Sterile neutrinos with mass in the eV-scale and large mixings of order $θ_0\simeq 0.1$ could explain some anomalies found in short-baseline neutrino oscillation data. Here, we revisit a neutrino portal scenario in which eV-scale sterile neutrinos have self-interactions via a new gauge vector boson $ϕ$. Their production in the early Universe via mixing with active neutrinos can be suppressed by the induced effective potential in the sterile sector. We study how different cosmological observations can constrain this model, in terms of the mass of the new gauge boson, $M_ϕ$, and its coupling to sterile neutrinos, $g_s$. Then, we explore how to probe part of the allowed parameter space of this particular model with future observations of the diffuse supernova neutrino background by the Hyper-Kamiokande and DUNE detectors. For $M_ϕ\sim 5-10$~keV and $g_s \sim 10^{-4}-10^{-2}$, as allowed by cosmological constraints, we find that interactions of diffuse supernova neutrinos with relic sterile neutrinos on their way to the Earth would result in significant dips in the neutrino spectrum which would produce unique features in the event spectra observed in these detectors.
We consider the effects of active-sterile secret neutrino interactions, mediated by a new pseudoscalar particle, on high- and ultra high-energy neutrino fluxes. In particular, we focus on the case of 3 active and 1 sterile neutrino coupled by a flavor dependent interaction, extending the case of 1 active and 1 sterile neutrino we have recently examined. We find that, depending on the kind of interaction of sterile neutrino with the active sector, new regions of the parameter space for secret interactions are now allowed leading to interesting phenomenological implications on two benchmark flux…
While three flavors of "active" neutrinos are consistent with mixing angle results within error bars, there are anomalies may be hints of physics beyond the standard model that can accommodate a fourth mostly "sterile" neutrino species with an eV-scale mass and a mixing angle with active neutrinos of order $θ_0\simeq 0.1$. We describe a scenario with eV-scale sterile neutrinos that have self-interactions via a new gauge vector boson, a "secret" mediator $ϕ$. We show that their production in the early Universe via mixing with active neutrinos is consistent with Big Bang Nucleosynthesis and free…
keV scale sterile neutrinos are excellent warm dark matter candidates. In the early Universe, these can be produced from oscillations and scatterings of active neutrinos. However, in the absence of any new physics, this mechanism is in severe tension with observations from X-ray searches. In this work, we show that secret self-interactions of active neutrinos, mediated by a scalar, can efficiently produce these sterile neutrinos without being ruled out by X-ray observations. These neutrino self-interactions are also testable: for a mediator mass greater than a few MeV, these self-interactions …
Secret neutrino interactions can play an essential role in the origin of dark matter. We present an anatomy of production mechanisms for sterile neutrino dark matter, a keV-scale gauge-singlet fermion that mixes with active neutrinos, in the presence of a new vector boson mediating secret interactions among active neutrinos. We identify three regimes of the vector boson's mass and coupling where it makes distinct impact on dark matter production through the dispersion relations and/or scattering rates. We also analyze models with gauged $L_μ-L_τ$ and $B-L$ numbers which have a similar dark mat…
Unveiling secret interactions among sterile neutrinos with big-bang nucleosynthesis
短基线中微子异常表明存在低质量（m \sim O（1）~eV）的无菌中微子ν_s。在早期宇宙中，这些粒子会通过活跃中微子的振荡而有效地产生，导致无菌态的热布居，这似乎与宇宙学观测不相容。为了缓解这种紧张关系，最近有人推测，由大质量规范玻色子X（M_X << M_W）介导的不育中微子之间的新的“秘密”相互作用，由于产生大的物质势项，可以抑制或抑制不育中微子热化。然而，我们注意到，它们也在无菌中微子部分产生强碰撞项，在遇到物质共振后诱导有效的无菌中微子产生，增加它们对相对论粒子种类N_ eff数量的贡献。此外，在温度T \lesssim几MeV处发生共振的ν_s-ν_s相互作用的参数值，在电子（反）中微子谱中产生显著的畸变，改变了大爆炸核合成（BBN）中轻元素的丰度。使用本确定的$^4$他和氘原始丰度，我们确定的BBN约束的模型参数。我们发现，如果假设重子密度为普朗克实验的最佳拟合值Ω_B h ^2 = 0.02207，则$^2$ H/H密度比排除了大部分的参数空间，而当Ω_B h ^2 =0.02261时（95% C. L. Planck的上界由于实验测定的误差较大，氦的质量分数Y_p没有给出明显的界限。
Neutrinos offer a window to physics beyond the Standard Model. In particular, high-energy astrophysical neutrinos, with TeV-PeV energies, may provide evidence of new, "secret" neutrino-neutrino interactions that are stronger than ordinary weak interactions. During their propagation over cosmological distances, high-energy neutrinos could interact with the cosmic neutrino background via secret interactions, developing characteristic energy-dependent features in their observed energy distribution. For the first time, we look for signatures of secret neutrino interactions in the diffuse flux of h…
