8,313 research outputs found
Supersymmetric indices, defects and holography
No full textThis thesis explores the use of holography in the study of codimension-2 and codimension-4 defects of the 6d N = (2, 0) theories. By means of the Ryu-Takayanagi formula, we successfully determine various central charges associated to these defects, which play a crucial role in their full characterization. We also establish connections between different families of supergravity solutions, delivering a more comprehensive picture of their landscape.Another focus of this thesis is that of background conformal supergravity configurations for 4d N = 2 and 4d N = 4 SCFTs. The departure from the holographic tools is nevertheless an interesting one, as we are able to find such backgrounds that engineer various topological twists of the theories. Our results are novel in the context of N = 4,where we are able to construct the supercharges of the Vafa-Witten, Kapustin-Witten and half-twists, all valuable non-perturbative tools in the study of four-dimensional theories. Backgrounds for the N = 2 indices were already known, however, we provide a novel family of indices that interpolates exactly between the twisted index and a point on the moduli of Coulomb-branch indices; allowing us to equate the two.Finally, we introduce a novel realisation of defect-conformal-field-theories as finite-dimensional integrals over neural-networks. This construction extends the known formalism for CFTs to the defect case, providing a systematic framework for generating dCFT data from neural-network concatenations.<br/
Machine learning toric duality in brane tilings
No full textWe apply a variety of machine learning methods to the study of Seiberg duality within 4d \mathcal{N}=1 quantum field theories arising on the worldvolumes of D3-branes probing toric Calabi-Yau 3-folds. Such theories admit an elegant description in terms of bipartite tessellations of the torus known as brane tilings or dimer models. An intricate network of infrared dualities interconnects the space of such theories and partitions it into universality classes, the prediction and classification of which is a problem that naturally lends itself to a machine learning investigation. In this paper, we address a preliminary set of such enquiries. We begin by training a fully connected neural network to identify classes of Seiberg dual theories realised on \mathbb{Z}_m\times\mathbb{Z}_n orbifolds of the conifold and achieve R^2=0.988. Then, we evaluate various notions of robustness of our methods against perturbations of the space of theories under investigation, and discuss these results in terms of the nature of the neural network's learning. Finally, we employ a more sophisticated residual architecture to classify the toric phase space of the Y^{6,0} theories, and to predict the individual gauged linear \sigma-model multiplicities in toric diagrams thereof. In spite of the non-trivial nature of this task, we achieve remarkably accurate results; namely, upon fixing a choice of Kasteleyn matrix representative, the regressor achieves a mean absolute error of 0.021. We also discuss how the performance is affected by relaxing these assumptions
From large to small N = (4, 4) superconformal surface defects in holographic 6d SCFTs
No full textTwo-dimensional (2d) N = (4, 4) Lie superalgebras can be either ''small'' or ''large'', meaning their R-symmetry is either 𝔰𝔬(4) or 𝔰𝔬(4)⊕𝔰𝔬(4), respectively. Both cases admit a superconformal extension and fit into the one-parameter family 𝔡(2,1;γ)⊕𝔡(2,1;γ), with parameter γ∈(−∞,∞). The large algebra corresponds to generic values of γ, while the small case corresponds to a degeneration limit with γ→−∞. In 11d supergravity, we study known solutions with superisometry algebra 𝔡(2,1;γ)⊕𝔡(2,1;γ) that are asymptotically locally AdS_7 × S^4. These solutions are holographically dual to the 6d maximally superconformal field theory with 2d superconformal defects invariant under 𝔡(2,1;γ)⊕𝔡(2,1;γ). We show that a limit of these solutions, in which γ→−∞, reproduces another known class of solutions, holographically dual to small N = (4, 4) superconformal defects. We then use this limit to generate new small N = (4, 4) solutions with finite Ricci scalar, in contrast to the known small N = (4, 4) solutions. We then use holography to compute the entanglement entropy of a spherical region centered on these small N = (4, 4) defects, which provides a linear combination of defect Weyl anomaly coefficients that characterizes the number of defect-localized degrees of freedom. We also comment on the generalization of our results to include N = (0, 4) surface defects through orbifolding
Holographic Weyl anomalies for 4d defects in 6d SCFTs
No full textIn this note, we study 1/4- and 1/2-BPS co-dimension two superconformal defects in the 6d N=(2,0) AN−1 SCFT at large N using their holographic descriptions as solutions of 11d supergravity. In this regime, we are able to compute the defect contribution to the sphere entanglement entropy and the change in the stress-energy tensor one-point function due to the presence of the defect using holography. From these quantities, we are then able to unambiguously compute the values for two of the twenty-nine total Weyl anomaly coefficients that characterize 4d conformal defects in six and higher dimensions. We are able to demonstrate the consistency of the supergravity description of the defect theories with the average null energy condition on the field theory side. For each class of defects that we consider, we also show that the A-type Weyl anomaly coefficient is non-negative
J.C. Painter letter to Benjamin Lundy
No full textLetter from J.E. Painter to (presumably) Benjamin Lundy, answering a request for information about the history and operations of the Underground Railroad. Letter includes details of a story of an ex-slave transported on the Underground Railroad through Ohio and stories of the plight of other fugitive slaves crossing the Ohio River.
