This study addresses a challenge of parametrizing a resolution function of a neutron beam from the neutron time of flight facility n_TOF at CERN.A difficulty stems from a fact that a resolution function exhibits rathe...This study addresses a challenge of parametrizing a resolution function of a neutron beam from the neutron time of flight facility n_TOF at CERN.A difficulty stems from a fact that a resolution function exhibits rather strong variations in shape,over approximately ten orders of magnitude in neutron energy.To avoid a need for a manual identification of the appropri-ate analytical forms-hindering past attempts at its parametrization-we take advantage of the versatile machine learning techniques.Specifically,we parametrized it by training a multilayer feedforward neural network,relying on a key idea that such network acts as a universal approximator.The proof-of-concept is presented for a resolution function for the first experimental area of the n_TOF facility from the third phase of its operation.We propose an optimal network structure for a resolution function in question,which is also expected to be optimal or near-optimal for other experimental areas and for different phases of n_TOF operation.To reconstruct several resolution function forms in common use from a single para-metrized form,we provide a practical tool in the form of a specialized C++class encapsulating the computationally efficient procedures suited to the task.展开更多
The phenomenon of pseudogap and Fermi arcs has been a long-standing puzzle in the field of unconventional superconductivity(SC).Since first discovered in underdoped cuprates[1],the pseudogap has been generally identif...The phenomenon of pseudogap and Fermi arcs has been a long-standing puzzle in the field of unconventional superconductivity(SC).Since first discovered in underdoped cuprates[1],the pseudogap has been generally identified in various(quasi)two-dimensional(2D)contexts,including thin-film FeSe[2],layered heavy fermion systems[3],magic angle twisted bilayer graphene[4],and recently even ultra-cold atoms[5].One prominent explanation for the pseudogap is hence to treat it as a precursor of pairing due to phase decoherence.展开更多
Orthogonal metal is a new quantum metallic state that conducts electricity but acquires no Fermi surface(FS)or quasiparticles, and hence orthogonal to the established paradigm of Landau’s Fermi-liquid(FL). Such a sta...Orthogonal metal is a new quantum metallic state that conducts electricity but acquires no Fermi surface(FS)or quasiparticles, and hence orthogonal to the established paradigm of Landau’s Fermi-liquid(FL). Such a state may hold the key of understanding the perplexing experimental observations of quantum metals that are beyond FL, i.e., dubbed non-Fermi-liquid(nFL), ranging from the Cu-and Fe-based oxides, heavy fermion compounds to the recently discovered twisted graphene heterostructures. However, to fully understand such an exotic state of matter, at least theoretically, one would like to construct a lattice model and to solve it with unbiased quantum many-body machinery. Here we achieve this goal by designing a 2D lattice model comprised of fermionic and bosonic matter fields coupled with dynamic Z2 gauge fields, and obtain its exact properties with sign-free quantum Monte Carlo simulations. We find that as the bosonic matter fields become disordered, with the help of deconfinement of the Z2 gauge fields, the system reacts with changing its nature from the conventional normal metal with an FS to an orthogonal metal of n FL without FS and quasiparticles and yet still responds to magnetic probe like an FL. Such a quantum phase transition from a normal metal to an orthogonal metal, with its electronic and magnetic spectral properties revealed, is calling for the establishment of new paradigm of quantum metals and their transition with conventional ones.展开更多
We present broadband X-ray spectral analysis of the black hole X-ray binary MAXI J1348-630,performed using five AstroSat observations.The source was in the soft spectral state for the first three observations and in t...We present broadband X-ray spectral analysis of the black hole X-ray binary MAXI J1348-630,performed using five AstroSat observations.The source was in the soft spectral state for the first three observations and in the hard state for the last two.The three soft state spectra were modeled using a relativistic thin accretion disk with reflection features and thermal Comptonization.Joint fitting of the soft state spectra constrained the spin parameter of the black hole a_(*)>0.97 and the disk inclination angle i=32.9_(-0.6)^(+4.1)degrees.The bright and faint hard states had bolometric flux a factor of~6 and~10 less than that of the soft state respectively.Their spectra were fitted using the same model except that the inner disk radius was not assumed to be at the last stable orbit.However,the estimated values do not indicate large truncation radii and the inferred accretion rate in the disk was an order of magnitude lower than that of the soft state.Along with earlier reported temporal analysis,AstroS at data provide a comprehensive picture of the evolution of the source.展开更多
