arXiv subjects

Ehoud Pazy

Publications and source records attributed to Ehoud Pazy.

9 recordsLinked to original sources

arXiv2026

Scaling Laws for Three-Body Nuclear Contacts

Three-nucleon short-range correlations (3N-SRCs) represent one of the least understood manifestations of short-range nuclear dynamics. We investigate these correlations within the generalized contact formalism and compute three-body nuclear contacts using a mean-field description of the long-range component of the nuclear wave function. These contacts quantify the probability of finding correlated nucleon triplets at short distances and provide a natural extension of the contact formalism beyond nucleon pairs. We find that the $^{3}$He and $^{3}$H contacts exhibit significant isospin-symmetry breaking, analogous to that observed previously for two-body contacts. Motivated by the semi-empirical mass formula, we derive a simple scaling relation for three-body contacts and show that it accurately reproduces the calculated values across medium-mass and heavy nuclei. Our results reveal a systematic dependence of 3N-SRCs on nuclear mass and composition, suggesting that three-body contacts obey universal scaling patterns closely analogous to those governing short-range-correlated nucleon pairs.

nucl-th↗

arXiv2024

The Relative Abundance of Correlated Spin-zero Nucleon Pairs

We utilize the generalized contact formalism in conjunction with the Woods-Saxon mean-field description of the long-range part of the nuclear wave function to assess the relative prevalence of short-range correlation pairs within atomic nuclei. We validate our approach by fitting experimental charge density results and electron scattering experiments to a very good agreement. Applying our model, we calculate the spin-zero short-range correlations contact ratios. Interestingly, for nuclei with $A>50$, we observe a notable dependence on the neutron-to-proton ratio $N/Z$. Specifically, the probability per nucleon to find neutron-neutron pairs increases, while that of proton-proton pairs decreases, whereas the probability of finding neutron-proton pairs remains relatively constant. To interpret this isospin symmetry breaking effect, we employ a simple model based on generalized Levinger constants, linking it to differences in nuclear proton and neutron radii.

nucl-th↗

arXiv2022

The Entanglement Entropy between Short Range Correlations and the Fermi Sea in Nuclear Structure

We calculate the nuclear structure orbital entanglement entropy of short range correlations (SRC) based on the nuclear scale separation. Specifically, the entanglement between the SRC orbitals and the rest of the system. It should be stressed that this is a single nucleon not a pair entanglement entropy between the proton and neutron. The entanglement arises from the probability for a nucleon to occupy a momentum state above the Fermi momentum. We separate the momentum space of the nucleus into two parts such that nucleons can occupy the meanfield part of the wave function, i.e. Fermi sea (FS) and separately the high-momentum SRC part. The orbital entropy we obtain is between these two parts where we essentially define two momentum subspaces, one containing all the low momentum FS states and the other the high-momentum part as a SRC "orbital" state. For the calculation we employ the decoupling of low and high-momenta which was established by the similarity normalization group the SRC is viewed as a further "orbital" which can be multiply occupied. Since the probability of the occupation of a single SRC is given by the nuclear contact we are able to obtain a simple general expression of the orbital entanglement entropy for SRC by employing the generalized contact formalism. This general formula for the SRC orbital entanglement entropy of a nuclear structure in terms of the nuclear contact, allows us to obtain the scaling of the entropy in terms the mass number, $A$. We find that, unlike the entanglement entropy of many quantum systems which scales with the surface area, the orbital entanglement entropy associated with the SRC in large nuclei is linearly dependent on $A$, i.e., it is shown to be extensive.

nucl-th↗

arXiv2020

The fractal geometry and the mapping of Efimov states to Bloch states

Efimov states are known to have a discrete real space scale invariance, working in momentum space we identify the relevant discrete scale invariance for the scattering amplitude defining its Weierstrass function as well. Through the use of the mathematical formalism for discrete scale invariance for the scattering amplitude we identify the scaling parameters from the pole structure of the corresponding zeta function, it's zeroth order pole is fixed by the Efimov physics. The corresponding geometrical fractal structure for Efimov physics in momentum space is identified as a ray across a logarithmic spiral. This geometrical structure also appears in the physics of atomic collapse in the relativistic regime connecting it to Efimov physics. Transforming to logarithmic variables in momentum space we map the three-body scattering amplitude into Bloch states and the ladder of energies of the Efimov states are simply obtained interms of the Bohr-Sommerfeld quantization rule. Thus through the mapping the complex problem of three-body short range interaction is transformed to that of a non-interacting single particle in a discrete lattice.

