Properties of new unflavored mesons below 2.4 GeV

The global features of spectrum of highly excited light nonstrange mesons can be well understood within both chiral symmetry restoration scenario combined with the relation $M^2\sim J+n$ and within nonrelativistic description based on the relation $M^2\sim L+n$. The predictions of these two alternative classifications for missing states are different and only future experiments can distinguish between the two. We elaborate and compare systematically the predictions of both schemes, which may serve as a suggestion for future experiments devoted to the search for missing states.Comment: 5 pages, to appear in Phys. Rev. C XX, 005200 (2007

Theory of phonon-drag thermopower of extrinsic semiconducting single-wall carbon nanotubes and comparison with previous experimental data

A theoretical model for the calculation of the phonon-drag thermopower, $S^{g}$, in degenerately doped semiconducting single-wall carbon nanotubes (SWCNTs) is proposed. Detailed calculations of $S^{g}$ are performed as a function of temperature, tube radius and position of the Fermi level. We derive a simple analytical expression for $S^{g}$ that can be utilized to determine the free carrier density in doped nanotubes. At low temperatures $S^{g}$ shows an activated behavior characteristic of the one-dimensional (1D) character of carriers. Screening effects are taken into account and it is found that they dramatically reduce the magnitude of $S^{g}$. Our results are compared with previous published experimental data in bulk p-doped SWCNT materials. Excellent agreement is obtained in the temperature range 10-200 K for a consistent set of parameters. This is a striking result in view of the complexity of these systems.Comment: 21 pages, 6 figures. This version has been accepted for publication in Phys. Rev.

Implications of the Crystal Barrel data for meson-baryon symmetries

Making use of numerous resonances discovered by the Crystal Barrel Collaboration we discuss some possible relations between the baryon and meson spectra of resonances composed of the light non-strange quarks. Our goal is to indicate new features that should be reproduced by the realistic dynamical models describing the hadron spectrum in the sector of light quarks.Comment: Completely modified version; to appear in Mod. Phys. Lett.

Generating New Specific Rna Interaction Interfaces Using C-loops

New RNA interaction interfaces are reported for designing RNA modules for directional supramolecular self-assembly. The new interfaces are generated from existing ones by inserting C-loops between the interaction motifs that mediate supramolecular assembly. C-Loops are new modular motifs recently identified in crystal structures that increase the helical twist of RNA helices in which they are inserted and thus reduce the distance between pairs of loop or loop-receptor motifs from 11 to 9 base-stacking layers while maintaining correct orientation for binding to cognate interaction interfaces. Binding specificities of C-loop-containing molecules for cognate molecules that also have inserted C-loops were found to range up to 20-fold. Binding affinities for most C-loop-containing molecules were generally equal or higher than those for the parent molecules lacking C-loops

Specific Rna Self-assembly With Minimal Paranemic Motifs

The paranemic crossover (PX) is a motif for assembling two nucleic acid molecules using Watson-Crick (WC) basepairing without unfolding preformed secondary structure in the individual molecules. Once formed, the paranemic assembly motif comprises adjacent parallel double helices that crossover at every possible point over the length of the motif. The interaction is reversible as it does not require denaturation of basepairs internal to each interacting molecular unit. Paranemic assembly has been demonstrated for DNA but not for RNA and only for motifs with four or more crossover points and lengths of five or more helical half-turns. Here we report the design of RNA molecules that paranemically assemble with the minimum number of two crossovers spanning the major groove to form paranemic motifs with a length of three half turns (3HT). Dissociation constants (K-d\u27s) were measured for a series of molecules in which the number of basepairs; between the crossover points was varied from five to eight basepairs. The paranemic 3HT complex with six basepairs (3HT_6M) was found to be the most stable with K-d = 1 x 10(-8) M. The half-time for kinetic exchange of the 3HT_6M complex was determined to be similar to 100 min, from which we calculated association and dissociation rate constants k(a) = 5.11 x 10(3) M(-1)s(-1) and k(d) = 5.11 x 10(-5) s(-1). RNA paranemic assembly of 3HT and 5HT complexes is blocked by single-base substitutions that disrupt individual intermolecular Watson-Crick basepairs; and is restored by compensatory substitutions that,restore those basepairs. The 3HT motif appears suitable for specific, programmable, and reversible tecto-RNA self-assembly for constructing artificial RNA molecular machines

