The OU goes digital

Describes how the Open University is embedding electronic library resources and services into e-learning

Ultrarelativistic nucleus-nucleus collisions and the quark-gluon plasma

We present an overview of selected aspects of ultrarelativistic nucleus-nucleus collisions, a research program devoted to the study of strongly interacting matter at high energy densities and in particular to the characterization of the quark-gluon plasma (QGP). The basic features of the phase diagram of nuclear matter, as currently understood theoretically, are discussed. The experimental program, carried out over a broad energy domain at various accelerators, is briefly reviewed, with an emphasis on the global characterization of nucleus-nucleus collisions. Two particular aspects are treated in more detail: i) the application of statistical models to a phenomenological description of particle production and the information it provides on the phase diagram; ii) the production of hadrons carrying charm quarks as messengers from the QGP phase.Comment: Based on lectures given by P.Braun-Munzinger at the VIII Hispalensis International Summer School, Oromana (Seville, Spain), June 9-21, 2003 32 pages, 20 figures. A clickable list of references available at http://www-linux.gsi.de/~andronic/qgp/qgp.htm

Summing Radiative Corrections to the Effective Potential

When one uses the Coleman-Weinberg renormalization condition, the effective potential $V$ in the massless $\phi_4^4$ theory with O(N) symmetry is completely determined by the renormalization group functions. It has been shown how the $(p+1)$ order renormalization group function determine the sum of all the N^{\mbox{\scriptsize p}}LL order contribution to $V$ to all orders in the loop expansion. We discuss here how, in addition to fixing the N^{\mbox{\scriptsize p}}LL contribution to $V$, the $(p+1)$ order renormalization group functions also can be used to determine portions of the N^{\mbox{\scriptsize p+n}}LL contributions to $V$. When these contributions are summed to all orders, the singularity structure of \mcv is altered. An alternate rearrangement of the contributions to $V$ in powers of $\ln \phi$, when the extremum condition $V^\prime (\phi = v) = 0$ is combined with the renormalization group equation, show that either $v = 0$ or $V$ is independent of $\phi$. This conclusion is supported by showing the LL, $\cdots$, N$^4$LL contributions to $V$ become progressively less dependent on $\phi$.Comment: 16 pages; added 2 figures and 2 tables; references revise

Transport of a quantum degenerate heteronuclear Bose-Fermi mixture in a harmonic trap

We report on the transport of mixed quantum degenerate gases of bosonic 87Rb and fermionic 40K in a harmonic potential provided by a modified QUIC trap. The samples are transported over a distance of 6 mm to the geometric center of the anti-Helmholtz coils of the QUIC trap. This transport mechanism was implemented by a small modification of the QUIC trap and is free of losses and heating. It allows all experiments using QUIC traps to use the highly homogeneous magnetic fields that can be created in the center of a QUIC trap and improves the optical access to the atoms, e.g., for experiments with optical lattices. This mechanism may be cascaded to cover even larger distances for applications with quantum degenerate samples.Comment: 7 pages, 8 figure

High-contrast dark resonance on the D2 - line of 87Rb in a vapor cell with different directions of the pump - probe waves

We propose a novel method enabling to create a high-contrast dark resonance in the 87Rb vapor D2-line. The method is based on an optical pumping of atoms into the working states by a two-frequency, linearly-polarized laser radiation propagating perpendicularly to the probe field. This new scheme is compared to the traditional scheme involving the circularly-polarized probe beam only, and significant improvement of the dark resonance parameters is found. Qualitative considerations are confirmed by numerical calculations.Comment: 7 pages, 4 figure

A Method to Identify and Analyze Biological Programs through Automated Reasoning.

Predictive biology is elusive because rigorous, data-constrained, mechanistic models of complex biological systems are difficult to derive and validate. Current approaches tend to construct and examine static interaction network models, which are descriptively rich but often lack explanatory and predictive power, or dynamic models that can be simulated to reproduce known behavior. However, in such approaches implicit assumptions are introduced as typically only one mechanism is considered, and exhaustively investigating all scenarios is impractical using simulation. To address these limitations, we present a methodology based on automated formal reasoning, which permits the synthesis and analysis of the complete set of logical models consistent with experimental observations. We test hypotheses against all candidate models, and remove the need for simulation by characterizing and simultaneously analyzing all mechanistic explanations of observed behavior. Our methodology transforms knowledge of complex biological processes from sets of possible interactions and experimental observations to precise, predictive biological programs governing cell function

LAPACK-Based Software for Subspace Identification

op****

Color-octet scalar decays to a gluon and an electroweak gauge boson in the Manohar-Wise model

We evaluate the one loop amplitudes giving rise to couplings between a scalar color octet, a gluon, and an electroweak gauge boson. These one loop amplitudes could give rise to new physics signals in $\gamma$ jet, $Z$ jet and $W$ jet production at the LHC. Branching ratios for color octet scalar decay into these modes can reach the 10% ($\gamma$ jet), and a few percent ($Z$ jet) level for masses below 2$m_t$. In a narrow kinematic window, the charged scalar can decay to $W$ jet with a substantial branching fraction.Comment: 14 pages, 8 Figure