arXiv subjects

Qinrui Liu

Publications and source records attributed to Qinrui Liu.

At least 19 recordsLinked to original sources

arXiv2026

Probing Neutrino Flavor Composition with the Glashow Resonance at Tau Air-Shower Neutrino Telescopes

The flavor composition of high-energy astrophysical neutrinos encodes information about their production and propagation. The Glashow resonance, $\barν_e + e^-\to W^-$, provides a unique way to distinguish antineutrinos from neutrinos and thereby extends the reach of flavor composition studies. Proposed tau air-shower neutrino telescopes target Earth-skimming and mountain-skimming $ν_τ$ above a PeV, but through the decay $W^-\to \barν_τ+τ^-$ they are also sensitive to $\barν_e$. These experiments can therefore measure the ratio of $\barν_e$ to $ν_τ+\barν_τ$ fluxes. We evaluate this prospect with explicit simulations and project sensitivities for TAMBO and TRINITY, assuming 10 years of operation. We find that mountain-skimming geometries yield substantially higher $\barν_e$ acceptance than Earth-skimming ones due to the shorter path length in rock. For standard astrophysical source scenarios, our projections show that differentiating $pp$ and $pγ$ production, including their muon-damped scenarios, is challenging with a standalone measurement by tau air-shower experiments in their currently designed configurations, though optimistically the flux ratio can be constrained to $\lesssim$2 at 1$σ$. A $\barν_e$-rich flux, as expected from neutron-decay sources or from certain new physics models, would stand out from the standard pion-production scenarios and can otherwise be constrained.

hep-ph↗

arXiv2026

Informatics Modeling of High Tg Polymers: Assessing the Role of Processing versus Chemistry

Despite the advances in structure-based modeling of polymer properties, accurately predicting glass transition temperature (Tg) is still challenging for polymers whose behavior is strongly influenced by intermolecular interactions and processing conditions. We previously developed a machine-learning model based on polymer topological descriptors to predict Tg. The model performed well and was based solely on the chemistry and structure of the polymer without any inclusion of processing parameters. In this work, we have extended that work by first applying that same model to a larger range of polymers and second by integrating processing parameters into the feature set. The chemistry-based model still demonstrates consistent predictive performance for most polymers, indicating that Tg is indeed primarily chemistry and structure driven and not strongly impacted by processing. However, several polymers exhibited deviations between predicted and experimental Tg values. Detailed analysis reveals that these differences are related to strong intermolecular interactions and processing-dependent factors, particularly for polymers prepared by solution casting and high temperature annealing. These results demonstrate that molecular topology provides a strong foundation for Tg prediction; however, this approach also screens out those classes of polymers for with processing conditions play an important role.

cond-mat.mtrl-sci↗

arXiv2026

Are neutrinos Majorana? Fixed-target and high-energy astrophysical searches decide

Determining whether the neutrino is a Dirac or Majorana fermion remains a fundamental open question. Conventional searches rely on neutrinoless double beta decay, but this electron-only channel suffers from blind spots. We propose a new, complementary probe to overcome this limitation. A heavy neutral lepton (HNL) triggers a high-energy shift in how the active neutrino flavors ($ν_e$, $ν_μ$, $ν_τ$) mix -- but only if the neutrinos are Majorana. For GeV-scale HNLs, the upcoming beam-dump experiment SHiP can discover the HNL and measure how it mixes with the active flavors. Separately, the scattering of TeV--PeV astrophysical neutrinos can resolve the HNL, revealing a shift in the proportions of each flavor arriving at Earth that could be detected by neutrino telescopes, regardless of the unknown flavor composition at the astrophysical neutrino sources. Because this flavor shift is most sensitive to the muon and tau sectors, it bypasses the blind spots of neutrinoless double beta decay. A correlated signal at SHiP and next-generation neutrino telescopes would prove that neutrinos are Majorana; its absence would point to them being Dirac.

