119260243
Holographic superconductors in the AdS black-hole spacetime with a global monopole
Abstract We study holographic superconductors in the Schwarzschild–AdS black hole with a global monopole through a charged complex scalar field. We calculate the condensates of the charged operators in the dual conformal field theories (CFTs) and discuss the effects of the global monopole on the condensation formation. Moreover, we compute the electric conductive using the probe approximation and find that the properties of the conductive are quite similar to those in the Schwarzschild–AdS black hole. These results can help us know more about holographic superconductors in the asymptotic AdS black holes.
121869215
Dirac quasinormal modes of the Garfinkle-Horowitz-Strominger dilaton black-hole spacetime
Adopting the P?schl?Teller potential approximation, the quasinormal frequencies of the massless Dirac fields are evaluated in the Garfinkle?Horowitz?Strominger dilaton black-hole spacetime. We find that the real parts of the quasinormal frequencies increase as the orbital angular momentum k or a increases, where a is a parameter related to the dilaton field. The magnitude of imaginary parts decreases with k for the fixed a and overtone number n, while for fixed k and n, it is not a monotonic function of a and has a maximum at a point near a = 1.4?1.6, where the waves decay most rapidly. Another interesting feature is that the imaginary parts tend to zero and the real parts to k/2 as a approaches 2. We also find that the variation of the imaginary parts with the real parts in the Garfinkle?Horowitz?Strominger dilaton hole spacetimes is nonlinear, which becomes more complex than that in the Reissner?Nordstr?m black-hole spacetime.
118654249
Particle acceleration on the background of the Kerr―Taub―NUT spacetime
Abstract We study the collision of two particles with the different rest masses moving in the equatorial plane of a Kerr–Taub–NUT spacetime and get the center-of-mass (CM) energy for the particles. We find that the CM energy depends not only on the rotation parameter, a , but also on the NUT charge of the Kerr–Taub–NUT spacetime, n . Especially, for the extremal Kerr–Taub–NUT spacetime, an unlimited CM energy can be approached if the parameter a is in the range [ 1 , 2 ] , which is different from that of the Kerr and Kerr–Newman black holes.
119127372
Rotating charged black hole with Weyl corrections
We present firstly a four-dimensional spherical symmetric black hole with small Weyl corrections and find that with increasing Weyl corrections the region of the event horizon existence for the black hole in the parameter space increases for the negative Weyl coupling parameter and decreases for the positive one. Moreover, we also obtain a rotating charged black hole with weak Weyl corrections by the method of complex coordinate transformation. Our results show that the sign of Weyl coupling parameter $\alpha$ yields the different spatial topology of the event horizons for the black hole with its parameters lied in some special regions in the parameter space. We also analyze the dependence of the ergosphere on the Weyl coupling parameter $\alpha$ and find that with the increase of the Weyl corrections the ergosphere in the equatorial plane becomes thick for a black hole with $\alpha>0$, but becomes thin in the case with $\alpha<0$, which means that the energy extraction become easier in the background of a black hole with the positive Weyl coupling parameter, but more difficult in the background of a black hole with the negative one.
119285485
$P-V$ criticality of AdS black hole in $f(R)$ gravity
We study thermodynamics of a charged AdS black hole in the special $f(R)$ correction with the constant Ricci scalar curvature. Our results show that the the $f(R)$ correction influences the Gibbs free energy and the phase transition of system. The ratio $\rho_c$ occurred at the critical point increases monotonically with the derivative term $f'(R_0)$. We also disclose that the critical exponents are the same as those of the liquid-gas phase transition in the Van der Waals model, which does not depend on the $f(R)$ correction considered here.
118567951
Phantom scalar emission in the Kerr black hole spacetime
We study the absorption probability and Hawking radiation spectra of a phantom scalar field in the Kerr black hole spacetime. We find that the presence of negative kinetic energy terms modifies the standard results in the graybody factor, super-radiance and Hawking radiation. Comparing with the usual scalar particle, the phantom scalar emission is enhanced in the black hole spacetime.
