Baryon Antibaryon Nonets

The baryon-antibaryon SU(3) nonets are proposed as a scheme to classify the increased number of experimentally observed enhancements near the baryon antibaryon mass threshold. The scheme is similar to the Fermi-Yang-Sakata model, which was put forth about fifty years ago in explaining the mesons observed at that time. According to the present scheme, many new baryon-antibaryon bound states are predicted, and their possible productions in quarkonium decays and B decays are suggested for experimental search.Comment: 5 pages, 1 figur

The littlest Higgs model and Higgs boson associated production with top quark pair at high energy linear e+e−e^{+}e^{-} collider

In the parameter space allowed by the electroweak precision measurement data, we consider the contributions of the new particles predicted by the littlest Higgs($LH$) model to the Higgs boson associated production with top quark pair in the future high energy linear $e^{+}e^{-}$ collider($ILC$). We find that the contributions mainly come from the new gauge bosons $Z_{H}$ and $B_{H}$. For reasonable values of the free parameters, the absolute value of the relative correction parameter $\delta\sigma/\sigma^{SM}$ can be significanly large, which might be observed in the future $ILC$ experiment with $\sqrt{S}=800GeV$.Comment: latex files, 13 pages, 3 figure

Aberrant behaviours of reaction diffusion self-organisation models on growing domains in the presence of gene expression time delays

Turing’s pattern formation mechanism exhibits sensitivity to the details of the initial conditions suggesting that, in isolation, it cannot robustly generate pattern within noisy biological environments. Nonetheless, secondary aspects of developmental self-organisation, such as a growing domain, have been shown to ameliorate this aberrant model behaviour. Furthermore, while in-situ hybridisation reveals the presence of gene expression in developmental processes, the influence of such dynamics on Turing’s model has received limited attention. Here, we novelly focus on the Gierer–Meinhardt reaction diffusion system considering delays due the time taken for gene expression, while incorporating a number of different domain growth profiles to further explore the influence and interplay of domain growth and gene expression on Turing’s mechanism. We find extensive pathological model behaviour, exhibiting one or more of the following: temporal oscillations with no spatial structure, a failure of the Turing instability and an extreme sensitivity to the initial conditions, the growth profile and the duration of gene expression. This deviant behaviour is even more severe than observed in previous studies of Schnakenberg kinetics on exponentially growing domains in the presence of gene expression (Gaffney and Monk in Bull. Math. Biol. 68:99–130, 2006). Our results emphasise that gene expression dynamics induce unrealistic behaviour in Turing’s model for multiple choices of kinetics and thus such aberrant modelling predictions are likely to be generic. They also highlight that domain growth can no longer ameliorate the excessive sensitivity of Turing’s mechanism in the presence of gene expression time delays. The above, extensive, pathologies suggest that, in the presence of gene expression, Turing’s mechanism would generally require a novel and extensive secondary mechanism to control reaction diffusion patterning

Applicability of perturbative QCD to Λb→Λc\Lambda_b \to \Lambda_c decays

We develop perturbative QCD factorization theorem for the semileptonic heavy baryon decay $\Lambda_b \to \Lambda_c l\bar{\nu}$, whose form factors are expressed as the convolutions of hard $b$ quark decay amplitudes with universal $\Lambda_b$ and $\Lambda_c$ baryon wave functions. Large logarithmic corrections are organized to all orders by the Sudakov resummation, which renders perturbative expansions more reliable. It is observed that perturbative QCD is applicable to $\Lambda_b \to \Lambda_c$ decays for velocity transfer greater than 1.2. Under requirement of heavy quark symmetry, we predict the branching ratio $B(\Lambda_b \to \Lambda_c l{\bar\nu})\sim 2$, and determine the $\Lambda_b$ and $\Lambda_c$ baryon wave functions.Comment: 12 pages in Latex file, 3 figures in postscript files, some results are changed, but the conclusion is the sam

The influence of gene expression time delays on Gierer-Meinhardt pattern formation systems

There are numerous examples of morphogen gradients controlling long range signalling in developmental and cellular systems. The prospect of two such interacting morphogens instigating long range self-organisation in biological systems via a Turing bifurcation has been explored, postulated, or implicated in the context of numerous developmental processes. However, modelling investigations of cellular systems typically neglect the influence of gene expression on such dynamics, even though transcription and translation are observed to be important in morphogenetic systems. In particular, the influence of gene expression on a large class of Turing bifurcation models, namely those with pure kinetics such as the Gierer–Meinhardt system, is unexplored. Our investigations demonstrate that the behaviour of the Gierer–Meinhardt model profoundly changes on the inclusion of gene expression dynamics and is sensitive to the sub-cellular details of gene expression. Features such as concentration blow up, morphogen oscillations and radical sensitivities to the duration of gene expression are observed and, at best, severely restrict the possible parameter spaces for feasible biological behaviour. These results also indicate that the behaviour of Turing pattern formation systems on the inclusion of gene expression time delays may provide a means of distinguishing between possible forms of interaction kinetics. Finally, this study also emphasises that sub-cellular and gene expression dynamics should not be simply neglected in models of long range biological pattern formation via morphogens

Hall effect and resistivity in underdoped cuprates

The behaviour of the Hall ratio $R_{H}(T)$ as a function of temperature is one of the most intriguing normal state properties of cuprate superconductors. One feature of all the data is a maximum of $R_{H}(T)$ in the normal state that broadens and shifts to temperatures well above $T_c$ with decreasing doping. We show that a model of preformed pairs-bipolarons provides a selfconsistent quantitative description of $R_{H}(T)$ together with in-plane resistivity and uniform magnetic susceptibility for a wide range of doping.Comment: 4 pages, 2 figures, the model and fits were refine

On the choice of heavy baryon currents in the relativistic three-quark model

We test the sensitivity of bottom baryon observables with regard to the choice of the interpolating three-quark currents within the relativistic three-quark model. We have found that the semileptonic decay rates are clearly affected by the choice of currents, whereas the asymmetry parameters show only a very weak dependence on the choice of current.Comment: revtex, 9 page

Mass spectrum of the axial-vector hidden charmed and hidden bottom tetraquark states

In this article, we perform a systematic study of the mass spectrum of the axial-vector hidden charmed and hidden bottom tetraquark states using the QCD sum rules, and identify the $Z^+(4430)$ as an axial-vector tetraquark state tentatively.Comment: 24 pages, 38 figures, slight revisio