393,495 research outputs found

    A note on the values of the weighted q-Bernstein polynomials and modified q-Genocchi numbers with weight alpha and beta via the p-adic q-integral on Zp

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    The rapid development of q-calculus has led to the discovery of new generalizations of Bernstein polynomials and Genocchi polynomials involving q-integers. The present paper deals with weighted q-Bernstein polynomials and q-Genocchi numbers with weight alpha and beta. We apply the method of generating function and p-adic q-integral representation on Zp, which are exploited to derive further classes of Bernstein polynomials and q-Genocchi numbers and polynomials. To be more precise we summarize our results as follows, we obtain some combinatorial relations between q-Genocchi numbers and polynomials with weight alpha and beta. Furthermore, we derive an integral representation of weighted q-Bernstein polynomials of degree n on Zp. Also we deduce a fermionic p-adic q-integral representation of product weighted q-Bernstein polynomials of different degrees n1,n2,...on Zp and show that it can be written with q-Genocchi numbers with weight alpha and beta which yields a deeper insight into the effectiveness of this type of generalizations. Our new generating function possess a number of interesting properties which we state in this paper.Comment: 10 page

    Competitively tight graphs

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    The competition graph of a digraph DD is a (simple undirected) graph which has the same vertex set as DD and has an edge between two distinct vertices xx and yy if and only if there exists a vertex vv in DD such that (x,v)(x,v) and (y,v)(y,v) are arcs of DD. For any graph GG, GG together with sufficiently many isolated vertices is the competition graph of some acyclic digraph. The competition number k(G)k(G) of a graph GG is the smallest number of such isolated vertices. Computing the competition number of a graph is an NP-hard problem in general and has been one of the important research problems in the study of competition graphs. Opsut [1982] showed that the competition number of a graph GG is related to the edge clique cover number θE(G)\theta_E(G) of the graph GG via θE(G)V(G)+2k(G)θE(G)\theta_E(G)-|V(G)|+2 \leq k(G) \leq \theta_E(G). We first show that for any positive integer mm satisfying 2mV(G)2 \leq m \leq |V(G)|, there exists a graph GG with k(G)=θE(G)V(G)+mk(G)=\theta_E(G)-|V(G)|+m and characterize a graph GG satisfying k(G)=θE(G)k(G)=\theta_E(G). We then focus on what we call \emph{competitively tight graphs} GG which satisfy the lower bound, i.e., k(G)=θE(G)V(G)+2k(G)=\theta_E(G)-|V(G)|+2. We completely characterize the competitively tight graphs having at most two triangles. In addition, we provide a new upper bound for the competition number of a graph from which we derive a sufficient condition and a necessary condition for a graph to be competitively tight.Comment: 10 pages, 2 figure

    Possible signatures for tetraquarks from the decays of a0(980)a_0(980), a0(1450)a_0(1450)

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    Based on the recent proposal for the tetraquarks with the mixing scheme, we investigate fall-apart decays of a0(980),a0(1450)a_0(980), a_0(1450) into two lowest-lying mesons. This mixing scheme suggests that a0(980)a_0(980) and a0(1450)a_0(1450) are the tetraquarks with the mixtures of two spin configurations of diquark and antidiquark. Due to the relative sign differences in the mixtures, the couplings of fall-apart decays into two mesons are strongly enhanced for a0(980)a_0(980) but suppressed for a0(1450)a_0(1450). We report that this expectation is supported by their experimental decays. In particular, the ratios of the associated partial decay widths, which depend on some kinematical factors and the couplings, are found to be around Γ[a0(980)πη]/Γ[a0(1450)πη]=2.512.54\Gamma [a_0(980)\rightarrow \pi \eta]/\Gamma [a_0(1450)\rightarrow \pi \eta] = 2.51-2.54, Γ[a0(980)KKˉ]/Γ[a0(1450)KKˉ]=0.520.89\Gamma [a_0(980)\rightarrow K\bar{K}]/\Gamma [a_0(1450)\rightarrow K\bar{K}] = 0.52-0.89, which seems to agree with the experimental ratios reasonably well. This agreement can be interpreted as the tetraquark signatures for a0(980),a0(1450)a_0(980), a_0(1450).Comment: 6 pages, no figures, more references are added, the version to be published in EPJ

    Coupled oscillators and Feynman's three papers

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    According to Richard Feynman, the adventure of our science of physics is a perpetual attempt to recognize that the different aspects of nature are really different aspects of the same thing. It is therefore interesting to combine some, if not all, of Feynman's papers into one. The first of his three papers is on the ``rest of the universe'' contained in his 1972 book on statistical mechanics. The second idea is Feynman's parton picture which he presented in 1969 at the Stony Brook conference on high-energy physics. The third idea is contained in the 1971 paper he published with his students, where they show that the hadronic spectra on Regge trajectories are manifestations of harmonic-oscillator degeneracies. In this report, we formulate these three ideas using the mathematics of two coupled oscillators. It is shown that the idea of entanglement is contained in his rest of the universe, and can be extended to a space-time entanglement. It is shown also that his parton model and the static quark model can be combined into one Lorentz-covariant entity. Furthermore, Einstein's special relativity, based on the Lorentz group, can also be formulated within the mathematical framework of two coupled oscillators.Comment: 31 pages, 6 figures, based on the concluding talk at the 3rd Feynman Festival (Collage Park, Maryland, U.S.A., August 2006), minor correction