Is chiral symmetry restored in the excited meson spectrum?

The large degeneracy observed in the excited meson spectrum by the Cristal Barrel Collaboration in the experimental data on proton–antiproton annihilation in flight into mesons in the range 1.9–2.4 GeV has been interpreted as a signal of chiral symmetry restoration. In this work we suggest that such degeneracy may be an indication of the confinement potential modification by color screening. The experimental data can be fairly well reproduced in a constituent quark model with a screened linear confinement potential without changing the dynamical quark mass. Observables that could discriminate our model from those which explicitly restore the chiral symmetry are proposed.     

Is plate tectonics a case of non-extensive thermodynamics?

Bird (2003) [5] proposed that the distribution of areas of the tectonic plates follows a power law and that this distribution fitted well with the concepts of a few major plates and a hierarchical self-similar organization of blocks at the boundary scale, a fractal plate distribution and a self-organized system. Here we apply the concepts of non-extensive statistical mechanics (NESM) to plate tectonics. The application of NESM is appropriate to systems such as tectonic plates where non-linearity, long-range interactions, memory effects and scaling are important. We calculate the probability density function for the areas of the tectonic plates. Our results show that three classes (small, intermediate and large) of tectonic plates can be distinguished, which is consistent with the observations of Bird. Furthermore, taking into account that for the intermediate class of tectonic plates the cumulative frequency distribution behaves as a power law with exponent 1/3, we estimate a thermodynamic q parameter of q=1.75, which supports the conclusion that the plate tectonics system is a sub-extensive one.     

Is BTZ a separate superselection sector of CTMG?

We exhibit exact solutions of (positive) matter coupled to original “wrong G-sign” cosmological TMG. They all evolve to conical singularity, rather than to black hole – here negative mass – BTZ. This provides evidence that the latter constitute a separate “superselection” sector, one that unlike in GR, is not reachable by physical sources.     

Is Galaxy Dark Matter a Property of Spacetime?

We describe the motion of a particle in acentral field in an expanding universe. Use is made ofa double expansion in 1/c and 1/, where c and are the speed of light and the Hubble time. In thelowest approximation the rotational velocity is shownto satisfy v⁴ = 2/3 GMcH₀, whereG is Newton's gravitational constant, M is the mass ofthe central body (galaxy), and H₀ is theHubble constant. This formula satisfies observations of stars moving inspiral and elliptical galaxies, and is in accordancewith the familiar Tully–Fisher law.     

Is the Luttinger Liquid a New State of Matter?

We are demonstrating that the Luttinger model with short range interaction can be treated as a type of Fermi liquid. In line with the main dogma of Landau’s theory one can define a fermion excitation renormalized by interaction and show that in terms of these fermions any excited state of the system is described by free particles. The fermions are a mixture of renormalized right and left electrons. The electric charge and chirality of the Landau quasi-particle is discussed.     

Is a classical description of stable non-BPS D-branes possible?

We study the classical geometry produced by a stack of stable (i.e., tachyon-free) non-BPS D-branes present in K3 compactifications of type II string theory. This classical representation is derived by solving the equations of motion describing the low-energy dynamics of the supergravity fields which couple to the non-BPS state. Differently from what expected, this configuration displays a singular behaviour: the space–time geometry has a repulson-like singularity. This fact suggests that the simplest setting, namely a set of coinciding non-interacting D-branes, is not acceptable. We finally discuss the possible existence of other acceptable configurations corresponding to more complicated bound states of these non-BPS branes.     

Is Human Papillomavirus a Causative Factor of Glottic Cancer?

Objectives

Human papillomavirus (HPV) infection is controversial as a causative factor of head and neck cancers despite the relatively high frequency of HPV infection in extragenital organ cancers. We aimed to clarify whether HPV directly affects the oncogenesis and biologic behavior of glottis cancer (GC).

Methods

Paraffin block was obtained from 95 patients who were diagnosed as GC and 15 normal controls. HPV genotyping chip, real-time polymerase chain reaction (PCR) was used for identification of prevalence, phenotype, and physical status of HPV. We compared results with the clinicopathological parameters of GC patients.

Results

HPV was detected in 7.4% (7 of 95) of GC patients, whereas 0% (0 of 15) of controls. Of the HPV-positive tumors in GCs, HPV-16 was the single most common type and HPV-16 prevalence rate was 57.1% (4 of 7). Among the HPV-16 infected GCs, integration of HPV-16 was found only in one case (1 of 4). There was no significant difference in HPV prevalence between GC and controls and HPV had no significant relation with any clinicopathologic parameters of GC patients.

Conclusion

HPV infection may not be a causative factor in the oncogenesis and biologic behavior of GC.     

What Is the State of a Hydrogen Atom Leaving a Stern-Gerlach Interferometer?

