We explored a new approach to search for a low-mass Z′particle through J/ψdecays by identifying its existence through parity-violating phenomena in the isospin-violating final states ofΛΣ¯^(0)and the correspo...We explored a new approach to search for a low-mass Z′particle through J/ψdecays by identifying its existence through parity-violating phenomena in the isospin-violating final states ofΛΣ¯^(0)and the corresponding charge conjugated states ofΛΣ¯^(0).Our investigation centered on a generation-independent and leptophobic Z′with mass below 10 GeV.Given the present experimental conditions at Beijing Spectrometer III(BESIII)and the anticipated opportunities at the Super Tau Charm Factory(STCF),we conducted Monte-Carlo simulations to predict possible events at both facilities.Notably,we foresee a substantial enhancement in the precision of the lower limit estimation ofαNP as well as a reduction in statistical uncertainty with upcoming STCF experiments.Furthermore,it is essential to highlight that a null result in the measurement ofαNP would impose stringent constraints,requiring the Z′−q−q couplings to be in the order of 10^(−2).展开更多
We study the decays ofΛb→Λ(→pπ^(−))ℓ^(+)ℓ^(−)withℓ=(e,μ,τ).We examine the full angular distributions with polarizedΛb,where the T-odd observables are identified.We discuss the possible effects of new physics(N...We study the decays ofΛb→Λ(→pπ^(−))ℓ^(+)ℓ^(−)withℓ=(e,μ,τ).We examine the full angular distributions with polarizedΛb,where the T-odd observables are identified.We discuss the possible effects of new physics(NP)and find that the T-odd observables are sensitive to them as they vanish in the standard model.Special attention is given to the interference of(pseudo)scalar operators with(axial)vector operators in polarized Λ_(b)→Λ(→pπ^(−))τ^(+)τ^(−),which are studied for the first time.Their effects are proportional to the lepton masses and therefore may evade the constraint from Λ_(b)→Λ(→pπ^(−))μ^(+)μ^(−) at the LHCb naturally.AsΛ_(b)→Λ(→pπ^(−))τ^(+)τ^(−) is uncontaminated by the charmonia resonance,it provides a clean background to probe NP.In addition,we show that the experimental central value of K10 in Λ_(b)→Λ(→pπ^(−))μ^(+)μ^(−) at the LHCb can be explained by the NP case,which couples to the right-handed quarks and leptons.The polarization fraction of Λ_(b) at the LHCb is found to be consistent with zero regardless of the NP scenarios.展开更多
Despite its success with mass spectra,the reputation of the bag model has been marred by embarrassment of the center of mass motion.It leads to severe theoretical inconsistencies.For instance,the masses and the decay ...Despite its success with mass spectra,the reputation of the bag model has been marred by embarrassment of the center of mass motion.It leads to severe theoretical inconsistencies.For instance,the masses and the decay constants would no longer be independent of the momentum.In this work,we provide a systematic approach to resolving this problem.Our framework can consistently compute the meson decay constants and baryon transition form factors.Notably,the form factors in the neutronβdecays do not depend on any free parameters and are determined to be F1V=1and F1A=1.31or F1A/F1V=1.31,which is close to the experimental value of F1A/F1V=1.27.In addition,we find that B(Λb→Λγ)=(6.8±3.3)×10-6,which agrees to the experimental value of(7.1±1.7)×10-6.展开更多
基金Supported in part by the National Key Research and Development Program of China under(2020YFC2201501)the National Natural Science Foundation of China(NSFC)(12347103,12205063)。
文摘We explored a new approach to search for a low-mass Z′particle through J/ψdecays by identifying its existence through parity-violating phenomena in the isospin-violating final states ofΛΣ¯^(0)and the corresponding charge conjugated states ofΛΣ¯^(0).Our investigation centered on a generation-independent and leptophobic Z′with mass below 10 GeV.Given the present experimental conditions at Beijing Spectrometer III(BESIII)and the anticipated opportunities at the Super Tau Charm Factory(STCF),we conducted Monte-Carlo simulations to predict possible events at both facilities.Notably,we foresee a substantial enhancement in the precision of the lower limit estimation ofαNP as well as a reduction in statistical uncertainty with upcoming STCF experiments.Furthermore,it is essential to highlight that a null result in the measurement ofαNP would impose stringent constraints,requiring the Z′−q−q couplings to be in the order of 10^(−2).
基金Supported in part by the National Key Research and Development Program of China (2020YFC2201501)the National Natural Science Foundation of China (NSFC) (12147103)。
文摘We study the decays ofΛb→Λ(→pπ^(−))ℓ^(+)ℓ^(−)withℓ=(e,μ,τ).We examine the full angular distributions with polarizedΛb,where the T-odd observables are identified.We discuss the possible effects of new physics(NP)and find that the T-odd observables are sensitive to them as they vanish in the standard model.Special attention is given to the interference of(pseudo)scalar operators with(axial)vector operators in polarized Λ_(b)→Λ(→pπ^(−))τ^(+)τ^(−),which are studied for the first time.Their effects are proportional to the lepton masses and therefore may evade the constraint from Λ_(b)→Λ(→pπ^(−))μ^(+)μ^(−) at the LHCb naturally.AsΛ_(b)→Λ(→pπ^(−))τ^(+)τ^(−) is uncontaminated by the charmonia resonance,it provides a clean background to probe NP.In addition,we show that the experimental central value of K10 in Λ_(b)→Λ(→pπ^(−))μ^(+)μ^(−) at the LHCb can be explained by the NP case,which couples to the right-handed quarks and leptons.The polarization fraction of Λ_(b) at the LHCb is found to be consistent with zero regardless of the NP scenarios.
文摘Despite its success with mass spectra,the reputation of the bag model has been marred by embarrassment of the center of mass motion.It leads to severe theoretical inconsistencies.For instance,the masses and the decay constants would no longer be independent of the momentum.In this work,we provide a systematic approach to resolving this problem.Our framework can consistently compute the meson decay constants and baryon transition form factors.Notably,the form factors in the neutronβdecays do not depend on any free parameters and are determined to be F1V=1and F1A=1.31or F1A/F1V=1.31,which is close to the experimental value of F1A/F1V=1.27.In addition,we find that B(Λb→Λγ)=(6.8±3.3)×10-6,which agrees to the experimental value of(7.1±1.7)×10-6.
