Heat of Combustion of the Product Formed by the Reaction of Diborane with 1,3-Butadiene

The net heat of combustion of the product formed by the reaction of diborane with 1,3-butadiene was found to be 18,700+/-150 Btu per pound for the reaction of liquid fuel to gaseous carbon dioxide, gaseous water, and solid boric oxide. The measurements were made in a Parr oxygen-bomb calorimeter, and the combustion was believed to be 98 percent complete. The estimated net heat of combustion for complete combustion would therefore be 19,075+/-150 Btu per pound. Since this value is approximately the same as the heat of combustion of butadiene, it seems certain that the material is partially oxidized

Higher-Twist Dynamics in Large Transverse Momentum Hadron Production

A scaling law analysis of the world data on inclusive large-pT hadron production in hadronic collisions is carried out. A significant deviation from leading-twist perturbative QCD predictions at next-to-leading order is reported. The observed discrepancy is largest at high values of xT=2pT/sqrt(s). In contrast, the production of prompt photons and jets exhibits the scaling behavior which is close to the conformal limit, in agreement with the leading-twist expectation. These results bring evidence for a non-negligible contribution of higher-twist processes in large-pT hadron production in hadronic collisions, where the hadron is produced directly in the hard subprocess rather than by gluon or quark jet fragmentation. Predictions for scaling exponents at RHIC and LHC are given, and it is suggested to trigger the isolated large-pT hadron production to enhance higher-twist processes.Comment: 5 pages, 4 figures. Extended introduction, additional reference

Dynamic versus Static Hadronic Structure Functions

"Static" structure functions are the probabilistic distributions computed from the square of the light-front wavefunctions of the target hadron. In contrast, the "dynamic" structure functions measured in deep inelastic lepton-hadron scattering include the effects of rescattering associated with the Wilson line. Initial- and final-state rescattering, neglected in the parton model, can have a profound effect in QCD hard-scattering reactions, producing single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, the breakdown of the Lam-Tung relation in Drell-Yan reactions, nuclear shadowing, and non-universal nuclear antishadowing--novel leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also review how "direct" higher-twist processes -- where a proton is produced in the hard subprocess itself -- can explain the anomalous proton-to-pion ratio seen in high centrality heavy ion collisions.Comment: Invited talk presented at the International Conference on Particles and Nuclei (PANIC08), Eilat, Israel, November 9-14, 200

The Baryon Anomaly: Evidence for Color Transparency and Direct Hadron Production at RHIC

We show that the QCD color transparency of higher-twist contributions to inclusive hadroproduction cross sections, where baryons are produced directly in a short-distance subprocess, can explain several remarkable features of high-$p_T$ baryon production in heavy ion collisions which have recently been observed at RHIC: (a) the anomalous increase of the proton-to-pion ratio with centrality (b): the increased power-law fall-off at fixed $x_T=2p_T/ \sqrt s$ of the charged particle production cross section in high centrality nuclear collisions, and (c): the anomalous decrease of the number of same-side hadrons produced in association with a proton trigger as the centrality increases. We show that correlations between opposite-side hyperons and kaons can provide a clear signature of higher-twist contributions. These phenomena emphasize the importance of understanding hadronization at the amplitude level in QCD illustrate how heavy ion collisions can provide sensitive tools for interpreting and testing fundamental properties of QCD.Comment: submitted to Physics Letters

Thermodynamic Basis for the Emergence of Genomes during Prebiotic Evolution

The RNA world hypothesis views modern organisms as descendants of RNA molecules. The earliest RNA molecules must have been random sequences, from which the first genomes that coded for polymerase ribozymes emerged. The quasispecies theory by Eigen predicts the existence of an error threshold limiting genomic stability during such transitions, but does not address the spontaneity of changes. Following a recent theoretical approach, we applied the quasispecies theory combined with kinetic/thermodynamic descriptions of RNA replication to analyze the collective behavior of RNA replicators based on known experimental kinetics data. We find that, with increasing fidelity (relative rate of base-extension for Watson-Crick versus mismatched base pairs), replications without enzymes, with ribozymes, and with protein-based polymerases are above, near, and below a critical point, respectively. The prebiotic evolution therefore must have crossed this critical region. Over large regions of the phase diagram, fitness increases with increasing fidelity, biasing random drifts in sequence space toward ‘crystallization.’ This region encloses the experimental nonenzymatic fidelity value, favoring evolutions toward polymerase sequences with ever higher fidelity, despite error rates above the error catastrophe threshold. Our work shows that experimentally characterized kinetics and thermodynamics of RNA replication allow us to determine the physicochemical conditions required for the spontaneous crystallization of biological information. Our findings also suggest that among many potential oligomers capable of templated replication, RNAs may have evolved to form prebiotic genomes due to the value of their nonenzymatic fidelity