We present and analyze the variability of three Seyfert galaxies on intra-day timescales. We have analyzed in a uniform manner the 38 longest(> 30 ks) observations made for NGC 4051, MCG-06–30–15 and NGC 4151 by ...We present and analyze the variability of three Seyfert galaxies on intra-day timescales. We have analyzed in a uniform manner the 38 longest(> 30 ks) observations made for NGC 4051, MCG-06–30–15 and NGC 4151 by XMM-Newton between 2000 and 2015. The nuclei were quite active during essentially all of these observations and the overall X-ray fluxes(0.3–10 keV) varied by an order of magnitude. Most of the observations do appear to show characteristic timescales, estimated through their auto-correlation functions, ranging between ~2.9 ks and ~45.3 ks. The hard(2–10 keV) and soft(0.3–2.0 keV) bands are very well correlated but consideration of their hardness ratios shows that the sources typically soften during flares. We also provide new estimates of the central black hole masses for these three AGNs that support the hypothesis that Narrow Line Seyfert 1 galaxies have relatively small central black holes.展开更多
In recent years,great success has been achieved on the classification of symmetry-protected topological(SPT)phases for interacting fermion systems by using generalized cohomology theory.However,the explicit calculatio...In recent years,great success has been achieved on the classification of symmetry-protected topological(SPT)phases for interacting fermion systems by using generalized cohomology theory.However,the explicit calculation of generalized cohomology theory is extremely hard due to the difficulty of computing obstruction functions.Based on the physical picture of topological invariants and mathematical techniques in homotopy algebra,we develop an algorithm to resolve this hard problem.It is well known that cochains in the cohomology of the symmetry group,which are used to enumerate the SPT phases,can be expressed equivalently in different linear bases,known as the resolutions.By expressing the cochains in a reduced resolution containing much fewer basis than the choice commonly used in previous studies,the computational cost is drastically reduced.In particular,it reduces the computational cost for infinite discrete symmetry groups,like the wallpaper groups and space groups,from infinity to finity.As examples,we compute the classification of two-dimensional interacting fermionic SPT phases,for all 17 wallpaper symmetry groups.展开更多
We design generative neural networks that generate Monte Carlo configurations with complete absence of autocorrelation from which only short Markov chains are needed before making measurements for physical observables...We design generative neural networks that generate Monte Carlo configurations with complete absence of autocorrelation from which only short Markov chains are needed before making measurements for physical observables,irrespective of the system locating at the classical critical point,fermionic Mott insulator,Dirac semimetal,or quantum critical point.We further propose a network-initialized Monte Carlo scheme based on such neural networks,which provides independent samplings and can accelerate the Monte Carlo simulations by significantly reducing the thermalization process.We demonstrate the performance of our approach on the two-dimensional Ising and fermion Hubbard models,expect that it can systematically speed up the Monte Carlo simulations especially for the very challenging many-electron problems.展开更多
Symmetry-protected topological(SPT)phases—such as topological insulators and superconductors—are exotic quantum phases characterized by nontrivial edge states that are stable as long as certain symmetries are preser...Symmetry-protected topological(SPT)phases—such as topological insulators and superconductors—are exotic quantum phases characterized by nontrivial edge states that are stable as long as certain symmetries are preserved[1],[2],[3].Contrary to conventional wisdom,recent studies show that SPT phases can survive even when part of the protecting symmetry is locally broken by quenched disorder,provided that the symmetry is restored after ensemble averaging—a circumstance that defines a new class of topological phases dubbed average symmetry-protected topological(ASPT)phases[4],[5].展开更多
We investigate proton-antiproton(pp) pair production via photon-photon fusion in the ultra-peripheral collisions at the relativistic heavy ion collider(RHIC),employing a joint impact parameter and transverse momentum ...We investigate proton-antiproton(pp) pair production via photon-photon fusion in the ultra-peripheral collisions at the relativistic heavy ion collider(RHIC),employing a joint impact parameter and transverse momentum dependent formalism.We consider proton exchange,s-channel resonance,and hand-bag mechanisms,predicting differential distributions of pp production.Our theoretical predictions can be tested against future measurements at RHIC to enhance our understanding of photon-photon interactions in strong electromagnetic fields.展开更多
