CERN Accelerating science

Article
Report number	FERMILAB-CONF-23-770-T
Title	The impact of nuclear effect modeling on the cross-section ratio $\nu_e/\nu_\mu$ and its impact for futrue measurements of CP violation
Author(s)	Dieminger, T (Zurich, ETH) ; Dolan, S (CERN) ; Sgalaberna, D (Zurich, ETH) ; Nikolakopoulos, A (Fermilab) ; Dealtry, T (Lancaster U.) ; Bolognesi, S (IRFU, Saclay) ; Pickering, L (Royal Holloway, U. of London) ; Rubbia, A (Zurich, ETH)
Publication	2023
Number of pages	6
In:	PoS EPS-HEP2023 (2024) 183
In:	2023 European Physical Society Conference on High Energy Physics (EPS-HEP2023), Hamburg, Germany, 20 - 25 Aug 2023, pp.183
DOI	10.22323/1.449.0183
Subject category	Nuclear Physics - Theory ; Particle Physics - Phenomenology
Abstract	Long-baseline (LBL) neutrino oscillation experiments search for Charge-Parity (CP) violation in the leptonic sector by precisely measuring the $\nu_\mu\to\nu_e$ and $\overline{\nu}_\mu\to\overline{\nu}_e$ appearance probabilities.One of the dominant systematic uncertainties on the measurements of CP violation, comes from our modeling of the $\nu_e/\overline{\nu}_e$ cross-section ratio, which is subject to a range of uncertainties related to poorly-constrained nuclear physics processes.Whilst tight constraints on the $\nu_\mu/\overline{\nu}_\mu$ cross-section can be achieved using LBL experiment's near detector data, the lepton mass differences mean that the extrapolation to the $\nu_e/\overline{\nu}_e$ is not trivial.Currently running LBL experiments reach a sensitivity to exclude the CP conserving hypothesis of about three standard deviations for a relatively large range of $\delta_{CP}$ values, hence a more accurate evaluation of the $\nu_e/\overline{\nu}_e$ related uncertainties becomes increasingly crucial.Following up on work by Nikolakopoulos et al. \cite{Nik}, we present the analysis from \cite{UncertaintiesOTDi}, quantifying the potential for miss-modelling of the $\nu_\mu/\nu_e, \ \overline{\nu}_\mu / \overline{\nu}_e$ and $\nu_e/\overline{\nu}_e$ cross sections due to nuclear effects as a model spread in the full kinematic phase space for CCQE interactions.This impact is then propagated to simulated experimental configurations based on the Hyper-K and ESS$\nu$SB experiments.Significant differences between the theoretical models are found, which largely lie in regions of phase space that contribute only a small portion of the flux integrated cross sections.Overall, a systematic uncertainty on the oscillated flux-averaged $\nu_e/\overline{\nu}_e$ cross section of $\sim 2$\% and $\sim4$\% is found for the simulated Hyper-K and ESS$\nu$SB experiments respectively.
Copyright/License	CC-BY-NC-ND-4.0

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