3,780 research outputs found

    Does parton saturation at high density explain hadron multiplicities at LHC?

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    An addendum to our previous papers in Phys. Lett. B539 (2002) 46 and Phys. Lett. B502 (2001) 51, contributed to the CERN meeting "First data from the LHC heavy ion run", March 4, 2011Comment: 6 pages, contribution to the CERN meeting "First data from the LHC heavy ion run", March 4, 201

    Mathematical modeling of the aerodynamic characteristics in flight dynamics

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    Basic concepts involved in the mathematical modeling of the aerodynamic response of an aircraft to arbitrary maneuvers are reviewed. The original formulation of an aerodynamic response in terms of nonlinear functionals is shown to be compatible with a derivation based on the use of nonlinear functional expansions. Extensions of the analysis through its natural connection with ideas from bifurcation theory are indicated

    Quantifying the Effect of Non-Larmor Motion of Electrons on the Pressure Tensor

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    In space plasma, various effects of magnetic reconnection and turbulence cause the electron motion to significantly deviate from their Larmor orbits. Collectively these orbits affect the electron velocity distribution function and lead to the appearance of the "non-gyrotropic" elements in the pressure tensor. Quantification of this effect has important applications in space and laboratory plasma, one of which is tracing the electron diffusion region (EDR) of magnetic reconnection in space observations. Three different measures of agyrotropy of pressure tensor have previously been proposed, namely, A∅eA\varnothing_e, DngD_{ng} and QQ. The multitude of contradictory measures has caused confusion within the community. We revisit the problem by considering the basic properties an agyrotropy measure should have. We show that A∅eA\varnothing_e, DngD_{ng} and QQ are all defined based on the sum of the principle minors (i.e. the rotation invariant I2I_2) of the pressure tensor. We discuss in detail the problems of I2I_2-based measures and explain why they may produce ambiguous and biased results. We introduce a new measure AGAG constructed based on the determinant of the pressure tensor (i.e. the rotation invariant I3I_3) which does not suffer from the problems of I2I_2-based measures. We compare AGAG with other measures in 2 and 3-dimension particle-in-cell magnetic reconnection simulations, and show that AGAG can effectively trace the EDR of reconnection in both Harris and force-free current sheets. On the other hand, A∅eA\varnothing_e does not show prominent peaks in the EDR and part of the separatrix in the force-free reconnection simulations, demonstrating that A∅eA\varnothing_e does not measure all the non-gyrotropic effects in this case, and is not suitable for studying magnetic reconnection in more general situations other than Harris sheet reconnection.Comment: accepted by Phys. of Plasm

    Implementing A Business Intelligence (BI)/Corporate Performance Management (CPM) Solution: Challenges Faced By A Major National Retailer

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    Based on actual events, this case is concerned with the practical and managerial challenges associated with analyzing, designing and implementing a Business Intelligence (BI) / Corporate Performance Management (CPM)information technology solution in a large national retailer. Secondary issues examined include strategy, project management and conflict resolution. This case is appropriate for upper-level undergraduate and masters-level graduate courses in information technology, accounting information systems and project management. It is designed to be taught in about one class hour, and requires four to six hours of outside preparation by students.

    Upsilon Dissociation in Quark-Gluon Plasma

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    I consider the dissociation of the upsilon meson due to absorption of a thermal gluon. I discuss the dissociation rate in terms of the energy density, the number density, and the temperature of the quark-gluon plasma. I compare this to the effect due to screening.Comment: 5 pages, added calculations on screening; added figur

    Asymptotics of the colored Jones function of a knot

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    To a knot in 3-space, one can associate a sequence of Laurent polynomials, whose nnth term is the nnth colored Jones polynomial. The paper is concerned with the asymptotic behavior of the value of the nnth colored Jones polynomial at e^{\a/n}, when \a is a fixed complex number and nn tends to infinity. We analyze this asymptotic behavior to all orders in 1/n1/n when \a is a sufficiently small complex number. In addition, we give upper bounds for the coefficients and degree of the nnth colored Jones polynomial, with applications to upper bounds in the Generalized Volume Conjecture. Work of Agol-Dunfield-Storm-W.Thurston implies that our bounds are asymptotically optimal. Moreover, we give results for the Generalized Volume Conjecture when \a is near 2Ï€i2 \pi i. Our proofs use crucially the cyclotomic expansion of the colored Jones function, due to Habiro.Comment: 31 pages, 13 figure

