KOTO和NA 62这两个K介子工厂位于强度前沿的最前沿，测量和分析了前所未有的长寿命和带电K介子数量，约为10^{13}。这些实验目前有一个独特的机会来寻找暗区。在本文中，我们证明了在KOTO和NA 62进行的搜索是互补的，都是探索未知的领域。我们考虑两种性质不同的物理情况。首先，我们分析了耦合到胶子或电弱规范玻色子的类轴子粒子（ALP）模型。在第二，我们介绍了一个模型的基础上近似奇怪的味道对称性，导致一个强烈的违反Grossman-Nir界。对于第一种情况，我们为KOTO实验设计了一个新的搜索策略，K_L -> pi^0 a -> 4 gamma。其对分支比的预期灵敏度在10^{-9}的水平。这证明了KOTO作为发现机器的巨大潜力。此外，我们重新审视其他界限的ALP从K介子工厂，突出的主要来源的理论不确定性，对撞机实验，并显示新的预测。对于第二种情况，我们表明，该模型可能是兼容的KOTO数据的初步分析，显示新物理学的提示。
英文摘要：
The two kaon factories, KOTO and NA62, are at the cutting edge of the intensity frontier, with an unprecedented numbers of long lived and charged Kaons, ~ 10^{13}, being measured and analyzed. These experiments have currently a unique opportunity to search for dark sectors. In this paper, we demonstrate that searches done at KOTO and NA62 are complementary, both probing uncharted territories. We consider two qualitatively different physics cases. In the first, we analyze models of axion-like-particles (ALP) which couple to gluons or electroweak gauge bosons. In the second, we introduce a model based on an approximate strange flavor symmetry that leads to a strong violation of the Grossman-Nir bound. For the first scenario, we design a new search strategy for the KOTO experiment, K_L -> pi^0 a -> 4 gamma . Its expected sensitivity on the branching ratio is at the level of 10^{-9}. This demonstrates the great potential of KOTO as a discovery machine. In addition, we revisit other bounds on ALPs from Kaon factories, highlighting the main sources of theoretical uncertainty, and collider experiments, and show new projections. For the second scenario, we show that the model may be compatible with the preliminary analysis of the KOTO-data that shows a hint for New Physics.
We present a dark sector model that reproduces the KOTO, MiniBooNE and muon anomalous magnetic moment anomalies. The dark sector is comprised of a light scalar singlet $S$ that has a large coupling to a slightly heavier sterile neutrino that mixes with the active neutrinos. The scalar couples to standard model fermions via Yukawa couplings, and to photons via a higher-dimensional coupling. The KOTO signal is a result of the flavor-changing penguin process $K_L \to π^0 S$ followed by the decay of $S$ to neutrinos. The sterile neutrino produced in neutrino-nucleus scattering at MiniBooNE decays …
We compute the contribution of the decays $K_L \rightarrow π^0 Q \bar Q$ and $K^+ \rightarrow π^+ Q \bar Q$, where $Q$ is a dark fermion of the dark sector, to the measured widths for the rare decays $K^+\rightarrow π^+ ν\bar ν$ and $K_L\rightarrow π^0 ν\bar ν$. The recent experimental limit for $Γ(K^+ \rightarrow π^+ ν\bar ν)$ from NA62 sets a new and very strict bound on the dark-sector parameters. A branching ratio for $K_L \rightarrow π^0 Q \bar Q$ within the reach of the KOTO sensitivity is possible. The Grossman-Nir bound is weakened by the asymmetric effect of the different kinematic cu…
The search for light and long-lived particles at the LHC will be intensified in the upcoming years with a prominent role of the new FASER experiment. In this study, we discuss how FASER could independently probe such scenarios relevant for new physics searches at kaon factories. We put an emphasis on the proposed explanations for the recently observed three anomalous events in the KOTO experiment. The baseline of FASER precisely corresponds to the proposed lifetime solution to the anomaly that avoids the NA62 bounds on charged kaons. As a result, the experiment can start constraining relevant …
We consider a simple extension of the Standard Model (SM) by a complex scalar doublet and a singlet along with three sterile neutrinos. The sterile neutrinos mix with the SM neutrinos to produce three light neutrino states consistent with the oscillation data and three heavy sterile states. The lightest sterile neutrino has lifetime longer than the age of the Universe and can provide correct dark matter relic abundance. Utilizing tree-level flavor changing interactions of a light scalar with mass~$\sim\mathcal{O}(100)$~MeV along with sterile neutrinos, we can explain the anomalous magnetic mom…
