February 26 marks the first day of UCASers’ spring semester in 2024. After a brief break for the Spring Festival, ICTP-APers have gone back to school for a new semester. During the winter vocation, teachers and students have captured the beautiful scenery with their lenses and now let's take a look at their spectacular shootings. From this photo, we can see that the tree is decorated with many red lanterns because it is a custom for Chinese to adorn their doors with red couplets and colorful lantersn to enrich the festival asmosphere. This group of photo displays the beautiful scenery after snow.These two photos were taken in Macau and HK respectively, the first one is the fireworks set to celebrate the Chinese New Year and the second one is the Ferris Wheel featured by four Chinese characters “Long Lai Yun Zhuan”, which means that luck comes to you as the Year of the Dragon approaches.This photo is taken at the front gate of the Old Summer Palace, which is also known as “Yuanmingyuan”This photo is taken in Guangzhou.The Spring Festival is one of the most significant traditional celebrations in Chinese culture, marking a momentous occasion for family gatherings and shared joy. The year of 2024 is also the Year of the Dragon or Loong, therefore, the dragon rightfully takes center stage. Now, let us warmly welcome the auspicious dragon and together create a symphony of happiness for the new year.Home is where the heart is. In the 2024 Spring Festival, ICTP-APers scattered across the country, yet their hearts and hands are still connected. This traditional holiday of bidding farewell to the old and welcoming the new has become a collective journey that fosters a sense of belonging, fulfillment, and happiness among the ICTP-AP community. Amidst the warmth and nostalgia, it adds new meaning and responsibility to the Dragon Year's new spring, making everyone’s heart warmer, bringing students and faculty closer, and strengthening their love for UCAS. Editor: Le Zhang, Min ZhangPhotographers: Fanzi Meng, Le Zhang, Min Zhang, Qimin Song
The 2023 Winter School on Frontier and Interdisciplinary Sciences was held from 14th January to 20th January in Yunnan Province. It was organized by the International College and the International Centre for Theoretical Physics-Asia-Pacific, and hosted by Kunming Institute of Zoology, Kunming Institute of Botany and Xishuangbanna Tropical Botanical Garden of CAS. Over 60 students from different institutes of CAS participated in the 6-day activity. A Journey of Interdisciplinary SciencesDuring the winter school, we have invited experts and professors from different fields, including botany, zoology, ecology, microbiology, environmental science, biochemistry and molecular biology, medicinal chemistry, pharmacology, bioinformatics, cell biology and genetics, so as to encourage students to engage in interdisciplinary scientific research and innovative exploration across different disciplines.We have also invited a professor from the Foreign Language School of Yunnan University to deliver a report on China’s national condition, enabling a valuable opportunity for international students to have a glimpse of the history, culture, music and development of China. A Journey of LifeAs one of a few areas that have tropical forests at about 20 degrees North latitude, Yunnan province is well-known for its plant diversity. Thanks to its various geographic features, Yunnan is also rich in animal resources. During this winter school, we have also arranged a field study in Fu Li Palace Greenhouses and Tea Garden at Kunming Institute of Botany, the Kunming Natural History Museum of Zoology and Xishuangbanna Tropical Forest Garden. Students were impressed by the biodiversity of Yunnan and learned a lot about the animal and plant species in those gardens and museums, inspiring them to carry out cross-disciplinary scientific research and value the importance of biodiversity to sustainable development. A Journey of CultureDuring the 6-day school, we have also brought the international students to the memorial hall of the National Southwest Associated University (SWAU). Built in Kunming during the War of Resistance against Japanese Aggression, SWAU represented a merger of Peking University, Tsinghua University, and Nankai University as a comprehensive university. Over its eight-year tenure, the university was a gathering place of accomplished masters and renowned scholars, including Chen-Ning Yang and Tsung-Dao Lee.Walking on the quiet campus, students and teachers travelled back to the time when the students had to read in the tea house and worked hard to strive for the country’s development. Another meaningful trip took place in a socialist new village--Chengzi Village in Menglun County, Xishuangbanna. Guided by a local villager, we went into the small village, which has about 300 households. The buildings are all traditional Dai-style. Yet, instead of rammed earth and thatch, the buildings are all made of cement and bricks, which are more solid and water-proof.International students were surprised by China’s rural development and one student from Tajikistan noticed that many households have stuck the photos of President Xi on the walls and asked why. “That is because the houses used to be decrepit and Chinese government started to help them restore their houses and explore local tourism resources and bring in innovative ways to increase the income of local residents since 2012”, answered Ms Zhang, from ICTP-AP. Then she pointed at the QR-code hung up on the fruit trees grown on the side of the path and explained that visitors can pick the fruit from the tree and pay by scanning the QR-code without talking to the owner. When we came to a local household, we were invited to make local snacks with the Dai people. Students enjoyed themselves and deeply experienced China’s cultural diversity and ethnic harmony and unity. After the six-day learning and experiencing, the international students have broadened their horizons and strengthened their friendship with students from different institutes. They have also learnt more about China’s national condition and cultural diversity.
