Electron-positron colliders operating in the GeV center-of-mass range,or tau-charm energy region,have been proved to enable competitive frontier research due to several unique features.With the progress of high-energy...Electron-positron colliders operating in the GeV center-of-mass range,or tau-charm energy region,have been proved to enable competitive frontier research due to several unique features.With the progress of high-energy physics in the last two decades,a new-generation Tau-Charm factory,called the Super Tau-Charm Facility(STCF),has been actively promoted by the particle physics community in China.STCF has the potential to address fundamental questions such as the essence of color confinement and the matter-antimatter asymmetry within the next decades.The main design goals of the STCF are a center-of-mass energy ranging from 2 to 7 GeV and a luminosity surpassing 5×10^(34)cm^(−2)s^(−1)that is optimized at a center-of-mass energy of 4 GeV,which is approximately 50 times that of the currently operating Tau-Charm factory-BEPCII.The STCF accelerator has two main parts:a double-ring collider with a crab-waist collision scheme and an injector that provides top-up injections for both electron and positron beams.As a typical third-generation electron-positron circular collider,the STCF accelerator faces many challenges in both accelerator physics and technology.In this paper,the conceptual design of the STCF accelerator complex is presented,including the ongoing efforts and plans for technological research and develop-ment,as well as the required infrastructure.The STCF project aims to secure support from the Chinese central government for its construction during the 15th Five-Year Plan(2026-2030).展开更多
Based on the quark model the cross section for the e^(+)e^(-)→Z^(0)/r^(*)→Ω^(++)_(ccc)Ω^(--)_(ccc)exclusive process is investigated at the tree level.Compared with the Z^(0)→Ω^(-)Ω^(+)decay,our result shows tha...Based on the quark model the cross section for the e^(+)e^(-)→Z^(0)/r^(*)→Ω^(++)_(ccc)Ω^(--)_(ccc)exclusive process is investigated at the tree level.Compared with the Z^(0)→Ω^(-)Ω^(+)decay,our result shows that the Z^(0)boson favors decaying into charmed baryon pairs.The results are also compared with the calculation of inclusively charmed baryon production.展开更多
The measurement of decay parameters is one of the important goals of particle physics experiments,and the measurement serves as a probe to search for evidence of CP violation in baryonic decays.The experimental result...The measurement of decay parameters is one of the important goals of particle physics experiments,and the measurement serves as a probe to search for evidence of CP violation in baryonic decays.The experimental results will aid in advancing existing theoretical research and establishing new experimental objectives.In this study,we formulate the asymmetric parameters that characterize parity violation,and then derive formulas for the measurement of CP violation.The formulae for the joint angular distribution of the full decay chain as well as the polarization observable of Ξ^(0),Ξ¯^(0),Λ,and Λ¯are also provided for experiments.Lastly,we evaluated the sensitivity of two asymmetric parameters:αΞ0→Λπ0(abbreviated asαΞ0)andαΞ¯0→Λ¯γ(abbreviated asαΞ¯0)for future experimental measurements.展开更多
CP violation in baryonic decays has not been significantly observed.With large data events accumulated at e+e-colliders or the Large Hadron Collider,charmed baryon decays would provide a promising laboratory to test C...CP violation in baryonic decays has not been significantly observed.With large data events accumulated at e+e-colliders or the Large Hadron Collider,charmed baryon decays would provide a promising laboratory to test CP symmetry.In this study,we formulateΛ^(+)_(c)→ΦρandΛ^(+)_(c)→ωρdecays for the measurement of their asymmetry parameters in weak decays at the BESII or LHCb experiments.The polarization transfer is analyzed in the two processes of e+e-→Λ^(+)_(c)Λ^(-)_(c)andΛ^(o)_(b)→Λ^(+)_(c)π^(-),and the formulas for the joint angular distribution of these processes are provided.The sensitivity of the measurement of the asymmetry parameters of the above two decay processes is estimated for future experiments.展开更多
Measurements of decay asymmetry parameters of charmed baryons,e.g.,■,provide more data to test the W-emission and W-exchange mechanisms controlled by strong and weak interactions.Taking advantage of the spin polariza...Measurements of decay asymmetry parameters of charmed baryons,e.g.,■,provide more data to test the W-emission and W-exchange mechanisms controlled by strong and weak interactions.Taking advantage of the spin polarization in charmed baryon decays,we investigate the possibility to measure weak decay asymmetry parameters in thee^+e^-→■ process.We analyze the transverse polarization spontaneously produced in this process and the spin transfer in the subsequent■ decays.The sensitivity to measure the asymmetry parameters is estimated for the decay■→■.展开更多
Polarization transfer measurement plays an important role in the search for new physics processes incharmed baryon decays.The measurement of the A^(+)_(c)→pK^(-)π^(+) decay is suggested asaspinpolarimeter.A general ...Polarization transfer measurement plays an important role in the search for new physics processes incharmed baryon decays.The measurement of the A^(+)_(c)→pK^(-)π^(+) decay is suggested asaspinpolarimeter.A general description of the decay is developed using Euler angles,and the polarization parameters are derived.Its relationship with parity violation is found using the phenomenological amplitude model.A Monte-Carlo simulation is performed,and the results show that charmed baryon polarization iswell determined usingaset ofMonte-Carloevents with selected asymmetry parameters.The experimental measurement of these asymmetry parameters is suggested.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFA1602200)the National Natural Science Foundation of China(Nos.12341501 and 12405174)the Hefei Comprehensive National Science Center for the strong support on the STCF key technology research project.
