arXiv subjects

Pouya Bakhti

Publications and source records attributed to Pouya Bakhti.

At least 19 recordsLinked to original sources

arXiv2026

The $\nu$EYE Neutrino Telescope: Conceptual Design Report

The $\bf\nu EYE$ neutrino project leverages the existing large pit at Yemilab located in South Korea, to reveal the existence of sterile neutrino, the up-turn of the neutrinos from the Sun, and the first minimum of the neutrino oscillation over distances on the order of tens of kilometers for the first time. This initiative is expected to facilitate a wide range of significant scientific and technological advancements within both South Korean and international communities engaged in neutrino science and technology. The $\bf\nu EYE$ aims to investigate the largely unexplored sector of almost-massless lepton in the elementary particle physics in detail. The emphasis will be placed on the study of real time nuclear processes and reactions involving possible sterile neutrinos on timescales down to nanoseconds in ultra-high intense or radioactive neutrino beams for the first time in the world; the $\bf\nu EYE$ looks at to-be universal oscillation (``up-turn'' in the electron neutrino survival probability) of neutrinos predicted by the three neutrino oscillation paradigm. This will confirm or deny our current understanding on the particle interactions of the lepton sector; and measurement of the first oscillation minimum between the first and second neutrinos in mass.

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arXiv2025

Revisiting Reactor Anti-Neutrino 5 MeV Bump with $^{13}$C Neutral-Current Interaction

For the first time, we comprehensively examine the potential of a neutral-current interaction of reactor neutrino with $^{13}$C emitting a 3.685 MeV photon to identify the origin of the 5 MeV bump in reactor antineutrino spectra observed through the inverse beta decay (IBD) process. This anomaly may be due to new physics, reactor antineutrino flux inaccuracies, or IBD systematics. The 3.685 MeV photon released during the de-excitation of $^{13}$C$^\ast$ to its ground state is observable in liquid scintillator detectors. Remarkably, we confirm the powerfulness of our proposal by completely ruling out a new physics scenario explaining the bump from the existing NEOS data. We also explore the potential of current and forthcoming experiments, including solar neutrino studies at JUNO, pion and muon decay-at-rest experiments at OscSNS, and isotope decay-at-rest studies at Yemilab, to measure the cross-section precisely enough to distinguish the expected bump and the theoretical flux models via our channel. Additionally, we propose a novel method to track the time evolution of reactor isotopes by analyzing the $^{13}$C signal, which yields critical insights into the contributions of $^{235}$U and $^{239}$Pu to the bump, acting as a robust tool.

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arXiv2025

New Physics Opportunities at Neutrino Facilities: BSM Physics at Accelerator, Atmospheric, and Reactor Neutrino Experiments

Since the discovery of the Higgs boson, the long-standing task at hand in particle physics is the search for new physics beyond the Standard Model, which accounts for only about 5\% of the Universe. In light of this situation, the neutrino sector has drawn significant attention due to neutrino oscillations, which require physics beyond the Standard Model and have prompted a wide array of active and planned experimental programs. Notably, neutrino facilities offer substantial potential to search for new physics beyond neutrino oscillations, owing to their precision measurement capabilities, diverse experimental configurations, and various neutrino sources. This white paper summarizes the landscape of new physics that can be probed at current and future neutrino experiments, categorized into laboratory-produced and cosmogenic signals. We discuss recent experimental results interpreted through the lens of new physics, as well as detailed plans and projected sensitivities of next-generation facilities. This summary is based on presentations from the 4th Workshop on New Physics Opportunities in Neutrino Facilities (NPN 2024), held at IBS in Daejeon, Korea, on June 3-5, 2024. Particular emphasis is placed on accelerator-based neutrino experiments and a range of neutrino programs in East Asia. We also outline key tasks necessary to realize the promising new physics opportunities ahead.