The MiniBooNE experiment has observed a significant excess of electron neutrinos in a muon neutrino beam at source-detector distances too short to be compatible with standard neutrino oscillations. The most straightforward explanation for this signal in terms of oscillations between Standard Model neutrinos and a new, sterile, neutrino, is disfavored by null results from experiments looking for muon neutrino disappearance. Here, we discuss the possibility that MiniBooNE data are instead explained by a sterile neutrino that decays quickly back into active neutrinos plus a light boson. The flavo…
We present two complementary NuSTAR x-ray searches for keV-scale dark matter decaying to mono-energetic photons in the Milky Way halo. In the first, we utilize the known intensity pattern of unfocused stray light across the detector planes -- the dominant source of photons from diffuse sources -- to separate astrophysical emission from internal instrument backgrounds using ${\sim}$7-Ms/detector deep blank-sky exposures. In the second, we present an updated parametric model of the full NuSTAR instrument background, allowing us to leverage the statistical power of an independent ${\sim}$20-Ms/de…
Dark matter might be made of "warm" particles, such as sterile neutrinos in the keV mass range, which can decay into photons through mixing and are consequently detectable by X-ray telescopes. Axionlike particles (ALPs) are detectable by X-ray telescopes too when coupled to standard model particles and decay into photons in the keV range. Both particles could explain the unidentified 3.5 keV line and, interestingly, XENON1T observed an excess of electron recoil events most prominent at 2-3 keV. One explanation could be an ALPs origin, which is not yet excluded by X-ray constraints in an anomal…
Several neutrino experiments have reported results that are potentially inconsistent with our current understanding of the lepton sector. A candidate solution to these so-called short-baseline anomalies is postulating the existence of new, eV-scale, mostly sterile neutrinos that mix with the active neutrinos. This hypothesis, however, is strongly disfavored once one considers all neutrino data, especially those that constrain the disappearance of muon and electron neutrinos at short-baselines. Here, we show that if the sterile-active mixing parameters depend on the energy-scales that character…
Neutrinos might interact among themselves through forces that have so far remained hidden. Throughout the history of the Universe, such \emph{secret} interactions could lead to scatterings between the neutrinos from supernova explosions and the non-relativistic relic neutrinos left over from the Big Bang. Such scatterings can boost the cosmic neutrino background (C$ν$B) to energies of ${\cal O}$(MeV), making it, in principle, observable in experiments searching for the diffuse supernova neutrino background. Assuming a model-independent, but flavor universal, four-Fermi interaction, we determin…
The potential of diffuse Galactic Ridge neutrino measurements to constrain dark matter
Instituto de Fisica Teorica UAM-CSIC, Universidad Autonoma de Madrid（马德里自治大学理论物理研究所）；Departamento de Fisica Teorica, M-15, Universidad Autonoma de Madrid（马德里自治大学理论物理系）；Department of Information Technology, Escuela Politécnica Superior, Universidad San Pablo-CEU（圣巴勃罗ceu大学高等理工学院信息技术系）
A Search for a keV Signature of Radiatively Decaying Dark Matter with Suzaku XIS Observations of the X-ray Diffuse Background
我们用朱雀XIS对来自非重子暗物质的0.5至7 keV之间的X射线发射线进行了最深的搜索。选择与银河系有关的暗物质作为目标，以获得最佳的信噪比。我们从朱雀天文台的资料库中选取了187组以X射线散射背景为主的空白天空区域的数据。数据集是从2005年到2013年。仪器的响应是由蟹状星云的多个校准数据集调整的。我们还改进了减去仪器源谱线的技术。这些能谱可以用太阳系周围电荷交换产生的X射线辐射、银河系内部和周围的热等离子体以及河外点源的叠加来描述。搜索窄发射谱线的信号，并且考虑盲搜索方法（别处寻找效应）来评价检测的显著性。我们的研究结果显示，没有显着的检测到发射线功能的暗物质。3 $σ$的上限为1至7 keV之间的发射线强度的$\sim10^{-2}$光子cm $^{-2}$ s $^{-1}$ sr $^{-1}$，或$\sim 5\times10^{-4}$光子cm $^{-2}$ s $^{-1}$ sr $^{-1}$ per $M_\odot$ pc $^{-2}$，假设暗物质分布与银河系旋转曲线。作为暗物质候选者的无菌中微子的参数也受到限制。
LHAASO collaboration detected photons with energy above 10 TeV from the most recent gamma-ray burst (GRB), GRB221009A. Given the redshift of this event, $z\sim 0.15$, photons of such energy are expected to interact with the diffuse extragalactic background light (EBL) well before reaching Earth. In this paper we provide a novel neutrino-related explanation of the most energetic 18 TeV event reported by LHAASO. We find that the minimal viable scenario involves both mixing and transition magnetic moment portal between light and sterile neutrinos. The production of sterile neutrinos occurs effici…
Probing Scalar Non-Standard Neutrino Interactions using High-Energy Astrophysical Neutrinos
University of South Dakota（南达科他大学）；Harvard University（哈佛大学）；Washington University, St. Louis（华盛顿大学（圣路易斯））；Johannes Gutenberg-Universität Mainz（美因茨约翰内斯古腾堡大学）；Durham University（杜伦大学）
