19,649 research outputs found

    Anomalous quartic WWγγWW\gamma\gamma couplings in epep collisions at the LHeC and the FCC-he

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    We conducted a study on measuring W+WW^+W^- production and on the sensitivity limits at 95%95\% Confidence Level on thirteen anomalous couplings obtained by dimension-8 operators which are related to the anomalous quartic WWγγWW\gamma\gamma couplings. We consider the main epeγγpeW+Wpe^-p \to e^-\gamma^*\gamma^*p \to e^-W^+W^-p reaction with the sub-process γγW+W\gamma^*\gamma^* \to W^+W^- at the Large Hadron electron Collider (LHeC) and the Future Circular Collider-hadron electron (FCC-he). For the LHeC, energies of the ee^- beams are taken to be Ee=60E_e =60 and 140 GeV and the energy of the pp beams is taken to be Ep=7E_p = 7 TeV. For the FCC-he, energies of the ee^- beams are taken to be Ee=60E_e =60 and 140 GeV and the energy of the pp beams is taken to be Ep=50E_p = 50 TeV, respectively. It is interesting to notice that the LHeC and the FCC-he will lead to model-independent limits on the anomalous quartic WWγγWW\gamma\gamma couplings which are one order of magnitude stringent than the CMS Collaboration limits, in addition to being competitive with other limits reported in the literature.Comment: 28 pages, 10 Figures and 13 Table

    On the Issue of the \zeta Series Convergence and Loop Corrections in the Generation of Observable Primordial Non-Gaussianity in Slow-Roll Inflation. Part II: the Trispectrum

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    We calculate the trispectrum T_\zeta of the primordial curvature perturbation \zeta, generated during a {\it slow-roll} inflationary epoch by considering a two-field quadratic model of inflation with {\it canonical} kinetic terms. We consider loop contributions as well as tree level terms, and show that it is possible to attain very high, {\it including observable}, values for the level of non-gaussianity \tau_{NL} if T_\zeta is dominated by the one-loop contribution. Special attention is paid to the claim in JCAP {\bf 0902}, 017 (2009) [arXiv:0812.0807 [astro-ph]] that, in the model studied in this paper and for the specific inflationary trajectory we choose, the quantum fluctuations of the fields overwhelm the classical evolution. We argue that such a claim actually does not apply to our model, although more research is needed in order to understand the role of quantum diffusion. We also consider the probability that an observer in an ensemble of realizations of the density field sees a non-gaussian distribution. In that respect, we show that the probability associated to the chosen inflationary trajectory is non-negligible. Finally, the levels of non-gaussianity f_{NL} and \tau_{NL} in the bispectrum B_\zeta and trispectrum T_\zeta of \zeta, respectively, are also studied for the case in which \zeta is not generated during inflation.Comment: LaTex File, 27 pages, 8 figures. v2: Previous Section 2 has been removed. Two new sections (3 and 4) discussing the classicality condition given by Byrnes, Choi, and Hall, in JCAP 0902, 017 (2009), and the probability that an observer sees a non-gaussian distribution have been added. v3: Version accepted for publication in Physical Review

    The Triple Higgs Boson Self-Coupling at Future Linear e+e- Colliders Energies: ILC and CLIC

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    We analyzed the triple Higgs boson self-coupling at future e+ee^{+}e^{-} colliders energies, with the reactions e+ebbˉHH,ttˉHHe^{+}e^{-}\to b \bar b HH, t \bar t HH. We evaluate the total cross-sections for both bbˉHHb\bar bHH and ttˉHHt\bar tHH, and calculate the total number of events considering the complete set of Feynman diagrams at tree-level. We vary the triple coupling κλ3H\kappa\lambda_{3H} within the range κ=1\kappa=-1 and +2. The numerical computation is done for the energies expected to be available at a possible Future Linear e+ee^{+}e^{-} Collider with a center-of-mass energy 800,1000,1500800, 1000, 1500 GeVGeV and a luminosity 1000 fb1fb^{-1}. Our analysis is also extended to a center-of-mass energy 3 TeVTeV and luminosities of 1000 fb1fb^{-1} and 5000 fb1fb^{-1}. We found that for the process e+ebbˉHHe^{+}e^{-}\to b \bar b HH, the complete calculation differs only by 3% from the approximate calculation e+eZHH(Zbbˉ)e^{+}e^{-}\to ZHH(Z\to b\bar b), while for the process e+ettˉHHe^{+}e^{-}\to t \bar tHH, the expected number of events, considering the decay products of both tt and HH, is not enough to obtain an accurate determination of the triple Higgs boson self-coupling.Comment: 19 pages, 12 figure

