Article
Astronomy & Astrophysics
Xin-zhe Zhang, Lei-Hua Liu, Taotao Qiu
Summary: In this paper, the primordial perturbations of the inflation model induced from the multifield mimetic gravity are investigated. Both adiabatic and isocurvature perturbation modes are generated in the presence of two fields during inflation. It is shown that the adiabatic perturbation mode can be transferred from the isocurvature one by applying the curvaton mechanism, thus solving the nonpropagating problem. Detailed calculations are performed for different epochs, indicating that the multifield mimetic inflation models are not affected by this nonpropagating problem.
Article
Astronomy & Astrophysics
Lei-Hua Liu, Tomislav Prokopec
Summary: This study investigates scalar cosmological perturbations generated through nonminimal coupling in two-field inflationary models with a focus on curvaton scenarios. It shows that small, negative nonminimal couplings can contribute to a redder curvature spectrum, potentially saving some curvaton scenarios that would otherwise be ruled out. The study also highlights the impact of nonminimal coupling on the postinflationary growth of the spectator perturbation and the effectiveness of the curvaton mechanism.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2021)
Article
Astronomy & Astrophysics
L. F. Guimaraes, F. T. Falciano
Summary: This paper presents a method for reconstructing the curvaton potential from a scale-dependent non-Gaussianity parameter, with an example of a weakly self-interacting curvaton model that satisfies observational constraints and explains CMB dipolar modulation. The approach can be extended to reconstruct the curvaton potential from the g(NL) parameter.
Article
Astronomy & Astrophysics
Lei-Hua Liu, Bin Liang, Ya-Chen Zhou, Xiao-Dan Liu, Wu-Long Xu, Ai-Chen Li
Summary: The study on the non-Gaussianity of canonical curvaton scenario using a generalized delta N formalism reveals that most parameter spaces are consistent with observational constraints. The research shows that the well-known parameter values can be accurately recovered in the absence of nonlinear evolution.
Article
Astronomy & Astrophysics
Alexander Y. Kamenshchik, Alessandro Tronconi, Giovanni Venturi
Summary: This study examines a possible amplification mechanism for curvature perturbations generated during inflation by a Dirac-Born-Infeld (DBI) inflaton in the presence of a sharp feature in the warp factor. The large growth in the scalar power spectrum is a result of the decreasing speed of sound. Analytical approximate expressions for relevant dynamical quantities in both the slow roll phase and the transient phase leading to amplification are obtained. Finally, a comparison is made between the approximations and the exact numerical evolution, and general rules for building a viable inflationary model that leads to abundant primordial black hole formation during the subsequent radiation dominated era are given.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Particles & Fields
Narges Rashidi, Kourosh Nozari
Summary: We studied intermediate inflation in the mimetic Dirac-Born-Infeld model and found that in certain parameter ranges, ghost and gradient instabilities can be avoided. We investigated scalar spectral index, tensor spectral index, and tensor-to-scalar ratio, comparing the results with observational data and obtaining observationally viable perturbation and non-Gaussianity parameters within specific parameter values.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Tomo Takahashi, Toshifumi Yamada, Shuichiro Yokoyama
Summary: In this study, we propose a multi-field inflation framework that includes two inflatons and a curvaton contributing to primordial fluctuations, consistent with current constraints. We also show that this framework can explain the baryon asymmetry of the Universe through leptogenesis via the decay of the lightest sneutrino. The parameter range, including sneutrino masses, for the scenario to work is investigated, with the tensor-to-scalar ratio found to be larger than 10-4 for successful implementation.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Physics, Nuclear
Lei-Hua Liu
Summary: In this study, building on previous research, we investigate the possibility of the formation of a primordial black hole, and its connection with dark energy and dark matter. Our findings show that our model can account for dark matter and sheds new light on exploring Higgs physics.
Article
Physics, Multidisciplinary
Keisuke Inomata, Masahiro Kawasaki, Kyohei Mukaida, Tsutomu T. Yanagida
Summary: The study suggests that the axionlike curvaton model can explain the primordial black holes in both the LIGO-Virgo events and NANOGrav results, with the non-Gaussianity suppressing the gravitational waves associated with PBHs.
PHYSICAL REVIEW LETTERS
(2021)
Article
Energy & Fuels
Dan Liu, Tiemin Xuan, Zhixia He, Mingfa Yao, Raul Payri
Summary: Nowadays, the Diffused Background-illumination Extinction Imaging technique (DBI) is widely used to quantitatively analyze the soot formation in diesel-like sprays. To eliminate errors caused by flame radiation, soot radiation images are recorded between every two back light-on pulses. This study applies the Super SloMo machine-learning method to generate missing frames and evaluates the accuracy of the interpolated frames based on frame interval length, prediction region, and number of intermediate frames. The results show that the Super SloMo method consistently outperforms the Gunner Farneba ck method in terms of accuracy, leading to a 26.4% reduction in average KL error.
