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 a Griffiths phase a prerequisite for colossal magnetoresistance?

Detailed measurements of the magnetic and transport behavior of the two La(1-x)Ca(x)MnO(3) single crystals exhibiting colossal magnetoresistance are summarized. The x=0.21 sample exhibits unusual exponents (delta = 20+/-1, gamma = 1.71+/-0.1, beta = 0.09+/-0.01, T(C) = 182+/-1 K) and, more importantly, a Griffiths phase characterized by an exponent lambda = 0.70+/-0.2. By contrast, the x=0.20 specimen displays Heisenberg model behavior with no evidence of such a phase. Thus while a Griffiths phase accounts for the behavior of La(1-x)Ca(x)MnO(3) near optimal doping, it does not appear to be a prerequisite for colossal magnetoresistance in this system.     

Is there a Di-Ω State?

Resonating-group method has been applied to calculate the ΩΩ (SIJ = -6,0,0) dibaryon state in theframework of the extended quark-delocalization color-screening model. The mass of the di-Ω is predicted to be about45 MeV lower than the Ω-Ω threshold. The effect of channel coupling due to the tensor force and sensitivity to mesonexchange short-range cutoff radius, ro have also been studied.     

Is turbulent mixing a self-convolution process?

Experimental results for the evolution of the probability distribution function (PDF) of a scalar mixed by a turbulent flow in a channel are presented. The sequence of PDF from an initial skewed distribution to a sharp Gaussian is found to be nonuniversal. The route toward homogeneization depends on the ratio between the cross sections of the dye injector and the channel. In connection with this observation, advantages, shortcomings, and applicability of models for the PDF evolution based on a self-convolution mechanism are discussed.     

Is There Really a Spin Crisis?

The matrix element of quark axial vector current is shown to be different from the nonrelativistic quark spin sum for a nucleon at rest. The nucleon spin content discovered in polarized deep inelastic scattering is shown to be accommodated in a constituent quark model with 15% sea quark component mixing. The relativistic correction and sea quark pair excitation inherently related to quark axial vector current reduce the nucleon axial charge and this reduction is compensated by the relativistic quark orbital angular momentum exactly and in turn keeps the nucleon spin 1/2 untouched. Nucleon tensor charge has similar but smaller relativistic and sea quark pair excitation reduction.     

Is there a Di-Ω State?

Resonating-group method has been applied to calculate the ΩΩ (SIJ=-6,0,0) dibaryon state in the framework of the extended quark-delocalization color-screening model. The mass of the di-Ω is predicted to be about 45 MeV lower than the Ω-Ω threshold. The effect of channel coupling due to the tensor force and sensitivity to meson exchange short-range cutoff radius, r₀ have also been studied.     

How Is a Protein Molecule Nearsighted？

The effect range of a local change of a protein molecule is calculated using a cluster method developed in this work based on the Gaussian software. This range is found to be about 8A°, which gives a concrete estimation on the “nearsightedness” by Kohn for protein molecules. The cluster method can be applied to calculation of the electronic density of a large molecule such as a motor protein and can provide a basis for the dynamical analysis of a single protein molecule.     

Is the collapse a phase transition?

It is shown that the process of the collapse during quantum measurements is a consequence of the quantum symmetry built in the formalism: there exists a nontrivial group of symmetry under which all possible states are invariant after the measurement of the given observable. On the basis of this fact, the postulate of collapse is derived with purely group theoretical considerations. These are analogous to the ones used in Landau's problem of phase transitions. Some further analogies of the processes of the collapse and the phase transitions are discussed.     

Is the nucleon a bound state?

In this paper we deal with the question of whether or not the nucleon is a bound state. It is shown that previous work on this problem is not conclusive. We find, however, a simple criterion which allows for an experimental decision of this question. For the nucleon to be a bound state, thep _1/2,1/2 phase has to have a negative sign at the inelastic threshold. A positive phase excludes the bound state picture but allows ap _1/2,1/2 resonance to occur.     

Is d* a candidate for a hexaquark-dominated exotic state?

We confirm our previous prediction of a d* state with I(JP) = 0(3+) [Phys. Rev. C 60, 045203(1999)] and report for the first time based on a microscopic calculation that d* has about 2/3 hidden color(CC)configurations and thus is a hexaquark-dominated exotic state. By performing a more elaborate dynamical coupledchannels investigation of the △△-CC system within the framework of the resonating group method(RGM) in a chiral quark model, we find that the d* state has a mass of about 2.38–2.42 Ge V, a root-mean-square radius(RMS) of0.76–0.88 fm, and a CC fraction of 66%–68%. The last may cause a rather narrow width for the d* which, together with the quantum numbers and our calculated mass, is consistent with the newly observed resonance-like structure(M ≈2380 Me V, Γ≈70 Me V) in double-pionic fusion reactions reported by the WASA-at-COSY Collaboration.     

Is a wind turbine a point source? (L)

Measurements show that practically all noise of wind turbine noise is produced by turbine blades, sometimes a few tens of meters long, despite that the model of a point source located at the hub height is commonly used. The plane of rotating blades is the critical location of the receiver because the distances to the blades are the shortest. It is shown that such location requires certain condition to be met. The model is valid far away from the wind turbine as well.     

Is there a c-theorem in four dimensions?

The difficulties of extending Zamolodchikov's c-theorem to dimensions d ≠ 2 are discussed. It is shown that, for d even, the one-point function of the trace of the stress tensor on the sphere, S^d, when suitably regularized, defines a c-function, which, at least to one loop order, is decreasing along RG trajectories and is stationary at RG fixed points, where it is proportional to the usual conformal anomaly. It is shown that the existence of such a c-function, if it satisfies these properties to all orders, is consistent with the expected behavior of QCD in four dimensions.     

Is there contextuality for a single qubit?

Cabello and Nakamura have shown [A. Cabello, Phys. Rev. Lett. 90, 190401 (2003)10.1103/PhysRevLett.90.190401] that the Kochen-Specker theorem can be applied to two-dimensional systems if one uses positive operator-valued measures (POVM). We show that the contextuality in their models is not of the Kochen-Specker type, but it is rather a result of not keeping track of the whole system on which the measurement is performed. This is connected to the fact that there is no one-to-one correspondence between the POVM elements and projectors on the extended Hilbert space, and the same POVM element has to originate from two different projectors when used in Cabello-Nakamura models. Moreover, we propose a hidden-variable formulation of the above models.