The Belle II collaboration recently announced that they observed the $B^+
\!\to K^+\nu\bar{\nu}$ decay process for the first time. This dineutrino mode
of $B^+ \!\to K^+\nu\bar{\nu}$ has been ...theoretically identified as a very
clean channel. However, their result encounters a $2.7{}^{}\sigma$ deviation
from the Standard Model (SM) calculation. On the other hand, last year,
Fermilab released new data on muon $g-2$ away from the SM expectation with
$5{}^{}\sigma$. In this letter, we study the simplest UV-complete
$\text{U}(1)_{\textsf{L}_\mu - \textsf{L}_\tau}^{}$-charged complex scalar Dark
Matter (DM) model. Thanks to the existence of light dark Higgs boson and light
dark photon, we can explain the observed relic density of DM and resolve the
results reported by both Belle II and Fermilab experiments simultaneously. As a
byproduct, the Hubble tension is alleviated by taking $\Delta N_\textsf{eff}^{}
\simeq 0.3$ induced by the light dark photon.
In this work, we revisit pseudo Nambu Goldstone boson (pNGB) DM model where global \(U(1)\) dark symmetry is spontaneously broken as well as explicitly with broken by with linear symmetry breaking, ...focusing on the dark matter mass range in \(500 {\rm GeV} \lesssim m_{\rm DM} \lesssim O(10)\) TeV. This model is interesting not only in its own in the context of pNGB DM, but also in the context of cosmological collider signatures from heavy particle mass regime without Boltzmann suppressions, \(H \lesssim m_{\rm heavy} \lesssim 60 H\), through the chemical potential type interaction. After imposing perturbative unitarity, perturbativity, correct thermal relic density and constraints from colliders and (in)direct detection experiments, we find that pNGB DM mass is allowed up to \(\sim 1 (10)\) TeV for the dark Higgs mass \(m_{H_2} = 1 (100)\) TeV for the Higgs-dark Higgs mixing \(\sin \theta = 0.1\). We also consider the case where global \(U(1)\) dark symmetry is not spontaneously broken, where DM is no longer pNGB. In this case, DM and dark Higgs masses are nearly degenerate in the range of a few TeV \(\lesssim m_{{\rm DM}, H_2} \lesssim \sim 70\) TeV. Low mass region for pNGB DM and \(H_2\) could be directly probed in colliders or indirect DM detections, whereas the heavy mass regime could be probed through the non-Gaussianity at the level of \(f_{\rm NL} \sim O(0.01-10)\) if \(H\) is as low as \(O(1-10)\) TeV.
We propose a unified solution with $Z_4$ discrete symmetry for small neutrino
masses and stability of dark matter. Our model consists of an inert doublet
scalar, a dark singlet scalar $S$, a spurion ...scalar $\varphi$ and right-handed
neutrinos beyond the Standard Model (SM), which transform nontrivially under
$Z_4$. Once the $Z_4$ symmetry is broken to $Z_2$ by the VEV of $\varphi$, much
below the mass scale of the singlet scalar $S$, a small quartic coupling
between SM Higgs and inert doublets, which violates both $Z_4$ and lepton
number, is generated at tree level, so small neutrino masses are obtained at
one-loops. We discuss the consistent parameter space for neutrino masses,
direct detection and thermal leptogenesis in the model.
We consider the axion-mediated scattering processes between dark matter (DM) and nucleus. Substantial contributions are made via the CP-odd gluonic current which induces the spin-dependent process. ...Since the QCD axion is too feebly coupled to the visible particles, non-QCD axions are necessary for the current DM experiments to accomplish the ample sensitivity. In the case of multi-component DM models, the inelastic scattering processes also make sizable contributions to the direct detection. The supersymmetry (SUSY) and clockwork (CW) mechanism provide a realistic model for the QCD and non-QCD axions and the axion-mediated DM scattering processes. In the SUSY CW axion model, the lightest axino is the DM particle and the axions mediate the elastic and inelastic scattering processes. We show that the current and future XENONnT can produce relevant constraints for some parameter space of the model.