Article
Astronomy & Astrophysics
Ryota Fujii, Sota Hanazawa, Hiraki Kanehisa, Makoto Sakaguchi
Summary: This paper examines the Becchi-Rouet-Stora-Tyutin (BRST) invariance of the open pure spinor superstring in the presence of background superfields on a Dp-brane. It is shown that the background superfields introduced in this paper depend on boundary fermions. The BRST invariance leads to supersymmetric Dirac-Born-Infeld (DBI) equations for background superfields depending on boundary fermions as well as boundary conditions on spacetime coordinates. After quantizing boundary fermions, background superfields are promoted to non-Abelian ones. As a result, we obtain the supersymmetric non-Abelian DBI equations from the supersymmetric DBI equations depending on boundary fermions. It is shown that these non-Abelian DBI equations reduce to the super-Yang-Mills equations in the limit α'→0. We also demonstrate the nilpotency of the BRST transformation of boundary fermions.
Article
Physics, Particles & Fields
Xiaokun Yang, Wu-Long Xu, Yong-Chang Huang
Summary: The DBI field theory in string theory plays an important role in providing the field for the inflation of the universe and causal mechanism for density perturbation. It is consistent with experimental constraints and presents a new way to explain the inflation of the universe.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Computer Science, Information Systems
Young Bi Lee, Jae Hyuk Suk, Dong Hoon Lee
Summary: This study found that in order to successfully analyze protected malware, dynamic binary instrumentation (DBI) should be used in a virtual environment, while bypassing anti-VM and anti-DBI techniques supported by commercial protectors. It is generally difficult for analysts to bypass these techniques used in commercial protectors.
Article
Thermodynamics
Ted Lind, Zheming Li, Rajavasanth Rajasegar, Gregory Roberts, Oivind Andersson, Mark P. B. Musculus
Summary: To meet emissions regulations, it is important to understand in-cylinder soot formation and oxidation processes. In this study, the DBI-TI technique is used to measure soot temperature in an optical diesel engine, and its potential and accuracy as a thermometry technique are analyzed. The results show that DBI-TI provides temperature estimates closer to the average soot temperature, and its accuracy is comparable or even better than other established optical thermometry techniques within the tested range of optical density and light intensity.
COMBUSTION AND FLAME
(2022)
Editorial Material
Cell Biology
Lea Montegut, Adrien Joseph, Hui Chena, Mahmoud Abdellatif, Christoph Ruckenstuhlg, Isabelle Martins, Frank Madeo, Guido Kroemer
Summary: DBI/ACBP is a conserved paracrine inhibitor that regulates autophagy and lifespan. Its increased levels in humans are associated with biological age and cardiovascular disease risk factors. Studies have shown that neutralizing DBI/ACBP can alleviate cardiac aging. Therefore, it may serve as a potential target for treating age-associated cardiovascular diseases.
Article
Astronomy & Astrophysics
Zihan Zhou, Jun Yan, Andrea Addazi, Yi-Fu Cai, Antonino Marciano, Roman Pasechnik
Summary: This study introduces a novel phenomenon in particle cosmology, where specific cosmological phase transitions are triggered by quantum tunneling through multiple vacua. This mechanism predicts a potentially significant new source of gravitational waves with distinct energy spectrum patterns, which could be detected by future gravitational wave interferometers.
Article
Astronomy & Astrophysics
Pierre Zhang, Guido D'Amico, Leonardo Senatore, Cheng Zhao, Yifu Cai
Summary: By analyzing the Full Shape of the BOSS Correlation Function and combining it with other measurements, we have determined the present day Hubble constant, matter fraction, and parameters of the primordial power spectrum. We have also placed constraints on the total neutrino mass. These results are consistent with previous studies and show no tension or inconsistency.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Pierre Zhang, Yifu Cai
Summary: The study re-analyzed the full shape of the BOSS galaxy two-point function within Lambda-CDM, with results constraining various cosmological parameters. The effect of redshift selection on the results was discussed, emphasizing the importance of systematic assessments for ongoing and future large-volume surveys.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Article
Astronomy & Astrophysics
Xin Ren, Sheng-Feng Yan, Yaqi Zhao, Yi-Fu Cai, Emmanuel N. Saridakis
Summary: In this study, we investigate the effective field theory formulation of torsional gravity in a cosmological framework and reconstruct the f(T) form in a model-independent way. By considering observational data and performing fitting using polynomial functions, we find an analytic expression that describes the cosmological evolution in great agreement with observations.
