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H. Morita

Publications and source records attributed to H. Morita.

At least 19 recordsLinked to original sources
arXiv2019

Hard particle spectra of galactic X-ray sources by relativistic magnetic reconnection in laser lab

Magnetic reconnection is a process whereby magnetic field lines in different directions "reconnect" with each other, resulting in the rearrangement of magnetic field topology together with the conversion of magnetic field energy into the kinetic energy (K.E.) of energetic particles. This process occurs in magnetized astronomical plasmas, such as those in the solar corona, Earth's magnetosphere, and active galactic nuclei, and accounts for various phenomena, such as solar flares, energetic particle acceleration, and powering of photon emission. In the present study, we report the experimental demonstration of magnetic reconnection under relativistic electron magnetization situation, along with the observation of power-law distributed outflow in both electron and proton energy spectra. Through irradiation of an intense laser on a "micro-coil", relativistically magnetized plasma was produced and magnetic reconnection was performed with maximum magnetic field 3 kT. In the downstream outflow direction, the non-thermal component is observed in the high-energy part of both electron and proton spectra, with a significantly harder power-law slope of the electron spectrum (p = 1.535 +/- 0.015) that is similar to the electron injection model proposed to explain a hard emission tail of Cygnus X-1, a galactic X-ray source with the same order of magnetization. The obtained result showed experimentally that the magnetization condition in the emitting region of a galactic X-ray source is sufficient to build a hard electron population through magnetic reconnection.

physics.plasm-ph↗
arXiv2014

Measurement of the 12C(e,e'p)11B Two-Body Breakup Reaction at High Missing Momentum Values

The five-fold differential cross section for the 12C(e,e'p)11B reaction was determined over a missing momentum range of 200-400 MeV/c, in a kinematics regime with Bjorken x > 1 and Q2 = 2.0 (GeV/c)2. A comparison of the results and theoretical models and previous lower missing momentum data is shown. The theoretical calculations agree well with the data up to a missing momentum value of 325 MeV/c and then diverge for larger missing momenta. The extracted distorted momentum distribution is shown to be consistent with previous data and extends the range of available data up to 400 MeV/c.

nucl-ex↗
arXiv2013

Nucleon momentum distributions, their spin-isospin dependence and short-range correlations

The nucleon momentum distribution $n_A(k)$ for $A=$2, 3, 4, 16, and 40 nuclei is systematically analyzed in terms of wave functions resulting from advanced solutions of the nonrelativistic Schrödinger equation, obtained within different many-body approaches. Particular attention is paid to the separation of the momentum distributions into the mean-field and short-range correlations (SRC) contributions. It is shown that at high values of the momentum $k$ the high-momentum components ($k\gtrsim 1.5-2$ fm$^{-1}$) of all nuclei considered are very similar, exhibiting the well-known scaling behavior with the mass number $A$, independently of the used many-body approach and the details of the bare $NN$ interaction. The number of $NN$ pairs in a given ($ST$) state, viz., ($ST$)=(10), (00), (01), and (11), and the contribution of these states to the nucleon momentum distributions are calculated. It is shown that, apart from the (00) state, which has very small effects, all other spin-isospin states contribute to the momentum distribution in a wide range of momenta. It is shown that that for all nuclei considered the momentum distributions in the states T=0 and T=1 exhibit at $k\gtrsim 1.5-2$ fm$^{-1}$ very similar behaviors, which represents strong evidence of the A-independent character of SRCs. The ratio $n_A(k)/n_D(k)$ is analyzed in detail stressing that in the SRC region it always increases with the momentum and the origin of such an increase is discussed and elucidated. The relationships between the one- and two-body momentum distributions, considered in a previous paper, are discussed and clarified, pointing out the relevant role played by the center-of-mass motion of a correlated pair in the (10) state. The relationship of the present approach with the many-body methods based upon low-momentum effective interactions is briefly discussed.

nucl-th↗
arXiv2011

Universality of nucleon-nucleon short-range correlations: two-nucleon momentum distributions in few-body systems

Using realistic wave functions, the proton-neutron and proton-proton momentum distributions in $^3He$ and $^4He$ are calculated as a function of the relative, $k_{rel}$, and center of mass, $K_{CM}$, momenta, and the angle between them. For large values of ${k}_{rel}\gtrsim 2\,\,fm^{-1}$ and small values of ${K}_{CM} \lesssim 1.0\,\,fm^{-1}$, both distributions are angle independent and decrease with increasing $K_{CM}$, with the $pn$ distribution factorizing into the deuteron momentum distribution times a rapidly decreasing function of $K_{CM}$, in agreement with the two-nucleon (2N) short range correlation (SRC) picture. When $K_{CM}$ and $k_{rel}$ are both large, the distributions exhibit a strong angle dependence, which is evidence of three-nucleon (3N) SRC. The predicted center-of-mass and angular dependence of 2N and 3N SRC should be observable in two-nucleon knock-out processes $A(e,e'pN)X$.

