The International Conference on Hypernuclear and Strange Particle Physics (HYP) takes place every two years, bringing together physicists that do research on hadron processes and nuclear systems containing strangeness, from single to multi-strangeness systems, and from few-body systems to neutron stars. The last HYP edition was held in Portsmouth VA (U.S.A.) already four years ago due the...
Heavy-ion collisions at collision energies of a few GeV, explored by e.g. HADES or the STAR fixed-target program, study the properties of matter under extreme conditions like expected in merging neutron stars. At these energies, the lightest hadrons containing strangeness are produced close to their free nucleon nucleon threshold energy. Furthermore, due to the substantial stopping of the...
The STAR experiment provides a perfect machinery for studying strange matter for more than two decades. Recently, we applied the express analysis, which allows online monitoring of the collected physics results. High quality of express calibration and reconstruction provide a unique possibility to run the express production and observe almost in real time strange particles including mesons,...
As the lightest hypernucleus, hypertriton serves as an important benchmark for hypernuclear physics: its ground state spin, iso-spin and uniquely small binding energy (~130 keV) has been used to derive the fundamental property of YN interaction since its discovery. For a long time, it has been generally accepted that the hypertriton has a similar lifetime as free Lambda hyperon
because of the...
The hyperon-nucleon (Y-N) interaction is an essential ingredient in the description of the equation-of-state of high-baryon-density matter. Light hypernuclei (A = 3, 4), being simple Y-N bound states, serve as cornerstones of our understanding of the Y-N interaction. Precise measurements of the lifetimes of light hypernuclei can help provide input to our understanding in the Y-N...
In the last decade, ALICE has been one of the main experiments for the study of the (anti)(hyper) nucleosynthesis at collider.
From the study of the production of antinuclei in all collision systems to the measurement of the antinuclei interaction cross section with matter, ALICE is exploring the full spectrum of measurements involving (anti)(hyper)nuclei thanks to the copious amount of data...
Recent relativistic heavy ion (RHI) collision experiments have extracted conflicting values of the hypertriton (${}_\Lambda^3\mathrm{H}$) lifetime ($\tau({}_\Lambda^3\mathrm{H})$). While the ALICE Collaboration's reported $\tau({}_\Lambda^3\mathrm{H})$ is comparable to the free $\Lambda$ lifetime, the STAR Collaboration's reported value is considerably shorter. A similarly large spread of...
Direct $\Lambda n$ scattering data is extremely important and needed based on the newly confirmed Charge-Symmetry-Breaking (CSB) at a level of ~270 keV from the binding energy difference observed between ground states of $^4_{\Lambda}$He and $^4_{\Lambda}$H. Especially, the $\Lambda n$ data does not exist at all, thus the properties of $\Lambda n$ interaction has been assumed to be identical...
The detection of double hypernucleus having two units of Strangeness has now reached 46 sample events. The only experiment that has continued to detect double-hypernuclei for the last 35 years is experiments using nuclear emulsion as a detector in Japan. During that period, significant progress has been made in experimental and analytical techniques. Under such technological developments, it...
One of the important research goal is to understand $\Xi N$ interaction. For this purpose, at J-PARC, they are planning to produce several bound $\Xi$ hypernuclei. In addition, it is requested to guide what kind of $\Xi$ hypernuclei would be produce as bound state. Considering this situation, I report $\Xi$ hypernuclei with $A=4$ to 10 , that is, $NNN\Xi$, $\alpha \Xi N$, $\alpha\Xi NN$, and...
Recent experimental results for the cascade hypernucleus $^{15}_{\hskip0.27em\Xi}$C ($^{14}$N$+\Xi^-$) are analyzed together with data for $^{12}_{\hskip0.27em\Xi}$Be and $^{13}_{\hskip0.27em\Xi}$B within a Skyrme-Hartree-Fock theoretical approach. Optimal Skyrme parameters are determined for a consistent description of the KISO, IBUKI, KINKA, BNL-E885, BNL-E906, KEK-E224, and KEK-E176 data...
Five $\Xi^- p\to \Lambda\Lambda$ two-body capture events in $^{12}$C and $^{14}$N emulsion nuclei, in which a pair of single-$\Lambda$ hypernuclei is formed and identified by their weak decay, have been observed in $(K^-,K^+)$ emulsion exposures at KEK and J-PARC. Applying a $\Xi^-$-nucleus optical potential methodology to study atomic and nuclear transitions, we confirm that these capture...
X-ray spectroscopy of hadronic atoms give us various information on the strong interaction between hadrons and nuclei. At J-PARC, we are aiming for the world-first detection of the X rays from atoms with a doubly strange hyperon, $\Xi^-$. Recently, two experiments, J-PARC E07 and J-PARC E03, have been performed for the detection of X rays from $\Xi$ atoms. Overview and status of these...
We study the energy spectra of $\Xi$ hypernuclei $^{15}_\Xi$C and $^{12}_{\Xi}$Be with a relativistic mean field (RMF) model. The RMF parameters are optimized to reproduce the average energy of KINKA and IRRAWADDY events for the ground state and also the average energy of KISO and IBUKI events for the excited state in $^{15}_\Xi$C. The depth of the $\Xi-N$ mean field potential is found to be...
