11,327 research outputs found
Charge Influence On Mini Black Hole's Cross Section
In this work we study the electric charge effect on the cross section
production of charged mini black holes (MBH) in accelerators. We analyze the
charged MBH solution using the {\it fat brane} approximation in the context of
the ADD model. The maximum charge-mass ratio condition for the existence of a
horizon radius is discussed. We show that the electric charge causes a decrease
in this radius and, consequently, in the cross section. This reduction is
negligible for protons and light ions but can be important for heavy ions.Comment: 4 pages, 0 figure. To be published in Int. J. Mod. Phys. D
Warp-X: a new exascale computing platform for beam-plasma simulations
Turning the current experimental plasma accelerator state-of-the-art from a
promising technology into mainstream scientific tools depends critically on
high-performance, high-fidelity modeling of complex processes that develop over
a wide range of space and time scales. As part of the U.S. Department of
Energy's Exascale Computing Project, a team from Lawrence Berkeley National
Laboratory, in collaboration with teams from SLAC National Accelerator
Laboratory and Lawrence Livermore National Laboratory, is developing a new
plasma accelerator simulation tool that will harness the power of future
exascale supercomputers for high-performance modeling of plasma accelerators.
We present the various components of the codes such as the new Particle-In-Cell
Scalable Application Resource (PICSAR) and the redesigned adaptive mesh
refinement library AMReX, which are combined with redesigned elements of the
Warp code, in the new WarpX software. The code structure, status, early
examples of applications and plans are discussed
Membrane amplitude and triaxial stress in twisted bilayer graphene deciphered using first-principles directed elasticity theory and scanning tunneling microscopy
Twisted graphene layers produce a moir\'e pattern (MP) structure with a
predetermined wavelength for given twist angle. However, predicting the
membrane corrugation amplitude for any angle other than pure AB-stacked or
AA-stacked graphene is impossible using first-principles density functional
theory (DFT) due to the large supercell. Here, within elasticity theory we
define the MP structure as the minimum energy configuration, thereby leaving
the height amplitude as the only unknown parameter. The latter is determined
from DFT calculations for AB and AA stacked bilayer graphene in order to
eliminate all fitting parameters. Excellent agreement with scanning tunneling
microscopy (STM) results across multiple substrates is reported as function of
twist angle.Comment: to appear in Phys. Rev.
Near-extremal and extremal quantum-corrected two-dimensional charged black holes
We consider charged black holes within dilaton gravity with
exponential-linear dependence of action coefficients on dilaton and minimal
coupling to quantum scalar fields. This includes, in particular, CGHS and RST
black holes in the uncharged limit. For non-extremal configuration quantum
correction to the total mass, Hawking temperature, electric potential and
metric are found explicitly and shown to obey the first generalized law. We
also demonstrate that quantum-corrected extremal black holes in these theories
do exist and correspond to the classically forbidden region of parameters in
the sense that the total mass ( is a charge). We show that in
the limit (where is the Hawking temperature) the mass and
geometry of non-extremal configuration go smoothly to those of the extremal
one, except from the narrow near-horizon region. In the vicinity of the horizon
the quantum-corrected geometry (however small quantum the coupling parameter
would be) of a non-extremal configuration tends to not the
quantum-corrected extremal one but to the special branch of solutions with the
constant dilaton (2D analog of the Bertotti-Robinson metric) instead.
Meanwhile, if exactly, the near-extremal configuration tends to the
extremal one. We also consider the dilaton theory which corresponds classically
to the spherically-symmetrical reduction from 4D case and show that for the
quantum-corrected extremal black hole .Comment: 25 pages. Typos corrected. To appear in Class. Quant. Gra
Flavor-symmetry Breaking with Charged Probes
We discuss the recombination of brane/anti-brane pairs carrying brane
charge in . These configurations are dual to co-dimension one
defects in the super-Yang-Mills description. Due to their
charge, these defects are actually domain walls in the dual gauge theory,
interpolating between vacua of different gauge symmetry. A pair of unjoined
defects each carry localized dimensional fermions and possess a global
flavor symmetry while the recombined brane/anti-brane pairs
exhibit only a diagonal U(N). We study the thermodynamics of this
flavor-symmetry breaking under the influence of external magnetic field.Comment: 21 pages, 10 figure
Flavor from M5-branes
We study various aspects of the defect conformal field theory that arises
when placing a single M5-brane probe in AdS_4 x S^7. We derive the full set of
fluctuation modes and dimensions of the corresponding dual operators. We argue
that the latter does not depend on the presence of a non-trivial magnetic flux
on the M5-brane world-volume. Finally we give a mass to the hypermultiplet
living on the defect, and compute the resulting mesonic spectrum.Comment: 19 page
Black Hole Relics in String Gravity: Last Stages of Hawking Evaporation
One of the most intriguing problem of modern physics is the question of the
endpoint of black hole evaporation. Based on Einstein-dilaton-Gauss-Bonnet four
dimensional string gravity model we show that black holes do not disappear and
that the end of the evaporation process leaves some relic. The possibility of
experimental detection of the remnant black holes is investigated. If they
really exist, such objects could be a considerable part of the non baryonic
dark matter in our Universe.Comment: 15 pages, accepted to Class. Quant. Gra
Uniqueness Theorem of Static Degenerate and Non-degenerate Charged Black Holes in Higher Dimensions
We prove the uniqueness theorem for static higher dimensional charged black
holes spacetime containing an asymptotically flat spacelike hypersurface with
compact interior and with both degenerate and non-degenerate components of the
event horizon.Comment: 9 pages, RevTex, to be published in Phys.Rev.D1
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