In this white paper,we present the potential of the enhanced X-ray timing and polarimetry(eXTP)mission to constrain the equation of state of dense matter in neutron stars,exploring regimes not directly accessible to t...In this white paper,we present the potential of the enhanced X-ray timing and polarimetry(eXTP)mission to constrain the equation of state of dense matter in neutron stars,exploring regimes not directly accessible to terrestrial experiments.By observing a diverse population of neutron stars—including isolated objects,X-ray bursters,and accreting systems—eXTP’s unique combination of timing,spectroscopy,and polarimetry enables high-precision measurements of compactness,spin,surface temperature,polarimetric signals,and timing irregularity.These multifaceted observations,combined with advances in theoretical modeling,pave the way toward a comprehensive description of the properties and phases of dense matter from the crust to the core of neutron stars.Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences,the eXTP mission is planned to be launched in early 2030.展开更多
In companion papers(A. Addazi, Nuovo Cim. C, 38(1): 21(2015); A. Addazi, Z. Berezhiani, and Y. Kamyshkov, ar Xiv:1607.00348), we have discussed current bounds on a new super-light baryo-photon, associated with a U(1)B...In companion papers(A. Addazi, Nuovo Cim. C, 38(1): 21(2015); A. Addazi, Z. Berezhiani, and Y. Kamyshkov, ar Xiv:1607.00348), we have discussed current bounds on a new super-light baryo-photon, associated with a U(1)B-L gauge, from current neutron-antineutron data, which are competitive with E¨otv¨os-type experiments.Here, we discuss the implications of possible baryo-photon detection in string theory and quantum gravity. The discovery of a very light gauge boson should imply violation of the weak gravity conjecture, carrying deep consequences for our understanding of holography, quantum gravity and black holes. We also show how the detection of a baryophoton would exclude the generation of all B-L violating operators from exotic stringy instantons. We will argue against the common statement in the literature that neutron-antineutron data may indirectly test at least the 300-1000 Te V scale. Searches for baryo-photons can provide indirect information on the Planck(or string) scale(quantum black holes, holography and non-perturbative stringy effects). This strongly motivates new neutron-antineutron experiments with adjustable magnetic fields dedicated to the detection of super-light baryo-photons.展开更多
We describe predictions for top quark pair differential distributions at hadron colliders,by combining the next-to-next-to-leading order quantum chromodynamics calculations and next-to-leading order electroweak correc...We describe predictions for top quark pair differential distributions at hadron colliders,by combining the next-to-next-to-leading order quantum chromodynamics calculations and next-to-leading order electroweak corrections with double resummation at the next-to-next-to-leading logarithmic accuracy of threshold logarithms and small-mass logarithms.To the best of our knowledge,this is the first study to present such a combination,which incorporates all known perturbative information.Numerical results are presented for the invariant-mass distribution,transverse-momentum distribution,and rapidity distributions.展开更多
We propose to deploy limits that arise from different tests of the Pauli Exclusion Principle： i） to provide theories of quantum gravity with experimental guidance; ii） to distinguish, among the plethora of possible...We propose to deploy limits that arise from different tests of the Pauli Exclusion Principle： i） to provide theories of quantum gravity with experimental guidance; ii） to distinguish, among the plethora of possible models, the ones that are already ruled out by current data; iii） to direct future attempts to be in accordance with experimental constraints. We first review experimental bounds on nuclear processes forbidden by the Pauli Exclusion Principle,which have been derived by several experimental collaborations making use of various detector materials. Distinct features of the experimental devices entail sensitivities on the constraints hitherto achieved that may differ from one another by several orders of magnitude. We show that with choices of these limits, well-known examples of flat noncommutative space-time instantiations of quantum gravity can be heavily constrained, and eventually ruled out.We devote particular attention to the analysis of the κ-Minkowski and θ-Minkowski noncommutative spacetimes.These are deeply connected to some scenarios in string theory, loop quantum gravity, and noncommutative geometry.We emphasize that the severe constraints on these quantum spacetimes, although they cannot rule out theories of top-down quantum gravity to which they are connected in various ways, provide a powerful limitation for those models. Focus on this will be necessary in the future.展开更多
