Shanghai Jiao Tong University Physics and Astronomy Academic Innovation Forum for Doctoral Students
Tsung-Dao Lee Institute
The “Lun Dao” Academic Innovation Forum 2021 for Doctoral Students will take place during December 10-12, 2021, at Tsung-Dao Lee Institute, Shanghai, China. The Forum is held by TDLI, and co-organized by School of Physics and Astronomy, Shanghai Jiao Tong University. The scope of the forum will be on basic quantum physics, particle physics, and astronomy. Doctoral students in physics and astronomy disciplines from well-known universities are invited to attend.
Scholars from leading universities and research institutes at home and abroad will share their latest achievements, while doctoral students are particularly encouraged to present their research work through posters or oral reports. Outstanding posters and oral reports will receive an award certificate with the signature of Frank Wilczek, Director of TDLI and a Nobel Prize laureate in physics.
The purpose of this forum is to provide a platform to further academic exchanges between physics and astronomy disciplines of different universities, and deepen students understanding on academic frontier, broaden their academic horizons, and stimulate their academic innovation.
The forum is complimentary to attend, and free lunch will be included with registration.
This website is for Registration and Submitting Materials.
For more information about this forum, Please visit https://tdli.sjtu.edu.cn/CN/events/941
bingzhi li
Chun Huang
Danning Liu
Danying Yu
Fei He
Guan-Wen Yuan
Guangxuan Lan
Han Xiao
Jia-Zheng Ma
Jiahao Yang
Jiming Yu
Lei Zu
Lining Mao
Min-Huan Chu
Qibin LIU
Qing Li
Qiu-Ping Shen
Rui Niu
Shaofeng Duan
Siyuan Wan
TianLe Zhao
Tianye Xia
Weitao Lv
Weiwei Zhao
Wenke Ren
Xiangke Zhang
Xiao Wang
Xiaoxiang Zhou
Xiaoyu Chen
Xiaoyu Wang
Xuan Yang
Yanfeng Hang
Yanjie Zeng
Yaoyao Zong
Ying Xiang
Yu Liu
Yuanyuan Yang
Yuchen Ding
Yunfeng Wei
Zeyang Sun
Zhen Wang
Zhou Huang
世聪 胡
子文 张
进 孙
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Opening Session: TDLI(Zhang Jiang)
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Coffee Break
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Astro Session I
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1
81 New Candidate Fast Radio Bursts in Parkes Archive
We have searched for weak fast radio burst (FRB) events using a database containing 568,736,756 transient events detected using the Parkes radio telescope between 1997 and 2001. In order to classify these pulses, and to identify likely FRB candidates, we used a machine learning algorithm based on ResNet. We identified 81 new candidate FRBs and provide details of their positions, event times, and dispersion measures. These events were detected in only one beam of the Parkes multibeam receiver. We used a relatively low S/N cutoff threshold when selecting these bursts and some have dispersion measures only slightly exceeding the expected Galactic contribution. We therefore present these candidate FRBs as a guide for follow-up observations in the search for repeating FRBs.
Speaker: Xuan Yang (purple mountain observatory) -
2
Blob formation and ejection from the radiative inefficient accretion flow around massive black hole
We study the small scale magnetic reconnection above the radiative inefficient accretion flow around massive black hole via 2D magnetohydrodynamics (MHD) numerical simulation, in order to model the blob formation and ejection from the accretion flow around Sgr A*. The connection of both the newly emerging magnetic field and the pre-existing magnetic field is investigated to check whether blobs could be driven in the environment of black hole accretion disc. After the magnetic connection, both the velocity and temperature of the plasma can be comparable to the inferred physical properties at the base of the observed blob ejection. For illustration, three small boxes which are located within 40 Schwarzschild radii from the central black hole are chosen as our simulation areas. At the beginning of the reconnections, the fluid is pulled toward the central black hole due to the gravitational attraction and the current sheet produced by the reconnection is also pulled toward the same direction, consequently, the resulting outflows move both upwards and towards the symmetry axis of the central black hole. Eventually, huge blobs appear, which supports the catastrophe model of episodic jets (Yuan et al. 2009a). It is also found that the closer to the black hole the magnetic connection happens, the higher the converting efficiency of the magnetic energy into the heat and kinetic energy. For these inner blobs, they have vortex structure due to the Kelvin–Helmholtz instability, which happens along the current sheet separating the fluids with different speed.
Speaker: TianLe Zhao (University of Science and Technology of China) -
3
The luminosity and redshift distributions of long gamma-ray bursts
Gamma-ray bursts (GRBs) are the most luminous explosive transients in the cosmos. Generally, long GRBs (LGRBs) with durations $T_{90}$>2s are believed to be powered by the core collapse of massive stars then thus suggested to be excellent tools to probe the star formation rate (SFR) at high redshifts. However, base on the studies over the last two decades, there is a general agreement on the fact that GRBs may have experienced some kind of evolution with redshift. It should be emphasized that the evolution features of GRBs are inferred from the statistics of the observational samples. However, as is well known, the observational samples inevitably subject to various instrumental selection effects and observational biases e.g. trigger problems of faint bursts and redshift-measurement problems for hard location and limited ability of instrument. It is difficult to reveal the intrinsic distributions of long GRBs and their evolution features from these samples. Though some complete samples can provide a solid basis for the statistical study of the long-GRB population, their current sample size is admittedly small. In this work, we update and enlarge the GRB sample observed by Swift/BAT and use it to revisit the GRB luminosity function (LF) and redshift distribution by carefully considering the incomplete sampling of the faint bursts and the probability of redshift measurement.