The International Centre for Theoretical Physics Asia-Pacific held the annual conference in Beijing from 25th to 26th November, 2023. The International Governing Board of ICTP-AP was held at the University of Chinese Academy of Sciences (UCAS) on the morning of 25th November and the director of the Bureau of Frontier Sciences and Education, CAS, Su Gang attended the conference and delivered an opening remark on behalf of Chang Jin, the President of the International Governing Board of ICTP-AP. Director Su Gang extended a warm welcome to the participants and introduced the outcomes and progress that CAS has achieved in the area of basic sciences and international exchanges and cooperation. He also emphasized that we should leverage the role that ICTP-AP has played as an international organization to promote the internationalization of CAS and expand the international influence of CAS, enhance basic research, and take a lead in international science and technology highlands.Wei-Dong Liu, director of the Bureau of International Cooperation of CAS and General Secretary of the International Governing Board, Professor Fernando Quevedo, the president of the International Science Council of ICTP-AP, Professor Ralf Kaiser, the senior coordinator of ICTP and Dr. Li Li, the senior project consultant for natural science of UNESCO in Beijing Office, the vice director of the National Natural Science Foundation of China(NSFC), Yong-Tao Zhang, Vice President of UCAS, Guo-Qiang Yang, and the director of ICTP-AP, vice academic president of UCAS, Professor Yue-Liang, Wu and representatives from the governing board attended the conference. We also invited the director of International Affairs Office of UCAS, Yong Xie and vice director of ICTP-AP, Song He to attend the conference as observers. Director Wei-Dong Liu hosted the conference and said that CAS will continue to carry out international talent exchanges, strengthen international cooperation in frontiers cross-disciplinary and large science equipment and organize activities, such as Science and Technology Training Class for BRI and Developing Countries. Vice director Yong-Tao Zhang said that NSFC is planning to set up a special division that focuses on international cooperation so as to support international organizations such as ICTP-AP and more young foreign scholars and talents to come to China to carry out scientific research and cooperation. Dr. Li Li mentioned that UNESCO is dedicated to promoting academic activities to primary and middle school students and college students in the Asia-Pacific region, and hopes that ICTP-AP would join the activity and contribute to the SDGs. The IGB deliberated on the progress report of ICTP-AP from 2019 to 2023 and its middle and long-term development plan, discussed on issues, including cooperation and exchange, talent cultivation and platform establishment, etc. The governing board also advised on the new members of the ISC and showed support towards the cooperation and exchanges of ICTP-AP at home and abroad as well as its establishment of ICTP-AP branches.The International Science Council was held on the evening of 25th November, 12 ISC members participated in the conference online or offline. Director of ICTP-AP gave a report on the scientific research progress, international and domestic academic exchanges, talent recruitment and cultivation, outreach activities of ICTP-AP. During the conference, Professor Zi-Ren Luo also introduced the latest progress of Taiji Laboratory, which is established under the support of ICTP-AP and Professor Chao-Qiang Geng talked about the School of Fundamental Physics and Mathematics of Hangzhou Institute for Advanced Study (HIAS) of UCAS. Members of ISC had an in-depth discussion on the report of ICTP-AP and its development plan for the next stage and they gave many suggestions on the research direction and international cooperation as well as talent cultivation. Members of ISC also nominated the new members for ISC.ICTP-AP has held the Forum on Fundamental Physics in Yanqi Lake Campus on 26th November. Professor Fernando Quevedo, president of the ISC of ICTP-AP and Professor Kimyeong Lee, vice president of KIAS, Professor Poul Henrik Damgaard, founding and current director of Niels Bohr International Academy, and Professor Yue-Liang Wu, director of ICTP-AP have given keynote speeches. Eight young teachers from ICTP-AP and School of Fundamental Physics and Mathematics of HIAS have given academic reports on the forum. The foreign guests also visited the Yanqi Lake Campus and School History Museum during the meeting to learn more about the development history and vision of UCAS.
