arXiv subjects

T. Mizutani

Publications and source records attributed to T. Mizutani.

18 recordsLinked to original sources

arXiv2025

Indexing current-voltage characteristics using a hash function

Differentiating between devices of the same size is essential for ensuring their reliability. However, identifying subtle differences can be challenging, particularly when the devices share similar characteristics, such as transistors on a wafer. To address this issue, we propose an indexing method for current-voltage characteristics that assigns proximity numbers to similar devices. Specifically, we demonstrate the application of the locality-sensitive hashing (LSH) algorithm to Coulomb blockade phenomena observed in PMOSFETs and nanowire transistors. In this approach, lengthy data on current characteristics are replaced with hashed IDs, facilitating identification of individual devices, and streamlining the management of a large number of devices.

cond-mat.mes-hall↗

arXiv2013

Faddeev-Chiral Unitary Approach to the $K^- d$ scattering length

Our earlier Faddeev three-body study in the $K^-$-deuteron scattering length, $A_{K^-d}$, is revisited here in the light of the recent developments in two fronts: {\it (i)} the improved chiral unitary approach to the theoretical description of the coupled $\Kbar N$ related channels at low energies, and {\it (ii)} the new and improved measurement from SIDDHARTA Collaboration of the strong interaction energy shift and width in the lowest $K^-$-hydrogen atomic level. Those two, in combination, have allowed us to produced a reliable two-body input to the three-body calculation. All available low-energy $K^-p$ observables are well reproduced and predictions for the $\Kbar N$ scattering lengths and amplitudes, $(πΣ)^\circ$ invariant-mass spectra, as well as for $A_{K^-d}$ are put forward and compared with results from other sources. The findings of the present work are expected to be useful in interpreting the forthcoming data from CLAS, HADES, LEPS and SIDDHARTA Collaborations.

hep-ph↗

arXiv2009

Charmed baryon resonances with heavy-quark symmetry

We study charmed baryon resonances that are generated dynamically from a coupled-channel unitary approach that implements heavy-quark symmetry. Some states can already be identified with experimental observations, such as $Λ_c(2595)$, $Λ_c(2660)$, $Σ_c(2902)$ or $Λ_c(2941)$, while others need a compilation of more experimental data as well as an extension of the model to include higher order contributions. We also compare our model to previous SU(4) schemes.

hep-ph↗

arXiv2009

The s-wave charmed baryon resonances from a coupled-channel approach with heavy quark symmetry

We study charmed baryon resonances which are generated dynamically within a unitary meson-baryon coupled channel model that treats the heavy pseudoscalar and vector mesons on equal footing as required by heavy-quark symmetry. It is an extension of recent SU(4) models with t-channel vector meson exchanges to a SU(8) spin-flavor scheme, but differs considerably from the SU(4) approach in how the strong breaking of the flavor symmetry is implemented. Some of our dynamically generated states can be readily assigned to recently observed baryon resonances, while others do not have a straightforward identification and require the compilation of more data as well as an extension of the model to d-wave meson-baryon interactions and p-wave coupling in the neglected s- and u-channel diagrams. Of several novelties, we find that the Lambda_c(2595), which emerged as a ND quasi-bound state within the SU(4) approaches, becomes predominantly a ND* quasi-bound state in the present SU(8) scheme.

hep-ph↗

arXiv2008

Chiral SU(3) Bethe Salpeter Model: Extension to SU(6) and SU(8) Spin-Flavor Symmetries

Consistent SU(6) and SU(8) spin-flavor extensions of the SU(3) flavor Weinberg-Tomozawa (WT) meson-baryon chiral Lagrangian are constructed, which incorporate vector meson degrees of freedom. In the charmless sector, the on-shell approximation to the Bethe-Salpeter (BS) approach successfully reproduces previous SU(3) WT results for the lowest-lying s--wave negative parity baryon resonances. It also provides some information on the dynamics of heavier ones and of the lightest d-wave negative parity resonances, as e.g. the Lambda(1520). For charmed baryons the scheme is consistent with heavy quark symmetry, and our preliminary results in the strangeness-less charm C=+1 sector describe the main features of the three-star J^P=1/2^- Lambda_c(2595) and J^P=3/2^- Lambda_c(2625) resonances. We also find a second broad J^P=1/2^- state close to the Lambda_c(2595)

hep-ph↗

arXiv2007

Resonances in chiral unitary approaches

The extension of chiral theories to the description of resonances, via the incorporation of unitarity in coupled channels, has provided us with a new theoretical perspective on the nature of some of the observed excited hadrons. In this contribution some of the early achievements in the field of baryonic resonances are reviewed, the recent evidence of the two-pole nature of the Lambda(1405) is discussed and results on charmed baryon resonances are presented.