Speaker: Ms Guangxuan Lan (PMO) -
4
Cross-correlation of Planck CMB lensing with DESI galaxy groups
We measure the cross-correlation between galaxy groups constructed from DESI Legacy Imaging Survey DR8 (Yang et al. 2021) and Planck CMB lensing, over overlapping sky area of 16876 deg2. The detections are significant and consistent with the expected signal of the large scale structure of the universe, over group samples of various redshift, mass and richness Ng and over various scale cuts. The overall S/N is 39 for a conservative sample with Ng ≥ 5, and increases to 48 for the sample with Ng ≥ 2. Adopting the Planck 2018 cosmology, we constrain the density bias of groups with Ng ≥ 5 as 1g = 1.31 ± 0.10, 2.22 ± 0.10, 3.52 ± 0.20 at 0.1 < I ≤ 0.33, 0.33 < I ≤ 0.67, 0.67 < I ≤ 1 respectively. The value-added group catalog allows us to detect the dependence of bias on group mass with high significance. It also allows us to compare the measured bias with the theoretically predicted one using the estimated group mass. We find excellent agreement for the two high redshift bins. However, it is lower than the theory by ∼ 3σ for the lowest redshift bin. Another interesting finding is the significant impact of the thermal Sunyaev Zel’dovich (tSZ). It contaminates the galaxy group-CMB lensing cross-correlation at ∼ 30% level, and must be deprojected first in CMB lensing reconstruction.
Speaker: Ms Zeyang Sun (SJTU) -
5
BIASED TRACER RECONSTRUCTION WITH HALO MASS INFORMATION
Plenty of crucial information about our Universe is encoded in the cosmic large-scale structure (LSS). However, the extractions of these information are usually hindered by the nonlinearities of the LSS, which can be largely alleviated by various techniques known as the reconstruction. In realistic applications, the efficiencies of these methods are always degraded by many limiting factors, a quite important one being the shot noise induced by the finite number density of biased matter tracers (i.e., luminous galaxies or dark matter halos) in observations. In this work, we explore the gains of biased tracer reconstruction achieved from halo mass information, which can suppress shot noise component and dramatically improves the cross-correlation between tracer field and dark matter. To this end, we first closely study the clustering biases and the stochasticity properties of halo fields with various number densities under different weighting schemes, i.e., the uniform, mass and optimal weightings. Then, we apply the biased tracer reconstruction method to these different weighted halo fields and investigate how linear bias and observational mass scatter affect the reconstruction performance. Our results demonstrate that halo masses are critical information for significantly improving the performance of biased tracer reconstruction, indicating a great application potential for substantially promoting the precision of cosmological measurements [especially for baryon acoustic oscillations (BAO)] in the ambitious on-going and future galaxy surveys.
Speaker: Mr Yu Liu (Department of Astronomy, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai)
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1
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Lunch&&Break
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Astro Session II
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6
Hunting for the host galaxy groups of binary black holes and the application in constraining Hubble constant
The discovery of gravitational-wave (GW) signals, produced by the coalescence of stellar-mass binary black holes (SBBHs), opens a new window to study the astrophysical origins and dynamical evolutions of compact binaries. In addition, these GW events can be treated as the standard sirens to constrain various cosmological parameters. Both issues require the host identification for these GW events, with help of the spatial resolution of GW detector networks. In this paper, we investigate the capabilities of various detector networks for identifying the SBBHs’ host galaxy groups, rather than their host galaxies, which can overcome the influence of galaxies’ proper motions in dark matter haloes for measuring the cosmological parameters. In our analysis, the group catalogue of SDSS DR7 with redshift z ∈ (0.01, 0.1) is considered as an example of the application. We find that for the second-generation (2G) detector network, the host galaxy groups of around (0.7–6.9) SBBHs can be identified per year assuming all sources are 30–30 M⊙ binaries, and that all five detectors in the network are in lock 100 per cent of the time. For the 3G detector network, this number becomes (3.9–40.0) yr−1. We also investigate the potential constraint on the Hubble constant H0 by these GW events, if their redshift information is extracted from the candidates of host galaxy groups. We find that, by 5-yr full time observations, 2G detector network is expected to give a constraint of H0/H0 ∼ (1 per cent, 4 per cent), which can be more than two order smaller if considering the 3G detector network.
Speaker: Jiming Yu -
7
Hosts and triggers of AGNs in the Local Universe
Based on the spectroscopic and shear catalogs for SDSS galaxies in the local Universe, we compare optically-selected active galactic nuclei (AGNs) with control star-forming and quiescent galaxies on galactic, inter-halo and larger scales. We find that AGNs are preferentially found in two specific stages of galaxy evolution: star-burst and `green valley' phases, and that the stellar population of their host galaxies is quite independent of stellar mass, different from normal galaxies. Combining galaxy-galaxy lensing and galaxy clustering on large scales, we measure the mass of AGN host halos. The typical halo mass is about $10^{12}h^{-1}{\rm M_\odot}$, similar to the characteristic mass in the stellar mass-halo mass relation (SHMR). For given stellar mass, AGN host galaxies and star-forming galaxies share the same SHMR, while quiescent galaxies have more massive halos. Clustering analysis on halo scales reveals that AGNs are surrounded by a larger number of satellites (with stellar mass down to 1/1000 of the mass of the central galaxy) than star-forming galaxies, and that galaxies with larger stellar velocity dispersion have more satellites. The number of satellites also increase with halo mass, reaching unity around $10^{12}h^{-1}{\rm M_\odot}$. Our results suggest a scenario, in which the interaction of the central galaxy with the satellites triggers an early episode of star burst and AGN activities, followed by multiple AGN cycles driven by the non-axisymmetric structure produced by the interaction. The feedback from the starburst and AGN reduces the amount of cold gas for fueling the central black hole, producing a characteristic halo mass scale, $\sim 10^{12}h^{-1}{\rm M_\odot}$, where the AGN fraction peaks.