hep-ph↗

arXiv2026

Astrophysical bounds on the high-energy evolution of neutrino mixing

While conventional oscillation experiments measure neutrino mixing parameters with high precision, these measurements are strictly confined to sub-TeV scales. At higher energies, renormalization-group effects can cause these parameters to evolve with the transferred momentum, $Q$. High-energy and ultra-high-energy astrophysical neutrinos, spanning TeV to EeV energies, probe high values of $Q$ unreachable by conventional experiments, offering an unprecedented test of high-energy mixing. We use the flavor composition of these neutrinos -- the relative proportions of $ν_e$, $ν_μ$, and $ν_τ$ -- to constrain this evolution, both phenomenologically and within dimension-6 Standard Model Effective Field Theory. We account for astrophysical uncertainties -- an unavoidable requirement to obtain realistic results, even though this weakens the bounds. Although present IceCube measurements lack the sensitivity to detect this running, we forecast that upcoming multi-detector combinations will place unprecedented bounds on the high-energy evolution of neutrino mixing.

hep-ph↗

arXiv2026

Measuring neutrino mixing above 1 TeV with astrophysical neutrinos

We assess the potential for measuring neutrino mixing parameters at energies above 1~TeV, for the first time, using the flavor composition of TeV--PeV astrophysical neutrinos, i.e., the proportion of $ν_e$, $ν_μ$, and $ν_τ$. Today, flavor measurements inferred from the 11.4-year IceCube Medium Energy Starting Events sample are insufficient to constrain the mixing parameters due to limited statistics, challenges in flavor identification, and uncertainty in neutrino production. Yet, upcoming multi-neutrino-telescope observations -- even using only existing telescopes -- may achieve sensitivity to $θ_{23}$ and $θ_{13}$ when combined with traditional oscillation experiments. We establish the current status and future prospects for testing the three-flavor mixing framework in the previously unexplored TeV--PeV regime and quantify the minimum detectable size of flavor-modifying beyond-Standard-Model effects, providing a roadmap for high-energy neutrino mixing measurements.

hep-ph↗

arXiv2026

Coupled Time-Dependent Proton Acceleration and Leptonic-Hadronic Radiation in Turbulent Supermassive Black Hole Coronae

Turbulent coronae of supermassive black holes can accelerate non-thermal particles to high energies and produce observable radiation, but capturing this process is challenging due to comparable timescales of acceleration, cooling, and the development of cascades. We present a time-dependent numerical framework that self-consistently couples proton acceleration--modeled by the Fokker-Planck equation--with leptonic-hadronic radiation. For the neutrino-emitting Seyfert galaxy NGC 1068, we reproduce the neutrino spectrum observed by IceCube, while satisfying gamma-ray constraints. We also consider a transient corona scenario, potentially emerging in tidal disruption events like AT 2019dsg, and show that cascade feedback on proton cooling can impact proton acceleration and radiation processes in weaker coronae, producing delayed optical/ultraviolet, X-ray, and neutrino emissions of $\mathcal O(100~\rm d)$. This flexible tool efficiently models multi-messenger signals from both steady and transient astrophysical sources, providing insights in combining particle acceleration and radiation mechanisms.

astro-ph.HE↗

arXiv2025

Constraints on Heavy Asymmetric and Symmetric Dark Matter from the Glashow Resonance

The decay of asymmetric dark matter (ADM) can lead to distinct neutrino signatures characterized by an asymmetry between neutrinos and antineutrinos. In the high-energy regime, the Glashow resonant interaction $\barν_{e} + e^{-} \rightarrow W^{-}$ yields an increase in sensitivity to the neutrino flux, and stands out as the only way of discerning the antineutrino component in the diffuse high-energy astrophysical neutrino flux. This offers a unique opportunity in the search for dark matter with masses above the PeV scale. We examine the neutrino signal stemming from ADM decay and set the first stringent constraints on ADM lifetime $τ_X$. For ADM with mass $m_X\gtrsim 10$~PeV, we {exclude} $τ_X\lesssim 10^{29}$s using the data from the recent IceCube search for Glashow resonance events. Our projections further show that sensitivities at the forthcoming IceCube-Gen2 could approach $10^{30}$s, depending on the decay channel. The current constraints on symmetric dark matter decay to neutrinos are also improved by up to a factor of 3 thanks to the Glashow resonance.

