Emanuele Bagnaschi

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Researcher at INFN Laboratori Nazionali di Frascati

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E. Bagnaschi (DESY), M. Borsato (Santiago de Compostela U.), K. Sakurai (Durham U., Dept. of Math. and Durham U., IPPP and Warsaw U.), O. Buchmueller (Imperial Coll., London), R. Cavanaugh (Fermilab and Illinois U., Chicago), V. Chobanova (Santiago de Compostela U.), M. Citron (Imperial Coll., London), J.C. Costa (Imperial Coll., London), A. De Roeck (CERN and Antwerp U.), M.J. Dolan (Melbourne U.), J.R. Ellis (King’s Coll. London and CERN), H. Flächer (Bristol U.), S. Heinemeyer (Cantabria Inst. of Phys.), G. Isidori (Zurich U.), M. Lucio (Santiago de Compostela U.), F. Luo (Tokyo U., IPMU), D. Martínez Santos (Santiago de Compostela U.), K.A. Olive (Minnesota U., Theor. Phys. Inst.), A. Richards (Imperial Coll., London), G. Weiglein (Imperial Coll., London)

Eur.Phys.J.C 77 (2017) 4, 268

DOI: 10.1140/epjc/s10052-017-4810-0

e-Print: 1612.05210 [hep-ph]

We perform a likelihood analysis of the minimal anomaly-mediated supersymmetry-breaking (mAMSB) model using constraints from cosmology and accelerator experiments. We find that either a wino-like or a Higgsino-like neutralino LSP, $\tilde{\chi }^0_{1}$​, may provide the cold dark matter (DM), both with similar likelihoods. The upper limit on the DM density from Planck and other experiments enforces $m_{\tilde{\chi }^0_{1}} \lesssim 3~\mathrm{TeV}$ after the inclusion of Sommerfeld enhancement in its annihilations. If most of the cold DM density is provided by the $\tilde{\chi }^0_{1}$, the measured value of the Higgs mass favours a limited range of $\tan \beta \sim 5$ (and also for $\tan \beta \sim 45$ if $\mu > 0$) but the scalar mass $m_0$​ is poorly constrained. In the wino-LSP case, $m_{3/2}$​ is constrained to about $900~\mathrm{TeV}$ and $m_{\tilde{\chi }^0_{1}}$​ to $2.9\pm 0.1~\mathrm {TeV}$, whereas in the Higgsino-LSP case $m_{3/2}$​ has just a lower limit $\gtrsim 650~\mathrm{TeV}$ ($\gtrsim 480~\mathrm {TeV}$) and $m_{\tilde{\chi }^0_{1}}$ is constrained to $1.12 ~(1.13) \pm 0.02~\mathrm {TeV}$ in the $\mu >0$ ($\mu <0$) scenario. In neither case can the anomalous magnetic moment of the muon, $(g-2)_\mu$​, be improved significantly relative to its Standard Model (SM) value, nor do flavour measurements constrain the model significantly, and there are poor prospects for discovering supersymmetric particles at the LHC, though there are some prospects for direct DM detection. On the other hand, if the $\tilde{\chi}^0_{1}$ contributes only a fraction of the cold DM density, future LHC -based searches for gluinos, squarks and heavier chargino and neutralino states as well as disappearing track searches in the wino-like LSP region will be relevant, and interference effects enable $\mathrm{BR}(B_{s, d} \rightarrow \mu ^+\mu^-)$ to agree with the data better than in the SM in the case of wino-like DM with $\mu > 0$.

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