119257757
Accelerating BTZ spacetime
An exact solution of (2 + 1)-dimensional Einstein gravity with a cosmological constant is studied. The corresponding spacetime is interpreted as an accelerating BTZ spacetime. The proper acceleration, horizon structure, temperature and entropy are presented in detail. The metric being studied is very similar to the one studied by Astorino (2011 J. High Energy Phys. JHEP01(2011)114) but the range of parameters is different which results in significant changes in the causal structures.
119245563
FIVE-DIMENSIONAL VACUUM EINSTEIN SPACETIMES IN C-METRIC LIKE COORDINATES
A five-dimensional Einstein spacetime with (non)vanishing cosmological constant is analyzed in detail. The metric is in close analogy with the four-dimensional massless uncharged C-metric in many aspects. The coordinate system, horizons and causal structures, relations to standard form of de Sitter, anti de Sitter and Minkowski vacua are investigated. After a boost and Kaluza–Klein reduction, we get an exact solution of four-dimensional Einstein–Maxwell–Liouville theory which reduces to a solution to Einstein–Liouville theory in the limit of zero boost velocity and to that of Einstein–Maxwell–dilaton theory in the case of zero cosmological constant.
118511063
Exact black hole formation in three dimensions
Abstract We consider three dimensional Einstein gravity non-minimally coupled to a real scalar field with a self-interacting scalar potential and present the exact black hole formation in three dimensions. Firstly we obtain an exact time-dependent spherically symmetric solution describing the gravitational collapse to a scalar black hole at the infinite time, i.e. in the static limit. The solution can only be asymptotically AdS because of the No–Go theorem in three dimensions which is resulting from the existence of a smooth black hole horizon. Then we analyze their geometric properties and properties of the time evolution. We also get the exact time-dependent solution in the minimal coupling model after taking a conformal transformation.
122503839
Properties of an Accelerating Gauss-Bonnet Vacuum in Five Dimensions
The causal structure of a five-dimensional C-metric like vacuum solution of Gauss-Bonnet gravity is analyzed in detail, the Gauss-Bonnet parameter make it more complex than that of a C-metric like solution of Einstein gravity. The acceleration of the observer fixed at a spatial position is calculated, the effect of the Gauss-Bonnet parameter comes in, but the acceleration of the origin is not affected by the parameter. The geodesics of the test particles in the spacetime are investigated, it is found that objects accelerate to go to the horizon in the accelerating spacetime.
55487930
Thermodynamics of rotating black holes with scalar hair in three dimensions
Introducing a new form of scalar potential $V(\ensuremath{\phi})$, we derive a proper form of the rotating black hole solution in three-dimensional Einstein gravity with nonminimally coupled scalar field and find that the first law of thermodynamics of this new rotating hairy black hole can be protected, where the scalar field parameter $B$ is constrained to relate to the black hole size. We also disclose the Hawking\char21{}Page phase transition between this rotating hairy black holes and the pure thermal radiation. Moreover, we study phase transitions between this rotating hairy black hole and rotating Banados-Teitelboim-Zanelli (BTZ) black hole. Considering the matchings for the temperature and angular momentum, we find that the rotating BTZ black hole always has smaller free energy, which is a thermodynamically more preferred phase. Additionally, we evaluate the thermodynamics of the rotating black hole with minimally coupled scalar hair in three dimensions, which exhibits that the thermodynamical behaviors of this rotating hairy black hole are very similar to those of the rotating black hole with nonminimally coupled scalar hair.