The inclusion of new ingredients that are expected to be specially relevant at higher energies could reveal more information about the physics behind the NLO terms of the chiral Lagrangian. In the present work, we explore the relevance of including partial waves higher than the $L=0$, which is usually the only component considered in the literature to study the ${\bar K}N$ scattering...
The measurements of $\pi\Sigma$ mass distributions in the $\gamma p \longrightarrow K^{+} \pi\Sigma$ photoproduction reaction [1, 2] probe the energy region of the $\Lambda(1405)$ resonance, just below the $\bar{K}N$ threshold, and present new challenges for the theoretical models of $\bar{K}N-\pi\Sigma$ coupled channels interactions. Adopting the model presented in [3] we describe the...
The attractive nature of $\bar{K}N$ interaction has stimulated theoretical and experimental searches for $K^-$ bound states in different systems. In particular, many theoretical calculations devoted to the lightest possible system $\bar{K}NN$ have been performed using different methods: Faddeev equations with coupled channels, variational methods, and some others, see a review \cite{review}...
In recent years, the possible existence of deeply-bound $\bar K$ nuclear bound states has been widely discussed as a consequence of the strongly attractive $\bar KN$ interaction in I = 0 channels. Very recently, J-PARC E15 experiment reported an observation of the simplest kaonic nuclei, $\bar KNN$, in the $\Lambda p$ invariant-spectrum of the in-flight $K^-$ reaction on helium-3...
We investigated the meson-baryon scattering using time-order perturbation theory (TOPT) based on a manifestly Lorentz-invariant formulation of baryon chiral perturbation theory. Effective potentials are defined as sums of two-particle irreducible contributions of time-ordered diagrams and the renormalized scattering amplitudes are obtained by solving the integral equation, which is derived...
The last two decades witnessed the discovery of a large number of hadron resonances beyond expectation. They are candidates of exotic hadrons. This talk will review the theoretical understanding of exotic hadrons with strangeness and charm, focusing on hadronic molecules.
Belle and Belle II are B-factory experiments using electron-positron collisions. Not only particle physics, but also hadron spectroscopy is actively pursued in the experiments. In this talk, we will present recent results on exotic (and conventional) hadrons from the Belle experiment and on the status and prospects of the Belle II experiment.
Understanding the dynamics of hadrons with strangeness has received a lot attention over the past decades in connection with the study of exotic atoms, the analysis of strangeness production in particle and nuclear research facilities, and the investigation of different strange phases in the interior of neutron stars. One venue of interest in the field of strangeness is the study of strange...
The hyperon puzzle is one of the primary problems in neutron star physics. $\Lambda$ baryons are expected to appear in neutron star matter at $(2-4)\rho_0$ when two-body interactions based on hypernuclear data are used, but hyperons soften the equation of state (EOS) and make it difficult to explain the existence of $2M_\odot$ neutron stars. Thus $\Lambda$ should feel a strong repulsive...
In non-central heavy-ion collisions (HIC), the large initial angular momentum can induce a non-vanishing polarization for hadrons with non-zero spin. The global spin alignment of vector mesons, quantified by the $00^{th}$ element of spin density matrix $(\rho_{00})$, can offer information on the spin-orbital interactions of the QCD medium. Surprisingly large signal of vector meson ρ00 compared...
The matter created in non-central heavy-ion collisions is expected to have an initial orbital angular momentum carried by two colliding nuclei. Such an angular momentum would be transferred to the global polarization due to the spin-orbit coupling. The STAR Collaboration observed global polarization of \Lambda hyperons in Au+Au collisions in a wide range of collision energy $\sqrt{s_{NN}}$ =...
We’ll discuss our recent progress on studying light hypernuclei by using heavy ion beams, nuclear emulsions and machine learning techniques. In recent years, hypernuclear studies can also be performed by using energetic heavy ion beams, and some of these experiments have revealed unexpected results on three-body hypernuclear states, i.e., shorter lifetime [1-7] and larger binding energy [8] of...
Scattering experiments involving a hyperon and a proton are the most effective methods for investigating two-body hyperon–nucleon ($YN$) interactions, as is the case in various intensive studies on $pp$ and $np$ scattering, which are aimed at understanding nucleon–nucleon ($NN$) interactions. Scattering observables, such as differential cross sections and spin observables, are essential...
A large amount of data collected over the past several decades allowed a detailed understanding of the nucleon-nucleon (NN) interaction. On the other hand, experimental difficulties prevent us from obtaining a comprehensive understanding of interactions involving other members of the baryon octet -- namely the hyperons (Y). Such difficulties are associated with the short lifetime of hyperons,...
We review the main mechanisms leading to the production of light and intermediate mass nuclei and hypernuclei in relativistic nuclei collisions. We demonstrate that in these many-body phenomena one can separate and describe the processes characterising excited nuclear matter properties which have a primary importance for nuclear/particle physics and astrophysics. Such deep-inelastic...
In this talk, I will present the latest status of first-principles lattice QCD calculations of hadron interactions, in particular for those with strangeness. I introduce our theoretical framework, the HAL QCD method, and discuss its advantage over the traditional method.
I will then show our numerical results obtained near the physical point, as well as the recent experimental confirmation...
The instability of hyperons against the weak interaction hinders the experimental extraction of baryon-baryon low-energy observables in the strange sector. In this energy regime, a reliable numerical procedure to obtain information of nuclear physics quantities is lattice QCD, a high-demanding numerical approach to solve the complex dynamics of strongly-interacting systems directly from the...
