282 research outputs found

    How low can SUSY go? Matching, monojets and compressed spectra

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    If supersymmetry (SUSY) has a compressed spectrum then the current mass limits from the LHC can be drastically reduced. We consider a possible 'worst case' scenario where the gluino and/or squarks are degenerate with the lightest SUSY particle (LSP). The most sensitive searches for these compressed spectra are via the final state LSPs recoiling against initial state radiation (ISR). Therefore it is vital that the ISR is understood and possible uncertainties in the predictions are evaluated. We use both MLM (with Pythia 6) and CKKW- L (with Pythia 8) matching and vary matching scales and parton shower properties to accurately determine the theoretical uncertainties in the kinematic distributions. All current LHC SUSY and monojet analyses are employed and we find the most constraining limits come from the CMS Razor and CMS monojet searches. For a scenario of squarks degenerate with the LSP and decoupled gluinos we find Mq~>340M_{\tilde{q}}>340 GeV. For gluinos degenerate with the LSP and decoupled squarks, Mg~>500M_{\tilde{g}}>500 GeV. For equal mass squarks and gluinos degenerate with the LSP, Mq~,g~>650M_{\tilde{q},\tilde{g}}>650 GeV.Comment: References added, version submitted to ep

    Two-loop RGEs with Dirac gaugino masses

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    The set of renormalisation group equations to two loop order for general supersymmetric theories broken by soft and supersoft operators is completed. As an example, the explicit expressions for the RGEs in a Dirac gaugino extension of the (N)MSSM are presented.Comment: 10 pages + 24 pages of RGEs in appendix; no figure

    Invisible Higgs and Dark Matter

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    We investigate the possibility that a massive weakly interacting fermion simultaneously provides for a dominant component of the dark matter relic density and an invisible decay width of the Higgs boson at the LHC. As a concrete model realizing such dynamics we consider the minimal walking technicolor, although our results apply more generally. Taking into account the constraints from the electroweak precision measurements and current direct searches for dark matter particles, we find that such scenario is heavily constrained, and large portions of the parameter space are excluded.Comment: arXiv admin note: text overlap with arXiv:0912.229

    Fitting Neutrino Physics with a U(1)_R Lepton Number

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    We study neutrino physics in the context of a supersymmetric model where a continuous R-symmetry is identified with the total Lepton Number and one sneutrino can thus play the role of the down type Higgs. We show that R-breaking effects communicated to the visible sector by Anomaly Mediation can reproduce neutrino masses and mixing solely via radiative contributions, without requiring any additional degree of freedom. In particular, a relatively large reactor angle (as recently observed by the Daya Bay collaboration) can be accommodated in ample regions of the parameter space. On the contrary, if the R-breaking is communicated to the visible sector by gravitational effects at the Planck scale, additional particles are necessary to accommodate neutrino data.Comment: 19 pages, 3 figures; v2: references added, constraints updated, overall conclusions unchange

    Simulation-based design study for the passive shielding of the COSINUS dark matter experiment

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    The COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) experiment aims at the detection of dark matter-induced recoils in sodium iodide (NaI) crystals operated as scintillating cryogenic calorimeters. The detection of both scintillation light and phonons allows performing an event-by-event signal to background discrimination, thus enhancing the sensitivity of the experiment. The construction of the experimental facility is foreseen to start by 2021 at the INFN Gran Sasso National Laboratory (LNGS) in Italy. It consists of a cryostat housing the target crystals shielded from the external radioactivity by a water tank acting, at the same time, as an active veto against cosmic ray-induced events. Taking into account both environmental radioactivity and intrinsic contamination of materials used for cryostat, shielding and infrastructure, we performed a careful background budget estimation. The goal is to evaluate the number of events that could mimic or interfere with signal detection while optimising the geometry of the experimental setup. In this paper we present the results of the detailed Monte Carlo simulations we performed, together with the final design of the setup that minimises the residual amount of background particles reaching the detector volume.Comment: 12 pages, 7 figure

    Yhtenäiset vaatimukset lääketieteen ja hammaslääketieteen tohtorintutkinnolle Suomessa

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    Oulussa järjestettiin 13.6.2018 lääketieteen ja hammaslääketieteen tohtorintutkinnon konsensuskokous, jossa käytiin läpi vallitsevia käytäntöjä ja muutostarpeita. Ohjeellinen tutkinnon laajuus on neljä vuotta kokopäiväistä työtä, ja muodollisesti tutkinnon myöntää yhtä yliopistoa lukuun ottamatta aina vastaava tiedekunta. Ohjaajia on tyypillisesti kahdesta kolmeen, ja yksi on pääohjaaja. Seurantaryhmä on käytössä tai ollaan ottamassa käyttöön kaikissa yliopistoissa. Aktiivinen seurantaryhmä tukee merkittävästi ohjausprosessia. Väitöskirjojen asiantuntijoina toimivat esitarkastajat ja vastaväittäjät ovat yleensä muualta kuin suorituspaikan yliopistosta. Osittain tästä syystä suuria eroja eri yliopistojen tohtorintutkinnon vaatimusten välillä ei todettu. Haasteena väitöskirjatyössä on kliinisen työn paine ja nuorten kollegoiden ruuhkavuosien kuormittuminen, mitkä heikentävät mahdollisuuksia tutkimustyöhön. Myönteisiä muutoksia ovat olleet tohtoriopintojen systematisoituminen sekä ohjaamisen tason ja väitöskirjantekijöiden tuen paraneminen. Kaikki osallistuneet kannattivat käytäntöjen vakiinnuttamista ja yhtenäistämistä säännöllisellä konsensuskokoustyöskentelyllä.</p

    How Many Supersymmetries?

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    Supersymmetry in the gauge sector could be realized as N=1 or N=2 Supersymmetry, but the current LHC searches assume an N=1 realization. In this paper we show that squarks could be as light as few hundreds of GeV for N=2. We also describe an experimental procedure to count the number of supersymmetries, i.e. to distinguish between N=1 and N=2 supersymmetry, based on counting bins with different jet multiplicities and number of leptons.Comment: 7 pages, 3 figure

    Deep-underground dark matter search with a COSINUS detector prototype

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    Sodium iodide (NaI) based cryogenic scintillating calorimeters using quantum sensors for signal read out have shown promising first results towards a model-independent test of the annually modulating signal detected by the DAMA/LIBRA dark matter experiment. The COSINUS collaboration has previously reported on the first above-ground measurements using a dual channel readout of phonons and light based on transition edge sensors (TESs) that allows for particle discrimination on an event-by-event basis. In this letter, we outline the first underground measurement of a NaI cryogenic calorimeter read out via the novel remoTES scheme. A 3.67 g NaI absorber with an improved silicon light detector design was operated at the Laboratori Nazionali del Gran Sasso, Italy. A significant improvement in the discrimination power of ee^-/γ\gamma-events to nuclear recoils was observed with a five-fold improvement in the nuclear recoil baseline resolution, achieving σ\sigma = 441 eV. Furthermore, we present a limit on the spin-independent dark-matter nucleon elastic scattering cross-section achieving a sensitivity of O\mathcal{O}(pb) with an exposure of only 11.6 g d.Comment: 11 pages, 14 figure
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