nucl-th↗

arXiv2017

Electromagnetic characteristics of $A \leq 3$ physical and lattice nuclei

We analyze the quark-mass dependence of electromagnetic properties of two and three-nucleon states. To that end, we apply the pionless effective field theory to experimental data and numerical lattice calculations which simulate QCD at pion masses of 450~MeV and 806~MeV. At the physical pion mass, we postdict the magnetic moment of helium-3, $\mu_{^3He}=-2.13~$nNM, and the magnetic polarizability of deuterium, $\beta_D=7.33~10^{-2}~$fm$^3$. Magnetic polarizabilities of helium-3, $\beta_{^3He}=9.7~10^{-4}~$fm$^3$, and the triton, $\beta_{^3H}=8.2~10^{-4}~$fm$^3$, are predictions. Postdictions of the effective theory for the magnetic moments are found consistent with QCD simulations at 806~MeV pion mass while our EFT result $\beta_D=2.92~10^{-2}~$fm$^3$ was not extracted from the lattice. The deuteron would thus be relatively pliable compared to a three-nucleon state for which we postdict $\beta_{^3H}=3.9~10^{-5}~$fm$^3$. At $m_\pi=450~$MeV, the magnetic moment of the triton is predicted, $\mu_{^3He}=-2.15(5)~$nNM, based on a conjecture of its binding energy, $B_{^3H}\cong 30$~MeV. For all three pion masses, we compare the point-charge radii of the two and three-nucleon bound states. The sensitivity of the electromagnetic properties to the Coulomb interaction between protons is studied in anticipation of lattice calculations with dynamical QED.

nucl-th↗

arXiv2016

Short range correlations - The important role of few-body dynamics in many-body systems

For many-body systems with short range interaction a series of relations were derived connecting many properties of the system to the dynamics of a closely packed few-body subsystems. Some of these relations were experimentally verified in ultra cold atomic gases. Here we shall review the implications of these developments on our understanding of nuclear one and two-body momentum distributions, and on the electron scattering Coulomb sum rule.

nucl-th↗

arXiv2013

Considerations for a cosmological extension of modified Newtonian dynamics connections to conformal gravity and Rindler force theories

Modified Newtonian dynamics (MOND) can be obtained by modifying the entropic formulation of gravity, this is achieved by considering the quantum statistical nature of the degrees of freedom on the holographic screen. Through this frame work, we find some constraints on a cosmological extension for MOND, with no additional auxiliary fields. The connections between MOND to conformal gravity and Rindler force gravity are examined. These two alternative gravity theories are subsequently considered as possible cosmological extensions of MOND.

gr-qc↗

arXiv2005

Quantum Computing with Spin Qubits Interacting Through Delocalized Excitons: Overcoming Hole Mixing

As a candidate scheme for controllably coupled qubits, we consider two quantum dots, each doped with a single electron. The spin of the electron defines our qubit basis and trion states can be created by using polarized light; we show that the form of the excited trion depends on the state of the qubit. By using the Luttinger-Kohn Hamiltonian we calculate the form of these trion states in the presence of light-heavy hole mixing, and show that they can interact through both the Förster transfer and static dipole-dipole interactions. Finally, we demonstrate that by using chirped laser pulses, it is possible to perform a two-qubit gate in this system by adiabatically following the eigenstates as a function of laser detuning. These gates are robust in that they operate with any realistic degree of hole mixing, and for either type of trion-trion coupling.

quant-ph↗

arXiv2003

Photocurrent in conjugated polymers

Nonlinear photocurrent carriers in conjugated polymers, such as polarons, bipolarons and solitons, are considered at low photon energies where a tunnelling process is necessary. We show that polarons usually dominate the photocurrent I due to a novel electric field assisted tunnelling for which ln(I) ~ -E^{-2/3}. For near degenerate polymers an electric field E which exceeds the confinement potential and frequencies above twice the soliton energy, soliton tunnelling is favored. Photocurrent data can then be used to identify the remarkable phenomenon of soliton conduction.

cond-mat↗