The KOTO experiment has reported an excess of $K_L\toπ^0ν\barν$ events above the Standard Model prediction, in tension with the Grossman-Nir (GN) bound. The GN bound heavily constrains new physics interpretations of an excess in this channel, but another possibility is that the observed events originate from a different process entirely: a decay of the form $K_L\toπ^0X$, where $X$ denotes one or more new invisible species. We introduce a class of models to study this scenario with two light scalars playing the role of $X$, and we examine the possibility that the lighter of the two new states m…
KEK Theory Center, IPNS, KEK（高能加速器研究机构理论中心，粒子核物理研究部）；Graduate Institute for Advanced Studies, SOKENDAI（综合研究大学院大学高等研究院）；Department of Physics, The University of Osaka（大阪大学物理学系）
In the extensive efforts to understand the nature of Dark Matter and searches at colliders, the LHCb experiment has a unique sensitivity to low mass Dark Matter candidates. These proceedings present recent results and prospects on Dark Matter searches with the LHCb experiment that achieve world-leading sensitivities.
Rare decays of $K$ and $B$ mesons provide a powerful probe of dark sectors with light new particles. We show that the pair production of $O(100\,{\rm MeV})$ dark states can be probed with the decays of $K_L$ mesons, owing to the enhanced two-body kinematics, $K_L\to X_1X_2$ or $X_2X_2$. If either or these two particles is unstable, e.g. $X_2\to X_1π^0$, $X_2\to X_1γ$ or $X_{1,2}\to γγ$, such decays could easily mimic $K_L\to π^0 ν\overlineν$ signatures, while not being ruled out by the decays of charged kaons. We construct explicit models that have enhanced $K_L$ decay signatures, and are cons…
The presence of a non-baryonic Dark Matter (DM) component in the Universe is inferred from the observation of its gravitational interaction. The ATLAS and CMS experiments located at the LHC have developed a broad search program for DM candidates, including resonance searches for the mediator and searches with large missing transverse momentum. Additionally, searches have been conducted in models where the Higgs Sector and the Dark Sector are connected leading for example to invisible Higgs boson decays. The results of recent searches on 13 TeV $pp$ data, their interplay and interpretation are …
Direct detection experiments are gaining in mass reach. Here we show that the inclusion of dark Compton scattering, which has typically been neglected in absorption searches, has a substantial impact on the reach and discovery potential of direct detection experiments at high bosonic cold dark matter masses. We demonstrate this for relic dark photons and axion-like particles: we improve expected reach across materials, and further use results from SuperCDMS, EDELWEISS and GERDA to place enhanced limits on dark matter parameter space. We outline the implications for detector design and analysis…
Dark matter is the name assigned to one of the most important contemporary challenges that fundamental physics research is facing. In recent years, the hypothesis that dark matter might be "light" is gaining interest. Following this idea, dark matter particles belong to a new, unexplored dark sector, that is communicating with the Standard Model through one (or more) dark mediator particles. The mass scale of such dark sector particles, i.e. the mediators and the stable dark matter particles, could be comparable to the proton mass or below. Light dark matter would be very difficult to detect w…
Plots summarizing the constraints on Dark Matter models can help visualize synergies between different searches for the same kind of experiment, as well as between different experiments. In this whitepaper, we present an update to the European Strategy Briefing Book plots, from the perspective of collider searches within the Dark Matter at the Energy Frontier (EF10) Snowmass Topical Group, starting from inputs from future collider facilities. We take as a starting point the plots currently made for LHC searches using benchmark models recommended by the Dark Matter Working Group, also used for …
