66 research outputs found

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

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    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.

    Positive Parity Scalar Mesons in the 1-2 GeV Mass Range

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    Based on the observation that K_0(1430) is lighter than its SU_3 counterpart, a_0(1450), we examine the possibility that these particles, together with f_0(1370), f_0(1500) and f_0(1710), fill a tetraquark recurrence of the sub-GeV 0^{++} nonet mixed with a glueball state. We find the picture to be consistent with the known data about the three f_0 resonances, more than the q-qbar hypothesis. Conventional spin-orbit coupling suggests the q-qbar, P-wave, nonet to lie around 1200 MeV. We review possible experimental indications of a scalar isovector resonance at 1.29 GeV, first observed by OBELIX in p-pbar annihilation.Comment: 12 pages, 9 figures. Extended version. References added. Results and conclusions unchange

    How Resonances can synchronise with Thresholds

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    The mechanism by which a threshold may capture a resonance is examined. It involves a threshold cusp interfering constructively with either or both (i) a resonance produced via confinement, (ii) attractive t- and u-channel exchanges. The fo(980), X(3872) and Z(4430) are studied in detail. The fo(980) provides a valuable model of the locking mechanism. The X(3872) is too narrow to be fitted by a cusp, and requires either a resonance or virtual state. The Z(4430) can be fitted as a resonance but also can be fitted successfully by a cusp with no nearby resonant pole.Comment: 19 pages, 6 figures. Replaces 0709.125

    J/Psi strong couplings to the vector mesons

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    We present a study of the cross sections J/Psi X --> D^(*) \bar D^(*) (X = rho, Phi) based on the calculation of the effective tri- and four-linear couplings J/Psi (X) D^(*) \bar D^(*) within a constituent quark model. In particular, the details of the calculation of the four-linear couplings J/Psi X D^(*)\bar D^(*) are given. The results obtained have been used in a recent analysis of J/Psi absorption by the hot hadron gas formed in peripheral heavy-ion collisions at SPS energies.Comment: 12 pages, 3 figure

    Heavy Quarkonium Physics

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    This report is the result of the collaboration and research effort of the Quarkonium Working Group over the last three years. It provides a comprehensive overview of the state of the art in heavy-quarkonium theory and experiment, covering quarkonium spectroscopy, decay, and production, the determination of QCD parameters from quarkonium observables, quarkonia in media, and the effects on quarkonia of physics beyond the Standard Model. An introduction to common theoretical and experimental tools is included. Future opportunities for research in quarkonium physics are also discussed.Comment: xviii + 487 pages, 260 figures. The full text is also available at the Quarkonium Working Group web page: http://www.qwg.to.infn.i

    Anogenital distance in human male and female newborns: a descriptive, cross-sectional study

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    BACKGROUND: In animal studies of the effects of hormonally active agents, measurement of anogenital distance (AGD) is now routine, and serves as a bioassay of fetal androgen action. Although measurement of AGD in humans has been discussed in the literature, to our knowledge it has been measured formally in only two descriptive studies of females. Because AGD has been an easy-to-measure, sensitive outcome in animals studies, we developed and implemented an anthropometric protocol for measurement of AGD in human males as well as females. METHODS: We first evaluated the reliability of the AGD measures in 20 subjects. Then measurements were taken on an additional 87 newborns (42 females, 45 males). All subjects were from Morelos, Mexico. RESULTS: The reliability (Pearson r) of the AGD measure was, for females 0.50, and for males, 0.64. The between-subject variation in AGD, however, was much greater than the variation due to measurement error. The AGD measure was about two-fold greater in males (mean, 22 mm) than in females (mean, 11 mm), and there was little overlap in the distributions for males and females. CONCLUSION: The sexual dimorphism of AGD in humans comprises prima facie evidence that this outcome may respond to in utero exposure to hormonally active agents

    Autoimmune encephalomyelitis in NOD mice is not initially a progressive multiple sclerosis model.

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    OBJECTIVE: Despite progress in treating relapsing multiple sclerosis (MS), effective inhibition of nonrelapsing progressive MS is an urgent, unmet, clinical need. Animal models of MS, such as experimental autoimmune encephalomyelitis (EAE), provide valuable tools to examine the mechanisms contributing to disease and may be important for developing rational therapeutic approaches for treatment of progressive MS. It has been suggested that myelin oligodendrocyte glycoprotein (MOG) peptide residues 35-55 (MOG35-55 )-induced EAE in nonobese diabetic (NOD) mice resembles secondary progressive MS. The objective was to determine whether the published data merits such claims. METHODS: Induction and monitoring of EAE in NOD mice and literature review. RESULTS: It is evident that the NOD mouse model lacks validity as a progressive MS model as the individual course seems to be an asynchronous, relapsing-remitting neurodegenerative disease, characterized by increasingly poor recovery from relapse. The seemingly progressive course seen in group means of clinical score is an artifact of data handling and interpretation. INTERPRETATION: Although MOG35-55 -induced EAE in NOD mice may provide some clues about approaches to block neurodegeneration associated with the inflammatory penumbra as lesions form, it should not be used to justify trials in people with nonactive, progressive MS. This adds further support to the view that drug studies in animals should universally adopt transparent raw data deposition as part of the publication process, such that claims can adequately be interrogated. This transparency is important if animal-based science is to remain a credible part of translational research in MS.Stichting MS ResearchWellcome TrustMedical Research CouncilNational Multiple Sclerosis Society. Grant Number: RG4132A5/
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