arXiv subjects

Wael Elkamhawy

Publications and source records attributed to Wael Elkamhawy.

5 recordsLinked to original sources

arXiv2023

Entanglement in few-nucleon scattering events

We investigate the spin entanglement in few-nucleon scattering processes involving nucleons and deuterons. For this purpose, we consider the entanglement power introduced by Beane et al. We analyze different entanglement entropies as a basis to define the entanglement power of the strong interaction and calculate the corresponding entanglement powers for proton-neutron, neutron-deuteron, proton-deuteron, and deuteron-deuteron scattering. For the latter two processes, we also take into account the modification from the Coulomb interaction. In contrast to proton-neutron scattering, no universal low-energy features are evident in the spin entanglement in neutron-deuteron, proton-deuteron, and deuteron-deuteron scattering.

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arXiv2022

Weak decay of halo nuclei

We investigate the weak decay of one-neutron halo nuclei into the proton-core continuum, i.e., beta-delayed proton emission from the halo nucleus using a cluster effective field theory for halo nuclei. On the one hand, we calculate the direct decay into the continuum. On the other hand, we consider the case of resonant final state interactions between the proton and the core. We present our formalism and discuss the application to the decay of $^{11}$Be in detail. Moreover, we compare to recent experimental results for the branching ratio and resonance parameters. As another example, we consider the case of $^{19}$C and predict the branching ratio for beta-delayed proton emission.

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arXiv2022

Halo EFT for $^{31}$Ne in a spherical formalism

We calculate the electromagnetic properties of the deformed one-neutron halo candidate $^{31}$Ne using Halo Effective Field Theory (Halo EFT). In this framework, $^{31}$Ne is bound via a resonant $P$-wave interaction between the $^{30}$Ne core and the valence neutron. We set up a spherical formalism for $^{31}$Ne in order to calculate the electromagnetic form factors and the E1-breakup strength distribution into the $^{30}$Ne-neutron continuum at leading order in Halo EFT. The associated uncertainties are estimated according to our power counting. In particular, we assume that the deformation of the $^{30}$Ne core enters at next-to-leading order. It can be accounted for by including the $J^P=2^+$ excited state of $^{30}$Ne as an explicit field in the effective Lagrangian.

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arXiv2021

$\mathbfβ$-delayed proton emission from $\mathbf{^{11}}$Be in effective field theory

We calculate the rate of the rare decay $^{11}\text{Be}$ into $^{10}\text{Be} + p +e^- + \barν_e$ using Halo effective field theory, thereby describing the process of beta-delayed proton emission. We assume a shallow $1/2^+$ resonance in the $^{10}\text{Be}-p$ system with an energy consistent with a recent experiment by Ayyad et al. and obtain $b_p = 4.9_{-2.9}^{+5.6}\text{(exp.)}_{-0.8}^{+4.0}\text{(theo.)} \times 10^{-6}$ for the branching ratio of this decay, predicting a resonance width of $Γ_R = (9.0^{+4.8}_{-3.3}\text{(exp.)}^{+5.3}_{-2.2}\text{(theo.)})~\text{keV}$. Our calculation shows that the experimental branching ratio and resonance parameters of Ayyad et al. are consistent with each other. Moreover, we analyze the general impact of a resonance on the branching ratio and demonstrate that a wide range of combinations of resonance energies and widths can reproduce branching ratios of the correct order. Thus, no exotic mechanism (such as beyond the standard model physics) is needed to explain the experimental decay rate.

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arXiv2016

Consistent parameter fixing in the quark-meson model with vacuum fluctuations

We revisit the renormalization prescription for the quark-meson model in an extended mean-field approximation, where vacuum quark fluctuations are included. At a given cutoff scale the model parameters are fixed by fitting vacuum quantities, typically including the sigma-meson mass $m_σ$ and the pion decay constant $f_π$. In most publications the latter is identified with the expectation value of the sigma field, while for $m_σ$ the curvature mass is taken. When quark loops are included, this prescription is however inconsistent, and the correct identification involves the renormalized pion decay constant and the sigma pole mass. In the present article we investigate the influence of the parameter-fixing scheme on the phase structure of the model at finite temperature and chemical potential. Despite large differences between the model parameters in the two schemes, we find that in homogeneous matter the effect on the phase diagram is relatively small. For inhomogeneous phases, on the other hand, the choice of the proper renormalization prescription is crucial. In particular, we show that if renormalization effects on the pion decay constant are not considered, the model does not even present a well-defined renormalized limit when the cutoff is sent to infinity.

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