Low-energy $s$-wave scattering in weakly bound superfluid nuclei is strongly influenced by pairing correlations. In this work, we present an analytical study of low-energy $s$-wave quasiparticle scattering within the coordinate space Hartree-Fock-Bogoliubov framework using a schematic square-well model. Analytical expressions for the phase shift, elastic cross section, scattering length, and effective range are derived in a unified manner. We demonstrate that pairing correlations give rise to two distinct unitary limits, characterized by the divergence of the scattering length. One corresponds to the particle-like unitary limit, which persists even without pairing and is well described by the effective range expansion. The other is a pairing-induced hole-like unitary limit associated with quasiparticle resonances, leading to a breakdown of the effective range expansion. These results clarify the validity of the effective range expansion and highlight the essential role of resonance poles in describing low-energy $s$-wave quasiparticle scattering in superfluid nuclei.
Chiral $p_x\!\pm\! i p_y$ superfluidity in fermionic polar molecules offers a direct route to topological quantum matter with non-Abelian excitations, yet the parameter regime in which pairing survives strong correlations and competing instabilities has remained unresolved. Here we determine this regime for microwave-s...
Radiative capture in a non-relativistic system can become non-perturbative even when the underlying transition interaction is weak. We demonstrate this mechanism in a simple quantum-mechanical two-channel model with a systematic power counting, where strong mixing between scattering and bound states develops in a narro...
Bound states and resonances induced by short-range impurities modeled by circular potential wells are analyzed in the vicinity of flat and dispersive bands in gapped and gapless pseudospin-1 systems. We find that the bound and resonant states derived from the flat band show unusual characteristics originating from the...
Thermoelectric effects in superconductors are generally suppressed by the approximate particle-hole symmetry of the quasiparticle spectrum, but can become pronounced near defects that host particle-hole asymmetric bound states. Here, we investigate how the local thermoelectric response is modified when multiple vortice...
How a polaron loses its quasiparticle coherence with increasing temperature is a long-standing open problem. Holstein addressed it in 1959 only in the extreme antiadiabatic, strong-coupling limit, while more recent numerically exact approaches are largely restricted to one dimension. Here we solve this problem on squar...
Jeet Shannigrahi, J. Bonča, Mona Berciu· 0 citations
We study higher moments of quantum fluctuations and microscopic correlation energy in the three-dimensional Gross--Pitaevskii regime. For a smooth, compactly supported, nonnegative radial interaction and an $N$-independent normalized initial condensate wave function in $H^6$, we propagate the third spectral moment of a...