nucl-th↗

arXiv2006

D Mesons in Nuclear Matter: A DN Coupled-Channel Equations Approach

A set of coupled two-body scattering equations is solved for the DN system embedded in an iso-symmetric nuclear matter. The in-medium behavior of charmed D mesons: (D^+,D^0), is investigated from the self-consistent solution within this scheme. The effective meson-baryon Lagrangian in charm quantum number one sector, the key ingredient in the present study, is adopted from a recent model by Hofmann and Lutz which has aimed at combining the charmed meson degree of freedom in a consistent manner with chiral unitary models. After a critical examination, the original model is modified in several important aspects, such as the method of regularization, in order to be more consistent and practical for our objective. The resultant interaction is used to reproduce the position and width of the s-wave Λ_c(2593) resonance in the isospin zero DN channel. In the isospin one channel, it generates a rather wide resonance at \~2770 MeV. The corresponding in-medium solution is then sought by incorporating Pauli blocking and the D- and π-meson dressing self-consistently. At normal nuclear matter density, the resultant Λ_c (2593) is found to stay narrow and shifted at a lower energy, while the I=1 resonance is lowered in position as well and broadened considerably. The possible implication of our findings on the J/Ψsuppression, etc. in relativistic heavy ion collisions is briefly discussed.

hep-ph↗

arXiv2003

Low energy Kbar N interactions and Faddeev calculation of the K- d scattering length in isospin and particle bases

$\Kbar N$ interactions are investigated {\it via} an effective non-linear chiral meson-baryon Lagrangian. The adjustable parameters are determined by a fitting procedure on the $K^-p$ threshold branching ratios and total cross-section data for $p^{lab}_K\le$ 250 MeV/c. We produce predictions for the $Σπ$ mass spectrum, and scattering lenghts $a_{K^-p}$, $a_n(K^-n \to K^-n)$, $a_n0(\Kbar0 n \to \Kbar0 n)$, and $a_{ex}(K^-p \to \Kbar0 n)$. The $\Kbar N$ amplitudes thus obtained, as well as those for other two-body channels ($πN$, $NN$, and $YN$) are used as input to predict the scattering length $A_{K^-d}$, for which we have devised a relativistic version of the three-body Faddeev equations. Results for all two- and three-body coupled channels are reported both in isospin and particle bases. All available $\Kbar N$ data are well reproduced and our best results for the $K^-p$ and $K^-d$ scattering lenghts are $a_{K^-p} = (-0.90 + i 0.87) fm$ and $A_{K^-d} = (-1.80 + i 1.55) fm$.

nucl-th↗

arXiv2002

Fermiology and superconductivity studies on the non-tetrachalcogenafulvalene structured organic superconductor beta-(BDA-TTP)_2SbF_6

The quantum oscillatory effect and superconductivity in a non-tetrachalcogenafulvalene (TCF) structure based organic superconductor beta-(BDA-TTP)_2SbF_6 are studied. Here the Shubnikov-de Haas effect (SdH) and angular dependent magnetoresistance oscillations (AMRO) are observed. The oscillation frequency associated with a cylindrical Fermi surface is found to be about 4050 tesla, which is also verified by the tunnel diode oscillator (TDO) measurement. The upper critical field Hc2 measurement in a tilted magnetic field and the TDO measurement in the mixed state reveal a highly anisotropic superconducting nature in this material. We compared physical properties of beta-(BDA-TTP)_2SbF_6 with typical TCF structure based quasi two-dimensional organic conductors. A notable feature of beta-(BDA-TTP)_2SbF_6 superconductor is a large value of effective cyclotron mass m_c^*=12.4+/1.1 m_e, which is the largest yet found in an organic superconductor. A possible origin of the enhanced effective mass and its relation to the superconductivity are briefly discussed.

cond-mat.str-el↗

arXiv2002

Three-Body approach to the K^- d Scattering Length in Particle Basis

We report on the first calculation of the scattering length A_{K^-d} based on a relativistic three-body approach where the two-body input amplitudes coupled to the Kbar N channels have been obtained with the chiral SU(3) constraint, but with isospin symmetry breaking effects taken into account. Results are compared with a recent calculation applying a similar set of two-body amplitudes,based on the fixed center approximation, considered as a good approximation for a loosely bound target, and for which we find significant deviations from the exact three-body results. Effects of the hyperon-nucleon interaction, and deuteron $D$-wave component are also evaluated.

nucl-th↗

arXiv1999

K -> pi pi and a light scalar meson

We explore the Delta-I= 1/2 rule and epsilon'/epsilon in K -> pi pi transitions using a Dyson-Schwinger equation model. Exploiting the feature that QCD penguin operators direct K^0_S transitions through 0^{++} intermediate states, we find an explanation of the enhancement of I=0 K -> pi pi transitions in the contribution of a light sigma-meson. This mechanism also affects epsilon'/epsilon.

nucl-th↗

arXiv1998

Effective Lagrangian Study of $γp \to K^+ Λ$ (spin 3/2 resonances and their off-shell effects)

