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A refined trans-Planckian censorship conjecture

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Science China(Physics,Mechanics & Astronomy) 2021年第1期64卷 33-40页

作者： Rong-Gen Cai shao-jiang wang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing100190China Tufts Institute of Cosmology Department of Physics and AstronomyTufts UniversityMedford02155USA

We propose a refined version of trans-Planckian censorship conjecture(TCC), which could be elaborated from the strong scalar weak gravity conjecture combined with some entropy bounds. In particular, no fine-tuning on the inflation model-building is required in the refined TCC, and it automatically passes the tests from those stringy examples that support the original ***, our refined TCC could be consistent with hilltop eternal inflation.

关键词： inflation swampland conjectures weak gravity conjecture

Energy budget of cosmological first-order phase transition in FLRW background

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Science China(Physics,Mechanics & Astronomy) 2018年第8期61卷 33-53页

作者： Rong-Gen Cai shao-jiang wang Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China Department of Physics Helsinki Institute of PhysicsUniversity of HelsinkiHelsinki F1-00014Finland School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China

We study the hydrodynamics of bubble expansion in cosmological first-order phase transition in the Fdedmann-LemMtre- Robertson-Walker （FLRW） background with probe limit. Different from previous studies for fast first-order phase transition in flat background, we find that, for slow first-order phase transition in FLRW background with a given peculiar velocity of the bubble wall, the efficiency factor of energy transfer into bulk motion of thermal fluid is significantly reduced, thus decreasing the previously-thought dominated contribution from sound wave to the stochastic gravitational-wave background.

关键词： cosmological first-order phase transition bubble expansion hydrodynamics

Gravitational waves and primordial black hole productions from gluodynamics by holography

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Science China(Physics,Mechanics & Astronomy) 2024年第4期67卷 31-42页

作者： Song He Li Li Zhibin Li shao-jiang wang Center for Theoretical Physics and College of Physics Jilin UniversityChangchun 130012China Max Planck Institute for Gravitational Physics(Albert Einstein Institute) Golm 14476Germany CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China Peng Huanwu Collaborative Center for Research and Education Beihang UniversityBeijing 100191China School of Physics and Microelectronics Zhengzhou UniversityZhengzhou 450001China

Understanding the nature of quantum chromodynamics(QCD)matter is important but challenging due to the presence of nonperturbative dynamics under extreme *** construct a holographic model describing the gluon sector of QCD at finite temperatures in the non-perturbative *** equation of state as a function of temperature is in good accordance with the lattice QCD ***,the Polyakov loop and the gluon condensation,which are proper order parameters to capture the deconfinement phase transition,also agree quantitatively well with the lattice QCD *** obtain a strong first-order confinement/deconfinement phase transition at Tc=276.5 Me V that is consistent with the lattice QCD *** on our model for a pure gluon hidden sector,we compute the stochastic gravitational waves and primordial black hole(PBH)productions from this confinement/deconfinement phase transition in the early *** resulting stochastic gravitational-wave backgrounds are found to be within detectability in the International Pulsar Timing Array and Square Kilometre Array in the near future when the associated productions of PBHs saturate the current observational bounds on the PBH abundances from the LIGO-Virgo-Collaboration O3 data.

关键词： AdS/QCD confinement/deconfinement phase transition gravitational wave primordial black hole

Primordial black holes and curvature perturbations from false vacuum islands

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Science China(Physics,Mechanics & Astronomy) 2024年第9期67卷 58-72页

作者： Rong-Gen Cai Yu-Shi Hao shao-jiang wang School of Physical Science and Technology Ningbo UniversityNingbo 315211China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Asia Pacific Center for Theoretical Physics Pohang 37673Republic of Korea

Recently,much attention has been focused on the false vacuum islands that are flooded by an expanding ocean of true-vacuum bubbles slightly later than most of the other parts of the *** delayed decay regions will accumulate locally larger vacuum energy density by staying in the false vacuum longer than those already transited into the true vacuum.A false vacuum island with thus acquired density contrast of a super-horizon size will evolve locally from radiation dominance to vacuum dominance,creating a local baby Universe that can be regarded effectively as a local closed *** such density contrasts of super-horizon sizes can ever grow large enough to exceed the threshold of gravitational collapse,primordial black holes will form similar to those collapsing curvature perturbations on super-horizon scales induced by small-scale enhancements during *** not,such density contrasts can still induce curvature perturbations potentially observable *** this paper,we revisit and elaborate on the generations of primordial black holes and curvature perturbations from delayed-decayed false vacuum islands during asynchronous first-order phase transitions with fitting formulas convenient for future model-independent studies.

