Fully double-logarithm-resummed cross sections

We calculate the complete double logarithmic contribution to cross sections for semi-inclusive hadron production in the modified minimal-subtraction scheme by applying dimensional regularization to the double logarithm approximation. The full double logarithmic contribution to the coefficient functions for inclusive hadron production in electron-positron annihilation is obtained in this scheme for the first time. Our result agrees with all fixed order results in the literature, which extend to next-next-to-leading order.Comment: To appear in Nuclear Physics

An Energy Feedback System for the MIT/Bates Linear Accelerator

We report the development and implementation of an energy feedback system for the MIT/Bates Linear Accelerator Center. General requirements of the system are described, as are the specific requirements, features, and components of the system unique to its implementation at the Bates Laboratory. We demonstrate that with the system in operation, energy fluctuations correlated with the 60 Hz line voltage and with drifts of thermal origin are reduced by an order of magnitude

A High Power Hydrogen Target for Parity Violation Experiments

Parity-violating electron scattering measurements on hydrogen and deuterium, such as those underway at the Bates and CEBAF laboratories, require luminosities exceeding $10^{38}$cm$^{-2}$s$^{-1}$, resulting in large beam power deposition into cryogenic liquid. Such targets must be able to absorb 500 watts or more with minimal change in target density. A 40~cm long liquid hydrogen target, designed to absorb 500~watts of beam power without boiling, has been developed for the SAMPLE experiment at Bates. In recent tests with 40~$\mu$A of incident beam, no evidence was seen for density fluctuations in the target, at a sensitivity level of better than 1\%. A summary of the target design and operational experience will be presented.Comment: 13 pages, 9 postscript figure

Hospitalization and Mortality Outcomes among Childhood Cancer Survivors by Race, Ethnicity, and Time since Diagnosis

Importance: Cancer outcomes are relatively poor in adults who belong to minoritized racial and ethnic groups. Survival and long-term outcomes by race and ethnicity in individuals with childhood cancers are less studied. Objective: To evaluate survival and hospitalization among American Indian and Alaska Native, Asian, Black, and Hispanic children compared with non-Hispanic White children with cancer. Design, Setting, and Participants: This cohort study evaluated all individuals born in Washington State who were younger than 20 years (hereafter referred to as children) and had been diagnosed with cancer during 1987 to 2012, with follow-up ranging from 1 to 27 years. The data subset was built in 2019, and statistical analyses were completed in January 2022. Exposures: Race and ethnicity. Main Outcomes and Measures: Mortality and hospitalization events for all other racial and ethnic groups relative to non-Hispanic White children estimated by Cox proportional hazards regressions for the first 5 years after diagnosis and among cancer survivors 5 or more years after diagnosis. Results: A total of 4222 children (mean [SD] age, 8.4 [6.4] years; 2199 [52.1%] male; 113 American Indian and Alaska Native [2.7%], 311 Asian [7.4%], 196 Black [4.6%], 387 Hispanic [9.2%], and 3215 non-Hispanic White [76.1%]) with cancer diagnosed at younger than 20 years during 1987 to 2012 were included. Mortality was similar across all groups. Compared with non-Hispanic White survivors at less than 5 years after diagnosis, there were no greatly increased hazard ratios (HRs) for hospitalization. Among survivors at 5 or more years after diagnosis, hospitalization HRs were 1.7 (95% CI, 1.0-3.0) for American Indian and Alaska Native survivors and 1.5 (95% CI, 0.9-2.4) for Black survivors. Significantly increased HRs among Hispanic children were observed for infection-related (HR, 1.4; 95% CI, 1.2-1.6), endocrine-related (HR, 1.3; 95% CI, 1.1-1.6), hematologic-related (HR, 1.3; 95% CI, 1.1-1.5), respiratory-related (HR, 1.3; 95% CI, 1.0-1.5), and digestive-related (HR, 1.2; 95% CI, 1.0-1.5) conditions. American Indian and Alaskan Native children had increased HRs for infection-related (HR, 2.3; 95% CI, 1.2-4.5), hematologic-related (HR, 3.0; 95% CI, 1.4-6.5), and digestive-related (HR, 2.6; 95% CI, 1.3-5.4) conditions. Both American Indian and Alaska Native (HR, 3.6; 95% CI, 1.4-9.0) and Black (HR, 2.5; 95% CI, 1.2-5.5) children had increased mental health-related hospitalizations and death. Conclusions and Relevance: In this cohort study, disproportionately increased long-term risks of hospitalization for physical and mental conditions may have contributed to worse outcomes by race. A key component to bridging the morbidity gap by race is improved understanding of reasons for greater cause-specific hospitalizations in some groups, with development of culturally appropriate intervention strategies.

