The high-luminosity Superτ-Charm Factory(STCF)will be a crucial facility for charm-physics research,particularly for the precise measurement of electroweak parameters,measuring D^(0)-D^(-)^(0)mixing parameters,invest...The high-luminosity Superτ-Charm Factory(STCF)will be a crucial facility for charm-physics research,particularly for the precise measurement of electroweak parameters,measuring D^(0)-D^(-)^(0)mixing parameters,investigating conjugation–parity(CP)violation within the charm sector,searching for the rare and forbidden decays of charmed hadrons,and addressing other foundational questions related to charmed hadrons.With the world’s largest charm-threshold data,the STCF aims to achieve high sensitivity in studying the strong phase of neutral D mesons using quantum correlation,complementing studies at LHCb and Belle II,and contributing to the understanding of CP violations globally.The STCF will also enable world-leading precision in measuring the leptonic decays of charmed mesons and baryons,providing constraints on the Cabibbo–Kobayashi–Maskawa matrix and strong-force dynamics.Additionally,the STCF will explore charmed hadron spectroscopy.The advanced detector and clean experimental environment of the STCF will enable unprecedented precision,help address key challenges in the Standard Model,and facilitate the search for potential new physics.展开更多
The matter-antimatter asymmetry observed in nature is one of the biggest mysteries in physics,and the resolution of this puzzle could be one of the necessary paths to identifying the ultimate theory of the universe.Th...The matter-antimatter asymmetry observed in nature is one of the biggest mysteries in physics,and the resolution of this puzzle could be one of the necessary paths to identifying the ultimate theory of the universe.The violation of the combined charge-conjugation and parity(CP)symmetry is one of the required ingredients for explaining this asymmetry[1].展开更多
The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 3...The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.展开更多
In this study,the non-trival effect of the selection of reference particles for decay angle definitions is demonstrated when constructing the partial-wave amplitude of multi-body decays using helicity formalism.This i...In this study,the non-trival effect of the selection of reference particles for decay angle definitions is demonstrated when constructing the partial-wave amplitude of multi-body decays using helicity formalism.This issue is often ignored in the standard use case of helicity formalism.A new technique is proposed to test the selection of the particle ordering,and it can also be used as a generalized method to calculate the rotation operators that are used for the final-state alignment between different decay chains.Moreover,numerical validations are performed to support the arguments and to verify the effectiveness of the proposed technique.展开更多
文摘The high-luminosity Superτ-Charm Factory(STCF)will be a crucial facility for charm-physics research,particularly for the precise measurement of electroweak parameters,measuring D^(0)-D^(-)^(0)mixing parameters,investigating conjugation–parity(CP)violation within the charm sector,searching for the rare and forbidden decays of charmed hadrons,and addressing other foundational questions related to charmed hadrons.With the world’s largest charm-threshold data,the STCF aims to achieve high sensitivity in studying the strong phase of neutral D mesons using quantum correlation,complementing studies at LHCb and Belle II,and contributing to the understanding of CP violations globally.The STCF will also enable world-leading precision in measuring the leptonic decays of charmed mesons and baryons,providing constraints on the Cabibbo–Kobayashi–Maskawa matrix and strong-force dynamics.Additionally,the STCF will explore charmed hadron spectroscopy.The advanced detector and clean experimental environment of the STCF will enable unprecedented precision,help address key challenges in the Standard Model,and facilitate the search for potential new physics.
基金supported by the National Key R&D Program of China(2023YFA1609400,2020YFA0406400,and 2023YFA1606000)the National Natural Science Foundation of China(11935018,12221005,12422504,12105127,and 124B2097)the Fundamental Research Funds for the Central Universities,Lanzhou University(lzujbky-2021-ey09 and lzujbky-2023-it32).
文摘The matter-antimatter asymmetry observed in nature is one of the biggest mysteries in physics,and the resolution of this puzzle could be one of the necessary paths to identifying the ultimate theory of the universe.The violation of the combined charge-conjugation and parity(CP)symmetry is one of the required ingredients for explaining this asymmetry[1].
基金support from diverse funding sources,including the National Key Program for S&T Research and Development of the Ministry of Science and Technology(MOST),Yifang Wang's Science Studio of the Ten Thousand Talents Project,the CAS Key Foreign Cooperation Grant,the National Natural Science Foundation of China(NSFC)Beijing Municipal Science&Technology Commission,the CAS Focused Science Grant,the IHEP Innovation Grant,the CAS Lead Special Training Programthe CAS Center for Excellence in Particle Physics,the CAS International Partnership Program,and the CAS/SAFEA International Partnership Program for Creative Research Teams.
文摘The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.
基金This work was supported in part by National Key R&D Program of China(2017YFA0402103,2020YFA0406400)National Natural Science Foundation of China(11775122,11822506,11975015)Fundamental Research Funds for the Central Universities。
文摘In this study,the non-trival effect of the selection of reference particles for decay angle definitions is demonstrated when constructing the partial-wave amplitude of multi-body decays using helicity formalism.This issue is often ignored in the standard use case of helicity formalism.A new technique is proposed to test the selection of the particle ordering,and it can also be used as a generalized method to calculate the rotation operators that are used for the final-state alignment between different decay chains.Moreover,numerical validations are performed to support the arguments and to verify the effectiveness of the proposed technique.
