118488595
Gauss–Bonnet coupling constant as a free thermodynamical variable and the associated criticality
The thermodynamic phase space of Gauss–Bonnet (GB) AdS black holes is extended, taking the inverse of the GB coupling constant as a new thermodynamic pressure $$P_{\mathrm {GB}}$$PGB. We studied the critical behavior associated with $$P_{\mathrm {GB}}$$PGB in the extended thermodynamic phase space at fixed cosmological constant and electric charge. The result shows that when the black holes are neutral, the associated critical points can only exist in five dimensional GB-AdS black holes with spherical topology, and the corresponding critical exponents are identical to those for the Van der Waals system. For charged GB-AdS black holes, it is shown that there can be only one critical point in five dimensions (for black holes with either spherical or hyperbolic topologies), which also requires the electric charge to be bounded within some appropriate range; while in $$d>5$$d>5 dimensions, there can be up to two different critical points at the same electric charge, and the phase transition can occur only at temperatures which are not in between the two critical values.
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.
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.
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.
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
1190941
Higher moments of net proton multiplicity distributions at RHIC.
We report the first measurements of the kurtosis (κ), skewness (S), and variance (σ2) of net-proton multiplicity (Np-Np) distributions at midrapidity for Au+Au collisions at square root of s(NN)=19.6, 62.4, and 200 GeV corresponding to baryon chemical potentials (μB) between 200 and 20 MeV. Our measurements of the products κσ2 and Sσ, which can be related to theoretical calculations sensitive to baryon number susceptibilities and long-range correlations, are constant as functions of collision centrality. We compare these products with results from lattice QCD and various models without a critical point and study the square root of s(NN) dependence of κσ2. From the measurements at the three beam energies, we find no evidence for a critical point in the QCD phase diagram for μB below 200 MeV.
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.
118693623
Angular Reconstruction of a Lead Scintillating-Fiber Sandwiched Electromagnetic Calorimeter
The Neighbor Cell Deposited Energy Ratio (NCDER) is a new method that is proposed to reconstruct incidence position in a single layer for a 3-dimensional imaging electromagnetic calorimeter (ECAL). This method was applied to reconstruct the ECAL test beam data for the Alpha Magnetic Spectrometer-02 (AMS-02). The results show that this method can achieve an angular resolution of 7.36 +/- 0.08 degrees/root E circle plus 0.28 +/- 0.02 degrees in the determination of the photon's direction, which is much more precise than that obtained with the commonly-adopted Center of Gravity (COG) method (8.4 +/- 0.1 degrees/root E circle plus 0.8 +/- 0.3 degrees). Furthermore, since it uses only the properties of electromagnetic showers, this new method could also be used for other type of fine grain sampling calorimeters.
122609851
Study of split higher order mode resonances in superconducting cavities
Abstract Split resonances are a common appearance in superconducting cavities and are studied here on a specific example. A five cell superconducting cavity suitable for the envisioned electron-hadron collider eRHIC was designed and will be used in the upcoming “Coherent electron Cooling” Proof-of-Principle experiment. The superconducting cavity is intended for high-current applications, and beam stability depends on minimizing the Higher Order Modes (HOM). This was attempted in the design phase and will be done with appropriate mode dampers in operation. The design was implemented as a copper cavity and two Niobium cavities were fabricated. The availability of the copper model provided a convenient opportunity to confirm the design and to study potentially nefarious HOMs. Selected high- Q resonances were investigated via bead pull measurements. The appearance of split resonances impeded their study and suitable methods of HOM identification are presented in this report.
111375996
DIGITAL LONGITUDINAL BUNCH-BY-BUNCH FEEDBACK SYSTEM FOR THE HLS II
In order to suppress the longitudinal coupled bunch instabilities, a digital longitudinal bunch-by-bunch feedback system will be developed in the upgrade project of Hefei Light Source (HLS II). The longitudinal feedback system consists of a pickup BPM, a front- end/back-end signal processor unit to detect the phase errors of all electron bunches, an iGp signal processor to calculate correction signals of those bunches, two RF power amplifiers, and a longitudinal kicker to supply proper correction energy kicks to individual bunches. A new waveguide overloaded cavity longitudinal feedback kicker has been designed with broadband and high shunt impedance. In this paper, we describe an overview of the new longitudinal feedback system.