701 research outputs found

    Signatures of HyperCharge Axions in Colliders

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    If in addition to the standard model fields, a new pseudoscalar field that couples to hypercharge topological number density, the hypercharge axion, exists, it can be produced in colliders in association with photons or Z bosons, and detected by looking for its decay into photons or Z's. For a range of masses below a TeV and coupling above a fraction of 1/TeV, existing data from LEP II and the Tevatron can already put interesting constraints, and in future colliders accessible detection range is increased significantly. The hypercharge axion can help in explaining the matter-antimatter asymmetry in the universe.Comment: 11 pages, 8 figures, uses axodraw.st

    The Longitudinal Polarimeter at HERA

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    The design, construction and operation of a Compton back-scattering laser polarimeter at the HERA storage ring at DESY are described. The device measures the longitudinal polarization of the electron beam between the spin rotators at the HERMES experiment with a fractional systematic uncertainty of 1.6%. A measurement of the beam polarization to an absolute statistical precision of 0.01 requires typically one minute when the device is operated in the multi-photon mode. The polarimeter also measures the polarization of each individual electron bunch to an absolute statistical precision of 0.06 in approximately five minutes. It was found that colliding and non-colliding bunches can have substantially different polarizations. This information is important to the collider experiments H1 and ZEUS for their future longitudinally polarized electron program because those experiments use the colliding bunches only.Comment: 21 pages (Latex), 14 figures (EPS

    Integration of a smoking cessation program in the treatment protocol for patients with head and neck and lung cancer

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    Smoking is the main causative factor for development of head and neck and lung cancer. In addition, other malignancies such as bladder, stomach, colorectal, kidney and pancreatic cancer have a causative relation with smoking. Continued smoking after having been diagnosed with cancer has many negative consequences: effectiveness of radiotherapy is diminished, survival time is shortened and risks of recurrence, second primary malignancies and treatment complications are increased. In view of the significant health consequences of continued smoking, therefore, additional support for patients to stop smoking seems a logical extension of the present treatment protocols for smoking-related cancers. For prospectively examining the effect of nursing-delivered smoking cessation programme for patients with head and neck or lung cancer, 145 patients with head and neck or lung cancer enrolled into this programme over a 2-year period. Information on smoking behaviour, using a structured, programme specific questionnaire, was collected at baseline, and after 6 and 12 months. At 6 months, 58 patients (40%) had stopped smoking and at 12 months, 48 patients (33%) still had refrained from smoking. There were no differences in smoking cessation results between patients with head and neck and lung cancer. The only significant factor predicting success was whether the patient had made earlier attempts to quit smoking. A nurse-managed smoking cessation programme for patients with head and neck or lung cancer shows favourable long-term success rates. It seems logical, therefore, to integrate such a programme in treatment protocols for smoking-related cancers

    On Radiative Weak Annihilation Decays

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    We discuss a little-studied class of weak decay modes sensitive to only one quark topology at leading order in G_F: M --> m gamma, where M,m are mesons with completely distinct flavor quantum numbers. Specifically, they proceed via the annihilation of the valence quarks through a W and the emission of a single hard photon, and thus provide a clear separation between CKM and strong interaction physics. We survey relevant calculations performed to date, discuss experimental discovery potential, and indicate interesting future directions.Comment: 10 pages LaTeX, includes macros file and 9 .eps figures. Invited talk at RADCOR 2000 (5th Int. Symp. on Radiative Corrections), Carmel, CA, Sept. 200

    A No-Lose Theorem for Higgs Searches at a Future Linear Collider

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    Assuming perturbativity up to a high energy scale ∌1016\sim 10^{16} GeV, we demonstrate that a future e+e−e^+e^- linear collider operating at s=\sqrt{s} = 500 GeV with ∫L=\int{\cal L}= 500 fb−1^{-1} per year (such as the recently proposed TESLA facility) will detect a Higgs boson signal regardless of the complexity of the Higgs sector and of how the Higgs bosons decay.Comment: 4 pages, LaTe