The observation of the low-energyγ-ray(0.1 to 30 MeV)sky has been significantly limited since the COMPTEL instrument aboard the Compton Gamma Ray Observatory(CGRO)satellite was decommissioned in 2000.The exploration...The observation of the low-energyγ-ray(0.1 to 30 MeV)sky has been significantly limited since the COMPTEL instrument aboard the Compton Gamma Ray Observatory(CGRO)satellite was decommissioned in 2000.The exploration ofγ-ray photons within this energy band,often referred to as the MeV gap,is crucial to address numerous unresolved mysteries in high-energy and multi-messenger astrophysics.Although several large MeVγ-ray missions have been proposed(e.g.,e-ASTROGAM,AMEGO,and COSI),most of these are in the planning phase,with launches not expected until the next decade,at the earliest.Recently,there has been a surge in proposed CubeSat missions as cost-effective and rapidly implementable pathfinder alternatives.An MeV CubeSat dedicated toγ-ray astronomy could serve as a valuable demonstrator for large-scale future MeV payloads.This paper proposes aγ-ray payload design with a silicon-based tracker and a cesium iodide-based calorimeter.We report the results of a simulation study to assess the performance of this payload concept and compare the results with those of previousγ-ray instruments.As part of the performance assessment and comparison,we show that with our proposed payload design,a sensitivity better than IBIS can be achieved for energies between 0.1 and 10 MeV,and for energies up to around 1 MeV,the achieved sensitivity is comparable to COMPTEL,therefore opening up a window toward cost-effective observational astronomy with comparable performance to past missions.展开更多
In this paper we describe the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to accretion flows in the strong field gravity regime around both stellar-mass and supermassive bl...In this paper we describe the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to accretion flows in the strong field gravity regime around both stellar-mass and supermassive black-holes. eXTP has the unique capability of using advanced "spectral-timing-polarimetry" techniques to analyze the rapid variations with three orthogonal diagnostics of the flow and its geometry, yielding unprecedented insight into the inner accreting regions, the effects of strong field gravity on the material within them and the powerful outflows which are driven by the accretion process.展开更多
基金supported by the Croatian Science Foundation under the project number HRZZ-IP-2022-10-3878funding from the European Union’s Horizon Europe Research and Innovation programme under Grant Agreement No 101057511Funding Open access funding provided by CERN (European Organization for Nuclear Research).
文摘This study addresses a challenge of parametrizing a resolution function of a neutron beam from the neutron time of flight facility n_TOF at CERN.A difficulty stems from a fact that a resolution function exhibits rather strong variations in shape,over approximately ten orders of magnitude in neutron energy.To avoid a need for a manual identification of the appropri-ate analytical forms-hindering past attempts at its parametrization-we take advantage of the versatile machine learning techniques.Specifically,we parametrized it by training a multilayer feedforward neural network,relying on a key idea that such network acts as a universal approximator.The proof-of-concept is presented for a resolution function for the first experimental area of the n_TOF facility from the third phase of its operation.We propose an optimal network structure for a resolution function in question,which is also expected to be optimal or near-optimal for other experimental areas and for different phases of n_TOF operation.To reconstruct several resolution function forms in common use from a single para-metrized form,we provide a practical tool in the form of a specialized C++class encapsulating the computationally efficient procedures suited to the task.
基金supported by the National Key R&D Program of China(2022YFA1402702,2021YFA1401400,and 2022YFA1403402)the National Natural Science Foundation of China(12447103,12274289,12174068,and 12374144)+3 种基金the Innovation Program for Quantum Science and Technology(2021ZD0301902)the Science and Technology Commission of Shanghai Municipality(24LZ1400100,23JC1400600)support of Yangyang Development Fund,Shanghai Jiao Tong University 2030 Initiative,and startup funds from SJTUsupport of Shuguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission。
文摘The phenomenon of pseudogap and Fermi arcs has been a long-standing puzzle in the field of unconventional superconductivity(SC).Since first discovered in underdoped cuprates[1],the pseudogap has been generally identified in various(quasi)two-dimensional(2D)contexts,including thin-film FeSe[2],layered heavy fermion systems[3],magic angle twisted bilayer graphene[4],and recently even ultra-cold atoms[5].One prominent explanation for the pseudogap is hence to treat it as a precursor of pairing due to phase decoherence.