hep-ph↗

arXiv2025

Illuminating Very Heavy Dark Matter in the Earth with Tau Neutrinos

Dark matter accumulates in the center of the Earth as the planet plows through the dark matter halo in the Milky Way. Possible annihilation of dark matter to Standard Model particles can be probed in indirect dark matter searches. Among possible messengers, neutrinos are uniquely ideal as they can escape dense regions. Therefore, neutrino telescopes, with their large volume and broad energy exposures, offer new opportunities to search for dark matter signals from the center of the Earth. However, such studies have been restricted to dark matter masses below $\sim$ PeV as the Earth becomes opaque to very-high-energy neutrinos. In this study, we demonstrate that neutrino telescopes operating at TeV-PeV energies can probe very heavy dark matter particles if they annihilate to tau neutrinos or tau leptons. Here, we report upper limits on the spin-independent dark matter-nucleon cross section for masses between $10^5$ GeV and $10^{10}$ GeV by using 7.5 years of IceCube high-energy starting event observations. Our results motivate detailed analyses in IceCube and other upcoming neutrino telescopes in the Northern Hemisphere.

hep-ph↗

arXiv2024

Dissipative Dark Cosmology: From Early Matter Dominance to Delayed Compact Objects

We demonstrate a novel mechanism for producing dark compact objects and black holes through a dark sector, where all the dark matter can be dissipative. Heavy dark sector particles with masses above $10^4$ GeV can come to dominate the Universe and yield an early matter-dominated era before Big Bang Nucleosynthesis (BBN). Density perturbations in this epoch can grow and collapse into tiny dark matter halos, which cool via self interactions. The typical halo size is set by the Hubble length once perturbations begin growing, offering a straightforward prediction of the halo size and evolution depending on ones choice of dark matter model. Once these primordial halos have formed, a thermal phase transition can then shift the Universe back into radiation domination and standard cosmology. These halos can continue to collapse after BBN, resulting in the late-time formation of fragmented dark compact objects and sub-solar mass primordial black holes. We find that these compact objects can constitute a sizable fraction of all of dark matter. The resulting fragments can have masses between $10^{20}$ g to $10^{32}$ g, with radii ranging from $10^{-2}$ m to $10^5$ m, while the black holes can have masses between $10^{8}$ g to $10^{34}$ g. Furthermore, a unique feature of this model is the late-time formation of black holes which can evaporate today. We compare where these objects lie with respect to current primordial black hole and and massive (astrophysical) compact halo object constraints.

hep-ph↗

arXiv2024

Cosmic Ray-Boosted Dark Matter at IceCube

Cosmic ray (CR) upscattering of dark matter is considered as one of the most straightforward mechanisms to accelerate ambient dark matter, making it detectable at high threshold, large volume experiments. In this work, we revisit CR upscattered dark matter signals at the IceCube detector, focusing on lower energy data than was considered before. We consider both scattering with electrons and nuclei. In the latter, we include both elastic and deep-inelastic scattering computations. As concrete examples, we consider two benchmark models; Fermion dark matter with vector and scalar mediators. We compare our model projections with the most current constraints and show that the IceCube detector can detect CR-boosted dark matter especially with masses below $\sim$ 100 keV when scattering with electrons and $\sim$ MeV in the nucleon scattering case.

hep-ph↗

arXiv2024

Neutrino and Gamma-Ray Signatures of Inelastic Dark Matter Annihilating outside Neutron Stars

