221 research outputs found

    Evidence for a new Σ\Sigma^{*} resonance with JP=1/2J^P=1/2^- in the old data of KpΛπ+πK^-p\to\Lambda\pi^+\pi^- reaction

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    Distinctive patterns are predicted by quenched quark models and unquenched quark models for the lowest SU(3) baryon nonet with spin parity JP=1/2J^P=1/2^-. While the quenched quark models predict the lowest 1/21/2^- Σ\Sigma^* resonance to be above 1600 MeV, the unquenched quark models predict it to be around Σ(1385)\Sigma^*(1385) energy. Here we re-examine some old data of the \kp \to \la reaction and find that besides the well established Σ(1385)\Sigma^{*}(1385) with JP=3/2+J^P=3/2^+, there is indeed some evidence for the possible existence of a new Σ\Sigma^{*} resonance with JP=1/2J^P=1/2^- around the same mass but with broader decay width. Higher statistic data on relevant reactions are needed to clarify the situation.Comment: 7 pages, 4 figure

    Proposal and theoretical formalism for studying baryon radiative decays from J/\psi \to B^*\bar B + \bar{B^*}B \to \gamma B\bar B

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    With accumulation of high statistics data at BESIII, one may study many new interesting channels. Among them, J/\psi \to B^*\bar B + \bar{B^*}B \to \gamma B\bar B processes may provide valuable information of the radiative decays of the excited baryons (N^*,\Lambda^*,\Sigma^*,\Xi^*), and may shed light on their internal quark-gluon structure. Our estimation for the branching ratios of the nucleon excitations N^*(1440), N^*(1535) and N^*(1520) from the reaction J/\psi \to N^*\bar p + \bar N^* p \to \gamma p\bar p, indicates that these processes can be studied at BESIII with 10^{10} J/\psi events. Explicit theoretical formulae for the partial wave analysis (PWA) of the J/\psi \to B^*\bar B +\bar B^* B with B^*\to B \gamma and \bar B^*\to \bar B\gamma within covariant L-S Scheme are provided.Comment: 25 page

    Harmonic oscillator in a background magnetic field in noncommutative quantum phase-space

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    We solve explicitly the two-dimensional harmonic oscillator and the harmonic oscillator in a background magnetic field in noncommutative phase-space without making use of any type of representation. A key observation that we make is that for a specific choice of the noncommutative parameters, the time reversal symmetry of the systems get restored since the energy spectrum becomes degenerate. This is in contrast to the noncommutative configuration space where the time reversal symmetry of the harmonic oscillator is always broken.Comment: 7 pages Late

    Predicting Kidney Transplant Survival using Multiple Feature Representations for HLAs

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    Kidney transplantation can significantly enhance living standards for people suffering from end-stage renal disease. A significant factor that affects graft survival time (the time until the transplant fails and the patient requires another transplant) for kidney transplantation is the compatibility of the Human Leukocyte Antigens (HLAs) between the donor and recipient. In this paper, we propose new biologically-relevant feature representations for incorporating HLA information into machine learning-based survival analysis algorithms. We evaluate our proposed HLA feature representations on a database of over 100,000 transplants and find that they improve prediction accuracy by about 1%, modest at the patient level but potentially significant at a societal level. Accurate prediction of survival times can improve transplant survival outcomes, enabling better allocation of donors to recipients and reducing the number of re-transplants due to graft failure with poorly matched donors

    π+π+\pi^+\pi^+ and π+π\pi^+\pi^- colliding in noncommutative space

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    By studying the scattering process of scalar particle pion on the noncommutative scalar quantum electrodynamics, the non-commutative amendment of differential scattering cross-section is found, which is dependent of polar-angle and the results are significantly different from that in the commutative scalar quantum electrodynamics, particularly when cosθ±1\cos\theta\sim \pm 1. The non-commutativity of space is expected to be explored at around ΛNC\Lambda_{NC}\simTeV.Comment: Latex, 12 page

    Prompt atmospheric neutrino fluxes: perturbative QCD models and nuclear effects

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    We evaluate the prompt atmospheric neutrino flux at high energies using three different frameworks for calculating the heavy quark production cross section in QCD: NLO perturbative QCD, kTk_T factorization including low-xx resummation, and the dipole model including parton saturation. We use QCD parameters, the value for the charm quark mass and the range for the factorization and renormalization scales that provide the best description of the total charm cross section measured at fixed target experiments, at RHIC and at LHC. Using these parameters we calculate differential cross sections for charm and bottom production and compare with the latest data on forward charm meson production from LHCb at 77 TeV and at 1313 TeV, finding good agreement with the data. In addition, we investigate the role of nuclear shadowing by including nuclear parton distribution functions (PDF) for the target air nucleus using two different nuclear PDF schemes. Depending on the scheme used, we find the reduction of the flux due to nuclear effects varies from 10%10\% to 50%50 \% at the highest energies. Finally, we compare our results with the IceCube limit on the prompt neutrino flux, which is already providing valuable information about some of the QCD models.Comment: 61 pages, 25 figures, 11 table
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