arXiv subjects

Hongguang Zhang

Publications and source records attributed to Hongguang Zhang.

39 records · Page 3Linked to original sources

arXiv2016

Dark Matter Search Results from the Commissioning Run of PandaX-II

We present the results of a search for WIMPs from the commissioning run of the PandaX-II experiment located at the China Jinping underground Laboratory. A WIMP search data set with an exposure of 306$\times$19.1 kg-day was taken, while its dominant $^{85}$Kr background was used as the electron recoil calibration. No WIMP candidates are identified, and a 90\% upper limit is set on the spin-independent elastic WIMP-nucleon cross section with a lowest excluded cross section of 2.97$\times$10$^{-45}$~cm$^2$ at a WIMP mass of 44.7~GeV/c$^2$.

hep-ex↗

arXiv2014

A c=1 phase transition in two-dimensional CDT/Horava-Lifshitz gravity?

We study matter with central charge $c >1$ coupled to two-dimensional (2d) quantum gravity, here represented as causal dynamical triangulations (CDT). 2d CDT is known to provide a regularization of (Euclidean) 2d Hořava-Lifshitz quantum gravity. The matter fields are massive Gaussian fields, where the mass is used to monitor the central charge $c$. Decreasing the mass we observe a higher order phase transition between an effective $c=0$ theory and a theory where $c>1$. In this sense the situation is somewhat similar to that observed for "standard" dynamical triangulations (DT) which provide a regularization of 2d quantum Liouville gravity. However, the geometric phase observed for $c >1$ in CDT is very different from the corresponding phase observed for DT.

gr-qc↗

arXiv2014

The spectral dimension in 2D CDT gravity coupled to scalar fields

Causal Dynamical Triangulations (CDT) provide a non-perturbative formulation of Quantum Gravity assuming the existence of a global time foliation. In our earlier study we analyzed the effect of including $d$ copies of a massless scalar field in the two-dimensional CDT model with imaginary time. For $d > 1$ we observed the formation of a "blob", somewhat similar to that observed in four-dimensional CDT without matter. In the two-dimensional case the "blob" has a Hausdorff dimension $D_H=3$. In this paper we study the spectral dimension $D_S$ of the two-dimensional CDT-universe, both for $d = 0$ (pure gravity) and $d = 4$. We show that in both cases the spectral dimension is consistent with $D_S = 2$.

gr-qc↗