Bridging the gap between nuclear physics and its fundamental theory, quantum chromodynamics (QCD), is of great importance. Since QCD is non-perturbative at low energies, lattice simulations, dubbed LQCD, are the only viable way to obtain ab initio QCD predictions for low energy nuclear physics.
These calculations are done, however, in a finite box, and are limited only to systems composed...
We present results on the anisotropic transverse flow of kaons ($K^+$, $K^0_S$ and $K^-$) in Au+Au collisions at $\sqrt{s_\mathrm{NN}} = 2.42\,\mathrm{GeV}$ measured with HADES. It was proposed already in the mid-nineties that kaon flow close to its production threshold might be a good probe for the kaon-nucleon potential and, consequently, for the nuclear equation-of-state (PRL 74 (1995)...
HYDRA (HYpernuclei Decay at R3B Apparatus) is a physics program within the R3B collaboration at the decay spectroscopy of hypernuclei produced from heavy-ion collisions at GSI/FAIR. The program aims at measuring with high resolution the in-flight pionic decay of light and medium mass hypernuclei. The pion tracker is conceived as a time projection chamber(TPC) inside the GLAD magnet of the R3B...
ALICE determines the scattering parameters of D mesons with light-flavor hadrons
Daniel Battistini for the ALICE Collaboration
The strong interaction among D mesons and light-flavor hadrons was completely out of experimental reach until recently. The scattering parameters governing elastic and inelastic D-pion/kaon/proton collisions are completely unknown. This poses strong limitations...
The production of (anti)deuterons in relativistic heavy-ion collisions is still theoretically not well understood. The particle yield can be qualitatively described by two different mechanisms of particle creation. The first of the two, the coalescence model, describes the (anti)deuteron’s creation as a result of final-state interactions among (possibly off-shell) nucleons after the chemical...
We present two methods, the Nucleon-Lambda Tamm Dancoff Approximation (NL TDA) and the Equation of Motion Phonon Method (EMPM) suitable for calculating hypernuclear energy spectra and structure. These methods are applicable for hypernuclei of wide range of masses with one Lambda particle replacing one nucleon in an even-even nuclear cores. Using an effective Lambda-nucleon potential both...
Missing-mass spectroscopy by using the $(e,e^{\prime}K^{+})$ reaction was developed at Jefferson Lab (JLab). The energy resolution of 0.5 to 1 MeV/$c^{2}$ in FWHM is achievable thanks to a high quality beam provided by JLab and high resolution spectrometers dedicated to hypernuclear measurements. In addition, one of important features is an accurate energy calibration by using $\Lambda$ and...
The existence of the bound state of iso-triplet three-body hypernucleus $\Lambda$nn attracts attention since possible events were reported by HypHI collaboration at GSI. Missing-mass spectroscopy with the $(e,e^{\prime}K^{+})$ reaction has been performed at Jefferson Lab (JLab) to investigate the $\Lambda$nn hypernucleus (JLab E12-17-003 Experiment). A tritium gas of 0.1 g enclosed by a target...
Electroproduction of hypernuclei is an object of current interest. Precise and reliable predictions of the cross sections in hypernucleus electroproduction are important both in planning experiments and data analysis. We will discuss some uncertainties in description of the reaction mechanism based on impulse approximation, particularly, we will show effects of proton motion in the target...
Physicists investigate the subatomic world by bombarding their subject of study with a hail of tiny subatomic “bullets”. From the way these “bullets” bounce off their target one can infer a wealth of detailed information about the target’s structure. Different kinds of subatomic “bullets” probe different aspects of the target, certain important aspects of the force holding atomic nuclei...
As a recent topic of heavy flavor systems, exotic charmonia called $X,Y,Z$ have been observed experimentally above the meson-meson threshold. Masses of $X,Y,Z$, however, are not reproduced by the Cornell potential only with the degrees of freedom of $\bar{c}c$. This indicates that the $X,Y,Z$ states have coupled channel effects of $\bar{c}c$ and meson-meson states strongly.
Because of the...
We employ a feed-forward artificial neural network (ANN) to extrapolate, at large model spaces, the hypernuclear No-Core Shell Model results of Refs. Few-Body Syst, 55 (2014) 857 and Few-Body Syst. 62 (2021) 94 for the $\Lambda$ separation energies of the lightest hypernuclei, $^3_\Lambda$H, $^4_\Lambda$H and $^4_\Lambda$He, obtained with chiral nucleon-nucleon and hyperon-nucleon...
We are going to perform missing mass spectroscopy of various $\Lambda$ hypernuclei using the $(e,e'K^{+})$ reaction at the Thomas Jefferson National Accelerator Facility (JLab). This experimental campaign contains the first measurement of medium-mass hyperisotopes of $^{40}_{\Lambda}\mathrm{K}$ and $^{48}_{\Lambda}\mathrm{K}$ using isotopically enriched calcium target [JLab E12-15-008]. The...
