are key ingredients for determining the antikaon-nucleon interaction in strangeness nuclear physics, and the novel internal structure of the Lambda(1405) is of great interest in hadron physics, as a prototype case of a baryon that does not fit into the simple three-quark picture. We show that a quantitative description of the antikaon-nucleon interaction with the Lambda(1405) is achieved in the framework of chiral SU(3) dynamics, with the help of recent experimental progress. Further constraints on the Kbar N subthreshold interaction are provided by…
We critically revise the recent claims of narrow deeply bound kaonic states and show that at present there is no convincing experimental evidence for their existence. In particular, we discuss in details the claim of K- pp deeply bound state associated to a peak seen in the Lambda p invariant mass spectrum from K- nuclear absorption reactions by the FINUDA collaboration. An explicit theoretical simulation shows that the peak is simply generated from a two-nucleon absorption process, like K- pp --> Lambda p, followed by final-state interactions of the produced particles with the residual nucleu…
The in-medium mass and energy of kaons and antikaons are studied within the Relativistic Mean Field approach and compared with predictions from chiral models by taking care of kaon-nucleon scattering data. Implications for the subthreshold production of kaons and antikaons in heavy-ion collisions are discussed. We find only small corrections due to in-medium effects on the mean-field level for the relevant production processes for kaons. The production of kaons is even less favourable at high density due to repulsive vector interactions. We conclude that one has to go beyond mean-field approac…
Based on our Faddeev-Yakubowsky calculations of four-body kaonic nuclear systems it was revealed that the structure of K-K-pp is well approximated by two Lambda*=K-p's with strong mutual attraction. It is vitally important to study this nucleus, as it is an essential gateway toward multi-Lambda* nuclei. Two experimental proposals are presented: i) production of K-K-pp by p+p reactions at T_p = 7 GeV, and ii) search for K-K-pp from the invariant mass of M(Lambda-Lambda) around 2.6 GeV/c2 in high-energy HI reactions.
We perform a combined analysis of antikaon-nucleon scattering cross sections and the recent SIDDHARTA kaonic hydrogen data in the framework of a coupled-channel Bethe-Salpeter approach at next-to-leading order in the chiral expansion of the effective potential. We find a precise description of the antikaon-proton scattering amplitudes and are able to extract accurate values of the scattering lengths, a0=-1.81^+0.30_-0.28 + i 0.92^+0.29_-0.23 fm, a1=+0.48^+0.12_-0.11 + i 0.87^+0.26_-0.20 fm. We also discuss the two-pole structure of the Lambda(1405).
Low energy \bar{K}N interactions are studied within Unitary Chiral Perturbation Theory at next-to-leading order with ten coupled channels. We pay special attention to the recent precise determination of the strong shift and width of the kaonic hydrogen 1s state by the DEAR Collaboration that has challenged our theoretical understanding of this sector of strong interactions. We typically find two classes of solutions, both of them reproducing previous data, that either can or cannot accommodate the DEAR measurements. The former class has not been previously discussed.
For almost 50 years the structure of the Lambda(1405) resonance has been a mystery. Even though it contains a heavy strange quark and has odd parity, its mass is lower than any other excited spin-1/2 baryon. Dalitz and co-workers speculated that it might be a molecular state of an antikaon bound to a nucleon. However, a standard quark-model structure is also admissible. Although the intervening years have seen considerable effort, there has been no convincing resolution. Here we present a new lattice QCD simulation showing that the strange magnetic form factor of the Lambda(1405) vanishes, sig…
$\bar{K}$-nucleon interactions are investigated in the framework of coupled-channels dynamics based on the next-to-leading order chiral SU(3) meson-baryon effective Lagrangian. A recent determination of the 1s shift and width of kaonic hydrogen enables us to set accurate constraints on the coupled-channels meson-baryon amplitudes in the strangeness $S=-1$ sector. Theoretical uncertainties in the subthreshold extrapolation of the coupled-channels amplitudes are discussed. Using this framework, we give predictions for $K^-$-neutron interactions and for the spectrum of the $Λ(1405)$ resonance. A …
Using a gauged flavor SU(3) invariant hadronic Lagrangian, we study $Ξ$ production from $\bar K$ induced reactions on $Λ$ and $Σ$ in a coupled-channel approach. Including the four channels of $\bar KΛ$, $\bar KΣ$, $πΞ$, and $ηΞ$, we solve the Bethe-Salpeter equation in the $K$-matrix approximation by neglecting the off-shell contribution in the intermediate states. For the transition potential which drives the higher-order contribution, we consider all allowed Born diagrams in the $s$, $t$, and $u$ channels. With coupling constants determined from the SU(3) symmetry with empirical input, we fi…
