Invisible Decay Research Articles

Electrolyte Reconfiguration by Cation/Anion Cross‐coordination for Highly Reversible and Facile Sodium Storage

Hard carbon (HC) materials are promising anodes for sodium‐ion batteries (SIBs) owing to low cost, high specific capacity and low working potential. However, the poor compatibility of the electrolyte with HC leads to low initial coulombic efficiency (ICE) and sluggish Na+ transport kinetics. Here, we propose an electrolyte reconfiguration strategy based on the hard and soft acid and base (HSAB) theory by introducing methyltriphenylphosphonium bromide (MTPPB). MTPPB can realize a spontaneous cross‐coordination solvation structure with NaPF6 by selective affinity, synchronously optimizing the interfacial chemistry and sodium storage process. The advantages of the chemical π‐π bridging of MTPP+‐HC and interaction of MTPP+‐PF6− contribute to preferential and oriented reduction of PF6−, forming a low‐resistance supramolecular SEI. Additionally, Na+‐Br− coordination weakens the Na+‐solvent interactions, facilitating Na+ de‐solvation kinetics. Consequently, the HC||Na cell achieves a superior ICE of 96.6%, desirable rate capability under 25 °C and invisible capacity decay after 500 cycles at 1 C under −20 °C. The Na4Fe3(PO4)2P2O7||HC pouch battery displays a high ICE of 90.3% and a 15% increment of energy density under 25 °C. This work provides a guidance through electrolyte reconfiguration engineering for designing practical HC‐based SIBs with high energy/power density and long‐life span in the extended operating‐temperature range.

Electrolyte Reconfiguration by Cation/Anion Cross-coordination for Highly Reversible and Facile Sodium Storage.

Hard carbon (HC) materials are promising anodes for sodium-ion batteries (SIBs) owing to low cost, high specific capacity and low working potential. However, the poor compatibility of the electrolyte with HC leads to low initial coulombic efficiency (ICE) and sluggish Na+ transport kinetics. Here, we propose an electrolyte reconfiguration strategy based on the hard and soft acid and base (HSAB) theory by introducing methyltriphenylphosphonium bromide (MTPPB). MTPPB can realize a spontaneous cross-coordination solvation structure with NaPF6 by selective affinity, synchronously optimizing the interfacial chemistry and sodium storage process. The advantages of the chemical π-π bridging of MTPP+-HC and interaction of MTPP+-PF6- contribute to preferential and oriented reduction of PF6-, forming a low-resistance supramolecular SEI. Additionally, Na+-Br- coordination weakens the Na+-solvent interactions, facilitating Na+ de-solvation kinetics. Consequently, the HC||Na cell achieves a superior ICE of 96.6%, desirable rate capability under 25 °C and invisible capacity decay after 500 cycles at 1 C under -20 °C. The Na4Fe3(PO4)2P2O7||HC pouch battery displays a high ICE of 90.3% and a 15% increment of energy density under 25 °C. This work provides a guidance through electrolyte reconfiguration engineering for designing practical HC-based SIBs with high energy/power density and long-life span in the extended operating-temperature range.

Dark-Sector Search via Pion-Produced η and η^{'} Mesons Decaying Invisibly in the NA64h Detector.

We present the first results from a proof-of-concept search for dark sectors via invisible decays of pseudoscalar η and η^{'} mesons in the NA64h experiment at the CERN SPS. Our novel technique uses the charge-exchange reaction of 50GeV π^{-} on nuclei of an active target as the source of neutral mesons. The η,η^{'}→invisible events would exhibit themselves via a striking signature-the complete disappearance of the incoming beam energy in the detector. No evidence for such events has been found with 2.9×10^{9} pions on target accumulated during one day of data taking. This allows us to set a stringent limit on the branching ratio Br(η^{'}→invisible)<2.1×10^{-4} improving the current bound by a factor of ≃3. We also set a limit on Br(η→invisible)<1.1×10^{-4} comparable with the existing one. These results demonstrate the great potential of our approach and provide clear guidance on how to enhance and extend the sensitivity for dark sector physics from future searches for invisible neutral meson decays.