基金Supported by the National Key R&D Program of China(Grant No.2016YFA0300502)the National Science Foundation of China(Grant Nos.11574359 and 11674370)+2 种基金the Research Grants Council of Hong Kong SAR China under Grant Nos.17303019,C6026-16W,16324216,and 16307117the National Basic Research Program of China(Grant No.2015CB921700)the National Natural Science Foundation of China(Grant No.11874115).
文摘Orthogonal metal is a new quantum metallic state that conducts electricity but acquires no Fermi surface(FS)or quasiparticles, and hence orthogonal to the established paradigm of Landau’s Fermi-liquid(FL). Such a state may hold the key of understanding the perplexing experimental observations of quantum metals that are beyond FL, i.e., dubbed non-Fermi-liquid(nFL), ranging from the Cu-and Fe-based oxides, heavy fermion compounds to the recently discovered twisted graphene heterostructures. However, to fully understand such an exotic state of matter, at least theoretically, one would like to construct a lattice model and to solve it with unbiased quantum many-body machinery. Here we achieve this goal by designing a 2D lattice model comprised of fermionic and bosonic matter fields coupled with dynamic Z2 gauge fields, and obtain its exact properties with sign-free quantum Monte Carlo simulations. We find that as the bosonic matter fields become disordered, with the help of deconfinement of the Z2 gauge fields, the system reacts with changing its nature from the conventional normal metal with an FS to an orthogonal metal of n FL without FS and quasiparticles and yet still responds to magnetic probe like an FL. Such a quantum phase transition from a normal metal to an orthogonal metal, with its electronic and magnetic spectral properties revealed, is calling for the establishment of new paradigm of quantum metals and their transition with conventional ones.
基金support from the China Scholarship Council(CSC),Grant No.2020GXZ016647IUCAA Visitors Programme+1 种基金the Centre for Research,CHRIST(Deemed to be University)financial support in the form of a Seed Money Grant(SMSS-2217)。
文摘We present broadband X-ray spectral analysis of the black hole X-ray binary MAXI J1348-630,performed using five AstroSat observations.The source was in the soft spectral state for the first three observations and in the hard state for the last two.The three soft state spectra were modeled using a relativistic thin accretion disk with reflection features and thermal Comptonization.Joint fitting of the soft state spectra constrained the spin parameter of the black hole a_(*)>0.97 and the disk inclination angle i=32.9_(-0.6)^(+4.1)degrees.The bright and faint hard states had bolometric flux a factor of~6 and~10 less than that of the soft state respectively.Their spectra were fitted using the same model except that the inner disk radius was not assumed to be at the last stable orbit.However,the estimated values do not indicate large truncation radii and the inferred accretion rate in the disk was an order of magnitude lower than that of the soft state.Along with earlier reported temporal analysis,AstroS at data provide a comprehensive picture of the evolution of the source.
基金funded by ESA Member States and NASAsupport from the China Scholarship Council (CSC, Grant 2016GXZR89)+2 种基金supported by the Chinese Academy of Sciences (CAS) President’s International Fellowship Initiative (PIFI, Grant 2016VMB073)supported by the National Natural Science Foundation of China (Grant Nos. 11873073, 11473054 and U1531245)by the Science and Technology Commission of Shanghai Municipality (14ZR 1447100)
文摘We present and analyze the variability of three Seyfert galaxies on intra-day timescales. We have analyzed in a uniform manner the 38 longest(> 30 ks) observations made for NGC 4051, MCG-06–30–15 and NGC 4151 by XMM-Newton between 2000 and 2015. The nuclei were quite active during essentially all of these observations and the overall X-ray fluxes(0.3–10 keV) varied by an order of magnitude. Most of the observations do appear to show characteristic timescales, estimated through their auto-correlation functions, ranging between ~2.9 ks and ~45.3 ks. The hard(2–10 keV) and soft(0.3–2.0 keV) bands are very well correlated but consideration of their hardness ratios shows that the sources typically soften during flares. We also provide new estimates of the central black hole masses for these three AGNs that support the hypothesis that Narrow Line Seyfert 1 galaxies have relatively small central black holes.
