Generalised morphisms of k-graphs: k-morphs

In a number of recent papers, (k+l)-graphs have been constructed from k-graphs by inserting new edges in the last l dimensions. These constructions have been motivated by C*-algebraic considerations, so they have not been treated systematically at the level of higher-rank graphs themselves. Here we introduce k-morphs, which provide a systematic unifying framework for these various constructions. We think of k-morphs as the analogue, at the level of k-graphs, of C*-correspondences between C*-algebras. To make this analogy explicit, we introduce a category whose objects are k-graphs and whose morphisms are isomorphism classes of k-morphs. We show how to extend the assignment \Lambda \mapsto C*(\Lambda) to a functor from this category to the category whose objects are C*-algebras and whose morphisms are isomorphism classes of C*-correspondences.Comment: 27 pages, four pictures drawn with Tikz. Version 2: title changed and numerous minor corrections and improvements. This version to appear in Trans. Amer. Math. So

Measuring γ\gamma in B±→K±(KK∗)DB^\pm \to K^\pm (K K^*)_D decays

We develop a method to measure the CKM angle $\gamma$ without hadronic uncertainties from the analysis of $B^\pm \to K^\pm D^0$ and K^\pm \D0bar followed by singly Cabibbo-suppressed $D$ decays to non CP-eigenstates, such as $K^\pm K^{*\mp}$. This method utilizes the interference between $b\to c\bar u s$ and $b\to u\bar c s$ decays, and we point out several attractive features of it. All the modes that need to be measured for this method are accessible in the present data.Comment: 8 page

Cross sections for the reactions e^+e^- → K^+K^-π^+π^-,K^+K^-π^0π^0, and K^+K^-K^+K^- measured using initial-state radiation events

We study the processes e^+e^- → K^+K^-π^+π^-γ, K^+K^-π^0π^0 γ, and K^+K^-K^+K^- γ, where the photon is radiated from the initial state. About 84 000, 8000, and 4200 fully reconstructed events, respectively, are selected from 454  fb^(-1) of BABAR data. The invariant mass of the hadronic final state defines the e+e- center-of-mass energy, so that the K^+K^-π^+π^- γ data can be compared with direct measurements of the e^+e^- → K^+K^-π^+π^- reaction. No direct measurements exist for the e^+e^- → K^+K^-π^0π^0 or e^+e^- → K^+K^-K^+K^- reactions, and we present an update of our previous result based on a data sample that is twice as large. Studying the structure of these events, we find contributions from a number of intermediate states and extract their cross sections. In particular, we perform a more detailed study of the e^+e^- → ϕ(1020)ππγ reaction and confirm the presence of the Y(2175) resonance in the ϕ(1020)f_0(980) and K^+K^-f_0(980) modes. In the charmonium region, we observe the J/ψ in all three final states and in several intermediate states, as well as the ψ(2S) in some modes, and measure the corresponding products of branching fraction and electron width

Assessment of animal diseases caused by bacteria resistant to antimicrobials: Poultry

open25siIn this opinion, the antimicrobial-resistant bacteria responsible for transmissible diseases that constitute a threat to poultry health have been assessed. The assessment has been performed following a methodology based on information collected by an extensive literature review and expert judgement. Details of the methodology used for this assessment are explained in a separate opinion. A global state of play is provided for: Avibacterium (Haemophilus) paragallinarum, Bordetella avium, Clostridium perfringens, Enterococcus faecalis and Enterococcus cecorum, Erysipelothrix rhusiopathiae, Escherichia coli, Gallibacterium spp., Mycoplasma synoviae, Ornithobacterium rhinotracheale, Pasteurella multocida, Riemerella anatipestifer and Staphylococcus aureus. Among those bacteria, EFSA identified Escherichia coli, Enterococcus faecalis and Enterococcus cecorum with ≥ 66% certainty as being the most relevant antimicrobial resistant bacteria in the EU based on the available evidence. The animal health impact of these most relevant bacteria, and their eligibility for being listed and categorised within the Animal Health Law Framework, will be assessed in separate scientific opinions.mixedNielsen S.S.; Bicout D.J.; Calistri P.; Canali E.; Drewe J.A.; Garin-Bastuji B.; Gonzales Rojas J.L.; Gortazar Schmidt C.; Herskin M.; Michel V.; Miranda Chueca M.A.; Padalino B.; Pasquali P.; Roberts H.C.; Spoolder H.; Stahl K.; Velarde A.; Viltrop A.; Winckler C.; Dewulf J.; Guardabassi L.; Hilbert F.; Mader R.; Baldinelli F.; Alvarez J.Nielsen S.S.; Bicout D.J.; Calistri P.; Canali E.; Drewe J.A.; Garin-Bastuji B.; Gonzales Rojas J.L.; Gortazar Schmidt C.; Herskin M.; Michel V.; Miranda Chueca M.A.; Padalino B.; Pasquali P.; Roberts H.C.; Spoolder H.; Stahl K.; Velarde A.; Viltrop A.; Winckler C.; Dewulf J.; Guardabassi L.; Hilbert F.; Mader R.; Baldinelli F.; Alvarez J

Is the entropy Sq extensive or nonextensive?

The cornerstones of Boltzmann-Gibbs and nonextensive statistical mechanics respectively are the entropies $S_{BG} \equiv -k \sum_{i=1}^W p_i \ln p_i$ and $S_{q}\equiv k (1-\sum_{i=1}^Wp_i^{q})/(q-1) (q\in{\mathbb R} ; S_1=S_{BG})$. Through them we revisit the concept of additivity, and illustrate the (not always clearly perceived) fact that (thermodynamical) extensivity has a well defined sense {\it only} if we specify the composition law that is being assumed for the subsystems (say $A$ and $B$). If the composition law is {\it not} explicitly indicated, it is {\it tacitly} assumed that $A$ and $B$ are {\it statistically independent}. In this case, it immediately follows that $S_{BG}(A+B)= S_{BG}(A)+S_{BG}(B)$, hence extensive, whereas $S_q(A+B)/k=[S_q(A)/k]+[S_q(B)/k]+(1-q)[S_q(A)/k][S_q(B)/k]$, hence nonextensive for $q \ne 1$. In the present paper we illustrate the remarkable changes that occur when $A$ and $B$ are {\it specially correlated}. Indeed, we show that, in such case, $S_q(A+B)=S_q(A)+S_q(B)$ for the appropriate value of $q$ (hence extensive), whereas $S_{BG}(A+B) \ne S_{BG}(A)+S_{BG}(B)$ (hence nonextensive).Comment: To appear in the Proceedings of the 31st Workshop of the International School of Solid State Physics ``Complexity, Metastability and Nonextensivity", held at the Ettore Majorana Foundation and Centre for Scientific Culture, Erice (Sicily) in 20-26 July 2004, eds. C. Beck, A. Rapisarda and C. Tsallis (World Scientific, Singapore, 2005). 10 pages including 1 figur