nucl-th↗
arXiv2010

Short range correlations and wave function factorization in light and finite nuclei

Recent BNL and Jlab data provided new evidence on two nucleon correlations (2NC) in nuclei. The data confirm the validity of the convolution model, describing the spectral function (SF) of a correlated pair moving in the mean field with high and low relative and center-of-mass (cm) momenta, respectively. The model is built assuming that the wave function (WF) of a nucleus A, describing a configuration where the cm momentum of a correlated pair is low and its relative momentum is high, factorizes into the product of the two-body WF and that of the A-2 system. Such a factorization has been shown to occur in nuclear matter (NM). Here it is shown that few-body systems exhibit factorization, which seems to be therefore a general property, to be reproduced also in studies of the WF of finite nuclei.

nucl-th↗
arXiv2008

Effects of Ground-State Correlations on High Energy Scattering off Nuclei: the Case of the Total Neutron-Nucleus Cross Section

With the aim at quantitatively investigating the longstanding problem concerning the effect of short range nucleon-nucleon correlations on scattering processes at high energies, the total neutron-nucleus cross section is calculated within a parameter-free approach which, for the first time, takes into account, simultaneously, central, spin, isospin and tensor nucleon-nucleon (NN) correlations, and Glauber elastic and Gribov inelastic shadowing corrections. Nuclei ranging from 4He to 208Pb and incident neutron momenta in the range 3 GeV/c - 300 GeV/c are considered; the commonly used approach which approximates the square of the nuclear wave function by a product of one-body densities is carefully analyzed, showing that NN correlations can play a non-negligible role in high energy scattering off nuclei.

nucl-th↗
arXiv2008

Lepton Scattering off Few-Nucleon Systems at Medium and High Energies

The interpretation of recent Jlab experimental data on the exclusive process A(e,e'p)B off few-nucleon systems are analyzed in terms of realistic nuclear wave functions and Glauber multiple scattering theory, both in its original form and within a generalized eikonal approximation. The relevance of the exclusive process 4He(e,e'p)^3H for possible investigations of QCD effects is illustrated.

nucl-th↗
arXiv2007

Interpretation of recent JLab results on quasi elastic (e,e'p) reactions off few-nucleon systems

Recent JLab experimental data on quasi elastic 3He(e,e'p)2H(pn) and 4He(e,e'p)3H processes are interpreted using an approach based upon realistic wave functions and Glauber multiple scattering theory within a generalized eikonal approximation (GEA). The results of a non factorized calculation of the left-right asymmetry A_{TL} of the process 3He(e,e'p)2H, obtained using the full covariant form of the electromagnetic operator, are also presented.

nucl-th↗
arXiv2007

Effects of correlations on the total neutron-Nucleus cross section at high energies

The total neutron-Nucleus cross section has been calculated within an approach which takes into account nucleon-nucleon correlations, Glauber multiple scattering and inelastic shadowing corrections. Nuclear targets ranging from 4He to 208Pb and neutron incident momentum ranging from 3 to 300 GeV/c, have been considered. Correlations have been introduced by two different approaches leading to the same results. The commonly used approximation, consisting in treating nuclear effects only by a product of one-body densities, is carefully analyzed and it is shown that the effects of realistic correlations resulting from modern nucleon-nucleon interactions and realistic correlations resulting from realistic nucleon-nucleon interactions and microscopic ground state calculation of nuclear properties cannot be disregarded.

nucl-th↗
arXiv2006

Hadron Propagation in Medium: the Exclusive Process A(e,e'p)B in Few-Nucleon Systems

The mechanism of propagation of hadronic states in the medium is a key point for understanding particle-nucleus and nucleus-nucleus scattering at high energies. We have investigated the propagation of a baryon in the exclusive process A(e,e'p)B in few-nucleon systems using realistic nuclear wave functions and Glauber multiple scattering theory both in its original form and within a generalized eikonal approximation. New results for the processes 3He(e,e'p)2H and 4He(e,e'p)3H are compared with data recently obtained at the Thomas Jefferson Laboratory (JLAB).

nucl-th↗
arXiv2006

A new realistic many-body approach for the description of high-energy scattering processes off complex nuclei

A linked cluster expansion for the calculation of ground state observables of nuclei with realistic interactions has been developed. Using the V8' potential the ground state energy, density and momentum distribution of complex nuclei have been calculated and found to be in good agreement with the results obtained within the Fermi Hyper Netted Chain, and Variational Monte Carlo approaches. Using the same cluster expansion, with wave function and correlations parameters fixed from the calculation of the ground-state observables, various high energy scattering processes off complex nuclei have been calculated taking final state interaction effects into account by means of the Glauber multiple scattering series.