    Momentum distributions of α\alpha-particles from decaying low-lying 12^{12}C-resonances

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    The complex scaled hyperspherical adiabatic expansion method is used to compute momentum and energy distributions of the three α\alpha-particles emerging from the decay of low-lying 12^{12}C-resonances. The large distance continuum properties of the wave functions are crucial and must be accurately calculated. We discuss separately decays of natural parity states: two 0+0^+, one 11^{-}, three 2+2^+, one 33^-, two 4+4^+, one 6+6^+, and one of each of unnatural parity, 1+1^{+}, 22^-, 3+3^+, 44^-. The lowest natural parity state of each JπJ^{\pi} decays predominantly sequentially via the 8^{8}Be ground state whereas other states including unnatural parity states predominantly decay directly to the continuum. We present Dalitz plots and systematic detailed momentum correlations of the emerging α\alpha-particles.Comment: 11 pages, 7 figures, accepted for publication in Physical Review

    Filaments in Galactic Winds Driven by Young Stellar Clusters

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    The starburst galaxy M82 shows a system of Hα\alpha-emitting filaments which extend to each side of the galactic disk. We model these filaments as the result of the interaction between the winds from a distribution of Super Stellar Clusters (SSCs). We first derive the condition necessary for producing a radiative interaction between the cluster winds (a condition which is met by the SSC distribution of M82). We then compute 3D simulations for SSC wind distributions which satisfy the condition for a radiative interaction, and also for distributions which do not satisfy this condition. We find that the highly radiative models, that result from the interaction of high metallicity cluster winds, produce a structure of Hα\alpha emitting filaments, which qualitatively agrees with the observations of the M82, while the non-radiative SSC wind interaction models do not produce filamentary structures. Therefore, our criterion for radiative interactions (which depends on the mass loss rate and the terminal velocity of the SSC winds, and the mean separation between SSCs) can be used to predict whether or not an observed galaxy should have associated Hα\alpha emitting filaments.Comment: 10 pages, 6 Figures. ApJ Accepted, August 7, 200

    The Kinematics of HH 34 from HST Images with a Nine-year Time Baseline

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    We study archival HST [S II] 6716+30 and Hα images of the HH 34 outflow, taken in 1998.71 and in 2007.83. The ~9 yr time baseline and the high angular resolution of these observations allow us to carry out a detailed proper-motion study. We determine the proper motions of the substructure of the HH 34S bow shock (from the [S II] and Hα frames) and of the aligned knots within ~30'' from the outflow source (only from the [S II] frames). We find that the present-day motions of the knots along the HH 34 jet are approximately ballistic, and that these motions directly imply the formation of a major mass concentration in ~900 yr, at a position similar to the one of the present-day HH 34S bow shock. In other words, we find that the knots along the HH 34 jet will merge to form a more massive structure, possibly resembling HH 34S

    Structure and three-body decay of 9^9Be resonances

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    The complex-rotated hyperspherical adiabatic method is used to study the decay of low-lying 9^9Be resonances into one neutron and two α\alpha-particles. We investigate the six resonances above the break-up threshold and below 6 MeV: 1/2±1/2^\pm, 3/2±3/2^\pm and 5/2±5/2^\pm. The short-distance properties of each resonance are studied, and the different angular momentum and parity configurations of the 8^8Be and 5^5He two-body substructures are determined. We compute the branching ratio for sequential decay via the 8^8Be ground state which qualitatively is consistent with measurements. We extract the momentum distributions after decay directly into the three-body continuum from the large-distance asymptotic structures. The kinematically complete results are presented as Dalitz plots as well as projections on given neutron and α\alpha-energy. The distributions are discussed and in most cases found to agree with available experimental data.Comment: 12 pages, 10 figures. To appear in Physical Review
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