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Gravitational Equivalence Theorem and Double-Copy for Kaluza-Klein Graviton Scattering Amplitudes

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Research 2022年第4期2022卷 411-420页

作者： Yan-Feng Hang Hong-Jian He tsung-dao lee institute and School of physics and Astronomy Key Laboratory for Particle Astrophysics and Cosmology(MOE)Shanghai Key Laboratory for Particle Physics and CosmologyShanghai Jiao Tong UniversityShanghaiChina institute of Modern physics and Department of physics Tsinghua UniversityBeijingChina Center for High Energy physics Peking UniversityBeijingChina

We analyze the structure of scattering amplitudes of the Kaluza-Klein (KK) gravitons and of the KK gravitational Goldstone bosons in the compactified 5d general relativity (GR). Using a general Rξ gauge fixing, we study the geometric Higgs mechanism for the massive spin-2 KK gravitons. We newly propose and prove a gravitational equivalence theorem (GRET) to connect the scattering amplitudes of longitudinal KK gravitons to that of the KK gravitational Goldstone bosons, which formulates the geometric gravitational Higgs mechanism at the scatteringS-matrix level. We demonstrate that the GRET provides a general energy cancellation mechanism guaranteeing the N-point longitudinal KK graviton scattering amplitudes to have their leading energy dependence cancelled down by a large power factor of E^(2N)(N≥4) up to any loop level. We propose an improved double-copy approach to construct the massive KK graviton (Goldstone) amplitudes from the KK gauge boson (Goldstone) amplitudes. With these, we establish a new correspondence between the two types of energy cancellations in the four-point longitudinal KK amplitudes at tree level: E^(4)→E0 in the KK gauge theory and E^(10)→E^(2) in the KK GR theory.

关键词： theory gauge guarantee

Signal-background discrimination with convolutional neural networks in the PandaX-Ⅲ experiment using MC simulation

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Science China(physics,Mechanics & Astronomy) 2018年第10期61卷 51-59页

作者： Hao Qiao ChunYu Lu Xun Chen Ke Han XiangDong Ji SiGuang Wang School of physics and State key laboratory of Nuclear physics and Technology and Center for High Energy physics Peking University Beijing 100871 China institute of particle and Nuclear physics and School of physics and Astronomy Shanghai Jiao Tong University Shanghai Laboratory for Particle Physics and Cosmology Shanghai 200240 China tsung-dao lee institute Shanghai 200240 China

The PandaX-Ⅲ experiment will search for neutrinoless double beta decay of 136Xe with high pressure gaseous time projection chambers at the China Jin-Ping underground laboratory. The tracking feature of gaseous detectors helps suppress the background level, resulting in the improvement of the detection sensitivity. We study a method based on the convolutional neural networks to discriminate double beta decay signals against the background from high energy gammas generated by 214Bi and 2^208 T1 decays based on detailed Monte Carlo simulation. Using the 2-dimensional projections of recorded tracks on two planes, the method successfully suppresses the background level by a factor larger than 100 with a high signal efficiency. An improvement of 62% on the efficiency ratio of Еs/√Еb is achieved in comparison with the baseline in the PandaX-Ⅲ conceptual design report.

关键词： neutrino double beta decay convolutional neural networks background suppression

Topological Equivalence Theorem and Double-Copy for Chern-Simons Scattering Amplitudes

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Research 2023年第2期2023卷 43-51页

作者： Yan-Feng Hang Hong-Jjan He Cong Shen tsung-dao lee institute and School of physics and Astronomy Key Laboratory for Particle Astrophysics and Cosmology(MOE)Shanghai Key Laboratory for Particle Physics and CosmologyShanghai Jiao Tong UniversityShanghaiChina Department of physics and institute of Modern physics Tsinghua UniversityBejingChina Center for High Energy physics Peking UniversityBeijingChina Fields and Strings laboratory Institute of PhysicsEcole Polytechnique Federale de LausanneLausanneSwitzerland

We study the mechanism of topological mass generation for 3-dimensional Chern-Simons gauge theories and propose a brand-new topological equivalence theorem to connect scattering amplitudes of the physical gauge boson ... 详细信息

关键词： expansion gauge topological

The intrinsic SFRF and sSFRF of galaxies:comparing SDSS observation with IllustrisTNG simulation

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Research in Astronomy and Astrophysics 2020年第12期20卷 229-242页

作者： Ping Zhao Haojie Xu Antonios Katsianis Xiao-Hu Yang Department of Astronomy School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China tsung-dao lee institute and Shanghai Key Laboratory for Particle Physics and CosmologyShanghai Jiao Tong UniversityShanghai 200240China

