2,357 research outputs found

    Fermion Portal Dark Matter

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    We study a class of simplified dark matter models in which one dark matter particle couples with a mediator and a Standard Model fermion. In such models, collider and direct detection searches probe complimentary regions of parameter space. For Majorana dark matter, direct detection covers the region near mediator-dark matter degeneracy, while colliders probe regions with a large dark matter and mediator mass splitting. For Dirac and complex dark matter, direct detection is effective for the entire region above the mass threshold, but colliders provide a strong bound for dark matter lighter than a few GeV. We also point out that dedicated searches for signatures with two jets or a mono-jet not coming from initial state radiation, along missing transverse energy can cover the remaining parameter space for thermal relic dark matter.Comment: 22 pages, 10 figures; corrections made on coannihilation parts, references added; corrections made on Majorana fermion direct detectio

    Patient Autonomy in Talmudic Context: The Patient’s ‘‘I Must Eat’’ on Yom Kippur in the Light of Contemporary Bioethics

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    In contemporary bioethics, the autonomy of the patient has assumed considerable importance. Progressing from a more limited notion of informed consent, shared decision making calls upon patients to voice the desires and preferences of their authentic self, engaging in choice among alternatives as a way to exercise deeply held values. One influential opinion in Jewish bioethics holds that Jewish law, in contradistinction to secular bioethics, limits the patient's exercise of autonomy only in those instances in which treatment choices are sensitive to preferences. Here, we analyze a discussion in the Mishna, a foundational text of rabbinic Judaism, regarding patient autonomy in the setting of religiously mandated fasting, and commentaries in the Babylonian and Palestinian Talmuds, finding both a more expansive notion of such autonomy and a potential metaphysical grounding for it in the importance of patient self-knowledge

    Lepton Portal Dark Matter

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    We study a class of simplified dark matter models in which dark matter couples directly with a mediator and a charged lepton. This class of Lepton Portal dark matter models has very rich phenomenology: it has loop generated dark matter electromagnetic moments that generate a direct detection signal; it contributes to indirect detection in the cosmic positron flux via dark matter annihilation; it provides a signature of the same-flavor, opposite-sign dilepton plus missing transverse energy at colliders. We determine the current experimental constraints on the model parameter space for Dirac fermion, Majorana fermion and complex scalar dark matter cases of the Lepton Portal framework. We also perform a collider study for the 14 TeV LHC reach with 100 inverse femtobarns for dark matter parameter space. For the complex scalar dark matter case, the LHC provides a very stringent constraint and its reach can be interpreted as corresponding to a limit as strong as two tenths of a zeptobarn on the dark matter-nucleon scattering cross section for dark matter masses up to 500 GeV. We also demonstrate that one can improve the current collider searches by using a Breit-Wigner like formula to fit the dilepton MT2 tail of the dominant diboson background.Comment: 24 pages, 8 figure

    Coloron-assisted Leptoquarks at the LHC

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    Recent searches for a first-generation leptoquark by the CMS collaboration have shown around 2.5 sigma deviations from Standard Model predictions in both the eejj and e nu jj channels. Furthermore, the eejj invariant mass distribution has another 2.8 sigma excess from the CMS right-handed W plus heavy neutrino search. We point out that additional leptoquark production from a heavy coloron decay can provide a good explanation for all three excesses. The coloron has a mass around 2.1 TeV and the leptoquark mass can vary from 550 GeV to 650 GeV. A key prediction of this model is an edge in the total m_T distribution of e nu jj events at around 2.1 TeV.Comment: 5 pages, 4 figure