Mapping monojet constraints onto Simplified Dark Matter Models

The move towards simplified models for Run II of the LHC will allow for stronger and more robust constraints on the dark sector. However there already exists a wealth of Run I data which should not be ignored in the run-up to Run II. Here we reinterpret public constraints on generic beyond-standard-model cross sections to place new constraints on a simplified model. We make use of an ATLAS search in the monojet $+$ missing energy channel to constrain a representative simplified model with the dark matter coupling to an axial-vector $Z'$. We scan the entire parameter space of our chosen model to set the strongest current collider constraints on our model using the full 20.3 fb$^{-1}$ ATLAS 8 TeV dataset and provide predictions for constraints that can be set with 20 fb$^{-1}$ of 14 TeV data. Our technique can also be used for the interpretation of Run II data and provides a broad benchmark for comparing future constraints on simplified models.Comment: 19 pages, 6 figures; v2: added references, corrected mistake in discussion of previous results; v3: major content additions, version accepted by JHE

Constraining new resonant physics with top spin polarisation information

We provide a comprehensive analysis of the power of including top quark-polarisation information to kinematically challenging $t\bar t$ resonance searches, for which ATLAS and CMS start losing sensitivity. Following the general modeling and analysis strategies pursued by the experiments, we analyse the semi-leptonic and the di-lepton $t\bar t$ channels and show that including polarisation information can lead to large improvements in the limit setting procedures with large data sets. This will allow us to set limits for parameter choices where sensitivity from $m(t\bar t)$ is not sufficient. This highlights the importance of spin observables as part of a more comprehensive set of observables to gain sensitivity to BSM resonance searches.Comment: 13 pages, 11 figure

Sleptons without Hadrons

Multilepton searches for electroweakino and slepton pair production at hadron colliders remain some of the best means to test weak-scale supersymmetry. Searches at the CERN Large Hadron Collider, however, are limited by large diboson and top quark pair backgrounds, despite the application of traditional, central jet vetoes. In this context, we report the impact of introducing dynamic jet vetoes in searches for colorless superpartners. As a representative scenario, we consider the Drell-Yan production of a pair of right-handed smuons decaying into a dimuon system accompanied with missing transverse energy. As an exploratory step, we consider several global and local measures of the leptonic and hadronic activity to construct the veto. In most all cases, we find that employing a dynamic jet veto improves the sensitivity, independently of the integrated luminosity. The inclusion of non-perturbative multiple particle interactions and next-to-leading order jet merging does not alter this picture. Directions for further improvements are discussed.Comment: 18 pages; 7 figures; additional discussions added; journal version; results unchange

Towards resolving strongly-interacting dark sectors at colliders

Dark sectors with strong interactions have received considerable interest. Assuming the existence of a minimally coupled dark sector which runs to strong interactions in the infrared, we address the question whether the scaling behavior of this dark sector can be observed in missing energy signatures at present and future hadron colliders. We compare these findings to the concrete case of self-interacting dark matter and demonstrate that the energy dependence of high-momentum transfer final states can in principle be used to gain information about the UV structure of hidden sectors at future hadron colliders, subject to large improvements in systematic uncertainties, which could complement proof-of-principle lattice investigations. We also comment on the case of dark Abelian Uð1Þ theories

Role of hyperpolarization-activated cyclic nucleotide-gated channel HCN2 in embryonic neural stem cell proliferation and differentiation

Funding Information: Supported by grants from the K. Albin Johansson foundation, the Magnus Ehrnrooth foundation, The Finnish Society of Sciences and Letters and the Medical Society of Finland. We are grateful for the laboratory assistance provided by Jarno Hörhä. Publisher Copyright: © 2022 The AuthorsHyperpolarization-activated cyclic nucleotide-gated channels (HCN channels) are involved in spontaneous activity in many electrically active cell types such as cardiomyocytes and neurons. In this study, the role of HCN channels in proliferation and migration of Nestin and Sox2 expressing embryonic neural progenitor cells (NPC) originating from the subventricular zone (SVZ) was examined. Immunostaining and PCR data showed that the HCN2 subtype was highly expressed in these cells. Patch clamp recordings revealed a hyperpolarization-activated current, which was sensitive to inhibitors of HCN channels. Using the fluorescence dye bis-(1,3-dibutylbarbituric acid)-trimethineoxonol (DiBAC(4)(3)) we found that a prompt reduction of the extracellular K+ concentration, or exposing the cells to acute hypoxia, induced an instant hyperpolarization in the whole cell population. Recovery from low K+ induced hyperpolarization after extracellular calcium removal, or by re-oxygenation of hypoxic cells, was sensitive to ZD7288, a HCN channel inhibitor. Treatment of neurosphere cultures from the SVZ with ZD7288 caused a significant and reversible inhibition of neurosphere formation from single cells indicating that proliferation of progenitor cells was reduced. Furthermore, the migration of neuronal cells from neurospheres was considerably retarded in the presence of ZD7288. The results suggest that HCN2 channels are involved in controlling the proliferation of NPC and that HCN2 channel-induced spontaneous electrical activity may trigger the motility response of neurosphere-derived neurons in concert with other ion channels. Furthermore, the response to hypoxia suggests that HCN2 channels may trigger the chemotactic response of NPC to ischemic brain regions seen in many studies.Peer reviewe