Synergy between DUNE and T2HKK to probe invisible neutrino decay

We address the consequence of invisible neutrino decay within the framework of two long base-line neutrino experiments: T2HKK (Tokai-to-Hyper-Kamiokande-to-Korea) and DUNE (Deep Underground Neutrino experiment). Our primary objective is to bring out the aspects of CC (charged current) and NC (neutral current) measurements at DUNE in the context of invisible neutrino decay. We find that the inclusion of NC measurements with the CC measurements enhances its ability to constrain invisible neutrino decay. Further, the synergy between DUNE and T2HKK improves the constraints on invisible neutrino decay. At 3σ C.L. (confidence level) the derived constraint is τ3/m3 ≥ 6.21 × 10−11 s/eV. Additionally, if nature prefers ν3 to be unstable and the decay width is τ3/m3 = 2.2 × 10−11 s/eV, this combination can exclude the no-decay scenario at more than 5σ C.L. Although the CP sensitivity is not much hindered in the presence of invisible neutrino decay, the measurements of θ23 and the ability to resolve octant of θ23 is significantly influenced in these individual experiments. In the presence of invisible neutrino decay, the synergy between DUNE and T2HKK can exclude the wrong octant somewhat more effectively than either experiment alone.

Helicity-changing decays of cosmological relic neutrinos

In this paper, we examine the possibility that massive neutrinos are unstable due to their invisible decays ν i → ν j + ϕ, where ν i and ν j (for i, j = 1, 2, 3) are any two of neutrino mass eigenstates with masses m i > m i and ϕ is a massless Nambu-Goldstone boson, and explore the implications for the detection of cosmological relic neutrinos in the present Universe. First, we carry out a complete calculation of neutrino decay rates in the general case where the individual helicities of parent and daughter neutrinos are specified. Then, the invisible decays of cosmological relic neutrinos are studied and their impact on the capture rates on the beta-decaying nuclei (e.g., ν e + 3H → 3He + e -) is analyzed. The invisible decays of massive neutrinos could substantially change the capture rates in the PTOLEMY-like experiments when compared to the case of stable neutrinos. In particular, we find that the helicity-changing decays of Dirac neutrinos play an important role whereas those of Majorana neutrinos have no practical effects. However, if a substantial fraction of heavier neutrinos decay into the lightest one, the detection of relic neutrinos will require a much higher energy resolution and thus be even more challenging.

Baryon-number-violating nucleon decays in ALP effective field theories

The search for baryon-number-violating (BNV) nucleon decay is an intriguing probe of new physics beyond the SM in future neutrino experiments with enhanced sensitivity. The dark sector states such as an axion or axion-like particle (ALP) can induce nucleon decays with distinct signature and kinematics from the conventional nucleon decays. In this work, we study the ALP effective field theories (EFTs) with baryon number violation and the impact of light ALP on BNV nucleon decays. We revisit the dimension-8 BNV operators in the extended EFTs with an ALP field a respecting shift symmetry. The low-energy EFT operators with |∆(B – L)| = 2 and |∆(B – L)| = 0 are matched to the baryon chiral perturbation theory. We obtain the effective chiral Lagrangian and the BNV interactions between ALP and baryons/mesons. The ALP interactions lead to two-body baryon decays B → ℓ (or ν) a and three-body nucleon decays N → M ℓ (or ν) a. We obtain the constraints on the UV scale from the invisible Λ0 decay search at BESIII, the invisible neutron decay search at KamLAND and proton decay search at Super-K. We also show the projections of some other baryon/nucleon decays and present the distinct distributions of kinematic observable.

Stau pairs from natural SUSY at high luminosity LHC

Natural supersymmetry (SUSY) with light Higgsinos is perhaps the most plausible of all weak scale SUSY models while a variety of motivations point to (right) tau sleptons as the lightest of all the sleptons. We examine a SUSY model line with rather light right staus embedded within natural SUSY. For light τ˜1 of a few hundred GeV, the decays τ˜1→τχ˜1,20 and ντχ˜1− occur at comparable rates where the (Higgsino-like) χ˜1± and χ˜20 release only small visible energy: in this case, the expected τ+τ−+ET signature is diminished from the usual expectations due to the presence of the nearly invisible decay mode τ˜1→ντχ˜1−. However, once mτ˜1≳m(bino), decays to binos such as τ˜1→τχ˜30 open up where χ˜30 decays to Higgsinos plus W±, Z0, and h at comparable rates. For these heavier staus, the stau pair production gives rise to diboson+ET events, which may contain 0, 1, or 2 additional hard τ leptons. From these considerations, we examine the potential for future discovery of tau-slepton pair production at a high-luminosity LHC. While we do not find a 5σ HL-LHC discovery reach for 3000 fb−1, we do find a 95% CL exclusion reach, ranging between mτ˜1: 100–450 GeV for mχ˜10∼100 GeV. This latter reach disappears for mχ˜10≳200 GeV. Published by the American Physical Society 2024

