Quark and Gluon Tagging at the LHC

Being able to distinguish light-quark jets from gluon jets on an event-by-event basis could significantly enhance the reach for many new physics searches at the Large Hadron Collider. Through an exhaustive search of existing and novel jet substructure observables, we find that a multivariate approach can filter out over 95% of the gluon jets while keeping more than half of the light-quark jets. Moreover, a combination of two simple variables, the charge track multiplicity and the $p_T$-weighted linear radial moment (girth), can achieve similar results. While this pair appears very promising, our study is only Monte Carlo based, and other discriminants may work better with real data in a realistic experimental environment. To that end, we explore many other observables constructed using different jet sizes and parameters, and highlight those that deserve further theoretical and experimental scrutiny. Additional information, including distributions of around 10,000 variables, can be found on this website http://jets.physics.harvard.edu/qvg .Comment: 5 pages, 3 figures. v2 published versio

Factors Affecting Crop Insurance Purchase Decisions in Northern Illinois

When making crop insurance purchase decisions, farmers must consider multiple factors. This paper examines such factors through the use of a survey conducted in a 42 county region of Northern Illinois during 2005. Participants were asked who most influenced their crop insurance purchase decision and if the availability of a Premium Discount Plan (PDP) affected their decision. Respondents indicated that they generally made crop insurance purchase decisions independently, and that the availability of a PDP influenced about 25% of the decisions made. Questions about the importance of ten specific purchase factors were also asked in two distinct groups of five factors each. In one group of factors, price of the insurance was found to be more important than the probability of receiving a claim payment. The other group of factors revealed that government subsidization of premium and weather concerns were highly important to survey participants. Results have also been summarized according to the risk attitude of respondents. Crop insurance participation, plan and coverage level, and other demographic data were collected as well. Further analysis will be conducted to determine relationships between purchase decision factors and the characteristics of the respondents.Risk and Uncertainty,

Credit Line Availability and Utilization in REITs

Analysis of REIT credit line availability and use under normal conditions and during the recent financial crisis are provided. Descriptive statistics indicate REIT credit lines represent an important component of capital structure, credit line availability and utilization have increased substantially over the sample period, and REITs maintain precautionary liquidity via credit lines rather than holding cash. Multivariate results indicate that credit line availability is directly associated with cash flow uncertainty, dividend distributions, acquisitions, and capital market access and is inversely linked to the market-to-book ratio. Credit line use is unrelated to cash flow volatility and dividends, but is correlated with operating cash flow, acquisitions, and capital market access. Unlike with non-REITs, when setting credit limits lenders focus on dividends and not just operating cash flow. Despite finding that line availability is influenced by dividend payments, REITs do not systematically use lines to pay dividends implying that dividends are paid from operating cash flows.

Productivity Growth in the 1990s: Technology, Utilization, or Adjustment?

Measured productivity growth increased substantially during the second half of the 1990s. This paper examines whether this increase owes to an increase in the rate of technological change or whether it can be explained by non-technological factors relating to factor utilization, factor accumulation, or returns to scale. It finds that the recent increase in productivity growth does appear to arise from an increase in technological change. Cyclical utilization raised measured productivity growth relative to technology growth in the first part of the expansion, but lowered it subsequently. Factor adjustment leads to a steady-state understatement of technology growth by measured productivity growth. The understatement was greater in the second half of the expansion than the first. Changes in the distribution of inputs across industries with different returns to scale lead to a modest understatement in the growth in technology. Although the increase technological change is most pronounced in durable manufacturing, technological change also increased outside of manufacturing.

Productivity growth in the 1990s: technology, utilization, or adjustment

Measured productivity growth increased substantially during the second half of the 1990s. This paper examines whether this increase owes to an increase in the rate of technological change or whether it can be explained by non-technological factors relating to factor utilization, factor accumulation, or returns to scale. It finds that the recent increase in productivity growth does appear to arise from an increase in technological change. Cyclical utilization raised measured productivity growth relative to technology growth in the first part of the expansion, but lowered it subsequently. Factor adjustment leads to a steady-state understatement of technology growth by measured productivity growth. The understatement was greater in the second half of the expansion than the first. Changes in the distribution of inputs across industries with different returns to scale lead to a modest understatement in the growth in technology. Although the increase technological change is most pronounced in durable manufacturing, technological change also increased outside of manufacturing.Productivity ; Technology ; Manufactures