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A bstract We study causality in gravitational systems beyond the classical limit. Using on-shell methods, we consider the 1-loop corrections from charged particles to the photon energy-momentum tensor — the self-stress — that controls the quantum interaction between two on-shell photons and one off-shell graviton. The self-stress determines in turn the phase shift and time delay in the scattering of photons against a spectator particle of any spin in the eikonal regime. We show that the sign of the β -function associated to the running gauge coupling is related to the sign of time delay at small impact parameter. Our results show that, at first post-Minkowskian order, asymptotic causality, where the time delay experienced by any particle must be positive, is respected quantum mechanically. Contrasted with asymptotic causality, we explore a local notion of causality, where the time delay is longer than the one of gravitons, which is seemingly violated by quantum effects.

A bstract Key to the simplicity of supergravity α -attractor models of inflation are Volkov-Akulov fermions, often in the form of nilpotent superfields. Here we explore the possibility of using the double-copy to construct theories of Dirac-Born-Infeld-Volkov-Akulov (DBIVA) coupled to supergravity. A color-dual bootstrap admits scattering amplitudes involving pions and vectors through five-point tree-level order by order in mass-dimension, but requires the introduction of a Tr( F 3 ) operator. Gauge theories with this operator were recently found to require a tower of higher-derivative operators to be compatible with the duality between color and kinematics. Adjoint-type double-copy construction at its most conservative seems to require the UV completion of DBIVA + pure Poincaré supergravity scattering amplitudes to a family of theories involving DBIVA-like particles coupled to Weyl-Einstein supergravity. We also point out an alternative solution to color-dual gauged pions that allows adjoint double-copy without a tower of higher derivative corrections but at the cost of exchange symmetry between scalars.

A bstract We analyze the signatures of inflationary models that are coupled to interacting field theories, a basic class of multifield models also motivated by their role in providing dynamically small scales. Near the squeezed limit of the bispectrum, we find a simple scaling behavior determined by operator dimensions, which are constrained by the appropriate unitarity bounds. Specifically, we analyze two simple and calculable classes of examples: conformal field theories (CFTs), and large-N CFTs deformed by relevant time-dependent double-trace operators. Together these two classes of examples exhibit a wide range of scalings and shapes of the bispectrum, including nearly equilateral, orthogonal and local non-Gaussianity in different regimes. Along the way, we compare and contrast the shape and amplitude with previous results on weakly coupled fields coupled to inflation. This signature provides a precision test for strongly coupled sectors coupled to inflation via irrelevant operators suppressed by a high mass scale up to ~ 10 3 times the inflationary Hubble scale.

A bstract We make an extension to recent calculations of the probability density ρ ( V ) for the volume of the universe after inflation. Previous results have been accurate to leading order in the slow roll parameters ∈ ≡ H ⋅ / H 2 and η ≡ ϕ ⋅⋅ / ϕ ⋅ H , and 1 /N c , where H is the Hubble parameter and N c is the classical number of e -foldings. Here, we present a modification which captures effects of order ϵN c , which amounts to letting the parameters of inflation H and ϕ ⋅ depend on the value of the inflaton ϕ . The phase of slow roll eternal inflation can be defined as when the probability to have an infinite volume is greater than zero. Using this definition, we study the Laplace transform of ρ ( V ) numerically to determine the condition that triggers the transition to eternal inflation. We also study the average volume 〈 V 〉 analytically and show that it satisfies the universal volume bound. This bound states that, in any realization of inflation which ends with a finite volume, an initial volume must grow by less than a factor of e S d S / 2 , where S dS is the de Sitter (dS) entropy.

Over the last two decades or so, VLSI hardware is increasingly subject to sophisticated attacks on both the supply chain and design fronts. There is no explicit trust that the manufacturers/providers are not producing counterfeit designs or that cryptographic algorithms we know to be secure in software are also secure in hardware. The novelty and key contributions of this work are as follows: 1) a continually refined method for Intellectual Property (IP) Protection that provides an approach for verification of IP ownership, 2) demonstrate how to break the PRESENT-80 cryptographic algorithm with significantly limited resources, and 3) provide a multitude of hardware based countermeasures to counter such attacks. First, in order to thwart intellectual property theft, the proposed state encoding based watermarking method and the mapping algorithm outperforms the prior techniques. We propose a hybrid genetic algorithm, dubbed the Darwinian Genetic Algorithm, for efficiently solving the difficult sub-graph matching problem. As a result, we outperformed prior work maximally 20–30% and on average 1–12% when considering the post-synthesis watermarked designs in terms of literals, area, and delay. Second, we demonstrate for the first time ever how the lightweight cryptographic algorithm PRESENT-80 can be broken via a Differential Plaintext Attack with significantly limited resources. Lastly, to prevent such attacks, we present a series of countermeasures to not only PRESENT-80, but for all substitution-permutation network ciphers, by inducing non-static behavior. We present novel interconnection network primitives, dynamic routing networks, and ultimately modify round invariant items to round based variants that necessitate decision making for an attacker.

