Quantum Chromodynamics and the Pomeron

This volume describes the Pomeron, an object of crucial importance in very high energy particle physics. Starting with a general description of the Pomeron within the framework of Regge theory, the emergence of the Pomeron within scalar field theory is discussed, providing a natural foundation on which to develop the more realistic case of QCD. The reggeization of the gluon is demonstrated and used to build the Pomeron of perturbative QCD. The dynamical nature of the Pomeron and its role in small-x deep inelastic scattering and in diffractive scattering is also examined in detail. The volume concludes with a study of the colour dipole approach to high energy scattering and the explicit role of unitarity corrections. This book will be of interest to theoretical and experimental particle physicists, and applied mathematicians. First published in 1997, this title has been reissued as an Open Access publication

The Effect of Higher Order Corrections to the BFKL Equation on the Perturbative Pomeron

We discuss the significance of the next-to-leading order term in the BFKL equation on the energy dependence of diffractive processes controlled by the perturbative QCD pomeron. It is shown that whereas the large negative corrections do indeed reduce the rate of growth of diffractive amplitudes with increasing energy, this reduction is considerably less than previously expected.Comment: 6 pages, LATEX, 4 figure

Rapidity veto effects in the NLO BFKL equation

We examine the effect of suppressing the emission of gluons which are close by in rapidity in the BFKL framework. We show that, after removing the unphysical collinear logarithms which typically arise in formally higher orders of the perturbative expansion, the effect of the rapidity veto is greatly reduced. This is an important result, since it supports the use of multi-Regge and quasi-multi-Regge kinematics which are implemented in the leading and next-to-leading order BFKL formalism.Comment: 13 pages, 10 figures, submitted to Physics Letters

Solving the BFKL Equation with Running Coupling

We describe a formalism for solving the BFKL equation with a coupling that runs for momenta above a certain infrared cutoff. By suitably choosing matching conditions proper account is taken of the fact that the BFKL diffusion implies that the solution in the infrared (fixed coupling) regime depends upon the solution in the ultraviolet (running coupling) regime and vice versa. Expanding the BFKL kernel to a given order in the ratio of the transverse momenta allows arbitrary accuracy to be achieved.Comment: 11 pages, 2 fig

Organochlorines in common dolphins caught in shark nets during the Natal ‘sardine run’

The concentrations of organochlorines were determined in blubber and liver samples from common dolphins inhabiting the coastal waters of the south-east coast of southern Africa. Liver levels of PCBs and DDTs are far lower and do not appear directly associated with those in blubber. In males, blubber residue concentrations increased with age but in females a marked rapid decline in concentrations of PCBs and t-DDT was evident between the eighth and eleventh growth layer groups, approximately the age of sexual maturity and subsequent to their first or second ovulation. Lower levels in females are explained through transfer to the new-born calf during lactation and the consequences of this for the newborn calf are discussed

The Sexual health of pupils in years 4 to 6 of primary schools in rural Tanzania

Background/objectives: There is an urgent need for effective interventions to improve the sexual and\ud reproductive health of adolescents. Reliable data on the sexual health of adolescents are needed to guide\ud the development of such interventions. The aim was to describe the sexual health of pupils in years 4 to 6 of\ud 121 rural primary schools in north western Tanzania, before the implementation of an innovative sexual\ud health intervention in 58 of the schools.\ud Methods: A cross sectional survey of primary school pupils in rural Tanzania was carried out. The study\ud population comprised pupils registered in years 4 to 6 of 121 primary schools in 20 rural communities in\ud 1998. Basic demographic information was collected from all pupils seen. Those born before 1 January\ud 1985 (aged approximately 14 years and over) were invited to participate in the survey, and asked about\ud their knowledge and attitudes towards sexual health issues, and their sexual experience. A urine specimen\ud was requested and tested for HIV, Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG) and, for\ud females, pregnancy.\ud Results: 9283 pupils born before 1 January 1985 were enrolled and provided demographic information\ud and a urine sample. Male pupils were significantly older than females (mean age 15.5 years v 14.8 years,\ud p,0.001), but all other demographic characteristics were similar between the sexes. 14 (0.2%) of the\ud enrolled pupils (four male and 10 female) were HIV positive, 83 (0.9%) were positive for CT, and 12\ud (0.1%) for NG. 32 female pupils (0.8%) were positive by pregnancy test. Sexual experience was reported\ud by one fifth of primary school girls, and by almost half of boys. Only 45/114 (39%) girls with biological\ud markers of sexual activity reported having had sex.\ud Conclusions: HIV, CT, NG, and pregnancy were present though at relatively low levels among pupils in\ud years 4 to 6 of primary school. A high proportion of pupils with a biological marker of sexual activity\ud denied ever having had sex. Alternative ways of collecting sensitive data about the sexual behaviour of\ud school pupils should be explored

Balancing for Intestinal Nitrogen Indigestibility in High Producing Lactating Cattle: One Step Closer to Feeding a Cow Like a Pig?