    Sensitivity of CPT Tests with Neutral Mesons

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    The sensitivity of experiments with neutral mesons to possible indirect CPT violation is examined. It is shown that experiments conventionally regarded as equivalent can have CPT reaches differing by orders of magnitude within the framework of a minimal CPT- and Lorentz-violating extension of the standard model.Comment: 4 pages REVTeX, published in Physical Review Letter

    Reshuffling the OPE: Delocalized Operator Expansion

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    A generalization of the operator product expansion for Euclidean correlators of gauge invariant QCD currents is presented. Each contribution to the modified expansion, which is based on a delocalized multipole expansion of a perturbatively determined coefficient function, sums up an infinite series of local operators. On a more formal level the delocalized operator expansion corresponds to an optimal choice of basis sets in the dual spaces which are associated with the interplay of perturbative and nonperturbative N-point correlations in a distorted vacuum. A consequence of the delocalized expansion is the running of condensates with the external momentum. Phenomenological evidence is gathered that the gluon condensate, often being the leading nonperturbative parameter in the OPE, is indeed a function of resolution. Within a model calculation of the nonperturbative corrections to the ground state energy of a heavy quarkonium system it is shown exemplarily that the convergence properties are better than those of the OPE. Potential applications of the delocalized operator expansion in view of estimates of the violation of local quark-hadron duality are discussed.Comment: Talk given at conference Continuous advances in QCD 2002 / Arkadyfest, Minneapolis; 16 pages, 4 figure

    Discovering a Light Higgs Boson with Light

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    We evaluate the prospects for detecting a non-standard light Higgs boson with a significant branching ratio to two photons, in Run II of the Fermilab Tevatron. We derive the reach for several channels: 2γ2\gamma inclusive, 2γ+12\gamma+1 jet and 2γ+22\gamma+2 jets. We present the expected Run II limits on the branching ratio of h→γγh\to\gamma\gamma as a function of the Higgs mass, for the case of ``bosonic'', as well as ``topcolor'' Higgs bosons.Comment: 11 pages, LaTeX, 7 figures, 4 tables, uses aipproc2.sty, contributed to the Physics at Run II Workshop, analysis redone with optimized cuts and improved background estimate, references adde

    Charmed quark component of the photon wave function

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    We determine the c-anti-c component of the photon wave function on the basis of (i) the data on the transitions e+ e- -> J/psi(3096), psi(3686), psi(4040), psi(4415), (ii) partial widths of the two-photon decays eta_{c0}(2979), chi_{c0}(3415), chi_{c2}(3556) -> gamma-gamma, and (iii) wave functions of the charmonium states obtained by solving the Bethe-Salpeter equation for the c-anti-c system. Using the obtained c-anti-c component of the photon wave function we calculate the gamma-gamma decay partial widths for radial excitation 2S state, eta_{c0}(3594) -> gamma-gamma, and 2P states chi_{c0}(3849), chi_{c2}(3950) -> gamma-gamma.Comment: 20 pages, 8 figure

    Cosmological Constraint on the String Dilaton in Gauge-mediated Supersymmetry Breaking Theories

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    The dilaton field in string theories (if exists) is expected to have a mass of the order of the gravitino mass m3/2m_{3/2} which is in a range of 10−210^{-2}keV--1GeV in gauge-mediated supersymmetry breaking models. If it is the case, the cosmic energy density of coherent dilaton oscillation easily exceeds the critical density of the present universe. We show that even if this problem is solved by a late-time entropy production (thermal inflation) a stringent constraint on the energy density of the dilaton oscillation is derived from experimental upperbounds on the cosmic X(Îł\gamma)-ray backgrounds. This excludes an interesting mass region, 500keVâ‰Čm3/2â‰Č1GeV500keV \lesssim m_{3/2} \lesssim 1GeV, in gauge-mediated supersymmetry breaking models.Comment: 13 pages (RevTex file including one figure, use psfig), revised version to be published in Physical Review Letter
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