arXiv subjects

Tia Pandit

Publications and source records attributed to Tia Pandit.

3 recordsLinked to original sources

arXiv2026

Matter-Induced CPT Violation and Earth-Density Stratification Effects in Long-Baseline Neutrino Oscillation Experiments

We present a unified analysis of two matter-potential systematics in long-baseline (LBL) neutrino oscillation experiments. Matter-induced extrinsic CPT violation produces a non-zero asymmetry $A_{μe}^{CPT} = (P_{μe} - P_{\barμ\bar{e}})/(P_{μe} + P_{\barμ\bar{e}})$, computed here with exact three-flavour matrix-exponentiation propagators for T2K, NO$ν$A, DUNE, and Hyper-Kamiokande; values range from 0.022 to 0.180 at the respective peak energies and differ by up to 9\% between normal and inverted mass orderings. The three-dimensional surface $A_{μe}^{CPT}(E, δ_{CP})$ at the DUNE baseline reveals an entanglement between extrinsic CPT violation and intrinsic CP violation in the high-$L/E$ regime that requires joint statistical treatment. Concurrently, replacing the Preliminary Reference Earth Model (PREM) with a constant path-averaged density introduces a $δ_{CP}$-reconstruction bias below $0.3^{\circ}$ for $L \leq 5000$ km but growing to $17.8^{\circ}$ at $L = 7000$ km and $172.2^{\circ}$ at $L = 12000$ km. Since both effects share the same matter-potential Hamiltonian they must be modelled jointly; a Poisson log-likelihood $χ^2$ statistic with nuisance-parameter pull terms is used to quantify the bias.

hep-ph↗

arXiv2026

Correlated Matter Induced Biases in Long-Baseline Neutrino Oscillation Measurements

We demonstrate that treating Earth matter effects via a constant-density approximation introduces a fundamental systematic error in long-baseline neutrino oscillation analyses. Using exact numerical propagation through realistic PREM profiles, we show that matter-profile mismodeling does not merely affect the $ν_μ\rightarrowν_{e}$ appearance probability, but generates correlated biases across the $ν_μ\rightarrowν_τ$ and $ν_μ\rightarrowν_μ$ channels as dictated by PMNS unitarity. Our stochastic analysis reveals that the $ν_μ\rightarrowν_τ$ channel is the most volatile carrier of the geophysical systematic. Across varying correlation lengths at baselines like $5000$ km and $7000$ km, the $τ$-appearance channel consistently carries a larger mean bias and variance than the standard $ν_μ\rightarrowν_{e}$ appearance channel. These findings demonstrate that spatially resolved density treatments are a mathematical necessity for the analysis frameworks of future precision neutrino facilities.

hep-ph↗

arXiv2026

Earth-Density Effects in Long Baseline Neutrino Experiments

Earth matter density uncertainties play a non trivial role in three flavor neutrino oscillations in matter, particularly for the muon to electron appearance channel that underpins CP violation measurements in long baseline experiments. We demonstrate that when realistic spatial variations of the Earths density are taken into account, the oscillation probabilities acquire additional, energy dependent structures that cannot be captured by path-averaged density approximations. We show that mismodeling of the matter density profile can introduce degeneracies that obscure genuine leptonic CP violating effects, thereby degrading parameter sensitivity and biasing the inference of the CP phase. Identifying energy regions in which CP sensitivity remains robust against matter density uncertainties is therefore essential. These considerations indicate that marginalization over a single effective density parameter is insufficient for next generation precision measurements and motivate the incorporation of spatially resolved Earth density profiles in the analysis frameworks of future long-baseline neutrino oscillation experiments.

hep-ph↗