arXiv subjects

Carlos A. Argüelles

Publications and source records attributed to Carlos A. Argüelles.

At least 19 recordsLinked to original sources

arXiv2026

Sensitivity of the IceCube atmospheric muon rate to decadal trends in the effective atmospheric temperature

Decadal changes in the Antarctic stratosphere, generally associated with ozone recovery and shifts in polar circulation, are of broad geophysical interest. However, independent long-term measurements of the atmosphere above the Antarctic interior are scarce. We assess whether the atmospheric muon rate recorded by IceCube could constrain decadal changes in the effective atmospheric temperature, $T_\mathrm{eff}$, a weighted average of temperature through the atmosphere that is most sensitive to the stratosphere. Using public atmospheric reanalysis data and records of cosmic-ray, solar, and geomagnetic variability, we reproduce the measured seasonal response of the IceCube muon rate. We then test whether the same response applies to long-term temperature changes with a different vertical temperature profile. The limiting requirement is detector stability rather than counting statistics: an unmodeled muon rate drift of $1\%\,\mathrm{decade^{-1}}$ would mimic a temperature trend of $2.8\,\mathrm{K\,decade^{-1}}$. The long-term rate must therefore be stable to approximately $0.3\%\,\mathrm{decade^{-1}}$. Within this budget, snow accumulation contributions can be constrained. For a 14-year record, atmospheric variability gives a one-sided 95% CL statistical sensitivity of $1.6\,\mathrm{K\,decade^{-1}}$. Given this sensitivity, the $\sim0.9\,\mathrm{K\,decade^{-1}}$ cooling indicated by the 2011-2025 atmospheric records would become distinguishable after approximately 30 years of measurement.

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arXiv2026

CURTAIN: Towards a Foundation Model for Neutrino Telescopes

Neutrino telescopes record more than a trillion photon detections per year, yet there does not exist a self-supervised learning (SSL) task which fully satisfies all three conditions: improving as the pretraining set grows, transferring to a different detector, and outperforming the best model trained without pretraining at all. We introduce CURTAIN, a temporal masking scheme and the first SSL task for neutrino telescopes that achieves all of these goals. Downstream performance monotonically improves with the number of pretraining events, as predicted by scaling laws. Our encoder builds on DeepIce, currently the leading model on the NuBench benchmarks direction reconstruction task. Pretraining it with CURTAIN reduces its median angular error by 45% and its median energy error by 31% compared to training from scratch. It also transfers to a detector geometry never seen in pretraining, reducing the median angular error by 36% compared to training from scratch. At matched capacity and pretraining data, CURTAIN-pretrained encoders beat those pretrained by existing SSL tasks on both tasks and at every pretraining set size.

hep-ex↗

arXiv2026

Evidence for Normal Neutrino Ordering with Combined Atmospheric Neutrino Experiments

We present a combined analysis of the latest publicly available atmospheric neutrino data from Super-Kamiokande including all data-taking stages previous to the gadolinium phase, IceCube-DeepCore, and the six-detection-unit configuration of KM3NeT/ORCA. Our fit uses all event samples simultaneously and treats the systematic uncertainties shared among experiments as fully correlated, while detector-response uncertainties are modeled independently for each experiment. The combined data constrain the atmospheric oscillation parameters to $Δm^2_{31} = 2.44^{+0.06}_{-0.04} \times 10^{-3}\,\mathrm{eV}^2$ and $\sin^2θ_{23} = 0.52^{+0.03}_{-0.04}$, with a precision of $2.2\%$ and $6.1\%$, respectively, which is competitive with current accelerator-based measurements, and independently constrain the $CP$-violating phase to $δ_{CP} = 1.30^{+0.24}_{-0.28}~π$. Finally, comparing the orderings of the neutrino mass spectrum, we find a preference for the normal ordering with $Δχ^2 = 11.0$; further calibrated with pseudoexperiments, we exclude the inverted ordering at $99.95\%$ confidence level ($3.3σ$). In a joint fit including 207 days of JUNO data, we further exclude the inverted ordering at $Δχ^2 = 15.1$, corresponding to $3.9 σ$.

