214 research outputs found

    Heavy neutralino relic abundance with Sommerfeld enhancements - a study of pMSSM scenarios

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    We present a detailed discussion of Sommerfeld enhancements in neutralino dark matter relic abundance calculations for several popular benchmark scenarios in the general MSSM. Our analysis is focused on models with heavy wino- and higgsino-like neutralino LSP and models interpolating between these two scenarios. This work is the first phenomenological application of effective field theory methods that we have developed in earlier work and that allow for the consistent study of Sommerfeld enhancements in non-relativistic neutralino and chargino co-annihilation reactions within the general MSSM, away from the pure-wino and pure-higgsino limits.Comment: 38 pages, 14 figures, 3 table

    Non-relativistic pair annihilation of nearly mass degenerate neutralinos and charginos I. General framework and S-wave annihilation

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    We compute analytically the tree-level annihilation rates of a collection of non-relativistic neutralino and chargino two-particle states in the general MSSM, including the previously unknown off-diagonal rates. The results are prerequisites to the calculation of the Sommerfeld enhancement in the MSSM, which will be presented in subsequent work. They can also be used to obtain concise analytic expressions for MSSM dark matter pair annihilation in the present Universe for a large number of exclusive two-particle final states.Comment: LATeX, 24 pages (+ 25 pages Appendix), 11 figures; v2 - replaced incorrect version of Fig. 4 and fixed typos listed in the JHEP erratu

    Electroweak non-resonant corrections to top pair production close to threshold

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    The production of W+ W- b bbar from e+ e- collisions at energies close to the t tbar threshold is dominated by the resonant process with a nearly on-shell t tbar intermediate state. The W b pairs in the final state can also be reached through the decay of off-shell tops or through background processes containing no or only single top quarks. This non-resonant production starts to contribute at NLO to the W+ W- b bbar total cross section in the non-relativistic power-counting v ~ alpha_s ~ sqrt(alpha_EW). The NLO non-resonant corrections presented in this talk represent the non-trivial NLO electroweak corrections to the e+ e- -> W+ W- b bbar cross section in the top anti-top resonance region. In contrast to the QCD corrections which have been calculated (almost) up to NNNLO, the parametrically larger NLO electroweak contributions have not been completely known so far, but are mandatory for the required accuracy at a future linear collider. We consider the total cross section of the e+ e- -> W+ W- b bbar process and additionally implement cuts on the invariant masses of the W+ b and W- bbar pairs.Comment: Talk presented at the 35th International Conference of High Energy Physics - ICHEP2010, July 22-28, 2010, Paris France. 4 pages, 2 figure

    Relic density of wino-like dark matter in the MSSM

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    The relic density of TeV-scale wino-like neutralino dark matter in the MSSM is subject to potentially large corrections as a result of the Sommerfeld effect. A recently developed framework enables us to calculate the Sommerfeld-enhanced relic density in general MSSM scenarios, properly treating mixed states and multiple co-annihilating channels as well as including off-diagonal contributions. Using this framework, including on-shell one-loop mass splittings and running couplings and taking into account the latest experimental constraints, we perform a thorough study of the regions of parameter space surrounding the well known pure-wino scenario: namely the effect of sfermion masses being non-decoupled and of allowing non-negligible Higgsino or bino components in the lightest neutralino. We further perform an investigation into the effect of thermal corrections and show that these can safely be neglected. The results reveal a number of phenomenologically interesting but so far unexplored regions where the Sommerfeld effect is sizeable. We find, in particular, that the relic density can agree with experiment for dominantly wino neutralino dark matter with masses ranging from 1.7 to beyond 4 TeV. In light of these results the bounds from Indirect Detection on wino-like dark matter should be revisited.Comment: 49 pages, 15 figure

    Non-relativistic pair annihilation of nearly mass degenerate neutralinos and charginos III. Computation of the Sommerfeld enhancements

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    This paper concludes the presentation of the non-relativistic effective field theory formalism designed to calculate the radiative corrections that enhance the pair-annihilation cross sections of slowly moving neutralinos and charginos within the general minimal supersymmetric standard model (MSSM). While papers I and II focused on the computation of the tree-level annihilation rates that feed into the short-distance part, here we describe in detail the method to obtain the Sommerfeld factors that contain the enhanced long-distance corrections. This includes the computation of the potential interactions in the MSSM, which are provided in compact analytic form, and a novel solution of the multi-state Schr\"odinger equation that is free from the numerical instabilities generated by large mass splittings between the scattering states. Our results allow for a precise computation of the MSSM neutralino dark matter relic abundance and pair-annihilation rates in the present Universe, when Sommerfeld enhancements are important.Comment: 59 pages, 7 figures, 2 table

    A precise characterisation of the top quark electro-weak vertices at the ILC

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    Top quark production in the process e+ettˉe^+e^- \to t\bar{t} at a future linear electron positron collider with polarised beams is a powerful tool to determine indirectly the scale of new physics. The presented study, based on a detailed simulation of the ILD detector concept, assumes a centre-of-mass energy of s=500\sqrt{s}=500\,GeV and a luminosity of L=500fb1\mathcal{L}=500\,{\rm fb}^{-1} equally shared between the incoming beam polarisations of Pe,Pe+=±0.8,0.3\mathcal{P}_{e^-}, \mathcal{P}_{e^+} =\pm0.8,\mp0.3. Events are selected in which the top pair decays semi-leptonically and the cross sections and the forward-backward asymmetries are determined. Based on these results, the vector, axial vector and tensorial CPCP conserving couplings are extracted separately for the photon and the Z0Z^0 component. With the expected precision, a large number of models in which the top quark acts as a messenger to new physics can be distinguished with many standard deviations. This will dramatically improve expectations from e.g. the LHC for electro-weak couplings of the top quark.Comment: This work is an update of arXiv:1307.8102, minor changes w.r.t. v1 (typos, wrong grammar, incomplete sentences etc.