We present a new inelastic dark matter search: neutron stars in dark matter-rich environments capture inelastic dark matter which, for interstate mass splittings between about $45 - 285 \ \rm MeV$, will annihilate away before becoming fully trapped inside the object. This means a sizable fraction of the dark matter particles can annihilate while being outside the neutron star, producing neutron star-focused gamma-rays and neutrinos. We analyze this effect for the first time and target the neutron star population in the Galactic Center, where the large dark matter and neutron star content makes this signal most significant. Depending on the assumed neutron star and dark matter distributions, we set constraints on the dark matter-nucleon inelastic cross-section using existing H.E.S.S. observations. We also forecast the sensitivity of upcoming gamma-ray and neutrino telescopes to this signal, which can reach inelastic cross-sections as low as $\sim 2 \times 10^{-47} \ \rm cm^2$.

hep-ph↗

arXiv2023

Identifying Energy-Dependent Flavor Transitions in High-Energy Astrophysical Neutrino Measurements

The flavor composition of TeV--PeV astrophysical neutrinos, i.e., the proportion of neutrinos of different flavors in their flux, is a versatile probe of high-energy astrophysics and fundamental physics. Because flavor identification is challenging and the number of detected high-energy astrophysical neutrinos is limited, so far measurements of the flavor composition have represented an average over the range of observed neutrino energies. Yet, this washes out the potential existence of changes in the flavor composition with energy and weakens our sensitivity to the many models that posit them. For the first time, we measure the energy dependence of the flavor composition, looking for a transition from low to high energies. Our present-day measurements, based on the 7.5-year public sample of IceCube High-Energy Starting Events (HESE), find no evidence of a flavor transition. The observation of HESE and through-going muons jointly by next-generation neutrino telescopes Baikal-GVD, IceCube-Gen2, KM3NeT, P-ONE, TAMBO, and TRIDENT may identify a flavor transition around 200TeV by 2030. By 2040, we could infer the flavor composition with which neutrinos are produced with enough precision to establish the transition from neutrino production via the full pion decay chain at low energies to muon-damped pion decay at high energies.

astro-ph.HE↗

arXiv2023

New bounds on light millicharged particles from the tip of the red-giant branch

Stellar energy loss is a sensitive probe of light, weakly coupled dark sectors, including ones containing millicharged particles (MCPs). The emission of MCPs can affect stellar evolution, and therefore can alter the observed properties of stellar populations. In this work, we improve upon the accuracy of existing stellar limits on MCPs by self-consistently modelling (1) the MCP emission rate, accounting for all relevant in-medium effects and production channels, and (2) the evolution of stellar interiors (including backreactions from MCP emission) using the MESA stellar evolution code. We find MCP emission leads to significant brightening of the tip of the red-giant branch. Based on photometric observations of 15 globular clusters whose bolometric magnitudes are inferred using parallaxes from Gaia astrometry, we obtain robust bounds on the existence of MCPs with masses below 100 keV.

hep-ph↗

arXiv2023

Searching for High-Energy Neutrino Emission from Seyfert Galaxies in the Northern Sky with IceCube

The recent detection of TeV neutrino emission from the nearby active galaxy NGC 1068 by IceCube suggests that AGN could make a sizable contribution to the total high-energy cosmic neutrino flux. The absence of TeV gamma rays from NGC 1068, indicates neutrino production originates in the innermost region of the AGN. Disk-corona models predict a correlation between neutrinos and keV X-rays in Seyfert galaxies, a subclass of AGN to which NGC 1068 belongs. Using 10 years of IceCube through-going track events, we report results from searches for neutrino signals from 27 additional sources in the Northern Sky by studying both the generic single power-law spectral assumption and spectra predicted by the disk-corona model. Our results show excesses of neutrinos associated with two sources, NGC 4151 and CGCG 420-015, at 2.7$σ$ significance, and at the same time constrain the collective neutrino emission from our source list.

astro-ph.HE↗

arXiv2023

Search for TeV Neutrinos from Seyfert Galaxies in the Southern Sky using Starting Track Events in IceCube

