A
bstract
In many particle physics models, domain walls can form during the phase transition process after the breakdown of the discrete symmetry. Utilizing the ℤ
3
symmetric complex singlet scalar ...extension of the Standard Model, we study the gravitational waves produced by the strongly first-order electroweak phase transition and the domain wall decay. The gravitational wave spectrum is of a typical two-peak shape. The high frequency peak corresponding to the strongly first-order electroweak phase transition is able to be probed by the future space-based interferometers, and the low frequency peak coming from the domain wall decay is far beyond the capability of the current Pulsar Timing Arrays, and future Square Kilometer Array.
We study stochastic gravitational wave production and baryon number generation at electroweak phase transition with the two Higgs doublet models. The produced stochastic gravitational wave during the ...strongly first-order phase transition can be probed by future space-based interferometers. The nonlocal electroweak baryogenesis cannot address the observed Baryon asymmetry of the Universe successfully in the strongly first-order phase transition parameter spaces due to the CP violation phase is severely bounded by the electron electric dipole moment measurement ACMEII.
A
bstract
The type-II seesaw model is a possible candidate for simultaneously explaining non-vanishing neutrino masses and the observed baryon asymmetry of the Universe. In this work, we study in ...detail the pattern of phase transition and the gravitational wave production of this model. We find a strong first-order electroweak phase transition generically prefers positive Higgs portal couplings and a light triplet below ~ 550 GeV. In addition, we find the gravitational wave yield generated during the phase transition would be at the edge of BBO sensitivity and could be further examined by Ultimate-DECIGO.
We study the possibility of monopoles serving as dark matter when they are produced during the first-order phase transition in the dark sector. Our study shows that dark monopoles can contribute only ...a small piece of dark matter relic density within parameter spaces where strong gravitational waves can be probed by ET and CE, and the monopoles can contribute a sizable component of the observed dark matter relic density for fast phase transitions with short duration.
We investigate the temperature-dependent production of feebly interacting massive dark matter particle (FIMP DM) within a
Z
2
model, incorporating two
Z
2
-odd scalar fields. In specific parameter ...regions, three distinct mechanisms individually dominate the production of the FIMP DM. These mechanisms include the semi-production process, commonly known as the “exponential growth” process, the three-body decay process, and the production from pair annihilations of the bath particles. It is crucial to consider the thermal history during the evolution of FIMPs, as it involves multiple phase transitions occurring prior to the freeze-in of dark matter. Consequently, the scalar masses experience thermal variations, leading to distinctive evolutionary trajectories for FIMPs when compared to scenarios without accounting for the thermal effects. Notably, the unique patterns of FIMP evolution are accompanied by the production of gravitational waves, presenting promising opportunities for detection using forthcoming interferometers.
A
bstract
In this work, we perform the electroweak phase transition study with the Georgi-Machacek model. We investigate both the one-step and two-step strong first order electroweak phase transition ...(SFOEWPT). The SFOEWPT viable parameter spaces could be tested by the future 14TeV LHC, HL-LHC, and ILC. The LHC Higgs signal strength measurements severely bound the SFOEWPT valid parameter spaces, a tinny region of the mixing angle between the neutral fields of the isospin-doublet and isospin-triplet scalars around
α
∼ 0 can allow the two-step SFOEWPT to occur. The triplet vacuum expectation value (VEV) is crucial for both SFOEWPT and related Higgs phenomenology. The two-step SFOEWPT can be distinguished from the one-step SFOEWPT through the triple Higgs coupling searches and the low mass doubly charged Higgs searches at colliders.
In this paper, we discuss three modified single-field natural inflation models in detail, including Special generalized natural inflation model (SNI), extended natural inflation model (ENI) and ...natural inflation inspired model (NII). We derive the analytical expression of the tensor-to-scalar ratio
r
and the spectral index
n
s
for those models. Then the reheating temperature
T
re
and reheating duration
N
re
are analytically derived. Moreover, considering the CMB constraints, the feasible space of the SNI model in
(
n
s
,
r
)
plane is almost covered by that of the NII, which means the NII is more general than the SNI. In addition, there is no overlapping space between the ENI and the other two models in
(
n
s
,
r
)
plane, which indicates that the ENI and the other two models exclude each other, and more accurate experiments can verify them. Furthermore, the reheating brings tighter constraints to the inflation models, but they still work for a different reheating universe. Considering the constraints of
n
s
,
r
,
N
k
and choosing
T
re
near the electroweak energy scale, one can find that the decay constants of the three models have no overlapping area and the effective equations of state
ω
re
should be within
1
4
≲
ω
re
≲
4
5
for the three models.
