Non-global logarithms in jet and isolation cone cross sections

Starting from a factorization theorem in effective field theory, we derive a parton-shower equation for the resummation of non-global logarithms. We have implemented this shower and interfaced it with a tree-level event generator to obtain an automated framework to resum the leading logarithm of non-global observables in the large-$N_c$ limit. Using this setup, we compute gap fractions for dijet processes and isolation cone cross sections relevant for photon production. We compare our results with fixed-order computations and LHC measurements. We find that naive exponentiation is often not adequate, especially when the vetoed region is small, since non-global contributions are enhanced due to their dependence on the veto-region size. Since our parton shower is derived from first principles and based on renormalization-group evolution, it is clear what ingredients will have to be included to perform resummations at subleading logarithmic accuracy in the future.Comment: 39 pages, 13 figures. v2: journal version with new result (4.18) for narrow isolation cone

Why do firms opt for Alternative-Format Financial Statements ? Some Evidence from France

Historically, the format of financial statements has varied from one country to another. Recently, due to the attractiveness of their capital markets, the strength of their accounting professions and the influence of their institutional investors, Anglo-American countries have seen the impact of their accounting practices on other nations increase steadily, even influencing the actual format of financial statements. Given that French accounting regulations allow a certain degree of choice in consolidated balance sheet format (‘by nature’ or ‘by term’) and income statement format (‘by nature’ or ‘by function’), this study examines a sample of 199 large French listed firms in an attempt to understand why some of these firms do not use the traditional French formats (‘by nature’ for the balance sheet and ‘by nature” for the income statement), instead preferring Anglo-American practices (‘by term’ format for the balance sheet and ‘by function’ format for the income statement). We first analyze the balance sheet and income statement formats separately using a logit model, then combine the two and enrich the research design with a generalized ordered logit model and a multinomial logit regression. Our results confirm that the major driving factor behind the adoption of one or two alternative formats is the firm’s degree of internationalization, not only financial (auditor type, foreign listing and the decision to apply alternative accounting standards) but also commercial (company size and the internationalization of sales).Disclosure; Determinants; Financial Statements; Alternative format; France; Logit; Generalized ordered logit; Multinomial logit

Large Non-Planar Graphs and an Application to Crossing-Critical Graphs

We prove that, for every positive integer k, there is an integer N such that every 4-connected non-planar graph with at least N vertices has a minor isomorphic to K_{4,k}, the graph obtained from a cycle of length 2k+1 by adding an edge joining every pair of vertices at distance exactly k, or the graph obtained from a cycle of length k by adding two vertices adjacent to each other and to every vertex on the cycle. We also prove a version of this for subdivisions rather than minors, and relax the connectivity to allow 3-cuts with one side planar and of bounded size. We deduce that for every integer k there are only finitely many 3-connected 2-crossing-critical graphs with no subdivision isomorphic to the graph obtained from a cycle of length 2k by joining all pairs of diagonally opposite vertices.Comment: To appear in Journal of Combinatorial Theory B. 20 pages. No figures. Te

Logics of Imprecise Comparative Probability

This paper studies connections between two alternatives to the standard probability calculus for representing and reasoning about uncertainty: imprecise probability andcomparative probability. The goal is to identify complete logics for reasoning about uncertainty in a comparative probabilistic language whose semantics is given in terms of imprecise probability. Comparative probability operators are interpreted as quantifying over a set of probability measures. Modal and dynamic operators are added for reasoning about epistemic possibility and updating sets of probability measures

Factorization and Resummation for Jet Processes

From a detailed analysis of cone-jet cross sections in effective field theory, we obtain novel factorization theorems which separate the physics associated with different energy scales present in such processes. The relevant low-energy physics is encoded in Wilson lines along the directions of the energetic particles inside the jets. This multi-Wilson-line structure is present even for narrow-cone jets due to the relevance of small-angle soft radiation. We discuss the renormalization-group equations satisfied by these operators. Their solution resums all logarithmically enhanced contributions to such processes, including non-global logarithms. Such logarithms arise in many observables, in particular whenever hard phase-space constraints are imposed, and are not captured with standard resummation techniques. Our formalism provides the basis for higher-order logarithmic resummations of jet and other non-global observables. As a nontrivial consistency check, we use it to obtain explicit two-loop results for all logarithmically enhanced terms in cone-jet cross sections and verify those against numerical fixed-order computations.Comment: 59 pages, 15 figures. v2: journal version; v3: corrected sign of (5.11) and a few other typo

An Effective Field Theory for Jet Processes

Processes involving narrow jets receive perturbative corrections enhanced by logarithms of the jet opening angle and the ratio of the energies inside and outside the jets. Analyzing cone-jet processes in effective field theory, we find that in addition to soft and collinear fields their description requires degrees of freedom which are simultaneously soft and collinear to the jets. These collinear-soft particles can resolve individual collinear partons, leading to a complicated multi-Wilson-line structure of the associated operators at higher orders. Our effective field theory provides, for the first time, a factorization formula for a cone-jet process, which fully separates the physics at different energy scales. Its renormalization-group equations control all logarithmically enhanced higher-order terms, in particular also the non-global logarithms.Comment: 9 pages, 1 figure. v2: PRL versio

Deep Networks for Image Super-Resolution with Sparse Prior

Deep learning techniques have been successfully applied in many areas of computer vision, including low-level image restoration problems. For image super-resolution, several models based on deep neural networks have been recently proposed and attained superior performance that overshadows all previous handcrafted models. The question then arises whether large-capacity and data-driven models have become the dominant solution to the ill-posed super-resolution problem. In this paper, we argue that domain expertise represented by the conventional sparse coding model is still valuable, and it can be combined with the key ingredients of deep learning to achieve further improved results. We show that a sparse coding model particularly designed for super-resolution can be incarnated as a neural network, and trained in a cascaded structure from end to end. The interpretation of the network based on sparse coding leads to much more efficient and effective training, as well as a reduced model size. Our model is evaluated on a wide range of images, and shows clear advantage over existing state-of-the-art methods in terms of both restoration accuracy and human subjective quality

Signal-Jamming in a Sequential Auction

In a recurring auction early bids may reveal bidders’ types, which in turn affects bidding in later auctions. Bidders take this into account and may bid in a way that conceals their private information until the last auction is played. The present paper analyzes the equilibrium of a sequence of ?rst-price auctions assuming bidders have stable private values. We show that signal-jamming occurs and explore the dynamics of equilibrium prices.Auctions; Signaling; Price Competition

An Experiment in the Economic Consequences of Additional Disclosure: The Case of the Fair Value of Unlisted Equity Investments

We investigate the economic consequences of additional disclosure about assets with no active market in terms of liquidity, perception of information reliability and relevance. We use an experimental design: 181 MBA students are asked to value 24 investments. We manipulate the level of disclosure on the fair value of assets (Limited versus Full), the perception of expected profit (Gain versus Loss) and the firm's business risk (Low versus High). In the case of Limited (resp. Full) disclosure, participants are given a point estimate for the fair value of the investment (resp. plus a range of possible fair values). We find that in the Full disclosure situation, participants tend to make an offer more frequently, to bid prices lower than the fair value and to earn a lower return on their investments compared to the Limited disclosure case. These consequences vary with the environment (expected profit and risk).fair value; fair value measurement; disclosure; relevance; reliability; risk; SFAS 157; IFRS 7