Guangzhou as livable city: Its origin, inheritance, and development

This article intends to explore the ideas and concepts that dominate the landmark versions of planning in a historical survey on the development of urban planning for the construction of Guangzhou. From the Late 17th C. to the Mid-19th C. Xiguan in Guangzhou witnessed the booming of the Thirteen-hong characterized by gardens and buildings in Western architectural styles. These characteristics constituted the architectural features and urban spatial patterns on both sides of the Pearl River, and caused the moving westward of the ancient city center to the Thirteen-hong Business District. After The Second Opium War Western merchants began their planning and construction of Shameen with Western planning techniques, which, together with the model of the Thirteen-hong, led to the urban modernization of Guangzhou urban planning. During the years from 1911 to 1948, the urban planning and construction in Guangzhou underwent a sequence of processes from simplicity to complexity, and from part to whole. There was also a process from the simple imitation of Western ideas and concepts of urban planning in Dashatou Island to the renovation of Guangzhou urban planning marked with road and park construction, This process includes the dismantle of the city walls for road construction in 1912, the prelude of modern urban planning of Guangzhou in 1914, the planning for network and city-round road and park construction in 1918, the idea of “Traffic First” in 1921, the regional studies and planning in 1923, the concept of functional division in 1932, the idea of implementing urban function division in 1920s and 1930s, and the transference from the initial techniques and measures to land management in 1937. After that there was the adoption of the "zonal cluster layout" along the Pearl River in 1984, the idea of the Planning of Urban Agglomeration of the Pearl River Delta in 1995, and the continuation of the “four land usage modes” in 2003. The idea and concept of urban planning for Guangzhou, thus derived localized from the practice of Western urban planning in the Thirteen-hong and Shameen, later underwent the municipal planning of Dashatou, the idyllic residential districts. The innovated regional green space in 2006, followed by the livable urban and rural planning in 2016, and up to the lately ecological city in 2018, all bear the marks of the early ideas and concepts realized in the Thirteen-hong, Shameen, and Dashatou. Therefore, it can be further concluded that the urban planning of Guangzhou, developed from the initial function of landscape beautification to the regulation of regional green environment of the Pearl River Delta, underwent finally a full process of imitation, learning, transformation, and innovation, resulting in an idea of green, open, and shared urban construction

Sensitivity of the future e−p\boldsymbol{e^{-}p} collider to the coupling of axion-like particles with vector bosons

Axion-like particles (ALPs) arise naturally in many extensions of the Standard Model (SM). We explore the discovery potential for ALPs of the Large Hadron electron Collider (LHeC) via the $W^{+}W^{-}$ fusion process. For concreteness, both cases of the ALP decaying to muon pairs and $b\overline{b}$ pairs are investigated. Our numerical results show that the LHeC with the center of mass energy of $1.3$ TeV and the integrated luminosity of $1$ ab$^{-1}$ might be more sensitive than the LHC in probing ALPs over a range of masses from a few tens of GeV to $900$ GeV, where the promising sensitivities to the coupling of ALP with $W^{\pm}$ bosons reach nearly $0.15$ TeV$^{-1}$ and $0.32$ TeV$^{-1}$ for the signal processes $e^{-}p\rightarrow\nu_{e}ja(a\rightarrow\mu^{+}\mu^{-})$ and $e^{-}p\rightarrow\nu_{e}ja(a\rightarrow b\overline{b})$, respectively.Comment: 16 pages, 7 figure

Top quark rare three-body decays in the littlest Higgs model with T-parity

In the littlest Higgs model with T-parity (LHT), the mirror quarks have flavor structures and will contribute to the top quark flavor changing neutral current. In this work, we perform an extensive investigation of the top quark rare three-body decays $t\to cVV (V=\gamma,Z,g)$ and $t\to cf\bar{f} (f=b,\tau,\mu,e)$ at one-loop level. Our results show that the branching ratios of $t\to cgg$ and $t\to cb\bar{b}$ could reach $\mathcal {O}(10^{-3})$ in the favorite parameter space of the littlest Higgs model with T-parity, which implies that these decays may be detectable at the LHC or ILC, while for the other decays, their rates are too small to be observable at the present or future colliders.Comment: 12 pages, 10 figure

New gauge bosons from the littlest Higgs model and the process e+e−→ttˉe^{+}e^{-}\to t\bar{t}

In the context of the littlest Higgs$(LH)$ model, we study the process $e^{+}e^{-}\to t\bar{t}$. We find that the new gauge bosons $Z_{H}$ and $B_{H}$ can produce significant correction effects on this process, which can be further enhanced by the suitably polarized beams. In most of the parameter space preferred by the electroweak precision data, the absolute value of the relative correction parameter $R_{B_{H}}$ is larger than 5%. As long as $1TeV\leq M_{Z_{H}}\leq 1.5TeV$ and $0.3\leq c\leq 0.5,$ the absolute value of the relative correction parameter $R_{Z_{H}}$ is larger than 5%. With reasonable values of the parameters of the $LH$ model, the possible signals of the new gauge bosons $B_{H}$ and $Z_{H}$ can be detected via the process $e^{+}e^{-} \to t\bar{t}$ in the future $LC$ experiments with the c.m. energy $\sqrt{S}=800GeV$. $B_{H}$ exchange and $Z_{H}$ exchange can generate significantly corrections to the forward-backward asymmetry $A_{FB}(t\bar{t})$ only in small part of the parameter space.Comment: 18 pages, 6 figure