The last sub-forum of the Frontiers on Quanta-Cosmos Physics Forum has been successfully held in Nanjing University (Suzhou Campus) on October 24th, 2023. This event is one of the China’s IYBSSD serial activity, and it’s themed on Fundamental Physics and Quantum Century, hosted by ICTP-AP, ITP CAS, HIAS and Nanjing University. CAS academician Yue-Liang Wu, director of ICTP-AP and academic vice president of UCAS, has been devoted to the research in basic theories in gravity and hyper unified field theory. He borrowed this opportunity to send his recent publication Foundations of the Hyper-unified Field Theory to his alma mater Nanjing University. Professor Wu said that this book is the fruit of his scientific career over the past four decades after his graduation and he is very glad to express his gratitude to his alma mater with his most satisfying research outcome for the cultivation of Nanjing University.The forum is hosted by Professor Yongliang Ma from Nanjing University and Jinyan Liu from the Institute for the History of Natural Sciences, CAS. Director of the research centre for the history of science and technology from Nankai University Baichun Zhang, Professor Shiyu from University of Chinese Science and Technology, Professor Hui Liu, Vice President of the School of Physics from Nanjing University, and CAS academician Yueliang Wu from UCAS have delivered wonderful and insightful speeches at the forum, attracting thousands of viewers online and offline. At the closing ceremony, director of the ICTP-AP office, Dr. Min Zhang gave a speech to make an overview of this activity. This sub-forum marked the closure of the IYBSSD2022-2023 activity in China since its beginning in June, 2022. Over the past years, ICTP-AP has worked with Shandong University, Hunan University, Nanjing University and other partner institutes to organize and host a total of six sub forums, inviting 30 scientists to discuss on frontiers of basic science and human development. This activity has attracted 1.5 million people online and offline.