Speaker: Dr Ziwen Zhang (University of Science and Technology of China) -
8
极端光变类星体样本的构建和研究
本次报告中我将介绍近期我们从SDSS DR14 quasar catalog中构建出的，目前为止最大的一批极端光变类星体(EVQs)样本，包括其搜寻方法、物理性质和相关物理过程的探讨。EVQs被认为是用来研究变脸(changing-look)类星体以及类星体点燃和熄灭过程(turn on/off)比较理想的样本，对这种传统模型难以解释的短时标大幅度光变源的研究也可以加深我们对星系核活动相关物理过程的认识。因此我们近期从SDSS DR14Q出发结合PAN-STARRS数据，通过谨慎的筛选，找到了14,012个类星体样本，并根据其光谱观测时的高低态进行了分类叠加，分析了不同状态下EVQs与对照组在连续谱和宽发射线上的区别。此外我们还将简要介绍目前针对该样本中个源的研究进展和计划。
Speaker: Wenke Ren (University of Science and Technology of China) -
9
Anisotropic neutrinos and gravitational waves from black hole neutrino-dominated accretion flows in fallback core-collapse supernovae
Fallback in core-collapse supernovae (CCSNe) plays an important role in determining the properties of the central compact remnants, which might produce a black hole (BH) hyperaccretion system in the centre of a massive CCSN. When the accretion
rate is extremely high and neutrino cooling is dominant, the hyperaccretion should be in the phase of the neutrino-dominated accretion flows (NDAFs), and thus a large number of anisotropic MeV neutrinos will be launched from the disc along with
the strong gravitational waves (GWs). In this paper, we perform a series of one-dimensional CCSN simulations with the initial explosion energy in the range of 2−8 B (1 B = 10^51 erg) to investigate the fallback processes. By considering the evolution of the central BH mass and spin in the fallback accretion, we present the effects of the initial explosion energies, masses, and metallicities of the massive progenitor stars on the spectra of anisotropic MeV neutrinos and the waveform of GWs from NDAFs. These neutrino or GW signals might be detected by operational or future detectors, and the multimessenger joint detections could constrain the properties of CCSNe and progenitor stars.Speaker: Yunfeng Wei (Xiamen University) -
10
Composite Dark Matter and XENON1T Direct Detection
Recently, the XENON1T experiments has reported the possible detection of an excess in the electronic recoil spectrum. We use mirror DM and plasma DM model to explain this excess and predict the possible signal in the future nuclear direct detection.
Speaker: Mr Lei Zu (purple mountain observatory)
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6
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Poster Session
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11
面内旋转磁场下CsV3Sb5的c轴电阻二度对称性的发现
过渡金属化合物中，因为电荷、自旋、晶格、轨道等自由度之间的相互作用，很多有序态之间具有相似的能量。其中有个常见的态是电子向列相，它的出现破坏了晶体的面内旋转对称性，并经常和其他态共存、互相影响、合作或竞争。而具有kagome晶格的材料包含丰富的奇异电子特性，比如自旋液体、电荷密度波、超导和拓扑态等。最近，新的拓扑kagome金属家族AV3Sb5 (A = K, Rb, or Cs) 被发现，并迅速引起了广泛关注。我们在CsV3Sb5单晶的面内旋转磁场并测量c方向的电阻率，观测到c方向的电阻率无论在超导态还是正常态都具有二度旋转对称性，并且超导态和正常态对应曲线的极值角度方向相互垂直。我们的研究结果为理解CsV3Sb5特殊的物理性质提供了新的思路。
Speaker: Dr Ying Xiang (Nanjing University) -
12
几种镍氧化物块材中超导电性的探索
最近，有研究者在几种镍氧化物薄膜 R1-xAxNiO2 (R = La, Pr, Nd; A = Ca, Sr) 中发现了约 5-15 K 的超导电性，这引起了超导和材料相关领域的极大关注。由于其母相 RNiO2 中Ni的 3d9 核外电子排布与铜基高温超导母体极其相似，因此人们认为这两类材料中的超导电性可能具有相同的起源。我们利用高温高压和低温软化学还原相结合的三步合成方法，成功制备了块材 Nd1−xSrxNiO2 (x = 0, 0.2, 0.4)，Sm0.8Sr0.2NiO2和Nd4Ni3O8系列多晶样品。通过结构和成分分析发现，虽然(Nd,Sm)1−xSrxNiO2中Sr的掺杂量已经接近其名义值，但是常压和高压下的低温物性测试表明块材112相为顺磁绝缘体，没有发现超导信号。在具有三层NiO2面的镍氧化物Nd4Ni3O8中，发现其低温电阻和磁化行为与Nd1−xSrxNiO2类似，依然表现出顺磁绝缘行为。高压电阻测试发现Nd4Ni3O8的绝缘性随着压力的增加先是减小后急剧增大，其高压力下绝缘性的异常增强可能与压力诱导的结构相变有关。以上关于块材镍氧化物的相关研究，对镍基块材中超导电性的进一步探索具有一定的指导意义。
Speaker: Dr Qing Li (Nanjing university) -
13
Evaluating the origins of the secondary bias based on the correlation of halo properties with the linear density field
Using two sets of large $N$-body simulations, we studied the origins of the correlations between halo assembly time ($z_{\rm f}$), concentration ($v_{\rm max}/v_{\rm 200}$), and spin ($\lambda$) with the large-scale evolved density field at given halo mass, namely, the secondary bias. We find that the secondary bias is a secondary effect resulting from the correlations of halo properties with the linear density estimated at the same comoving scale. Using the linear density on different scales, we find two types of correlations. The internal correlation, which reflects the correlation of halo properties with the mean linear over-density, $\delta_{\rm L}$, within the halo Lagrangian radius, $R_{\rm L}$, is positive for both $z_{\rm f}$ and $v_{\rm max}/v_{\rm 200}$, and negative for $\lambda$. The external correlation, which describes the correlation of halo properties with linear overdensity at $R>R_{\rm L}$ for a given $\delta_{\rm L}$, shows trends that are contrary to the internal correlation. Both of the external and internal correlations depend only weakly on halo mass, indicating a similar origin for halos of different masses. Our findings offer a transparent perspective on the origins of the secondary bias, which can be largely explained by the competition between the external and internal correlations with the correlation of the linear density field on different scales. The combination of these two types of correlations has the potential to establish the complex halo-mass dependence of the secondary bias observed in the simulations.