The top quark rare decays with flavor violation

In the present study, we investigate the decays of the top quark $t\rightarrow c\gamma$, $t\rightarrow cg$, $t\rightarrow cZ$ and $t\rightarrow ch$. They are extremely rare processes in the Standard Model (SM). As the $U(1)_X$ extension of the minimal supersymmetric standard model, the $U(1)_X$SSM features new superfields such as the right-handed neutrinos and three Higgs singlet states. We analyze the effects of different sensitivity parameters on the results and make reasonable theorecial predictions useful for future experimental developments. Considering the constraint of the updated experimental data, the numerical results show that the branching ratios of all four processes $t\rightarrow c\gamma,~cg,~cZ,~ch$ can reach the same order of magnitude as their experimental upper limits. Among them, $\tan\beta$ has the most obvious effect on each process and is the main parameter. $g_X$, $g_{YX}$, $\mu$, $M_2$, $\lambda_H$, $M_{U23}^2$ and $M_{Q23}^2$ are important parameters for the processes, and have effects on the numerical results.Comment: pages 22, figures 1

Single production of charged gauge bosons from little Higgs models in association with top quark at the LHCLHC

In the context of the little Higgs models, we discuss single production of the new charged gauge bosons in association with top quark at the $CERN$ Large Hadron Collider$(LHC)$. We find that the new charged gauge bosons $W_{H}^{-}$ and $X^{-}$, which are predicted by the littlest Higgs model and the SU(3) simple model, respectively, can be abundantly produced at the $LHC$. However, since the main backgrounds coming from the processes $pp\to t\bar{t}+X$ and $pp\to tW^{-}+X$ are very large, the values of the ratios $N_{W}$ and $N_{X}$ are very small in most of the parameter space. It is only possible to detect the signal of the gauge boson $W_{H}^{-}$ via the process $pp\to gb+X\to tW_{H}^{-}+X$ at the $LHC$ in a small region of the parameter space.Comment: 14pages, 4 figures. To be published in Europhysics Letter

The effects of the little Higgs models on ttˉh0t\bar{t} h^0 production via γγ\gamma \gamma collision at linear colliders

In the frameworks of the littlest Higgs($LH$) model and its extension with T-parity($LHT$), we studied the associated $t\bar th^0$ production process $e^+ e^- \to \gamma\gamma \to t \bar t h^0$ at the future $e^+e^-$ linear colliders up to QCD next-to-leading order. We present the regions of $\sqrt{s}-f$ parameter space in which the $LH$ and $LHT$ effects can and cannot be discovered with the criteria assumed in this paper. The production rates of process $\gamma\gamma \to t \bar t h^0$ in different photon polarization collision modes are also discussed. We conclude that one could observe the effects contributed by the $LH$ or $LHT$ model on the cross section for the process $e^+ e^- \to \gamma\gamma \to t \bar t h^0$ in a reasonable parameter space, or might put more stringent constraints on the $LH$/$LHT$ parameters in the future experiments at linear colliders.Comment: 22 pages, 25 figures, version to appear in Phys. Rev.

Top quark chromomagnetic dipole moment in the littlest Higgs model with T-parity

The littlest Higgs model with T-parity, which is called $LHT$ model, predicts the existence of the new particles, such as heavy top quark, heavy gauge bosons, and mirror fermions. We calculate the one-loop contributions of these new particles to the top quark chromomagnetic dipole moment $(CMDM)$ $\Delta K$. We find that the contribution of the $LHT$ model is one order of magnitude smaller than the standard model prediction value.Comment: latex files, 12 pages, 3 figure

Higgs search and flavor-safe fermion mass generation

We study a scenario of electroweak symmetry breaking where the weak gauge boson masses arises significantly from a fermiophobic source. To minimize flavor violation, the fermion mass generation is still due to one light doublet scalar. One of the realizations is the Bosonic Technicolor model. In these scenarios, the Yukawa couplings between the light scalar and the standard model fermions are in general enhanced while the couplings between the light scalar and weak gauge bosons are reduced. Even though the flavor violation induced by the neutral scalar at the tree level can be avoided, the charged scalar state inevitably mediate flavor changing neutral current processes. With the enhancement in the Yukawa couplings, one expects serious constraints of such models from flavor violating effects. We find that the most severe bound comes from neutral meson mixing of $B^{0}_{d}-\bar{B^{0}_{d}}$. Large parameter space is excluded if the weak gauge boson mass generation is dominated by the fermophobic sector. However, the correlation between the Yukawa coupling and charged scalar mass show that a factor of two enhancement in top Yukawa coupling is still allowed for charged scalar heavier than 500 GeV. We use this as a benchmark point to study the phenomenology of the light scalar. It is interesting that the destructive interference between the top quark loop and the $W$-boson loop in the di-photon channel becomes significant and makes the channel negligible. In the light scalar region, the search becomes much more challenging than the conventional SM Higgs boson.Comment: 13 pages, 3 figure