14727533
Transverse Kähler geometry of Sasaki manifolds and toric Sasaki-Einstein manifolds
In this paper we study compact Sasaki manifolds in view of transverse K\"ahler geometry and extend some results in K\"ahler geometry to Sasaki manifolds. In particular we define integral invariants which obstruct the existence of transverse K\"ahler metric with harmonic Chern forms. The integral invariant $f_1$ for the first Chern class case becomes an obstruction to the existence of transverse K\"ahler metric of constant scalar curvature. We prove the existence of transverse K\"ahler-Ricci solitons (or {\it Sasaki-Ricci soliton}) on compact toric Sasaki manifolds whose basic first Chern form of the normal bundle of the Reeb foliation is positive, and in particular the existence of Sasaki-Einstein metrics for compact toric Sasaki manifolds with vanishing $f_1$. We will further show that if $S$ is a compact toric Sasaki manifold such that the basic first Chern class is positive then by deforming the Reeb field we get a Sasaki-Einstein structure on $S$. As an application we obtain irregular toric Sasaki-Einstein metrics on the unit circle bundles of the powers of the anti-canonical bundle of the two-point blow-up of the complex projective plane.
119302009
The Gauss-Bonnet-Chern mass of conformally flat manifolds
In this paper we show positive mass theorems and Penrose type inequalities for the Gauss-Bonnet-Chern mass, which was introduced recently in \cite{GWW}, for asymptotically flat CF manifolds and its rigidity.
119275897
A new mass for asymptotically flat manifolds
Abstract In this paper we introduce a mass for asymptotically flat manifolds by using the Gauss–Bonnet curvature. We first prove that the mass is well-defined and is a geometric invariant, if the Gauss–Bonnet curvature is integrable and the decay order τ satisfies τ > n − 4 3 . Motivated by an elegant idea of Lam [35] , we then show a positive mass theorem for this new mass for asymptotically flat graphs over R n . Moreover we obtain various Penrose type inequalities in this case. In these Penrose type inequalities we establish relationship between the new mass and various geometric integrals.
118617483
A positive mass theorem in the Einstein-Gauss-Bonnet theory
As an interesting application of the Einstein-Gauss-Bonnet theory and our work on the Gauss-Bonnet-Chern mass (Ge, Wang, Wu), we obtain a positive mass theorem for asymptotically flat graphs in $\R^{n+1}$ under a condition that $R+\alpha L_2$ is non-negative, where $R$ is the scalar curvature, $\alpha\in\R$ a constant and $L_2$ the second Gauss-Bonnet curvature. A Penrose type inequality is also obtained in the case $\alpha>0$.
118032595
Progress on Analytical Modeling of Coherent Electron Cooling
We report recent progresses on analytical studies of Coherent Electron Cooling. The phase space electron beam distribution obtained from the 1D FEL amplifier is applied to an infinite electron plasma model and the electron density evolution inside the kicker is derived. We also investigate the velocity modulation in the modulator and obtain a closed form solution for the current density evolution for infinite homogeneous electron plasma.
122537214
Search for local parity violation with STAR ZDC-SMD
Parity-odd domains are predicted to lead to charge separation of quarks along the orbital momentum of the system created in non-central relativistic heavy ion collisions. A signal consistent with several of the theoretical expectations has been detected by STAR, with a three particle azimuthal correlator which is a -even observable, but still sensitive to the charge separation effect. In this correlator, the first two particles are used to reveal the physics of interest, and the third particle serves as a reference for the reaction plane. In this work, to minimize the non-parity correlation between the third particle and the first two, we utilize the spectator neutrons detected by STAR ZDC-SMDs to define the event plane. The 1st-order event plane thus obtained can also be used to study the global strong parity violation effect, and to provide further systematic checks for this analysis. We report measurements of both -even and -odd observables using the STAR ZDC-SMDs in Au+Au at 200 GeV. The results are presented as a function of collision centrality, particle separation in rapidity and transverse momentum (pT). Systematic checks on the impact from the directed flow will also be discussed.
118611881
A study on the relations between the topological parameter and entanglement
Abstract In this Letter, some relations between the topological parameter d and concurrences of the projective entangled states have been presented. It is shown that for the case with d = n , all the projective entangled states of two n -dimensional quantum systems are the maximally entangled states (i.e. C = 1 ). And for another case with d ≠ n , C both approach 0 when d → + ∞ for n = 2 and 3. Then we study the thermal entanglement and the entanglement sudden death (ESD) for a kind of Yang–Baxter Hamiltonian. It is found that the parameter d influences not only the critical temperature T c but also the maximum entanglement value that the system can arrive at. And we also find that the parameter d has a great influence on the ESD.
54868722
EXPERIMENTAL PROGRESS OF DC-SC PHOTOINJECTOR AT PEKING UNIVERSITY*
Beam loading experiments on DC-SC photoinjector test facility have been finished at 4.4 K. Upon the present experiments, the gradient of 6 MV/m is achieved. The maximum energy gain is 1.1 MeV at 4.4 K. With average beam current of 270 mA, the measured rms emittance is about 5 mm-mrad at the beam energy of 500 keV. Experiments on the test facility has validated that the DC-SC photoinjector is a good choice to provide moderate average current electron beams with low bunch charge and very high repetition rate.
118705215
The Cryogenic Dark Matter Search and Background Rejection with Event Position Information