arXiv subjects

Sanskriti Agrawal

Publications and source records attributed to Sanskriti Agrawal.

5 recordsLinked to original sources

arXiv2026

Exact Amplitude Reconstruction in the Real Common-Phase Sector of Small-x Diffractive Energy Flow

We develop an operator-level framework for reconstructing the angular structure of small-$x$ diffractive amplitudes from energy-flow measurements. Focusing on coherent diffractive dijet production in the leading-eikonal approximation, we establish the relation between the angular multipoles of the dipole amplitude, the gluon Wigner distribution, and the diffractive scattering amplitude, while keeping their distinct radial transforms explicit. We show that, in the real common-phase sector and away from diffractive zeros, the normalized scattering amplitude can be reconstructed directly, up to a global sign convention, from the square root of the normalized energy-flow distribution. For generic complex amplitudes, the measured intensity instead determines autocorrelations of the amplitude spectrum and phase retrieval is not unique without additional information. We further discuss corrections arising from harmonic-dependent phases, practical conditions for an EIC extraction, and effects beyond the leading-eikonal approximation.

hep-ph↗

arXiv2026

Soft-Radiation-Induced Decoherence of Heavy-Quark Spin Entanglement at the Electron-Ion Collider

Using the soft-gluon theorem, we identify a soft-recoil mechanism by which unresolved gluon radiation induces decoherence in the spin correlations of heavy quark-antiquark pairs produced in deep-inelastic scattering. We show the eikonal soft contribution preserves the Born spin structure, whereas the subleading soft term generates stochastic recoil-induced rotations of the spin-correlation plane. Upon tracing over the unresolved gluon, these rotations produce an effective dephasing channel: the normal-axis correlation remains unchanged at this order, while the in-plane spin coherences are suppressed. We estimate the resulting reduction of concurrence and Bell-CHSH violation, and propose a radiation-binned EIC observable based on the ratio of in-plane to normal spin correlations. This observable isolates the characteristic anisotropic suppression predicted by the soft-recoil mechanism and provides a measurable handle on radiation-induced spin decoherence of an entangled quark-antiquark pair produced in a deep-inelastic scattering process.

hep-ph↗

arXiv2025

Entanglement Negativity of Spin-Orbit Correlations in a general Qubit-Qudit Setup

We present the complete eigenvalue spectrum of the partially transposed density matrix for a pure bipartite quantum state acting on a generic $2 \otimes n$ Hilbert space. The spectrum contains four non-zero eigenvalues, as, \begin{eqnarray} λ_{1,2}=\pm \sqrt{A}, ~~~ λ_{3,4}= \frac{1}{2}(1\pm\sqrt{1-4 A}), \nonumber \end{eqnarray} where $A$ is the determinant of the reduced density matrix (traced over the larger subspace). As $0 \leqslant A \leqslant1/4$, only one is negative among the four non-trivial eigenvalues. Within this qubit-qudit framework, we further studied the negativity as a measure of entanglement for the case of spin-orbit correlation of partons inside a proton. The entanglement negativity for spin-orbit correlations is found to be related to the gluon helicity PDF and the Hermitian angle of the associated Hilbert space for linearly polarized protons.

hep-ph↗

arXiv2024

Small-$x$ evolution of dipole amplitude in momentum space: forward--off-forward correspondence

We have shown that the small-$x$ evolution of the off-forward leading-log dipole scattering amplitudes, both pomeron and odderon, in the momentum space can be completely determined by the evolution of the respective forward amplitudes, with rescaled momenta. In position space, if there is translation symmetry (assumption of a large nucleus), the dipole cross section depends on the positions of quarks and anti-quarks only through their separation. The present study is an equivalent proposition in the momentum space -- where translation symmetry in momentum bifurcates the amplitudes into two translationally symmetric functions along the ${\bf k}$ line in the ${\bf k}-{\bf Δ}$ plane. It also shows that high energy evolutions of dipole GTMDs can be achieved only by studying the evolution of dipole TMDs at small-$x$.

hep-ph↗

arXiv2024

Spin-flip gluon GTMD $F_{1,2}$ at small-$x$

Until recently the spin-flip processes in the deep inelastic scatterings are thought to be suppressed in the high energy. We found a positive intercept for the spin-flip generalized transverse momentum-dependent parton distribution (GTMDs) ${\rm Re}(F_{1,2})$ as, \begin{eqnarray} {\rm Re}(F_{1,2}) \sim \left(\frac{1}{x}\right)^{{\bar α}_s\left(4\ln2-8/3\right)} \left(\cos 3ϕ_{kΔ} +\cos ϕ_{kΔ}\right). \nonumber \end{eqnarray} This is done by analytically solving the integro-differential evolution equation for ${\rm Re}(F_{1,2})$, recently proposed by Hatta and Zhou, in the dilute regime. Interestingly, the surviving solution corresponds to conformal spin $n=2$ and carries an explicit $\cos 3ϕ_{kΔ} + \cos ϕ_{kΔ}$ azimuthal dependence. As the imaginary part of $F_{1,2}$, is related to the spin-dependent odderon or gluon Siver function and scales as ${\rm Im}(F_{1,2}) \sim x^{0}$, the positive intercept for ${\rm Re}(F_{1,2})$, implies that it is expected to dominate over the gluon Siver function in the small-$x$ limit - and may directly impact the modeling of unpolarised GTMDs and associated spin-flip processes.

hep-ph↗