arXiv subjects

Nicolas Viaux

Publications and source records attributed to Nicolas Viaux.

4 recordsLinked to original sources

arXiv2026

An effective topology-transfer nuisance for Genie-based neutrino-argon semi-inclusive analyses: a methodological proposal with MicroBooNE-constrained diagnostic

Liquid-argon TPC oscillation analyses increasingly split samples into proton-tagged (Np) and proton-less (0p) topologies at the ~35 MeV tracking threshold, but the standard GENIE Reweight library has no dial that transfers events across this boundary. We propose a single empirical nuisance parameter, $f_{\rm mig}$, that fills this gap as a per-event reweight on nominal GENIE output, implementable without event regeneration. It is presented as a methodological diagnostic: an effective topology-transfer surrogate absorbing an unspecified combination of near-threshold proton mismodelling effects (proton-side FSI, nucleon-momentum distribution, RES $Q^2$ shape, MEC kinematic shape), not a measurement of any single microscopic mechanism. As a reference scale, the position-dependent mean-field energy loss absent from GENIE's cascade is estimated from the $^{40}$Ar density profile to be a few percent, consistent with proton-transparency differences reported between cascade and transport generators on MicroBooNE data. The primary constraint is a direct scan on the MicroBooNE simultaneous CC 0p/Np differential cross-section release with no sector-weight regularisation: $\hat{f}_{\rm mig} = 0.093 \pm 0.024$, $3.8σ$ (Wilks) / $3.2σ$ (empirical). A supporting NC $Δ$ radiative sideband fit gives $\hat{f}_{\rm mig} = 0.050^{+0.029}_{-0.022}$, conditional on sector-weight priors; the two datasets share flux/detector systematics and are corroborating rather than independent. Introducing $f_{\rm mig}$ also relieves a compensatory CCRES sector-weight suppression in migration-blind fits. The extracted parameter is best understood as a flux-integrated effective nuisance direction for the MicroBooNE BNB configuration, suitable as a candidate GENIE dial for future LArTPC analyses pending detector-level validation.

hep-ph↗

arXiv2026

Quantum Magic Reveals CP Phases Invisible to Entanglement in Spin-0 Decays

All standard scalar quantum-information measures -- concurrence, negativity, entanglement entropy, the optimized CHSH bound, and quantum Fisher information -- are CP-blind in ideal \\ spin-0 $\to f\bar f$ decays because the two-qubit spin state is maximally entangled for every CP angle. We show that stabilizer magic, fixed in the physical Pauli frame of spin analysis, escapes this blind spot: the stabilizer Rényi entropy admits an exact closed form, vanishing at CP-definite and Clifford phases and peaking at maximal non-Clifford mixing. Two experimentally accessible, magic-inspired CP witnesses follow; the linear amplitude is $14.3\times$ more efficient than its quartic counterpart and reaches discovery-level sensitivity at the HL-LHC for $H\toτ^+τ^-$.

quant-ph↗

arXiv2026

Non-Monotonic Rotation Imprint on Time-Integrated Neutrino Spectral Moments in a 15\,$M_\odot$ Core-Collapse Supernova Sequence

We study the early post-bounce neutrino signal of the published Garching $15\,M_\odot$ rotating core-collapse supernova (CCSN) sequence consisting of non-rotating (NR), slowly rotating (SR, $Ω_0=0.5$ rad\,s$^{-1}$), and fast-rotating (FR, $Ω_0=150$ rad\,s$^{-1}$, artificially boosted ${\sim}300{\times}$) three-dimensional models. We present a new analysis of these publicly available simulation data; no new simulations were performed. Our central result, for this specific model sequence, is that SR and FR shift the integrated spectral moments in \emph{opposite directions} relative to NR: FR drives the spectra toward softer, more-pinched states, while SR moves them weakly toward harder, less-pinched states. Placed in a spectral-shift plane $(Δ\langle E\rangle_L,\,Δα_L)$, NR sits at the origin, and SR and FR occupy \emph{diagonally opposite quadrants}, making the non-monotonic response immediately visible as an anti-correlation in two spectral dimensions simultaneously. The focus is the accretion interval $t_{\rm pb}=0.05$--$0.30$\,s, where the rotation imprint is strongest. Quantitatively, fast rotation produces $Δ\langle E_{ν_e}\rangle_L=-0.513$\,MeV and $Δα_{ν_e}=+0.161$, with corresponding shifts $Δ\langle E_{\barν_e}\rangle_L=-0.440$\,MeV and $Δα_{\barν_e}=+0.173$; the SR shifts are an order of magnitude smaller and in the opposite sense. The fast-rotation signature is coherent across all $15\,488$ lines of sight and is established during early accretion. With only three models from a single progenitor family, this result is a phenomenological characterization of one published sequence and a suggestive indication of a non-monotonic, possibly strongly nonlinear, rotational response within this sequence; the functional form and generality of the dependence on $Ω_0$ remain unconstrained.

astro-ph.HE↗

arXiv2015

Confronting recent AMS-02 positron fraction and Fermi-LAT Extragalactic Gamma-Ray Background measurements with gravitino dark matter

Recent positron flux fraction measurements in cosmic-rays (CR) made by the AMS-02 satellite confirm and extends the evidence on the existence of a new (yet unknown) source of high energy positrons. To explain this excess, we use the gravitino of bilinear R-parity violating SUSY models as a decaying Dark Matter candidate, as the source of those high energy particles. Being a long lived weak-interacting and spin 3/2 particle, it offers several particularities which makes it an attractive candidate. We compute the electron, positron and $γ$-ray\ fluxes produced by each gravitino decay channel at the Earth. Combining the flux from the different decay modes we can fit AMS-02 measurements of the positron fraction, as well as the electron and positron fluxes, with a gravitino mass in the range $1-2$ TeV and lifetimes of $\sim 1.0-0.8\times 10^{26}$ s. . Then, we study the viability of these scenarios through their implications in $γ$-ray observations. We set limits on the gravitino lifetime using the Extragalactic $γ$-ray Background recently reported by the {\it Fermi}-LAT Collaboration and a state-of-the-art model of its known contributors. These limits exclude the gravitino parameter space which provides an acceptable explanation of the AMS-02 data. Therefore, we conclude that the gravitino of bilinear R-parity violating models is ruled out as the unique primary source of electrons and positrons needed to explain the rise in the positron fraction.

hep-ph↗