arXiv subjects

Guo-yuan Huang

Publications and source records attributed to Guo-yuan Huang.

At least 19 recordsLinked to original sources

arXiv2026

Rare processes in ultrahigh-energy tau-lepton transport

In cosmic neutrino observatories, charged-lepton transport is a key input for interpreting observables and reconstructing neutrino events. Charged leptons propagating through matter undergo several energy loss processes, such as electron pair production and photonuclear interaction. In this work, we investigate several rare processes in tau-lepton transport, focusing primarily on muon pair production, $τN \to τμ^+μ^- N$, and Primakoff neutral-pion production, $τN \to τπ^0 N$. At EeV energies, we find that the energy loss contributions from muon pair and Primakoff pion production are only $0.6\%$ and $0.2\%$, respectively, of that from electron pair production. Nevertheless, dimuon production may be relevant to tau neutrino searches in underwater and under-ice Cherenkov telescopes. The interaction length for dimuon emission by an EeV tau is only $6~{\rm km}$ in standard rock. Such events may be identified through the lateral separation of dimuon tracks or through a kebab topology if tau decays in the detector.

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arXiv2026

Probing Cosmic Neutrino Background through Parametric Fluorescence

We point out that relic neutrinos from the Big Bang may induce the parametric fluorescence in atomic or molecular systems, which offers a novel way to discover cosmic neutrino background. By coherently scattering with molecular energy levels, a massive neutrino can spontaneously ``decay" into a lighter neutrino and an infrared signal photon, i.e., $ν^{}_{i} + M \to ν^{}_{j} + γ^{}_{\rm S} + M$, where the molecular state $M$ remains unchanged after the scattering. Because the amplitudes of different radiants are matched in phase, the rate is coherently enhanced and proportional to the squared density of ambient dipoles. When the energy transfer from neutrinos coincides with the energy-level difference, the fluorescence will be on resonance. Near the resonance, the rate is proportional to the square of the coherence time $T^{}_{\rm c}$ of the ensemble. For a nominal target volume of $5~{\rm m^3}$ (or $5~{\rm cm^3}$), the signal rate can reach $1~{\rm yr}^{-1}$ for $T^{}_{\rm c} = 10~{\rm ns}$ (or $T^{}_{\rm c} = 10~{\rm μs}$). This event rate appears to be very promising in consideration of an even longer coherence time that is achievable in solid systems.

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arXiv2024

Neutrino-antineutrino Asymmetry of C$ν$B on the Surface of the Round Earth

It has been claimed that the coherent scattering of relic neutrinos with the Earth will result in a neutrino-antineutrino asymmetry of $\mathcal{O}(10^{-4})$ on the Earth surface, which is five orders of magnitude larger than the naive model expectation. In this work we show that this overdensity was overestimated for the perfectly round Earth by solving the exact solution with partial waves. The maximal asymmetry after summing over all the angular modes is only around $10^{-8}$ above the ground. To achieve the proposed asymmetry of $\mathcal{O}(10^{-4})$, a special geography may be needed as the experimental site.

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arXiv2023

Inferring astrophysical neutrino sources from the Glashow resonance

We infer the ultrahigh energy neutrino source by using the Glashow resonance candidate event recently identified by the IceCube Observatory. For the calculation of the cross section for the Glashow resonance, we incorporate both the atomic Doppler broadening effect and initial state radiation $\overlineν^{}_{e} e^- \to W^- γ$, which correct the original cross section considerably. Using available experimental information, we have set a generic constraint on the $\overlineν^{}_{e}$ fraction of astrophysical neutrinos, which excludes the $μ$-damped ${\rm p}γ$ source around $2σ$ confidence level under the assumption that neutrino production is dominated by the $Δ$-resonance. While a weak preference has been found for the pp source, next-generation measurements will be able to distinguish between ideal pp and p$γ$ sources with a high significance assuming an optimistic single power-law neutrino spectrum. The inclusion of multi-pion production at very high energies for the neutrino source can weaken the discrimination power. In this case additional multimessenger information is needed to distinguish between pp and p$γ$ sources.

