4,921 research outputs found
A short note on a Bernstein-Bezier basis for the pyramid
We introduce a Bernstein-Bezier basis for the pyramid, whose restriction to
the face reduces to the Bernstein-Bezier basis on the triangle or
quadrilateral. The basis satisfies the standard positivity and partition of
unity properties common to Bernstein polynomials, and spans the same space as
non-polynomial pyramid bases in the literature.Comment: Submitte
Aspects of Track-Assisted Mass
Track-assisted mass is a proxy for jet mass that only uses direction
information from charged particles, allowing it to be measured at the Large
Hadron Collider with very fine angular resolution. In this paper, we introduce
a generalization of track-assisted mass and analyze its performance in both
parton shower generators and resummed calculations. For the original
track-assisted mass, the track-only mass is rescaled by the charged energy
fraction of the jet. In our generalization, the rescaling factor includes both
per-jet and ensemble-averaged information, facilitating a closer correspondence
to ordinary jet mass. Using the track function formalism in electron-positron
collisions, we calculate the spectrum of generalized track-assisted mass to
next-to-leading-logarithmic order with leading-order matching. These resummed
calculations provide theoretical insight into the close correspondence between
track-assisted mass and ordinary jet mass. With the growing importance of jet
grooming algorithms, we also calculate track-assisted mass on soft-drop groomed
jets.Comment: 35+17 pages, 22 figures; v3: improvements to calculation and
presentation to appear in JHE
Energy flow polynomials: A complete linear basis for jet substructure
We introduce the energy flow polynomials: a complete set of jet substructure
observables which form a discrete linear basis for all infrared- and
collinear-safe observables. Energy flow polynomials are multiparticle energy
correlators with specific angular structures that are a direct consequence of
infrared and collinear safety. We establish a powerful graph-theoretic
representation of the energy flow polynomials which allows us to design
efficient algorithms for their computation. Many common jet observables are
exact linear combinations of energy flow polynomials, and we demonstrate the
linear spanning nature of the energy flow basis by performing regression for
several common jet observables. Using linear classification with energy flow
polynomials, we achieve excellent performance on three representative jet
tagging problems: quark/gluon discrimination, boosted W tagging, and boosted
top tagging. The energy flow basis provides a systematic framework for complete
investigations of jet substructure using linear methods.Comment: 41+15 pages, 13 figures, 5 tables; v2: updated to match JHEP versio
Agricultural Arbitrage, Adjustment Costs, and the Intensive Margin
Farmland and capital are an important and rapidly expanding component of the agricultural economy, and empirical evidence suggests that these assets are quasi-fixed in that adjustment costs are incurred when holdings are altered. Increased interest in the rate of return for investing in farmland suggests that an important consideration is the effect of adjustment costs on this return. A novel theoretical model is developed that ties together contributions from the farmland pricing and adjustment cost literatures, and the first order conditions for a utility maximizing decision maker are rearranged into intertemporal arbitrage equations that are similar in spirit to traditional finance models. The common assumptions that land and capital are quasi-fixed assets, and that production is characterized by constant returns to scale are tested and the evidence supports these assumptions. An empirical application of the arbitrage equations provides evidence that risk aversion and adjustment costs are jointly significant components of agricultural production, and that adjustment costs generate significant changes in the rate of return to farmland. The results have important policy implications as sluggish supply response due to quasi-fixity can lead to dramatically inflated commodity prices, and an accurate measure of the farmland return can help determine how far the extensive margin will expand or contract in response to a variety of policy scenarios, such as the subsidization of corn for ethanol, an increase in the variety of subsidized crop insurance products, or the introduction of new revenue support programs such as ACRE.Arbitrage, Adjustment Costs, Farmland, Asset Pricing, Capital, Cost Function, Risk, Production, Agricultural Finance, Consumer/Household Economics, Crop Production/Industries, Farm Management, Financial Economics, Land Economics/Use, Production Economics, Risk and Uncertainty,
An operational definition of quark and gluon jets
While "quark" and "gluon" jets are often treated as separate, well-defined
objects in both theoretical and experimental contexts, no precise, practical,
and hadron-level definition of jet flavor presently exists. To remedy this
issue, we develop and advocate for a data-driven, operational definition of
quark and gluon jets that is readily applicable at colliders. Rather than
specifying a per-jet flavor label, we aggregately define quark and gluon jets
at the distribution level in terms of measured hadronic cross sections.
Intuitively, quark and gluon jets emerge as the two maximally separable
categories within two jet samples in data. Benefiting from recent work on
data-driven classifiers and topic modeling for jets, we show that the practical
tools needed to implement our definition already exist for experimental
applications. As an informative example, we demonstrate the power of our
operational definition using Z+jet and dijet samples, illustrating that pure
quark and gluon distributions and fractions can be successfully extracted in a
fully well-defined manner.Comment: 38 pages, 10 figures, 1 table; v2: updated to match JHEP versio
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