Observation of a charmonium-like enhancement in the gamma gamma --> omega J/psi process

We report the results of a search for a charmonium-like state produced in the process gamma gamma --> omega J/psi in the 3.9-4.2 GeV/c^2 mass region. We observe a significant enhancement, which is well-described by a resonant shape with mass M = (3915 +/- 3 +/- 2) MeV/c^2 and total width Gamma = (17 +/- 10 +/- 3) MeV. This enhancement may be related to one or more of the three charmonium-like states so far reported in the 3.90-3.95 GeV/c^2 mass region.Comment: 6 pages, 4 figure

New Particles from Belle

I report recent results on hidden charm spectroscopy from Belle. These include: observation of a near-threshold enhancement in the omega-J/psi invariant mass distribution for exclusive B-->K omega J/psi decays; evidence for the decay X(3872)-->pi+pi-pi0 J/psi, where the pi+pi-pi0 invariant mass distribution has a strong peak between 750 MeV and the kinematic limit of 775 MeV, suggesting that the process is dominated by the sub-threshold decay X-->omega J/psi; and the observation of a peak near 3940 MeV in the J/psi recoil mass spectrum for the inclusive continuum process e+e- --> J/psi X. The results are based on a study of a 287 fb-1 sample of e+e- annihilation data collected at center- of-mass energies around the Upsilon(4S) in the Belle detector at the KEKB collider.Comment: 10 pages 12 figures. Invited talk at the 1st meeting of the APS Topical Group on Hadronic Physics, Fermilab, October 24-26, 2004; revised to correct some reference

Labor Market Regulation and Employment in the Caribbean

This research project focuses on the demand side of the labor market by examining the impact which labor market regulations have had on employment creation in the English-speaking Caribbean countries of Barbados, Jamaica and Trinidad and Tobago. Although a recent IADB report on labor market reform in Latin America and the Caribbean indicates that the English-speaking Caribbean countries have a lower level of labor market inflexibility than Latin American countries, the regulatory environment in both the labor and commodity markets has had some adverse impact on employment creation in the region (IADB, 1996). Results from a study of the operations of the labor market in the Caribbean Group for Cooperation in Economic Development (CGCED) suggest that these regulatory measures do have some effect on the operation of businesses in the region (see Abt Associates, 1998).

Supersymmetric Contributions to Bs->K+K-

Inspired by the existing calculation of B->piK decays in supersymmetry (SUSY), we evaluate the dominant SUSY contributions to Bs->K+K-. We show that the observables of this process can be significantly modified in the presence of SUSY. In particular, the branching ratio can be increased considerably compared to the prediction of the standard model (SM). The effect is even more dramatic for the CP-violating asymmetries A_dir and A_mix. These asymmetries, expected to be small in the SM (A_dir is predicted to take only positive values), change drastically with SUSY contributions. The measurement of these observables can therefore be used to detect the presence of physics beyond the SM, and put constraints on its parameters.Comment: 17 pages, 2 figures. This new version contains one added reference and some minor style change

Non-factorizable Contributions to B→ππB \to \pi\pi Decays

We investigate to what extent the experimental information on $B \to \pi\pi$ branching fractions and CP asymmetries can be used to better understand the QCD dynamics in these decays. For this purpose we decompose the independent isospin amplitudes into factorizable and non-factorizable contributions. The former can be estimated within the framework of QCD factorization for exclusive $B$ decays. The latter vanish in the heavy-quark limit, $m_b \to \infty$, and are treated as unknown hadronic parameters. We discuss at some length in which way the non-factorizable contributions are treated in different theoretical and phenomenological frameworks. We point out the potential differences between the phenomenological treatment of power-corrections in the ``BBNS approach'', and the appearance of power -suppressed operators in soft-collinear effective theory (SCET). On that basis we define a handful of different (but generic) scenarios where the non-factorizable part of isospin amplitudes is parametrized in terms of three or four unknowns, which can be constrained by data. We also give some short discussion on the implications of our analysis for $B \to \pi K$ decays. In particular, since non-factorizable QCD effects in $B \to \pi \pi$ may be large, we cannot exclude sizeable non-factorizable effects, which violate $SU(3)_F$ flavour symmetry, or even isospin symmetry (via long-distance QED effects). This may help to explain certain puzzles in connection with isospin-violating observables in $B \to \pi K$ decays.Comment: published version, minor correction

A Uniform Description of the States Recently Observed at B-factories

The newly found states Y(4260), Y(4361), Y(4664) and Z$^\pm$(4430) stir broad interest in the study of spectroscopy in a typical charmonium scale. The Y(4260) which was observed earlier has been interpreted as hybrid, molecular state, and baryonium, etc. In this note we show for the first time that these new structures, which are hard to be interpreted as charmonium states, can be systematically embedded into an extended baryonium picture. According to this assignment, the so far known characters of these states are understandable. And, in the same framework, we make some predictions for experimenters to measure in the future.Comment: 6 pages in Latex. to appear in J.Phys.

