arXiv subjects

Akshay Vaghani

Publications and source records attributed to Akshay Vaghani.

4 recordsLinked to original sources

arXiv2018

Fate of the neutron-deuteron virtual state as an Efimov level

The emergence of Efimov levels in a three-body system is investigated near the unitarity limit characterized by resonating two-body interaction. No direct evidence of Efimov levels is seen in the three-nucleon system since the triton is the only physical bound state. We provide a model-independent analysis of nucleon-deuteron scattering at low energy by formulating a consistent effective field theory. We show that virtual states evolve into shallow bound states, which emerge as excited triton levels as we drive the system towards unitarity. Even though we consider this specific system, our results for the emergence of the Efimov levels are universal.

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arXiv2018

Radiative 3He-alpha reaction in Halo Effective Field Theory

In this work we study the radiative capture of ${\rm {}^3He}$ on ${\rm {}^4He}$ within the halo effective field theory (EFT) framework. At leading order the capture amplitude comprises the initial state $s$-wave strong and Coulomb interactions summed to all orders. At the same order in the expansion, leading two-body currents contribute as well. We find delicate cancelations between the various contributions, and the two-body current contributions can be replaced by appropriately enhancing the asymptotic normalizations of the $^7$Be ground and first excited state wave functions. The next-to-leading order corrections come from the $s$-wave shape parameter and the pure Coulomb $d$-wave initial state interactions. We fit the EFT parameters to available scattering data and most recent capture data. Our zero-energy astrophysical $S$-factor estimate, $S_{34}\sim 0.55$ keV b, is consistent within error bars with the average in the literature.

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arXiv2015

Electromagnetic form factors of one neutron halos with spin 1/2+ ground state

The electromagnetic form factors for single neutron halo nuclei Be-11, C-15 and C-19 are calculated. The calculations are performed in halo effective field theory (EFT) where the halo nuclei are approximated as made of a single neutron and a core. The form factors depend on the single neutron separation energy, the s-wave neutron-core scattering effective range and a two-body current. The EFT expressions are presented to leading order for C-15 and next-to-leading order for Be-11 and C-19.

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arXiv2012

Radiative Neutron Capture on Carbon-14 in Effective Field Theory

The cross section for radiative capture of neutron on carbon-14 is calculated using the model-independent formalism of halo effective field theory. The dominant contribution from E1 transition is considered, and the cross section is expressed in terms of elastic scattering parameters of the effective range expansion. Contributions from both resonant and non-resonant interaction are calculated. Significant interference between these leads to a capture contribution that deviates from simple Breit-Wigner resonance form.

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