Benjamin Lundy (1789-1839) was a prominent Quaker abolitionist best known for his development of abolitionist periodicals. His "Genius of Universal Emancipation" was first published in 1821 from his home in Mt. Pleasant, Ohio, and enjoyed a wide circulation across the antebellum United States. In the 1820s, the young William Lloyd Garrison came to work for The Genius. Benjamin Lundy traveled widely seeking subscriptions to The Genius, giving talks about the anti-slavery movement, and observing and documenting the conditions of enslaved people across the Americas. He was also involved in the establishment of freed slave colonies in Mexico
Mexican land grant contract to Benjamin Lundy, March 10, 1835 (English)
No full textLegal document from an unsigned officer to Benjamin Lundy, authorizing him rights as empresario to a tract of land in then-Mexico. The document extends a previous treaty made to Lundy by the government of Mexico from November 17, 1823 -- presumably, this land is to be the site of Lundy's freed slave colony. Original Spanish-language document is also a part of this collection. Benjamin Lundy (1789-1839) was a prominent Quaker abolitionist best known for his development of abolitionist periodicals. His Genius of Universal Emancipation was first published in 1821 from his home in Mt. Pleasant, Ohio, and enjoyed a wide circulation across the antebellum United States. In the 1820s, the young William Lloyd Garrison came to work for The Genius. Benjamin Lundy traveled widely seeking subscriptions to The Genius, giving talks about the anti-slavery movement, and observing and documenting the conditions of enslaved people across the Americas. He was also involved in the establishment of freed slave colonies in Mexico
Eli Nichols letter to Benjamin Lundy, March 17th, 1839
No full textFriendly note from Eli Nichols to Benjamin Lundy covering topics in contemporary abolition, ranging from the social status of abolitionists to the oppression of the poor. Much of the letter concerns a review of contemporary social movements in equality-based education, including Shaker and Quaker communities. The letter concludes in discussion of Nichols' and Lundy's interest in forming a freed slave colony or community in then-Mexico, and describes the climate and culture of those regions in detail. Benjamin Lundy (1789-1839) was a prominent Quaker abolitionist best known for his development of abolitionist periodicals. His Genius of Universal Emancipation was first published in 1821 from his home in Mt. Pleasant, Ohio, and enjoyed a wide circulation across the antebellum United States. In the 1820s, the young William Lloyd Garrison came to work for The Genius. Benjamin Lundy traveled widely seeking subscriptions to The Genius, giving talks about the anti-slavery movement, and observing and documenting the conditions of enslaved people across the Americas. He was also involved in the establishment of freed slave colonies in Mexico
Mexican land grant contract to Benjamin Lundy, March 10, 1835 (Spanish)
No full textLegal document in Spanish from the government of Tamaulipas, Mexico, to Benjamin Lundy, which appears to grant Lundy the rights of empresario for his proposed colony for freed slaves in Tamaulipas. This document appears to be truncated; it ends abruptly after 2 pages. Collection also includes a period translation of this contract with Lundy in English, which appears to contain the full text of the agreement. Benjamin Lundy (1789-1839) was a prominent Quaker abolitionist best known for his development of abolitionist periodicals. His Genius of Universal Emancipation was first published in 1821 from his home in Mt. Pleasant, Ohio, and enjoyed a wide circulation across the antebellum United States. In the 1820s, the young William Lloyd Garrison came to work for The Genius. Benjamin Lundy traveled widely seeking subscriptions to The Genius, giving talks about the anti-slavery movement, and observing and documenting the conditions of enslaved people across the Americas. He was also involved in the establishment of freed slave colonies in Mexico
General Benjamin Butler Letter Regarding the naming of Newport News, Virginia
No full textDigital images of an original letter written by Former Union Major-General Benjamin Butler in reply to a query by author, Edwin Everett Hale on how Newport News, Virginia had received it's name. both sides of the original letter are included along with a typed transcription of the letter
Cinq années de voyage en Orient 1846-1851 par Israel-Joseph Benjamin II, voyageur et auteur, demeurant à Faltischan (Moldavie). Paris en vente chez Michel Levy Frères, rue Vivienne, 2 bis 1856 L' auteur se réserve le droit de traduction et de reproduction
No full textPreface: by Benjamin, J.Dedication: by the author to M.J. Altaras aîné de Marseille et M. Albert Cohn.Content description: Detailed contentsPagination: PP28+240PVolumes: 1Text Genre:Pros
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