Speaker: Xiaoyu Wang (USTC) -
14
Single particle tunneling microscopy and vortex bound states in the layered superconductor KCa2Fe4As4F2
We perform scanning tunneling microscopy/spectroscopy (STM/STS) study on the layered iron based superconductor KCa2Fe4As4F2 with a critical temperature of about 33.5 K. The commonly obtained surface shows full-gap feature with energy gap values close to 4.6 meV. This type of spectrum presents a uniform full gap in space indicating the absence of gap nodes in this superconductor. Quasiparticle interference patterns have also been measured, which show an intra-band scattering pattern possibly due to the hole-like pocket. In addition, we observe discrete bound states with energy levels deviating from the widely believed ratio of 1:3:5 in vortices. Friedel oscillations of vortex bound states are also observed for the first time in related vortices. By doing self-consistent calculations of Bogoliubov-de Gennes equations, we find that at extreme quantum limit, i.e.,T/T_c≪Δ/E_F, the superconducting order parameter exhibits a Friedel-like oscillation, which modifies the energy levels of the vortex bound states and explains why it deviates from the ratio of 1:3:5. Our STM measurements on KCa2Fe4As4F2 reveal its nodeless superconducting gap nature and generalized feature of vortex bound states, which provide a comprehensive understanding in this highly layered iron-based superconductor.
Speaker: Mr Xiaoyu Chen (Nanjing University) -
15
Sky survey of VHE gamma ray sources with LHAASO-WCDA
Very high energy (VHE,>100 GeV) gamma-rays open a crucial window to explore the "non-thermal Universe". High-sensitivity, unbiased surveys of the gamma-ray sky are important to find new astrophysical objects - both to understand their bulk properties, and to constrain new physics beyond the standard model. Up to now, more than 230 sources are detected mainly by IACT (like Whipple, HESS, MAGIC and VERITAS) and ground-based detectors (like MILAGRO, ARGO-YBJ, HAWC). The Water Cherenkov Detector Array (WCDA) is a major component of the Large High Altitude Air Shower Array Observatory (LHAASO), expected to be about four times more sensitive than HAWC in the 1-10 TeV region. With large field of view (FOV) and high duty cycle, WCDA is expected to discovery more weak sources located at northern sky.
Speaker: Shicong Hu (Institute of High Energy Physics, Chinese Academy of Sciences) -
16
Di-boson simulation and precise measurement of Zγ analysis in ATLAS Detector
Di-boson process is one important test of the Standard Model Electroweak Symmetry Breaking, and also
backgrounds for many new physics searches. The study shows the simulation and precise measurement of di-boson
process in pp collisions at s = 13TeV, using a full dataset corresponding to an integrated luminosity of 139 fb−1
recorded with the ATLAS detector at the LHC. Di-boson process is also sensitive to anomalous triple gauge coupling which provide an opportunity to perform Beyond Standard Model study.Speaker: Danning Liu (TDLI) -
17
Gauge-Gravity Duality under Kaluza-Klein Compactification: From String to Field
The scattering amplitudes of massive Kaluza-Klein (KK) states of open and closed bosonic strings play an important role in studying the duality between the gauge and gravity theories. We analyze the structure of vertex operators for the KK strings and derive an extended massive KLT-like relation which connects the $N$-point KK closed-string amplitude to the products of two KK open-string amplitudes at tree level. Taking the zero $\alpha'$ limit, we derive double-copy construction formula of the $N$-pointmassive KK graviton amplitude from the sum of proper products of the corresponding KK gauge boson amplitudes. Then, we can obtain the exact tree-level four-point KK gauge boson amplitudes and KK graviton amplitudes via string-based formula, which fully agree with those given by the KK field-theory calculations. Further, the five- and six-point scattering amplitudes of KK states are also listed.
Speaker: Mr Yanfeng Hang -
18
Implement NN Pixel Clustering in ATLAS Inner Detector Trigger for b-jet Signature
This study has finished the implementation of NN pixel Clustering algorithm of Athena release 22 in the ATLAS Inner Detector Trigger analysis framework for the b-jet signature. An improvement in the tracking efficiency is observed in release 22 offline tracking. The study also helps to improve the tracking efficiency by modifying the truth level tracking information.
Speaker: Mr Zhen Wang (TDLI) -
19
Optomechanical atomic force microscope
In the scanning probe microscope system, the weak signal detection of cantilever vibration is one of the important factors affecting the sensor sensitivity. In our current work, we present a novel design concept for an atomic force microscope (AFM) combined with optomechanics with an ultra-high quality factor and a low thermal noise. The detection system consists of a fixed mirror placed on the cantilever of the AFM and pump-probe beams that is equivalent to a Fabry–Perot cavity. We realize that the AFM combined with an optical cavity can achieve ultra-sensitive detection of force gradients of 10^−12 N m^−1 in the case of high-vacuum and low effective temperature of 1 mK, which may open up new avenues for super-high resolution imaging and super-high precision force spectroscopy.