Higgs portal dark matter freeze-in at stronger coupling: observational benchmarks

We study freeze-in production of Higgs portal dark matter (DM) at temperatures far below the dark matter mass. The temperature of the Standard Model (SM) thermal bath may have never been high such that dark matter production via thermal emission has been Boltzmann-suppressed. This allows for a significant coupling between the Higgs field and DM, which is being probed by the direct DM detection experiments and invisible Higgs decay searches at the LHC. We delineate the corresponding parameter space in the Higgs portal framework with dark matter of spin 0, 1/2 and 1.

Limits on non-relativistic matter during Big-bang nucleosynthesis

Big-bang nucleosynthesis (BBN) probes the cosmic mass-energy density at temperatures ∼ 10 MeV to ∼ 100 keV. Here, we consider the effect of a cosmic matter-like species that is non-relativistic and pressureless during BBN. Such a component must decay; doing so during BBN can alter the baryon-to-photon ratio, η, and the effective number of neutrino species. We use light element abundances and the cosmic microwave background (CMB) constraints on η and Nν to place constraints on such a matter component. We find that electromagnetic decays heat the photons relative to neutrinos, and thus dilute the effective number of relativistic species to N eff < 3 for the case of three Standard Model neutrino species. Intriguingly, likelihood results based on Planck CMB data alone find Nν = 2.800 ± 0.294, and when combined with standard BBN and the observations of D and 4He give Nν = 2.898 ± 0.141. While both results are consistent with the Standard Model, we find that a nonzero abundance of electromagnetically decaying matter gives a better fit to these results. Our best-fit results are for a matter species that decays entirely electromagnetically with a lifetime τX = 0.89 sec and pre-decay density that is a fraction ξ = (ρX /ρ rad|10 MeV = 0.0026 of the radiation energy density at 10 MeV; similarly good fits are found over a range where ξτX 1/2 is constant. On the other hand, decaying matter often spoils the BBN+CMB concordance, and we present limits in the (τX ,ξ) plane for both electromagnetic and invisible decays. For dark (invisible) decays, standard BBN (i.e. ξ = 0) supplies the best fit. We end with a brief discussion of the impact of future measurements including CMB-S4.

The first limit on invisible decays of Bs\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_s$$\\end{document} mesons comes from LEP

Motivated by the recent evidence for B+→K+ν¯ν\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B^+\\rightarrow K^+\\bar{\ u } \ u $$\\end{document} decays at Belle II, we point out that fully invisible Bd\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_d$$\\end{document} and Bs\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_s$$\\end{document} meson decays are strongly constrained by LEP. A reinterpretation of an old inclusive ALEPH search for b-hadron decays with large missing energy allows us to place the limits Br(Bd→invisible)<1.4×10-4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{Br}(B_d \\rightarrow \ extrm{invisible}) < 1.4\ imes 10^{-4}$$\\end{document} and Br(Bs→invisible)<5.6×10-4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{Br}(B_s \\rightarrow \ extrm{invisible}) < 5.6\ imes 10^{-4}$$\\end{document}, both at 90%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$90\\%$$\\end{document} CL. The Bd\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_d$$\\end{document} limit is only a factor of 6 looser than the world-leading one provided by the BaBar collaboration, while the Bs\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$B_s$$\\end{document} one is the first limit in the literature on this decay mode. These results are relevant in the context of new light states coupled to quarks and exemplify the power of a future Tera-Z factory at FCC-ee to look for B meson decays containing missing energy.

The quark flavor-violating ALPs in light of B mesons and hadron colliders

The axion-like particle (ALP) may induce flavor-changing neutral currents (FCNCs) when the fermions’ Peccei-Quinn charges are not generation universal. The search for flavor-violating ALP couplings with a bottom quark so far focused on FCNC processes of B mesons at low energies. The recent measurements of B → K + X rare decays place stringent bounds on the quark flavor violations of a light ALP in different decay modes. In this work we propose a novel direct search for bottom flavor-violating interaction of a heavy ALP at the LHC and its upgrades, namely QCD production of an ALP associated with one b jet and one light jet p p → b j a. We consider the decay of the ALP to photons, muons and invisible ALP decays. The Boosted Decision Tree (BDT) algorithm is used to analyze the events and we train the BDT classifier by feeding in the kinematic observables of signal and backgrounds. Finally, we show the complementarity between the search prospects of hadron colliders and the low-energy B meson constraints from B meson mixing and B meson decays to a light ALP.