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arXiv2026

Neutrino Telescope Event Classification on Quantum Computers

Quantum computers represent a new computational paradigm with steadily improving hardware capabilities. In this article, we present the first study exploring how current quantum computers can be used to classify different neutrino event types observed in neutrino telescopes. We investigate two quantum machine learning approaches, Neural Projected Quantum Kernels (NPQKs) and Quantum Convolutional Neural Networks (QCNNs), and find that both achieve classification performance comparable to classical machine learning methods across a wide energy range. By introducing a moment-of-inertia-based encoding scheme and a novel preprocessing approach, we enable efficient and scalable learning with large neutrino astronomy datasets. Tested on both simulators and the IBM Strasbourg quantum processor, the NPQK achieves a testing accuracy near 80%, with robust results above 1 TeV and close agreement between simulation and hardware performance. A simulated QCNN achieves a ~70% accuracy over the same energy range. These results underscore the promise of quantum machine learning for neutrino astronomy, paving the way for future advances as quantum hardware matures.

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arXiv2026

The road to $H_0$, $Ω_m$, and $w$ with a global neutrino-telescope network

The newly measured correlation between the neutrino and X-ray luminosities of Seyfert galaxies has yielded the first neutrino-based measurement of the Hubble constant. Building on this result, we forecast the reach of a global neutrino-telescope network by 2030, utilizing full-sky IceCube exposures combined with KM3NeT-ARCA and Baikal-GVD. We find that this 2030 configuration sharpens the neutrino-measured Hubble constant from today's $H_0 = 66^{+44}_{-37}$ to $H_0 =66^{+15}_{-13}$ km s$^{-1}$ Mpc$^{-1}$. Additionally, we project that the disk-corona slope of the neutrino X-ray luminosity relation ($L_ν\propto L_X^β$) will reach $β=0.72\pm0.04$, enabling a $\geq \!5σ$ exclusion of the calorimetric value $β=1$. Finally, we show that, if a high-redshift population of neutrino sources, such as JWST's "little red dots," is identified and obeys the same luminosity relation, we can obtain a new independent measurement of the matter density $Ω_m$ and the dark energy equation-of-state parameter $w$.

astro-ph.CO↗

arXiv2026

Seafloor Topography Enhances KM3NeT Sensitivity to ANITA-like Events

In this article, we introduce the concept of topographic enhancement in the context of ultra-high-energy neutrino detection by underwater neutrino telescopes. We demonstrate that the local topography around KM3NeT/ARCA can increase the detection efficiency in scenarios involving long-lived particles by up to a factor of $\sim 3$ due to the presence of an underwater mountain range in the direction of Malta. We consider a simplified model-independent approach that parametrizes the new physics able to generate both track-like and cascade-like signals in neutrino telescopes. When explaining the KM3-230213A event with a diffuse dark flux hypothesis, including its azimuthal direction--in addition to the zenith angle--provides additional constraints on the parameter space. In this effective model, the observations by KM3NeT and ANITA-IV can be simultaneously explained, but a global tension with the lack of a corresponding detection in IceCube remains at 2.7 sigma. This work underscores the importance of incorporating topographic effects in the design and optimization of next-generation neutrino telescopes, as is done in the context of mountain-based detectors such as TAMBO. We present a numerical code which can be used to easily extend this topographical analysis to other experiments.

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arXiv2026

A Differentiable Neural Surrogate for Photon Propagation in Neutrino Telescopes

Large-volume neutrino telescopes infer neutrino properties from Cherenkov light, but simulating the transport of billions of photons through highly scattering ice or water is computationally costly. We introduce candela, a differentiable SIREN neural field that learns the photon Green's function of the IceCube Neutrino Observatory, a cubic-kilometer detector embedded in Antarctic glacial ice. Given a point-like energy deposit and sensor, it predicts the expected photon yield and full arrival-time distribution at the sensor. Complete events are simulated by decomposing charged-particle energy deposits into point-like sources and superposing their predicted sensor responses. Trained on Monte-Carlo simulations, candela generates events $50$--$100\times$ faster than existing methods, with cost scaling only weakly with neutrino energy. It keeps median yields within $2\%$ of the MC expectation and timing distributions at the MC statistical floor across six photon-count decades. The model also provides end-to-end gradients with respect to event parameters and opens a path toward optimizing scattering-medium properties, which often dominate systematic uncertainties in neutrino telescopes.