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arXiv2023

Uncovering Secret Neutrino Interactions at Tau Neutrino Experiments

We investigate the potential of future tau neutrino experiments for identifying the $ν_τ$ appearance in probing secret neutrino interactions. The reference experiments include the DUNE far detector utilizing the atmospheric data, which is for the first time in probing the secret interactions, the Forward Liquid Argon Experiment (FLArE100) detector at the Forward Physics Facility (FPF), and emulsion detector experiments such as SND@LHC, AdvSND, FASER$ν$2, and SND@SHiP. For concreteness, we consider a reference scenario in which the hidden interactions among the neutrinos are mediated by a single light gauge boson $Z'$ with a mass at most below the sub-GeV scale and an interaction strength $g_{αβ}$ between the active neutrinos. We confirm that these experiments have the capability to significantly enhance the current sensitivities on $g_{αβ}$ for $m_{Z'} \lesssim 500$ MeV due to the production of high energy neutrinos and excellent ability to detect tau neutrinos. Our analysis highlights the crucial role of downward-going DUNE atmospheric data in the search for secret neutrino interactions because of the rejection of backgrounds dominated in the upward-going events. Specifically, 10 years of DUNE atmospheric data can provide the best sensitivities on $g_{αβ}$ which is about two orders of magnitude improvement. In addition, the beam-based experiments such as FLArE100 and FASER$ν$2 can improve the current constraint on $g_{eτ}$ and $g_{μτ}$ by more than an order of magnitude after the full running of the high luminosity LHC with the integrated luminosity of 3 ab$^{-1}$. For $g_{eμ}$ and $g_{ee}$ the SHiP experiment can play the most important role in the high energy region of $E> few~100$ MeV.

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arXiv2023

Physics Potential of a Few Kiloton Scale Neutrino Detector at a Deep Underground Lab in Korea

The demand for underground labs for neutrino and rare event search experiments has been increasing over the last few decades. Yemilab, constructed in October 2022, is the first deep ($\sim$1~km) underground lab dedicated to science in Korea, where a large cylindrical cavern (D: 20~m, H: 20~m) was excavated in addition to the main caverns and halls. The large cavern could be utilized for a low background neutrino experiment by a liquid scintillator-based detector (LSC) where a 2.26 kiloton LS target would be filled. It's timely to have such a large but ultra-pure LS detector after the shutdown of the Borexino experiment so that solar neutrinos can be measured much more precisely. Interesting BSM physics searches can be also pursued with this detector when it's combined with an electron linac, a proton cyclotron (IsoDAR source), or a radioactive source. This article discusses the concept of a candidate detector and the physics potential of a large liquid scintillator detector.

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arXiv2023

Exploring Solar Neutrino Oscillation Parameters with LSC at Yemilab and JUNO

We investigate the sensitivities of the liquid scintillator counter (LSC) at Yemilab and JUNO to solar neutrino oscillation parameters, focusing on $θ_{12}$ and $Δm^2_{21}$. We compare the potential of JUNO with LSC at Yemilab utilizing both reactor and solar data in determining those parameters. We find that the solar neutrino data of LSC at Yemilab is highly sensitive to $θ_{12}$ enabling its determination with exceptional precision. Our study also reveals that if $Δm^2_{21}$ is larger, with a value close to the best fit value of KamLAND, JUNO reactor data will have about two times better precision than the reactor LSC at Yemilab. On the other hand, if $Δm^2_{21}$ is smaller and closer to the best fit value of solar neutrino experiments, the precision of the reactor LSC at Yemilab will be better than JUNO.

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arXiv2022

Non-Standard Interaction of atmospheric neutrino in future experiments

We show the prospects of probing neutral-current non-standard interaction (NSI) in the propagation of atmospheric neutrinos in future large-volume neutrino experiments including DUNE, HK, KNO, and ORCA. For DUNE, we utilize its ability of identifying the tau neutrino event and combine the $ν_τ$ appearance with the $ν_μ$ disappearance. Based on our simulated results, the ten years of data taking of the atmospheric neutrinos can enormously improve the bounds on the NSI parameters $\varepsilon_{μτ}, | \varepsilon_{μμ} - \varepsilon_{ττ} |$, $\varepsilon_{e μ}$, $\varepsilon_{e τ}$ and $| \varepsilon_{μμ} - \varepsilon_{e e} |$ by a couple of orders of magnitudes. In addition, we show the expected correlations between the CP-violation phase $δ_{CP}$ and the NSI parameters $\varepsilon_{eμ}, \varepsilon_{eτ}$, and $|\varepsilon_{ee} - \varepsilon_{μμ}|$ and confirm the potentials of DUNE, HK, KNO (combined with HK) in excluding the "No CP violation" hypothesis at 1$σ$, 2$σ$, and 3$σ$, respectively.

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arXiv2022

The Forward Physics Facility at the High-Luminosity LHC

High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe Standard Model (SM) processes and search for physics beyond the Standard Model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential.

