arXiv subjects

TseChun Wang

Publications and source records attributed to TseChun Wang.

10 recordsLinked to original sources

arXiv2021

Non-standard Neutrino and $Z'$ Interactions at the FASER$ν$ and the LHC

We study the impact of non-standard neutrino interactions in the context of a new gauge boson $Z'$ in neutral-current deep-inelastic scattering performed in ForwArd Search ExpeRiment-$ν$ (FASER$ν$) and in monojet production at the Large Hadron Collider (LHC). We simulate the neutral-current deep-inelastic neutrino-nucleon scattering $νN \rightarrow νN$ at FASER$ν$ in the presence of an additional $Z'$ boson, and estimate the anticipated sensitivities to the gauge coupling in a wide range of $Z'$ mass. At the LHC, we study the effect of $Z'$ on monojet production, which can be enhanced in regions with large missing transverse momenta. We then use the recent results from ATLAS with an integrated luminosity of 139 fb$^{-1}$ to improve the limits on the gauge coupling of $Z'$. We interpret such limits on $Z'$ gauge couplings as bounds on effective non-standard neutrino interactions. We show that the FASER$\rm ν$ and the LHC results cover the medium and high energy scales, respectively, and complement one another.

hep-ph↗

arXiv2021

Constraining sterile neutrinos by core-collapse supernovae with multiple detectors

The eV-scale sterile neutrino has been proposed to explain some anomalous results in experiments, \textit{such as} the deficit of reactor neutrino fluxes and the excess of $\barν_μ\to\barν_e$ in LSND. This hypothesis can be tested by future core-collapse supernova neutrino detection independently since the active-sterile mixing scheme affects the flavor conversion of neutrinos inside the supernova. In this work, we compute the predicted supernova neutrino events in future detectors -- DUNE, Hyper-K, and JUNO -- for neutrinos emitted during the neutronization burst phase when the luminosity of $ν_e$ dominates the other flavors. We find that for a supernova occurring within 10 kpc, the difference in the event numbers with and without sterile neutrinos allows to exclude the sterile neutrino hypothesis at more than $99\%$ confidence level robustly. The derived constraints on sterile neutrinos mixing parameters are comparably better than the results from cosmology and on-going or proposed reactor experiments by more than two orders of magnitude in the $\sin^22θ_{14}$-$Δm_{41}^2$ plane.

hep-ph↗

arXiv2020

Global oscillation data analysis on the $3ν$ mixing without unitarity

We present results of a combined analysis in neutrino oscillations without unitarity assumption in the $3ν$ mixing picture. Constraints on neutrino mixing matrix elements are based on recent data from the reactor, solar and long-baseline accelerator neutrino oscillation experiments. The current data are consistent with the standard $3ν$ scheme. The precision on different matrix elements can be as good as a few percent at $3σ$ CL, and is mainly limited by the experimental statistical uncertainty. The $ν_e$ related elements are the most precisely measured among all sectors with the uncertainties $<20\%$. The measured leptonic CP violation is very close to the one assuming the standard $3ν$ mixing. The deviations on normalization and the unitarity triangle closure are confined within $\mathcal{O}(10^{-3})$, $\mathcal{O}(10^{-2})$ and $\mathcal{O}(10^{-1})$, for $ν_e$, $ν_μ$ and $ν_τ$ sectors, respectively. We look forward to the next-generation neutrino oscillation experiments \textit{such as} DUNE, T2HK, and JUNO, especially the precise measurements on $ν_τ$ oscillations, to significantly improve the precision of unitarity test on the $3ν$ mixing matrix.

hep-ph↗

arXiv2020

Prospects and requirements of opaque detectors in accelerator neutrino experiments

Opaque detectors are a recently proposed novel detector concept where an opaque scintillator aligned with wavelength-shifting fibers is used to enable the discrimination of electron neutrinos and antineutrinos with a rather low energy threshold. In this work, we investigate the potential effects of the enhanced detection capabilities of the opaque detectors in accelerator neutrino experiments. Focusing on the energy threshold, energy resolution, detection efficiency and background suppression in the analysis of electron-like events, we determine whether using opaque detectors could lead to improvements in the CP violation and light sterile neutrino searches in the future accelerator neutrino experiments. We also identify the minimum requirements for the opaque detectors to reach the designated physics goals in the simulated experiments. We find that a 75.6% fraction of $δ_{CP}$ values could be reached for CP violation discovery by 3$σ$ confidence level or better when opaque detectors of 120 kton and 130 kton fiducial masses are used together with neutrino beams from J-PARC and MOMENT, respectively, whereas near detectors placed about 250 m from sources are sufficient to exclude the gallium anomaly at 2$σ$ confidence level.

physics.ins-det↗

arXiv2020

Nonstandard neutrino interactions and mu-tau reflection symmetry

Nonstandard interactions (NSIs), possible subleading effects originating from new physics beyond the Standard Model, may affect the propagation of neutrinos and eventually contribute to measurements of neutrino oscillations. Besides this, $ μ-τ$ reflection symmetry, naturally predicted by non-Abelian discrete flavor symmetries, has been very successful in explaining the observed leptonic mixing patterns. In this work, we study the combined effect of both. We present an $S_4$ flavor model with $μ-τ$ reflection symmetry realized in both neutrino masses and NSIs. Under this formalism, we perform a detailed study for the upcoming neutrino experiments DUNE and T2HK. Our simulation results show that under the $μ-τ$ reflection symmetry, NSI parameters are further constrained and the mass ordering sensitivity is less affected by the presence of NSIs.