The purpose of the present discussion is to supplement the talk, by B.~Saghai at this workshop, on the study of the electromagnetic production of strangeness on the nucleon based upon effective Lagrangian methods. Here we focus on the proper treatment of the spin 3/2 resonances and their associated effects due to the spin 1/2 component of the corresponding fields when they are {\it off the mass shell}.

nucl-th↗

arXiv1998

Heavy-to-light form factors in the quark model with heavy propagators

We calculate the heavy-to-light form factors in the relativistic quark model with heavy infrapropagators. Their q^2-dependence in the physical region is defined by two parameters: the "infrared" parameter νcharacterizing the infrared behavior of the heavy quark and the mass difference of the heavy meson and heavy quark E=m_H-M_Q. It is found that the values of the D\to K(K^*) and D\to π(ρ) form factors at q^2=0 are in excellent agreement with the available experimental data and other approaches whereas these values for B\to π(ρ) transitions are found to be larger than those of several other models. The obtained form factors are used to calculate the widths of the semileptonic decays of B and D mesons. The comparison of our results with the available experimental data and other approaches is given

hep-ph↗

arXiv1997

Off-shell effects in the electromagnetic production of strangeness

Previous approaches to the photo- and electro-production of strangeness off the proton, based upon effective hadronic Lagrangians, are extended here to incorporate the so called off-shell effects inherent to the fermions with spin >= 3/2. A formalism for intermediate-state, spin 3/2, nucleonic and hyperonic resonances is presented and applied to the processes $γ+ p ---> K^{+} + Λ$, for $E_γ^{lab}$ <= 2.5 GeV, $e + p ---> e' + K^+ + Λ$, as well as the branching ratio for the crossed channel reaction $K^- + p ---> γ+ Λ$, with stopped kaons. The sensitivity, from moderate to significant, of various observables to such effects are discussed.

nucl-th↗

arXiv1997

The box anomaly and radiative decays of η(η')-mesons

We report on a confined quark model calculation of the transition form factors for the radiative decays of η(η')->γl^+l^- and η(η')->γπ^+π^-. The η-η' mixing angle θ_P is determined from the set of data on the electromagnetic η(η') decays. It is found that θ_P\sim -16.5. The analysis of the dipionic mass distribution in the decay η'->γπ^+π^- confirms the existence of a non-resonant contribution which is the box anomaly.

hep-ph↗

arXiv1995

Reaction γπ\to ππin a confined quark model

A confined quark model study in a couple of chirally anomalous processes is presented in comparison with effective meson Lagrangian approaches of various kind. The processes considered are π^0 \to γγand γ\to π^+ π^- π^0 (or the equivalent πγ\to ππ) for which there is a well-known low energy theorem relating the latter amplitude with the former one by a very simple algebraic relation in the zero energy (or chiral, or soft pion) limit. Our quark model naturally generates the so-called contact term in the amplitude for the second process, but with the opposite sign to what effective chiral meson models indicate. A reinterpretation of our vector pole contribution restores the consistency, however. While the first reaction is observed to serve in it calibrating various models, it is found difficult, based upon the quality of the existing data in the second reaction, to single out the best model, which appears indispensable for testing the validity of the above low energy theorem. Thus the proposed experiments and their analyses should aim at attaining an optimal accuracy.

hep-ph↗

arXiv1995

Self-energy of Heavy Quark

We demonstrate that to calculate the self-energy of a heavy quark in the heavy quark limit (or the heavy fermion limit in what is called the Baryon Chiral Perturbation Theory), the use of standard dimensional regularization provides only the quantum limit: opposite to the heavy quark (or classical) limit that one wishes to obtain. We thus devised a standard ultraviolet/infrared regularization procedure in calculating the one- and two-loop contributions to the heavy quark self-energy in this limit. Then the one-loop result is shown to provide the standard classical Coulomb self-energy of a static colour source that is linearly proportional to the untraviolet cutoff $Λ$. All the two-loop contributions are found to be proportional to $Λ\ln(Λ/λ)$ where $λ$ is the infrared cutoff. Often only the contribution from the bubble (light quarks, gluon and ghost) insertion to the gluon propagator has been considered as the $O(α_s)$ correction to the Coulomb energy to this order. Our result shows that other contributions are of the same magnitude, thus have to be taken into account.

hep-ph↗

arXiv1994

Heavy quark limit in the model with confined light quarks and infrared heavy quark propagators

We have studied the weak decay constants and the Isgur-Wise form factor of the B and D mesons in the heavy quark limit, by employing a relativistic quark confinement model. It is an attempt to improve our previous work within the same line of thinking, but by incorporating a couple of novel aspects. First, the infrared behavior of the heavy quark is considered by modifying its conventional propagator in terms of a single parameter $ν$. Second, the mass difference of the heavy meson and heavy quark: $E=m_H-M_Q$ has been included. It is found that the weak decay constants depend strongly on the mass difference E with a relatively mild $ν$ dependence. As for the Isgur-Wise function it is controlled more sensitively by the infrared parameter $ν$, leading to its suppression at maximum meson recoil.

hep-ph↗