The strong interaction between an antikaon and a nucleon is at the origin of various interesting phenomena in kaon-nuclear systems. In particular, the interaction in the isospin $I=0$ channel is sufficiently attractive to generate a quasi-bound state, the $Λ(1405)$ resonance, below the $\bar{K}N$ threshold. Based on this picture, it may be expected that the $\bar{K}N$ interaction also generates quasi-bound states in kaon-nuclear systems, sometimes called kaonic nuclei. At the same time, the $\bar{K}N$ quasi-bound picture of the $Λ(1405)$ is also related to the discussion of hadronic molecules …
Recent developments are summarised concerning low-energy KbarN interactions as they relate to the possible existence of antikaon-nuclear quasibound states. An exploratory study of antikaons bound to finite nuclei is performed, with emphasis on the evolution of such states from light to heavy nuclei (A = 16 - 208). The energy dependent, driving attractive KbarN interactions are constructed using the s-wave coupled-channel amplitudes involving the Lambda(1405) and resulting from chiral SU(3) dynamics, plus p-wave amplitudes dominated by the Sigma(1385). Effects of Pauli and short-range correlati…
A recent successful observation of a dense and deeply bound \bar{K} nuclear system, K^-pp, in the p + p \rightarrow K^+ + K^-pp reaction in a DISTO experiment indicates that the double-\bar{K} dibaryon, K^-K^-pp, which was predicted to be a dense nuclear system, can also be formed in p+p collisions. We find theoretically that the K^- -K^- repulsion plays no significant role in reducing the density and binding energy of K^-K^-pp and that, when two Λ(1405) resonances are produced simultaneously in a short-range p+p collision, they act as doorways to copious formation of K^-K^-pp, if and only if …
Analyses of comprehensive sets of strong-interaction data consisting of level shifts, widths and yields in strange atoms of K mesons and Sigma hyperons are reviewed. The introduction of density dependent optical potentials, in both cases, improves significantly the fit to the data. A strongly attractive antikaon-nuclear potential of order 150-200 MeV in nuclear matter is suggested by fits to the kaonic-atom data, with interesting possible repercussions on kaon condensation and on the evolution of strangeness in high-density stars. The case for relatively narrow, deeply bound antikaon atomic st…
Recent developments and pending issues in low-energy strong interaction physics with strangeness are summarized. Chiral SU(3) effective field theory has progressed as the appropriate theoretical framework applied to antikaon- and hyperon-nuclear systems. Topics include antikaon-nucleon interactions and the Lambda(1405), KbarNN systems, recent developments in hyperon-nucleon interactions and strangeness in dense baryonic matter with emphasis on new constraints from neutron star observations.
The state of the art in the study of pionic, kaonic and Sigmionic atoms, along with the in-medium nuclear interactions deduced for these hadrons, is reviewed. A special emphasis is placed on recent developments in antikaon-nuclear physics, where a strongly attractive density dependent antikaon-nuclear potential of order 150-200 MeV in nuclear matter emerges by fitting K^- atom data. This has interesting repercussions on antikaon quasibound nuclear states, on the composition of strange hadronic matter and on kaon condensation in self bound hadronic systems.
We analyse the properties of the kaonic nuclear cluster (KNC) anti-KNN with the structure Nx(anti-KN)_(I = 0), having the quantum numbers I(J^P) = 1/2(0^-), and treated as a quasi-bound hadronic molecule state. We describe the properties of the hadronic molecule, or the KNC Nx(anti-KN)_(I = 0), in terms of vibrational degrees of freedom with oscillator wave functions and chiral dynamics. These wave functions, having the meaning of trial wave functions of variational calculations, are parameterised by the frequency of oscillations of the (anti-KN)_(I = 0) pair, which is fixed in terms of the bi…
We study kaonic hydrogen, the bound K^-p state A_(Kp). Within a quantum field theoretic and relativistic covariant approach we derive the energy level displacement of the ground state of kaonic hydrogen in terms of the amplitude of K^-p scattering for arbitrary relative momenta. The amplitude of low-energy K^-p scattering near threshold is defined by the contributions of three resonances Lambda(1405), Lambda(1800) and Sigma^0(1750) and a smooth elastic background. The amplitudes of inelastic channels of low-energy K^-p scattering fit experimental data on near threshold behaviour of the cross s…
The branching ratios of K^- absorption at rest in nuclear matter are theoretically investigated in order to understand the mechanism of K^- absorption into nuclei. For this purpose mesonic and nonmesonic absorption potentials are evaluated as functions of nuclear density, the kaon momentum and energy from one- and two-body K^- self-energy, respectively. By using a chiral unitary approach for the s-wave Kbar N amplitude we find that both the mesonic and nonmesonic absorption potentials are dominated by the Lambda(1405) contributions. The fraction of the mesonic and nonmesonic absorptions are ev…
Recent studies of kaonic atoms, few-body kaonic quasibound states and kaonic nuclei are reviewed, with emphasis on implementing the subthreshold energy dependence of the Kbar-N interaction in chiral interaction models that are consistent with the SIDDHARTA K- hydrogen data. Remarks are made on the possible role of the p-wave Sigma(1385) resonance with respect to that of the s-wave Lambda(1405) resonance in searches for strangeness S=-1 dibaryons.