A Multi-Phase Transport model for nuclear collisions at RHIC

To study heavy ion collisions at energies available from the Relativistic Heavy Ion Collider, we have developed a multi-phase transport model that includes both initial partonic and final hadronic interactions. Specifically, the parton cascade model ZPC, which uses as input the parton distribution from the HIJING model, is extended to include the quark-gluon to hadronic matter transition and also final-state hadronic interactions based on the ART model. Predictions of the model for central Au on Au collisions at RHIC are reported.Comment: 7 pages, 4 figure

Timelike Single-logarithm-resummed Splitting Functions

We calculate the single logarithmic contributions to the quark singlet and gluon matrix of timelike splitting functions at all orders in the modified minimal-subtraction (MSbar) scheme. We fix two of the degrees of freedom of this matrix from the analogous results in the massive-gluon regularization scheme by using the relation between that scheme and the MSbar scheme. We determine this scheme transformation from the double logarithmic contributions to the timelike splitting functions and the coefficient functions of inclusive particle production in e+ e- annihilation now available in both schemes. The remaining two degrees of freedom are fixed by reasonable physical assumptions. The results agree with the fixed-order results at next-to-next-to-leading order in the literature.Comment: Minor changes to the text, accepted for publication in Nucl. Phys.

First order optical potentials and 25 to 40 MeV proton elastic scattering

The differential cross sections and analyzing powers from the elastic scattering of 25 and 40 MeV protons from many nuclei have been studied. Analyses have been made using a fully microscopic model of proton-nucleus scattering seeking to establish a means appropriate for use in analyses of radioactive beam scattering from hydrogen with ion energies 25A and 40A MeV.Comment: 9 pages, RevTeX, 4 figure

Proton-Antiproton Annihilation into a Lambda_c-Antilambda_c Pair

The process p-pbar -> Lambda_c-Antilambda_c is investigated within the handbag approach. It is shown that the dominant dynamical mechanism, characterized by the partonic subprocess u-ubar -> c-cbar factorizes in the sense that only the subprocess contains highly virtual partons, a gluon to lowest order of perturbative QCD, while the hadronic matrix elements embody only soft scales and can be parameterized in terms of helicity flip and non-flip generalized parton distributions. Modelling these parton distributions by overlaps of light-cone wave functions for the involved baryons we are able to predict cross sections and spin correlation parameters for the process of interest.Comment: 39 pages, 7 figures, problems with printout of figures resolved, Ref. 33 and referring sentences in section 4 change

Space-filling and benthic competition on coral reefs

Reef-building corals are ecosystem engineers that compete with other benthic organisms for space and resources. Corals harvest energy through their surface by photosynthesis and heterotrophic feeding, and they divert part of this energy to defend their outer colony perimeter against competitors. Here, we hypothesized that corals with a larger space-filling surface and smaller perimeters increase energy gain while reducing the exposure to competitors. This predicted an association between these two geometric properties of corals and the competitive outcome against other benthic organisms. To test the prediction, fifty coral colonies from the Caribbean island of Curaçao were rendered using digital 3D and 2D reconstructions. The surface areas, perimeters, box-counting dimensions (as a proxy of surface and perimeter space-filling), and other geometric properties were extracted and analyzed with respect to the percentage of the perimeter losing or winning against competitors based on the coral tissue apparent growth or damage. The increase in surface space-filling dimension was the only significant single indicator of coral winning outcomes, but the combination of surface space-filling dimension with perimeter length increased the statistical prediction of coral competition outcomes. Corals with larger surface space-filling dimensions (Ds > 2) and smaller perimeters displayed more winning outcomes, confirming the initial hypothesis. We propose that the space-filling property of coral surfaces complemented with other proxies of coral competitiveness, such as life history traits, will provide a more accurate quantitative characterization of coral competition outcomes on coral reefs. This framework also applies to other organisms or ecological systems that rely on complex surfaces to obtain energy for competition