9,415 research outputs found
Thermal Radiation from a Fluctuating Event Horizon
We consider a pointlike two-level system undergoing uniformly accelerated
motion. We evaluate the transition probability for a finite time interval of
this system coupled to a massless scalar field near a fluctuating event
horizon. Horizon fluctuations are modeled using a random noise which generates
light-cone fluctuations. We study the case of centered, stationary and Gaussian
random processes. The transition probability of the system is obtained from the
positive-frequency Wightman function calculated to one loop order in the noise
averaging process. Our results show that the fluctuating horizon modifies the
thermal radiation but leaves unchanged the temperature associated with the
acceleration.Comment: 8 pages, 3 figure
Correlations and realistic interactions in doubly closed shell nuclei
We review the latest variational calculations of the ground state properties
of doubly closed shell nuclei, from C to Pb, with semirealistic
and realistic two- and three-nucleon interactions. The studies are carried on
within the framework of the correlated basis function theory and integral
equations technique, with state dependent correlations having central and
tensor components. We report results for the ground state energy, one- and
two-body densities and static structure functions. For O and Ca
we use modern interactions and find that the accuracy of the method is
comparable to that attained in nuclear matter with similar hamiltonians, giving
nuclei underbound by 2 MeV/A. The computed Coulomb sums are in complete
agreement with the latest analysis of the experimental data.Comment: 11 Latex pages, 2 ps figures. Talk delivered at the 10th
International Conference on Recent Progress In Many-Body Theories, Seattle
1999. To appear in "Advances in Quantum Many-Body Theory", vol.3, World
Scientifi
Boundary effects on radiative processes of two entangled atoms
We analyze radiative processes of a quantum system composed by two identical
two-level atoms interacting with a massless scalar field prepared in the vacuum
state in the presence of perfect reflecting flat mirrors. We consider that the
atoms are prepared in a stationary maximally entangled state. We investigate
the spontaneous transitions rates from the entangled states to the collective
ground state induced by vacuum fluctuations. In the empty-space case, the
spontaneous decay rates can be enhanced or inhibited depending on the specific
entangled state and changes with the distance between the atoms. Next, we
consider the presence of perfect mirrors and impose Dirichlet boundary
conditions on such surfaces. In the presence of a single mirror the transition
rate for the symmetric state undergoes a slight reduction, whereas for the
antisymmetric state our results indicate a slightly enhancement. Finally, we
investigate the effect of multiple reflections by two perfect mirrors on the
transition rates.Comment: submitted version to the journa
New Results in the CBF theory for medium-heavy nuclei
Momentum distributions, spectroscopic factors and quasi-hole wave functions
of medium-heavy doubly closed shell nuclei have been calculated in the
framework of the Correlated Basis Function theory, by using the Fermi
hypernetted chain resummation techniques. The calculations have been done by
using microscopic two-body nucleon-nucleon potentials of Argonne type, together
with three-body interactions. Operator dependent correlations, up to the tensor
channels, have been used.Comment: 6 pages, 3 figures, proceeding of the "XI Convegno su problemi di
Fisica Nucleare Teorica" 11-14 Ottobre 2006, Cortona, Ital
Entropy involved in fidelity of DNA replication
Information has an entropic character which can be analyzed within the
Statistical Theory in molecular systems. R. Landauer and C.H. Bennett showed
that a logical copy can be carried out in the limit of no dissipation if the
computation is performed sufficiently slowly. Structural and recent
single-molecule assays have provided dynamic details of polymerase machinery
with insight into information processing. We introduce a rigorous
characterization of Shannon Information in biomolecular systems and apply it to
DNA replication in the limit of no dissipation. Specifically, we devise an
equilibrium pathway in DNA replication to determine the entropy generated in
copying the information from a DNA template in the absence of friction. Both
the initial state, the free nucleotides randomly distributed in certain
concentrations, and the final state, a polymerized strand, are mesoscopic
equilibrium states for the nucleotide distribution. We use empirical stacking
free energies to calculate the probabilities of incorporation of the
nucleotides. The copied strand is, to first order of approximation, a state of
independent and non-indentically distributed random variables for which the
nucleotide that is incorporated by the polymerase at each step is dictated by
the template strand, and to second order of approximation, a state of
non-uniformly distributed random variables with nearest-neighbor interactions
for which the recognition of secondary structure by the polymerase in the
resultant double-stranded polymer determines the entropy of the replicated
strand. Two incorporation mechanisms arise naturally and their biological
meanings are explained. It is known that replication occurs far from
equilibrium and therefore the Shannon entropy here derived represents an upper
bound for replication to take place. Likewise, this entropy sets a universal
lower bound for the copying fidelity in replication.Comment: 25 pages, 5 figure
Einstein-AdS action, renormalized volume/area and holographic Rényi entropies
Indexación: Scopus.The authors thank D.E. Díaz, P. Sundell and A. Waldron for interesting discussions. C.A. is a Universidad Andres Bello (UNAB) Ph.D. Scholarship holder, and his work is supported by Dirección General de Investigación (DGI-UNAB). This work is funded in part by FONDECYT Grants No. 1170765 “Boundary dynamics in anti-de Sitter gravity and gauge/gravity duality ” and No. 3180620 “Entanglement Entropy and AdS gravity ”, and CONICYT Grant DPI 20140115.We exhibit the equivalence between the renormalized volume of asymptotically anti-de Sitter (AAdS) Einstein manifolds in four and six dimensions, and their renormalized Euclidean bulk gravity actions. The action is that of Einstein gravity, where the renormalization is achieved through the addition of a single topological term. We generalize this equivalence, proposing an explicit form for the renormalized volume of higher even-dimensional AAdS Einstein manifolds. We also show that evaluating the renormalized bulk gravity action on the conically singular manifold of the replica trick results in an action principle that corresponds to the renormalized volume of the regular part of the bulk, plus the renormalized area of a codimension-2 cosmic brane whose tension is related to the replica index. Renormalized Rényi entropy of odd-dimensional holographic CFTs can thus be obtained from the renormalized area of the brane with finite tension, including the effects of its backreaction on the bulk geometry. The area computation corresponds to an extremization problem for an enclosing surface that extends to the AdS boundary, where the newly defined renormalized volume is considered. © 2018, The Author(s).https://link.springer.com/article/10.1007%2FJHEP08%282018%2913
- …