At K1.8 beam line in the Hadron Hall of J-PARC, high-precision missing-mass spectroscopy for $\Xi$ hypernuclei ( J-PARC E70 experiment ) is in preparation. In the J-PARC E70 experiment, the high-intensity $1.8 ~{\rm GeV}/c$ $K^{-}$ meson beam will be used for production of $\Xi$ hypernuclei ($^{12}_{\Xi}$Be) via $(K^{-}, K^{+})$ reaction. A newly installed magnetic spectrometer "S-2S" has a...
Measurement of density of emulsion layer is very important for analyzing double strangeness hypernuclei. Because the mass of double hypernucleus is reconstructed by measuring the kinetic energy which is converted from the range of decay daughter nuclei in nuclear emulsion plate using range-energy relation. Alpha tracks from thorium and uranium series, which have monochromatic energy, were used...
The hypertriton ($^3_\Lambda$H) lifetime puzzle stands for the deviation between the physical picture derived from the binding energy in the old emulsion experiment and the measured lifetime in heavy-ion experiments. To pin down the hypertriton lifetime puzzle, it is clear that an independent experimental approach is needed to improve the situation. We plan to populate and measure the...
One of methods to study the properties of hot and dense nuclear matter created in high-energy nuclear collisions is femtoscopic measurements. This method provides information about space-time characteristics of the particle emission region, which has a size and lifetime of the order of $10^{-15}$ m and $10^{-23}$ s, respectively. From non-identical particle correlations, one can obtain...
The Julich-Bonn-Munich Group aims at an extensive study of the baryon-baryon (BB) interaction involving strange baryons ($\Lambda$, $\Sigma$, $\Xi$) within SU(3) chiral effective field theory. An overview of achievements and new developments over the past few years will be provided. Among the issues covered are:
$\bullet$ Derivation of the leading charge-symmetry breaking (CSB) interaction in...
We investigate $S=-1$ and $-2$ hypernuclei with $A=4-7$ employing the Jacobi-NCSM approach [1] and in combination with baryon-baryon (BB) interactions derived within the frame work of chiral effective field theory. The employed BB interactions are softened using the so-called similarity renormalization group (SRG) [2] in order to speed up the convergence. Such a SRG evolution is only...
The two-particle momentum correlation function from high-energy nuclear collisions is beginning to be used to study hadron-hadron interaction. In this talk, we discuss how the hadron-hadron interaction can be determined from the correlation function data. Based on the theoretical and experimental studies in strangeness sectors, we review the importance of the coupled-channel effect and the...
Light hypernuclei containing one or two $\Lambda$ baryons is the subject of an ongoing experimental campaign aiming to study the spectrum of these systems, as well as the 2 and 3-body interaction between $\Lambda$ hyperons and nucleons.
In this presentation we review the theoretical study of these systems within the framework of Baryonic Effective Field Theory (BEFT). Constrained to...
A new experiment is prepared at the Mainz Microtron facility to determine the hypertriton Lambda binding energy via decay pion spectroscopy, which was successfully pioneered with hydrogen-4-$\Lambda$ in the last decade. The experiment makes use of a novel high luminosity lithium target with a length of 50$\,$mm while being only 0.75$\,$mm thick to keep momentum smearing of the decay pions low....
The hyperon puzzle in neutron stars is one of the most challenging questions to be solved in nuclear and astrophysics nowadays. To approach this problem, we need to clarify possible repulsion in the $\Lambda N$ interaction in dense nuclear matter, in other words, possible repulsion in the $\Lambda NN$ three-body force. In order to extract information on the $\Lambda NN$ three-body force,...
On the endeavour to explore the strong interaction among hadrons, the ALICE Collaboration has extended the experimental measurements beyond those of two particles, studying three-body interactions. These measurements provide unique information on many aspects of strongly-coupled systems, like exotic bound states and the genuine three-body interactions. The latter constitute an important...
Remarkable progress has been achieved in recent decades towards quantitative understanding of nuclear forces and currents in the framework of chiral effective field theory. While accurate and precise two-nucleon potentials from chiral EFT are already available, the three nucleon forces are less well understood and constitute an important frontier in nuclear physics. I will review the current...
Two-body hyperon-nucleon interaction models often assume additional 3-body $\Lambda NN$ terms to reproduce the empirically derived value of $D = 30$ MeV for the $\Lambda$-nucleus potential depth. There is no consensus yet on the sign and size of such 3-body terms. Applying consistently a density-dependent $\Lambda$-nucleus optical potential to binding energy calculations of observed $1s$ and...
A survey is given on the issue of strangeness contributions to the composition of dense matter in the core of neutron stars. The first part of this presentation reviews empirical constraints on the neutron star equation-of-state. The second part focuses primarily on our present understanding of hyperon-nuclear three-body forces and their role in providing a possible solution to the so-called...
The study of the strong interaction among hadrons is an essential question in nuclear physics. It has implications both for fundamental theories, such as QCD, as well as for the understanding of the structure of dense stellar objects, such as neutron stars.
Traditionally, the experimental access to the properties of the strong force is primarily realized by scattering and hypernuclei...
Geometry and dynamics of the particle-emitting source in heavy-ion collisions can be inferred via the femtoscopy method. Two-particle correlations at small relative momentum exploit Quantum Statistics (QS) and the Final State Interactions (FSI), which allow one to study the space-time characteristics of the source of the order of $10^{−15}$ m and $10^{−23}$ s. Femtoscopic measurements allow...
