The Z Zγtriple neutral gauge couplings are absent in the Standard Model(SM)at the tree level.They receive no contributions from dimension-6 effective operators,but can arise from effective operators of dimension-8.We...The Z Zγtriple neutral gauge couplings are absent in the Standard Model(SM)at the tree level.They receive no contributions from dimension-6 effective operators,but can arise from effective operators of dimension-8.We study the scale of new physics associated with such dimension-8 operators that can be probed by measuring the reaction e^+e^-→Zγ followed by Z→■■,vv decays,at future e^+e^- colliders including the CEPC,FCC-ee,ILC and CLIC.We demonstrate how angular distributions of the final-state mono-photon and leptons can play a key rôle in suppressing SM backgrounds.We further demonstrate that using electron/positron beam polarizations can significantly improve the signal sensitivities.We find that the dimension-8 new physics scale can be probed up to the multiTeV region at such lepton colliders.展开更多
Neutral triple gauge couplings(nTGCs)are absent in the standard model effective theory up to dimension-6 operators,but could arise from dimension-8 effective operators.In this work,we study the pure gauge operators of...Neutral triple gauge couplings(nTGCs)are absent in the standard model effective theory up to dimension-6 operators,but could arise from dimension-8 effective operators.In this work,we study the pure gauge operators of dimension-8 that contribute to nTGCs and are independent of the dimension-8 operator involving the Higgs doublet.We show that the pure gauge operators generate both ZγZ^*and Zγγ^*vertices with rapid energy dependence∝E^5,which can be probed sensitively via the reaction e^+e^-→Zγ.We demonstrate that measuring the nTGCs via the reaction e^+e^-→Zγfollowed by Z→qq decays can probe the new physics scales of dimension-8 pure gauge operators up to the range(1-5)TeV at the CEPC,FCC-ee and ILC colliders with s~(1/2)=(0.25-1)TeV,and up to the range(10-16)TeV at CLIC with s~(1/2)=(3-5)TeV,assuming in each case an integrated luminosity of 5 ab~(-1).We compare these sensitivities with the corresponding probes of the dimension-8 nTGC operators involving Higgs doublets and the dimension-8 fermionic contact operators that contribute to the e^+e^-Zγvertex.展开更多
基金The work of JE was supported in part by United Kingdom STFC Grant ST/P000258/1in part by the Estonian Research Council via a Mobilitas Pluss grant+5 种基金in part by the TDLI distinguished visiting fellow programmeThe work of HJH and RQX was supported in part by the National NSF of China(11675086,11835005)HJH is also supported in part by the CAS Center for Excellence in Particle Physics(CCEPP)the National Key R&D Program of China(2017YFA0402204)the Shanghai Laboratory for Particle Physics and Cosmology(11DZ2260700)the Office of Science and Technology,Shanghai Municipal Government(16DZ2260200)。
文摘The Z Zγtriple neutral gauge couplings are absent in the Standard Model(SM)at the tree level.They receive no contributions from dimension-6 effective operators,but can arise from effective operators of dimension-8.We study the scale of new physics associated with such dimension-8 operators that can be probed by measuring the reaction e^+e^-→Zγ followed by Z→■■,vv decays,at future e^+e^- colliders including the CEPC,FCC-ee,ILC and CLIC.We demonstrate how angular distributions of the final-state mono-photon and leptons can play a key rôle in suppressing SM backgrounds.We further demonstrate that using electron/positron beam polarizations can significantly improve the signal sensitivities.We find that the dimension-8 new physics scale can be probed up to the multiTeV region at such lepton colliders.
基金supported in part by United Kingdom STFC(Grant No.ST/P000258/1)in part by the Estonian Research Council via a Mobilitas Pluss grant+5 种基金in part by the TDLI distinguished visiting fellow programmesupported in part by the National Natural Science Foundation of China(Grant Nos.11675086,and 11835005)supported in part by the CAS Center for Excellence in Particle Physics(CCEPP)the National Key R&D Program of China(Grant No.2017YFA0402204)the Key Laboratory for Particle Physics,Astrophysics and Cosmology(Ministry of Education)the Office of Science and Technology,Shanghai Municipal Government(Grant No.16DZ2260200)。
文摘Neutral triple gauge couplings(nTGCs)are absent in the standard model effective theory up to dimension-6 operators,but could arise from dimension-8 effective operators.In this work,we study the pure gauge operators of dimension-8 that contribute to nTGCs and are independent of the dimension-8 operator involving the Higgs doublet.We show that the pure gauge operators generate both ZγZ^*and Zγγ^*vertices with rapid energy dependence∝E^5,which can be probed sensitively via the reaction e^+e^-→Zγ.We demonstrate that measuring the nTGCs via the reaction e^+e^-→Zγfollowed by Z→qq decays can probe the new physics scales of dimension-8 pure gauge operators up to the range(1-5)TeV at the CEPC,FCC-ee and ILC colliders with s~(1/2)=(0.25-1)TeV,and up to the range(10-16)TeV at CLIC with s~(1/2)=(3-5)TeV,assuming in each case an integrated luminosity of 5 ab~(-1).We compare these sensitivities with the corresponding probes of the dimension-8 nTGC operators involving Higgs doublets and the dimension-8 fermionic contact operators that contribute to the e^+e^-Zγvertex.
