Optimizing Higgs factories by modifying the recoil mass

It is difficult to measure the $WW$-fusion Higgs production process ($e^+e^- \to \nu \bar{\nu} h$) at a lepton collider with a center of mass energy of 240-250 GeV due to its small rate and the large background from the Higgsstrahlung process with an invisible $Z$ ($e^+e^- \to hZ,\,Z\to \nu\bar{\nu}$). We construct a modified recoil mass variable, $m^p_{\rm recoil}$, defined using only the 3-momentum of the reconstructed Higgs particle, and show that it can better separate the $WW$-fusion and Higgsstrahlung events than the original recoil mass variable $m_{\rm recoil}$. Consequently, the $m^p_{\rm recoil}$ variable can be used to improve the overall precisions of the extracted Higgs couplings, in both the conventional framework and the effective-field-theory framework. We also explore the application of the $m^p_{\rm recoil}$ variable in the inclusive cross section measurements of the Higgsstrahlung process, while a quantitive analysis is left for future studies.Comment: 25 pages, 8 figure

Nonlinear Spinors as the Candidate of Dark Matter

In this paper, we discuss the equation of state for nonlinear spinor gases in the context of cosmology. The mean energy momentum tensor is similar to that of the prefect fluid, but an additional function of state $W$ is introduced to describe the nonlinear potential. The equation of state $w(a)\lesssim -1$ in the early universe is calculated, which provides a natural explanation for the negative pressure of dark matter and dark energy. $W$ may be also the main origin of the cosmological constant $\Lambda$. So the nonlinear spinor gases may be a candidate for dark matter and dark energy.Comment: 8 pages, no figure

Functions of State for Spinor Gas in General Relativity

The energy momentum tensor of perfect fluid is a simplified but successful model in astrophysics. In this paper, assuming the particles driven by gravity and moving along geodesics, we derived the functions of state in detail. The results show that, these functions have a little correction for the usual thermodynamics. The new functions naturally satisfy the causal condition and consist with relativity. For the self potentials of the particles we introduce an extra function $W$, which acts like negative pressure and can be used to describe dark matter. The results are helpful to understand the relation and interaction between space-time and matter.Comment: 13 pages, no figure. arXiv admin note: text overlap with arXiv:0708.296