A Note on Noncommutative Brane Inflation

In this paper, we investigate the noncommutative KKLMMT D3/anti-D3 brane inflation scenario in detail. Incorporation of the brane inflation scenario and the noncommutative inflation scenario can nicely explain the large negative running of the spectral index as indicated by WMAP three-year data and can significantly release the fine-tuning for the parameter $\beta$. Using the WMAP three year results (blue-tilted spectral index with large negative running), we explore the parameter space and give the constraints and predictions for the inflationary parameters and cosmological observables in this scenario. We show that this scenario predicts a quite large tensor/scalar ratio and what is more, a too large cosmic string tension (assuming that the string coupling $g_s$ is in its likely range from 0.1 to 1) to be compatible with the present observational bound. A more detailed analysis reveals that this model has some inconsistencies according to the fit to WMAP three year results.Comment: 20 pages, 5 figures; accepted for publication in JCA

Search for Light Weakly-Interacting-Massive-Particle Dark Matter by Annual Modulation Analysis with a Point-Contact Germanium Detector at the China Jinping Underground Laboratory

We present results on light weakly interacting massive particle (WIMP) searches with annual modulation (AM) analysis on data from a 1-kg mass $p$-type point-contact germanium detector of the CDEX-1B experiment at the China Jinping Underground Laboratory. Datasets with a total live time of 3.2 yr within a 4.2 yr span are analyzed with analysis threshold of 250 eVee. Limits on WIMP-nucleus (${\chi}$-$N$) spin-independent cross sections as function of WIMP mass ($m_{\chi}$) at 90\% confidence level (C.L.) are derived using the dark matter halo model. Within the context of the standard halo model, the 90\% C.L. allowed regions implied by the DAMA/LIBRA and CoGeNT AM-based analysis are excluded at $>$99.99\% and 98\% C.L., respectively. These results correspond to the best sensitivity at $m_{\chi}$$<$6$~{\rm GeV}/c^2$ among WIMP AM measurements to date.Comment: 5 pages, 4 figure

Constraints on Spin-Independent Nucleus Scattering with sub-GeV Weakly Interacting Massive Particle Dark Matter from the CDEX-1B Experiment at the China Jin-Ping Laboratory

We report results on the searches of weakly interacting massive particles (WIMPs) with sub-GeV masses ($m_{\chi}$) via WIMP-nucleus spin-independent scattering with Migdal effect incorporated. Analysis on time-integrated (TI) and annual modulation (AM) effects on CDEX-1B data are performed, with 737.1 kg$\cdot$day exposure and 160 eVee threshold for TI analysis, and 1107.5 kg$\cdot$day exposure and 250 eVee threshold for AM analysis. The sensitive windows in $m_{\chi}$ are expanded by an order of magnitude to lower DM masses with Migdal effect incorporated. New limits on $\sigma_{\chi N}^{\rm SI}$ at 90\% confidence level are derived as $2\times$10$^{-32}\sim7\times$10$^{-35}$ $\rm cm^2$ for TI analysis at $m_{\chi}\sim$ 50$-$180 MeV/$c^2$, and $3\times$10$^{-32}\sim9\times$10$^{-38}$ $\rm cm^2$ for AM analysis at $m_{\chi}\sim$75 MeV/$c^2-$3.0 GeV/$c^2$.Comment: 5 pages, 4 figure

Constraints on Sub-GeV Dark Matter--Electron Scattering from the CDEX-10 Experiment

We present improved germanium-based constraints on sub-GeV dark matter via dark matter--electron ($\chi$-$e$) scattering using the 205.4 kg$\cdot$day dataset from the CDEX-10 experiment. Using a novel calculation technique, we attain predicted $\chi$-$e$ scattering spectra observable in high-purity germanium detectors. In the heavy mediator scenario, our results achieve 3 orders of magnitude of improvement for $m_{\chi}$ larger than 80 MeV/c$^2$ compared to previous germanium-based $\chi$-$e$ results. We also present the most stringent $\chi$-$e$ cross-section limit to date among experiments using solid-state detectors for $m_{\chi}$ larger than 90 MeV/c$^2$ with heavy mediators and $m_{\chi}$ larger than 100 MeV/c$^2$ with electric dipole coupling. The result proves the feasibility and demonstrates the vast potential of a new $\chi$-$e$ detection method with high-purity germanium detectors in ultralow radioactive background.Comment: 6 pages, 3 figures. Version updated to match PRL versio