A glimpse into the most recent searches for Dark Matter at the LHC performed by the ATLAS and CMS collaborations is presented. The results covered in this document are all based on Run-2 proton-proton collision data recorded at $\sqrt{s}=13\text{ TeV}$ and corresponding to an integrated luminosity of just under 140 $\text{fb}^{-1}$
We explore the possibility of having a fermionic dark matter candidate within $U(1)'$ models for CE$ν$NS experiments in light of the latest COHERENT data and the current and future dark matter direct detection experiments. A vector-like fermionic dark matter has been introduced which is charged under $U(1)'$ symmetry, naturally stable after spontaneous symmetry breaking. We perform a complementary investigation using CE$ν$NS experiments and dark matter direct detection searches to explore dark matter as well as $Z^{\prime}$ boson parameter space. Depending on numerous other constraints arising…
Large panels of etched plastic, situated aboard the Skylab Space Station and inside the Ohya quarry near Tokyo, have been used to set limits on fluxes of cosmogenic particles. These plastic particle track detectors also provide the best sensitivity for some heavy dark matter that interacts strongly with nuclei. We revisit prior dark matter bounds from Skylab, and incorporate geometry-dependent thresholds, a halo velocity distribution, and a complete accounting of observed through-going particle fluxes. These considerations reduce the Skylab bound's mass range by a few orders of magnitude. Howe…
Collider signatures with top quarks provide sensitive probes of dark matter (DM) production at the Large Hadron Collider (LHC). In this article, we review the results of DM searches in final states with top quarks conducted by the ATLAS and CMS Collaborations at the LHC, including the most recent results on the full LHC Run 2 dataset. We highlight the complementarity of DM searches in final states with top quarks with searches in other final states in the framework of various simplified models of DM. A re-interpretation of a DM search with top quarks in the context of an effective-field theory…
罕见的K介子衰变提供了短距离物理学的灵敏探针。其中最有前途的模式是K+ --> pi+ nu anti-nu和K（L）--> pi 0 nu anti-nu模式，这是由于它们的理论清洁和专用实验，NA 62和KOTO。在这些模式下，新物理学搜索成功的关键是标准模型预测的精度。本文综述了它们的标准模型预测的现状和最新进展，并讨论了K（L）-> pi 0 l+ l-和K（L）-> mu+ mu-衰变的预测和新物理灵敏度。
In a recent letter we proposed a new non-thermal mechanism of Dark Matter production based on vacuum misalignment, where both the Higgs boson and a very light pseudo-scalar $η$ emerge from the Dark sector. In this letter, we identify the parameter space in a composite scenario where the light pseudo-scalar can be produced in the sun and explain the XENON1T excess in electron recoil data. The model's Dark Matter candidate has a mass around $50$ TeV and out of range for Direct Detection. Testable predictions include Gravitational waves at frequencies in the Hz range from a cosmological phase tra…
Prospects for $K_{L}\toπ^{0}ν\barν$, $K_S\toμ^+μ^-$, $K_L\toπ^0 \ell^+\ell^-$ and $\varepsilon^{\prime}/\varepsilon$ after the new $K^{+}\toπ^{+}ν\barν$ result from NA62
Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院）；University of Birmingham（伯明翰大学）；CERN（欧洲核子研究中心）
Very Heavy and Composite Dark Matter: Theory and Experimental Searches
Arthur B. McDonald Canadian Astroparticle Physics Research Institute（阿瑟·B·麦克唐纳加拿大高能粒子物理研究所）；Queen’s University（女王大学）；Perimeter Institute for Theoretical Physics（基础物理前沿研究所）
In this paper we study the possible searches at colliders using Vector Boson Fusion topology in the context of Simplified Models signatures. We examine the possible physics reach of these searches with regard to monojet-type searches, and determine how these two signatures are complementary.
Indirect searches for dark matter are based on detecting an anomalous flux of photons, neutrinos or cosmic-rays produced in annihilations or decays of dark matter candidates gravitationally accumulated in heavy cosmological objects, like galaxies, the Sun or the Earth. Additionally, evidence for dark matter that can also be understood as indirect can be obtained from early universe probes, like fluctuations of the Cosmic Microwave Background temperature, the primordial abundance of light elements or the Hydrogen 21-cm line. The techniques needed to detect these different signatures require ver…