关键词： first-order phase transitions primordial black holes curvature perturbations

Cosmic inflation from broken conformal symmetry

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Communications in Theoretical Physics 2022年第9期74卷 120-130页

作者： Rong-Gen Cai Yu-Shi Hao shao-jiang wang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced Study(HIAS)University of Chinese Academy of Sciences(UCAS)Hangzhou 310024China School of Physical Sciences University of Chinese Academy of Sciences(UCAS)Beijing 100049China

A period of rapidly accelerating expansion is expected in the early Universe implemented by a scalar field slowly rolling down along an asymptotically flat potential preferred by the current *** this paper,we point out that this picture of the cosmic inflation with an asymptotically flat potential could emerge from the Palatini quadratic gravity by adding the matter field in such a way to break the local gauged conformal symmetry in both kinetic and potential terms.

关键词： Palatini gravity modified gravity conformal symmetry cosmic inflation

The gravitational-wave physics

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National Science Review 2017年第5期4卷 687-706页

作者： Rong-Gen Cai Zhoujian Cao Zong-Kuan Guo shao-jiang wang Tao Yang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of Sciences School of Astronomy and Space Science University of Chinese Academy of Sciences Department of Astronomy Beijing Normal University School of Physical Sciences University of Chinese Academy of Sciences Institute of Applied Mathematics Academy of Mathematics and Systems ScienceChinese Academy of Sciences

The direct detection of gravitational wave by Laser Interferometer Gravitational-Wave Observatory indicates the coming of the era of gravitational-wave astronomy and gravitational-wave cosmology. It is expected that more and more gravitational-wave events will be detected by currently existing and planned gravitational-wave detectors. The gravitational waves open a new window to explore the Universe and various mysteries will be disclosed through the gravitational-wave detection, combined with other cosmological probes. The gravitational-wave physics is not only related to gravitation theory, but also is closely tied to fundamental physics, cosmology and astrophysics. In this review article, three kinds of sources of gravitational waves and relevant physics will be discussed, namely gravitational waves produced during the inflation and preheating phases of the Universe, the gravitational waves produced during the first-order phase transition as the Universe cools down and the gravitational waves from the three phases:inspiral, merger and ringdown of a compact binary system, respectively. We will also discuss the gravitational waves as a standard siren to explore the evolution of the Universe.

关键词： gravitational waves inflation reheating first order phase transition binary black holes standard siren

GWs from S-stars Revolving Around SMBH at Sgr A

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Communications in Theoretical Physics 2018年第12期69卷 735-748页

作者： Rong-Gen Cai Tong-Bo Liu shao-jiang wang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of Sciences School of Physical Sciences University of Chinese Academy of Sciences

A preliminary estimation of gravitational waves(GWs) from the extreme-mass-ratio-inspirals(EMRIs)system in the Galactic Centre(GC) is given for the 37 observed S-stars revolving around the supermassive black hole(SMBH) at Sagittarius(Sgr) A*. Within this century, the total strain of the gravitational waveform calculated from the post-Newtonian(PN) method with eccentricity is well below the current planned sensitivity of pulsar-timing-array(PTA). New technology might be required in order to extract GW signal from this EMRIs system for future PTA detections.