HADES is a versatile spectrometer for studying various aspects of low energy QCD operating at the SIS18 synchrotron located at the GSI/FAIR in Darmstadt,
Germany. Primarily designed to study dilepton production in proton and heavy ion induced collisions with its capability to identify also hadrons become an excellent tool to explore strange hadrons production. Λ, Σ, Ξ(1321), Λ(1405), Λ(1520),...
In the journey to explore the strong interaction among hadrons, ALICE has for the first time flared out its femtoscopic studies to nuclei. The large data sample of high-multiplicity pp collisions at $\sqrt{s} = 13$ TeV allows the measurement of the proton-deuteron (p-d), kaon-deuteron ($\mathrm{K^{\pm}}$-d) and the Lambda-deuteron ($\Lambda$-d) momentum correlations. The femtoscopic study of...
Relativistic heavy-ion collisions can study properties of nuclear matter in high-energy experiments like the STAR experiment. One of the methods to learn about bulk matter is the femtoscopy technique, which relies on information carried by the particles produced during the collisions. The emission source parameters, like space-time characteristics, are provided using femtoscopic quantities....
We consider the experimental data on yields of protons, strange $\Lambda$’s, and multistrange baryons ($\Xi$, $\Omega$), and antibaryons production on nuclear targets, and the experimental ratios of multistrange to strange antibaryon production, at the energy region from SPS up to LHC, and compare them to the results of the Quark-Gluon String Model calculations. In the case of heavy nucleus...
We are aiming for measurement of X rays form $\Xi^-$ atom to obtain the information on $\Xi$A interaction.
In 2021, We performed $\Xi^-$-Fe atomic X-ray spectroscopy experiment (J-PARC E03) at J-PARC K1.8 beam line. $\Xi^-$ hyperons were produced via the (K$^-$, K$^+$) reaction. Beam K$^-$ and scatterd K$^+$ were measured by magnetic spectrometers and X rays from $\Xi^-$-Fe atom werw...
Measurements of anisotropic flow can be used to study transport properties and the evolution of the quark-gluon plasma (QGP), the hot and dense medium produced in heavy-ion collisions that expands collectively. In recent years, several similar features have been observed in high-multiplicity collisions of small systems, such as pp or p--Pb. However, it is still under debate whether the origin...
The $\Lambda$ binding energy difference, which is called the charge symmetry breaking in the ground states of a pair of A = 4 hypernuclei, \hl and \hel, was measured to be $\Delta B_{\Lambda}^4(0_{g.s.}^{+})\approx 350~$keV in nuclear emulsion experiments in 1970s. In the 2015 experiment from J-PARC, the binding energy difference in excited states $\Delta B_{\Lambda}^4(1_{exc}^{+})\approx...
The field of strangeness physics is still post seven decades from its birth holds the exclusive characteristic of having more conjectures than answers in both theoretical and experimental dimensions. One of the major among the open question is the knowledge about background effect on various hyperon-baryon channels playing crucial role from heavy-ion collisions to celestial objects to name a...
NA61/SHINE is a multi-purpose fixed-target experiment located at the H2 beamline of the CERN North Area. One of the main goals of the experiment is to study the phase transition and search for the critical point of the strongly interacting matter. Strangeness production is a long-known valuable probe for understanding particle production in high-energy physics due to the absence of strange...
The E12-17-003 Experiment was carried out successfully at Jefferson lab in 2018 using a pressurized tritium target. By utilizing the Hall A high-resolution spectrometers and the $^{3}H(e,e’K^{+})Λnn$ reaction, enhancements which may correspond to the possible $Λnn$ resonance and a pair of $ΣNN$ sate were observed with an energy resolution of 1.21 MeV (σ), although the greater statistics are...
The study of the strong interaction among stable and unstable hadrons is a fundamental question in nuclear physics and it is a key ingredient for the determination of the Equation of State of dense stellar objects, such as neutron stars. Two-particle correlation measurements are a prominent tool to probe the strong interaction with high precision even in the multi-strangeness sector, where...
A recent JLab experiment exploiting the $^3$H(e,e'K$^+$)$^3_\Lambda$n reaction to investigate the existence of a threshold $^3_\Lambda$n resonance that would place constraints on the $\Lambda$n scattering length, observed a structure in the spectrum that was interpreted to be a $\Sigma$NN resonance [1,2]. Such a $\Sigma$NN resonance could have isospin T=0 or T=1. Garcilazo argued in 1987 on...
The overall scanning method of the entire volume of the nuclear emulsion irradiated in the E07 experiment at J-PARC can provide to discover events that were not observed by the already-completed analyses with the emulsion-counter-hybrid method. Therefore, further analysis with the overall scanning technique can be used to observe a large number of single-$\Lambda$ hypernuclei, however, it...
We report on our recent result [1] concerning in-medium $\Lambda$ isospin impurity derived from charge symmetry breking (CSB) in the mirror hypernuclei ${\rm ^4_\Lambda H}-{\rm ^4_\Lambda He}$. Using pionless effective field theory and partially conserved baryon-baryon SU(3) flavor symmetry we find that the in-medium admixture amplitude ${\cal A}_{I=1}$ in the dominantly isospin $I=0$...