astro-ph.HE↗

arXiv2026

Three-Technology Ultra-High-Energy Neutrino Flavor Measurement

Ultra-high-energy (UHE) neutrinos, with energies above $100\,\mathrm{PeV}$, are powerful probes of fundamental physics, offering unique opportunities to test and constrain models beyond the Standard Model. A central challenge is achieving sensitivity to their flavor composition, which encodes information about production mechanisms at the source as well as potential new physics during propagation. We propose, for the first time, a three-technology strategy to measure the flavor composition of UHE neutrinos by leveraging the complementary strengths of planned and existing experiments. This approach integrates in-ice radio (ARA, ARIANNA, RNO-G, the IceCube-Gen2 radio array), Earth-skimming (TAMBO, POEMMA, Trinity, AUGER, GRAND200k), and in-ice optical Cherenkov detectors (the IceCube-Gen2 optical array). We demonstrate the potential to achieve unprecedented sensitivity to UHE neutrino flavors. The method can be used to probe an energy-dependent neutrino flavor transition at the source across energies ranging from TeV to EeV. As such, this article highlights the discovery potential of a coordinated, multi-technology program for advancing both high-energy and ultra-high-energy neutrino astrophysics.

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arXiv2026

Probing Scalar Non-Standard Neutrino Interactions using High-Energy Astrophysical Neutrinos

Scalar non-standard interaction (SNSI) of neutrinos contributes as modifications to the neutrino mass matrix in the oscillation Hamiltonian and can induce a small active-sterile mass splitting due to the matter effect induced by the relic neutrino background via a Majorana-type interaction. This framework leads to pseudo-Dirac behavior of neutrinos, introducing rich phenomenology in neutrino oscillations, particularly for high-energy astrophysical neutrinos. We show that these hyperfine active-sterile splittings imprint themselves in two complementary ways on high-energy astrophysical neutrino flux, namely, in modifying the flavor composition and energy distribution. In this work, we perform both flavor and spectral analyses of the high-energy astrophysical neutrino flux to probe SNSI. We confront the predicted flavor ratios with current IceCube measurements and with the projected reach of next-generation detectors such as IceCube-Gen2. For the spectral analysis, we use the diffuse-flux ESTES (tracks) and cascade data sets, together with point-source spectral shape analysis based on a recent catalog of neutrino-bright sources. The regions excluded by the combined flavor and spectral analyses are translated into limits on the underlying SNSI parameters, namely, Yukawa couplings and scalar mass, providing new sensitivities on the SNSI parameter space for ultra-light mediators.

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arXiv2026

Measurement of the Hubble constant with high-energy neutrinos

Measuring distances in the Universe is one of the hardest problems in physics and astronomy. Almost every distance probe relies on photons, whose propagation across cosmic distances introduces extinction, absorption, scattering, and radiative-transfer effects. Neutrinos suffer none of these and propagate unattenuated through dust, intergalactic medium, and dense source environments alike. We introduce a new distance-ladder method for measuring the Hubble constant $H_0$ using high-energy astrophysical neutrinos from point sources as standardizable candles, and report its first observational realization. Using 12 X-ray-selected Seyfert galaxies for which IceCube reports significant per-source neutrino excesses in its 14-year public point-source release, we exploit the disk-corona correlation $L_ν= κ\, L_X^β$ between neutrino and X-ray luminosities to construct a neutrino distance ladder anchored by non-redshift distances to NGC 1068 (Cepheid + TRGB). We find $H_0 = 49^{+40}_{-30}\,\mathrm{km\,s^{-1}\,Mpc^{-1}}$ and $β= 0.67^{+0.16}_{-0.25}$ (68% credible intervals), with the corona slope disfavoring the calorimetric limit $β= 1$ at ${\sim}2σ$. The result is consistent with existing $H_0$ determinations from Planck and SH0ES within 1$σ$. While the uncertainty on $H_0$ is large, the measurement is free of electromagnetic propagation systematics and demonstrates the viability of neutrinos as a novel cosmographical probe.

astro-ph.CO↗

arXiv2026

Astrophysical Neutrino Sources as Colliders

High-energy neutrinos arise from processes at large center-of-mass energies, offering a window to test physics at comparable scales or beyond those accessible in collider experiments on Earth. Here, we present a recipe for extracting two-sided bounds on the inelastic $pp$ and $pγ$ cross sections from neutrino point-source data, by independently constraining every astrophysical input (cosmic-ray luminosities and target densities) through electromagnetic observations or theoretical arguments. The cross section is then the only remaining free parameter. Applying this framework to the IceCube associations with TXS~0506+056, NGC~1068, and the Galactic Plane, to a stacked population of eleven X-ray bright Seyfert galaxies, to the ultra-high-energy KM3NeT event KM3-230213A, and to projected observations of ultra-high-energy neutrinos, we obtain constraints that span center-of-mass energies from $\sqrt{s}\sim 1$ GeV to $\sim 10^{5}$ GeV, some of which are well beyond the reach of the LHC and, for the $pγ$ channel, beyond HERA. Several of these bounds are more stringent than unitarity limits.