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arXiv2021

Sensitivities to secret neutrino interaction at FASER$ν$

We study the impact of the coupling of neutrinos with a new light neutral gauge boson, $Z^\prime$, with a mass of less than 500 {\rm MeV} in FASER$ν$ experiment. Scenarios in which a light gauge boson is coupled to neutrinos are motivated within numerous contexts which are designed to explain various anomalies in particle physics and cosmology. This interaction leads to a new decay mode for charged mesons to a light lepton plus neutrino and $Z^{\prime}$, ($π^+(K^+)\to e^+ νZ^\prime$) followed by the subsequent decay of $Z^\prime$ into the pair of neutrino and anti-neutrino, ($Z^\prime \to ν\barν$). FASER$ν$, the Forward Search Experiment at the LHC, has the potential to detect collider neutrinos for the first time. In particular, the FASER$ν$ emulsion detector will provide the opportunity to detect $τ$-neutrinos and to measure their energies. Using this ability of FASER$ν$ emulsion detector, we investigate the potential of FASER$ν$ experiment and the proposed upgraded version of this experiment, FASER2$ν$, to constrain the coupling of a neutrino with the light gauge boson.

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arXiv2021

Discovery potential of FASER$ν$ with contained vertex and through-going events

FASER$ν$ is a newly proposed detector whose main mission is to detect the neutrino flux from the collision of the proton beams at the ATLAS Interaction Point (IP) during the run III of the LHC in 2022-2024. We show that this detector can also test certain beyond standard model scenarios, especially the ones in which the neutrino interaction with matter fields can produce new unstable particles decaying back into charged leptons. Models of this kind are motivated by the MiniBooNE anomaly. We show that, if the new physics involves multi-muon production by neutrinos scattering off matter fields, including the neutrino flux interactions in the rock before the detector in the analysis ({\it i.e.,} accounting for the through-going muon pairs) can significantly increase the effective detector mass and its sensitivity to new physics. We propose a concrete model that can give rise to such a multi-muon signal.

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arXiv2020

Sensitivities of future reactor and long-baseline neutrino experiments to NSI

We investigate the potential of the next generation long-baseline neutrino experiments DUNE and T2HK as well as the upcoming reactor experiment JUNO to constrain Non-Standard Interaction (NSI) parameters. JUNO is going to provide the most precise measurements of solar neutrino oscillation parameters as well as determining the neutrino mass ordering. We study how the results of JUNO combined with those of long-baseline neutrino experiments such as DUNE and T2HK can help to determine oscillation parameters and to constrain NSI parameters. We present excluded regions in NSI parameter space, $ε_{αβ}$ assuming Standard Model (SM) as the null hypothesis. We further explore the correlations between the NSI parameters and CP-violation phase.

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arXiv2020

Unravelling the richness of dark sector by FASER$ν$

FASER$ν$ is a newly proposed experiment which will take data in run III of the LHC during 2021-2023. It will be located in front of the FASER detector, 480~m away from the ATLAS interaction point in the forward direction. Its main goal is to detect neutrinos of all flavors produced at the interaction point with superb precision in reconstructing charged tracks. This capability makes FASER$ν$ an ideal setup for uncovering the pattern and properties of a light dark sector. We demonstrate this capability for a well-motivated class of models with a dark matter candidate of mass around a few GeV. Dark matter annihilates to a pair of intermediate neutral particles that subsequently decay into the standard model charged fermions. We show how FASER$ν$ can shed light on the structure of the dark sector by unravelling the decay chain within such models.

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arXiv2020

Oscillation tomography of the Earth with solar neutrinos and future experiments

We study in details the Earth matter effects on the boron neutrinos from the Sun using recently developed 3D models of the Earth. The models have a number of new features of the density profiles, in particular, a substantial deviation from spherical symmetry. In this connection, we further elaborate on relevant aspects of oscillations ($ε^2$ corrections, adiabaticity violation, entanglement, {\it etc.}) and the attenuation effect. The night excesses of the $νe-$ and $νN-$ events and the Day-Night asymmetries, $A_{ND}$, are presented in terms of the matter potential and the generalized energy resolution functions. The energy dependences of the cross-section and the flux improve the resolution, and consequently, sensitivity to remote structures of the profiles. The nadir angle ($η$) dependences of $A_{ND}$ are computed for future detectors DUNE, THEIA, Hyper-Kamiokande, and MICA at the South pole. Perspectives of the oscillation tomography of the Earth with the boron neutrinos are discussed. Next-generation detectors will establish the integrated day-night asymmetry with high confidence level. They can give some indications of the $η-$ dependence of the effect, but will discriminate among different models at most at the $(1 - 2)σ$ level. For high-level discrimination, the MICA-scale experiments are needed. MICA can detect the ice-soil borders and perform unique tomography of Antarctica.

