The LAMOST Survey of Background Quasars in the Vicinity of the Andromeda and Triangulum Galaxies -- II. Results from the Commissioning Observations and the Pilot Surveys

We present new quasars discovered in the vicinity of the Andromeda and Triangulum galaxies with the LAMOST during the 2010 and 2011 observational seasons. Quasar candidates are selected based on the available SDSS, KPNO 4 m telescope, XSTPS optical, and WISE near infrared photometric data. We present 509 new quasars discovered in a stripe of ~135 sq. deg from M31 to M33 along the Giant Stellar Stream in the 2011 pilot survey datasets, and also 17 new quasars discovered in an area of ~100 sq. deg that covers the central region and the southeastern halo of M31 in the 2010 commissioning datasets. These 526 new quasars have i magnitudes ranging from 15.5 to 20.0, redshifts from 0.1 to 3.2. They represent a significant increase of the number of identified quasars in the vicinity of M31 and M33. There are now 26, 62 and 139 known quasars in this region of the sky with i magnitudes brighter than 17.0, 17.5 and 18.0 respectively, of which 5, 20 and 75 are newly-discovered. These bright quasars provide an invaluable collection with which to probe the kinematics and chemistry of the ISM/IGM in the Local Group of galaxies. A total of 93 quasars are now known with locations within 2.5 deg of M31, of which 73 are newly discovered. Tens of quasars are now known to be located behind the Giant Stellar Stream, and hundreds behind the extended halo and its associated substructures of M31. The much enlarged sample of known quasars in the vicinity of M31 and M33 can potentially be utilized to construct a perfect astrometric reference frame to measure the minute PMs of M31 and M33, along with the PMs of substructures associated with the Local Group of galaxies. Those PMs are some of the most fundamental properties of the Local Group.Comment: 26 pages, 6 figures, AJ accepte

Genomic and oncogenic preference of HBV integration in hepatocellular carcinoma

Hepatitis B virus (HBV) can integrate into the human genome, contributing to genomic instability and hepatocarcinogenesis. Here by conducting high-throughput viral integration detection and RNA sequencing, we identify 4,225 HBV integration events in tumour and adjacent non-tumour samples from 426 patients with HCC. We show that HBV is prone to integrate into rare fragile sites and functional genomic regions including CpG islands. We observe a distinct pattern in the preferential sites of HBV integration between tumour and non-tumour tissues. HBV insertional sites are significantly enriched in the proximity of telomeres in tumours. Recurrent HBV target genes are identified with few that overlap. The overall HBV integration frequency is much higher in tumour genomes of males than in females, with a significant enrichment of integration into chromosome 17. Furthermore, a cirrhosis-dependent HBV integration pattern is observed, affecting distinct targeted genes. Our data suggest that HBV integration has a high potential to drive oncogenic transformation

Search for the decay J/ψ→γ+invisibleJ/\psi\to\gamma + \rm {invisible}

We search for $J/\psi$ radiative decays into a weakly interacting neutral particle, namely an invisible particle, using the $J/\psi$ produced through the process $\psi(3686)\to\pi^+\pi^-J/\psi$ in a data sample of $(448.1\pm2.9)\times 10^6$ $\psi(3686)$ decays collected by the BESIII detector at BEPCII. No significant signal is observed. Using a modified frequentist method, upper limits on the branching fractions are set under different assumptions of invisible particle masses up to 1.2 $\mathrm{\ Ge\kern -0.1em V}/c^2$. The upper limit corresponding to an invisible particle with zero mass is 7.0$\times 10^{-7}$ at the 90\% confidence level