The star formation rate function(SFRF) and specific star formation rate function(s SFRF) from observations are impacted by the Eddington bias, due to uncertainties in the estimated star formation rate(SFR). We develop a novel method to correct the Eddington bias and obtain the intrinsic SFRF and sSFRF from the Sloan Digital Sky Survey(SDSS) Data Release 7. The intrinsic SFRF is in good agreement with measurements from previous data in the literature that relied on UV SFRs but its high star-forming end is slightly lower than the corresponding IR and radio tracers. We demonstrate that the intrinsic sSFRF from SDSS has a bimodal form with one peak found at sSFR ~10-9.7 yr^-1 representing the star-forming objects while the other peak is found at sSFR ~10-12 yr^-1 representing the quenched population. Furthermore, we compare our observations with the predictions from the Illustris TNG and Illustris simulations and affirm that the "TNG" model performs much better than its predecessor. However,we show that the simulated SFRF and CSFRD of TNG simulations are highly dependent on resolution,reflecting the limitations of the model and today’s state-of-the-art simulations. We demonstrate that the bimodal, two peaked s SFRF implied by the SDSS observations does not appear in TNG regardless of the adopted box-size or resolution. This tension reflects the need for inclusion of an additional efficient quenching mechanism in the TNG model.

关键词： statistical galaxies:formation galaxies:distances and redshifts hydrodynamics

Size distribution of galaxies in SDSS DR7:weak dependence on halo environment

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Research in Astronomy and Astrophysics 2019年第1期19卷 61-74页

作者： You-Cai Zhang Xiao-Hu Yang key laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Department of Astronomy Shanghai Key Laboratory for Particle Physics and CosmologyShanghai Jiao Tong University IFSA Collaborative Innovation Center and Tsung-Dao Lee InstituteShanghai Jiao Tong University

Using a sample of galaxies selected from the Sloan Digital Sky Survey Data Release 7(SDSS DR7) and a catalog of bulge-disk decompositions, we study how the size distribution of galaxies depends on the intrinsic properties of galaxies, such as concentration, morphology, specific star formation rate(sSFR),and bulge fraction, and on the large-scale environments in the context of central/satellite decomposition,halo environment, the cosmic web: cluster, filament, sheet and void, as well as galaxy number density. We find that there is a strong dependence of the luminosity-or mass-size relation on the galaxy concentration, morphology, s SFR and bulge fraction. Compared with late-type(spiral) galaxies, there is a clear trend of smaller sizes and steeper slope for early-type(elliptical) galaxies. Similarly, galaxies with a high bulge fraction have smaller sizes and steeper slopes than those with a low bulge fraction. Fitting formulae of the average luminosity-and mass-size relations are provided for galaxies with these different intrinsic properties. Examining galaxies in terms of their large scale environments, we find that the masssize relation has some weak dependence on the halo mass and central/satellite segregation for galaxies within mass range 9.0 ≤ log M*≤ 10.5, where satellites or galaxies in more massive halos have slightly smaller sizes than their counterparts, while the cosmic web and local number density dependence of the mass-size relation is almost negligible.

关键词： large-scale structure of universe methods:statistical cosmology:observations

Performance of AC-LGAD strip sensors designed for the DarkSHINE experiment

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Nuclear Science and Techniques 2024年第11期35卷 152-163页

作者： Kang Liu Meng-Zhao Li Jun-Hua Zhang Wei-Yi Sun Yun-Yun Fan Zhi-Jun Liang Yu-Feng Wang Mei Zhao Kun Liu tsung‑dao lee institute Shanghai Jiao Tong UniversityShanghai 201210China key laboratory for particle Astrophysics and Cosmology(MOE) Shanghai Key Laboratory for Particle Physics and Cosmology(SKLPPC)Shanghai 200240China institute of High Energy physics Chinese Academy of SciencesBeijing 100049China State key laboratory of particle Detection and Electronics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Beijing 100049China institute of Nuclear and particle physics School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China

The DarkSHINE experiment proposes a novel approach to single-electron-on-fixed-target exploration that focuses on the search for dark photons through their invisible decay into dark matter *** to this initiative is an advanced tracking detector designed to achieve exceptional sensitivity in the detection of light dark matter *** study evaluates the performance of several prototype AC-coupled low-gain avalanche diode(AC-LGAD)strip sensors specifically developed for the DarkSHINE tracking *** electrical properties of the sensors from two batches of wafers with different n^(+)doses are thoroughly *** and temporal resolutions are measured using an infrared laser *** spatial resolutions range from 6.5 to 8.2μm and from 8.8 to 12.3μm for the sensors from two distinct dose batches,each with a 100μm pitch ***,the sensors demonstrate time resolutions of 8.3 and 11.4 ps,underscoring the potential of AC-LGAD technology in enhancing the performance of the DarkSHINE tracking detector.

