117771864
Holographic definition of points and distances
We discuss the way in which field theory quantities assemble the spatial geometry of three-dimensional anti\char21{}de Sitter space (${\mathrm{AdS}}_{3}$). The field theory ingredients are the entanglement entropies of boundary intervals. A point in ${\mathrm{AdS}}_{3}$ corresponds to a collection of boundary intervals which is selected by a variational principle we discuss. Coordinates in ${\mathrm{AdS}}_{3}$ are integration constants of the resulting equation of motion. We propose a distance function for this collection of points, which obeys the triangle inequality as a consequence of the strong subadditivity of entropy. Our construction correctly reproduces the static slice of ${\mathrm{AdS}}_{3}$ and the Ryu-Takayanagi relation between geodesics and entanglement entropies. We discuss how these results extend to quotients of ${\mathrm{AdS}}_{3}$\char22{}the conical defect and the BTZ geometries. In these cases, the set of entanglement entropies must be supplemented by other field theory quantities, which can carry the information about lengths of nonminimal geodesics.
84181918
Bulk curves from boundary data in holography
We embed spherical Rindler space—a geometry with a spherical hole in its center—in asymptotically anti– de Sitter (AdS) spacetime and show that it carries a gravitational entropy proportional to the area of the hole. Spherical AdS-Rindler space is holographically dual to an ultraviolet sector of the boundary field theory given by restriction to a strip of finite duration in time. Because measurements have finite durations, local observers in the field theory can only access information about bounded spatial regions. We propose a notion of differential entropy that captures uncertainty about the state of a system left by the collection of local, finite-time observables. For two-dimensional conformal field theories we use holography and the strong subadditivity of entanglement to propose a formula for differential entropy and show that it precisely reproduces the areas of circular holes in AdS3. Extending the notion to field theories on strips with variable durations in time, we show more generally that differential entropy computes the areas of all closed, inhomogeneous curves on a spatial slice of AdS3. We discuss the extension to higher-dimensional field theories, the relation of differential entropy to entanglement between scales, and some implications for the emergence of space from the renormalization group flow of entangled field theories.
118485314
A novel channel for vacuum decay
Abstract I show that cosmological bubble walls in the thin wall approximation are unstable to the creation of “barnacles” – loci of different wall tension adjacent to regions filled with a third vacuum. Barnacle formation appears to have the same observational consequences as the extensively studied bubble collision scenario, but occurs exponentially more often. The process is described by a saddle point of the thin wall action with two negative modes.
16140829
Typicality versus thermality: an analytic distinction
In systems with a large degeneracy of states such as black holes, one expects that the average value of probe correlation functions will be well approximated by the thermal ensemble. To understand how correlation functions in individual microstates differ from the canonical ensemble average and from each other, we study the variances in correlators. Using general statistical considerations, we show that the variance between microstates will be exponentially suppressed in the entropy. However, by exploiting the analytic properties of correlation functions we argue that these variances are amplified in imaginary time, thereby distinguishing pure states from the thermal density matrix. We demonstrate our general results in specific examples and argue that our results apply to the microstates of black holes.
118461064
The Grainy multiverse
I consider a landscape containing three vacua and study the topology of global spacelike slices in eternal inflation. A discrete toy model, which generalizes the well studied Mandelbrot model, reveals a rich phase structure. Novel phases include monochromatic tubular phases, which contain crossing curves of only one vacuum, and a democratic tubular phase, which contains crossing curves of all three types of vacua. I discuss the generalization to realistic landscapes consisting of many vacua. Generically, the system ends up in a grainy phase, which contains no crossing curves or surfaces and consists of packed regions of different vacua. Other topological phases arise on the scale of several generations of nucleations.
15617697
Trace Anomaly in Geometric Discretization
I develop the simplest geometric-discretized analogue of two dimensional scalar field theory, which qualitatively reproduces the trace anomaly of the continuous theory. The discrete analogue provides an interpretation of the trace anomaly in terms of a non-trivial transformation of electric-magnetic duality-invariant modes of resistor networks that accommodate both electric and magnetic charge currents.
14231355
Discriminant analysis and secondary-beam charge recognition
The discriminant-analysis method has been applied to optimize the exotic-beam charge recognition in a projectile fragmentation experiment. The experiment was carried out at the GSI using the fragment separator (FRS) to produce and select the relativistic secondary beams, and the ALADIN setup to measure their fragmentation products following collisions with Sn target nuclei. The beams of neutron poor isotopes around La-124 and Sn-107 were selected to study the isospin dependence of the limiting temperature of heavy nuclei by comparing with results for stable Sn-124 projectiles. A dedicated detector to measure the projectile charge upstream of the reaction target was not used, and alternative methods had to be developed. The presented method, based on the multivariate discriminant analysis, allowed to increase the efficacy of charge recognition up to about 90%, which was about 20% more than achieved with the simple scalar methods.
7513198
Time scale of the thermal multifragmentation in p(3.6 GeV) + Au collisions
The relative angle correlation of intermediate mass fragments has been studied for p+Au collisions at 3.6 GeV. Strong suppression at small angles is observed caused by IMF-IMF Coulomb repulsion. Experimental correlation function is compared to that obtained by the multi-body Coulomb trajectory calculations with the various decay time of fragmenting system. The combined model including the empirically modified intranuclear cascade followed by statistical multifragmentation was used to generate starting conditions for these calculations. The model dependence of the results obtained has been carefully checked. The mean decay time of fragmenting system is found to be 85 +- 50 fm/c.
109634219
Heavy-ion test of detectors with conventional and resistive Micromegas used in TPC configuration
Abstract We have performed tests of Micromegas detector prototypes using the heavy-ion beams from the SIS synchrotron of GSI (Darmstadt, Germany). The beams varied from C 6 + 12 to Au 65 + 179 and from 250 to 1000 MeV per nucleon. We have tested two amplification technologies, conventional and resistive Micromegas, and two construction concepts, bulk-Micromegas and micro-meshes screwed on the PCB. The obtained position resolution below 200 μ m for 5 mm wide strips implies that the bulk resistive Micromegas technology might meet the requirements of the future R3B TPC project. We also developed a fast and very low noise front-end electronics connected directly to the Printed Circuit Board (PCB) of the detector itself. This concept has shown very good performances and robustness.
28982415
Isotopic dependence of the nuclear caloric curve.
The A/Z dependence of projectile fragmentation at relativistic energies has been studied with the ALADIN forward spectrometer at SIS. A stable beam of (124)Sn and radioactive beams of (124)La and (107)Sn at 600 MeV per nucleon have been used in order to explore a wide range of isotopic compositions. Chemical freeze-out temperatures are found to be nearly invariant with respect to the A/Z of the produced spectator sources, consistent with predictions for expanded systems. Small Coulomb effects (DeltaT approximately 0.6 MeV) appear for residue production near the onset of multifragmentation.
118568605
Mass and isospin dependence in multifragmentation
Challenging motivations for isotopic studies in nuclear multifragmentation are derived from the the importance of the density dependence of the symmetry term of the nuclear equation of state for astrophysical applications and for effects linked to the manifestation of the nuclear liquid-gas phase transition. In a recent experiment with the ALADIN spectrometer at GSI, the possibility of using secondary beams for reaction studies at relativistic energies has been explored. Beams of $^{107}$Sn, $^{124}$Sn, $^{124}$La, and $^{197}$Au were used to investigate the mass and isospin dependence of multifragmentation. The status of the project and first results are reported and discussed.