Schwann cells are glial cells that are responsible for the synthesis and maintenance of the myelin sheath in the peripheral nerve system. Under pathological conditions, such as physical nerve injury ...and inflammatory neuropathies, Schwann cells undergo a substantial phenotype transformation that is not related to their intended function. For example, Schwann cells dedifferentiate into immature states and thereby cease to express myelin genes after nerve injury.
We consider the possibility that the weakly interacting massive particles produced from the evaporation of primordial black hole can explain both the relic density of dark matter and the baryon ...asymmetry of the Universe, through their annihilation which violate B and CP-symmetry. We find that the primordial black hole with mass less than \(10^7 {\rm g}\) is a good candidate as an source of TeV dark matter with the total annihilation cross section \(\left\langle\sigma_a \upsilon\right\rangle \lesssim 10^{-7} \ {\rm GeV}^{-2}\) and the B-violating scattering cross section \(\left\langle\sigma_B \upsilon\right\rangle \lesssim 2\times 10^{-9} \ {\rm GeV^{-2}}\). This large annihilation cross section of dark matter in this model would make it available to search them in the indirect search for dark matter such as gamma-ray or neutrino observations.
The recent measurement of muon anomalous magnetic dipole moment (muon \(g-2\)) suggests that there might exist new physics that dominantly interacts with muons. The observed gamma-ray excess from ...Fermi-LAT indicates that dark matter annihilates into a specific charged fermions. We propose a successful model simultaneously to explain the Fermi-LAT GeV gamma-ray excess and sizable muon \(g-2\) with a modular \(A_4\) symmetry. Due to nature of this symmetry, our DM only interacts with pairs of muon and we explain sizable muon \(g-2\) without suffering from constraints of any lepton flavor violations. We numerically show our allowed spaces on each measurements of Fermi-LAT, relic density of DM and muon \(g-2\), randomly scanning our input parameters.
We explore muon anomalous magnetic moment (muon $g-2$) in a scotogenic
neutrino model with a gauged lepton number symmetry $U(1)_{\mu-\tau}$. In this
model, a dominant muon $g-2$ contribution comes ...not from an additional gauge
sector but from a Yukawa sector. In our numerical $\Delta \chi^2$ analysis, we
show that our model is in favor of normal hierarchy with some features. We
demonstrate one benchmark point, satisfying muon $g-2$ at the best fit value
$25.1\times10^{-10}$.
Phys.Rev.D 107 (2023) 7, 075002 In this paper, we evaluate the energy loss rate of supernovae induced by the
axion emission process $\pi^- + p \to n + a$ with the $\Delta(1232)$ resonance
in the ...heavy baryon chiral perturbation theory for the first time. Given the
axion-nucleon-$\Delta$ interactions, we include the previously ignored
$\Delta$-mediated graphs to the $\pi^- + p \to n + a$ process. In particular,
the $\Delta^0$-mediated diagram can give a resonance contribution to the
supernova axion emission rate when the center-of-mass energy of the pion and
proton approaches the $\Delta(1232)$ mass. With these new contributions, we
find that for the typical supernova temperatures, compared with the earlier
work with the axion-nucleon (and axion-pion-nucleon contact) interactions, the
supernova axion emissivity can be enhanced by a factor of $\sim$4(2) in the
Kim-Shifman-Vainshtein-Zakharov model and up to a factor of $\sim$5(2) in the
Dine-Fischler-Srednicki-Zhitnitsky model with small $\tan\beta$ values.
Remarkably, we notice that the $\Delta(1232)$ resonance gives a destructive
contribution to the supernova axion emission rate at high supernova
temperatures, which is a nontrivial result in this study.
It is clear that matter is dominant in the Universe compared to antimatter.
We call this problem baryon asymmetry. The baryon asymmetry is experimentally
determined by both cosmic microwave ...background and big bang nucleosynthesis
measurements. To resolve the baryon number asymmetry of the Universe as well as
neutrino oscillations, we study a radiative seesaw model in a modular $A_4$
symmetry. Degenerate heavy Majorana neutrino masses can be naturally realized
in an appropriate assignments under modular $A_4$ with large imaginary part of
modulus $\tau$, and it can induce measured baryon number via resonant
leptogenesis that is valid in around TeV scale energy theory. We also find that
the dominant contribution to the CP asymmetry arises from Re$\tau$ through
our numerical analysis satisfying the neutrino oscillation data.
PDF