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arXiv2023

Tritium beta decay with modified neutrino dispersion relations: KATRIN in the dark sea

We explore beta decays in a dark background field, which could be formed by dark matter, dark energy or a fifth force potential. In such scenarios, the neutrino's dispersion relation will be modified by its collective interaction with the dark field, which can have interesting consequences in experiments using tritium beta decays to determine the absolute neutrino mass. Among the most general interaction forms, the (pseudo)scalar and (axial-)vector ones are found to have interesting effects on the spectrum of beta decays. In particular, the vector and axial-vector potentials can induce distinct signatures by shifting the overall electron energy scale, possibly beyond the usually defined endpoint. The scalar and pseudoscalar potentials are able to mimic a neutrino mass beyond the cosmological bounds. We have placed stringent constraints on the dark potentials based on the available experimental data of KATRIN. The sensitivity of future KATRIN runs is also discussed.

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arXiv2023

Probing New Physics at Future Tau Neutrino Telescopes

We systematically investigate new physics scenarios that can modify the interactions between neutrinos and matter at upcoming tau neutrino telescopes, which will test neutrino-proton collisions with energies $ \gtrsim 45~{\rm TeV}$, and can provide unique insights to the elusive tau neutrino. At such high energy scales, the impact of parton distribution functions of second and third generations of quarks (usually suppressed) can be comparable to the contribution of first generation with small momentum fraction, hence making tau neutrino telescopes an excellent facility to probe new physics associated with second and third families. Among an inclusive set of particle physics models, we identify new physics scenarios at tree level that can give competitive contributions to the neutrino cross sections while staying within laboratory constraints: charged/neutral Higgs and leptoquarks. Our analysis is close to the actual experimental configurations of the telescopes, and we perform a $χ^2$-analysis on the energy and angular distributions of the tau events. By numerically solving the propagation equations of neutrino and tau fluxes in matter, we obtain the sensitivities of representative upcoming tau neutrino telescopes, GRAND, POEMMA and Trinity, to the charged Higgs and leptoquark models. While each of the experiments can achieve a sensitivity better than the current collider reaches for certain models, their combination is remarkably complementary in probing the new physics. In particular, the new physics will affect the energy and angular distributions in different ways at those telescopes.

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arXiv2023

Discovery potential of the Glashow resonance in an air shower neutrino telescope

The in-ice or in-water Cherenkov neutrino telescope such as IceCube has already proved its power in measuring the Glashow resonance by searching for the bump around $E^{}_{\rm ν} = 6.3~{\rm PeV}$ arising from the $W$-boson production. In the next few decades, there are many proposals that observe cosmic tau neutrinos with extensive air showers, also known as tau neutrino telescopes. As has been recognized, the air shower telescope is in principle sensitive to the Glashow resonance via the channel $W \to τν^{}_τ$ followed by the tau decay in the air. However, with a thorough numerical analysis we have identified several limitations for those telescopes on hunting the resonance. If ultrahigh-energy neutrinos are dominantly produced from the meson decay, it will be statistically difficult for a rather advanced proposal, such as TAMBO with a geometric area around $500~{\rm km^2}$, to discriminate the Glashow resonance induced by $\overlineν^{}_{e}$ from the intrinsic $ν^{}_τ/\overlineν^{}_τ$ background. The discovery significance is only around $1σ$ considering the flux parameters measured by IceCube as the input. Nevertheless, the significance will be improved to $90\%$ if PeV neutrinos mainly originate from the neutron decay, which is, however, thought to be only a subdominant neutrino source. The presence of new physics can also increase the significance. Compared to the in-ice or in-water telescope, the challenge for the Glashow resonance search is ascribed to several factors: (i) a suppressed branching ratio of $11\%$ for the decay $W \to τν^{}_τ$; (ii) the smearing effect and the reduced acceptance because the daughter neutrino takes away $\langle y \rangle \sim 75\%$ of the energy from the $W$ decay; (iii) a large attenuation effect for Earth-skimming neutrinos with the resonance.

