Searching for Charged Higgs Boson in Polarized Top Quark

The charged Higgs boson is quite common in many new physics models. In this study we examine the potential of observing a heavy charged Higgs boson in its decay mode of top-quark and bottom-quark in the Type-II Two-Higgs-Doublet-Model. In this model, the chirality structure of the coupling of charged Higgs boson to the top- and bottom-quark is very sensitive to the value of $\tan\beta$. As the polarization of the top-quark can be measured experimentally from the top-quark decay products, one could make use of the top-quark polarization to determine the value of $\tan\beta$. We preform a detailed analysis of measuring top-quark polarization in the production channels $gb\to tH^-$ and $g\bar{b}\to \bar{t}H^+$. We calculate the helicity amplitudes of the charged Higgs boson production and decay.Our calculation shows that the top-quark from the charged Higgs boson decay provides a good probe for measuring $\tan\beta$, especially for the intermediate $\tan\beta$ region. On the contrary, the top-quark produced in association with the charged Higgs boson cannot be used to measure $\tan\beta$ because its polarization is highly contaminated by the $t$-channel kinematics.Comment: 21 pages, 12 figures, 2 table

Fractional Path Integrals and its degeneration to Dimensional Regularization

In this work we study particles propagate in a fractional path and use fractional derivatives to extend the dynamic dimension of Quantum Field Theory. we construct the Lagrangian of fractional scalar, vector and spinor fields to obtain their propagators by path integral. Then we compute the typical tree level and one loop diagrams which correspond to QED cases. The calculations show the dimension dependence of amplitudes. Additionally, in one loop calculation we obtain results which are consistent with dimensional regularization as the dimension approaches to the Standard Model value. Therefore, the fractional Path Integrals can be regarded as an equivalent theoretical representation for regularizing the divergence in the normal Quantum Field Theory. We also derive the equation of motion for scalar, vector and spinor particles propagate in fractal paths and discuss the corresponding gauge symmetry, where we find a special non-local gauge transformation.Comment: 17page

CPCP violation phase and decomposition relations in Higgs BSM amplitudes

We define a $CP$ violation phase angle $\xi$ to quantify the mixture of $CP$-even and $CP$-odd states for Higgs boson in new physics beyond Standard Model (BSM) firstly, and then show it explicitly in $H\to\gamma\gamma$, $H\to\gamma\ell\ell$ and $H\to 4\ell$ amplitudes. The analytical form gives a good explanation why the $CP$ violation phase could be observed and the interference between $CP$-even and $CP$-odd parts exist in $H\to 4\ell$ process, but not in $H\to\gamma\gamma$ and $H\to\gamma\ell\ell$ processes. To understand the analytical structure of these BSM amplitudes, we introduce a new method of decomposing $H\to\gamma\ell\ell$ and $H\to 4\ell$ amplitudes into $H\to\gamma\gamma$ amplitudes. For a comparison, by using the on-shell scattering amplitude approach we study the recursion relations of amplitudes and get a consistent result independently.Comment: 19 pages, 7 figure

The Study on In-City Capacity Affected by Pedestrian Crossing

Currently, the urban road traffic congestion is serious and the traffic accident is happening at a high frequency; thus it has not satisfied the travel needs of security and affects the quality of urban trips. In order to effectively relieve the confliction of people and motor vehicle, to make sure of the safety of pedestrians crossing the road, and to improve the capacity of urban roads, this passage focuses on studying the influence of pedestrians crossing the roads on the capacity of urban roads in three pedestrian crossing approaches including freely crossing the street, uncontrolled crossing of the pedestrian crosswalk, and controlled crossing of the pedestrian crosswalk. Firstly, it confirms the general formula of the road capacity when pedestrians are crossing the road based on three preassumptions, combined with the survey data, and then constructs the empirical mathematical model of pedestrian crossing on the capacity impact. Lastly, it takes the step of case calculation and simulation evaluation and calculates errors between them, finding that the error between the model calculation and software simulation is small. The efficiency of the model is validated and improved