Integrable boundary states in D3-D5 dCFT: beyond scalars

A D3-D5 intersection gives rise to a defect CFT, wherein the rank of the gauge group jumps by k units across a domain wall. The one-point functions of local operators in this set-up map to overlaps between on-shell Bethe states in the underlying spin chain and a boundary state representing the D5 brane. Focussing on the k=1 case, we extend the construction to gluonic and fermionic sectors, which was prohibitively difficult to achieve for k>1. As a byproduct, we test an all-loop proposal for the one-point functions in the su(2) sector at the half-wrapping order of perturbation theory.Comment: 30 pages, 3 figures; v2: distinction between asymptotic and wrapping contributions clarifie

Massive Conformal Symmetry and Integrability for Feynman Integrals

In the context of planar holography, integrability plays an important role for solving certain massless quantum field theories such as N=4 SYM theory. In this letter we show that integrability also features in the building blocks of massive quantum field theories. At one-loop order we prove that all massive n-gon Feynman integrals in generic spacetime dimensions are invariant under a massive Yangian symmetry. At two loops similar statements can be proven for graphs built from two n-gons. At generic loop order we conjecture that all graphs cut from regular tilings of the plane with massive propagators on the boundary are invariant. We support this conjecture by a number of numerical tests for higher loops and legs. The observed Yangian extends the bosonic part of the massive dual conformal symmetry that was found a decade ago on the Coulomb branch of N=4 SYM theory. By translating the Yangian level-one generators from dual to original momentum space, we introduce a massive generalization of momentum space conformal symmetry. Even for non-dual conformal integrals this novel symmetry persists. The Yangian can thus be understood as the closure of massive dual conformal symmetry and this new massive momentum space conformal symmetry, which suggests an interpretation via AdS/CFT. As an application of our findings, we bootstrap the hypergeometric building blocks for examples of massive Feynman integrals.Comment: 6 pages, v2: typos corrected, clarifications added, v3: minor improvements/corrections, title adapted to journal titl

Yangian Symmetry for Bi-Scalar Loop Amplitudes

We establish an all-loop conformal Yangian symmetry for the full set of planar amplitudes in the recently proposed integrable bi-scalar field theory in four dimensions. This chiral theory is a particular double scaling limit of gamma-twisted weakly coupled N=4 SYM theory. Each amplitude with a certain order of scalar particles is given by a single fishnet Feynman graph of disc topology cut out of a regular square lattice. The Yangian can be realized by the action of a product of Lax operators with a specific sequence of inhomogeneity parameters on the boundary of the disc. Based on this observation, the Yangian generators of level one for generic bi-scalar amplitudes are explicitly constructed. Finally, we comment on the relation to the dual conformal symmetry of these scattering amplitudes.Comment: 40 pages, 20 figure

Minimax estimation of the mode of functional data

Wir untersuchen den Modalwert einer Verteilung, die auf einem Funktionenraum wie etwa dem Raum integrierbarer Funktionen definiert ist. Die Definition des Modalwerts basiert auf Small-Ball-Wahrscheinlichkeiten. Wir benutzen Entropiemethoden wie etwa endliche Überdeckungen für die Definition eines Modalwertschätzers und die Beschreibung seines asymptotischen Verhaltens. Wir zeigen die starke Konsistenz und ermitteln die optimale Konvergenzrate für eine Klasse von Verteilungen, deren Modalwerte in einer totalbeschränkten Teilmenge des Funktionenraums liegen.We investigate the mode of a distribution defined on a function space, e.g. the space of integrable functions. We give a definition of the mode using small ball probabilities. We use entropy methods, e.g. finite covers, to define an estimator of the mode and to deduce its asymptotic behaviour. We show strong consistency and continue to derive the optimal rate of convergence over a class of distributions whose modes are contained in a totally bounded subset of the function space

Dear Guests, Please Pay for my License – Analyzing the Heterogenous Cost-Pass-Through of Commercial and Non-Commercial Rental Suppliers in Response to Regulatory Policies

Peer-to-peer rental markets have been shown to adversely impact the traditional hospitality industry and housing affordability, fueling the demand for regulation. While localities have implemented policies to address these issues, little is known about how rental suppliers respond to those regulations. Analyzing a policy implemented in New Orleans, which introduced annual bring-to-market costs while simultaneously banning listings from one city-center neighborhood, we reveal that hosts increase their prices as a result of the policy. We show that non-commercial hosts completely pass their additional costs onto their consumers. By contrast, commercial hosts with legalized listings located in the city center only partially pass on their costs to their guests, while decreasing prices in the rest of the city. Our results indicate that the policy falls short of reducing pressure on housing affordability in the city center, as peer-to-peer renting remains attractive when bring-to-market costs can easily be passed through to consumers

Overlaps and Fermionic Dualities for Integrable Super Spin Chains

The psu(2,2|4) integrable super spin chain underlying the AdS/CFT correspondence has integrable boundary states which describe set-ups where k D3-branes get dissolved in a probe D5-brane. Overlaps between Bethe eigenstates and these boundary states encode the one-point functions of conformal operators and are expressed in terms of the superdeterminant of the Gaudin matrix that in turn depends on the Dynkin diagram of the symmetry algebra. The different possible Dynkin diagrams of super Lie algebras are related via fermionic dualities and we determine how overlap formulae transform under these dualities. As an application we show how to consistently move between overlap formulae obtained for k=1 from different Dynkin diagrams.Comment: 34 pages, 8 figures; v2: a few clarifications adde

On the (Im-)Possibility of Extending Coin Toss

We consider the task of extending a given coin toss. By this, we mean the two-party task of using a single instance of a given coin toss protocol in order to interactively generate more random coins. A bit more formally, our goal is to generate n common random coins from a single use of an ideal functionality that gives m < n common random coins to both parties. In the framework of universal composability, we show the impossibility of securely extending a coin toss for statistical and perfect security. On the other hand, for computational security, the existence of a protocol for coin toss extension depends on the number m of random coins that can be obtained “for free.” For the case of stand-alone security, i.e., a simulation-based security definition without an environment, we present a protocol for statistically secure coin toss extension. Our protocol works for superlogarithmic m, which is optimal as we show the impossibility of statistically secure coin toss extension for smaller m. Combining our results with already known results, we obtain a (nearly) complete characterization under which circumstances coin toss extension is possible