Exotic Dark Matter Search with CDEX-10 Experiment at China Jinping Underground Laboratory

A search for exotic dark matter (DM) in the sub-GeV mass range has been conducted using 205 kg$\cdot$day data taken from a p-type point contact germanium detector of CDEX-10 experiment at China Jinping underground laboratory. New low-mass dark matter searching channels, neutral current fermionic DM absorption ($\chi+A\rightarrow \nu+A$) and DM-nucleus 3$\rightarrow$2 scattering ($\chi+\chi+A\rightarrow \phi+A$), have been analyzed with an energy threshold of 160 eVee. No significant signal was found. Thus new limits on the DM-nucleon interaction cross section are set for both models at sub-GeV DM mass region. A cross section limit for the fermionic DM absorption is set to be $\rm 2.5\times 10^{-46} cm^2$(90\% C.L.) at DM mass of 10 MeV/c$^2$. For the DM-nucleus 3$\rightarrow$2 scattering scenario, limits are extended to DM mass of 5 MeV/c$^2$ and 14 MeV/c$^2$ for the massless dark photon and bound DM final state, respectively.Comment: 5 pages, 7 figure

Curvaton Dynamics in Brane-worlds

We study the curvaton dynamics in brane-world cosmologies. Assuming that the inflaton field survives without decay after the end of inflation, we apply the curvaton reheating mechanism to Randall-Sundrum and to its curvature corrections: Gauss-Bonnet, induced gravity and combined Gauss-Bonnet and induced gravity cosmological models. In the case of chaotic inflation and requiring suppression of possible short-wavelength generated gravitational waves, we constraint the parameters of a successful curvaton brane-world cosmological model. If density perturbations are also generated by the curvaton field then, the fundamental five-dimensional mass could be much lower than the Planck massComment: 47 pages, 1 figure, references added, to be published in JCA

Search for exotic neutrino interactions using solar neutrinos in the CDEX-10 experiment

We investigate the exotic neutrino interactions using the 205.4 kg day exposure dataset of the CDEX-10 experiment at the China Jinping Underground Laboratory. New constraints on the mass and couplings of extra gauge boson are presented. The results are interpreted in two physics scenarios including an $U(1)_{B-L}$ gauge boson induced interaction between active neutrinos and electron/nucleus, and a dark photon induced the interaction between sterile neutrino and electron/nucleus where the dark photon couples to the Standard Model particles through kinetic mixing with the photon. This work probes new parameter space involving sterile neutrino coupling with dark photon with masses below 1 eV$/c^2$ at some typical choice of $\Delta m_{41}^{2}$ and $g^{\prime2}{\rm{sin}}^{2}2\theta_{14}$, which was previously unexplored by dark matter direct detection experiments and neutrino experiments.Comment: 6 pages, 3 figure

The type 2C phosphatase Wip1: An oncogenic regulator of tumor suppressor and DNA damage response pathways

The Wild-type p53-induced phosphatase 1, Wip1 (or PPM1D), is unusual in that it is a serine/threonine phosphatase with oncogenic activity. A member of the type 2C phosphatases (PP2Cδ), Wip1 has been shown to be amplified and overexpressed in multiple human cancer types, including breast and ovarian carcinomas. In rodent primary fibroblast transformation assays, Wip1 cooperates with known oncogenes to induce transformed foci. The recent identification of target proteins that are dephosphorylated by Wip1 has provided mechanistic insights into its oncogenic functions. Wip1 acts as a homeostatic regulator of the DNA damage response by dephosphorylating proteins that are substrates of both ATM and ATR, important DNA damage sensor kinases. Wip1 also suppresses the activity of multiple tumor suppressors, including p53, ATM, p16INK4a and ARF. We present evidence that the suppression of p53, p38 MAP kinase, and ATM/ATR signaling pathways by Wip1 are important components of its oncogenicity when it is amplified and overexpressed in human cancers