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Toshimitsu Yamazaki

Publications and source records attributed to Toshimitsu Yamazaki.

At least 19 recordsLinked to original sources

High-density kaonic-proton matter (KPM) composed of Lambda* equiv K-p multiplets and its astrophysical connections

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 the attractive interaction is further increased by the Heitler-London type molecular covalency, as well as by chiral symmetry restoration of the QCD vacuum. Since the seed clusters ($K^-p$, $K^-pp$ and $K^-K^-pp$) are short-lived, the formation of such a stabilized relic ensemble, $(K^-p)_m$, may be conceived during the Big-Bang Quark Gluon Plasma (QGP) period in the early universe before the hadronization and $quark$-$anti$-$quark$ annihilation proceed. At the final stage of baryogenesis a substantial amount of primordial ($\bar{u},\bar{d}$)'s are transferred and captured into {\it KPM}, where the anti-quarks find places to survive forever. The expected {\it KPM} state may be {\it cold, dense and neutral $\bar{q} q$-hybrid ({\it Quark Gluon Bound (QGB)}) states, $[s(\bar{u} \otimes u) ud]_m$,} to which the relic of the disappearing anti-quarks plays an essential role as hidden components. The {\it KPM} may also be produced during the formation and decay of neutron stars.

astro-ph.HE

K-K-pp - an important gateway toward multi-kaonic nuclei

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.

nucl-ex

Deduction of $M(Sigma pi)$ for $Lambda(1405)$ with mixed $T_{ Sigma pi leftarrow K^-p} and T_{ Sigma pi leftarrow Sigmapi}$ from Hemingway's data

We formulated the $Lambda(1405)$ (abbreviated as $Lambda^*$) $rightarrow (Sigmapi)^0$ invariant-mass spectra produced in the $K^- + p rightarrow Sigma^+ (1660) + pi^-$, followed by $Sigma^+ (1660) rightarrow Lambda(1405) + pi^+ rightarrow Sigmapi + pi^+$, processes at $p(K^-) = 4.2$ GeV/$c$, in which both the incident channel for a quasi-bound $K^-p$ state and its decay process to $(Sigma pi)^0$ were taken into account realistically. We calculated $M(Sigma pi)$ spectral shapes using mixed transition matrices, $T_{21} = T_{ Sigmapi leftarrow K^-p}$ and $T_{22} = T_{ Sigma pi leftarrow Sigma pi}$, for various theoretical models involving $Lambda^*$. The asymmetric spectra were compared to old experimental data of Hemingway, and it was found that the mixing of the two channels, written as $(1-f) , T_{21} + f, T_{22}$, gave a better result than considering the individual channels, yielding $f = 0.376_{-0.019}^{+0.021}$, $M(Lambda^*) = 1406.6_{-3.3}^{+3.4}$ MeV/$c^2$ and $Gamma = 70 pm 2$ MeV, nearly consistent with the 2014 PDG values.

hep-ph

Observation of Rapid Change of Crystalline Structure during the Phase Transition of the Palladium-Hydrogen System

We performed an X-ray diffraction experiment while palladium bulk absorbed and desorbed hydrogen to investigate the behavior of the crystalline lattice during the phase transition between the $α$ phase and $β$ phase. Fast growth of $β$ phase was observed around x=0.1 and x=0.45 of PdH$_x$. In addition, slight compression of the lattice at high hydrogen concentration and increase in the lattice constant and the line width of the $α$ phase after a cycle of absorption and desorption of hydrogen was observed. These behavior correlated with the change in the sample length, which may infer that the change in shape was related to the phase transition.

cond-mat.mtrl-sci

Search for the deeply bound $K^-pp$ state from the semi-inclusive forward-neutron spectrum in the in-flight $K^-$ reaction on helium-3

An experiment to search for the $K^-pp$ bound state was performed via the in-flight $^3$He($K^-,n)$ reaction using 5.3 $\times$ $10^9$ kaons at 1 GeV/$c$ at the J-PARC hadron experimental facility. In the semi-inclusive neutron missing-mass spectrum at $θ_{n}^{lab}=0^\circ$, no significant peak was observed in the region corresponding to $K^-pp$ binding energy larger than 80 MeV, where a bump structure has been reported in the $Λp$ final state in different reactions. Assuming the state to be isotropically decaying into $Λp$, mass-dependent upper limits on the production cross section were determined to be 30--180, 70--250, and 100--270 $μ$b/sr, for the natural widths of 20, 60, and 100 MeV, respectively, at 95\% confidence level.

nucl-ex

Strong binding and shrinkage of single and double kbar~nuclear systems (K^-pp, K^-ppn, K^-K^-p and K^-K^-pp) predicted by Faddeev-Yakubovsky calculations