基金Supported by the National Natural Science Foundation of China(Grant No.11874115)the Hong Kong Research Grants Council(Grant No.GRF 14306918)ANR/RGC Joint Research Scheme(Grant No.A-CUHK402/18)。
文摘In recent years,great success has been achieved on the classification of symmetry-protected topological(SPT)phases for interacting fermion systems by using generalized cohomology theory.However,the explicit calculation of generalized cohomology theory is extremely hard due to the difficulty of computing obstruction functions.Based on the physical picture of topological invariants and mathematical techniques in homotopy algebra,we develop an algorithm to resolve this hard problem.It is well known that cochains in the cohomology of the symmetry group,which are used to enumerate the SPT phases,can be expressed equivalently in different linear bases,known as the resolutions.By expressing the cochains in a reduced resolution containing much fewer basis than the choice commonly used in previous studies,the computational cost is drastically reduced.In particular,it reduces the computational cost for infinite discrete symmetry groups,like the wallpaper groups and space groups,from infinity to finity.As examples,we compute the classification of two-dimensional interacting fermionic SPT phases,for all 17 wallpaper symmetry groups.
基金support from the RGC of Hong Kong SAR of China(Grant Nos.17303019,17301420,17301721,and Ao E/P-701/20)the National Natural Science Foundation of China(Grant Nos.11974036,11874115,and 11834014)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000)the K.C.Wong Education Foundation(Grant No.GJTD-2020-01)supported by the Seed Funding“Quantum-Inspired explainable-AI”at the HKU-TCL Joint Research Centre for Artifcial Intelligence,Hong Kong。
文摘We design generative neural networks that generate Monte Carlo configurations with complete absence of autocorrelation from which only short Markov chains are needed before making measurements for physical observables,irrespective of the system locating at the classical critical point,fermionic Mott insulator,Dirac semimetal,or quantum critical point.We further propose a network-initialized Monte Carlo scheme based on such neural networks,which provides independent samplings and can accelerate the Monte Carlo simulations by significantly reducing the thermalization process.We demonstrate the performance of our approach on the two-dimensional Ising and fermion Hubbard models,expect that it can systematically speed up the Monte Carlo simulations especially for the very challenging many-electron problems.
基金the National Key R&D Program of China(2022YFA1403402)the National Natural Science Foundation of China(12174068)+3 种基金the Science and Technology Commission of Shanghai Municipality(24LZ1400100 and 23JC1400600)the Shuguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education CommissionJian-Hao Zhang and Zhen Bi are supported by startup funds from the Pennsylvania State UniversityZhen Bi also acknowledges support from NSF under award number DMR-2339319.
文摘Symmetry-protected topological(SPT)phases—such as topological insulators and superconductors—are exotic quantum phases characterized by nontrivial edge states that are stable as long as certain symmetries are preserved[1],[2],[3].Contrary to conventional wisdom,recent studies show that SPT phases can survive even when part of the protecting symmetry is locally broken by quenched disorder,provided that the symmetry is restored after ensemble averaging—a circumstance that defines a new class of topological phases dubbed average symmetry-protected topological(ASPT)phases[4],[5].
基金supported by the National Natural Science Foundation of China(Grant Nos.12275052,12147101,and 12405151).
文摘We investigate proton-antiproton(pp) pair production via photon-photon fusion in the ultra-peripheral collisions at the relativistic heavy ion collider(RHIC),employing a joint impact parameter and transverse momentum dependent formalism.We consider proton exchange,s-channel resonance,and hand-bag mechanisms,predicting differential distributions of pp production.Our theoretical predictions can be tested against future measurements at RHIC to enhance our understanding of photon-photon interactions in strong electromagnetic fields.
