2,592 research outputs found
Cosmic Millicharge Background and Reheating Probes
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 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 MeV,
much lower than the previously considered upper bound from inflationary
cosmology at around 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
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 -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
-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
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 (), 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
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
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 . 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 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
mixing effects on charmonium and meson decays
We include the meson into the -- mixing formalism
constructed in our previous work, where 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 and is found to be about
from the measured decay widths of the meson. The pseudoscalar glueball
mass , the pseudoscalar densities and the U(1) anomaly
matrix elements associated with the mixed states are solved from the anomalous
Ward identities. The solution GeV obtained from the
-- mixing is confirmed, while grows to above the pion
mass, and thus increases perturbative QCD predictions for the branching ratios
. We then analyze the -mixing effects on charmonium
magnetic dipole transitions, and on the branching
ratios and CP asymmetries, which further improve the consistency between
theoretical predictions and data. A predominant observation is that the
mixing enhances the perturbative QCD predictions for
by 18%, but does not alter those for . The puzzle due to the
large data is then resolved.Comment: 12 pages, version to appear in PR
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