119321899
Geodesically complete analytic solutions for a cyclic universe
We present analytic solutions to a class of cosmological models described by a canonical scalar field minimally coupled to gravity and experiencing self interactions through a hyperbolic potential. Using models and methods inspired by 2T-physics, we show how analytic solutions can be obtained in flat/open/closed Friedmann-Robertson-Walker universes. Among the analytic solutions, there are many interesting geodesically complete cyclic solutions in which the universe bounces at either zero or finite sizes. When geodesic completeness is imposed, it restricts models and their parameters to a certain parameter subspace, including some quantization conditions on initial conditions in the case of zero-size bounces, but no conditions on initial conditions for the case of finite-size bounces. We will explain the theoretical origin of our model from the point of view of 2T-gravity as well as from the point of view of the colliding branes scenario in the context of M-theory. We will indicate how to associate solutions of the quantum Wheeler-deWitt equation with our classical analytic solutions, mention some physical aspects of the cyclic solutions, and outline future directions.
118376307
Search for GeV Gamma‐Ray Bursts with the ARGO‐YBJ Detector in Scaler Mode
The ARGO‐YBJ experiment is a full coverage array made of Resistive Plate Chambers (RPCs) operated in streamer mode to detect the extensive array showers (EASs). With large field of view (>2sr) and high duty cycle (>90%), the ARGO‐YBJ detector is the right ground‐based apparatus to detect VHE GRBs, while the high altitude (4300 m a.s.l) and scaler working mode enable it to detect GRBs in the GeV region as high energy follow‐up observation of satellites such as SWIFT. If a GRB signal is detected, the four scaler channels, which correspond to different energy thresholds, can provide further information on the energy spectrum and its cut‐off. More than 40 SWIFT GRBs were in ARGO‐YBJ field of view, no significant excess was detected till now.
124511058
THE COUPLED RESONATOR MODEL AND THE DISTRIBUTION OF THE ELECTRIC FIELD ON THE AXIS IN THE PERIODIC CAVITY CHAIN. (IN CHINESE)
The Coupled resonator model and the distribution of the electric Field on the axisin the singly periodic cavity chain and biperiodic chain with full-cavity terminationsare analysed by Helmholtz Equation using the symmetry properties of the structure.It is another method to check coupled circuit theory. The results given in this paper forthe singly periodic cavity chain with full- cavity terminations was verified by a 600MHZ linac model of IHEP.
118403311
Geometry and optics calibration of WFCTA prototype telescopes using star light
The Large High Altitude Air Shower Observatory project is proposed to study high energy gamma ray astronomy ( 40 GeV-1 PeV ) and cosmic ray physics ( 20 TeV-1 EeV ). The wide field of view Cherenkov telescope array, as a component of the LHAASO project, will be used to study energy spectrum and compositions of cosmic ray by measuring the total Cherenkov light generated by air showers and shower maximum depth. Two prototype telescopes have been in operation since 2008. The pointing accuracy of each telescope is crucial to the direction reconstruction of the primary particles. On the other hand the primary energy reconstruction relies on the shape of the Cherenkov image on the camera and the unrecorded photons due to the imperfect connections between photomultiplier tubes. UV bright stars are used as point-like objects to calibrate the pointing and to study the optical properties of the camera, the spot size and the fractions of unrecorded photons in the insensitive areas of the camera.
119638771
Dual Field Theories In (d-1)+1 Emergent Spacetimes From A Unifying Field Theory In d+2 Spacetime
According to two-time physics, there is more to space and time than can be garnered with the ordinary formulation of physics. Two-time physics has shown that the standard model of particles and forces is successfully reproduced by a two-time field theory in four space and two time dimensions projected as a holographic image on an emergent space-time in 3 + 1 dimensions. Among the successes of this approach is the resolution of the strong CP problem of QCD as an outcome of the restrictions imposed by the higher symmetry structures in 4 + 2 dimensions. In this paper we launch a program to construct the duals of the standard model as other holographic images of the same 4 + 2 dimensional theory on a variety of emergent spacetimes in 3 + 1 dimensions. These dual field theories are obtained as a family of gauge choices in the master 4 + 2 field theory. In the present paper we deal with some of the simpler gauge choices which lead to interacting Klein-Gordon field theories for the conformal scalar with a predicted SO(d,2) symmetry in a variety of interesting curved spacetimes in (d - 1) + 1 dimensions. More challenging and more interesting gauge choices (including some that relate to mass) which are left to future work are also outlined. Through this approach we discover a new realm of previously unexplored dualities and hidden symmetries that exist both in the macroscopic and microscopic worlds, at the classical and quantum levels. Such phenomena predicted by Two time physics (2T-physics) can in principle be confirmed both by theory and experiment. One time physics (IT-physics) can be used to analyze the predictions but in most instances gives no clue that the predicted phenomena exist in the first place. This point of view suggests a new paradigm for the construction of a fundamental theory that is likely to impact on the quest for unification.