Particles and fields|5 Article(s)
Measurements of decay branching fractions of in associated production at the CEPC *
Bai Yu, Chen Chun-Hui, Fang Ya-Quan, Li Gang, Ruan Man-Qi, Shi Jing-Yuan, Wang Bo, Kong Pan-Yu, Lan Bo-Yang, and Liu Zhan-Feng
The high-precision measurement of Higgs boson properties is one of the primary goals of the Circular Electron Positron Collider (CEPC). The measurements of decay branching fraction in the CEPC experiment is presented, considering a scenario of analysing 5000 fb-1 collision data with the center-of-mass energy of 250 GeV. In this study the Higgs bosons are produced in association with a pair of leptons, dominantly mediated by the ZH production process. The statistical uncertainty of the signal cross section is estimated to be about 1% in the final state, and approximately 5%-10% in the final states. In addition, the main sources of the systematic uncertainties and their impacts to the measurements of branching fractions are discussed. This study demonstrates the potential of precise measurement of the hadronic final states of the Higgs boson decay at the CEPC, and will provide key information to understand the Yukawa couplings between the Higgs boson and quarks, which are predicted to be the origin of quarks’ masses in the standard model.
Chinese Physics C
  • Publication Date: Jan. 01, 1900
  • Vol.44 Issue, 1 (2020)
The semileptonic decay within the LCSR approach under heavy quark effective field theory *
Zhou Rui-Yu, Guo Lei, Fu Hai-Bing, Cheng Wei, and Wu Xing-Gang
The heavy quark effective field theory (HQEFT) provides an effective way to deal with heavy meson decays. In this paper, we adopt two different correlators to derive the light-cone sum rules (LCSR) for the transition form factors (TFFs) in the framework of HQEFT. We label the two LCSR results as LCSR- and LCSR- , which stand for the conventional correlator and the right-handed correlator. We observe that the correlation parameter for the branching ratio is , implying a consistency of LCSRs with the other correlators. Furthermore, we obtain and . We also obtain and , both of which agree with the lattice QCD predictions. Thus, HQEFT provides a useful framework for studying B meson decays. Moreover, by using the right-handed correlator, the twist-2 terms are dominant in TFF , as their contribution is over ~97% in the whole region, while the large twist-3 uncertainty of the conventional correlator is greatly suppressed. Hence, the LCSR- predictions can be used to test the properties of the various models for the pion twist-2 distribution amplitudes.
Chinese Physics C
  • Publication Date: Jan. 01, 1900
  • Vol.44 Issue, 1 (2020)
Mass spectra and wave functions of the doubly heavy baryons with JP=1+ heavy diquark cores *
Li Qiang, Chang Chao-Hsi, Qin Si-Xue, and Wang Guo-Li
Chinese Physics C
  • Publication Date: Jan. 01, 1900
  • Vol.44 Issue, 1 (2020)
A holographic description of theta-dependent Yang-Mills theory at finite temperature *
Li Si-Wen
Theta-dependent gauge theories can be studied using holographic duality through string theory in certain spacetimes. By this correspondence we consider a stack of N0 dynamical D0-branes as D-instantons in the background sourced by Nc coincident non-extreme black D4-branes. According to the gauge-gravity duality, this D0-D4 brane system corresponds to Yang-Mills theory with a theta angle at finite temperature. We solve the IIA supergravity action by taking account into a sufficiently small backreaction of the Dinstantons and obtain an analytical solution for our D0-D4-brane configuration. Subsequently, the dual theory in the large Nc limit can be holographically investigated with the gravity solution. In the dual field theory, we find that the coupling constant exhibits asymptotic freedom, as is expected in QCD. The contribution of the theta-dependence to the free energy gets suppressed at high temperatures, which is basically consistent with the calculation using the Yang-Mills instanton. The topological susceptibility in the large Nc limit vanishes, and this behavior remarkably agrees with the implications from the simulation results at finite temperature. Moreover, we finally find a geometrical interpretation of the theta-dependence in this holographic system.
Chinese Physics C
  • Publication Date: Jan. 01, 1900
  • Vol.44 Issue, 1 013103 (2020)