4,304 research outputs found
A Comprehensive Study of the Radiative Decays of and to Pseudoscalar Meson Pairs, and Search for Glueballs
Using 53 pb of annihilation data taken at
GeV, a comprehensive study has been made of the radiative decays of samples of
5.1 million and 24.5 million into pairs of pseudoscalar
mesons, , , , , and .
Product branching fractions for the radiative decays of and
to scalar resonances , and tensor
resonances have been determined, and are
discussed in relation to predicted glueballs. For radiative decays
the search for glueballs has been extended to masses between 2.5 GeV and 3.3
GeV.Comment: 21 pages, 14 figures, published in PR
Precision Measurement of the Mass of the Meson and the Binding Energy of the Meson as a Molecule
A precision measurement of the mass difference between the and
mesons has been made using 316~pb of annihilation data
taken at ~MeV using the CLEO-c detector. We obtain (stat)~~0.014(syst)~MeV, as the
average for the two decays, and .
The new measurement of leads to ~MeV,
and the currently most precise measurement of the binding energy of the
``exotic'' meson X(3872) if interpreted as a hadronic molecule,
keV.Comment: 5 pages, 3 figures, published in PRD(RC
Diagrammatic perturbation theory and the pseudogap
We study a model of quasiparticles on a two-dimensional square lattice
coupled to Gaussian distributed dynamical fields. The model describes
quasiparticles coupled to spin or charge fluctuations and is solved by a Monte
Carlo sampling of the molecular field distributions. The non-perturbative
solution is compared to various approximations based on diagrammatic
perturbation theory. When the molecular field correlations are sufficiently
weak, the diagrammatic calculations capture the qualitative aspects of the
quasiparticle spectrum. For a range of model parameters near the magnetic
boundary, we find that the quasiparticle spectrum is qualitatively different
from that of a Fermi liquid in that it shows a double peak structure, and that
the diagrammatic approximations we consider fail to reproduce, even
qualitatively, the results of the Monte Carlo calculations. This suggests that
the pseudogap induced by a coupling to antiferromagnetic fluctuations and the
spin-splitting of the quasiparticle peak induced by a coupling to ferromagnetic
spin-fluctuations lie beyond diagrammatic perturbation theory
Mecidea longula Stål (Heteroptera: Pentatomidae: Pentatominae: Mecideini) is established in south Florida
A Caribbean species of Mecidea Dallas, M. longula Stål, apparently established in south Florida, is reported from the United States for the first time. Specimens were first collected in February 2008 in a light trap operated in Miami-Dade County, Florida. Collections in that trap have continued through the present. Searches near the trap location resulted in several specimens being taken from smutgrass, Sporobolus indicus (L.), an exotic grass now established throughout much of the southeastern United States. The three North American species of Mecidea are keyed and illustrated. In addition to the Florida locality, M. longula is reported for the first time from the British Virgin Islands, St. Kitts, St. Martin, and the Turks and Caicos Islands
High Precision Measurements of the Form Factors of Pion, Kaon, and Proton at Large Timelike Momentum Transfers
High precision measurements of the form factors of proton, pion, and kaon for
timelike momentum transfers of |Q^2|=s=14.2 and 17.4 GeV^2 have been made. Data
taken with the CLEO-c detector at sqrt(s)=3.772 GeV and 4.170 GeV, with
integrated luminosities of 805 pb^-1 and 586 pb^-1, respectively, have been
used to study annihilations into pi+pi-, K+K^-, and ppbar. The
perturbative QCD prediction that at large Q^2 the quantity Q^2F(Q^2) for vector
mesons is nearly constant, and varies only weakly as the strong coupling
constant alpha_S(Q^2) is confirmed for both pions and kaons. In contrast, a
significant difference is observed between the values of the corresponding pQCD
suggested near-constant quantity, |Q^4|G_M(|Q^2|)/mu_p for protons at
|Q^2|=14.2 GeV^2 and 17.4 GeV^2. The results suggest the constancy of
|Q^2|G_M(|Q^2|)/mu_p, instead.Comment: 5 pages, 3 figures, 1 tabl
Beneficial effects of childhood selective dorsal rhizotomy in adulthood
Background: Selective dorsal rhizotomy (SDR) has been used to treat children with spastic cerebral palsy (CP) for over three decades. However, little is known about the outcomes of childhood SDR in adults. Objectives: 1) To study the effects of childhood SDR on the quality of life and ambulatory function in adult life. 2) To determine late side effects of SDR in adults. Methods: Adults (> 17.9 years) who underwent SDR in childhood (2 - 17.9 years) between 1987 and 2013 were surveyed in 2015. Patients completed a survey, including questions on demographic information, quality of life, health, surgical outcomes, motor function, manual ability, pain, braces/orthotics, post-SDR treatment, living situation, education level, work status, and side effects of SDR. Results: In our study population of 294 patients (18.0 - 37.4 years), patients received SDR during the ages of 2.0 - 17.9 years and were followed up 2.2 to 28.3 years after surgery. Eighty-four percent had spastic diplegia, 12% had spastic quadriplegia, and 4% had spastic triplegia. The majority (88%) of patients reported improved post-SDR quality of life and 1% considered the surgery detrimental. Most (83%) would recommend the procedure to others and 3% would not. However, patients who would not recommend SDR to others ambulated with a walker or were not ambulatory at all prior to SDR. The majority (83%) of patients improved (30%) or remained stable (53%) in ambulation. Twenty-nine percent of patients reported pain, mostly in the back and lower limbs, with a mean pain level of 4.4 ± 2.4 on the Numeric Pain Rating Scale (NPRS). Decreased sensation in small areas of the lower limbs was reported by 8% of patients, though this did not affect daily life. Scoliosis was diagnosed in 28%, with 40% of these patients pursuing treatment. Whether scoliosis was related to SDR is not clear, though scoliosis is known to occur in patients with CP and also in the general population. Only 4% of patients underwent spinal fusion. Orthopedic surgeries were pursued by 59% of patients. The most common orthopedic surgeries were hamstring lengthenings (31%), Achilles tendon lengthenings (18%), adductor lengthenings (16%), and derotational osteotomies (16%). Twenty-four percent of all patients later underwent hip surgery and 8% had surgeries on their knees. Conclusion: Results of this study indicate that the beneficial effects of childhood SDR extend to adulthood quality of life and ambulatory function without late side effects of surgery
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