119069530
Landau meets Newton: time translation symmetry breaking in classical mechanics
AbstractEvery classical Newtonian mechanical system can be equipped with anonstandard Hamiltonian structure, in which the Hamiltonian is the squareof the canonical Hamiltonian up to a constant shift, and the Poisson bracketis nonlinear. In such a formalism, time translation symmetry can be spon-taneously broken, provided the potential function becomes negative. A niceanalogy between time translation symmetry breaking and the Landau the-ory of second order phase transitions is established, together with severalexample cases illustrating time translation breaking ground states. In par-ticular, the CDM model of FRW cosmology is reformulated as the timetranslation symmetry breaking ground states.Keywords: time translation symmetry breaking, Hamiltonian formalism,Landau theory of phase transition, CDM modelPACS: 1 Introduction Spontaneous symmetry breaking plays an essential role in many areas in moderntheoretical physics such as the gauge theory of particle physics and the Landau-Ginzberg theory of phase transitions in condensed matter physics. Spontaneouslybroken symmetries can either be internal symmetry (such as gauge and chiralsymmetries) or spacial symmetry (such as space translation and rotation symme-tries). Shapere and Wilczek recently discovered [1] that even the time translationsymmetry can be spontaneously broken in some singular Lagrangian systems. Ina previous work [2], we showed that the spontaneous breaking of time transla-tion symmetry can also be described in Hamiltonian formalism using some non-1
124318854
Precision measurement of positron fraction by AMS-02
118561275
Test of the prototype of electron detector for LHAASO project using cosmic rays
LHAASO project is to be built in south-west China, which use an array of 5137 election detectors for the measurement of the incident electrons arriving at the detector plane. For the quality control of the big quantity of electron detectors, a cosmic ray hodoscope with two-dimensional spacial sensitivity and good time resolution has been developed. The ?rst prototype of electron detector is tested with the hodoscope and the performance of the detector is validated to be consistent with the design.
6716887
Three-particle coincidence of the long range pseudorapidity correlation in high energy nucleus-nucleus collisions.
We report the first three-particle coincidence measurement in pseudorapidity (Δη) between a high transverse momentum (p⊥) trigger particle and two lower p⊥ associated particles within azimuth |Δϕ|<0.7 in square root of s(NN)=200 GeV d+Au and Au+Au collisions. Charge ordering properties are exploited to separate the jetlike component and the ridge (long range Δη correlation). The results indicate that the correlation of ridge particles are uniform not only with respect to the trigger particle but also between themselves event by event in our measured Δη. In addition, the production of the ridge appears to be uncorrelated to the presence of the narrow jetlike component.
55660748
HOM identification by bead pulling in the Brookhaven ERL cavity
Abstract Exploratory measurements of the Brookhaven Energy Recovery Linac (ERL) cavity at superconducting temperature produced a long list of high order modes (HOMs). The niobium 5-cell cavity is terminated at each end with HOM ferrite dampers that successfully reduce the Q -factors to levels required to avoid beam break up (BBU) instabilities. However, a number of un-damped resonances with Q ≥10 6 were found at 4 K and their mode identification forms the focus of this paper. The approach taken here consists of bead pulling on a copper (Cu) replica of the ERL cavity with dampers involving various network analyzer measurements. Several different S 21 transmission measurements are used, including those taken from the fundamental input coupler to the pick-up probe across the cavity, others between beam-position monitor probes in the beam tubes, and also between probes placed into the cells. The bead pull technique suitable for HOM identification with a metallic needle or dielectric bead is detailed. This paper presents the results for HOMs in the first two dipole bands, the un-damped modes in the first quadrupole band, and the identification of several high- Q modes beyond.
6908824
NGN, QCD 2 and chiral phase transition from string theory
We construct a D2-D8-8 configuration in string theory, it can be described at low energy by two dimensional field theory. In the weak coupling region, the low energy theory is a nonlocal generalization of Gross-Neveu(GN) model which dynamically breaks the chiral flavor symmetry U(Nf)L × U(Nf)R at large Nc and finite Nf. However, in the strong coupling region, we can use the SUGRA/Born-Infeld approximation to describe the low energy dynamics of the system. Also, we analyze the low energy dynamics about the configuration of wrapping the one direction of D2 brane on a circle with anti-periodic boundary condition of fermions. The fermions and scalars on D2 branes get mass and decouple from the low energy theory. The IR dynamics is described by the QCD2 at weak coupling. In the opposite region, the dynamics has a holographic dual description. And we have discussed the phase transition of chiral symmetry breaking at finite temperature. Finally, after performing T-duality, this configuration is related to some other brane configurations.