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arXiv2026

Four, One, and None: Quantifying the Ultra-High-Energy Neutrino Anomaly Across ANITA-IV, KM3NeT, and IceCube

The four near-horizon neutrino-like events reported by ANITA-IV and the ultra-high-energy track-like event KM3-230213A observed by KM3NeT imply neutrino event rates that are in tension with the absence of corresponding events at IceCube. In this work, we perform a joint analysis of these events, taking into account the absence of any corresponding ones at IceCube. We construct semi-analytic, energy- and direction-dependent effective areas for the three detectors and account for the time-dependent ANITA-IV and KM3NeT exposures. For a diffuse all-sky power-law flux varying both the normalization and the spectral index, the measured event rates across the three detectors are not reproduced. The best-fit configuration, corresponding to a tension of $\sim7.5σ$, predicts approximately five IceCube events while strongly underpredicting the ANITA-IV and KM3NeT counts. In contrast to the diffuse scenario, the tension can be substantially alleviated if the events arise from short-duration transients that occur exactly along the observed directions during the ANITA-IV and KM3NeT detection windows. Such a realization, however, is highly fine-tuned. If rare transients are instead distributed randomly across the full sky over the $\sim15$-year IceCube observation period, additional sources inevitably contribute to the IceCube exposure. For benchmark populations with a probability of approximately $10^{-4}$ to produce four favorable transients at ANITA-IV, the best-fit configuration of sources, out of $10^5$ Monte Carlo realizations, remains in $5.9σ$ tension. We conclude that, within the Standard Model, directional and temporal variations alone can not reconcile the ANITA-IV and KM3NeT observations with the IceCube null result, under both a diffuse all-sky flux and a rare-transient source hypothesis.

astro-ph.HE↗

arXiv2026

Charged Lepton Flavor Violation at Neutrino Telescopes

Any observation of charged lepton flavor violation (CLFV) would be a clear signal of beyond-the-Standard-Model physics. Here, we propose a novel CLFV search using neutrino telescopes with their large cosmic-ray muon samples. Specifically, we use a recent IceCube cosmic-ray muon dataset and propose a new search for muon-to-tau conversion inside the IceCube detector. We illustrate our idea with CLFV interactions described by model-independent Effective Field Theory (EFT) operators and present the IceCube sensitivity on the relevant EFT scale. We also consider a specific realization of the EFT operator in terms of an axial-vector $Z'$ interaction and show sensitivities in the $Z'$ mass-coupling plane. We compare our sensitivities with those from low-energy CLFV searches, as well as from current and future collider experiments. We also show projections from next-generation neutrino telescopes, such as IceCube-Gen2 and HUNT, and demonstrate how neutrino telescopes can provide a powerful complementary probe of CLFV.

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arXiv2026

When CPT Violation Hides in Plain Sight: How CP Measurements Are Compromised and How to Fix Them

The extraction of the leptonic charge-parity (CP)-violating phase $δ_{\rm CP}$ from long-baseline neutrino oscillation experiments rests on the assumption of charge-parity-time (CPT) conservation. We show that CPT violation, parametrized as an asymmetry $δΔm^2_{31} \equiv Δ\bar{m}^2_{31} - Δm^2_{31}$ between neutrino and antineutrino mass splittings, induces an effective, energy-dependent phase shift $ϕ_{\rm eff}(E)$ that is functionally degenerate with $δ_{\rm CP}$ in the appearance asymmetry $\langleΔP\rangle$. This has a profound implication for long-baseline experiments, where the tension between T2K and NO$ν$A CPT-conserving best-fit $δ_{\rm CP}$ values can be significantly alleviated by a CPT-violating truth; and a CPT-conserving fit can miss the true CP phase entirely for $|δΔm^2_{31}|\gtrsim 0.3\times10^{-3}~\text{eV}^2$ for DUNE. We then demonstrate that atmospheric neutrino telescopes provide the natural tool to resolve this degeneracy: using existing data from IceCube-DeepCore (7.74 yr) and KM3NeT/ORCA-6 (433 kt-yr), we derive a world-leading constraint on CPT-violation at $| δΔm^2_{31}|\leq 0.57\times10^{-3}~\text{eV}^2$ at 90% CL. With the IceCube Upgrade and full ORCA detector, we can reach a $1σ$ constraint at $10^{-4}~\text{eV}^2$ within a decade, providing the independent CPT constraint needed to ensure that DUNE's $δ_{\rm CP}$ measurement is unambiguous.