    Improved Coulomb Correction Formulae for Bose-Einstein Correlations

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    We present improved Coulomb correction formulae for Bose-Einstein correlations including also exchange term and use them to calculate appropriate correction factors for several source functions. It is found that Coulomb correction to the exchange function in the Bose-Einstein correlations cannot be neglected.Comment: LaTex file, 8 pages, hard copies of 6 (multiple) figures available on request to [email protected] or [email protected]

    Close contacts of xenograft recipients: Ethical considerations due to risk of xenozoonosis

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    With decades of pre-clinical studies culminating in the recent clinical application of xenotransplantation, it would appear timely to provide recommendations for operationalizing oversight of xenotransplantation clinical trials. Ethical issues with clinical xenotransplantation have been described for decades, largely centering on animal welfare, the risks posed to the recipient, and public health risks posed by potential spread of xenozoonosis. Much less attention has been given to considerations relating to potentially elevated risks faced by those who may care for or otherwise have close contact with xenograft recipients. This paper examines the ethical and logistical issues raised by the potential exposure to xenozoonotic disease faced by close contacts of xenotransplant recipients—defined herein as including but not limited to caregivers, household contacts, and sexual partners— which warrants special attention given their increased risk of exposure to infection compared to the general public. We discuss implications of assent or consent by these close contacts to potentially undergo, along with the recipient, procedures for infection screening and possible quarantine. We then propose several options and recommendations for operationalizing oversight of xenotransplantation clinical trials that could account for and address close contacts’ education on and agency regarding the risk of xenozoonosis

    Proton-Antiproton Annihilation in Baryonium

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    A possible interpretation of the near-threshold enhancement in the (ppˉ)(p\bar{p})-mass spectrum in J/ψ→γppˉJ/\psi{\to}\gamma p{\bar p} is the of existence of a narrow baryonium resonance X(1860). Mesonic decays of the (ppˉ)(p\bar{p})-bound state X(1860) due to the nucleon-antinucleon annihilation are investigated in this paper. Mesonic coherent states with fixed GG-parity and PP-parity have been constructed . The Amado-Cannata-Dedoder-Locher-Shao formulation(Phys Rev Lett. {\bf 72}, 970 (1994)) is extended to the decays of the X(1860). By this method, the branch-fraction ratios of Br(X→η4π)Br(X\to \eta 4\pi), Br(X→η2π)Br(X\to \eta 2\pi) and Br(X→3η)Br(X\to 3\eta) are calculated. It is shown that if the X(1860) is a bound state of (ppˉ)(p\bar{p}), the decay channel (X→η4π)X\to \eta 4\pi) is favored over (X→η2π)(X\to \eta 2\pi). In this way, we develop criteria for distinguishing the baryonium interpretation for the near-threshold enhancement effects in (ppˉ)(p\bar{p})-mass spectrum in J/ψ→γppˉJ/\psi{\to}\gamma p{\bar p} from other possibilities. Experimental checks are expected. An intuitive picture for our results is discussed.Comment: 19 pages, 3 figure

    The heavy fermion damping rate puzzle

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    : We examine again the problem of the damping rate of a moving heavy fermion in a hot plasma within the resummed perturbative theory of Pisarski and Braaten. The ansatz for its evaluation which relates it to the imaginary part of the fermion propagator pole in the framework of a self-consistent approach is critically analyzed. As already pointed out by various authors, the only way to define the rate is through additional implementation of magnetic screening. We show in detail how the ansatz works in this case and where we disagree with other authors. We conclude that the self-consistent approach is not satisfactory.Comment: 17 page
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