Speaker: Mr Fei He (SJTU) -
20
Probing environmental quenching in the Fornax cluster through a population-orbital superposition method
We probe the effect of cluster environment to the star formation quenching in galactic thin disks for 18 galaxies (17 early-type, 1 late-type) in the Fornax cluster. High quality data resolving the kinematical and chemical information across the observational plane are obtained through IFU observations with MUSE/VLT. We create population-orbit superposition models to each galaxy, the model fit the surface brightness, kinematics, age and metallicity maps simultaneously. Based on the model, we can dynamically separate the thin disk from other component of the galaxy and obtain its age distributions across the disk plane. We find 9 of the 18 galaxies show positive age gradient on the cold disk. With the help of our model and infall time classification based on the cluster phase-space, we find recent infallers are mostly with higher cold disk fraction, younger cold disk and positive age gradient while ancient infallers have older and smaller disks which show negative age gradient. By comparing with simulation, we find that positive age gradient is strong evidence of environmental quenching.
Speaker: Yuchen Ding (Shanghai astronomical observatory) -
21
Semi-leptonic 𝑡𝑡 ̅ Calibration for 𝑋→𝑏𝑏 ̅ tagger
The identification of massive particles decaying into bottom quark pairs is important for the physics program of the ATLAS experiment at the Large Hadron Collider. A neural network (NN) based double b-tagging algorithm named 𝑋→𝑏𝑏 ̅ tagger is developed and calibrations of the tagger are performed using proton-proton collision data corresponding to 139/𝑓𝑏 collected at a centre-of-mass energy of √𝑠=13𝑇𝑒𝑉.
The technique of 𝑋→𝑏𝑏 ̅ mis-tag rate calibration [1] is developed based on semi-leptonic decay 𝑡𝑡 ̅ events which provide typical non-𝑏𝑏 ̅ flavor combination and high statistics. The mis-tag efficiency is measured and the scale factor, which is defined as the ratio of the mis-tag rate measured in the data over the one in simulation, is found to be in a range of 1~1.1 with uncertainty less than 16%.Speaker: Qibin LIU -
22
Split Invariant Curves In Rotating Bar Potentials
Invariant curves are generally closed curves in the Poincare ́ surface of section. Here we study an interesting dynamical phenomenon, first discovered by Binney (1985) in a rotating Kepler potential, where an invariant curve of the surface of section can split into two disconnected line segments under certain conditions, which is distinctively different from the islands of resonant orbits. We first demonstrate the existence of split invariant curves in the Freeman bar model, where all orbits can be described analytically. We find that the split phenomenon occurs when orbits are nearly tangent to the minor/major axis of the bar potential. Moreover, the split phenomenon seems ‘‘necessary’’ to avoid invariant curves intersecting with each other. Such a phenomenon appears only in rotating potentials, and we demonstrate its universal existence in other general rotating bar potentials. It also implies that actions are no longer proportional to the area bounded by an invariant curve if the split occurs, but they can still be computed by other means.
Speaker: Ms Tianye Xia (1Department of Astronomy, School of Physics and Astronomy, Shanghai Jiao Tong University )
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11
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Astro Session III
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23
Searching dark matter around Super-Massive Black Hole
Dense dark matter is predicted around super-massive black hole (SMBH). Recently, the Event Horizon Telescope and GRAVITY groups, which focus on M87* and Galactic Center, have published their observations, which provide us a good chance to search dark matter.
Speaker: Mr Guan-Wen Yuan (Purple Mountain Observatory) -
24
Constraining scalar-tensor theories by neutron star-black hole gravitational wave events
With the continuous upgrade of detectors, more and more gravitational wave (GW) events were captured by the LIGO Scientific Collaboration and Virgo Collaboration (LVC), which offers a new avenue to test General Relativity and explore the nature of gravity. Although, various model-independent tests have been performed by LVC in previous works, it is still interesting to ask what constraints on specific models can be placed by current GW observations.
In this work, we focus on three models of scalar-tensor theories, the Brans-Dicke theory (BD), the theory with scalarization phenomena proposed by Damour and Esposito-Far`{e}se (DEF), and Screened Modified Gravity (SMG). From all 4 possible NSBH events so far, we use two of them to place the constraints. The other two are excluded in this work due to the possible unphysical deviations.
We consider the inspiral range with the cutoff frequency at the innermost stable circular orbit and add a modification of dipole radiation into the waveform template. The scalar charges of neutron stars in the dipole term are derived by solving the Tolman-Oppenheimer-Volkoff equations for different equations-of-states. The constraints are obtained by performing the full Bayesian inference with the help of the open source software \texttt{Bilby}.
The results show that the constraints given by GWs are comparable with those given by pulsar timing experiments for DEF theory, but are not competitive with the current solar system constraints for BD and SMG theories.
Speaker: Mr Rui Niu (School of Astronomy and Space Sciences, University of Science and Technology of China, Hefei 230026, China) -
25
Postglitch Analysis of Crab Pulsar For Proposing Internal Torque Mechanism
Link(1992) considered the newly-developed observation could be a strong evidence for external torque interpretation of persistent offset, developed by Ruderman(1991), We conclude in this talk that after 30 years of accumulation of observation data volume, new observational evidence has in turn been able to rule out the external torque explanation in favor of the internal mechanism associated with cooper pair breaking, which also will be proposed in theoretical approach, This is mainly due to the fact that larger glitch data are beyond the maximum possible range of external torque mechanism could produced and the nonlinear trend of post glitch behavior cannot be resolved in the framework of the exsisting external mechanism models.
Speaker: Chun Huang (Central China Normal University) -
26
Research progress of Microwave Kinetic Inductance Detectors in PMO
Microwave Kinetic Inductance Detectors(MKIDs) are very promising superconducting detector arrays used in the field of terahertz astronomy. It has attracted much attention due to its simple implementation of frequency-multiplexing readout technology. The Purple Mountain Observatory(PMO) of the Chinese Academy of Sciences has carried out related research on the MKIDs detector based on the Antarctic DATE5 telescope as the background. Therefore, in this report, we will introduce our recent research on the MKIDs detector at the PMO.