A histometric analysis of chronically rejected human liver allografts: Insights into the mechanisms of bile duct loss: Direct immunologic and ischemic factors

Conspicuous pathologic features of chronic liver allograft rejection include bile duct loss and chronic obliterative arteriopathy. A quantitative histometric analysis was performed to document the extent of bile duct loss, the size of the “vanished” ducts and the extent of chronic obliterative arteriopathy and to determine whether there was any relationship between chronic obliterative arteriopathy and bile duct loss. All failed liver allograft specimens with chronic rejection were reviewed and categorized according to the degree of chronic obliterative arteriopathy, assessed by the degree of luminal narrowing of hilar hepatic artery branches. Histometric analysis of the grafts revealed: (i) there was a loss of small portal arterioles (<35 μm); (ii) bile ducts which should accompany arteries <35, 35 to 54 or 55 to 74 μm in diameter were missing, with the greatest decrease occurring among the smallest ducts; (iii) bile duct loss was seen in the absence of significant large vessel chronic obliterative arteriopathy, and (iv) the severity of arteriole and bile duct loss, as well as the size of the vanished ducts, was directly proportional to the degree of chronic obliterative arteriopathy. Furthermore, the size of the “vanished” bile ducts in liver allografts appeared to differ from the size of ducts destroyed in primary biliary cirrhosis. These studies offer indirect, but suggestive proof that two mechanisms are operative in the bile duct loss seen in chronic rejection: direct lymphocytotoxicity and ischemic damage. Copyright © 1989 American Association for the Study of Liver Disease

EM Decay of X(3872) as the 11D2(2−+)1{^1D_2}(2^{-+}) charmonium

The recently BaBar results raise the possibility that X(3872) has negative parity. This makes people reconsider assigning X(3872) to the $1{^1D_2}(c\bar c)$ state. In this paper we give a general form of the wave function of $2^{-+}$ mesons. By solving the instantaneous Bethe-Salpeter equation, we get the mass spectrum and corresponding wave functions. We calculate electromagnetic decay widths of the first $2^{-+}$ state which we assume to be the X(3872) particle. The results are $\Gamma(2^{-+}(3872)\rightarrow J/\psi\gamma) = 1.59^{+0.53}_{-0.42}$ keV, $\Gamma(2^{-+}(3872)\rightarrow \psi(2S)\gamma) = 2.87^{+1.46}_{-0.97}$ eV and $\Gamma(2^{-+}(3872)\rightarrow \psi(3770)\gamma) = 0.135^{+0.066}_{-0.047}$ keV. The ratio of branch fractions of the second and first channel is about 0.002, which is inconsistent with the experimental value $3.4\pm 1.4$. So X(3872) is unlikely to be a $2^{-+}$ charmonium state. In addition, we obtain a relatively large decay width for $2^{-+}(3872)\rightarrow h_c\gamma$ channel which is $392^{+62}_{-111}$ keV.Comment: Revised versio

Comorbidity and Autism Spectrum Disorder Research Topics: Co-Occurrence of Autism Spectrum Disorder and Achondroplasia

This Research Topic in Frontiers aims to overcome the sparsity of studies regarding comorbidity in ASD. It asks potential participants to explore; question; and when necessary; challenge conventional knowledge regarding ASD. Are standard screening instruments capable of delineating the full range of impairment in ASD in the presence of comorbidities? Given the difficulties in communication for many autistic patients; what red flags point towards the presence of comorbidities and what should constitute appropriate medical screening? How do comorbid conditions relate to maladaptive behaviors? This Research Topic will seek answers to these and other questions while raising awareness of how comorbid conditions increase both mortality and morbidity in ASD. Appropriate contributions will include research articles; case reports as well as population-based studies; information for healthcare providers; assessments for clinical management; and position statements from relevant policy making organizations