astro-ph.HE↗

arXiv2023

Cosmology-friendly time-varying neutrino masses via the sterile neutrino portal

We investigate a consistent scenario of time-varying neutrino masses, and discuss its impact on cosmology, beta decay, and neutrino oscillation experiments. Such time-varying masses are assumed to be generated by the coupling between a sterile neutrino and an ultralight scalar field, which in turn affects the light neutrinos by mixing. Besides, the scalar could act as an ultralight dark matter candidate. We demonstrate how various cosmological bounds, such as those coming from Big Bang nucleosynthesis, the cosmic microwave background, as well as large scale structures, can be evaded in this model. This scenario can be further constrained using multiple terrestrial experiments. In particular, for beta-decay experiments like KATRIN, non-trivial distortions to the electron spectrum can be induced, even when time-variation is fast and gets averaged out. Furthermore, the presence of time-varying masses of sterile neutrinos will alter the interpretation of light sterile neutrino parameter space in the context of the reactor and gallium anomalies. In addition, we also study the impact of such time-varying neutrino masses on results from the BEST collaboration, which have recently strengthened the gallium anomaly. If confirmed, we find that the time-varying neutrino mass hypothesis could give a better fit to the recent BEST data.

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arXiv2022

Double and multiple bangs at tau neutrino telescopes: A novel probe of sphalerons with cosmogenic neutrinos

In light of the exciting campaign of cosmogenic neutrino detection, we investigate the double and multiple tau bangs detectable at future tau neutrino telescopes. Such events are expected from the Standard Model (SM) higher-order processes, which can be easily identified with broad techniques anticipated at future tau neutrino telescopes. We find that SM perturbative processes can already contribute observable double-bang events to telescopes with a sensitivity of collecting $\mathcal{O}(100)$ cosmogenic neutrino events. The detectable but suppressed rate in fact makes the double and multiple bangs an excellent probe of SM unknowns and possible new physics beyond. As a case study, the nonperturbative sphaleron process, which can copiously produce multiple tau bangs, is explored.

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arXiv2022

Inference of neutrino nature and Majorana CP phases from $0νββ$ decays with inverted mass ordering

Whether the neutrino mass ordering is normal or inverted remains an experimentally open issue in neutrino physics. The knowledge of neutrino mass ordering has great importance for neutrinoless double-beta ($ 0νββ$) decay experiments, which can establish the nature of massive neutrinos, i.e., whether they are Dirac or Majorana fermions. Recently, the KamLAND-Zen 800 measurement has reached for the first time the parameter space of the inverted ordering with a vanishing lightest neutrino mass. By assuming the inverted ordering, we attempt to derive the physical information of the neutrino nature and Majorana CP phases from a negative or positive observation of $ 0νββ$ decays in the near future. Moreover, the possibility of extracting the nuclear matrix element in the case of a positive observation is also examined. To avoid the ambiguity from unknown priors of neutrino masses, we adopt the maximum likelihood method instead of the Bayesian approach usually considered in previous works.

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arXiv2022

Search for Leptophilic Dark Matter at the LHeC

The Large Hadron electron Collider (LHeC) has been designed to push the field of deep inelastic scattering to the high energy and intensity frontier using an intense electron beam with a proton beam from the High Luminosity-Large Hadron Collider. However, LHeC is also a great laboratory for new physics. In this work, we propose a search for dark matter that couples with leptons. This may yield $ej$+ missing energy and $μj$ + missing energy signals that can be potentially observed through simple missing-energy cuts that suppress the Standard Model background. Considering direct dark matter detection and LHC constraints, we show that LHeC can indeed discover a weak scale dark matter fermion for masses up to 350 GeV, which reproduces the correct relic density, and has interesting implications for lepton flavor violation.

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arXiv2022

Neutrino meets ultralight dark matter: $\boldsymbol{0νββ}$ decay and cosmology

We explore the neutrinoless double beta ($0νββ$) decay induced by an ultralight dark matter field coupled to neutrinos. The effect on $0νββ$ decay is significant if the coupling violates the lepton number, for which the $ΔL=2$ transition is directly driven by the dark matter field without further suppression of small neutrino masses. As the ultralight dark matter can be well described by a classical field, the effect features a periodic modulation pattern in decay events. However, we find that in the early Universe such coupling will be very likely to alter the standard cosmological results. In particular, the requirement of neutrino free-streaming before the matter-radiation equality severely constrains the parameter space, such that the future $0νββ$ decay experiments can hardly see any signal even with a meV sensitivity to the effective neutrino mass.

