scholarly journals Superradiance in a ghost-free scalar theory

2018 ◽  
Vol 98 (8) ◽  
Author(s):  
Valeri P. Frolov ◽  
Andrei Zelnikov
Keyword(s):  
Scalar Theory ◽  
Free Scalar

scholarly journals Weak cosmic censorship with self-interacting scalar and bound on charge to mass ratio

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Yan Song ◽  
Tong-Tong Hu ◽  
Yong-Qiang Wang
Keyword(s):  
Scalar Field ◽  
Scalar Fields ◽  
Cosmic Censorship ◽  
Mass Ratio ◽  
Quartic Coupling ◽  
Scalar Theory ◽  
Free Scalar ◽  
The One ◽  
Nonzero Scalar ◽  
Large Charge

Abstract We study the model of four-dimensional Einstein-Maxwell-Λ theory minimally coupled to a massive charged self-interacting scalar field, parameterized by the quartic and hexic couplings, labelled by λ and β, respectively. In the absence of scalar field, there is a class of counterexamples to cosmic censorship. Moreover, we investigate the full nonlinear solution with nonzero scalar field included, and argue that these counterexamples can be removed by assuming charged self-interacting scalar field with sufficiently large charge not lower than a certain bound. In particular, this bound on charge required to preserve cosmic censorship is no longer precisely the weak gravity bound for the free scalar theory. For the quartic coupling, for λ < 0 the bound is below the one for the free scalar fields, whereas for λ > 0 it is above. Meanwhile, for the hexic coupling the bound is always above the one for the free scalar fields, irrespective of the sign of β.

scholarly journals Dynamics of logarithmic negativity and mutual information in smooth quenches

2020 ◽  
Vol 2020 (7) ◽  
Author(s):  
Hiroyuki Fujita ◽  
Mitsuhiro Nishida ◽  
Masahiro Nozaki ◽  
Yuji Sugimoto
Keyword(s):  
Mutual Information ◽  
Time Evolution ◽  
Qualitative Difference ◽  
Time Dependent ◽  
Late Time ◽  
Finite Mass ◽  
Scalar Theory ◽  
Quasi Particle ◽  
Logarithmic Negativity ◽  
Free Scalar

Abstract We study the time evolution of mutual information (MI) and logarithmic negativity (LN) in two-dimensional free scalar theory with two kinds of time-dependent masses: one time evolves continuously from non-zero mass to zero; the other time evolves continuously from finite mass to finite mass, but becomes massless once during the time evolution. We call the former protocol ECP, and the latter protocol CCP. Through numerical computation, we find that the time evolution of MI and LN in ECP follows a quasi-particle picture except for their late-time evolution, whereas that in CCP oscillates. Moreover, we find a qualitative difference between MI and LN which has not been known so far: MI in ECP depends on the slowly moving modes, but LN does not.

scholarly journals COVARIANT FORMULATION OF NOETHER'S THEOREM FOR κ-MINKOWSKI TRANSLATIONS

2009 ◽  
Vol 24 (07) ◽  
pp. 1333-1358 ◽  
Author(s):  
ALESSANDRA AGOSTINI
Keyword(s):  
Plane Waves ◽  
Equation Of Motion ◽  
Space Time ◽  
Noncommutative Space ◽  
Covariant Formulation ◽  
Scalar Theory ◽  
Noether’S Theorem ◽  
Noether's Theorem ◽  
Free Scalar ◽  
Conserved Currents

The problem of finding a formulation of Noether's theorem in noncommutative geometry is very important in order to obtain conserved currents and charges for particles in noncommutative space–times. In this paper, we formulate Noether's theorem for translations of κ-Minkowski noncommutative space–time on the basis of the five-dimensional κ-Poincaré covariant differential calculus. We focus our analysis on the simple case of free scalar theory. We obtain five conserved Noether currents, which give rise to five energy–momentum charges. By applying our result to plane waves it follows that the energy–momentum charges satisfy a special-relativity dispersion relation with a generalized mass given by the fifth charge. In this paper, we provide also a rigorous derivation of the equation of motion from Hamilton's principle in noncommutative space–time, which is necessary for the Noether analysis.

scholarly journals Radiation from an emitter in the ghost free scalar theory

2016 ◽  
Vol 93 (10) ◽  
Author(s):  
Valeri P. Frolov ◽  
Andrei Zelnikov
Keyword(s):  
Scalar Theory ◽  
Free Scalar

scholarly journals Free energy and defect C-theorem in free scalar theory

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Tatsuma Nishioka ◽  
Yoshiki Sato
Keyword(s):  
Boundary Conditions ◽  
Dirichlet Boundary ◽  
Neumann Boundary ◽  
Flat Space ◽  
Neumann Boundary Conditions ◽  
Dirichlet Boundary Conditions ◽  
Scalar Theory ◽  
Free Scalar ◽  
The Difference ◽  
Recent Classification

Abstract We describe conformal defects of p dimensions in a free scalar theory on a d-dimensional flat space as boundary conditions on the conformally flat space ℍp+1× 𝕊d−p−1. We classify two types of boundary conditions, Dirichlet type and Neumann type, on the boundary of the subspace ℍp+1 which correspond to the types of conformal defects in the free scalar theory. We find Dirichlet boundary conditions always exist while Neumann boundary conditions are allowed only for defects of lower codimensions. Our results match with a recent classification of the non-monodromy defects, showing Neumann boundary conditions are associated with non-trivial defects. We check this observation by calculating the difference of the free energies on ℍp+1× 𝕊d−p−1 between Dirichlet and Neumann boundary conditions. We also examine the defect RG flows from Neumann to Dirichlet boundary conditions and provide more support for a conjectured C-theorem in defect CFTs.

scholarly journals Critical behavior of the 2d scalar theory: resumming the N8LO perturbative mass gap

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Gustavo O. Heymans ◽  
Marcus Benghi Pinto
Keyword(s):  
Perturbation Theory ◽  
Critical Behavior ◽  
State Of The Art ◽  
Critical Coupling ◽  
Scalar Theory ◽  
Perturbative Series ◽  
Supercritical Region ◽  
Mass Gap ◽  
Perturbative Result ◽  
Symmetric Phase

Abstract We apply the optimized perturbation theory (OPT) to resum the perturbative series describing the mass gap of the bidimensional ϕ4 theory in the ℤ2 symmetric phase. Already at NLO (one loop) the method is capable of generating a quite reasonable non-perturbative result for the critical coupling. At order-g7 we obtain gc = 2.779(25) which compares very well with the state of the art N8LO result, gc = 2.807(34). As a novelty we investigate the supercritical region showing that it contains some useful complimentary information that can be used in extrapolations to arbitrarily high orders.

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