2,396 research outputs found

    Cosmic Millicharge Background and Reheating Probes

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    We demonstrate that the searches for dark sector particles can provide probes of reheating scenarios, focusing on the cosmic millicharge background produced in the early universe. We discuss two types of millicharge particles (mCPs): either with, or without, an accompanying dark photon. These two types of mCPs have distinct theoretical motivations and cosmological signatures. We discuss constraints from the overproduction and mCP-baryon interactions of the mCP without an accompanying dark photon, with different reheating temperatures. We also consider the ΔNeff\Delta N_{\rm eff} constraints on the mCPs from kinetic mixing, varying the reheating temperature. The regions of interest in which the accelerator and other experiments can probe the reheating scenarios are identified in this paper for both scenarios. These probes can potentially allow us to set an upper bound on the reheating temperature down to 10\sim 10 MeV, much lower than the previously considered upper bound from inflationary cosmology at around 1016\sim 10^{16} GeV. In addition, we find parameter regions in which the two mCP scenarios may be differentiated by cosmological considerations. Finally, we discuss the implications of dedicated mCP searches and future CMB-S4 observations.Comment: 10 pages plus references, 5 figure

    Resonant Self-Interacting Dark Matter from Dark QCD

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    We present models of resonant self-interacting dark matter in a dark sector with QCD, based on analogies to the meson spectra in Standard Model QCD. For dark mesons made of two light quarks, we present a simple model that realizes resonant self-interaction (analogous to the ϕ\phi-K-K system) and thermal freeze-out. We also consider asymmetric dark matter composed of heavy and light dark quarks to realize a resonant self-interaction (analogous to the Υ(4S)\Upsilon(4S)-B-B system) and discuss the experimental probes of both setups. Finally, we comment on the possible resonant self-interactions already built into SIMP and ELDER mechanisms while making use of lattice results to determine feasibility.Comment: 10 pages, 5 figure

    Heavy Neutral Leptons at Beam Dump Experiments of Future Lepton Colliders

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    A new beam dump experiment that utilizes the beam of future high energy electron-positron colliders could be an excellent avenue to search for dark sector particles due to its unprecedented high energy and intensity. We consider heavy neutral leptons (HNLs) as a specific example to demonstrate the sensitivity of searches for dark sector particles at future electron-positron collider beam dump experiments. This includes the study of the reach at the International Linear Collider (ILC), the Cool Copper Collider (C3\rm C^3), and the Compact Linear Collider (CLIC). We comprehensively examine the HNL production and detector acceptance at these electron beam dump experiments. We show that these experiments will probe a large range of HNL parameter space, not yet probed by past experiments. These experiments will be complementary to other proposed experiments such as proton beam dump experiments, neutrino experiments, and LHC auxiliary detectors. Our study also motivates a more detailed analysis of heavy meson productions in high-energy electron-nucleon collisions in thick targets.Comment: v2: References added. Conclusions unchange

    Dipole portal to heavy neutral leptons

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    We consider generic neutrino dipole portals between left-handed neutrinos, photons, and right-handed heavy neutral leptons (HNL) with Dirac masses. The dominance of this portal significantly alters the conventional phenomenology of HNLs. We derive a comprehensive set of constraints on the dipole portal to HNLs by utilizing data from LEP, LHC, MiniBooNE, LSND as well as observations of Supernova 1987A and consistency of the standard Big Bang Nucleosynthesis. We calculate projected sensitivities from the proposed high-intensity SHiP beam dump experiment, and the ongoing experiments at the Short-Baseline Neutrino facility at Fermilab. Dipole mediated Primakoff neutrino upscattering and Dalitz-like meson decays are found to be the main production mechanisms in most of the parametric regime under consideration. Proposed explanations of LSND and MiniBooNE anomalies based on HNLs with dipole-induced decays are found to be severely constrained, or to be tested in the future experiments.Comment: 26 pages, 11 figure

    Asteroid g-2 experiments: new fifth force and ultralight dark sector tests

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    We study for the first time the possibility of probing long-range fifth forces utilizing asteroid astrometric data, via the fifth force-induced orbital precession. We examine nine Near-Earth Object (NEO) asteroids whose orbital trajectories are accurately determined via optical and radar astrometry. Focusing on a Yukawa-type potential mediated by a new gauge field (dark photon) or a baryon-coupled scalar, we estimate the sensitivity reach for the fifth-force coupling strength and mediator mass in the mass range m10211015eVm \simeq 10^{-21}-10^{-15}\,{\rm eV}. Our estimated sensitivity is comparable to leading limits from torsion balance experiments, potentially exceeding these in a specific mass range. The fifth forced-induced precession increases with the orbital semi-major axis in the small mm limit, motivating the study of objects further away from the Sun. We discuss future exciting prospects for extending our study to more than a million asteroids (including NEOs, main-belt asteroids, Hildas, and Jupiter Trojans), as well as trans-Neptunian objects and exoplanets.Comment: 2 figures, 1 table, 5 pages + reference

    ηc\eta_c mixing effects on charmonium and BB meson decays

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    We include the ηc\eta_c meson into the η\eta-η\eta'-GG mixing formalism constructed in our previous work, where GG represents the pseudoscalar gluball. The mixing angles in this tetramixing matrix are constrained by theoretical and experimental implications from relevant hadronic processes. Especially, the angle between ηc\eta_c and GG is found to be about 1111^\circ from the measured decay widths of the ηc\eta_c meson. The pseudoscalar glueball mass mGm_G, the pseudoscalar densities mqq,ss,ccm_{qq,ss,cc} and the U(1) anomaly matrix elements associated with the mixed states are solved from the anomalous Ward identities. The solution mG1.4m_G\approx 1.4 GeV obtained from the η\eta-η\eta'-GG mixing is confirmed, while mqqm_{qq} grows to above the pion mass, and thus increases perturbative QCD predictions for the branching ratios Br(BηK)Br(B\to\eta'K). We then analyze the ηc\eta_c-mixing effects on charmonium magnetic dipole transitions, and on the Bη()KSB\to\eta^{(\prime)}K_S branching ratios and CP asymmetries, which further improve the consistency between theoretical predictions and data. A predominant observation is that the ηc\eta_c mixing enhances the perturbative QCD predictions for Br(BηK)Br(B\to\eta'K) by 18%, but does not alter those for Br(BηK)Br(B\to\eta K). The puzzle due to the large Br(BηK)Br(B\to\eta'K) data is then resolved.Comment: 12 pages, version to appear in PR