    Calculations of O(p6){\cal O}(p^6) Resonance Coupling Constants in the Scalar Sector of the ENJL Model

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    We derive the scalar resonance coupling constants of resonance chiral theory from the Extended Nambu Jona-Lasinio model by using heat-kernel expansion.Comment: 7 page

    pi/K -> e nu branching ratios to O(e^2 p^4) in Chiral Perturbation Theory

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    We calculate the ratios R_{e/mu}^{(P)} = Gamma(P -> e nu)/Gamma (P -> mu nu) (P=pi,K) in Chiral Perturbation Theory to order e^2 p^4. We complement the one- and two-loop effective theory results with a matching calculation of the local counterterm, performed within the large-NCN_C expansion. We find R_{e/mu}^{(\pi)} = (1.2352 \pm 0.0001)*10^{-4} and R_{e/mu}^{(K)} = (2.477 \pm 0.001)*10^{-5}, with uncertainty induced by the matching procedure and chiral power counting. Given the sensitivity of upcoming new measurements, our results provide a clean baseline to detect or constrain effects from weak-scale new physics in these rare decays. As a by-product, we also update the theoretical analysis of the individual pi/K -> \ell nu modes.Comment: 40 pages, 4 figures, 3 table

    Sharp acoustic vortex focusing by Fresnel-spiral zone plates

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    [EN] We report the optimal focusing of acoustic vortex beams by using flat lenses based on a Fresnelspiral diffraction grating. The flat lenses are designed by spiral-shaped Fresnel zone plates composed of one or several arms. The constructive and destructive interferences of the diffracted waves by the spiral grating result in sharp acoustic vortex beams, following the focal laws obtained in analogy with the Fresnel zone plate lenses. In addition, we show that the number of arms determines the topological charge of the vortex, allowing the precise manipulation of the acoustic wave field by flat lenses. The experimental results in the ultrasonic regime show excellent agreement with the theory and full-wave numerical simulations. A comparison with beam focusing by Archimedean spirals also showing vortex focusing is given. The results of this work may have potential applications for particle trapping, ultrasound therapy, imaging, or underwater acoustic transmitters.This work was supported by the Spanish Ministry of Economy and Innovation (MINECO) and European Union FEDER through Project Nos. FIS2015-65998-C2-1 and FIS2015-65998-C2-2. N.J. acknowledges financial support from Generalitat Valenciana through Grant No. APOSTD-2017-042.Jimenez, N.; Romero García, V.; García-Raffi, LM.; Camarena Femenia, F.; Staliunas, K. (2018). Sharp acoustic vortex focusing by Fresnel-spiral zone plates. Applied Physics Letters. 112(20):204101-1-204101-5. https://doi.org/10.1063/1.5029424S204101-1204101-511220J. Nye and M. Berry ,Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences(The Royal Society, 1974), Vol.336, pp. 165–190.Grier, D. G. (2003). A revolution in optical manipulation. Nature, 424(6950), 810-816. doi:10.1038/nature01935Volke-Sepúlveda, K., Santillán, A. 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Physical Review Letters, 117(3). doi:10.1103/physrevlett.117.034301Ye, L., Qiu, C., Lu, J., Tang, K., Jia, H., Ke, M., … Liu, Z. (2016). Making sound vortices by metasurfaces. AIP Advances, 6(8), 085007. doi:10.1063/1.4961062Naify, C. J., Rohde, C. A., Martin, T. P., Nicholas, M., Guild, M. D., & Orris, G. J. (2016). Generation of topologically diverse acoustic vortex beams using a compact metamaterial aperture. Applied Physics Letters, 108(22), 223503. doi:10.1063/1.4953075Esfahlani, H., Lissek, H., & Mosig, J. R. (2017). Generation of acoustic helical wavefronts using metasurfaces. Physical Review B, 95(2). doi:10.1103/physrevb.95.024312Jiménez, N., Picó, R., Sánchez-Morcillo, V., Romero-García, V., García-Raffi, L. M., & Staliunas, K. (2016). Formation of high-order acoustic Bessel beams by spiral diffraction gratings. Physical Review E, 94(5). doi:10.1103/physreve.94.053004Wang, T., Ke, M., Li, W., Yang, Q., Qiu, C., & Liu, Z. (2016). Particle manipulation with acoustic vortex beam induced by a brass plate with spiral shape structure. Applied Physics Letters, 109(12), 123506. doi:10.1063/1.4963185Muelas-Hurtado, R. D., Ealo, J. L., Pazos-Ospina, J. F., & Volke-Sepúlveda, K. (2018). Generation of multiple vortex beam by means of active diffraction gratings. Applied Physics Letters, 112(8), 084101. doi:10.1063/1.5016864Jiang, X., Zhao, J., Liu, S., Liang, B., Zou, X., Yang, J., … Cheng, J. (2016). Broadband and stable acoustic vortex emitter with multi-arm coiling slits. Applied Physics Letters, 108(20), 203501. doi:10.1063/1.4949337Jiménez, N., Romero-García, V., Picó, R., Cebrecos, A., Sánchez-Morcillo, V. J., Garcia-Raffi, L. M., … Staliunas, K. (2014). Acoustic Bessel-like beam formation by an axisymmetric grating. EPL (Europhysics Letters), 106(2), 24005. doi:10.1209/0295-5075/106/24005Sanchis, L., Yánez, A., Galindo, P. L., Pizarro, J., & Pastor, J. M. (2010). 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