hep-ph↗

arXiv2019

Study of a tri-direct littlest seesaw model at MOMENT

The flavour symmetry succeeds in explaining the current global fit results. Flavour-symmetry models can be tested by the future experiments that improve the precision of neutrino oscillation parameters, \textit{such as} the MuOn-decay MEdium baseline NeuTrino beam experiment (MOMENT). In this work, we consider tri-direct littlest seesaw (TDLS) models for a case study, and analyze how much MOMENT can extend our knowledge on the TDLS model. We find that measurements of $θ_{23}$ and $δ$ are crucial for MOMENT to exclude the model at more than $5σ$ confidence level, if the best fit values in the last global analysis result is confirmed. Moreover, the $3σ$ precision of model parameters can be improved at MOMENT by at least a factor of two. Finally, we project the surface at the $3σ$ confidence level from the model-parameter space to the oscillation-parameter space, and find the potential of MOMENT to observe the sum rule between $θ_{23}$ and $δ$ predicted by TDLS.

hep-ph↗

arXiv2019

Invisible neutrino decays at the MOMENT experiment

We investigate invisible decays of the third neutrino mass eigenstate in future accelerator neutrino experiments using muon-decay beams such as MuOn-decay MEdium baseline NeuTrino beam experiment (MOMENT). MOMENT has an outstanding performance to measure the deficit or excess in the spectra caused by neutrino decays, especially in $ν_μ$ and $\barν_μ$ disappearance channels. Such an experiment will improve the constraints of the neutrino lifetime $τ_3$. Compared with exclusion limits in the current accelerator neutrino experiments T2K and NOvA under the stable $ν$ assumption, we expect that MOMENT gives the bound of $τ_3/m_3\ge1.46\times10^{-11}$~s/eV at $3σ$ confidence level, which is better than their recent limits: $τ_3/m_3\ge 7\times10^{-13}$~s/eV in NOvA and $τ_3/m_3\ge 1.41\times10^{-12}$~s/eV in T2K. The non-decay scenario is expected to be excluded by MOMENT at the $>3σ$ confidence level, if the best fit results in T2K and NOvA are confirmed. We further find that reducing systematic uncertainties is slightly more important than the running time. Finally, we find very little correlations between $τ_3/m_3$ and other oscillation parameters, which point to an advantage of MOMENT to measure $τ_3/m_3$.

hep-ph↗

arXiv2019

Neutrino non-standard interactions as a portal to test flavour symmetries

Imposing non-Abelian discrete flavour symmetries to neutrino non-standard interactions (NSIs) is discussed for the first time. For definiteness, we choose $A_4$ as the flavour symmetry, which is subsequently broken to the residual symmetry $Z_2$ in the neutrino sector. We provide a general discussion on flavour structures of NSIs from higher-dimensional operators ($d\leqslant8$) without inducing unnecessary tree-level 4-charged-fermion interactions. Both $A_4$- and $Z_2$-motivated NSI textures are obtained. UV completions of higher-dimensional operators lead to extra experimental constraints on NSI textures. We study the implementation of matter-effect NSIs in DUNE from phenomenological point of view, and discover that DUNE can test $A_4$ with a high level of statistics. We also present exclusion limits of sum rules suggested by UV-complete models. Our result shows that the NSI effects, though predicted to be small for DUNE, could provide useful information that might extend our understanding of the flavour symmetry.

hep-ph↗

arXiv2017

Sensitivities and synergies of DUNE and T2HK

Long-baseline neutrino oscillation experiments, in particular Deep Underground Neutrino Experiment (DUNE) and Tokai to Hyper-Kamiokande (T2HK), will lead the effort in the precision determination of the as yet unknown parameters of the leptonic mixing matrix. In this article, we revisit the potential of DUNE, T2HK and their combination in light of the most recent experimental information. As well as addressing more conventional questions, we pay particular attention to the attainable precision on δ, which is playing an increasingly important role in the physics case of the long-baseline programme. We analyse the complementarity of the two designs, identify the benefit of a programme comprising distinct experiments and consider how best to optimise the global oscillation programme. This latter question is particularly pertinent in light of a number of alternative design options which have recently been mooted: a Korean second detector for T2HK and different beams options at DUNE. We study the impact of these options and quantify the synergies between alternative proposals, identifying the best means of furthering our knowledge of the fundamental physics of neutrino oscillation.

hep-ph↗

arXiv2016

Precision neutrino experiments vs the Littlest Seesaw

We study to what extent upcoming precision neutrino oscillation experiments will be able to exclude one of the most predictive models of neutrino mass and mixing: the Littlest Seesaw. We show that this model provides a good fit to current data, predicting eight observables from two input parameters, and provide new assessments of its predictions and their correlations. We then assess the ability to exclude this model using simulations of upcoming neutrino oscillation experiments including the medium-distance reactor experiments JUNO and RENO-50 and the long-baseline accelerator experiments DUNE and T2HK. We find that an accurate determination of the currently least well measured parameters, namely the atmospheric and solar angles and the CP phase $δ$, provide crucial independent tests of the model. For $θ_{13}$ and the two mass-squared differences, however, the model's exclusion requires a combination of measurements coming from a varied experimental programme. Our results show that the synergy and complementarity of future experiments will play a vital role in efficiently discriminating between predictive models of neutrino flavour, and hence, towards advancing our understanding of neutrino oscillations in the context of the flavour puzzle of the Standard Model.

hep-ph↗