基金supported by China’s Space Origins Exploration Programsupported by the National Natural Science Foundation of China (Grant No.12273028)+36 种基金support from ERC Consolidator (Grant No.865768) AEONSsupport from NWO grant ENW-XL OCENW.XL21.XL21.038the support of the CNESsupported by the National Natural Science Foundation of China (Grant No.12333007)the International Partnership Program of Chinese Academy of Sciences (Grant No.113111KYSB20190020)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA15020100)supported by the China National Postdoctoral Program for Innovation Talents (Grant No.BX20240223)the China Postdoctoral Science Foundation Funded Project (Grant No.2024M761948)support from a Ramon y Cajal fellowship (Grant No.RYC2021-032718-I) financed by MCIN/AEI/10.13039/501100011033 and the European Union Next Generation EU/PRTRsupported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region (Grant No.2023D01E20)the National SKA Program of China (Grant No.2020SKA0120300)supported by the National Natural Science Foundation of China (Grant Nos.12033001,and 12473039)supported by Zhejiang Provincial Natural Science Foundation of China (Grant No.LQ24A030002)supported by the National Natural Science Foundation of China (Grant No.12003009)supported by the National SKA Program of China (Grant No.2020SKA0120200)the National Natural Science Foundation of China (Grant No.12041303)supported by the National Natural Science Foundation of China (Grant No.1227303)supported by the National SKA Program of China (Grant No.2020SKA0120300)the Beijing Natural Science Foundation (Grant No.1242018)the Max Planck Partner Group Program funded by the Max Planck Societysupported by JSPS KAKENHI (the Japan Society for the Promotion of Science,Grantsin-Aid for Scientific Research) (Grant Nos.23K19056,and 25K17403)supported by the National Natural Science Foundation of China (Grant No.12175109)support from FCT (Fundacao para a Ciência e a Tecnologia,I.P.,Portugal) (Grant Nos.UIDB/04564/2020,and 2022.06460.PTDC)supported from the program Unidad de Excelencia María de Maeztu CEX2020-001058-Mfrom the project PID2022-139427NB-I00 financed by the Spanish MCIN/AEI/10.13039/501100011033/FEDER,UE (FSE+)by the CRC-TR 211 “Strong-interaction matter under extreme conditions” -project Nr.315477589-TRR 211support from grant PID2021-124581OB-I0,PID2024-155316NB-I00,and 2021SGR00426supported by the National Natural Science Foundation of China (Grant No.12122513)supported in part by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant No.101020842)by the Deutsche Forschungsgemeinschaft (DFG,German Research Foundation)-Project-ID 279384907-SFB 1245support from the ERC Consolidator (Grant No.101002352) (LOVENEST)supported by the European Research Council (ERC) via the Consolidator Grant “MAGNESIA” (Grant No.817661)the Proof of Concept “Deep Space Pulse” (Grant No.101189496)the Catalan grant SGR2021-01269the Spanish grant ID2023-153099NA-I00the program Unidad de Excelencia Maria de Maeztu CEX2020-001058-Msupported by the Research Council of Finland (Grant No.354533).
文摘In this white paper,we present the potential of the enhanced X-ray timing and polarimetry(eXTP)mission to constrain the equation of state of dense matter in neutron stars,exploring regimes not directly accessible to terrestrial experiments.By observing a diverse population of neutron stars—including isolated objects,X-ray bursters,and accreting systems—eXTP’s unique combination of timing,spectroscopy,and polarimetry enables high-precision measurements of compactness,spin,surface temperature,polarimetric signals,and timing irregularity.These multifaceted observations,combined with advances in theoretical modeling,pave the way toward a comprehensive description of the properties and phases of dense matter from the crust to the core of neutron stars.Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Sciences,the eXTP mission is planned to be launched in early 2030.
文摘In companion papers(A. Addazi, Nuovo Cim. C, 38(1): 21(2015); A. Addazi, Z. Berezhiani, and Y. Kamyshkov, ar Xiv:1607.00348), we have discussed current bounds on a new super-light baryo-photon, associated with a U(1)B-L gauge, from current neutron-antineutron data, which are competitive with E¨otv¨os-type experiments.Here, we discuss the implications of possible baryo-photon detection in string theory and quantum gravity. The discovery of a very light gauge boson should imply violation of the weak gravity conjecture, carrying deep consequences for our understanding of holography, quantum gravity and black holes. We also show how the detection of a baryophoton would exclude the generation of all B-L violating operators from exotic stringy instantons. We will argue against the common statement in the literature that neutron-antineutron data may indirectly test at least the 300-1000 Te V scale. Searches for baryo-photons can provide indirect information on the Planck(or string) scale(quantum black holes, holography and non-perturbative stringy effects). This strongly motivates new neutron-antineutron experiments with adjustable magnetic fields dedicated to the detection of super-light baryo-photons.