Supermassive black holes (SMBHs) power active galactic nuclei (AGN). The vicinity of the SMBH has long been proposed as the potential site of particle acceleration and neutrino production. Recently, IceCube reported evidence of neutrino emission from the Seyfert II galaxy NGC 1068. The absence of a matching flux of TeV gamma rays suggests that neutrinos are produced where gamma rays can efficiently get attenuated, for example, in the hot coronal environment near the SMBH at the core of the AGN. Here, we select the intrinsically brightest (in X-ray) Seyfert galaxies in the Southern Sky from the BAT AGN Spectroscopic Survey (BASS) and search for associated neutrinos using starting track events in IceCube. In addition to the standard power law flux assumption, we leverage a dedicated disc-corona model of neutrino production in such an environment to improve the discovery potential of the search. In this contribution, we report on the expected performance of our searches for neutrinos from these Seyfert galaxies.

astro-ph.HE↗

arXiv2023

Probing neutrino production in high-energy astrophysical neutrino sources with the Glashow Resonance

The flavor composition of high-energy neutrinos carries important information about their birth. However, the two most common production scenarios, $pp$ (hadronuclear) and $pγ$ (photohadronic) processes, lead to the same flavor ratios when neutrinos and antineutrinos cannot be distinguished. The Glashow resonant interaction $\barν_e+e^- \rightarrow W^-$ becomes a window to differentiate the antineutrino contribution from the total diffuse neutrino flux, thus lifting this degeneracy. We examine the power of Glashow resonant events in measuring the fraction of the $\barν_e$ flux with current IceCube data, and produce projected sensitivities based on the combined exposure of planned Cherenkov neutrino telescopes around the globe. We find that $pp$ and $pγ$ can be distinguished at a 2$σ$ significance level in the next decades, in both an event-wise analysis and a more conservative statistical analysis, even with pessimistic assumptions on the spectral index of the astrophysical flux. Finally, we consider the sensitivity of future experiments to mixed production mechanisms.

astro-ph.HE↗

arXiv2021

Searching for time-dependent high-energy neutrino emission from X-ray binaries with IceCube

X-ray binaries are long-standing source candidates of Galactic cosmic rays and neutrinos. The compact object in a binary system can be the site for cosmic-ray acceleration, while high-energy neutrinos can be produced by the interactions of cosmic rays in the jet of the compact object, the stellar wind, or the atmosphere of the companion star. We report a time-dependent study of high-energy neutrinos from X-ray binaries with IceCube using 7.5 years of muon neutrino data and X-ray observations. In the absence of significant correlation, we report upper limits on the neutrino fluxes from these sources and provide a comparison with theoretical predictions.

astro-ph.HE↗

arXiv2020

$χ$aro$ν$: a tool for neutrino flux generation from WIMPs

Indirect searches for signatures of corpuscular dark matter have been performed using all cosmic messengers: gamma rays, cosmic rays, and neutrinos. The search for dark matter from neutrinos is of particular importance since they are the only courier that can reach detectors from dark matter processes in dense environments, such as the core of the Sun or Earth, or from the edge of the observable Universe. In this work, we introduce $χ$aro$ν$, a software package that, in the spirit of its mythological Greek namesake $χ\acuteαρων$, bridges the dark sector and Standard Model by predicting neutrino fluxes from different celestial dark matter agglomerations. The flux at the point of production is either computed internally by $χ$aro$ν$ or is taken from user supplied tables. $χ$aro$ν$ then propagates this flux through vacuum or dense media and returns the expected neutrino yield at an observer's location. In developing $χ$aro$ν$, we have revisited and updated the production of neutrinos in dense media, updated the propagation of high-energy neutrinos, and studied the sources of uncertainty in neutrino transport. This package is coupled to a new calculation that includes electroweak corrections resulting in the most up-to-date and complete repository of neutrino fluxes from dark matter decay and annihilation over the energy range of 1 GeV to 10 PeV coming from the Earth, the Sun, and the Galactic halo.

hep-ph↗