Amplitude analysis of Ds+→π+π−π+D_s^{+} \rightarrow \pi^{+} \pi^{-} \pi^{+}

Utilizing the data set corresponding to an integrated luminosity of $3.19$ fb$^{-1}$ collected by the BESIII detector at a center-of-mass energy of 4.178 GeV, we perform an amplitude analysis of the $D_s^+\to\pi^+\pi^-\pi^+$ decay. The sample contains 13,797 candidates with a signal purity of $\sim$80%. The amplitude and phase of the contributing $\pi\pi$ ${\cal S}$ wave are measured based on a quasi-model-independent approach, along with the amplitudes and phases of the ${\cal P}$ and ${\cal D}$ waves parametrized by Breit-Wigner models. The fit fractions of different intermediate decay channels are also reported.Comment: 14 pages, 6 figure

Determination of the absolute branching fractions of D0→K−e+νe and D+→K¯0e+νe

Using 2.93 fb-1 of e+e- collision data collected with the BESIII detector at a center-of-mass energy of 3.773 GeV, we measure the absolute branching fractions of the decays D0→K-e+νe and D+→K̄0e+νe to be (3.567±0.031stat±0.025syst)% and (8.68±0.14stat±0.16syst)%, respectively. Starting with the process e+e-→DD¯, a new reconstruction method is employed to select events that contain candidates for both D→K̄e+νe and D¯→Ke-ν¯e decays. The branching fractions reported in this work are consistent within uncertainties with previous BESIII measurements that selected events containing D→K̄e+νe and hadronic D¯ decays. Combining our results with the lifetimes of the D0 and D+ mesons and the previous BESIII measurements leads to a ratio of the two decay partial widths of Γ¯D0→K-e+νeΓ¯D+→K̄0e+νe=1.039±0.021. This ratio supports isospin symmetry in the D0→K-e+νe and D+→K̄0e+νe decays within 1.9σ

Search for the lepton number violating decay Σ−→pe−e− and the rare inclusive decay Σ−→Σ+X

Using a data sample of (1310.6±7.0)×106 J/ψ events taken with the BESIII detector at the center-of-mass energy of 3.097 GeV, we search for the first time for the lepton number violating decay ς-→pe-e- and the rare inclusive decay ς-→ς+X, where X denotes any possible particle combination. The ς- candidates are tagged in J/ψ→ς¯(1385)+ς- decays. No signal candidates are found, and the upper limits on the branching fractions at the 90% confidence level are determined to be B(ς-→pe-e-)<6.7×10-5 and B(ς-→ς+X)<1.2×10-4

Measurement of the doubly Cabibbo-suppressed decay D+→K+π+π−π0 with semileptonic tags

We propose a new semileptonic tag method to study the doubly Cabibbo-suppressed D decay in ψ(3770)→DD¯ reaction. Utilizing the dataset corresponding to an integrated luminosity of 2.93 fb-1 at a center-of-mass energy of 3.773 GeV collected by the BESIII detector, we determine the branching fraction for D+→K+π+π-π0 to be (1.03±0.12stat±0.06syst)×10-3, in which the contributions from narrow intermediate resonances, D+→K+η, D+→K+ω, and D+→K+φ have been excluded. Combining the world average of the branching fraction of D+→K-π+π+π0, we determine B(D+→K+π+π-π0)/B(D+→K-π+π+π0)=(1.65±0.21)%, corresponding to (5.73±0.73)tan4θc, where θc is the Cabibbo mixing angle. These results are consistent with our previous measurement with hadronic tags but are significantly larger than other doubly Cabibbo-suppressed decays in the charm sector

Measurements of Born cross sections of e+e−→Ds*+DsJ−+c.c.

The Born cross sections are measured for the first time for the processes e+e-→Ds∗+Ds0∗(2317)-+c.c. and e+e-→Ds∗+Ds1(2460)-+c.c. at the center-of-mass energy s=4.600 GeV, 4.612 GeV, 4.626 GeV, 4.640 GeV, 4.660 GeV, 4.68 GeV, and 4.700 GeV, and for e+e-→Ds∗+Ds1(2536)-+c.c. at s=4.660 GeV, 4.680 GeV, and 4.700 GeV, using data samples collected with the BESIII detector at the BEPCII collider. No structures are observed in cross-section distributions for any of the processes