文摘Electron-positron colliders operating in the GeV center-of-mass range,or tau-charm energy region,have been proved to enable competitive frontier research due to several unique features.With the progress of high-energy physics in the last two decades,a new-generation Tau-Charm factory,called the Super Tau-Charm Facility(STCF),has been actively promoted by the particle physics community in China.STCF has the potential to address fundamental questions such as the essence of color confinement and the matter-antimatter asymmetry within the next decades.The main design goals of the STCF are a center-of-mass energy ranging from 2 to 7 GeV and a luminosity surpassing 5×10^(34)cm^(−2)s^(−1)that is optimized at a center-of-mass energy of 4 GeV,which is approximately 50 times that of the currently operating Tau-Charm factory-BEPCII.The STCF accelerator has two main parts:a double-ring collider with a crab-waist collision scheme and an injector that provides top-up injections for both electron and positron beams.As a typical third-generation electron-positron circular collider,the STCF accelerator faces many challenges in both accelerator physics and technology.In this paper,the conceptual design of the STCF accelerator complex is presented,including the ongoing efforts and plans for technological research and develop-ment,as well as the required infrastructure.The STCF project aims to secure support from the Chinese central government for its construction during the 15th Five-Year Plan(2026-2030).
基金Supported by the National Natural Science Foundation of China under Grant Nos 11645002,11375205 and 11565006
文摘Based on the quark model the cross section for the e^(+)e^(-)→Z^(0)/r^(*)→Ω^(++)_(ccc)Ω^(--)_(ccc)exclusive process is investigated at the tree level.Compared with the Z^(0)→Ω^(-)Ω^(+)decay,our result shows that the Z^(0)boson favors decaying into charmed baryon pairs.The results are also compared with the calculation of inclusively charmed baryon production.
基金Supported by the National Natural Science Foundation of China(12175244,11875262,11805037,U1832121)National Key Research and Development Program of China(2020YFA0406301)。
文摘The measurement of decay parameters is one of the important goals of particle physics experiments,and the measurement serves as a probe to search for evidence of CP violation in baryonic decays.The experimental results will aid in advancing existing theoretical research and establishing new experimental objectives.In this study,we formulate the asymmetric parameters that characterize parity violation,and then derive formulas for the measurement of CP violation.The formulae for the joint angular distribution of the full decay chain as well as the polarization observable of Ξ^(0),Ξ¯^(0),Λ,and Λ¯are also provided for experiments.Lastly,we evaluated the sensitivity of two asymmetric parameters:αΞ0→Λπ0(abbreviated asαΞ0)andαΞ¯0→Λ¯γ(abbreviated asαΞ¯0)for future experimental measurements.
基金Supported by the National Natural Science Foundation of China(12175244,11875262,11805037,U1832121)the National Key Research and Development ProgramofChina(2020YFA0406301)。
文摘CP violation in baryonic decays has not been significantly observed.With large data events accumulated at e+e-colliders or the Large Hadron Collider,charmed baryon decays would provide a promising laboratory to test CP symmetry.In this study,we formulateΛ^(+)_(c)→ΦρandΛ^(+)_(c)→ωρdecays for the measurement of their asymmetry parameters in weak decays at the BESII or LHCb experiments.The polarization transfer is analyzed in the two processes of e+e-→Λ^(+)_(c)Λ^(-)_(c)andΛ^(o)_(b)→Λ^(+)_(c)π^(-),and the formulas for the joint angular distribution of these processes are provided.The sensitivity of the measurement of the asymmetry parameters of the above two decay processes is estimated for future experiments.
基金Supported by the National Natural Science Foundation of China(11875262,11805037,11705078)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1832121)+1 种基金Shanghai Pujiang Program(18PJ1401000)Open Research Program of Large Research Infrastructures(2017),Chinese Academy of Sciences
文摘Measurements of decay asymmetry parameters of charmed baryons,e.g.,■,provide more data to test the W-emission and W-exchange mechanisms controlled by strong and weak interactions.Taking advantage of the spin polarization in charmed baryon decays,we investigate the possibility to measure weak decay asymmetry parameters in thee^+e^-→■ process.We analyze the transverse polarization spontaneously produced in this process and the spin transfer in the subsequent■ decays.The sensitivity to measure the asymmetry parameters is estimated for the decay■→■.
基金Partly supported by the National Natural Science Foundation of China NSFC(11875262,11875115)Joint Large-Scale Scientific Facility Funds ofthe NSFC and Chinese Academy of Sciences(U2032110)。
文摘Polarization transfer measurement plays an important role in the search for new physics processes incharmed baryon decays.The measurement of the A^(+)_(c)→pK^(-)π^(+) decay is suggested asaspinpolarimeter.A general description of the decay is developed using Euler angles,and the polarization parameters are derived.Its relationship with parity violation is found using the phenomenological amplitude model.A Monte-Carlo simulation is performed,and the results show that charmed baryon polarization iswell determined usingaset ofMonte-Carloevents with selected asymmetry parameters.The experimental measurement of these asymmetry parameters is suggested.