This information was presented at the 2014 Cornell Nutrition Conference for Feed Manufacturers, organized by the Department of Animal Science In the College of Agriculture and Life Sciences at Cornell University. Softcover copies of the entire conference proceedings may be purchased at http://ansci.cals.cornell.edu/extension-outreach/adult-extension/dairy-management/order-proceedings-resources or by calling (607)255-4285

Soft lepton-flavor violation in a multi-Higgs-doublet seesaw model

We consider the Standard Model with an arbitrary number n_H of Higgs doublets and enlarge the lepton sector by adding to each lepton family \ell a right-handed neutrino singlet \nu_{\ell R}. We assume that all Yukawa-coupling matrices are diagonal, but the Majorana mass matrix M_R of the right-handed neutrino singlets is an arbitrary symmetric matrix, thereby introducing an explicit but soft violation of all lepton numbers. We investigate lepton-flavor-violating processes within this model. We pay particular attention to the large-m_R behavior of the amplitudes for these processes, where m_R is the order of magnitude of the matrix elements of M_R. While the amplitudes for processes like tau^- --> mu^- gamma and Z --> tau^+ mu^- drop as 1/m_R^2 for arbitrary n_H, processes like tau^- --> mu^- e^+ e^- and mu^- --> e^- e^+ e^- obey this power law only for n_H = 1. For n_H \geq 2, on the contrary, those amplitudes do not fall off when m_R increases, rather they converge towards constants. This non-decoupling of the right-handed scale occurs because of the sub-process ell^- --> ell'^- {S_b^0}^*, where S_b^0 is a neutral scalar which subsequently decays to e^+ e^-. That sub-process has a contribution from charged-scalar exchange which, for n_H \geq 2, does not decrease when m_R tends to infinity. We also perform a general study of the non-decoupling and argue that, after performing the limit m_R --> \infty and removing the \nu_R from the Lagrangian, our model becomes a multi-Higgs-doublet Standard Model with suppressed flavor-changing Yukawa couplings. Finally, we show that, with the usual assumptions about the mass scales in the seesaw mechanism, the branching ratios of all lepton-flavor-changing processes are several orders of magnitude smaller than present experimental limits.Comment: 46 pages, 2 figures, Revte

Domain wall mobility in nanowires: transverse versus vortex walls

The motion of domain walls in ferromagnetic, cylindrical nanowires is investigated numerically by solving the Landau-Lifshitz-Gilbert equation for a classical spin model in which energy contributions from exchange, crystalline anisotropy, dipole-dipole interaction, and a driving magnetic field are considered. Depending on the diameter, either transverse domain walls or vortex walls are found. The transverse domain wall is observed for diameters smaller than the exchange length of the given material. Here, the system behaves effectively one-dimensional and the domain wall mobility agrees with a result derived for a one-dimensional wall by Slonczewski. For low damping the domain wall mobility decreases with decreasing damping constant. With increasing diameter, a crossover to a vortex wall sets in which enhances the domain wall mobility drastically. For a vortex wall the domain wall mobility is described by the Walker-formula, with a domain wall width depending on the diameter of the wire. The main difference is the dependence on damping: for a vortex wall the domain wall mobility can be drastically increased for small values of the damping constant up to a factor of $1/\alpha^2$.Comment: 5 pages, 6 figure

The influence of the frontal surface area and swim velocity variation in front crawl active drag

Purpose The aims of this study were to 1) compare active drag (D-a) calculation between a single land-based measurement of frontal surface area (FSA) and in-water FSA measures obtained at key events of the arm pull (1, right upper-limb catch; 2, right upper-limb insweep; 3, right upper-limb exit and left upper-limb catch; 4, left upper-limb insweep; and 5, left upper-limb exit and right upper-limb catch) at front crawl swimming, and 2) compare mechanical power variables computed based on these two approaches. Methods Seventeen swimmers (11, male; 6, female; 16.15 +/- 0.94 yr old) were recruited. The FSA was measured based on two approaches: (i) nonvariation, that is, assuming a constant value, and (ii) variation, that is, calculated in each key event of the front crawl swim. Active drag based on a nonvariation of the FSA was measured using the Velocity Perturbation method. Active drag based on a variation approach was measured in each key event of the front crawl according to the law of linear motion. Pairedt-test (P <= 0.05), simple linear regression models, and Bland-Altman plots between assessment methods (variation vs nonvariation) were computed. Results The FSA (variation) was higher than when assuming a nonvariation (0.1110 +/- 0.010 vs 0.0968 +/- 0.010 m(2), Delta = 15.69%,t= 4.40,P< 0.001,d= 0.95). Active drag (variation) was also significantly higher than when assuming a nonvariation (88.44 +/- 25.92 vs 75.41 +/- 15.11 N, Delta = 16.09%,t= 3.66,P= 0.002,d= 0.61). Conclusions Besides the FSA, swim velocity also changes during the front crawl arm pull. The variation of both variables had a significant effect on the active drag measurement and consequently on mechanical power and total power input variables.This work is supported by national funds (FCT-Portuguese Foundation for Science and Technology) under the project UIDB/04045/2020. There were no conflicts of interests. The results of this study do not constitute endorsement by the American College of Sports Medicine. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation.info:eu-repo/semantics/publishedVersio