Invisible and semi-invisible decays of bottom baryons* *The work is partly Supported by the National Key Research and Development Program of China (2020YFA0406400, 2023YFA1606000), and the National Natural Science Foundation of China (12335003, 12275277)

The similar densities of dark matter and baryons in the universe imply that they may arise from the same ultraviolet model. B-Mesogenesis, which assumes dark matter is charged under the baryon number, attempts to simultaneously explain the origin of baryon asymmetry and dark matter in the universe. In particular, B-Mesogenesis may induce bottom-baryon decays into invisible or semi-invisible final states, which provide a distinctive signal for probing this scenario. In this work, we systematically study the invisible decays of bottom baryons into dark matter and the semi-invisible decays of bottom baryons into a meson or a photon together with a dark matter particle. In particular, the fully invisible decay can reveal the stable particles in B-Mesogenesis. Some QCD-based frameworks are used to calculate the hadronic matrix elements under the B-Mesogenesis model. We estimate the constraints on the Wilson coefficients or the product of some new physics couplings with the Wilson coefficients according to the semi-invisible and invisible decays of bottom baryons detectable at future colliders.

The Sun and core-collapse supernovae are leading probes of the neutrino lifetime

The large distances travelled by neutrinos emitted from the Sun and core-collapse supernovae together with the characteristic energy of such neutrinos provide ideal conditions to probe their lifetime, when the decay products evade detection. We investigate the prospects of probing invisible neutrino decay capitalising on the detection of solar and supernova neutrinos as well as the diffuse supernova neutrino background (DSNB) in the next-generation neutrino observatories Hyper-Kamiokande, DUNE, JUNO, DARWIN, and RES-NOVA.We find that future solar neutrino data will be sensitive to values of the lifetime-to-mass ratio τ 1/m 1 and τ 2/m 2 of 𝒪(10-1–10-2) s/eV. From a core-collapse supernova explosion at 10 kpc, lifetime-to-mass ratios of the three mass eigenstates of 𝒪(105) s/eV could be tested. After 20 years of data taking, the DSNB would extend the sensitivity reach of τ 1/m 1 to 108 s/eV. These results promise an improvement of about 6–15 orders of magnitude on the values of the decay parameters with respect to existing limits.

Heavy neutral lepton corrections to SM boson decays: lepton flavour universality violation in low-scale seesaw realisations

We study lepton flavour universality violation in SM boson decays in low-scale seesaw models of neutrino mass generation, also addressing other electroweak precision observables. We compute the electroweak next-to-leading order corrections, which turn out to be important – notably in the case of the invisible decay width of the Z boson, for which the corrections can be as large as the current experimental uncertainty. As a well-motivated illustrative study case, we choose a realisation of the Inverse Seesaw mechanism, and discuss the complementary role of lepton flavour conserving, lepton flavour violating and precision observables, both in constraining and in probing such models of neutrino mass generation. Our findings suggest that invisible Z decays are especially important, potentially at the origin of the most stringent constraints for certain regimes of the Inverse Seesaw (while complying with charge lepton flavour violation and other electroweak precision tests). We also discuss the probing power of the considered observables in view of the expected improvement in experimental precision at FCC-ee.

Multicomponent scalar dark matter with an extended Gauge sector

We consider an extension of the Standard Model of particle physics with an additional SU(2) gauge sector along with an additional scalar bidoublet and a non-linear sigma field. The neutral components of the bidoublet serve as dark matter candidates by virtue of the bidoublet being odd under a Z2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Z_2$$\\end{document} symmetry. Generic beyond Standard Model constraints like vacuum stability, invisible decay of Higgs, Higgs alignment limit and collider constraints on heavy gauge bosons restrict the parameter space of this model. In this multicomponent dark matter scenario, we investigate the interplay between the annihilation and co-annihilation channels originating from the new gauge sector as those contribute to the relic abundance. We also inspect the direct detection constraints on scattering cross-sections of the dark matter particles with the detector nucleons and present our observations.