ASTROPHYSICAL JOURNAL
(2022)
Article
Astronomy & Astrophysics
Yi-Fu Cai, Xiao-Han Ma, Misao Sasaki, Dong-Gang Wang, Zihan Zhou
Summary: This study reports a novel prediction from single-field inflation that a tiny step in the inflaton potential can alter our understanding of primordial non-Gaussianities of the curvature perturbation. By analyzing the tail of the probability distribution generated by an upward step transition between two stages of slow-roll evolution, it is found that a highly non-Gaussian tail can be generated even when the conventional nonlinearity parameters remain small. This research demonstrates for the first time the sensitive dependence of non-perturbative effects on the tail of the probability distribution and proposes potential applications to primordial black holes.
Article
Astronomy & Astrophysics
Yi-Fu Cai, Xiao-Han Ma, Misao Sasaki, Dong-Gang Wang, Zihan Zhoua
Summary: This paper investigates the relationship between deviations from Gaussian statistics in primordial perturbations and non-perturbative effects. It presents specific examples where the tail of the distribution becomes highly non-Gaussian despite remaining almost Gaussian in the perturbative regime. The study reveals the rich phenomenology of non-Gaussian tails, which has been overlooked in conventional analyses.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2022)
Editorial Material
Physics, Multidisciplinary
Yi-Fu Cai
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2022)
Article
Physics, Multidisciplinary
Guan-Wen Yuan, Lei Zu, Lei Feng, Yi-Fu Cai, Yi-Zhong Fan
Summary: This study investigates new particles and fields to explain the excess in W-boson mass. The interpretations of axion-like particle and dark photon have been significantly narrowed down by global electroweak fits. The possibility of attributing the W-boson mass anomaly to chameleon dark energy is ruled out by other experiments.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2022)
Article
Multidisciplinary Sciences
Hang Liang, Man Jiao, Yue Huang, Pei Yu, Xiangyu Ye, Ya Wang, Yijin Xie, Yi-Fu Cai, Xing Rong, Jiangfeng Du
Summary: Laboratory search for exotic interactions is crucial for exploring physics beyond the standard model. We report new experimental constraints on two exotic spin-dependent interactions at the micrometer scale based on ensembles of nitrogen-vacancy (NV) centers in diamond. Our results establish new bounds for these exotic spin interactions at the micrometer scale.
NATIONAL SCIENCE REVIEW
(2023)
Article
Astronomy & Astrophysics
Dongdong Zhang, Jia-Rui Li, Jiaqi Yang, Yufei Zhang, Yi-Fu Cai, Wenjuan Fang, Chang Feng
Summary: We use the Ali Cosmic Microwave Background Polarization Telescope (AliCPT) to forecast the constraints on neutrino physics parameters using the Cosmic Microwave Background (CMB) temperature, E-mode polarization, and lensing spectra. Our numerical simulations show that AliCPT can achieve a precision of sigma(N (eff)) = 0.56 and M (nu) < 1.10 eV (95% CL.) for the first year of observation, based on TT, TE, EE, and CMB lensing power spectra. We also investigate how instrumental parameters such as noise level, FWHM, and sky coverage affect these constraints on neutrino parameters.
ASTROPHYSICAL JOURNAL
(2023)
Article
Physics, Multidisciplinary
Tinggui Wang, Guilin Liu, Zhenyi Cai, Jinjun Geng, Min Fang, Haoning He, Ji-an Jiang, Ning Jiang, Xu Kong, Bin Li, Ye Li, Wentao Luo, Zhizheng Pan, Xuefeng Wu, Ji Yang, Jiming Yu, Xianzhong Zheng, Qingfeng Zhu, Yi-Fu Cai, Yuanyuan Chen, Zhiwei Chen, Zigao Dai, Lulu Fan, Yizhong Fan, Wenjuan Fang, Zhicheng He, Lei Hu, Maokai Hu, Zhiping Jin, Zhibo Jiang, Guoliang Li, Fan Li, Xuzhi Li, Runduo Liang, Zheyu Lin, Qingzhong Liu, Wenhao Liu, Zhengyan Liu, Wei Liu, Yao Liu, Zheng Lou, Han Qu, Zhenfeng Sheng, Jianchun Shi, Yiping Shu, Zhenbo Su, Tianrui Sun, Hongchi Wang, Huiyuan Wang, Jian Wang, Junxian Wang, Daming Wei, Junjie Wei, Yongquan Xue, Jingzhi Yan, Chao Yang, Ye Yuan, Yefei Yuan, Hongxin Zhang, Miaomiao Zhang, Haibin Zhao, Wen Zhao
Summary: The Wide Field Survey Telescope (WFST) is a dedicated photometric surveying facility being built jointly by University of Science and Technology of China (USTC) and the Purple Mountain Observatory (PMO). It is equipped with a 2.5-meter diameter primary mirror and a mosaic CCD camera, and it will scan the northern sky in four optical bands to detect transient phenomena and study the variability of Galactic and extragalactic objects.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2023)
Article
Astronomy & Astrophysics
Lei-Hua Liu, Mian Zhu, Wentao Luo, Yi-Fu Cai, Yi Wang
Summary: We systematically investigate the microlensing effect of a charged spherically symmetric wormhole, where the light source is remote from the throat. The numerical result shows that the range of total magnification is from 105 to 10-2 depending on various metrics. Our theoretical investigation could shed new light on exploring the wormhole with the microlensing effect.
