arXiv subjects

Bahruz Suleymanli

Publications and source records attributed to Bahruz Suleymanli.

7 recordsLinked to original sources

arXiv2026

Quadratic pair-breaking absorption edge from Anderson localization in a superconducting wire

We show that Anderson localization fundamentally reshapes dissipative superconducting electrodynamics, replacing the linear Mattis--Bardeen pair-breaking onset with a parametrically weaker quadratic Mott edge while leaving the quasiparticle spectrum unchanged. We derive this behavior for a weakly disordered single-channel wire with a spatially uniform $s$-wave pair potential using a Nambu-space extension of the Berezinskii diagram technique that resums elastic impurity scattering to all orders. Conservation of the Bogoliubov branch collapses the Nambu diagram hierarchy onto an exactly solvable localization problem. The localization length remains equal to its normal-state value, whereas the localization time diverges at the gap edge. The new absorption edge results from the product of the superconducting pair-creation coherence factor and the Mott-suppressed current matrix elements between localized orbitals, which generates the characteristic double logarithm. Localization also reduces the Hebel--Slichter coherence peak. The resulting theory provides an all-orders benchmark for microwave and spin-relaxation experiments on localized superconducting nanowires.

cond-mat.supr-con↗

arXiv2026

The Effects of Multi-$Λ$ Hyperons on Collective Modes in Nuclei

The dynamical influence of $Λ$ hyperons on the excited-state properties of closed-shell multi-$Λ$ Ca, Ni, Sn and Pb hypernuclei is investigated using the self-consistent Hartree-Fock + Random Phase Approximation in coordinate space. The strength distributions for the isoscalar monopole, isovector dipole, and isoscalar quadrupole modes are calculated, revealing a systematic upward energy shift with increasing $Λ$ hyperon number $-S$. The scaling behavior of the computed centroid energies $\sqrt{m_1/m_{-1}}$ with respect to both the mass and hyperon number is determined. The nuclear incompressibility modulus $K_A$ is found to increase monotonically with $-S$. The largest value is found in the $^{258}_{50Λ}$Pb hypernucleus, reaching $K_A = 322 $ MeV. Calculations in uniform hypernuclear matter confirm that this stiffening is a bulk effect driven by both the $NΛ$ and $ΛΛ$ interactions. Analysis of the transition densities for states with maximal collective coherence indicates that the dynamical effect of $Λ$ hyperons is predominantly in phase with the protons, especially in the case of the isovector E1 modes.

nucl-th↗

arXiv2026

Impact of spin-orbit coupling on electron correlation corrections to the density of states in anisotropic conductors

We study Altshuler-Aronov-type interaction corrections to the single-particle density of states (DOS) in a strongly anisotropic 2D conductor with an open Fermi surface (FS) and weak disorder, in the presence of coexisting Rashba and Dresselhaus spin-orbit couplings (SOCs) constrained to the longitudinal direction. The low-energy band consists of two warped sheets weakly tunnel-coupled transversely; SOC splits the sheets into helicity branches with a fixed spin axis. Working in a Matsubara space, we compute the exchange contribution in the diffusion channel with dynamically screened Coulomb interaction and an impurity ladder. The resulting DOS anomaly exhibits a dimensional crossover governed by the transverse coupling scale $\varepsilon_c$. Close to the Fermi level ($|\varepsilon-\varepsilon_F|<\varepsilon_c$), the system behaves two-dimensionally, featuring a logarithmic DOS dip whose magnitude is enhanced by intrinsic SOCs. Further from the Fermi level ($|\varepsilon-\varepsilon_F|\!>\!\varepsilon_c$), the system behaves quasi-one-dimensionally, featuring a sharper square-root singularity whose amplitude is remarkably enhanced by the SOCs. Notably, we identify a critical SOC strength at which these spin-orbit effects exactly cancel the electron-correlation correction, perfectly restoring the unperturbed density of states. Furthermore, increasing the SOC beyond this critical point inverts the sign of the anomaly entirely, yielding a positive DOS correction. This sign reversal fundamentally alters the energy dependence, such that at energies beyond $\varepsilon_F + \varepsilon_c$, the positive correction decays to smaller values as energy increases, opposite to the standard negative correction. This contrasting trend provides a distinct spectroscopic signature of SOC-modulated correlation effects.

cond-mat.mes-hall↗

arXiv2026

Quasiparticle properties of a single $Λ$ impurity in symmetric nuclear matter with a regulated $NΛ$ interaction