We perform the three-dimensional lattice simulation of the magnetic field and gravitational wave productions from bubble collisions during the first-order electroweak phase transition. Except for the ...gravitational wave, the power-law spectrum of the magnetic field strength is numerically calculated for the first time, which is of a broken power-law spectrum: Bξ∝f0.91 for the low-frequency region of f<f⋆ and Bξ∝f−1.65 for the high-frequency region of f>f⋆ in the thin-wall limit, with the peak frequency being f⋆∼5 Hz at the phase transition temperature 100 GeV. When the hydrodynamics is taken into account, the generated magnetic field strength can reach Bξ∼10−7 G at a correlation length ξ∼10−7 pc, which may seed the large scale magnetic fields. Our study shows that the measurements of cosmic magnetic field strength and gravitational waves are complementary to probe new physics admitting electroweak phase transition.
The research and development of autonomous vehicle (AV) technology have been gaining ground globally. However, a few studies have performed an in-depth exploration of the contributing factors of ...crashes involving AVs. This study aims to predict the severity of crashes involving AVs and analyze the effects of the different factors on crash severity. Crash data were obtained from the AV-related crash reports presented to the California Department of Motor Vehicles in 2019 and included 75 uninjured and 18 injured accident cases. The points-of-interest (POI) data were collected from Google Map Application Programming Interface (API). Descriptive statistics analysis was applied to examine the features of crashes involving AVs in terms of collision type, crash severity, vehicle movement preceding the collision, and degree of vehicle damage. To compare the classification performance of different classifiers, we use two different classification models: eXtreme Gradient Boosting (XGBoost) and Classification and Regression Tree (CART). The result shows that the XGBoost model performs better in identifying the injured crashes involving AVs. Compared with the original XGBoost model, the recall and G-mean of the XGBoost model combining POI data improved by 100% and 11.1%, respectively. The main features that contribute to the severity of crashes include weather, degree of vehicle damage, accident location, and collision type. The results indicate that crash severity significantly increases if the AVs collided at an intersection under extreme weather conditions (e.g., fog and snow). Moreover, an accident resulting in injuries also had a higher probability of occurring in areas where land-use patterns are highly diverse. The knowledge gained from this research could ultimately contribute to assessing and improving the safety performance of the current AVs.
Cyanophages play important roles in regulating the population dynamics, community structure, metabolism, and evolution of cyanobacteria in aquatic ecosystems. Here, we report the genomic analysis of ...an estuarine cyanophage, S-CREM1, which represents a new genus of T4-like cyanomyovirus and exhibits new genetic characteristics. S-CREM1 is a lytic phage which infects estuarine
sp. CB0101. In contrast to many cyanomyoviruses that usually have a broad host range, S-CREM1 only infected the original host strain. In addition to cyanophage-featured auxiliary metabolic genes (AMGs), S-CREM1 also contains unique AMGs, including three antitoxin genes, a MoxR family ATPase gene, and a pyrimidine dimer DNA glycosylase gene. The finding of three antitoxin genes in S-CREM1 implies a possible phage control of host cells during infection. One small RNA (sRNA) gene and three
-regulatory RNA genes in the S-CREM1 genome suggest potential molecular regulations of host metabolism by the phage. In addition, S-CREM1 contains a large number of tRNA genes which may reflect a genomic adaption to the nutrient-rich environment. Our study suggests that we are still far from understanding the viral diversity in nature, and the complicated virus-host interactions remain to be discovered. The isolation and characterization of S-CREM1 further our understanding of the gene diversity of cyanophages and phage-host interactions in the estuarine environment.
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