216051678
Entwinement and the emergence of spacetime
A bstractIt is conventional to study the entanglement between spatial regions of a quantum field theory. However, in some systems entanglement can be dominated by “internal”, possibly gauged, degrees of freedom that are not spatially organized, and that can give rise to gaps smaller than the inverse size of the system. In a holographic context, such small gaps are associated to the appearance of horizons and singularities in the dual spacetime. Here, we propose a concept of entwinement, which is intended to capture this fine structure of the wavefunction. Holographically, entwinement probes the entanglement shadow — the region of spacetime not probed by the minimal surfaces that compute spatial entanglement in the dual field theory. We consider the simplest example of this scenario — a 2d conformal field theory (CFT) that is dual to a conical defect in AdS3 space. Following our previous work, we show that spatial entanglement in the CFT reproduces spacetime geometry up to a finite distance from the conical defect. We then show that the interior geometry up to the defect can be reconstructed from entwinement that is sensitive to the discretely gauged, fractionated degrees of freedom of the CFT. Entwinement in the CFT is related to non-minimal geodesics in the conical defect geometry, suggesting a potential quantum information theoretic meaning for these objects in a holographic context. These results may be relevant for the reconstruction of black hole interiors from a dual field theory.
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.
17006831
Quiver topology and RG dynamics
Renormalization group flows of quiver gauge theories play a central role in determining the low-energy properties of string vacua. We demonstrate that useful predictions about the RG dynamics of a quiver gauge theory may be extracted from the global structure of its quiver diagram. For quiver theories of a certain type, we develop an efficient and practical method for determining which superpotential deformations generate a flow to an interacting conformal fixed point.
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.
119275275
Black holes as Rubik’s cubes
We propose a unitary toy model of black hole evaporation, in which the entanglement between the interior and exterior degrees of freedom vanishes at late times. Our model possesses the information-free property and satisfies the niceness conditions discussed in the literature. A key feature of the model is that the Hilbert space of black hole internal states contains a vacuum state corresponding to the completely evaporated black hole, which can be reached from any initial state via the Hawking process. Our model suggests a novel quantum cosmological way in which information can get out of an evaporating black hole.
118824876
Chiral three-point interactions in 5 and 6 dimensions
A bstractWe study $ \mathcal{N}=\left( {N,0} \right) $ super-Poincaré invariant six-dimensional massless and five-dimensional massive on-shell amplitudes. We demonstrate that in six dimensions, all possible three-point amplitudes involving self-dual tensor multiplets are necessarily embedded in gravitational theories. To obtain non-gravitational amplitudes, we study instead five-dimensional chiral massive amplitudes which can be considered as the KK reduction of six-dimensional chiral theories. We indeed find non-gravitational amplitudes whose on-shell degrees of freedom are shown to match those of the massive particle states that arise from self-dual strings wrapping a circle. Along the way we find interesting hints of a fermionic symmetry in the (2, 0) theory, which accompanies the self-dual tensor gauge symmetry. We also discuss novel theories with (3, 0) and (4, 0) supersymmetry.
14871446
Isotopic dependence of the caloric curve
Isotopic effects in projectile fragmentation at relativistic energies have been studied with the ALADIN forward spectrometer at SIS. Stable and radioactive Sn and La beams with an incident energy of 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 ratio of the produced spectator sources, consistent with predictions for expanded systems. Consequences for the proposed interpretation of chemical breakup temperatures as representing the limiting temperatures predicted by microscopic models are discussed.
53314925
Mass and Isospin Effects in Multifragmentation
A systematic study of isospin effects in the breakup of projectile spectators at relativistic energies has been performed with the ALADiN spectrometer at the GSI laboratory (Darmstadt). Four different projectiles 197 Au, 124 La, 124 Sn and 107 Sn, all with an incident energy of 600 AMeV, have been used, thus allowing a study of various combinations of masses and N/Z ratios in the entrance channel. The measurement of the momentum vector and of the charge of all projectile fragments with Z > 1 entering the acceptance of the ALADiN magnet has been performed with the high efficiency and resolution achieved with the TP-MUSIC IV detector. The Rise and Fall behavior of the mean multiplicity of IMFs as a function of Z bound and its dependence on the isotopic composition has been determined for the studied systems. Other observables investigated so far include mean N/Z values of the emitted light fragments and neutron multiplicities. Qualitative agreement has been obtained between the observed gross properties and the predictions of the Statistical Multifragmentation Model.
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.
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.