Transverse momentum distribution in Drell-Yan pair and W and Z boson production

We exhibit and discuss the QCD prediction for the transverse momentum distribution of W bosons, Z bosons and high-mass virtual photons produced in high-energy hadron-hadron collisions. Recent work has shown that this prediction is consistent with the structure of leading twist initial state interactions.

The expression we present is expected to give results correct up to order _s^N(Q) for any Q_T when the boson mass Q is very large (> 10⁸ GeV!), given only input from perturbative calculations at order _s^N+2 and deeply inelastic scattering structure functions. We specify the required N = 0 coefficients, employing the order _s² results of Kodaira and Trentadue and of Davies and Stirling. We then show how the expression should be modified to deal with current energy scales. We also discuss the connection between low-Q_T and high-Q_T formulae.     

Green function theory of chemisorption on sp-hybrid crystals

A self-consistent Green function calculation of the adatom charge transfer (Δq) and the chemisorption energy (ΔE) is performed for hydrogen and the halogens on Si and Ge substrates, which are modeled by sp-hybrid orbital chains. The effect of Shockley surface states on the hydrogen chemisorption process is studied in some detail. From the chemisorption point of view, the behaviour of Si resembles that of Ge, the (111) surfaces having a smaller value of |ΔE| than the (100) ones for all the adsorbates considered. In the case of the halogens, the strong reactivity of fluorine is confirmed by the large values obtained for Δq and |ΔF|.     

Study of the reactions 12C(d,d)12C and 12C(d,p)13C across the resonance at Ed = 2.71 MeV

The second order processes in particle transfer reactions are tested by measuring the resonance structure of the 3⁺ state of ¹⁴N at 12.61 MeV for some outgoing channels of the ¹²C + d reaction.     

Non-perturbative contribution to the thrust distribution in <Emphasis Type="Italic">e</Emphasis><Superscript>+</Superscript><Emphasis Type="Italic">e</Emphasis><Superscript>−</Superscript> annihilation

We re-evaluate the non-perturbative contribution to the thrust distribution in e ⁺ e ⁻→ hadrons, in the light of the latest experimental data and the recent NNLO perturbative calculation of this quantity. By extending the calculation to NNLO+NLL accuracy, we perform the most detailed study to date of the effects of non-perturbative physics on this observable. In particular, we investigate how well a model based on a low-scale QCD effective coupling can account for such effects. We find that the difference between the improved perturbative distribution and the experimental data is consistent with a 1/Q-dependent non-perturbative shift in the distribution, as predicted by the effective coupling model. Best fit values of α _s (91.2 GeV)=0.1164_−0.0026^+0.0028 and α ₀(2 GeV)=0.59±0.03 are obtained with χ ²/d.o.f.=1.09. This is consistent with NLO+NLL results but the quality of fit is improved. The agreement in α ₀ is non-trivial because a part of the 1/Q-dependent contribution (the infrared renormalon) is included in the NNLO perturbative correction. Address after 1 October 2008: Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, Oxford OX1 3NP, UK.     

(±)‐7‐Oxo‐1,2,3,4,4a,5,6,7‐octa­hydro­naphthalene‐1‐acetic acid: catemeric hydrogen bonding and diastereomeric disorder in a bicyclic unsaturated ɛ‐keto acid

The 68.5:31.5 mixture of diastereoisomers obtained in the synthesis of the title compound, C₁₂H₁₆O₃, yielded sharply melting crystals containing the same ratio of epimers, in a disordered crystallographic arrangement. The disorder resides almost entirely in the carboxy­methyl side chain, but places the two sets of carboxyl O atoms at nearly identical paired spatial positions. Neither component displays significant carboxyl disorder, and the mol­ecules aggregate as hydrogen‐bonded carboxyl‐to‐ketone catemers [O⋯O = 2.673 (4) Å and O—H⋯O = 158°] having glide‐related components, with centro­symmetrically related pairs of chains following axes perpendicular to b. Close intermolecular C—H⋯O contacts exist for both the ketone and the carboxyl group. The energetics of the epimers and of their crystallization mode are discussed.     

Forensic performance of Investigator DIPplex indels genotyping kit in native,immigrant, and admixed populations in South Africa

The utilization of binary markers in human individual identification is gaining ground in forensic genetics. We analyzed the polymorphisms from the first commercial indel kit Investigator DIPplex (Qiagen) in 512 individuals from Afrikaner, Indian, admixed Cape Colored, and the native Bantu Xhosa and Zulu origin in South Africa and evaluated forensic and population genetics parameters for their forensic application in South Africa. The levels of genetic diversity in population and forensic parameters in South Africa are similar to other published data, with lower diversity values for the native Bantu. Departures from Hardy–Weinberg expectations were observed in HLD97 in Indians, Admixed and Bantus, along with 6.83% null homozygotes in the Bantu populations. Sequencing of the flanking regions showed a previously reported transition G>A in rs17245568. Strong population structure was detected with Fst, AMOVA, and the Bayesian unsupervised clustering method in STRUCTURE. Therefore we evaluated the efficiency of individual assignments to population groups using the ancestral membership proportions from STRUCTURE and the Bayesian classification algorithm in Snipper App Suite. Both methods showed low cross‐assignment error (0–4%) between Bantus and either Afrikaners or Indians. The differentiation between populations seems to be driven by four loci under positive selection pressure. Based on these results, we draw recommendations for the application of this kit in SA.     

Deuterium incorporation into cellulose: a mini-review of biological and chemical methods

Cellulose - Isotopic enrichment offers structural insights that are not easily accessible with natural abundance isotopic composition. Deuterated cellulose has attracted considerable attention in...     

The synthesis of bis(fulvalene)dicobalt hexafluorophosphate [(h5:h5′-C10H8)2 CoIII2][PF6]2

The organometallic compounds (Ph₃P)AuC(OMe)=NAr and [(EtO)(ArN=)C]₂ Hg can act as monodentate or as balentate ligand, respectively, towards another, different emtal atom (e.g. Ag and Rh).