Recursos de colección

Caltech Authors (143.226 recursos)

Repository of works by Caltech published authors.

Group = Walter Burke Institute for Theoretical Physics

Mostrando recursos 1 - 20 de 278

  1. Unifying Type II Supernova Light Curves with Dense Circumstellar Material

    Morozova, Viktoriya; Piro, Anthony L.; Valenti, Stefano
    A longstanding problem in the study of supernovae (SNe) has been the relationship between the Type IIP and Type IIL subclasses. Whether they come from distinct progenitors or they are from similar stars with some property that smoothly transitions from one class to another has been the subject of much debate. Here, using one-dimensional radiation-hydrodynamic SN models, we show that the multi-band light curves of SNe IIL are well fit by ordinary red supergiants surrounded by dense circumstellar material (CSM). The inferred extent of this material, coupled with a typical wind velocity of ~10-100 km s^(-1), suggests enhanced activity by...

  2. Refined large N duality for torus knots

    Kameyama, Masaya; Nawata, Satoshi
    We formulate large N duality of U(N) refined Chern-Simons theory with a torus knot/link in S^3. By studying refined BPS states in M-theory, we provide the explicit form of low-energy effective actions of Type IIA string theory with D4-branes on the Ω-background. This form enables us to relate refined Chern-Simons invariants of a torus knot/link in S^3 to refined BPS invariants in the resolved conifold. Assuming that the extra U(1) global symmetry acts on BPS states trivially, the duality predicts graded dimensions of cohomology groups of moduli spaces of M2-M5 bound states associated to a torus knot/link in the resolved conifold.

  3. Bulk Connectedness and Boundary Entanglement

    Bao, Ning; Remmen, Grant N.
    We prove, for any state in a conformal field theory defined on a set of boundary manifolds with corresponding classical holographic bulk geometry, that for any bipartition of the boundary into two non-clopen sets, the density matrix cannot be a direct product of the reduced density matrices on each region of the bipartition. In particular, there must be entanglement across the bipartition surface. We extend this no-go theorem to general, arbitrary partitions of the boundary manifolds into non-clopen parts, proving that the density matrix cannot be a direct product. This result gives a necessary condition for states to potentially correspond to holographic duals.

  4. New Kaluza-Klein Instantons and Decay of AdS Vacua

    Ooguri, Hirosi; Spodyneiko, Lev
    We construct a generalization of Witten's Kaluza-Klein instanton, where a higher-dimensional sphere (rather than a circle as in Witten's instanton) collapses to zero size and the geometry terminates at a bubble of nothing. We use the solution to exhibit instability of non-supersymmetric AdS_5 vacua in M Theory compactified on positive Kaehler-Einstein spaces, providing a further evidence for the recent conjecture that any non-supersymmetric anti-de Sitter vacuum supported by fluxes must be unstable.

  5. Quantum Circuit Cosmology: The Expansion of the Universe Since the First Qubit

    Bao, Ning; Cao, ChunJun; Carroll, Sean M.; McAllister, Liam
    We consider cosmological evolution from the perspective of quantum information. We present a quantum circuit model for the expansion of a comoving region of space, in which initially-unentangled ancilla qubits become entangled as expansion proceeds. We apply this model to the comoving region that now coincides with our Hubble volume, taking the number of entangled degrees of freedom in this region to be proportional to the de Sitter entropy. The quantum circuit model is applicable for at most 140 e-folds of inflationary and post-inflationary expansion: we argue that no geometric description was possible before the time t_1 when our comoving region was one Planck length across, and contained one...

  6. The analytic structure of conformal blocks and the generalized Wilson-Fisher fixed points

    Gliozzi, Ferdinando; Guerrieri, Andrea L.; Petkou, Anastasios C.; Wen, Congkao
    We describe in detail the method used in our previous work arXiv:1611.10344 to study the Wilson-Fisher critical points nearby generalized free CFTs, exploiting the analytic structure of conformal blocks as functions of the conformal dimension of the exchanged operator. Our method is equivalent to the mechanism of conformal multiplet recombination set up by null states. We compute, to the first non-trivial order in the epsilon-expansion, the anomalous dimensions and the OPE coefficients of infinite classes of scalar local operators using just CFT data. We study single-scalar and O(N)-invariant theories, as well as theories with multiple deformations. When available we agree with older results, but we also produce a wealth...

  7. Partial breakdown of quantum thermalization in a Hubbard-like model

    Garrison, James R.; Mishmash, Ryan V.; Fisher, Matthew P. A.
    We study the possible breakdown of quantum thermalization in a model of itinerant electrons on a one-dimensional chain without disorder, with both spin and charge degrees of freedom. The eigenstates of this model exhibit peculiar properties in the entanglement entropy, the apparent scaling of which is modified from a “volume law” to an “area law” after performing a partial, site-wise measurement on the system. These properties and others suggest that this model realizes a new, nonthermal phase of matter, known as a quantum disentangled liquid (QDL). The putative existence of this phase has striking implications for the foundations of quantum...