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arXiv2026

Towards the Detection of Thermal Solar Neutrinos

We show that $\sim$keV thermal solar neutrinos, arising from electroweak processes in the solar plasma, are kinematically accessible to large-volume dark matter direct detection experiments via electron ionization signatures. Using S2-only data from the XENONnT experiment, we place an upper limit on the thermal solar neutrino flux of $η\lesssim 1.2 \times 10^8$ times the standard model predicted value, while paired searches from XENONnT, LZ and PandaX give slightly weaker limits. The future XLZD experiment could improve these limits by orders of magnitude. While still far from a detection, this result establishes low-threshold direct detection experiments as a viable probe of the lowest-energy neutrino sources in astrophysics, with important implications for stellar physics and beyond.

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arXiv2026

Visible inelasticity as a probe of tau flavor content of astrophysical neutrinos

Astrophysical neutrinos provide a unique probe of neutrino flavor changes over cosmological baselines. While the tau component of the neutrino flux is expected to arise almost entirely from mixing, current measurements rely primarily on rare double-cascade signatures. We investigate a complementary method to measure the tau fraction using the visible inelasticity of starting track events in neutrino telescopes. Muonic decays of tau leptons produce tracks with systematically larger visible inelasticity than those from muon neutrino interactions, potentially enabling statistical separation of the two flavors. Using realistic IceCube exposures and detector performance, we show that this observable already yields competitive sensitivity to the tau-to-muon flux ratio, $R_{τμ}$, achievable with existing data. This approach may further enable flavor measurements of individual sources and the selection of tau-enhanced source catalogs. Starting-track inelasticity thus provides a powerful and immediately accessible probe of astrophysical neutrino flavor and of potential physics beyond standard neutrino mixing.

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arXiv2026

Exploring New Propagation Scales With Galactic Neutrinos

The recent observation of high-energy Galactic neutrinos by IceCube allows for searches of new physics affecting neutrino propagation on scales of $O(10^9-10^{15})\,\mathrm{km/GeV}$ in distance over energy. We assess the sensitivity of upcoming measurements of Galactic neutrinos by IceCube and KM3NeT to such new phenomena. We focus on two scenarios: quasi-Dirac neutrinos and neutrino decays. In the quasi-Dirac scenario, we find that joint measurements by IceCube and KM3NeT are sensitive to the mass-squared differences $δm^2 \in \left(10^{-13.6}~\mathrm{eV^2}, 10^{-12.3}~\mathrm{eV^2}\right)$ at the $90\%$ confidence level. For neutrino decays, the same measurements are sensitive to mass over lifetime ratios $m / τ> 10^{-12.8}~\mathrm{eV^2}$ at the same significance. Our results demonstrate that measurements of Galactic neutrinos by a global network of neutrino telescopes can probe signatures of neutrino mass models.

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arXiv2026

Improving Neutrino Point Source Sensitivity with Source-Informed Event Selection

Neutrino telescopes employ multi-level reconstruction chains, where computationally expensive high-quality reconstructions are applied only to events that survive initial quality cuts based on fast, coarse directional estimates. Currently, event selection between reconstruction levels is source-agnostic, giving no priority to events from directions of known neutrino source candidates. We propose a simple modification to inter-level event selection: preferentially retain events whose early-level reconstruction places them within an angular tolerance of pre-specified candidate source directions from established multi-messenger catalogs, while continuing to subsample remaining events at the baseline rate. Using a realistic two-level detector model with energy-dependent angular resolution, we show that this source-informed selection can improve median point source sensitivity by factors of $\sim 2$--$3$ compared to uniform subsampling, with the improvement depending on the baseline selection efficiency, angular tolerance, and correlation between reconstruction qualities at different levels. For catalogs of $\mathcal{O}(100)$ sources, the additional computational overhead is modest ($\sim 7$--$14\%$). This approach offers a path to substantially enhance the discovery potential of current and future neutrino telescopes without requiring new detector capabilities.

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