Here, we analyze the signatures of inflationary models that are coupled to interacting field theories, a basic class of multifield models also motivated by their role in providing dynamically small scales. Near the squeezed limit of the bispectrum, we find a simple scaling behavior determined by operator dimensions, which are constrained by the appropriate unitarity bounds. Specifically, we analyze two simple and calculable classes of examples: conformal field theories (CFTs), and large-N CFTs deformed by relevant time-dependent double-trace operators. Together these two classes of examples exhibit a wide range of scalings and shapes of the bispectrum, including nearly equilateral, orthogonal and local non-Gaussianity in different regimes. Along the way, we compare and contrast the shape and amplitude with previous results on weakly coupled fields coupled to inflation. This signature provides a precision test for strongly coupled sectors coupled to inflation via irrelevant operators suppressed by a high mass scale up to 103 times the inflationary Hubble scale.

We study infrared effects in perturbation theory for large-scale structure coupled to the effective field theory of dark energy, focusing on, in particular, Degenerate Higher-Order Scalar-Tensor (DHOST) theories. In the subhorizon, Newtonian limit, DHOST theories introduce an extra large-scale velocity \\(v^i_\\pi\\) which is in general different from the matter velocity \\(v^i\\). Contrary to the case in Horndeski theories, the presence of this extra large-scale velocity means that one cannot eliminate the long-wavelength effects of both \\(v^i\\) and \\(v^i_\\pi\\) with a single coordinate transformation, and thus the standard \\(\\Lambda\\)CDM consistency relations for large-scale structure are violated by terms proportional to the relative velocity \\(v^i - v^i_\\pi\\). We show, however, that in non-linear quantities this violation is determined by the linear equations and the symmetries of the fluid system. We find that the size of the baryon acoustic oscillations in the squeezed limit of the bispectrum is modified, that the bias expansion contains extra terms which contribute to the squeezed limit of the galaxy bispectrum, that infrared modes in the one-loop power spectrum no longer cancel, and that the equal-time double soft limit of the tree-level trispectrum is non-vanishing. In addition, we give explicit expressions for how these violations depend on the relative velocity. Many of our computations are also relevant for perturbation theory in \\(\\Lambda\\)CDM with exact time dependence.

We show that it is possible to directly measure the formation time of galaxies using large-scale structure. In particular, we show that the large-scale distribution of galaxies is sensitive to whether galaxies form over a narrow period of time before their observed times, or are formed over a time scale on the order of the age of the Universe. Along the way, we derive simple recursion relations for the perturbative terms of the most general bias expansion for the galaxy density, thus fully extending the famous dark-matter recursion relations to generic tracers.

We derive the kernels and the Effective Field Theory of Large-Scale Structure counterterms for the one-loop bispectrum of dark matter and of biased tracers in real and redshift space. This requires the expansion of biased tracers up to fourth order in fluctuations. In the process, we encounter several subtleties related to renormalization. One is the fact that, in renormalizing the momentum, a local counterterm contributes non-locally. A second subtlety is related to the renormalization of local products of the velocity fields, which need to be expressed in terms of the renormalized velocity in order to preserve Galilean symmetry. We check that the counterterms we identify are necessary and sufficient to renormalize the one-loop bispectrum at leading and subleading order in the derivative expansion. The kernels that we originally present here have already been used for the first analyses of the one-loop bispectrum in BOSS data [1, 2].

We present an Intellectual Property (IP) protection technique for sequential circuits driven by embedding a decomposed signature into a Finite State Machine (FSM) through the manipulation of the arbitrary state encoding of the unprotected FSM. This technique is composed of three steps: (a) transforming the signature into a watermark graph, (b) embedding watermark graphs into the original FSM's State Transition Graph (STG) and (c) generating models for verification and extraction. In the watermark construction process watermark graphs are generated from signatures. The proposed methods for watermark construction are: (1) BSD, (2) FSD, and (3) HSD. The HSD method is shown to be advantageous for all signatures while providing sparse watermark FSMs with complexity [special characters omitted](n2). The embedding process is related to the sub-graph matching problem. Due to the computational complexity of the matching problem, attempts to reverse engineer or remove the constructed watermark from the protected FSM, with only finite resources and time, are shown to be infeasible. The proposed embedding solutions are: (1) Brute Force and (2) Greedy Heuristic. The greedy heuristic has a computational complexity of [special characters omitted](n log n), where n is the number of states in the watermark graph. The greedy heuristic showed improvements for three of the six encoding schemes used in experimental results. Model generation and verification utilizes design automation techniques for generating multiple representations of the original, watermark, and watermarked FSMs. Analysis of the security provided by this method shows that a variety of attacks on the watermark and system including: (1) data-mining hidden functionality, (2) preimage, (3) secondary preimage, and (4) collision, can be shown to be computationally infeasible. Experimental results for the ten largest IWLS 93 benchmarks that the proposed watermarking technique is a secure, yet flexible, technique for protecting sequential circuit based IP cores.