Speaker: Dr weitao Lv (doctoral students)
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23
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Dinner
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Poster Discussion
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Quamtum Session I
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27
Topological holographic quench dynamics in synthetic frequency space
Characterization the equilibrium topological invariants through the dynamics quench process attracts extensive interests very recently. Usually, the characterization of non-equilibrium topological invariants shown during the dynamics quench requires information in both the time and spatial dimensions. We propose the topological holographic quench dynamics in synthetic dimension to characterize photonic topological phases. We use ring resonators to construct a pseudo spin model in the synthetic frequency dimension. The quench dynamics is triggered by initializing a trivial state which evolves under a topological Hamiltonian. Our key result is that the complete topological invariance of the Hamiltonian contained in quench dynamics can be directly demonstrated solely using the information along the time dimension. In particular, two time scale are shown during the dynamical evolution, with one time scale mimicking the Bloch momentum dimension and the other mimicking the time evolution of the state. Hence, the quench dynamic is reconstructed in the two time scales, and the non-equilibrium topological invariants is obtained by using the information on the band inversion surfaces (BIS). Therefore, a universal correspondence between the quench dynamics and the equilibrium topological invariance of the spin model is obtained through utilizing the evolution of the field in the modulated ring resonators solely along the time dimension in simulations. This work shows that photonics synthetic frequency dimension can be used to study the topological non-equilibrium dynamics through quench dynamics [Light. Sci. Appl. 10, 209 (2021)].
Speaker: Danying Yu (Shanghai Jiao Tong University) -
28
耦合腔波导中基于巨原子的光子局域态激发
在原子—波导系统中研究光与原子相互作用，有益于在量子信息处理中实现光子传输的灵活操控。近年来，利用量子超导电路平台，人们制备了与波导多点发生耦合的人工巨原子，为波导光子与原子相互作用搭建了多路径的量子干涉通道。耦合腔波导不同于连续波导，人们将动态调制源应用到腔与腔的连接处，可以进一步操控光子的空间分布和频谱分布。我们从理论上探究了，光子在动态调制的耦合腔波导中与二能级巨原子相互作用后的传输特性。研究发现，在特定的参数选择下光子被局域在耦合点附近的谐振腔中，同时被激发的原子表现出亚辐射衰变的特性[arXiv:2111.06764]。为了解释这一光子束缚态的现象，我们提出了基于动量空间的模式分离近似方法，解析表明，初始处于传输态的入射光子被转换到局域态是由波导光子与巨原子相互作用中多路径的量子干涉效应做导致的。此外，我们研究的实空间模型也可以拓展到合成频率维度，利用电光调制器动态调制谐振环内传输光子的频率模式，模拟一维合成频率维度中原子与不同频率模式光子相互作用。我们的工作深入研究了基于巨原子与耦合腔波导耦合所引起的多路径量子干涉效应对光子传输的影响，为原子—波导系统中激发光子局域态提供了理论方法，为量子通讯和量子计算等技术的实现提供了应用前景。
Speaker: Mr 瀚 肖 (上海交通大学) -
29
铁掺杂Bi2Sr2CaCu2O8+δ中直接观测到非公度的反铁磁序
在铜氧化物超导体中，由于电子的强关联特性，有许多与超导态共存或者与超导竞争的序。它们中反铁磁序是其中最主要的一个。往往在相图中超导出现的区域长程反铁磁已经被破坏了，但在高掺杂下会出现剩下的短程反铁磁涨落。它们在超导态中所扮演的角色仍然被高度的关注。这里我们利用自旋极化的扫描隧道显微镜，第一次直接观测到在掺杂进最佳掺杂的Bi2Sr2CaCu2O8+δ的Fe原子附近的一个非公度反铁磁序。Fe杂质压制了超导能隙结构中相干峰的强度，破坏了超导相干，但也将短程的非公度反铁磁序钉扎下来。我们的工作揭示了超导与反铁磁的密切关系，为理解高温超导与反铁磁的相互作用与高温超导配对提供了新的认识。
Speaker: Mr Siyuan Wan (National Laboratory of Solid State Microstructures and Department of Physics, Center for Superconducting Physics and Materials, Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing China) -
30
Kagome金属CsV3Sb5中电荷密度波的机制
近期新发现的Kagome金属家族AV3Sb5 (A = K, Rb, or Cs)展现出电荷密度波、超导电性以及拓扑非平庸的Dirac能带, 迅速引起凝聚态物理学界的广泛关注，其中电荷密度波的驱动机制及其与超导电性的关系是当前该领域争论的焦点。我们利用红外光谱对CsV3Sb5中的电荷密度波进行了研究。结果显示，在TCDW=91 K以上，低频的光电导由两个Drude分量组成（窄Drude分量D1、宽Drude分量D2）。通过对CsV3Sb5电子能带结构的计算，我们发现由于D1具有较小的散射率，其源于Γ点附近的轻电子带及K点附近的Dirac带的带内跃迁；而D2散射率较大，因此对应M点附近的重空穴带的带内跃迁。当温度降至TCDW以下时，D1谱重几乎没有发生变化，而D2谱重被大幅压制且转移到了高频。与此同时，鞍点附近的带间跃迁引起的吸收峰的共振频率向高频移动并且谱重增加。这些实验结果表明，M点处的鞍点之间的嵌套可能是CsV3Sb5中电荷密度波的驱动机制。
Speaker: Dr Xiaoxiang Zhou (Nanjing University)
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27
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Coffee Break
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Quantum Session II
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31
A new proposal to discern the transverse-field Ising chain universality
There has been considerable recent progress in identifying candidate materials for the transverse-field Ising chain (TFIC), a paradigmatic model for quantum criticality. Here, we study the local spin dynamical structure factor of different spin components in the quantum disordered region of the TFIC. We show that the low-frequency local dynamics of the spins in the Ising- and transverse-field directions have strikingly distinctive temperature dependencies. This leads to the thermal-activation gap for the secular term of the NMR $1/T_2$ relaxation rate to be half of that for the $1/T_1$ relaxation rate. Our findings reveal a new surprise in the nonzero-temperature dynamics of the venerable TFIC model and uncover a means to evince the material realization of the TFIC universality.