Parity doubling in particle physics

Parity doubling in excited hadrons is reviewed. Parity degeneracy in hadrons was first experimentally observed 40 years ago. Recently new experimental data on light mesons caused much excitement and renewed interest to the phenomenon, which still remains to be enigmatic. The present retrospective review is an attempt to trace the history of parity doubling phenomenon, thus providing a kind of introduction to the subject. We begin with early approaches of 1960s (Regge theory and dynamical symmetries) and end up with the latest trends (manifestations of broader degeneracies and AdS/QCD). We show the evolution of various ideas about parity doubling. The experimental evidence for this phenomenon is scrutinized in the non-strange sector. Some experiments of 1960s devoted to the search for missing non-strange bosons are re-examined and it is argued that results of these experiments are encouraging from the modern perspective.Comment: Version to appear in Int. J. Mod. Phys. A, 63 pages, 9 figure

Weinberg like sum rules revisited

The generalized Weinberg sum rules containing the difference of isovector vector and axial-vector spectral functions saturated by both finite and infinite number of narrow resonances are considered. We summarize the status of these sum rules and analyze their overall agreement with phenomenological Lagrangians, low-energy relations, parity doubling, hadron string models, and experimental data.Comment: 31 pages, noticed misprints are corrected, references are added, and other minor corrections are mad

Wigner function properties for electromagnetic systems

Using the Wigner-Vlasov formalism, an exact 3D solution of the Schr\"odinger equation for a scalar particle in an electromagnetic field is constructed. Electric and magnetic fields are non-uniform. According to the exact expression for the wave function, the search for two types of the Wigner functions is conducted. The first function is the usual Wigner function with a modified momentum. The second Wigner function is constructed on the basis of the Weyl-Stratonovich transform in papers [Phys. Rev. A 35 2791 (1987)] or [Phys. Rev. B 99 014423 (2019)]. It turns out that the second function, unlike the first one, has areas of negative values for wave functions with the Gaussian distribution (Hudson's theorem). On the one hand, knowing the Wigner functions allows one to find the distribution of the mean momentum vector field and the energy spectrum of the quantum system. On the other hand, within the framework of the Wigner-Vlasov formalism, the mean momentum distribution and the magnitude of the energy are initially known. Consequently, the mean momentum distributions and energy values obtained according to the Wigner functions can be compared with the exact momentum distribution and energy values. This paper presents this comparison and describes the differences. For the first Wigner function, an analog of the Moyal equation with an electromagnetic part and the Hamilton-Jacobi operator equation are obtained. An operator analogue of the {\guillemotleft}motion equation{\guillemotright} with electromagnetic interaction is constructed. For the second Vlasov equation, an operator expression for the Vlasov-Moyal approximation for systems with electromagnetic interaction is obtained.Comment: 26 pages, 2 figure

Engineering cooperative tecto–RNA complexes having programmable stoichiometries

High affinity and specificity RNA–RNA binding interfaces can be constructed by combining pairs of GNRA loop/loop–receptor interaction motifs. These interactions can be fused using flexible four-way junction motifs to create divalent, self-assembling scaffolding units (‘tecto-RNA’) that have favorable properties for nanomedicine and other applications. We describe the design and directed assembly of tecto-RNA units ranging from closed, cooperatively assembling ring-shaped complexes of programmable stoichiometries (dimers, trimers and tetramers) to open multimeric structures. The novelty of this work is that tuning of the stoichiometries of self-assembled complexes is achieved by precise positioning of the interaction motifs in the monomer units rather than changing their binding specificities. Structure-probing and transmission electron microscopy studies as well as thermodynamic analysis support formation of closed cooperative complexes that are highly resistant to nuclease digestion. The present designs provide two helical arms per RNA monomer for further functionalization aims