The 2023 Track and Field Sports Game was held on October 13th to 14th,2023. The opening ceremony was held on the morning of 13th October and 44 square teams composed of the students and faculty of different departments and schools of UCAS presented their performances on the playground. This year, ICTP-AP made its debut at the opening ceremony with 15 faculty including professors, postdocs and administrative staff and 20 students walking in the square team. On the morning of 13th October, women's100 meter, women's 400 meter final and long jump was held. Athletes of ICTP-AP spared no effort in their games and has won prizes for the center. Dr. Yinghui Liu has won the third prize in long jump and postfoc Shuang Wang has won the champion of the 100 final, breaking the record of UCAS and Dr. Haihong Jia ranked the eighth in the long jump. What’s more, the student of ICTP-AP, Qiyan Zhang has won the champion of the 400 meters final and broke the record of UCAS. Shuang WangQiyan ZhangYinghui Liu(on the right)Haihong JiaIn the afternoon, an unexpected hailstone fall interrupted the game and the events were postponed to the night. On the second day of the game, the famous sports commentator Qiaosheng Han, a famous sports commentator was invited to the campus and broadcasted the game live and cheered for the athletes. The men’s 4×100 meters relay was held on the morning of 14th October and students team from ICTP-AP ranked the sixth. Qiaosheng Han(from the left to the right) Manjia Liang, Yuchen Zhou, Chong Lei, Yuanjie Li, Qimin Song
To celebrate the Mid-Autumn Festival, ICTP-AP has held a gathering party at Zhongguancun Campus, over thirty students signed up for the event and actively took part in this activity. ICTP-AP has prepared many delicate gifts for the participants, including small pouch filled with sweet Osmanthus flowers. To warm up the atmosphere, we also prepared a dozen of English and Chines riddles for the guests to solve. It’s a tradition for people to solve the riddles during Chinese festivals. When the participants are immersed in the joy of solving riddles, we handed out each participant a set of materials for painting plaster rabbit statues. Rabbit God, Tu’erye in Chinese, is a deity of Chinese folk religion unique to Beijing, where his sculptures are traditionally crafted. The fairytale rabbit descended to a plague-stricken world and healed people. For his good deed, he is commemorated with a lovely image and receive thanks every year. Therefore, worshipping Lord Rabbit has become a typical custom observed in Beijing. After hearing the story, the participants couldn’t wait to start their painting. After their brain-storming imagination, dozens of the plaster sculptures were vividly presented. Another tradition of Mid-Autumn Festival is eating mooncakes. Today, participants got the opportunity to make mooncakes by themselves. This activity helped the international students better understand Chinese traditional culture and they all felt very relaxed during the whole process, which gave them a break from the digital world and travelled back to thousand years ago to experience the romance of ancient Chinese people. Students from ICTP-AP also enjoyed this activity and they felt more connected to each other after the celebration party.
On July 3，2023 the closing ceremony of the 2023 ICTP-AP Summer School was held successfully on Zhongguancun Campus of the University of Chinese Academy of Sciences(UCAS), marking the end of this year’s summer school.On the closing ceremony, faculty including professor representatives, administrative staff and postdoc representative all showed up, with a student representative pre-recorded video being shown on the stage. At the very beginning of the ceremony, Dr. Min Zhang showed a video that recorded students’ activities over the past three days, from the opening ceremony on the evening of June 30 to the last day’s visit on Yanqi Campus. On the first two days, students enjoyed an academic feast characterized by 10 lectures given by professors of UCAS, including a CAS academician, Professor Yue-Liang Wu, who is also the director of the ICTP-AP. Lecture given by CAS academician Yue-Liang Wu via videoThese two days also witnessed heated discussions between teachers and students, which inspired the students and provided a valuable experience for them to talk to the distinguished professors and peers from across the country face to face. At the end of the video was their last day’s visits to places including the Museum of Chinese Academy of Sciences and Two Bombs and One Satellite, the history Museum of UCAS on Yanqi Lake Campus of UCAS, which helps the students better understand the “huge campus” atmosphere and the history and development of UCAS. Students at the Museum of CAS and Two Bombs and One SatelliteStudents at the History Museum of UCASAfter a brief break on the campus, students then visited the National Space Science Center (NSSC) and went to the lab of the Institute of Mechanics,CAS. This special experience allowed Students to learn more about our country’s rapid development in space science and knew more about the significance of gravitational wave exploration. Students going into the Lab of the Institute of Mechanics, CASAfter watching the video, Professor Jun Zhang, as the professor representative of ICTP-AP, delivered a brief speech to the students and extended warm thanks to all the participants and organizers of this event. And then, Yuxin Liu, a doctoral student of ICTP-AP who is currently exchanging abroad, shared his experience about the advantages of studying in UCAS and how grateful he is as a student of ICTP-AP. He also encouraged the fellow students to work hard and pursue their dream in scientific studies and research.To help the students to learn more about Taiji Space Program, the post-doctoral He Wang also gave a brief introduction of his scientific work at ICTP-AP. After Dr. Wang’s speech comes the most unique and interesting part of the ceremony. Students who have been divided into four groups on the opening ceremony gave vivid and elaborate preseantations on their topics. Professors present said that the students have done a great job, and they also commented on their reports and shared their own insights respectively, which helped students to learn the strengths and shortcomings of their own work. Professor Tian commented that this is the most special and unique closing ceremony of summer school that he has ever been to, which is a huge encouragement to all the participants of this event. Closing CeremonyAfter the professors’ hard-hitting and professional comments, two groups won the prizes, which are the cultural and creative souvenirs of ICTP-AP, for their excellent group performance. Dr Min said that this is to encourage students to work hard and value the spirits of team work. Then comes to the most exciting part that the students are waiting for, that is to reveal the final 19 Students of Excellence.With the end of the closing ceremony, this year’s ICTP-AP summer school also came to a period, yet this special memory during the past four days will be carried by every participant. It provided students from universities across the country with a great opportunity to know about each other, talk with each other and most importantly, to have academic exchanges with the professors in the field of the advanced scientific research and to experience the study and life at ICTP-AP, UCAS in an immersive way.