The amphioxus (Branchiostoma floridae) genome contains a highly diversified set of G protein-coupled receptors

<p>Abstract</p> <p>Background</p> <p>G protein-coupled receptors (GPCRs) are one of the largest families of genes in mammals. <it>Branchiostoma floridae </it>(amphioxus) is one of the species most closely related species to vertebrates.</p> <p>Results</p> <p>Mining and phylogenetic analysis of the amphioxus genome showed the presence of at least 664 distinct GPCRs distributed among all the main families of GPCRs; <it>Glutamate (18)</it>, <it>Rhodopsin (570)</it>, <it>Adhesion (37)</it>, <it>Frizzled (6) </it>and <it>Secretin (16)</it>. Surprisingly, the <it>Adhesion </it>GPCR repertoire in amphioxus includes receptors with many new domains not previously observed in this family. We found many <it>Rhodopsin </it>GPCRs from all main groups including many amine and peptide binding receptors and several previously uncharacterized expansions were also identified. This genome has however no genes coding for bitter taste receptors (TAS2), the sweet and umami (TAS1), pheromone (VR1 or VR2) or mammalian olfactory receptors.</p> <p>Conclusion</p> <p>The amphioxus genome is remarkably rich in various GPCR subtypes while the main GPCR groups known to sense exogenous substances (such as Taste 2, mammalian olfactory, nematode chemosensory, gustatory, vomeronasal and odorant receptors) in other bilateral species are absent.</p

Regulation of intracellular pH by electrogenic Na+/HCO3-co-transporters in embryonic neural stem cell-derived radial glia-like cells

A stroke causes a hypoxic brain microenvironment that alters neural cell metabolism resulting in cell membrane hyperpolarization and intracellular acidosis. We studied how intracellular pH (pH(i)) is regulated in differentiated mouse neural progenitor cells during hyperpolarizing conditions, induced by prompt reduction of the extra cellular K+ concentration. We found that the radial glia-like population in differentiating embryonic neural progenitor cells, but not neuronal cells, was rapidly acidified under these conditions. However, when extra cellular calcium was removed, an instant depolarization and recovery of the pH(i), back to normal levels, took place. The rapid recovery phase seen in the absence of calcium, was dependent on extracellular bicarbonate and could be inhibited by 50859, a potent Na/HCO3 cotransporter inhibitor. Immunostaining and PCR data, showed that NBCe1 (SLC4A4) and NBCn1 (SLC4A7) were expressed in the cell population and that the pH(i) recovery in the radial glial-like cells after calcium removal was mediated mainly by the electrogenic sodium bicarbonate transporter NBCe1 (SLC4A4). Our results indicate that extracellular calcium might hamper pH(i) regulation and Na/HCO3 cotransporter activity in a brain injury microenvironment. Our findings show that the NBC-type transporters are the main pH(i) regulating systems prevailing in glia-like progenitor cells and that these calcium sensitive transporters are important for neuronal progenitor cell proliferation, survival and neural stem cell differentiation.Peer reviewe

Phenomenology for the Large Hadron Collider

The search for physics Beyond the Standard Model is the underlying motivation for the physics programme of the Large Hadron Collider at CERN. In this thesis we will present studies into the Large Hadron Collider phenomenology of dark matter inspired extensions to the Standard Model, di-Higgs + 2 jet (hhjj) production, CP violating effects in the Higgs sector, and the use of shape information from top polarisation measurements in searches for new physics. Full scans of the parameter space of Simplified Dark Matter models are demonstrated to be viable and allow for intriguing comparisons to relic density constraints. Strongly self-interacting dark sectors are shown to leave a potentially measurable imprint on the energy scaling of mediator production. The weak boson fusion induced production of hhjj turns out to be sensitive to a number of new physics effects, including CP violation in the Higgs sector. The use of top polarisation measurements to discover new physics which predicts polarised resonances is shown to be an effective way to ameliorate the loss of shape information for kinematically challenging regions of parameter space