文摘We describe predictions for top quark pair differential distributions at hadron colliders,by combining the next-to-next-to-leading order quantum chromodynamics calculations and next-to-leading order electroweak corrections with double resummation at the next-to-next-to-leading logarithmic accuracy of threshold logarithms and small-mass logarithms.To the best of our knowledge,this is the first study to present such a combination,which incorporates all known perturbative information.Numerical results are presented for the invariant-mass distribution,transverse-momentum distribution,and rapidity distributions.
文摘We propose to deploy limits that arise from different tests of the Pauli Exclusion Principle： i） to provide theories of quantum gravity with experimental guidance; ii） to distinguish, among the plethora of possible models, the ones that are already ruled out by current data; iii） to direct future attempts to be in accordance with experimental constraints. We first review experimental bounds on nuclear processes forbidden by the Pauli Exclusion Principle,which have been derived by several experimental collaborations making use of various detector materials. Distinct features of the experimental devices entail sensitivities on the constraints hitherto achieved that may differ from one another by several orders of magnitude. We show that with choices of these limits, well-known examples of flat noncommutative space-time instantiations of quantum gravity can be heavily constrained, and eventually ruled out.We devote particular attention to the analysis of the κ-Minkowski and θ-Minkowski noncommutative spacetimes.These are deeply connected to some scenarios in string theory, loop quantum gravity, and noncommutative geometry.We emphasize that the severe constraints on these quantum spacetimes, although they cannot rule out theories of top-down quantum gravity to which they are connected in various ways, provide a powerful limitation for those models. Focus on this will be necessary in the future.
基金supported by HKU-RMGS Funds (207300301 and 207301033principal investigator: Q.A.P.)+1 种基金The research of P.S.P. is partially supported by a General Research Fund (GRF) grant from the Research Grants Council of the Hong Kong Special Administrative Region, China (HKU Project 17304920principal investigator: S. C. Y. Ng).
文摘The observation of the low-energyγ-ray(0.1 to 30 MeV)sky has been significantly limited since the COMPTEL instrument aboard the Compton Gamma Ray Observatory(CGRO)satellite was decommissioned in 2000.The exploration ofγ-ray photons within this energy band,often referred to as the MeV gap,is crucial to address numerous unresolved mysteries in high-energy and multi-messenger astrophysics.Although several large MeVγ-ray missions have been proposed(e.g.,e-ASTROGAM,AMEGO,and COSI),most of these are in the planning phase,with launches not expected until the next decade,at the earliest.Recently,there has been a surge in proposed CubeSat missions as cost-effective and rapidly implementable pathfinder alternatives.An MeV CubeSat dedicated toγ-ray astronomy could serve as a valuable demonstrator for large-scale future MeV payloads.This paper proposes aγ-ray payload design with a silicon-based tracker and a cesium iodide-based calorimeter.We report the results of a simulation study to assess the performance of this payload concept and compare the results with those of previousγ-ray instruments.As part of the performance assessment and comparison,we show that with our proposed payload design,a sensitivity better than IBIS can be achieved for energies between 0.1 and 10 MeV,and for energies up to around 1 MeV,the achieved sensitivity is comparable to COMPTEL,therefore opening up a window toward cost-effective observational astronomy with comparable performance to past missions.
基金financial contribution from the agreement ASI-INAF n.2017-14-H.Osupport of the Chinese Academy of Sciences through the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA15020100)the Polish National Science Centre(Grant No.2013/10/M/ST9/00729)
文摘In this paper we describe the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to accretion flows in the strong field gravity regime around both stellar-mass and supermassive black-holes. eXTP has the unique capability of using advanced "spectral-timing-polarimetry" techniques to analyze the rapid variations with three orthogonal diagnostics of the flow and its geometry, yielding unprecedented insight into the inner accreting regions, the effects of strong field gravity on the material within them and the powerful outflows which are driven by the accretion process.