Nuclear system with antikaons, so-called kaonic nuclei, has been a longstanding issue in strange nuclear physics and hadron physics, because they might have exotic nature; In particular, they could be a doorway to the dense matter due to the strong attraction between antikaon and nucleon. Among kaonic nuclei, the three-body system composed of two protons and a single $K^-$ meson, $K^-pp$, is the most essential. In this article, we will report on the recent situation of $K^-pp$ studies in both theoretical and experimental sides. Afterwards, we will explain our latest study of the $K^-pp$ with a…
We propose a method to determine the isoscalar \bar K N scattering length on the lattice. Our method represents the generalization of Lüscher's approach in the presence of inelastic channels (complex scattering length). In addition, the proposed approach allows one to find the position of the S-matrix pole corresponding the the Lambda(1405) resonance.
We propose and examine a new high-density composite of $Λ^* \equiv K^-p = (s \bar{u}) \otimes (uud)$, which may be called {\it Kaonic Proton Matter (KPM)}, or simply, {\it $Λ^* $-Matter}, where substantial shrinkage of baryonic bound systems originating from the strong attraction of the $(\bar{K}N)^{I=0}$ interaction takes place, providing a ground-state neutral baryonic system with a huge energy gap. The mass of an ensemble of $(K^-p)_m$, where $m$, the number of the $K^-p$ pair, is larger than $m \approx 10$, is predicted to drop down below its corresponding neutron ensemble, $(n)_m$, since …
We study kaonic deuterium, the bound K^-d state A_(K d). Within a quantum field theoretic and relativistic covariant approach we derive the energy level displacement of the ground state of kaonic deuterium in terms of the amplitude of K^-d scattering for arbitrary relative momenta. Near threshold our formula reduces to the well-known DGBT formula. The S-wave amplitude of K^-d scattering near threshold is defined by the resonances Lambda(1405), Sigma(1750) and a smooth elastic background, and the inelastic channels K^- d -> NY and K^- d -> NY pion, with Y = Sigma^(+/-), Sigma^0 and Lambda^0, wh…
The Lambda(1405) baryon resonance plays an outstanding role in various aspects in hadron and nuclear physics. It has been considered that the Lambda(1405) resonance is generated by the attractive interaction of the antikaon and the nucleon, as a quasi-bound state below the threshold decaying into the pi Sigma channel. Thus, the structure of Lambda(1405) is closely related to the Kbar N interaction which is the fundamental ingredient to study few-body systems with antikaon. In this paper, after reviewing the basic properties of the Lambda(1405) resonance, we introduce the dynamical coupled-chan…
We study the possibility to bind eight quarks in a molecular hadronic system composed of two nucleons and an antikaon, with the quantum numbers of a hexaquark flavour, in particular with strangeness -1, isospin 1/2, parity -, baryonic number 2 and two possible spins, 0 or 1. These exotic hadrons are motivated by the deuteron, a proton-neutron boundstate, and by the model of the Lambda(1405) as an antikaon proton boundstate. We discuss the possible production of this hadron in the experiments which are presently investigating hot topics like the Theta+ pentaquark or the K- deeply bound in nucle…
A molecule model is proposed for the description of the properties of the kaonic nuclear cluster (KNC) anti-KNN with the structure N(ant-KN)_(I = 0) and quantum numbers I(J^P) = 1/2(0^-), the large binding energy B^(\exp)_(anti-KNN) = 103(6) MeV and the width Gamma^(\exp)_(anti-KNN) = 118(13) MeV, observed recently by the DISTO Collaboration. The theoretical values of the binding energy B^(th)_(anti-KNN) = 118 MeV, the width Gamma^(th)_(anti-KNN) = 142 MeV of the KNC anti-KNN and the density n_(anti-KNN) = 2.71 n_0, where n_0= 0.17 fm^(-3) is the normal nuclear density, reproduce well the larg…
Possible existence of deeply bound kaonic nuclear systems was proposed Akaishi and Yamazaki (2002} more than a decade ago, based on an ansatz that the Lambda* = Lambda(1405) mass is 1405 MeV/c2, where the Lambda* is a Kbar-N quasi-bound state decaying to Sigma-pi. Recently, a large number of data on photo-production of Lambda(1405) in the gamma p to K+ pi{0+-} Sigma{0-+} reaction were provided by the CLAS collaboration Moriya et al.(2013}, and double-pole structure of the Lambda* has been intensively discussed by chiral dynamics analyses {Roca (2013),Mai 2015}, whereas we show that a Lambda* m…