We discuss experimental results on Stern-Gerlachinterferometry with atoms. After a theoretical approachsuited for fast atoms, we discuss elementary experimentson the preservation of atomic coherence. Then we examine the action of theinterferometer as producing atoms with new properties,beaded atoms, and their radiative properties.     

Hyper-Kähler metrics and a generalization of the Bogomolny equations

We generalize the Bogomolny equations to field equations on ^{3 n} and describe a twistor correspondence. We consider a general hyper-Kähler metric in dimension 4n with an action of the torusT ⁿ compatible with the hyper-Kähler structure. We prove that such a metric can be described in terms of theT ⁿ -solution of the field equations coming from the twistor space of the metric.     

Is there an experimental verification of a negative index of refraction yet?

We show that recent claims of experimental verification of a negative index of refraction in metallic metamaterials, "left-handed" microwave frequencies, are questionable. At these frequencies the imaginary part of the dielectric permittivity is significant or even dominates its real part, and hence the effective medium behaves as a metal, i.e., with losses below the cutoff frequency of relevance. Then, the refractive index is complex, and there is not a distinction between right- and left-handed material because the electromagnetic wave is inhomogeneous. Just by using this idea we explain the transmittivities that were recently obtained in experiments by Shelby et al. [Science 292, 77 (2001) and Appl. Phys. Lett. 78, 489 (2001)].     

Is theS-meson a baryonium state?

If theS-meson is assumed to be a baryonium state composed of an isospin one diquark and antidiquark, it will be produced in \(\bar pp\) reactions as a mixture ofI=0 andI=1 baryonium states. The experimentally observed large ratio of the cross sections of the reactions \(\bar pp \to S \to \bar pp\) and \(\bar pp \to S^0 \to \bar nn\) is then explained on basis of quark additivity and conservation of isospin in thes-channel. The model predicts: \(\sigma (\bar pp \to S^0 \to \bar pp):\sigma (\bar pp \to S^0 \to \bar nn):\sigma (\bar pn \to S^ - \to \bar pn) = 25:1:16\) .     

Is There a Hierarchy of the Hadron Low pT Spectra?

A compilation of fits to the low p_T hadron distributions is presented. The universality of the distributions is examined. The p_T distributians of direct pions and resonances in the reaction p p → 2π+2π−π⁰ at 5.7 GeV/c are fitted separately. Indications are found that up to ISR energies there are three types oflow p_T inclusive hadron distributions in hadron-hadron interactions. The inclusive p_T distributions of different particles are divided into these three groups according to the particle mass.     

Is the Free Electromagnetic Field a Consequence of Maxwell's Equations or a Postulate?

It is generally accepted that solutions of so called free Maxwell equations for = 0 (null charge density at every point of the whole space) describe a free electromagnetic field for which flux lines neither begin nor end in a charge). In order to avoid ambiguities and unacceptable approximation which have place in the conventional approach in respect to the free field concept, we explicitly consider three possible types of space regions: (i) isolated charge-free region, where a resultant electric field with the flux lines which either begin or end in a charge is zero in every point, for example, inside a hollow conductor of any shape or in a free-charge universe; (ii) non-isolated charge-free region, where this electric [see (i)] field is not zero in every point; and (iii) charge-neutral region, where point charges exist but their algebraic sum is zero. According to these definitions a strict mathematical interpretation of Maxwell's equations gives following conclusions: (1) In isolated charge-free regions electric free field cannot be unconditionally understood neither as a direct consequence of Maxwell's equations nor as a valid approximation: it may be introduced only as a postulate; nevertheless, this case is compatible is the existence of a time-independent background magnetic field. (2) In both charge-neutral and non-isolated charge-free regions, where the condition = function or = 0 respectively holds, Maxwell's equation for the total electric field have non-zero solutions, as in the conventional approach. However, these solution cannot be strictly identified with the electric free field. This analysis gives rise to the reconsideration of the free-electromagnetic field concept and leads to the simplest implications in respect to charge-neutral universe.     

Is constituent quark scaling a unique sign of parton recombination?

We study the transverse momentum dependence of the anisotropic flow v₂ for π, K, nucleon, Λ, Ξ and Ω for Au+Au collisions at within two independent string-hadron transport approaches (RQMD and UrQMD). Although both models reach only 60% of the absolute magnitude of the measured v₂, they both predict the particle-type dependence of v₂ as observed by the RHIC experiments: v₂ exhibits a hadron-mass hierarchy in the low p_T region and a number-of-constituent-quark (NCQ) dependence in the intermediate p_T region. The failure of the hadronic models to reproduce the absolute magnitude of the observed v₂ indicates that transport calculations of heavy-ion collisions at RHIC must incorporate interactions among quarks and gluons in the early, hot and dense phase. The presence of an NCQ scaling in the string-hadron model results suggests that the particle-type dependences observed in heavy-ion collisions at intermediate p_T might be related to the hadronic cross sections in vacuum rather than to the hadronization process itself.