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 changes by varying the KbarN interaction in the dense nuclear medium are given. Using the Lambda(1405) ansatz with a PDG mass of 1405 MeV/ c^2 for K^-p, the following ground-state binding energies together with the wave functions were obtained: 51.5 MeV ( K^ - pp ), 69 MeV ( K^ - ppn), 30.4 MeV ( K^ - K^ - p ) and 93 MeV ( K^ -K^ - pp ), which are in good agreement with previous results of variational calculation based on the Akaishi-Yamazaki coupled-channel potential. The K^ - K^ - pp state has a significantly increased density where the two nucleons are located very close to each other, in spite of the inner NN repulsion. Relativistic corrections on the calculated non-relativistic results indicate substantial lowering of the bound-state masses, especially of K^-K^-pp , toward the kaon condensation regime. The fact that the recently observed binding energy of K^-pp is much larger (by a factor of 2) than the originally predicted one may infer an enhancement of the KbarN interaction in dense nuclei by about 25 %, possibly due to chiral symmetry restoration. In this respect some qualitative accounts are given based on "clearing QCD vacuum" model of Brown, Kubodera and Rho.

nucl-th

Theoretical analysis of Lambda(1405) --> (Sigma pi)^0 mass spectra produced in p+p --> p + Lambda(1405) + K^+ reactions

We formulated the Lambda(1405) (abbreviated as Lambda^*) --> (Sigma pi)^0 invariant-mass spectra produced in p+p --> p + Lambda^* + K^+ reactions, in which both the incident channel for a quasi-bound K^-p state and its decay process to (Sigma pi)^0 were taken into account realistically. We calculated M(Sigma pi) spectral shapes for various theoretical models for Lambda^*. They are asymmetric and skewed, and were compared with recent experimental data of HADES, yielding M(Lambda^*) = 1405 -9 +11 MeV/c^2 and Gamma = 62 +- 10 MeV, where the interference effects of the Kbar N-Sigma pi resonance with I= 0 and 1 Sigma pi continuum are considered. The nearly isotropic proton distribution observed in DISTO and HADES is ascribed to a short collision length in the production of Lambda^*, which justifies the high sticking mechanism of Lambda^* and the participating proton into K^-pp.

nucl-th

The K1.8BR spectrometer system at J-PARC

A new spectrometer system was designed and constructed at the secondary beam line K1.8BR in the hadron hall of J-PARC to investigate $\bar K N$ interactions and $\bar K$-nuclear bound systems. The spectrometer consists of a high precision beam line spectrometer, a liquid $^3$He/$^4$He/D$_2$ target system, a Cylindrical Detector System that surrounds the target to detect the decay particles from the target region, and a neutron time-of-flight counter array located $\sim$15 m downstream from the target position. Details of the design, construction, and performance of the detector components are described.

physics.ins-det

Deformation of Palladium Plates by a Small Stress during Hydrogen Absorption and Desorption

We observed an unexpected bending of a horizontally held palladium plate at 150$^{\circ}$C under a small external shearing stress. The deformation was fastest at the nominal composition of PdH$_{\rm 0.1-0.2}$, which is in the $α+β$ phase. We also observed that a plate warped back and forth during a cycle of absorption and desoprtion of hydrogen when it was hung vertically, which does not have a reasonable explanation.

cond-mat.mtrl-sci

New Way to Produce Dense Double-Antikaonic Dibaryon System, \bar{K}\bar{K} NN, through Lambda(1405)-Doorway Sticking in p+p Collisions

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 K^-K^-pp is a dense object, as predicted.

nucl-th

Experimental confirmation of the Lambda(1405) Ansatz from resonant formation of a K-p quasi-bound state in K- absorption by 3He and 4He

The Sigma-pi invariant-mass spectra in the resonant capture of K- at rest in 4He, 3He and d are calculated by a coupled-channel procedure for a K-p quasi-bound state of an arbitrary chosen mass (M) and width (Gamma). A chi2 analysis of old 4He bubble chamber data shows a dominance of the s-orbit absorption, and yielded M = 1405.5 ^(+1.4)_(-1) MeV/c2 and Gamma = 26 ^(+4)_(-3) MeV, where a possible population of Sigma0(1385) and also a small p-orbit capture contribution are taken into account. This result confirms the Lambda(1405) ansatz, whereas recent chiral-SU(3) predictions (M ~ 1420 MeV/c2) are excluded. A more stringent test by using a 3He target is proposed .