  8. Overhead analysis of universal concatenated quantum codes

    Chamberland, Christopher; Jochym-O'Connor, Tomas; Laflamme, Raymond
    We analyze the resource overhead of recently proposed methods for universal fault-tolerant quantum computation using concatenated codes. Namely, we examine the concatenation of the 7-qubit Steane code with the 15-qubit Reed-Muller code, which allows for the construction of the 49- and 105-qubit codes that do not require the need for magic state distillation for universality. We compute a lower bound for the adversarial noise threshold of the 105-qubit code and find it to be 8.33 × 10(−6). We obtain a depolarizing noise threshold for the 49-qubit code of 9.69 × 10(−4) which is competitive with the 105-qubit threshold result of...

  9. Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System

    De Wit, Julien; Lewis, Nikole K.; Knutson, Heather A.; Fuller, Jim; Antoci, Victoria; Fulton, Benjamin J.; Laughlin, Gregory; Deming, Drake; Shporer, Avi; Batygin, Konstantin; Cowan, Nicolas B.; Agol, Eric; Burrows, Adam S.; Fortney, Jonathan J.; Langton, Jonathan; Showman, Adam P.
    Extrasolar planets on eccentric short-period orbits provide a laboratory in which to study radiative and tidal interactions between a planet and its host star under extreme forcing conditions. Studying such systems probes how the planet's atmosphere redistributes the time-varying heat flux from its host and how the host star responds to transient tidal distortion. Here, we report the insights into the planet–star interactions in HAT-P-2's eccentric planetary system gained from the analysis of ~350 hr of 4.5 μm observations with the Spitzer Space Telescope. The observations show no sign of orbit-to-orbit variability nor of orbital evolution of the eccentric planetary...

  10. Exploring the nearly degenerate stop region with sbottom decays

    An, Haipeng; Gu, Jiayin; Wang, Lian-Tao
    A light stop with mass almost degenerate with the lightest neutralino has important connections with both naturalness and dark matter relic abundance. This region is also very hard to probe at colliders. In this paper, we demonstrate the potential of searching for such stop particles at the LHC from sbottom decays, focusing on two channels with final states 2ℓ + E^(miss)_T and 1bℓ + E^(miss)_T. We found that, if the lightest sbottom has mass around or below 1TeV and has a significant branching ratio to decay to stop and W (b → tW), a stop almost degenerate with neutralino can...

  11. Why Boltzmann Brains Are Bad

    Carroll, Sean M.
    Some modern cosmological models predict the appearance of Boltzmann Brains: observers who randomly fluctuate out of a thermal bath rather than naturally evolving from a low-entropy Big Bang. A theory in which most observers are of the Boltzmann Brain type is generally thought to be unacceptable, although opinions differ. I argue that such theories are indeed unacceptable: the real problem is with fluctuations into observers who are locally identical to ordinary observers, and their existence cannot be swept under the rug by a choice of probability distributions over observers. The issue is not that the existence of such observers is ruled out by data, but that the theories...

  12. Bootstrapping the Spectral Function: On the Uniqueness of Liouville and the Universality of BTZ

    Collier, Scott; Kravchuk, Petr; Lin, Ying-Hsuan; Yin, Xi
    We introduce spectral functions that capture the distribution of OPE coefficients and density of states in two-dimensional conformal field theories, and show that nontrivial upper and lower bounds on the spectral function can be obtained from semidefinite programming. We find substantial numerical evidence indicating that OPEs involving only scalar Virasoro primaries in a c>1 CFT are necessarily governed by the structure constants of Liouville theory. Combining this with analytic results in modular bootstrap, we conjecture that Liouville theory is the unique unitary c>1 CFT whose primaries have bounded spins. We also use the spectral function method to study modular constraints on CFT spectra, and discuss some implications of our...

  13. Axion detection via Topological Casimir Effect

    Cao, ChunJun; Zhitnitsky, Ariel R.
    We propose a new table-top experimental configuration for the direct detection of dark matter axions with mass in the (10^(−6) eV − 10^(−2)eV) range using non-perturbative effects in a system with non-trivial spatial topology. Different from most experimental setups found in literature on direct dark matter axion detection, which relies on ˙θ or ∇~ θ, we found that our system is in principle sensitive to a static θ ≥ 10^(−14) and can also be used to set limit on the fundamental constant θ_(QED) which becomes the fundamental observable parameter of the Maxwell system if some conditions are met. Connection with Witten effect when the induced electric charge...

