Scalar Mesons as qbar^2 q^2? Insight from the Lattice

I describe some insight obtained from a lattice calculation on the possibility that the light scalar mesons are \qbar^2 q^2 states rather than \qbar q. First I review some general features of \qbar^2 q^2 states in QCD inspired quark models. Then I describe a lattice QCD calculation of pseudoscalar meson scattering amplitudes, ignoring quark loops and quark annihilation, which finds indications that for sufficiently heavy quarks there is a stable four-quark bound state with JPC=0{++} and non-exotic flavor quantum numbers.Comment: 13 pages, 4 images, uses aipproc.cl

Mean lifetimes of V-particles and heavy mesons

A maximum-likelihood procedure for determining mean lifetimes of V-particles from cloud-chamber data is applied to samples taken from a group of 134 neutral V-particle decays. For 74 events which were consistent with a decay into a proton and a negative π-meson, a lifetime of (2.5±0.7)×10-10 sec is obtained. Dividing the data into "low Q" and "high Q" groups on the basis of the calculated energy release in the decay, a value of τL=(2.9±0.8)×10-10 sec is found for those cases with 0<~Q<~50 Mev and a value of τH=(1.6±0.5)×10-10 sec is found for those cases with 50<Q<~150 Mev. While no significant difference exists between these two values, the difference is greater than for other plausible division schemes which are considered. A qualitative discussion of lifetimes is given for the case of 23 charged V-particle decays. For the charged V-particles these data suggest either a lifetime less than that of the neutral V-particles, provided the sample is homogeneous, or, more likely, an apparent average lifetime less than that of the neutral V-particles, if the sample is a mixture of two or more types of particles. The possibility that κ- and/or χ-mesons make up a part of these decays is considered

Anisotropic admixture in color-superconducting quark matter

The analysis of color-superconducting two-flavor deconfined quark matter at moderate densities is extended to include a particular spin-1 Cooper pairing of those quarks which do not participate in the standard spin-0 diquark condensate. (i) The relativistic spin-1 gap Delta' implies spontaneous breakdown of rotation invariance manifested in the form of the quasi-fermion dispersion law. (ii) The critical temperature of the anisotropic component is approximately given by the relation T_c'~ Delta'(T=0)/3. (iii) For massless fermions the gas of anisotropic Bogolyubov-Valatin quasiquarks becomes effectively gapless and two-dimensional. Consequently, its specific heat depends quadratically on temperature. (iv) All collective Nambu-Goldstone excitations of the anisotropic phase have a linear dispersion law and the whole system remains a superfluid. (v) The system exhibits an electromagnetic Meissner effect.Comment: v2: references added, angular dependence of the gap clarified, v3: extended discussion, typo in eq. (5) corrected, version accepted for publication in PR

Ion induced quark-gluon implosion

We investigate nuclear fragmentation in the central proton-nucleus and nucleus - nucleus collisions at the energies of LHC. We argue that within the semi-classical approximation because of fast increase with energy of cross sections of soft and hard interactions each nucleon is stripped in the average process off ``soft'' partons and fragments into a collection of leading quarks and gluons with large $p_t$. Valence quarks and gluons are streaming in the opposite directions when viewed in the c.m. of the produced system. The resulting pattern of the fragmentation of the colliding nuclei leads to an implosion of the quark and gluon constituents of the nuclei. The matter density produced at the initial stage in the nucleus fragmentation region is estimated to be $\geq$ 50 GeV/fm$^3$ at the LHC energies and probably $\geq$ 10 GeV/fm$^3$ at RHIC.Comment: 5 pages, final version, discussion of the signals of the new phase is expande

Spectrum analysis of strong motion earthquakes

The problem of the dynamic response of a structure to an earthquake has been formulated in a manner which permits separation of the characteristics of particular structures from the characteristics of the earthquake. The expression involving the characteristics of the earthquake is defined as the "spectrum" of the earthquake and it is shown that the spectrum is simply a plot of the response of a simple oscillator versus the period of the oscillator. Eighty-eight such spectra were computed by means of an electric analog computer and are presented in this report. It is found that damping is a very important parameter in the overall problem; relatively small amounts of damping reduce structural response sharply. It is shown that, when damping is considered, the spectra are consistent with the hypothesis of a distribution about a mean value. It is concluded that the concept of a "dominant ground period" is not valid for the purpose of aseismic structural design. Further research on damping in buildings is recommended, and it is proposed that the mean value of a damped spectrum be used as a quantitative measure of earthquake intensity

