66 research outputs found
Parameterized Post-Newtonian coefficients for Brans-Dicke gravity with d+1 dimensions
We present calculations of Post-Newtonian parameters for Brans-Dicke
tensor-scalar gravity in an arbitrary number of compact extra dimensions in
both the Jordan and Einstein conformal frames. We find that the parameter
gamma, which measures the amount of spacetime curvature per unit mass, becomes
a function of omega, the coefficient of the scalar kinetic term in the
Brans-Dicke Lagrangian. Experiment has placed strong constraints on gamma which
require that omega become negative in the Jordan frame for any number of extra
dimensions, highlighting that this formulation is not physical. We also confirm
the well-known result that a compact extra dimension can be equivalently viewed
as a massless scalar `dilaton.' In the Einstein frame, we find that the
behavior of gamma as constrained by experiment replicates that which is
predicted by string theory.Comment: 9 pages, accepted in Classical and Quantum Gravit
An X-ray Investigation of Three Supernova Remnants in the Large Magellanic Cloud
We have investigated three SNRs in the LMC using multi-wavelength data. These
SNRs are generally fainter than the known sample and may represent a previously
missed population. One of our SNRs is the second LMC remnant analyzed which is
larger than any Galactic remnant for which a definite size has been
established. The analysis of such a large remnant contributes to the
understanding of the population of highly evolved SNRs. We have obtained X-ray
images and spectra of three of these recently identified SNRs using the
XMM-Newton observatory. These data, in conjunction with pre-existing optical
emission-line images and spectra, were used to determine the physical
conditions of the optical- and X-ray-emitting gas in the SNRs. We have compared
the morphologies of the SNRs in the different wavebands. The physical
properties of the warm ionized shell were determined from the H-alpha surface
brightness and the SNR expansion velocity. The X-ray spectra were fit with a
thermal plasma model and the physical conditions of the hot gas were derived
from the model fits. Finally, we have compared our observations with
simulations of SNR evolution
Depletion of stromal cells expressing fibroblast activation protein-α from skeletal muscle and bone marrow results in cachexia and anemia.
Fibroblast activation protein-α (FAP) identifies stromal cells of mesenchymal origin in human cancers and chronic inflammatory lesions. In mouse models of cancer, they have been shown to be immune suppressive, but studies of their occurrence and function in normal tissues have been limited. With a transgenic mouse line permitting the bioluminescent imaging of FAP(+) cells, we find that they reside in most tissues of the adult mouse. FAP(+) cells from three sites, skeletal muscle, adipose tissue, and pancreas, have highly similar transcriptomes, suggesting a shared lineage. FAP(+) cells of skeletal muscle are the major local source of follistatin, and in bone marrow they express Cxcl12 and KitL. Experimental ablation of these cells causes loss of muscle mass and a reduction of B-lymphopoiesis and erythropoiesis, revealing their essential functions in maintaining normal muscle mass and hematopoiesis, respectively. Remarkably, these cells are altered at these sites in transplantable and spontaneous mouse models of cancer-induced cachexia and anemia. Thus, the FAP(+) stromal cell may have roles in two adverse consequences of cancer: their acquisition by tumors may cause failure of immunosurveillance, and their alteration in normal tissues contributes to the paraneoplastic syndromes of cachexia and anemia
Report from Working Group 3: Beyond the standard model physics at the HL-LHC and HE-LHC
This is the third out of five chapters of the final report [1] of the Workshop on Physics at HL-LHC, and perspectives on HE-LHC [2]. It is devoted to the study of the potential, in the search for Beyond the Standard Model (BSM) physics, of the High Luminosity (HL) phase of the LHC, defined as ab of data taken at a centre-of-mass energy of 14 TeV, and of a possible future upgrade, the High Energy (HE) LHC, defined as ab of data at a centre-of-mass energy of 27 TeV. We consider a large variety of new physics models, both in a simplified model fashion and in a more model-dependent one. A long list of contributions from the theory and experimental (ATLAS, CMS, LHCb) communities have been collected and merged together to give a complete, wide, and consistent view of future prospects for BSM physics at the considered colliders. On top of the usual standard candles, such as supersymmetric simplified models and resonances, considered for the evaluation of future collider potentials, this report contains results on dark matter and dark sectors, long lived particles, leptoquarks, sterile neutrinos, axion-like particles, heavy scalars, vector-like quarks, and more. Particular attention is placed, especially in the study of the HL-LHC prospects, to the detector upgrades, the assessment of the future systematic uncertainties, and new experimental techniques. The general conclusion is that the HL-LHC, on top of allowing to extend the present LHC mass and coupling reach by on most new physics scenarios, will also be able to constrain, and potentially discover, new physics that is presently unconstrained. Moreover, compared to the HL-LHC, the reach in most observables will, generally more than double at the HE-LHC, which may represent a good candidate future facility for a final test of TeV-scale new physics
Genetic Determinants for Enzymatic Digestion of Lignocellulosic Biomass Are Independent of Those for Lignin Abundance in a Maize Recombinant Inbred Population
Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector
A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements
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