nucl-th

Single-pole nature of Lambda (1405) and structure of K-pp

We have studied the structure of K- pp by solving this system in a variational treatment, starting from ansatz that Lambda(1405) is a K-p quasi-bound state, Lambda* with mass 1405 MeV/c2. The structure of K-pp reveals a molecular feature, namely, the K- in an "atomic center", Lambda*, plays a key role in producing strong covalent bonding with the other proton. Deeply bound Kbar nuclear systems are formed by this "super-strong" nuclear force due to migrating real bosons, Kbar, a la Heitler-London-Heisenberg, which overcompensates the stiff nuclear incompressibility. Theoretical background of the Lambda (1405) ansatz is discussed in connection with the double-pole picture of Lambda (1405) based on chiral SU(3) dynamics. Detailed analysis reveals single-pole nature of the observable Lambda (1405). There are two kinds of Sigma pi invariant masses experimentally observable, the usual T22 invariant mass and the conversion T21 invariant mass. It is of vital importance to determine whether the Lambda* mass is 1405 MeV or 1420 MeV. The T21 invariant mass from K- absorption at rest in deuteron can provide decisive information about this Lambda* mass problem.

nucl-th

Interplay between Yukawa and Tomonaga in the Birth of Mesons

Light is shed on the early stage in the birth of Yukawa's meson theory, particularly on the interplay between Yukawa and Tomonaga in 1933. The discovery of the muon by Nishina' group in 1937 is also reviewed. It is pointed out that Heisenberg's attempt to explain the nuclear force in terms of the Heitler-London scheme, overcome by Yukawa and abandoned since then, is now being revived as a mechanism for a super strong nuclear force caused by a migrating real Kbar meson.

hep-ph

The Quest for Pionic and Kaonic Nuclear Bound Systems Following Yukawa and Tomonaga

After sketching some historical events related to Yukawa and Tomonaga concerning the birth of mesons, the author describes recent developments in the spectroscopy of pion-nucleus bound states via "pion-transfer" reactions. The role of pions as Nambu-Goldstone bosons in nuclear media is emphasized by recently obtained experimental evidence for the partial restoration of chiral symmetry breaking. New light is shed on Kbar mesons, which play a unique role in forming dense nuclear systems. The basic unit, K- pp, is predicted to possess a molecular structure with quasi-Lambda(1405) as an "atomic constituent". We find here "super strong nuclear force" produced by a migrating real Kbar meson in the Heitler-London-Heisenberg scheme in place of the normal nuclear force mediated by Yukawa's virtual mesons.

nucl-ex

The basic K nuclear cluster K- pp and its enhanced formation in the p + p -> K+ + X reaction

We have studied the structure of K- pp nuclear cluster comprehensively by solving this three-body system exactly in a variational method starting from the Ansatz that the Lambda(1405) resonance (Lambda*) is a K-p bound state. We have found that our original prediction for the presence of K-pp as a compact bound system with M = 2322$ MeV/c2, B = 48 MeV and Gamma = 60 MeV remains unchanged by varying the Kba-rN and NN interactions widely as far as they reproduce Lambda(1405). 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 have shown that the elementary process, p + p -> K+ + Lambda* + p, which occurs in a short impact parameter and with a large momentum transfer (Q ~ 1.6$ GeV/c), leads to unusually large self-trapping of Lambda* by the participating proton, since the Lambda*-p system exists as a compact doorway state propagating to K- pp (R{Lambda*-p} ~ 1.67 fm).

nucl-th

Super strong nuclear force caused by migrating Kbar mesons - Revival of the Heitler-London-Heisenberg scheme in kaonic nuclear clusters

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 by mediating virtual pions. We have shown that the elementary process, p + p --> K+ + Lambda* + p, which occurs in a short impact parameter and with a large momentum transfer, leads to unusually large self-trapping of Lambda* by the involved proton, since the Lambda*-p system exists as a compact doorway state propagating to K-pp.

nucl-th

Emission spectra and invariant masses of Lambda and p in the stopped-K-NN absorption process in 4He and 6Li

We have calculated the emission spectra of Y and N and invariant masses of YN pairs in the direct K-NN --> YN absorption process at rest in 4He and light nuclei in order to provide theoretical tools for correct interpretations of experimental data with or without invoking kaonic nuclear bound states. All the momentum distributions are broad with widths around 150-200 MeV/c (except for the case of 6Li target), while the partial invariant mass of each YN pair has a peak around 2310-2330 MeV/c2. We argue against the interpretations of stopped-K- experimental data of KEK and FINUDA by Oset and Toki and by Magas, Oset, Ramos and Toki.

nucl-ex

Enhanced formation of a dense Kbar nuclear cluster K^- pp in pp collisions - Lambda*-p doorway dominance

We have found theoretically that the elementary process, p + p to K+ + Lambda(1405) + p, which occurs in a short impact parameter (around 0.2 fm) and with a large momentum transfer (Q ~ 1.6 GeV/c), leads to unusually large self-trapping of Lambda(1405) by the projectile proton, when a Lambda* -p system exists as a dense bound state (size ~ 1.0 fm) propagating to K^-pp. The seed, called "Lambda*-p doorway", is expected to play an important role in the (p, K*) type reactions and heavy-ion collisions to produce various Kbar nuclear clusters.

nucl-th