  14. Generalized Wilson-Fisher Critical Points from the Conformal Operator Product Expansion

    Gliozzi, Ferdinando; Guerrieri, Andrea L.; Petkou, Anastasios C.; Wen, Congkao
    We study possible smooth deformations of the generalized free conformal field theory in arbitrary dimensions by exploiting the singularity structure of the conformal blocks dictated by the null states. We derive in this way, at the first nontrivial order in the ε expansion, the anomalous dimensions of an infinite class of scalar local operators, without using the equations of motion. In the cases where other computational methods apply, the results agree.

  15. Twisted gauge theories in three-dimensional Walker-Wang models

    Wang, Zitao; Chen, Xie
    Three-dimensional gauge theories with a discrete gauge group can emerge from spin models as a gapped topological phase with fractional point excitations (gauge charge) and loop excitations (gauge flux). It is known that 3D gauge theories can be “twisted,” in the sense that the gauge flux loops can have nontrivial braiding statistics among themselves and such twisted gauge theories are realized in models discovered by Dijkgraaf and Witten. A different framework to systematically construct three-dimensional topological phases was proposed by Walker and Wang and a series of examples have been studied. Can the Walker-Wang construction be used to realize the...

  16. An architecture for efficient multimodal gravitational wave parameter estimation with linear surrogate models

    O'Shaughnessy, Richard; Blackman, Jonathan; Field, Scott E.
    The recent direct detection of gravitational waves has further emphasized the need for fast, low-cost, and accurate methods to infer the parameters of gravitational wave sources. The performance of these calculations is limited by the cost of evaluating the likelihood function, due to expense in data handling and waveform generation. Building on recently developed surrogate models and a novel parameter estimation pipeline, we show how to quickly generate the likelihood function as a simple, analytic closed-form expression. Using a simple variant of a production-scale parameter estimation code, we demonstrate our method using surrogate models of effective-one-body and numerical relativity waveforms. Our study is the first time these models have...

  17. An architecture for efficient multimodal gravitational wave parameter estimation with linear surrogate models

    O'Shaughnessy, Richard; Blackman, Jonathan; Field, Scott E.
    The recent direct detection of gravitational waves has further emphasized the need for fast, low-cost, and accurate methods to infer the parameters of gravitational wave sources. The performance of these calculations is limited by the cost of evaluating the likelihood function, due to expense in data handling and waveform generation. Building on recently developed surrogate models and a novel parameter estimation pipeline, we show how to quickly generate the likelihood function as a simple, analytic closed-form expression. Using a simple variant of a production-scale parameter estimation code, we demonstrate our method using surrogate models of effective-one-body and numerical relativity waveforms. Our study is the first time these models have...

  18. Equation of State Effects on Gravitational Waves from Rotating Core Collapse

    Richers, S.; Ott, C. D.; Abdikamalov, E.; O'Connor, E.; Sullivan, C.
    Gravitational waves (GWs) generated by axisymmetric rotating collapse, bounce, and early postbounce phases of a galactic core-collapse supernova will be detectable by current-generation gravitational wave observatories. Since these GWs are emitted from the quadrupole-deformed nuclear-density core, they may encode information on the uncertain nuclear equation of state (EOS). We examine the effects of the nuclear EOS on GWs from rotating core collapse and carry out 1824 axisymmetric general-relativistic hydrodynamic simulations that cover a parameter space of 98 different rotation profiles and 18 different EOS. We show that the bounce GW signal is largely independent of the EOS and sensitive primarily to the ratio of rotational to gravitational energy, and...

  19. BPS spectra and 3-manifold invariants

    Gukov, Sergei; Pei, Du; Putrov, Pavel; Vafa, Cumrun
    We provide a physical definition of new homological invariants H_a(M_3) of 3-manifolds (possibly, with knots) labeled by abelian flat connections. The physical system in question involves a 6d fivebrane theory on M3 times a 2-disk, D^2, whose Hilbert space of BPS states plays the role of a basic building block in categorification of various partition functions of 3d N = 2 theory T[M3]: D^2 × S^1 half-index, S^2 × S^1 superconformal index, and S^2 × S^1 topologically twisted index. The first partition function is labeled by a choice of boundary condition and provides a refinement of Chern-Simons (WRT) invariant. A linear combination...

  20. Argyres-Douglas Theories, Chiral Algebras and Wild Hitchin Characters

    Fredrickson, Laura; Pei, Du; Yan, Wenbin; Ye, Ke
    We use Coulomb branch indices of Argyres-Douglas theories on S1×L(k,1) to quantize moduli spaces M_H of wild/irregular Hitchin systems. In particular, we obtain formulae for the "wild Hitchin characters" -- the graded dimensions of the Hilbert spaces from quantization -- for four infinite families of M_H, giving access to many interesting geometric and topological data of these moduli spaces. We observe that the wild Hitchin characters can always be written as a sum over fixed points in M_H under the U(1) Hitchin action, and a limit of them can be identified with matrix elements of the modular transform STkS in...

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