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6,070 research outputs found

Why Are Neutrinos Light? -- An Alternative

Author: Hall Lawrence J.
Oliver Steven J.
Publication venue: 'Elsevier BV'
Publication date: 23/09/2004
Field of study

We review the recent proposal that neutrinos are light because their masses are proportional to a low scale, f, of lepton flavor symmetry breaking. This mechanism is testable because the resulting pseudo-Goldstone bosons, of mass m_G, couple strongly with the neutrinos, affecting the acoustic oscillations during the eV era of the early universe that generate the peaks in the CMB radiation. Characteristic signals result over a very wide range of (f, m_G) because of a change in the total relativistic energy density and because the neutrinos scatter rather than free-stream. Thermodynamics allows a precise calculation of the signal, so that observations would not only confirm the late-time neutrino mass mechanism, but could also determine whether the neutrino spectrum is degenerate, inverted or hierarchical and whether the neutrinos are Dirac or Majorana. The flavor symmetries could also give light sterile states. If the masses of the sterile neutrinos turn on after the MeV era, the LSND oscillations can be explained without upsetting big bang nucleosynthesis, and, since the sterile states decay to lighter neutrinos and pseudo-Goldstones, without giving too much hot dark matter.Comment: Talk given by LJH at the Fujihara Seminar on Neutrino Mass and Seesaw Mechanism held at KEK, Japan, February 2004. 11 pages, 1 figure, 3 table

arXiv.org e-Print Archive

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UNT Digital Library

Impact of row spacing/planting pattern and seed size on plant development and yield on cotton (Gossypium hirsutum L.).

Author: Hall Steven Dale
Hall Steven Dale
Publication venue: Scholars Junction
Publication date: 13/05/2022
Field of study

There is renewed interest in cotton performance grown using various row spacings and plantings patterns in the Midsouth. Cotton seed size has been reduced compared to sixty years ago. Planting smaller seeds is concerning due to having less energy for emergence as well as complicating the ginning process. Two row spacings, two planting patterns, and two cotton varieties were evaluated over eight site years from 2019-2020. The solid planting pattern produced a higher yield on a land area basis. In addition, two varieties, each with three seed counts, were planted at three seeding rates and evaluated over six site years from 2019-2020. Greater seedcotton yields were observed from larger seed sizes and higher seeding rates. Row spacing had no impact on yield but depending on input cost, a 2x1 skip pattern could be beneficial. Also, higher seeding rates and larger seeds maximized yields

Scholars Junction - Mississippi State University Institutional Repository

Risk-Based Capital Standards and the Riskiness of Bank Portfolios: Credit and Factor Risks

Author: Brian J. Hall
Steven R. Grenadier
Publication venue
Publication date
Field of study

Bank risk-based capital (RBC) standards require banks to hold differing amounts of capital for different classes of assets, based almost entirely on a credit risk criterion. The paper provides both a theoretical and empirical framework for evaluating such standards. A model outlining a pricing methodology for loans subject to default risk is presented. The model shows that the returns on such loans are affected by the complicated interaction of the likelihood of default, the consequences of default, term structure variables, and the pricing of factor risks in the economy. When we examine whether the risk weights accurately reflect bank asset risk, we find that the weights fail even in their limited goal of correctly quantifying credit risk. For example, our findings indicate that the RBC weights overpenalize home mortgages, which have an average credit loss of 13 basis points, relative to commercial and consumer loans. The RBC rules also contain a significant bias against direct mortgages relative to mortgage- backed securities. In addition, we find large differences in the credit riskiness of loans within the 100 percent weight class and potentially large benefits to loan diversification, neither of which are considered in the RBC regulations. We also examine other types of bank risk by estimating a simple factor model that decomposes loan risk into term structure, default, and market risk. One implication of our findings is that although banks have reallocated their portfolios in ways intended by the RBC standards, they may have merely substituted one type of risk (term structure risk) for others (default and market risk), of which the net effect is unknown.

Research Papers in Economics