We explore the quasiparticle properties of a single $Λ$ hyperon propagating through symmetric nuclear matter using the Green's function formalism. The $NΛ$ interaction is described by a non-local regulated low-momentum contact potential with a leading-order constant term and a next-to-leading-order derivative correction. The two coupling constants in the ${}^1S_0$ and ${}^3S_1$ channels are fixed by matching the vacuum on-shell $T$ matrix to the scattering length and effective range obtained from modern next-to-next-to-leading-order chiral effective field theory. Using this effective interaction, we calculate the retarded $Λ$ self-energy from the in-medium $NΛ$ ladder $T$ matrix, which sums repeated $NΛ$ scattering in the nucleonic medium. At saturation density, the zero-momentum quasiparticle pole is found at $E_{\rm qp}(0,ρ_{\rm sat})=-29.55~{\rm MeV}$, in good agreement with the empirical depth of the single $Λ$ potential in nuclear matter. The self-energy decomposition gives a static Born contribution $Σ_Λ^{\rm Born}(0)=-26.36~{\rm MeV}$ and a dynamical correlation contribution ${\rm Re}\,Σ_Λ^{\rm corr,R}(0,E_{\rm qp})=-3.19~{\rm MeV}$, showing that repeated in-medium $NΛ$ scattering is needed to reproduce the empirical binding scale. The quasiparticle remains narrow and well defined, with a large residue $Z(0)=0.98$, a small damping width $Γ(0)=0.023~{\rm MeV}$, and a sharp spectral peak near the quasiparticle energy. At finite momentum, the $Λ$ quasiparticle becomes less bound, with $E_{\rm qp}(k,ρ_{\rm sat})$ increasing from $-29.55~{\rm MeV}$ at $k=0$ to $-6.49~{\rm MeV}$ at $k=1~{\rm fm}^{-1}$, while the residue and width change only weakly. A low-momentum fit gives $m_Λ^*/m_Λ=0.747$, consistent with the range obtained in Brueckner calculations with Nijmegen hyperon--nucleon potentials.

nucl-th↗

arXiv2026

Green's Function Formalism for Impurity-Induced Resonances in Sub-barrier Proton-Nucleus Scattering

Motivated by recent experimental refinements of stellar reaction rates, we establish a non-perturbative Green's function formalism based on the exact solution of the Dyson equation for sub-barrier proton-nucleus resonant scattering. By utilizing bare Green's functions to map the quantum tunneling problem onto a scattering formalism, we demonstrate that the summation of infinite quantum paths recovers the exact tunneling coefficients, enabling an analytical solution of the Dyson equation where the strong nuclear force is modeled as a surface delta-shell impurity embedded within the Coulomb field. Applying this framework to the astrophysically relevant $p + {}^{7}\text{Li}$, $p + {}^{14}\text{N}$, and $p + {}^{23}\text{Na}$ systems, we achieve precise agreement with experimental resonance energies while revealing a fundamental physical distinction in resonance formation. The heavier ${}^{23}\text{Na}$ system is identified as a saturated state, residing on a geometric plateau where the resonance energy becomes insensitive to the interaction strength; our calculated value of $2.11$~MeV aligns remarkably well with the experimental level of $2.08$~MeV. In contrast, the lighter ${}^7\text{Li}$ and ${}^{14}\text{N}$ systems emerge as threshold states in a weak-coupling window, where the resonance energy is highly sensitive to the potential parameters and is sustained near the continuum edge. In this regime, our model yields energies of $0.489$~MeV and $1.067$~MeV, closely reproducing the experimental benchmarks of $0.441$~MeV and $1.058$~MeV, respectively. We demonstrate that these threshold states are characterized by a significant enhancement of the resonant cross-section, driven by the inverse relationship between the tunneling width and the spectral density peak.

nucl-th↗

arXiv2025

Gap Anisotropy in Layered Superconductors Due to Rashba and Dresselhaus Spin-Orbit Interactions

The theory of layered superconductors is extended in the presence of Rashba and Dresselhaus spin-orbit interactions (SOIs). Using the intralayer BCS-like pairing interaction and employing the Gor'kov formalism, we obtain analytical expressions for the temperature Green's functions and determine the gap function $Δ$ which becomes complex in the presence of SOIs. In the absence of SOIs, $Δ$ is isotropic at both zero and finite temperatures, but it becomes anisotropic even in the presence of a single SOI. This anisotropy is related to the extra $\cos{k_z}$ factors in which the $k_z$ momentum along the $z$ direction contributes to the magnitude of the gap function. It is also found that SOIs suppress $Δ$ at both zero and finite temperatures, and for certain critical values of SOIs and beyond $Δ$ vanishes. Analytical expressions for the critical values of SOIs at zero temperature are obtained. Additionally, how the BCS equation for layered superconductors changes in the presence of SOIs is determined.

cond-mat.supr-con↗

arXiv2024

Effects of Finite Temperature and Pairing Correlations in Multi-$Λ$ Hypernuclei

The influence of finite temperatures and pairing correlations on the ground state properties of multi $Λ$- Ca, Sn and Pb hypernuclei is explored using finite temperature Hartree Fock Bogoliubov approach and contact pairing interaction. A critical temperature is predicted and is in agreement with the Bardeen Cooper Schrieffer relationship $k_B T_C^Λ\approx 0.5 Δ^{T=0}_Λ$, beyond which pairing correlations drop to zero. Particle densities, $Λ$ single particle energies, and nuclear radii are weakly impacted by pairing as well as by finite temperatures. However, other nuclear properties which are more sensitive to pairing correlations, such as $Λ$ pairing gaps, condensation energies, and abnormal densities are also more impacted by finite temperature, especially around the critical temperature. Furthermore, calculations show the occurrence of the pairing re-entrance effect in the $^{280}_{70Λ}$Pb hyperon drip line hypernucleus. Our study provides insight into the thermal evolution of $Λ$ pairing, i.e. the emergence and vanishing of pairing correlations in multi $Λ$ hypernuclei as a function of temperature.

nucl-th↗