4,728 research outputs found

    Measuring FL(x,Q2)/F2(x,Q2)F_L(x,Q^2)/F_2(x,Q^2) from Azimuthal Asymmetries in Deep Inelastic Scattering

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    We demonstrate that the angular distribution of hadrons produced in semi-inclusive deep inelastic final states is related to the inclusive longitudinal structure function. This relation could provide a new method of accessing FL(x,Q2)F_L(x,Q^2) in deep inelastic scattering measurements.Comment: 3 pages, LaTeX, The complete paper is also available via anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ttp00/ttp00-03/ or via www at http://www-ttp.physik.uni-karlsruhe.de/Preprints

    Are magnetic monopoles hadrons?

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    The charges of magnetic monopoles are constrained to a multiple of 2π2\pi times the inverse of the elementary unit electric charge. In the standard model, quarks have fractional charge, raising the question of whether the basic magnetic monople unit is a multiple of 2π/e2 \pi/e or three times that. A simple lattice construction shows how a magnetic monopole of the lower strength is possible if it interacts with gluonic fields as well. Such a monopole is thus a hadron. This is consistent with the construction of magnetic monopoles in grand unified theories.Comment: Poster presented at Lattice2004(topology), Fermilab, June 21-26, 2004. 3 pages, 5 figure

    The FDA Black Box Warning System: The Utmost in Drug and Patient Safety?

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    THE FDA BLACK BOX WARNING SYSTEM: THE UTMOST IN DRUG AND PATIENT SAFETY? Andrew Georgi (Sponsored by Paul Barash, MD, and Loreta Grecu, MD). Department of Anesthesiology, Yale University School of Medicine, New Haven, CT. Of the 7856 pharmaceutical products under the purview of the Food and Drug Administration (FDA), over six hundred have a black box warning (BBW). As the FDAs highest level of warning included on drug package inserts, this notation is reserved for those drugs that pose significant risks leading to death or serious injury. However, the types of warnings that warrant this distinction have not been clearly identified and are not always readily justifiable. In addition, great variability exists among the drugs resources charged with transmitting this critical information to healthcare professionals and the public. The objective of this paper is to establish the most comprehensive list of drugs with a BBW, classify their content according to organ systems, and in doing so evaluate the consistency of information presented by these widely-used drug resources. This was accomplished by cross-referencing and analyzing the drug BBW information from four resources: DailyMed, Micromedex, Facts & Comparisons, and BlackBoxRx. Six hundred and thirty-five drug/drug combinations were identified as having a BBW. The most frequently affected organ systems were cardiovascular and pulmonary with 200/635 and 144/635 drug BBWs, respectively. DailyMed was the most comprehensive list with 551/635 drugs, still a shortfall of 13%. The four lists were in complete agreement for 416/635 (65%) of the drugs listed. This highlights the FDAs need to review the black box warning system and determine how best to communicate this drug information accurately and efficiently to the healthcare community

    Comment on "The Phenomenology of a Nonstandard Higgs Boson in W_L W_L Scattering"

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    We show that in Composite Higgs models, the coupling of the Higgs resonance to a pair of WW bosons is weaker than the corresponding Standard Model coupling, provided the Higgs arises from electroweak doublets only. This is partly due to the effects of the nonlinear realization of the chiral symmetries at the compositeness scale.Comment: 6 pages, BU-HEP 94-2

    Thermal Phase Transitions and Gapless Quark Spectra in Quark Matter at High Density

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    Thermal color superconducting phase transitions in three-flavor quark matter at high baryon density are investigated in the Ginzburg-Landau (GL) approach. We constructed the GL potential near the boundary with a normal phase by taking into account nonzero quark masses, electric charge neutrality, and color charge neutrality. We found that the density of states averaged over paired quarks plays a crucial role in determining the phases near the boundary. By performing a weak coupling calculation of the parameters characterizing the GL potential terms of second order in the pairing gap, we show that three successive second-order phase transitions take place as the temperature increases: a modified color-flavor locked phase (ud, ds, and us pairings) -> a ``dSC'' phase (ud and ds pairings) -> an isoscalar pairing phase (ud pairing) -> a normal phase (no pairing). The Meissner masses of the gluons and the number of gapless quark modes are also studied analytically in each of these phases.Comment: 15 pages, 6 figure

    Hidden Gauge Symmetries: A New Possibility at the Colliders

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    We consider a new physics possibility at the colliders: the observation of TeV scale massive vector bosons in the non-adjoint representations under the Standard Model (SM) gauge symmetry. To have a unitary and renormalizable theory, we propose a class of models with gauge symmetry ∏iGi×SU(3)Câ€Č×SU(2)Lâ€Č×U(1)Yâ€Č\prod_i G_i \times SU(3)'_C \times SU(2)'_L \times U(1)'_Y where the SM fermions and Higgs fields are singlets under the hidden gauge symmetry ∏iGi\prod_i G_i, and such massive vector bosons appear after the gauge symmetry is spontaneously broken down to the SM gauge symmetry. We discuss the model with SU(5) hidden gauge symmetry in detail, and comment on the generic phenomenological implications.Comment: RevTex4, 5 pages, Discussions and References added, PLB versio

    Comparison of 1/mQ^2 Corrections in Mesons and Baryons

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    We extend our relativistic quark model to the study of the decay Lambda_b -> Lambda_c ell nu and verify that the model satisfies the heavy-quark symmetry constraints at order 1/mQ^2. We isolate a strong dependence on a parameter which measures the relative distortion in the light-quark wave functions of the Lambda_b and Lambda_c. This parameter and the 1/mQ^2 corrections turn out to be small. The dependence on a corresponding parameter in the meson case leads to large 1/mQ^2 corrections.Comment: 9 pages, LaTeX, 3 self-contained LaTeX figures in separate fil

    Nonperturbative Matching for Field Theories with Heavy Fermions

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    We examine a paradox, suggested by Banks and Dabholkar, concerning nonperturbative effects in an effective field theory which is obtained by integrating out a generation of heavy fermions, where the heavy fermion masses arise from Yukawa couplings. They argue that light fermions in the effective theory appear to decay via instanton processes, whereas their decay is forbidden in the full theory. We resolve this paradox by showing that such processes in fact do not occur in the effective theory, due to matching corrections which cause the relevant light field configurations to have infinite action.Comment: 10 pages, no figures, uses harvmac, Harvard University Preprint HUTP-93/A03

    Fermionic Hopf solitons and Berry's phase in topological surface superconductors

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    A central theme in many body physics is emergence - new properties arise when several particles are brought together. Particularly fascinating is the idea that the quantum statistics may be an emergent property. This was first noted in the Skyrme model of nuclear matter, where a theory formulated entirely in terms of a bosonic order parameter field contains fermionic excitations. These excitations are smooth field textures, and believed to describe neutrons and protons. We argue that a similar phenomenon occurs in topological insulators when superconductivity gaps out their surface states. Here, a smooth texture is naturally described by a three component real vector. Two components describe superconductivity, while the third captures the band topology. Such a vector field can assume a 'knotted' configuration in three dimensional space - the Hopf texture - that cannot smoothly be unwound. Here we show that the Hopf texture is a fermion. To describe the resulting state, the regular Landau-Ginzburg theory of superconductivity must be augmented by a topological Berry phase term. When the Hopf texture is the cheapest fermionic excitation, striking consequences for tunneling experiments are predicted
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