关键词： The DarkSHINE experiment Silicon-strip detector AC-LGAD sensor Spatial resolution Timing resolution

Design of hadronic calorimeter for DarkSHINE experiment

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Nuclear Science and Techniques 2024年第9期35卷 155-167页

作者： Zhen Wang Rui Yuan Han-Qing Liu Jing Chen Xiang Chen Kim Siang Khaw Liang Li Shu Li Kun Liu Qi-Bin Liu Si-Yuan Song Tong Sun Xiao-Long Wang Yu-Feng Wang Hai-Jun Yang Jun-Hua Zhang Yu-Lei Zhang Zhi-Yu Zhao Chun-Xiang Zhu Xu-Liang Zhu Yi-Fan Zhu tsung-dao lee institute Shanghai Jiao Tong University1 Lisuo RoadShanghai 201210China institute of Nuclear and particle physics School of Physics and Astronomy800 Dongchuan RoadShanghai 200240China key laboratory for particle Astrophysics and Cosmology(MOE) Shanghai Key Laboratory for Particle Physics and Cosmology(SKLPPC)Shanghai Jiao Tong University800 Dongchuan RoadShanghai 200240China key laboratory of Nuclear physics and Ion-beam Application(MOE) Fudan UniversityShanghai 200443China institute of Modern physics Fudan UniversityShanghai 200443China

The sensitivity of the dark photon search through invisible decay final states in low-background experiments relies sig-nificantly on the neutron and muon veto efficiencies,which depend on the amount of material used and the design of the detector *** paper presents the optimized design of the hadronic calorimeter(HCAL)used in the DarkSHINE experiment,which is studied using a GEANT4-based simulation *** geometry is optimized by comparing a traditional design with uniform absorbers to one that uses different thicknesses at different locations on the detector,which enhances the efficiency of vetoing low-energy neutrons at the sub-GeV *** overall size and total amount of material used in the HCAL are optimized to be lower,owing to the load and budget requirements,whereas the overall performance is studied to satisfy the physical objectives.

关键词： Hadronic calorimeter GEANT4 simulation Neutron background Scintillation detector Dark photon

Weak lensing magnification reconstruction with the modified internal linear combination method

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Research in Astronomy and Astrophysics 2021年第10期21卷 51-60页

作者： Shu-Tong Hou Yu Yu Peng-Jie Zhang Department of Astronomy School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Shanghai key laboratory for particle physics and Cosmology Shanghai Jiao Tong UniversityShanghai 200240China tsung-dao lee institute Shanghai 200240China

Measuring weak lensing cosmic magnification signal is very challenging due to the overwhelming intrinsic clustering in the observed galaxy *** this paper,we modify the Internal Linear Combination(ILC)method to reconstruct the lensing signal with an extra constraint to suppress the intrinsic *** quantify the performance,we construct a realistic galaxy catalogue for the LSST-like photometric survey,covering 20000 deg^(2) with mean source redshift at z_(s)~*** find that the reconstruction performance depends on the width of the photo-z bin we *** to the correlation between the lensing signal and the source galaxy distribution,the derived signal has smaller systematic bias but larger statistical uncertainty for a narrower photo-z *** conclude that the lensing signal reconstruction with the Modified ILC method is unbiased with a statistical uncertainty <5% for bin width Δz^(P)=0.2.

关键词： cosmology:observations large-scale structure of universe weak lensing

Molecular beam epitaxy of superconducting PdTe_2 films on topological insulator Bi_2Te_3

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Science China(physics,Mechanics & Astronomy) 2019年第7期62卷 108-112页

作者： HuanYi Xue Hao Yang YanFu Wu Gang Yao Dandan Guan ShiYong Wang Hao Zheng CanHua Liu YaoYi Li JinFeng Jia key laboratory of Artificial Structures and Quantum Control (Ministry of Education) School of Physics and Astronomy Shanghai Jiao Tong University Collaborative Innovation Center of Advanced Microstructures tsung-dao lee institute

Majorana fermions have been observed in topological insulator/s-wave superconductor heterostructures. To manipulate Majorana fermions, superconducting materials should be deposited on the surfaces of topological insulators. In this study, highquality superconducting PdTe_2 films are deposited on the topological insulator Bi_2Te_3 surface using molecular beam epitaxy. The surface topography and electronic properties of PdTe_2/Bi_2Te_3 heterostructures are investigated via in situ scanning tunneling microscopy/spectroscopy. Under Te-rich conditions, the Pd atoms presumably form PdTe_2 film on Bi_2Te_3 surface rather than diffuse into Bi_2Te_3. The superconductivity of the PdTe_2/Bi_2Te_3 heterostructure is detected at a transition temperature of ～1.4 K using the two-coil mutual inductance technique. This study proposes a method for fabricating superconducting materials on topological insulator surfaces at low doping levels, paving ways for designing nanodevices that can manipulate Majorana fermions.

关键词： topological insulator superconductor heterostructure molecular beam epitaxy