Precision Higgs width and couplings with a high energy muon collider

The interpretation of Higgs data is typically based on different assumptions about whether there can be additional decay modes of the Higgs or if any couplings can be bounded by theoretical arguments. Going beyond these assumptions requires either a precision measurement of the Higgs width or an absolute measurement of a coupling to eliminate a flat direction in precision fits that occurs when ghVV/ghVVSM\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\left|{g}_{hVV}/{g}_{hVV}^{SM}\\right| $$\\end{document} > 1, where V = W±, Z. In this paper we explore how well a high energy muon collider can test Higgs physics without having to make assumptions on the total width of the Higgs. In particular, we investigate off-shell methods for Higgs production used at the LHC and searches for invisible decays of the Higgs to see how powerful they are at a muon collider. We then investigate the theoretical requirements on a model which can exist in such a flat direction. Combining expected Higgs precision with other constraints, the most dangerous flat direction is described by generalized Georgi-Machacek models. We find that by combining direct searches with Higgs precision, a high energy muon collider can robustly test single Higgs precision down to the O.1%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{O}\\left(.1\\%\\right) $$\\end{document} level without having to assume SM Higgs decays. Furthermore, it allows one to bound new contributions to the width at the sub-percent level as well. Finally, we comment on how even in this difficult flat direction for Higgs precision, a muon collider can robustly test or discover new physics in multiple ways. Expanding beyond simple coupling modifiers/EFTs, there is a large region of parameter space that muon colliders can explore for EWSB that is not probed with only standard Higgs precision observables.

Global analysis of the ALP effective theory

We perform a global fit of the effective Lagrangian for axion-like particles (ALPs) to data. By combining LHC observables from top physics, dijet and di-boson production with electroweak precision observables, we resolve the full parameter space of ALPs with flavor-universal couplings. Using the renormalization group to evolve the effective ALP couplings to low energies allows us to investigate the impact of flavor observables on the global analysis. We show that resonance searches in B → K meson decays significantly enhance the sensitivity to ALPs with sub-GeV masses. The lifetime of the ALP plays a crucial role in resolving the multi-dimensional parameter space with searches for prompt, displaced and invisible ALP decays. Our analysis points out the differences in probing an effective theory with new light particles, compared to scenarios with only non-resonant effects of heavy particles at low energies, as in the Standard Model Effective Field Theory.

NNLO QCD predictions of the asymmetry probe of the Z γ pair-production process

The paper presents for the first time a novel idea of exploiting asymmetry between differential cross sections of the off-shell Z γ pair-production in proton-proton (pp) collisions for the final states of a charged-lepton pair plus a photon pp → Z γ → l + l − γ (leptonic decay) and of a neutrino pair plus a photon (invisible decay). Asymmetry between the leptonic and invisible decays of the Z γ process is investigated by using fixed-order predictions through inclusion of next-to-next-to-leading (NNLO) radiative corrections in quantum chromodynamics (QCD) perturbation theory. NNLO QCD predictions are presented at various pp-collision energies as functions of several key observables including transverse momenta and azimuthal-angle separation, regarding the Z γ decay products. The predicted distributions for the Z γ asymmetry are provided based on realistic fiducial phase-space requirements in line with the related hadron-collider measurements. The predicted distributions are assessed at various pp-collision energies and in different phase-space regions such as with higher lepton-pair invariant mass or higher neutrino-pair transverse momentum requirements. The Z γ asymmetry is shown to be significantly sensitive in different regions of phase space including high- and high- regions. The Z γ asymmetry can therefore be translated into an important quantity for probing deviation from the Standard Model (SM) predictions. In this regard, the asymmetry probe is proposed as a sensitive indicator for indirect searches for physics beyond the SM encompassing high-mass resonances and dark-matter sector.

Probing invisible vector meson decay mode with the hadronic beam in the NA64 experiment at SPS CERN

Probing invisible vector meson decay mode with the hadronic beam in the NA64 experiment at SPS CERN

Search for Boosted Dark Matter in COSINE-100.

We search for energetic electron recoil signals induced by boosted dark matter (BDM) from the galactic center using the COSINE-100 array of NaI(Tl) crystal detectors at the Yangyang Underground Laboratory. The signal would be an excess of events with energies above 4MeV over the well-understood background. Because no excess of events are observed in a 97.7 kg·yr exposure, we set limits on BDM interactions under a variety of hypotheses. Notably, we explored the dark photon parameter space, leading to competitive limits compared to direct dark photon search experiments, particularly for dark photon masses below 4MeV and considering the invisible decay mode. Furthermore, by comparing our results with a previous BDM search conducted by the Super-Kamionkande experiment, we found that the COSINE-100 detector has advantages in searching for low-mass dark matter. This analysis demonstrates the potential of the COSINE-100 detector to search for MeV electron recoil signals produced by the dark sector particle interactions.