Very recently, from January till March in 2022, the WASA-FRS HypHI experiment was performed at GSI for measuring the lifetime of the hypertriton and the ${}^{4}_{\Lambda}\mathrm{H}$ hypernucleus precisely as well as for confirming whether or not the $nn\Lambda$ bound state can exist. The experiment has been carried out with the WASA central detector with a complex of additional dedicated...
The distribution of neutrons with respect to protons in heavy nuclei is strongly related to isospin dependence of the nuclear equation of state. There exist several experimental methods to determine the neutron skin thickness in these nuclei: scattering of hadronic probes like $\pi$, p, and $\alpha$ particles on nuclei, antiproton-nucleus scattering or absorption, the electromagnetic dipole...
The measurement of the production and the lifetime of the hypertriton with the ALICE detector at the LHC is presented to address some of the key open questions of hypernuclear and particle physics.
The hypertriton is a bound state of a proton (p), a neutron (n) and a Λ and it is characterized by a very low binding energy and a large wave function. It is still unclear how such a fragile...
The production of hyperons serves as a tool to investigate the strong interaction in the non-perturbative energy regime. While there are several experimental results for $\Lambda$ hyperons in p+p reactions, measurements of the $\Sigma^{0}$ production are scarce. This talk presents a study of the $\Sigma^{0}$ production mechanism via the exclusive reaction $pp \to pK^{+}\Sigma^{0}$ at a beam...
To understand the mechanism of the sizable charge symmetry breaking between $^4_\Lambda$H and $^4_\Lambda$He, we plan to measure the gamma-transition energy of $^4_\Lambda$H ($1^+→0^+$) with a high-resolution Germanium detector array (Hyperball-J) at J-PARC (E63 experiment). The $^4_\Lambda$H is efficiently produced as hyperfragments from the in-flight $^7$Li $(K^-,\pi^-)$ reaction....
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 $\Lambda(1405)$ resonance, below the $\bar{K}N$ threshold. Based on this picture, it may be expected that the $\bar{K}N$ interaction also...
The existence of a quasi-bound state of antikaon and nucleus, kaonic nucleus, has been discussed ever since the $\bar{K}N$ interaction in $I=0$ channel was confirmed to be strong attractive.
The $\bar{K}NN$ quasi-bound state is the lightest kaonic nucleus which is considered to be $I=1/2$ and $J^\pi = 0^-$.
To search for the $I_{z}=+1/2~\bar{K}NN$ state we conducted the J-PARC E15 experiment...
The $\overline{\rm K}$p system is characterised by the presence of several coupled channels, systems like $\rm \overline{K}^0$n and $\rm \pi\Sigma$ with a similar mass and the same quantum numbers as the $\rm{K}^{-}$p state. The strengths of these couplings to the $\rm{K}^{-}$p system are of crucial importance for the understanding of the nature of the $\Lambda(1405)$ and of the attractive...
So far, the $(e,e' K^+)$ reaction spectroscopy is the only way to achieve sub-MeV energy resolution in Lambda hypernuclear reaction spectroscopy. As a part of the J-PARC hadron hall extension project, a new momentum dispersion matching beamline HIHR will be constructed. It will open the door to other reaction spectroscopy for precise measurement of Lambda hypernuclei with pion beams.
I will...
$s$-shell to $sd$-shell hypernuclear gamma-ray spectroscopies were carried out at KEK-PS, BNL-AGS and J-PARC using germanium detector arrays as the series of Hyperball project. These precise measurements of hypernuclear level structures gave various information on the $\Lambda$N interaction. In particular, the result from the gamma-ray spectroscopy of $^4_\Lambda$He ($1^+ \to 0^+$) M1...
The $(e, e'K^+)$ reaction experiments with several nuclear targets performed recently at the Jefferson Lab have provided high-resolution spectroscopic data. They are very fruitful in disclosing hypernuclear structure details and also in understanding hyperon-nucleon fundamental interaction properties.
Among others, the $^{10}$B $(e, e'K^+)$ $_{\,\Lambda}^{10}$Be reaction data are quite...
Although not perfectly conserved, SU(3) group structures are useful guidelines for interactions of octet baryons by the exchange of scalar, pseudo-scalar, and vector nonet mesons by providing constraints on meson-baryon vertices in terms of a few fundamental SU(3) coupling constants - as incorporated in baryon interaction models. As discussed in [1,2], the SU(3) relations are especially useful...
Intense $K^-$ beam at J-PARC will enable us to investigate strangeness $-2$ systems, namely $\Xi$-hypernuclei and double-$\Lambda$ hypernuclei. In particular, the high-resolution S-2S spectromter will be a key ingredient for a systematic study of these systems by means of $(K^-,K^+)$ reactions.
The J-PARC E75 experiment plans to produce $^5_{\Lambda\Lambda}{\mathrm{H}}$ as a decay product...
The microscopic composition and properties of matter at super-saturation densities have been a subject of intense investigation for decades. The scarcity of experimental and observational data has led to the necessary reliance on theoretical models. However, there remains great uncertainty in these models, which, of necessity, have to go beyond the over-simplified assumptions that high-density...
Hyperon-proton scattering experiment is one of the most direct methods to study the $YN$ interaction, as in the case of the $NN$ interaction. Although it was experimentally difficult due to short lifetime of hyperons for a long time, we successfully performed novel high-statistics $\Sigma p$ scattering experiment at J-PARC (J-PARC E40 experiment). One of the physics motivations was...