nucl-th↗
arXiv2005

A Realistic Calculation of the Effects of Nucleon-Nucleon Correlations in High-Energy Scattering Processes Off Nuclei

A new linked cluster expansion for the calculation of ground state observables of complex nuclei with realistic interactions has been developed [1-3]; using the V8' potential [4] the ground state energy, density and momentum distribution of complex nuclei have been calculated and found to be in good agreement with the results of [5], obtained within the Fermi Hyper Netted Chain, and Variational Monte Carlo [6] approaches. Using the same cluster expansion, with wave function and correlations Realistic Calculation of the Effects of Nucleon-Nucleon Correlations in High-Energy Scattering Processes Off Nuclei parameters fixed from the calculation of the ground-state observables, the semi-inclusive reaction of type A(e,e'p)X has been calculated taking final state interaction effects into account within a Glauber type calculation as in Ref. [7]; the comparison between the resulting distorted and undistorted momentum distributions provides an estimate of the transparency of the nuclear medium to the propagation of the hit proton. The effect of color transparency has also been considered within the approach of [8,9]; it is shown that at high values of Q^2 finite formation time effects strongly reduce the final state interaction, consistently with the idea of a reduced interaction of the hadron produced inside the nucleus [10]. The total neutron-nucleus cross section at high energies has also been calculated [11] by considering the effects of nucleon-nucleon correlations, which are found to increase the cross section by about 10% in disagreement with the experimental data. The inclusion of inelastic shadowing effects of Refs. [12,13] decreases back the cross section, leading to a good agreement between experimental data and theoretical calculations.

nucl-th↗
arXiv2005

Ground-state energies, densities and momentum distributions in closed-shell nuclei calculated within a cluster expansion approach and realistic interactions

A linked cluster expansion suitable for the treatment of ground-state properties of complex nuclei, as well as of various particle-nucleus scattering processes, has been used to calculate the ground-state energy, density and momentum distribution of 16-O and 40-Ca using realistic interactions. First of all, a benchmark calculation for the ground-state energy has been performed using the truncated V8' potential, and consisting in the comparison of our results with the ones obtained by the Fermi Hypernetted Chain approach, adopting in both cases the same mean field wave functions and the same correlation functions. The results exhibited a nice agreement between the two methods. Therefore, the approach has been applied to the calculation of the ground-state energy, density and momentum distributions of 16-O and 40-Ca using the full V8' potential, finding again a satisfactory agreement with the results based on more advanced approaches where higher order cluster contributions are taken into account. It appears therefore that the cluster expansion approach can provide accurate approximations for various diagonal and non diagonal density matrices, so that it could be used for a reliable evaluation of nuclear effects in various medium and high energy scattering processes off nuclear targets. The developed approach can be readily generalized to the treatment of Glauber type final state interaction effects in inclusive, semi-inclusive and exclusive processes off nuclei at medium and high energies.

nucl-th↗
arXiv2003

Realistic Calculations of One- and Two-Hadron Emission Processes off Few- and Many-Body Nuclei

The exclusive electro-disintegration processes 2H(e,e'p)n, 3He(e,e'p)2H, 3He(e,e'p)pn, 3He(e,e'pp)n and 4He(e,e'p)3H have been calculated using realistic few-body wave functions and treating final state interaction (FSI) effects within a generalized eikonal approach. The semi-inclusive scattering A(e,e'p)X off complex nuclei has been analyzed using many-body wave functions for 16O and 40Ca, obtained within the framework of a linked cluster expansion and taking FSI into account by a Glauber-type approach. The effect of color transparency has also been included by considering the Finite Formation Time (FFT) that the hit hadron needs to reach its asymptotic physical state.

nucl-th↗
arXiv2003

Realistic calculations of correlations and final state interaction effects in the A(e,e'p)X process off complex nuclei

A linked cluster expansion for the calculation of ground state observables of complex nuclei with realistic interactions has been used to calculate the ground state energy, density and momentum distribution of 16O and 40Ca. Using the same cluster expansion and the wave function and correlation parameters obtained from the energy calculation, we have evaluated the semi inclusive reaction A(e,e'p)X taking final state interaction (FSI) into account by a Glauber type approach; the comparison between the distorted and undistorted momentum distributions provides an estimate of the transparency of the nuclear medium to the propagation of the hit proton. The effect of color transparency is also included by considering the Finite Formation Time (FFT) that the hit hadron needs to reach its asymptotic physical state.

nucl-th↗
arXiv2003

Finite Formation Time in Electro-Disintegration of Few-Body Nuclei

Inclusive and exclusive electro-disintegration of 2-H, 3-He and 4-He are calculated within an approach where, besides the final state interaction (FSI), also the finite formation time (FFT) of the hit hadron to its asymptotic physical state is taken into account.

nucl-th↗