Article
Astronomy & Astrophysics
Yu-Min Hu, Yaqi Zhao, Xin Ren, Bo Wang, Emmanuel N. Saridakis, Yi-Fu Cai
Summary: This study investigates the scalar perturbations and possible strong coupling issues of f(T) gravity using the effective field theory (EFT) approach. The generalized EFT framework of modified teleparallel gravity is revisited and applied to examine both linear and second-order perturbations in f(T) theory. The results suggest that there is no new scalar mode present in f(T) gravity, indicating a strong coupling problem. However, an estimation of the strong coupling scale based on the ratio of cubic to quadratic Lagrangians shows that the strong coupling problem can be avoided for certain modes.
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2023)
Article
Astronomy & Astrophysics
Yiqi Huang, Jiajun Zhang, Xin Ren, Emmanuel N. Saridakis, Fuyu Dong, Yi-Fu Cai
Summary: In this study, we perform N-body simulations to investigate the structure formation process in f(T) gravity. By comparing with ACDM cosmology, we find clear observational differences due to the modifications brought about by f(T) gravity in the evolution of the Hubble function and the effective Newton's constant. We extract several physical quantities and observe differences in the matter density distribution, matter power spectrum, counts-in-cells, halo mass function, and excess surface density around low-density positions.
Article
Physics, Particles & Fields
Yi-Fu Cai, Chao Chen, Qianhang Ding, Yi Wang
Summary: A novel class of celestial objects called stellar bubbles, dominated by primordial black holes, is proposed, which can be generated through phase transitions in the primordial Universe. The radiations emitted by these stellar bubbles have distinct features in the gamma-ray spectra and gravitational waves.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Nelson R. F. Braga, Octavio C. Junqueira
Summary: This study investigates the influence of rotation on the transition temperature of strongly interacting matter produced in non-central heavy ion collisions. By using a holographic description of an AdS black hole, the authors extend the analysis to the more realistic case where the matter spreads over a region around the rotational axis. The results show the coexistence of confined and deconfined phases and are consistent with the concept of local temperature in rotating frames developed by Tolman and Ehrenfest.
Article
Astronomy & Astrophysics
Bing Sun, Jiachen An, Zhoujian Cao
Summary: This paper investigates the effect of gravitational constant variation on the propagation of gravitational waves. By employing two analytical methods, the study finds that variations in the gravitational constant result in amplitude and phase corrections for gravitational waves, and the time variation of the gravitational constant can be constrained through the propagation of gravitational waves.
Article
Astronomy & Astrophysics
Abdellah Touati, Zaim Slimane
Summary: This letter presents the first study of Hawking radiation as a tunneling process within the framework of non-commutative gauge theory of gravity. The non-commutative Schwarzschild black hole is reconstructed using the Seiberg-Witten map and the star product. The emission spectrum of outgoing massless particles is computed using the quantum tunneling mechanism. The results reveal pure thermal radiation in the low-frequency scenario, but a deviation from pure thermal radiation in the high-frequency scenario due to energy conservation. It is also found that noncommutativity enhances the correlations between successively emitted particles.
Article
Astronomy & Astrophysics
Shahar Hod
Summary: The travel times of light signals between two antipodal points on a compact star's surface are calculated for two different trajectories. It is shown that, for highly dense stars, the longer trajectory along the surface may have a shorter travel time as measured by asymptotic observers. A critical value of the dimensionless density-area parameter is determined for constant density stars to distinguish cases where crossing through the star's center or following a semi-circular trajectory on the surface has a shorter travel time as measured by asymptotic observers.