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arXiv2022

Probing Heavy Sterile Neutrinos at Ultrahigh Energy Neutrino Telescopes via the Dipole Portal

The question of how heavy a sterile neutrino can be probed in experiments leads us to investigate the Primakoff production of heavy sterile neutrinos up to PeV masses from ultrahigh-energy neutrinos via the magnetic dipole portal. Despite the suppression from the small magnetic moment, the transition is significantly enhanced by tiny $t$-channel momentum transfers, similar to the resonant production of pions and axions in an external electromagnetic field. Based on the current IceCube measurement of astrophysical neutrinos up to PeV energies, strong constraints can already be derived on the transition magnetic moments of sterile neutrinos up to TeV masses. Moreover, we investigate the sensitivity of future tau neutrino telescopes, which are designed for EeV cosmogenic neutrino detection. We find that sterile neutrino masses as large as $30~{\rm TeV}$ can be probed at tau neutrino telescopes such as GRAND, POEMMA, and Trinity.

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arXiv2021

Probing the $R_{K^{(*)}}$ Anomaly at a Muon Collider

The LHCb measurements of the $μ/ e$ ratio in $B \to K \ell \ell$ decays $(R_{K^{}})$ indicate a deficit with respect to the Standard Model prediction, supporting earlier hints of lepton universality violation observed in the $R_{K^{(*)}}$ ratio. Possible explanations of these $B$-physics anomalies include heavy $Z'$ bosons or scalar and vector leptoquarks mediating $b \to s μ^+ μ^- $. We note that a muon collider can directly measure this process via $μ^+ μ^- \to b \bar s$ and can shed light on the lepton non-universality scenario. Investigating currently discussed center-of-mass energies $\sqrt{s} = 3$, 6 and 10 TeV, we show that the parameter space of $Z'$ and leptoquark solutions to the $R_{K^{(*)}}$ anomalies can be mostly covered. Effective operators explaining the anomalies can be probed with the muon collider setup $\sqrt{s} = 6~{\rm TeV}$ and integrated luminosity $L = 4~{\rm ab^{-1}}$.

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arXiv2021

Tentative sensitivity of future $0νββ$-decay experiments to neutrino masses and Majorana CP phases

In the near future, the neutrinoless double-beta ($0νββ$) decay experiments will hopefully reach the sensitivity of a few ${\rm meV}$ to the effective neutrino mass $|m^{}_{ββ}|$. In this paper, we tentatively examine the sensitivity of future $0νββ$-decay experiments to neutrino masses and Majorana CP phases by following the Bayesian statistical approach. Provided experimental setups corresponding to the sensitivity of $|m^{}_{ββ}| \simeq 1~{\rm meV}$, the null observation of $0νββ$ decays in the case of normal neutrino mass ordering leads to a very competitive bound on the lightest neutrino mass $m^{}_1$. Namely, the $95\%$ credible interval turns out to be $1.6~{\rm meV} \lesssim m^{}_1 \lesssim 7.3~{\rm meV}$ or $0.3~{\rm meV} \lesssim m^{}_1 \lesssim 5.6~{\rm meV}$ when the uniform prior on $m^{}_1/{\rm eV}$ or on $\log^{}_{10}(m^{}_1/{\rm eV})$ is adopted. Moreover, one of two Majorana CP phases is strictly constrained, i.e., $140^\circ \lesssim ρ\lesssim 220^\circ$ for both priors of $m^{}_1$. In contrast, if a relatively worse sensitivity of $|m^{}_{ββ}| \simeq 10~{\rm meV}$ is assumed, the constraint becomes accordingly $0.6~{\rm meV} \lesssim m^{}_1 \lesssim 26~{\rm meV}$ or $0 \lesssim m^{}_1 \lesssim 6.1~{\rm meV}$, while two Majorana CP phases will be essentially unconstrained. In the same statistical framework, the prospects for the determination of neutrino mass ordering and the discrimination between Majorana and Dirac nature of massive neutrinos in the $0νββ$-decay experiments are also discussed. Given the experimental sensitivity of $|m^{}_{ββ}| \simeq 10~{\rm meV}$ (or $1~{\rm meV}$), the strength of evidence to exclude the Majorana nature under the null observation of $0νββ$ decays is found to be inconclusive (or strong), no matter which of two priors on $m^{}_1$ is taken.