We present three-body nonrelativistic calculations within the framework of a potential model for the kaonic cluster ${K^-}pp$ using two completely different methods: the method of hyperspherical harmonics in the momentum representation and the method of Faddeev equations in configuration space. To perform a numerical benchmark, different $NN$ and antikaon-nucleon interactions are applied. The results of the calculations for the ground state energy for the ${K^-}pp$ system obtained by both methods are in reasonable agreement. Although the ground state energy is not sensitive to the $NN$ interac…
We analyze 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, and find them to be 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. Thus at present there is no experimental evidence of deeply bound K- states in nuclei. However some new phy…
We develop the single-channel local potential for the KbarN system, which is applicable to quantitative studies of Kbar bound states in nuclei. Because the high precision measurement of the kaonic hydrogen by SIDDHARTA reduces the uncertainty of the KbarN amplitude below the KbarN threshold, the local potential should be calibrated in a wide energy region. We establish a new method to construct the local potential focusing on the behavior of the scattering amplitude in the complex energy plane. Applying this method, we construct the KbarN potential based on the chiral coupled-channel approach …
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 a recent study of the Lambda(1405), the suppression of the strange-quark contribution to the magnetic form factor was interpreted as the discovery of a dominant antikaon-nucleon composition for this low-lying state. We confirm this result by calculating the light u- and d-quark contributions to the Lambda(1405) magnetic form factor in lattice QCD in order to determine the extent to which their contributions support this exotic molecular description. Drawing on the recent graded-symmetry approach for the flavor-singlet components of the Lambda(1405), the separation of connected and disconnec…
A phenomenological model is proposed for the analysis of the properties of the Kaonic Nuclear Cluster (KNC) Kpp in its ground state. Inside the KNC K^-pp we describe the relative motion of the protons in the pp pair and the motion of the K^- meson relative to the pp pair in terms of wave functions of 3-dimensional harmonic oscillators. The interaction strength is parameterised in our model by the frequency of the longitudinal oscillation of the K^- meson relative to the pp pair. This parameter was determined with the binding energy and width of the strange baryon Lambda(1405) by assuming that …
The possibility of kaon condensation in high-density symmetric nuclear matter is investigated including both s- and p-wave kaon-baryon interactions within the relativistic mean-field (RMF) theory. Above a certain density, we have a collective ${\bar K}_s$ state carrying the same quantum numbers as the antikaon. The appearance of the ${\bar K}_s$ state is caused by the time component of the axial-vector interaction between kaons and baryons. It is shown that the system becomes unstable with respect to condensation of $K$-${\bar K}_s$ pairs. We consider how the effective baryon masses affect the…
We calculate the shape of the $πΣ$ and $\bar K N$ invariant mass distributions in the $Λ_b \to J/ψ\, πΣ$ and $Λ_b \to J/ψ\,\bar K N$ decays that are dominated by the $Λ(1405)$ resonance. The weak interaction part is the same for both processes and the hadronization into the different meson-baryon channels in the final state is related by SU(3) symmetry. The most important feature is the implementation of the meson-baryon final-state interaction using two chiral unitary models from different theoretical groups. Both approaches give a good description of antikaon-nucleon scattering data, the com…
Anisotropic flow of K's, anti-K's, and lambdas is studied in heavy ion collisions at SPS and RHIC energies within the microscopic quark-gluon string model. At SPS energy the directed flow of kaons differs considerably at midrapidity from that of antikaons, while at RHIC energy kaon and antikaon flows coincide. The change is attributed to formation of dense meson-dominated matter at RHIC, where the differences in interaction cross-sections of hadrons become unimportant. The directed flows of strange particles, $v_1^{K,\bar{K}, Λ}(y)$, have universal negative slope at $|y| \leq 2$ at RHIC. The e…
Non-relativistic Faddeev and Faddeev-Yakubovsky calculations were made for K^-pp, K^- ppn, K^-K^-p and K^- K^-pp kaonic nuclear clusters, where the quasi bound states were treated as bound states by employing real separable potential models for the K^ - - K^ - and the K^ - -nucleon interactions as well as for the nucleon-nucleon interaction. The binding energies and spatial shrinkages of these states, obtained for various values of the Kbar N interaction, were found to increase rapidly with the Kbar N interaction strength. Their behaviors are shown in a reference diagram, where possible change…