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arXiv2020

Sensitivities of future solar neutrino observatories to NSI

We study the matter effect caused by non-standard neutrino interactions (NSI) in the future solar neutrino experiments, DUNE, HK and MICA. The upcoming reactor experiment, JUNO is expected to provide the most precise measurements of solar neutrino oscillation parameters and is going to open up the era of sub-percent precision in the leptonic mixing sector of the Standard Model (SM). Considering JUNO can measure $Δm ^2 _{21}$ and $θ_{12}$ by sub-percent precision and assuming SM as the null hypothesis, we study the possibility to constrain NSI parameters by the future solar neutrino experiments such as DUNE, HK and MICA. For this purpose, we study the effect of NSI on solar neutrino propagation in the Sun and Earth and explore the dependence of the day-night asymmetry on the NSI parameters. We also study the effect of NSI at the water Cerenkov detector on the simulated data for these experiments.

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arXiv2019

Secret interactions of neutrinos with light gauge boson at the DUNE near detector

Secret interactions of neutrinos with light new gauge bosons, $Z^\prime$, can lead to a rich phenomenology in supernova explosion as well as in the early Universe. This interaction can also lead to new decay modes for charged mesons, $π^+ (K^+) \to e^+ νZ'$, and subsequently to $Z'\to ν\barν$. After demonstrating that such an interaction can be accommodated within viable electroweak symmetric models, we study how the near detector (ND) of DUNE can probe this scenario. We also discuss how the DUNE ND can make it possible to reconstruct the flavor structure of the $Z^\prime$ coupling to neutrinos.

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arXiv2017

Sensitivities to charged-current nonstandard neutrino interactions at DUNE

We investigate the effects of charged-current (CC) nonstandard neutrino interactions (NSIs) at the source and at the detector in the simulated data for the planned Deep Underground Neutrino Experiment (DUNE), while neglecting the neutral-current NSIs at the propagation due to the fact that several solutions have been proposed to resolve the degeneracies posed by neutral-current NSIs while no solution exists for the degeneracies due to the CC NSIs. We study the effects of CC NSIs on the simultaneous measurements of $θ_{23}$ and $δ_{CP}$ in DUNE. The analysis reveals that 3$σ$ C.L. measurement of the correct octant of $θ_{23}$ in the standard mixing scenario is spoiled if the CC NSIs are taken into account. Likewise, the CC NSIs can deteriorate the uncertainty of the $δ_{CP}$ measurement by a factor of two relative to that in the standard oscillation scenario. We also show that the source and the detector CC NSIs can induce a significant amount of fake CP-violation and the CP-conserving case can be excluded by more than 80\% C.L. in the presence of fake CP-violation. We further find the potential of DUNE to constrain the relevant CC NSI parameters from the single parameter fits for both neutrino and antineutrino appearance and disappearance channels at both the near and far detectors. The results show that there could be improvement in the current bounds by at least one order of magnitude at the near and far detector of DUNE except a few parameters which remain weaker at the far detector.

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arXiv2017

Constraining secret gauge interactions of neutrinos by meson decays

Secret coupling of neutrinos to a new light vector boson, $Z'$, with a mass smaller than 100 MeV is motivated within a myriad of scenarios which are designed to explain various anomalies in particle physics and cosmology. Due to the longitudinal component of the massive vector boson, the rates of three-body decay of charged mesons ($M$) such as the pion and the kaon to the light lepton plus neutrino and $Z'$ ($M \to l νZ'$) are enhanced by a factor of $(m_M/m_{Z'})^2$. On the other hand, the standard two body decay $M \to l ν$ is suppressed by a factor of $(m_l/m_M)^2$ due to chirality. We show that in the case of ($M \to e νZ^\prime$), the enhancement of $m_M^4/m_e^2 m_{Z^\prime}^2\sim 10^8-10^{10}$ relative to two-body decay ($M \to e ν$) enables us to probe very small values of gauge coupling for $ν_e$. The strongest bound comes from the $R_K\equiv Br(K \to e +ν)/Br(K \to μ+ν)$ measurement in the NA62 experiment. The bound can be significantly improved by customized searches for signals of three-body charged meson decay into the positron plus missing energy in the NA62 and/or PIENU data.

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arXiv2016

CP-Violation and Non-Standard Interactions at the MOMENT

To measure the last unknown $3ν$ oscillation parameter ($δ$), several long baseline neutrino experiments have been designed or proposed. Recently it has been shown that turning on neutral current Non-Standard Interactions (NSI) of neutrinos with matter can induce degeneracies that may even hinder the proposed state-of-the-art DUNE long baseline experiment from measuring the value of $δ$. We study how the result of the proposed MOMENT experiment with a baseline of 150 km and $200~{\rm MeV}<E_ν<600~{\rm MeV}$ can help to solve the degeneracy induced by NSI and determine the true value of $δ$.

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