We review the composition and the properties of neutron stars and proto-neutron stars with a nucleonic and hypernucleonic core within a relativistic mean-field approach. We make use of the FSU2H model, which has been updated according to the recent analysis on the Xi baryon potential, and extend it to include finite temperature corrections. The calculations are done at both constant...
Recently, we have proposed a new experiment (J-PARC P90 experiment) to measure the missing-mass spectrum around the $\Sigma N$ threshold in the $d(K^-, \pi^-)$ reaction at 1.4 GeV/$c$. A clear enhancement was observed near the $\Sigma N$ threshold, so called "$\Sigma N$ cusp", for a long time ago. However, the dynamical origin of this enhancement remains unclear as yet. Especially, whether...
We propose an experiment for measuring the beta decay of $\Lambda$ hypernuclei to study possible modification of baryon structure in nuclear matter due to the interaction between the quarks in the baryon and the meson field in nuclear matter. The QMC (Quark Meson Coupling) model predicts that the axial charge $g_A$ of a $\Lambda$ decreases by 10% at maximum in nuclear matter, and the beta...
The $\Xi$particle-nucleon interaction is the last piece of the nuclear force study that has been extended to the strange quark, and the $\Xi$ hypernuclear spectroscopy experiment will provide us the rich information. We are planning a series of $\Xi$ hypernuclear spectroscopy experiments using $(K^-, K^+)$ reactions at the Japan Proton Accelerator Re-search Complex (J-PARC), K1.8...
There is presently no consensus on how the $\phi$ meson mass and width will change once it is put in a dense environment such as nuclear matter. While many theoretical works exist, connecting them with experimental measurements remains non-trivial task, as the $\phi$ meson in nuclear matter is usually produced in high-energy pA reactions, which are generally non-equilibrium processes.
In...
We have used an isobar model to study the $K^+\Sigma^-$ photoproduction reaction on a neutron target with focus on the resonance region. In order to achieve a reasonable agreement with the data, we included spin-3/2 and spin-5/2 nucleon resonances in the consistent formalism [1,2], where spurious lower-spin modes vanish in the amplitude, together with a $\Delta$ resonance and two kaon...
$\Xi^-$ atomic X-ray spectroscopy is a useful method for understanding the strong interaction in the S=-2 sector. One of the experimental difficulties is that the in-flight decay of $\Xi^-$ hyperon makes a huge background. We introduced a selection of $\Xi^-$-stop events using a nuclear emulsion, expecting a clean X-ray spectrum with a good significance. We performed the first Ξ- atomic...
The recent observation of two-solar-mass neutron stars rules out most of the current models of hyperonic matter equation of state, which favour the appearance of hyperons in the neutron star interior but predict maximum masses (Mmax) incompatible with data. This issue, referred to as “hyperon puzzle”, strongly suggests that the present understanding of nuclear interactions involving hyperons...
Light quarks form diquark clusters in hadrons and hadronic matter. We construct a chiral effective theory of spin 0 (scalar-pseudo-scalar) and 1 (axial-vector and vector) diquarks. The masses of the diquarks contain chiral invariant and non-invariant terms. The latter is given in terms of chiral condensate and thus variant in finite temperature and/or density. The parameters of the effective...
The $K^+ \; \Sigma^-$ photoproduction off the neutron is investigated with an Isobar model. Measurements of differential cross sections and photon beam asymmetries from the LEPS and CLAS collaborations were used to fit the parameters of the model, which are mainly the coupling constants of numerous resonances. However, fitting a model with a large number of free parameters can be problematic...
Because the $\Lambda(1405)$ cannot be explained by the $qqq$ picture in the constituent quark model, it is expected to have an internal structure of, for instance, the $\bar{K}N$ molecular state. In recent experiments, many candidates for exotic hadrons have been discovered in the heavy quark sector such as $XYZ$ mesons, for which hadronic molecular states and tetraquark states are proposed....
We have been performed a high resolution hypernuclear mass spectroscopy measurement by the $(e,e’K^{+})$ reaction at the Thomas Jefferson National Accelerator Facility (JLab). The differential cross section for the $\Lambda/\Sigma^0$ electroproduction is fundamental information to estimate yields of hypernuclei in experiments. Although $\Lambda/\Sigma^0$ photoproduction has been studied well...
In the nucleon-nucleon ($NN$) interaction, realistic nuclear force models have been established with $NN$ scattering data. On the other hand, there are relatively large uncertainties due to limited $\Lambda N$ scattering data in case of the $\Lambda N$ interaction. The spectroscopic studies of $\Lambda$ hypernuclei have played an important role in knowledge of the effective $\Lambda n$...
The SU(3) flavor symmetry in the quark model for baryons allows as many $\Xi$ resonances as $N^{*}$ and $\Delta^{*}$ combined. Only a handful of these states have been identified experimentally and among these states, only six states have three and four-star status according to PDG. The GlueX experiment, in Jefferson Lab's Hall D using a photon beam of energies up to 12 GeV allows us to study...
A large-acceptance superconducting spectrometer for a series of hadron experiments, Hyperon Spectrometer, has been developed at J-PARC. The first experiment, E42, was performed using the Hyperon Spectrometer in 2021 to search for an exotic 6-quark state, the H-dibaryon. The E42 detector is sensitive to search for the H-dibaryon over a broad mass range, measuring ${\Lambda}p\pi^−,...