关键词： gravitational waves extreme-mass-ratio-inspirals supermassive black hole

The Gravitational-wave physics Ⅱ: Progress

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Science China(Physics,Mechanics & Astronomy) 2021年第12期64卷 18-67页

作者： Ligong Bian Rong-Gen Cai Shuo Cao Zhoujian Cao He Gao Zong-Kuan Guo Kejia Lee Di Li Jing Liu Youjun Lu Shi Pi Jian-Min wang shao-jiang wang Yan wang Tao Yang Xing-Yu Yang Shenghua Yu Xin Zhang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China Department of Astronomy Beijing Normal UniversityBeijing 100875China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100080China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China Key Laboratory for Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced Study(HIAS)University of Chinese Academy of SciencesHangzhou 310024China MOE Key Laboratory of Fundamental Physical Quantities Measurements Hubei Key Laboratory of Gravitation and Quantum PhysicsNational Precise Gravity Measurement Facility(PGMF)Department of Astronomy and School of PhysicsHuazhong University of Science and TechnologyWuhan 430074China Asia Pacific Center for Theoretical Physics Pohang 37673Korea Department of Physics College of SciencesNortheastern UniversityShenyang 110819China Key Laboratory of Data Analytics and Optimization for Smart Industry(Northeastern University) Ministry of EducationShenyang 110819China Department of Physics Chongqing UniversityChongqing 401331China

It has been a half-decade since the first direct detection of gravitational waves, which signifies the coming of the era of the gravitational-wave astronomy and gravitational-wave cosmology. The increasing number of the detected gravitational-wave events has revealed the promising capability of constraining various aspects of cosmology, astronomy, and gravity. Due to the limited space in this review article, we will briefly summarize the recent progress over the past five years, but with a special focus on some of our own work for the Key Project "Physics associated with the gravitational waves" supported by the National Natural Science Foundation of China. In particular,(1) we have presented the mechanism of the gravitational-wave production during some physical processes of the early Universe, such as inflation, preheating and phase transition, and the cosmological implications of gravitational-wave measurements;(2) we have put constraints on the neutron star maximum mass according to GW170817 observations;(3) we have developed a numerical relativity algorithm based on the finite element method and a waveform model for the binary black hole coalescence along an eccentric orbit.

关键词： gravitational wave gravitational-wave cosmology gravitational-wave astronomy numerical relativity

Sequential Fluorescent Labeling Observation of Maxillary Sinus Augmentation by a Tissue-engineered Bone Complex in Canine Model

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International Journal of Oral Science 2009年第1期1卷 39-46页

作者： Xin-quan jiang shao-yi wang Jun Zhao Xiu-li Zhang Zhi-yuan Zhang Shanghai Research Institute of Stomatology Shanghai Key Laboratory of Stomatolgoy Shanghai Ninth People＇s Hospitalaffiliated to Shanghai Jiao Tong University School of Medicine Shanghai China

Aim To evaluate the effects of maxillary sinus floor elevation by a tissue-engineered bone complex of β-tricalcium phosphate （β-TCP） and autologous osteoblasts in dogs. Methodology Autologous osteoblasts from adult Beagle dogs were cultured in vitro. They were further combined with β-TCP to construct the tissue-engineered bone complex. 12 cases of maxillary sinus floor elevation surgery were made bilaterally in 6 animals and randomly repaired with the following 3 groups of materials： Group A （osteoblasts/D-TCP）; Group B （β-TCP）; Group C （autogenous bone）（n=4 per group）. A polychrome sequential fluorescent labeling was performed post-operatively and the animals were sacrificed 24 weeks after operation for histological observation.Results Our results showed that autologous osteoblasts were successfully expanded and the osteoblastic phenol- types were confirmed by ALP and Alizarin red staining. The cells could attach and proliferate well on the surface of the ~3-TCP scaffold. The fluorescent and histological observation showed that the tissue-engineered bone complex had an earlier mineralization and more bone formation inside the scaffold than β-TCP along or even autologous bone. It had also maximally maintained the elevated sinus height than both control groups. Conclusion Porous 13-TCP has served as a good scaffold for autologous osteoblasts seeding. The tissue-engineered bone complex with β-TCP and autologous osteoblasts might be a better alternative to autologous bone for the clinical edentulous maxillary sinus augmentation.

关键词： maxillary sinus augmentation tissue engi-neering β-tricalcium phosphate osteoblasts fluorescentlabeling