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arXiv2021

Solving the Hubble tension without spoiling Big Bang Nucleosynthesis

The Hubble parameter inferred from cosmic microwave background observations is consistently lower than that from local measurements, which could hint towards new physics. Solutions to the Hubble tension typically require a sizable amount of extra radiation $ΔN^{}_{\rm eff}$ during recombination. However, the amount of $ΔN^{}_{\rm eff}$ in the early Universe is unavoidably constrained by Big Bang Nucleosynthesis (BBN), which causes problems for such solutions. We present a possibility to evade this problem by introducing neutrino self-interactions via a simple Majoron-like coupling. The scalar is slightly heavier than $1~{\rm MeV}$ and allowed to be fully thermalized throughout the BBN era. The rise of neutrino temperature due to the entropy transfer via $ϕ\to ν\overlineν$ reactions compensates the effect of a large $ΔN^{}_{\rm eff}$ on BBN. Values of $ΔN^{}_{\rm eff}$ as large as $0.7$ are in this case compatible with BBN. We perform a fit to the parameter space of the model.

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arXiv2021

Precise Values of Running Quark and Lepton Masses in the Standard Model

The precise values of the running quark and lepton masses $m^{}_f(μ)$, which are defined in the modified minimal subtraction scheme ($\overline{\rm MS}$) with $μ$ being the renormalization scale and the subscript $f$ referring to all the charged fermions in the Standard Model (SM), are very useful for the model building of fermion masses and flavor mixing and for the precision calculations in the SM or its new-physics extensions. In this paper, we calculate the running fermion masses by taking account of the up-to-date experimental results collected by Particle Data Group and the latest theoretical higher-order calculations of relevant renormalization-group equations and matching conditions in the literature. The emphasis is placed on the quantitative estimation of current uncertainties on the running fermion masses, and the linear error propagation method is adopted to quantify the uncertainties, which has been justified by the Monte-Carlo simulations. We identify two main sources of uncertainties, i.e., one from the experimental inputs and the other from the truncations at finite-order loops. The correlations among the uncertainties of running parameters can be remarkable in some cases. The final results of running fermion masses at several representative energy scales are tabulated for further applications.

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arXiv2021

Gauged $L^{}_μ{-}L^{}_τ$ at a muon collider

We investigate the sensitivity of the projected TeV muon collider to the gauged $L^{}_μ$-$L^{}_τ$ model. Two processes are considered: $Z'$-mediated two-body scatterings $μ^+ μ^- \to \ell^+ \ell^-$ with $\ell = μ$ or $τ$, and scattering with initial state photon emission, $μ^+ μ^- \to γZ',~Z' \to \ell \overline{\ell}$, where $\ell$ can be $μ$, $τ$ or $ν_{μ/τ}$. We quantitatively study the sensitivities of these two processes by taking into account possible signals and relevant backgrounds in a muon collider experiment with a center-of-mass energy $\sqrt{s} = 3~{\rm TeV}$ and a luminosity $L=1~{\rm ab^{-1}}$. For two-body scattering one can exclude $Z'$ masses $M^{}_{Z'} \lesssim 100~{\rm TeV}$ with $\mathcal{O}(1)$ gauge couplings. When $M^{}_{Z'} \lesssim 1~{\rm TeV} <\sqrt{s}$, one can exclude $g' \gtrsim 2\times 10^{-2}$. The process with photon emission is more powerful than the two-body scattering if $M^{}_{Z'} < \sqrt{s}$. For instance, a sensitivity of $g' \simeq 4 \times 10^{-3}$ can be achieved at $M^{}_{Z'} = 1~{\rm TeV}$. The parameter spaces favored by the $(g-2)^{}_μ$ and $B$ anomalies with $M^{}_{Z'} > 100~{\rm GeV}$ are entirely covered by a muon collider.

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