Speaker: Mr Jiahao Yang (Tsung-Dao Lee Institute) -
32
$E_{8}$ excitation in quantum critical Ising chain and its experimental observations
The transverse field Ising chain (TFIC) at its quantum critical point (QCP) in the scaling limit turns to be a central charge 1/2 conformal field theory (CFT). In the vicinity of a small longitudinal magnetic field, eight quasiparticles emerge and the whole system can be described by exceptional $E_{8}$ Lie algebra. This excitation essentially arises from weak confinement due to the perturbation, such that can be treated as meson excitations from two quarks, originally from the idea of McCoy and T. T. Wu. In such a case, this perturbed CFT becomes an integrable field theory (IFT). By calculating the form factor of this IFT, spectrum of multi-$E_{8}$ particle channel can be obtained analytically. Experimentally, the TFIC universality class with longitudinal field perturbation is necessary to realize this $E_{8}$ excitation, which can be achieved in the material BaCo$_2$V$_2$O$_8$ near its QCP. In this talk, I will introduce form factor theory and the spectra analytical properties of this IFT, then show this spectrum in spin dynamical experiments in the material BaCo$_2$V$_2$O$_8$. The results show great power of universality class, bridge the key physics of condensed matter physics, statistical field theory and conformal field theory.
Speaker: Xiao Wang (Tsung-Dao Lee Institute) -
33
超快激光操控量子材料的电子维度
强激光与多体系统相互作用可以诱导非平衡态的新奇物理现象，例如光致超导、光致亚稳态、光激发相干声子模式和光致拓扑缺陷的产生等。激光脉冲泵浦激发固体材料中的电子提供了一种通过非热方式诱导新颖量子态产生的手段，可以在飞秒至皮秒级的时间尺度上操控材料的宏观属性。最近我们的研究发现，利用飞秒激光可以部分翻转三维电荷密度波材料中的周期性晶格扰动，实现瞬时的二维长程有序电子态，这些研究使得激光对量子材料的操控成为当前的研究热点。相应的电子和晶格动力学可以分别由时间分辨角分辨光电子能谱（trARPES）和超快电子衍射（UED）探测。更有趣的是，光诱导的二维电子态的表面有能隙的打开，这可能是光致非平衡态超导的迹象。利用超快激光调制原子的移动是一种实现二维电子态的新方法，并将成为在量子材料中创造新物质相的新方法。
Speaker: Dr 绍峰 段 -
34
FeSe超导体的时间分辨角分辨光电子能谱研究
铁基超导体是第二大类高温超导材料，其具备丰富的相图，通过改变压力或者施加磁场的方式可以实现不同量子相之间的转变。向列相相变是铁基超导体中备受关注的话题，即在发生温度变化时，伴随着高温四方相向低温正交相的晶格结构的相变，电子结构会发生面内的对称性破缺。利用时间分辨角分辨光电子能谱（trARPES）技术，可以直接的对铁基超导体中电子向列相的起源以及与超导相之间的关联进行探索，进一步理解铁基超导体中高温超导的配对机制。FeSe是晶格结构最简单的铁基超导体，其超导转变温度Tc~8 K，向列相转变温度Ts~90 K,且并没有伴随着磁结构的相变，为探究纯的电子向列相与超导相之间的关联提供了独一无二平台。本研究利用trARPES对FeSe中具备不同轨道特征的能带，在激光泵浦之下的超快演变过程进行了探测。我们发现在超快激光泵浦作用下， FeSe超导体的非平衡电子态中存在两个转变，可能意味着两个纯的电子结构相变。本研究对探究铁基超导体中电子向列相的起源及与超导相之间的关联提供了新的理解。
Speaker: Yuanyuan Yang -
35
The vierbein geometric theory for twisted bilayer graphene and rotating bilayer graphene
TBG and moire system have attracted huge interest in both experimantal and theoretical community due to its exotic strong correlated properties and rich phase diagram. However there is still lack of a general theory for arbitrary twisted angle without commensurate approximation. And the superconductive pairing mechanism in TBG is still controversial.
We propose a new kind of geometric theory for TBG. By using vierbein formalism one can
consider the coupling between Dirac fermion and effective curved space-time in single valley. The spin connection will act as a compact SU(2) gauge field to induce Landau level. This formalism is in principle valid for any twisted angle without dislocation. Numerical calculation indicates there are flat bands at the first magic angle θm1=1.05°with band width about 5meV, which is coincide with former results. When this effective curved space is embedded intothe background Euclidean space, the band will be non-hermitian in general. Moreover, such theory can be generalized to the situation for rotating bilayer graphene (RBG). RBG is hardly described by former theories. By investigating the Bott index for finite size RBG, we can relate the Bott index with corresponding charge pumping per driven period (as 2d Thouless pump). This theory may be verified by certain transportation experiment.Speaker: Jia-Zheng Ma (Sun-Yat sen University)
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31
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Lunch&&Break
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Nuclear&Particle Session I
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36
Flavor-changing Majoron interactions with leptons
When the Standard Model Higgs sector is extended with a complex singlet that breaks global lepton number symmetry spontaneously, a massless Goldstone boson called the Majoron $J$ arises. In addition to increasing Higgs invisible decay through mixing, the Majoron can generally have flavor-changing interactions with fermions.
