295 research outputs found

    Correlated ππ\pi\pi and KKˉK\bar K exchange in the baryon-baryon interaction

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    A dynamical model for correlated two-pion and two-kaon exchange in the baryon- baryon interaction is presented, both in the scalar-isoscalar (σ\sigma) and the vector-isovector (ρ\rho) channel. The correlations between the two pseudoscalar mesons are taken into account by means of ππKKˉ\pi\pi - K\bar K amplitudes derived from a meson-exchange model, which is in line with the empirical ππ\pi\pi data. It is found that correlated KKˉK\bar K exchange plays an important role in the σ\sigma-channel for baryon-baryon states with non- vanishing strangeness. The strength of correlated ππ\pi\pi plus KKˉK\bar K exchange in the σ\sigma-channel decreases with the strangeness of the baryon- baryon system becoming more negative. The results for correlated ππ\pi\pi- exchange in the vector-isovector channel deviate from what is expected in the naive SU(3) picture for genuine ρ\rho-exchange. Shortcomings of a simplified description in terms of sharp mass σ\sigma- and ρ\rho-exchange are pointed out.Comment: 51 pages, Latex file, figures available from [email protected]

    Measurement of the Xi-p Scattering Cross Sections at Low Energy

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    In this paper we report cross-section measurements for Ξp\Xi^-p elastic and inelastic scatterings at low energy using a scintillating fiber active target. Upper limit on the total cross-section for the elastic scattering was found to be 24 mb at 90% confidence level, and the total cross section for the ΞpΛΛ\Xi^-p\to\Lambda\Lambda reaction was found to be 4.32.7+6.34.3^{+6.3}_{-2.7} mb. We compare the results with currently competing theoretical estimates.Comment: 9 page

    Compensation of the Crossing Angle with Crab Cavities at KEKB

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    Crab cavities have been installed in the KEKB B--Factory rings to compensate the crossing angle at the collision point and thus increase luminosity. The beam operation with crab crossing has been done since February 2007. This is the first experience with such cavities in colliders or storage rings. The crab cavities have been working without serious issues. While higher specific luminosity than the geometrical gain has been achieved, further study is necessary and under way to reach the prediction of simulation.Comment: Submitted to Particle Accelerator Conference 2007, MOZAKI01, Albuquerqu

    Search for the Θ+\Theta^{+} pentaquark via the πpKX\pi^-p\to K^-X reaction at 1.92 GeV/cc

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    The Θ+\Theta^+ pentaquark baryon was searched for via the πpKX\pi^-p\to K^-X reaction in a missing-mass resolution of 1.4 MeV/c2c^2(FWHM) at J-PARC. π\pi^- meson beams were incident on the liquid hydrogen target with the beam momentum of 1.92 GeV/cc. No peak structure corresponding to the Θ+\Theta^+ mass was observed. The upper limit of the production cross section averaged over the scattering angle of 2^{\circ} to 15^{\circ} in the laboratory frame was obtained to be 0.26 μ\mub/sr in the mass region of 1.51-1.55 GeV/c2c^2.The upper limit of the Θ+\Theta^+ decay width using the effective Lagrangian approach was obtained to be 0.72 MeV/c2c^2 and 3.1 MeV/c2c^2 for JΘP=1/2+J^P_{\Theta}=1/2^+ and JΘP=1/2J^P_{\Theta}=1/2^-, respectively.Comment: 5 pages, 3 figures, 1 tabl

    Optical techniques for 3D surface reconstruction in computer-assisted laparoscopic surgery

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    One of the main challenges for computer-assisted surgery (CAS) is to determine the intra-opera- tive morphology and motion of soft-tissues. This information is prerequisite to the registration of multi-modal patient-specific data for enhancing the surgeon’s navigation capabilites by observ- ing beyond exposed tissue surfaces and for providing intelligent control of robotic-assisted in- struments. In minimally invasive surgery (MIS), optical techniques are an increasingly attractive approach for in vivo 3D reconstruction of the soft-tissue surface geometry. This paper reviews the state-of-the-art methods for optical intra-operative 3D reconstruction in laparoscopic surgery and discusses the technical challenges and future perspectives towards clinical translation. With the recent paradigm shift of surgical practice towards MIS and new developments in 3D opti- cal imaging, this is a timely discussion about technologies that could facilitate complex CAS procedures in dynamic and deformable anatomical regions

    A comparison of multidisciplinary team residential rehabilitation with conventional outpatient care for the treatment of non-arthritic intra-articular hip pain in UK Military personnel:a protocol for a randomised controlled trial

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    BACKGROUND: Non-arthritic hip disorders are defined as abnormalities of the articulating surfaces of the acetabulum and femur before the onset of osteoarthritis, including intra-articular structures such as the acetabular labrum and chondral surfaces. Abnormal femoroacetabular morphology is commonly seen in young men who constitute much of the UK military population. Residential multidisciplinary team (MDT) rehabilitation for patients with musculoskeletal injuries has a long tradition in the UK military, however, there are no studies presenting empirical data on the efficacy of a residential MDT approach compared with individualised conventional outpatient treatment. With no available data, the sustainability of this care pathway has been questioned. The purpose of this randomised controlled trial is to compare the effects of a residential multidisciplinary intervention, to usual outpatient care, on the clinical outcomes of young active adults undergoing treatment for non-arthritic intra-articular hip pain. METHODS/DESIGN: The trial will be conducted at the Defence Medical Rehabilitation Centre, Headley Court, UK. One hundred military male participants with clinical indicators of non-arthritic intra-articular hip pain will be randomly allocated to either: (1) 7-day residential multidisciplinary team intervention, n = 50; (2) 6-week physiotherapist-led outpatient intervention (conventional care), n = 50. Measurements will be taken at baseline, post-treatment (1-week MDT group; 6-weeks physiotherapy group), and 12-weeks. The primary outcome measures are the function in daily living sub-scale of the Copenhagen Hip and Groin Outcome Score (HAGOS), the physical function subscale of the Non-arthritic Hip Score (NAHS), and VAS pain scale. Secondary outcomes include objective measures of physical capacity and general health. An intention-to-treat analysis will be performed using linear and mixed models. DISCUSSION: This study will be the first to assess the efficacy of intensive MDT rehabilitation, versus conventional outpatient care, for the management of non-arthritic hip pain. The results from this study will add to the evidence-base and inform clinical practice for the management of intra-articular non-arthritic hip pain and femoroacetabular impingement in young active adults. TRIAL REGISTRATION: ISRCTN Reference: ISRCTN 59255714 dated 11-Nov-2015 ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12891-016-1309-z) contains supplementary material, which is available to authorized users

    Measurement of neutrino oscillation by the K2K experiment

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    We present measurements of nu(mu) disappearance in K2K, the KEK to Kamioka long-baseline neutrino oscillation experiment. One-hundred and twelve beam-originated neutrino events are observed in the fiducial volume of Super-Kamiokande with an expectation of 158.1(-8.6)(+9.2) events without oscillation. A distortion of the energy spectrum is also seen in 58 single-ring muonlike events with reconstructed energies. The probability that the observations are explained by the expectation for no neutrino oscillation is 0.0015% (4.3 sigma). In a two-flavor oscillation scenario, the allowed Delta m(2) region at sin(2)2 theta=1 is between 1.9 and 3.5x10(-3) eV(2) at the 90% C.L. with a best-fit value of 2.8x10(-3) eV(2)
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