While various theoretical studies have been performed for the excited $\Xi(1620)$ and $\Xi(1690)$ states, their nature was not well understood due to the lack of experimental data. Recently, the invariant mass distribution of the $\Xi_c\rightarrow\pi\pi\Xi$ decay was observed by the Belle collaboration [1].
By fitting the invariant mass distribution with the Breit-Wigner distribution, the...
We performed the J-PARC E40 experiment to measure the $\Sigma p$ scattering from 2018 to 2020. Together with the $\pi^{-}p\to K^{+}\Sigma^{-}$ data, the $\pi^-p\to K^0\Lambda$ events were accumulated as by-product data. The analysis confirmed that $\Lambda$ could be identified with reasonable accuracy of S/N ratio $\sim2.67$. Plus, we found the polarization of $\Lambda$ ($P_{\Lambda}$) was...
Recently, a few $\Xi$-hypernuclear events have been reported from emulsion experiments. The $\Xi$-nucleus interaction was found to be attractive. However, the binding energies and their widths of $\Xi$ hypernuclei are still uncertain based on the emulsion events, so energy spectra measured with higher statistics by spectroscopic experiments are needed.
We are going to perform a...
The recent discoveries of the pentaquark, $P_C$, states and $XYZ$ mesons in the charmed quark sector has initiated a new epoch in hadron physics. The existence of exotic multi-quark states beyond the conventional three and two quark systems has obviously been realised. Such states could manifest as single colour bound objects, or evolve from meson-baryon and meson-meson interactions,...
The ΛΛ pairing effects in spherical and deformed multi-L hyperisotopes are investigated in the framework of the Skyrme-Hartree-Fock approach employing a d pairing force with the pairing strength of L hyperons being 4/9 of that for nucleons. For spherical hyperisotopes, the occurrences of magic numbers -S = 2, 8, 18, 20, 34, 58, 68, and 70, which are attributed to a Woods-Saxon-like Λ hyperon...
The hadron physics sector with strangeness content faces a promising era with the arrival of new experimental data on the strong interaction between antikaons and nucleons (nucleii). The most recent and the upcoming measurements performed with traditional and new experimental approaches will be reviewed.
Measurements of correlations between particle pairs with low relative momentum via...
Kaonic atoms are atomic systems where an electron is replaced by a negatively charged kaon, containing a strange quark, which interacts with the nucleus also by the strong interaction. As a result, the study of kaonic atoms offers the unique opportunity to perform experiments equivalent to scattering experiments, but at vanishing relative energy. These experiments will allow to study the...
The strong interaction theory in the low energy regime, is still missing fundamental experimental results in order to achieve a breakthrough in its understanding. Among these, the investigation of the low-energy kaon-nucleon/nuclei processes plays a key-role. The talk will give an outline of the results obtained by the AMADEUS experiment performed at the DAFNE Collider of LNF-INFN.
The...
The low-energy $K^-N$ interaction is currently described by chiral coupled-channel meson baryon interaction models. Above threshold, all the models agree between each other since their parameters are fitted to available low-energy $K^-N$ observables. However, in the subthreshold region, relevant for $K^-$ bound states, various models have different energy-dependence, which leads to a large...
Among the light baryons, the $J^\pi = \frac{1}{2}^-$ $\Lambda(1405)$ baryon is an important special case by sitting just below the $\bar{K}N$ threshold and decaying almost exclusively to $\Sigma\pi$. It has long been hypothesized to be either a molecular bound state or a continuum resonance, or that it is a simple quark-model resonance, the $P$-wave companion of the $\Lambda(1520)$. In...
The GlueX experiment located at Jefferson Lab studies the spectrum of hadrons using photoproduction on a $LH_2$ target in a wide variety of final states. With its detector system capable of measuring neutral and charged final state particles over almost the full solid angle, and very good particle identification capabilities, GlueX can measure many different hadrons containing strangeness. A...
A new magnetic spectrometer S-2S is being installed at the K1.8 beam line of J-PARC, Japan. The installation is planned to be completed this year. The first experimental attempt is to measure the binding energy of a $\Xi$ hypernucleus $^{12}_{\Xi}$Be by a missing-mass method through the $(K^{-},K^{+})$ reaction. An expected binding-energy resolution is about $2~$MeV (FWHM) which is the best...
Study of nuclear matter attracts wide interests in the field of hadron physics research. A project to study high-density nuclear matter using heavy ion collisions in a beam energy range of few GeV is being prepared at J-PARC. According to past experiments and model calculations, such heavy ion collisions can produce a high-baryon density matter, which has few times larger density than a normal...
The J-PARC Hadron Experimental Facility was constructed with an aim to explore the origin and evolution of matter in the universe through the experiments with intense particle beams. In the past decade, many results on particle and nuclear physics have been obtained at the present facility. To expand the physics programs to unexplored regions never achieved, the extension project of the Hadron...
The present status and perspectives of hypernuclear physics (strangeness nuclear physics) are summarized based on the presentations reported in the HYP2022 conference. The talk will cover experimental activities at J-PARC, JLab, LHC, DA$\Phi$NE, GSI/FAIR, MAMI etc., and highlights of recent results and near future plans are reviewed. By combining with theoretical progress, a personal view of...