We find that type-III seesaw model poses such interesting properties with both charged leptons and neutrinos.
This opens up new channels to search for the Majoron. We use the experimental data such as muonium-anti-muonium oscillation and flavor-changing neutrino and charged lepton decays to put constraints on the couplings. As a novel way to reveal the chiral properties of these interactions, we propose an experimentally measurable polarization asymmetry of flavor-changing $\ell \to \ell' J$ decays.Speaker: Mr Jin Sun (TDLI, SJTU) -
37
Dissecting Axion and Dark Photon with A Network of Vector Sensors
We explore the applications of a network of vector sensors, sensitive to certain spatial components of the signals, in identifying the property of light axion or dark photon background. These bosonic fields contribute to vector-like signals in the detectors, including effective magnetic fields triggering the spin precession, effective electric currents in a shielded room, and forces on the matter. The interplay between a pair of vector sensors and a baseline that separates them can potentially uncover rich information of the bosons, including angular distribution, polarization modes, source localization, and macroscopic circular polarization. Using such a network, one can identify the microscopic nature of a potential signal, such as distinguishing between the axion-fermion coupling and the dipole couplings between the dark photon and fermions.
Speaker: Yanjie Zeng (Institute of Theoretical Physics, Chinese Academy of Sciences) -
38
Overview of PandaX-4T recent results
The PandaX-4T experiment will utilize a two-phase liquid/gas xenon time projection chamber to search dark matter. The PandaX-4T is located in the Hall B2 of the Jinping Underground Laboratory with 2400 m overburden. In the commissioning run, 1058 candidate events are identified with 3.7-tonne of liquid xenon target and an exposure of 0.63 tonne·year. A stringent limit to the dark matter-nucleon spin-independent interactions is set with a lowest excluded cross section (90% C.L.) of $3.8 \times 10^{-47}$ cm$^2$ at a dark matter mass of 30 GeV/c2. An details of the detector performance and data analysis will be presented in this talk.
Speaker: Mr Zhou Huang (Shanghai Jiao Tong University) -
39
费米实验室缪子反常磁矩实验
费米实验室的缪子g-2实验对缪子的反常磁矩进行了精确的测量，首批物理结果现已公布。最新的实验结果表明缪子反常磁矩的理论预言与实验测量之间存在4.2σ的偏差，为新物理的存在提供了强有力的证据，预示着世界上可能存在新的未知粒子或者作用力。
缪子反常磁矩由两个角频率的精确测量确定。实验中，缪子受强磁场束缚在储存环内运动，通过统计缪子衰变产生的高能电子数目得到缪子的反常进动频率ω_a。利用脉冲核磁共振技术，测量质子的自旋进动频率ω_p表征强磁场的大小。结合上述两个频率以及缪子在储存环中的分布函数和其他已知常数可以精确的测量缪子的反常磁矩。首批物理结果的测量精度达到了0.46ppm，后继测量结果的精度将进一步提高，预计于2022年发布。
Speaker: bingzhi li
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36
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Coffee Break
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Nuclear&Particle Session II
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40
Spacer configuration optimization for RPCs based on COMSOL Multiphysics simulation
The uniformity of the gas flow in the chamber and the deformation of the electrode plates are critical to the performance of RPC (Resistance Plate Chamber). In this talk, a new design of RPC with “shifted” spacer configuration and less spacer number is come up. The different behaviors of the flow field, electrode’s deformation and electric field between RPCs with new spacer configuration and classical aligned configuration are studied through COMSOL Multiphysics which is a simulation platform based on finite element method.
Speaker: Lining Mao -
41
Fast Timing Readout Electronic based on PETIROC ASIC
Semi-Digital Hadron Calorimeter (SDHCAL) prototype for CEPC is a PFA-based hadron calorimeter that has shown good energy and position resolution with a CERN test beam. Considering the signal time of hadronic shower formed by neutrons is delayed, compared with that from charged hadrons, high-precision time measurement, requiring at least 100ps orders, helps improve separation between
neutrons and charged hadrons and further improve the jet energy resolution. The readout electronics with four PETIROC ASIC chips have been designed to validate the high time resolution with tens of ps.Keywords: CEPC, SDHCAL, PETIROC, ASIC, High Time Resolution.
Speaker: Mr Qiuping SHEN (Shanghai Jiao Tong University) -
42
丰质子原子核质量的预言
原子核的质量是核物理中最基本的物理量之一，原子核质量的预言在核物理以及核天体领域中具有广泛且重要的应用。镜像核质量公式基于同位旋对称性和库仑相互作用，对丰质子区原子核质量进行精确描述，公式的精度达到 110–130 keV。通过奇偶性分组拟合和残差关联效应，质量公式的精度进一步降低到 50–90 keV。通过使用镜像核质量公式，可以对丰质子区原子核的质量进行预言，预言值和最新实验数据精确吻合。
Speaker: Mr Zong Yaoyao -
43
Collins-Soper kernel from transverse momentum-dependent wave functions in LaMET
In this work we present the analysis of Collins-Soper kernel extracted from pion transverse momentum dependent wave functions in the framework of large momentum effective theory from lattice QCD. We use clover fermion action with $2 + 1 + 1$ flavors of highly improved staggered quarks (HISQ), with lattice spacing $a=0.12$fm and volume $L^3\times T=48^3\times64$. The results are obtained based on pion mass $M_{\pi}=670$MeV, and three hadron momenta as $P^z = 2\pi/L\times\{8, 10, 12\} = \{1.72, 2.15, 2.58\}$GeV. Preliminary results are found in consistent with previous LQCD determinations and phenomenological results.
Speaker: Mr Min-Huan Chu (Shanghai Jiao Tong University)
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40
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Coffee Break
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Closing Ceremony
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Dinner
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