Twin Studies, Molecular Genetics, Politics, and Tolerance: A Response to Beckwith and Morris

Beckwith and Morris raise concerns about the value of twin studies for understanding the role of genetics in complex human behavior, but virtually all of their concerns have been raised and rebutted before. When it comes to the equal environments assumption (EEA), the best approach is to test for and control possible violations of the EEA on heritability estimates rather than merely rejecting all empirical evidence because of the possibility of EEA violations. In many respects, since the study of the genetic basis of complex human behaviors now includes many methods in addition to twin studies, Beckwith and Morris’s critique applies more to the behavioral genetics of a quarter century ago than to today’s multifaceted behavioral genetics. Twin studies establish that there is a sizeable genetic component to political orientations, thereby giving cause to look further at the nature of that role by using other methodologies, including molecular genetics.We conclude by pointing out that the normative implications of the relevance of genes to human behavior are not nearly as worrisome as Beckwith and Morris seem to believe

Isospin asymmetry and type-I superconductivity in neutron star matter

It has been argued by Buckley et. al.(Phys. Rev. Lett. 92, 151102, 2004) that nuclear matter is a type-I rather than a type-II superconductor. The suggested mechanism is a strong interaction between neutron and proton Cooper pairs, which arises from an assumed U(2) symmetry of the effective potential, which is supposed to originate in isospin symmetry of the underlying nuclear interactions. To test this claim, we perform an explicit mean-field calculation of the effective potential of the Cooper pairs in a model with a simple four-point pairing interaction. In the neutron star context, matter is very neutron rich with less than 10% protons, so there is no neutron-proton pairing. We find that under these conditions our model shows no interaction between proton Cooper pairs and neutron Cooper pairs at the mean-field level. We estimate the leading contribution beyond mean field and find that it is is small and attractive at weak coupling.Comment: 7 pages, 2 figure

Cooling of a Compact Star with a LOFF Matter Core

Specific heat and neutrino emissivity due to direct URCA processes for quark matter in the color superconductive Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phase of Quantum-Chromodynamics have been evaluated. The cooling rate of simplified models of compact stars with a LOFF matter core is estimated.Comment: 3 pages, 1 figure, to appear in the proceedings of the Helmoltz International Summer School of Theoretical Physics on Dense Matter in Heavy Ion Collisions and Astrophysics, JINR, Dubna, Russia, 21 Aug - 1 Sep 200

Do GAAP And IFRS Differ In Collectiblity Judgments Related To Revenue Recognition?

The goal of this study is to examine whether financial statement preparers may interpret the collectibility threshold differently given the differences in the prior definitions of “probable” in IFRS and GAAP. We conducted an experiment where participants were provided with either the IFRS or GAAP definition of “probable” and then asked to evaluate five short revenue recognition scenarios. We find that their judgments regarding collectibility of consideration did not differ across the IFRS or GAAP conditions. This study contributes to the prior accounting literature on interpreting vague verbal probability terms and expands this line of work to the arena of revenue recognition. Our results also provide insight for standard setter and policy makers in their efforts to achieve true convergence in accounting standards.

Meson Exchange Effect on Color Superconductivity

We investigate the effects of pion and gluon exchanges on the formation of two-flavor color superconductivity at moderate density, $\mu <1 GeV$. The chiral quark model proposed by Manohar and Georgi containing pions as well as gluons is employed to show that the pion exchange reduces substantially the value of the superconducting gap gotten with the gluon exchange only. It turns out that the pion exchanges produce a repulsion between quark-quark pair in a spin and isospin singlet state. We suggest that the phase consisiting of pions, gluons and quarks is one of the candidates of in-medium QCD phase at moderate density.Comment: 8 pages, 1 figure, minor correction