The Asia-Pacific School and Workshop on Gravitation and Cosmology (APSW-GC) has been held in the “Eco·Economy” Senior Talent Hub by the side of beautiful Qiandao Lake in Chun’an County, Hangzhou from May 14 to May 22, 2023. This 9-day long school is organized by the International Center for Theoretical Physics (ICTP-AP) and co-hosted by the Asia-Pacific Center for Theoretical Physics (APCTP), Hangzhou Institute for Advanced Study of UCAS, Institute of Theoretical Physics of CAS, National Astronomical Observatories, CAS and Zhejiang University of Technology.What’s worth mentioning is that there were over ten invited foreign physicists coming from afar and giving lectures on gravity cosmology, including gravitational wave and basic physics, black hole physics, dark matter and dark energy, inflation and cosmology. This event also provided a platform for the experts and scholars from China and overseas to exchange their academic ideas with each other so as to promote the academic cooperation among scientists and the training of graduate and doctoral students in the Asia-Pacific Region in the field of gravitation and cosmology. The APSW-GC 2023 was held in the “Eco·Economy” Senior Talent Hub by the side of beautiful Qiandao Lake and participants all enjoyed the pleasant environment and cultural atmosphere of the place. Professor Robert Mann from University of Waterloo in Canada and Professor Sang Pyo Kim from Kunsan Naional University in South Korea who came to the Chun’an county for the first time, said that “we didn’t feel any foreignness here, yet we felt comfortable and relaxed, just like at home. We could breathe the wild nature and it’s really suitable for academic research here”. It is believed that this school and workshop will continue to strengthen the cooperation and exchange between the ICTP-AP and distinguished universities across the world and expand its international influence.
Various observations from particle physics, astrophysics, and cosmology have suggested that the standard model of particle physics for describing the microscopic structure of matter is not complete. It is then one of the vital scientific problems of current particle physics and cosmological observations to search for the signals of new physics beyond the standard model of particle physics. Many new physics models beyond the standard model of particle physics predict the cosmological first-order phase transitions during the evolution of our Universe. With the temperature decreasing due to the expansion of the Universe, symmetries at high energy scales would be broken simultaneously, and the associated quantum field would decay into the true vacuum from the false vacuum by quantum tunneling via the nucleation and expansion of true-vacuum bubbles, resulting in the energy transfer into the kinetic energy of bubble walls and background fluid, similar to the violent process of frozen ice from supercooling water. The following collisions among expanding bubbles would induce large fluctuations in the energy density. Therefore, as a violent process in the early Universe, the cosmological first-order phase transitions could produce various observational effects, including the stochastic gravitational wave background, primordial magnetic field, and baryon asymmetry, making it feasible to probe or constrain the new physics from astrophysical and cosmological observations. The gravitational-wave observation from cosmological first-order phase transition is also one of the main scientific targets of many gravitational-wave observational projects.Recently, the postdoc Dr. Jing Liu from the International Centre for Theoretical Physics Asia-Pacific of the University of Chinese Academy of Sciences, the associate researcher Prof. Ligong Bian from Chongqing University, the researchers Prof. Rong-Gen Cai, Prof. Zong-Kuan Guo, and the postdoc Dr. Shao-Jiang Wang from the Institute of Theoretical Physics of Chinese Academy of Sciences have proposed a new mechanism for the productions of primordial black holes, and given rise to rigorous constraints on the properties of cosmological first-order phase transitions from the astrophysical observational data. Due to the randomness of quantum tunneling, the progress of vacuum decay varies in different regions. Note that the false vacuum energy density barely changes with the cosmological expansion, while the energy densities of other matter components like radiations and cold dark matter are rapidly diluted with the expansion of the Universe. Therefore, the regions of vacuum decay that fall behind the others would admit higher energy densities after the phase transition. This is to say that the cosmological first-order phase transition would induce fluctuations in energy density. These high-energy-density regions would eventually produce primordial black holes via gravitational collapse, and these primordial black holes are almost monochromatic in their mass spectrum. The relevant paper has been published as a Letter in Phys. Rev.D 105 (2022) L021303. The primordial black holes produced with this mechanism and the associated gravitational waves could explain the merger rate of black hole binaries observed in LIGO-Virgo collaborations as well as the signal from the NANOGrav observation.They also discovered that the first-order phase transition could induce superhorizon curvature perturbations, and in turn probe and constrain the phase-transition properties from the observations of the curvature perturbations at small cosmological scales. The nucleation rate of true vacuum bubbles per unit time and per unit volume could be obtained from the quantum tunneling. After the phase transition, the regions with a scale larger than the product of phase-transition duration and light speed share no causal connection, and the causality requires the energy density spectrum of curvature perturbations to be proportional to the cube of wavenumber. Hence, if the superhorizon scale is considered, the induced curvature perturbations from phase transitions could largely surpass the primordial perturbations from the early-universe inflation so that it can be probed by various astrophysical observations, including the temperature anisotropies and spectrum distortion in the cosmic microwave background radiations and the number density in ultra-compact minihalos. In turn, we could also constrain the phase-transition properties via the upper bounds on the curvature perturbations from these astrophysical observations.Figure 1: Constraints on the parameter space of phase transition from different observations on the curvature perturbations, where alpha denotes the phase-transition strength, beta/H_* denotes the phase-transition rate, and T_* is the phase-transition temperature. The gray solid curves and gray dotted curves in the left and middle panels are constraints from the gravitational-wave background and big bang nucleosynthesis, respectively.They have obtained the power spectrum of the curvature perturbations induced from the first-order phase transitions, and for the first time given rise to rigorous constraints on the phase-transition parameters from the upper bounds on the curvature perturbations from astrophysical observations. The relevant paper has been published in Phys. Rev. Lett 130 (2023) 051001. As shown in Figure 1, all constraints on the cosmological first-order phase transitions below the electroweak scale are obtained from the upper bounds on the curvature perturbations from the big bang nucleosynthesis (blue curves), the temperature anisotropies and spectrum distortion in the cosmic microwave background radiations (green curves), and the number density in ultra-compact minihalos (orange solid curves from pulsar timing array and orange dashed curves from Gamma-ray detections). This study largely enhances the previous constraints from the stochastic gravitational-wave background (gray solid curves) and big bang nucleosynthesis (gray dotted curves) on the QCD first-order phase transition, low-energy dark-sector first-order phase transition, and some of the electroweak first-order phase transition, in particular the low-energy transitions and slow first-order phase transitions.This study is supported by relevant projects from the National Natural Science Foundation of China, the Ministry of Science and Technology of China, and the Chinese Academy of Sciences.Link: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.130.051001Contact:Jing Liu: liujing@ucas.ac.cnInternational Centre for Theoretical Physics Asia-Pacific
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