Asteroseismology and Interferometry

Asteroseismology provides us with a unique opportunity to improve our understanding of stellar structure and evolution. Recent developments, including the first systematic studies of solar-like pulsators, have boosted the impact of this field of research within Astrophysics and have led to a significant increase in the size of the research community. In the present paper we start by reviewing the basic observational and theoretical properties of classical and solar-like pulsators and present results from some of the most recent and outstanding studies of these stars. We centre our review on those classes of pulsators for which interferometric studies are expected to provide a significant input. We discuss current limitations to asteroseismic studies, including difficulties in mode identification and in the accurate determination of global parameters of pulsating stars, and, after a brief review of those aspects of interferometry that are most relevant in this context, anticipate how interferometric observations may contribute to overcome these limitations. Moreover, we present results of recent pilot studies of pulsating stars involving both asteroseismic and interferometric constraints and look into the future, summarizing ongoing efforts concerning the development of future instruments and satellite missions which are expected to have an impact in this field of research.Comment: Version as published in The Astronomy and Astrophysics Review, Volume 14, Issue 3-4, pp. 217-36

Observation of associated near-side and away-side long-range correlations in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣETPb ranges and particle pT

Search for pair-produced long-lived neutral particles decaying to jets in the ATLAS hadronic calorimeter in ppcollisions at √s=8TeV

The ATLAS detector at the Large Hadron Collider at CERN is used to search for the decay of a scalar boson to a pair of long-lived particles, neutral under the Standard Model gauge group, in 20.3fb−1of data collected in proton–proton collisions at √s=8TeV. This search is sensitive to long-lived particles that decay to Standard Model particles producing jets at the outer edge of the ATLAS electromagnetic calorimeter or inside the hadronic calorimeter. No significant excess of events is observed. Limits are reported on the product of the scalar boson production cross section times branching ratio into long-lived neutral particles as a function of the proper lifetime of the particles. Limits are reported for boson masses from 100 GeVto 900 GeV, and a long-lived neutral particle mass from 10 GeVto 150 GeV

Performance of the ATLAS muon trigger in pp collisions at [Formula: see text] TeV

The performance of the ATLAS muon trigger system is evaluated with proton-proton collision data collected in 2012 at the Large Hadron Collider at a centre-of-mass energy of 8 TeV. It is primarily evaluated using events containing a pair of muons from the decay of [Formula: see text] bosons. The efficiency of the single-muon trigger is measured for muons with transverse momentum [Formula: see text] GeV, with a statistical uncertainty of less than 0.01 % and a systematic uncertainty of 0.6 %. The [Formula: see text] range for efficiency determination is extended by using muons from decays of [Formula: see text] mesons, [Formula: see text] bosons, and top quarks. The muon trigger shows highly uniform and stable performance. The performance is compared to the prediction of a detailed simulation

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.

Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field

Search for pair and single production of new heavy quarks that decay to a Z boson and a third-generation quark in pp collisions at root s=8 TeV with the ATLAS detector

Open Access. This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited

Centrality, rapidity, and transverse momentum dependence of isolated prompt photon production in lead-lead collisions at TeV measured with the ATLAS detector

Prompt photon production in $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV Pb+Pb collisions has been measured by the ATLAS experiment at the Large Hadron Collider using data collected in 2011 with an integrated luminosity of 0.14 nb$^{-1}$. Inclusive photon yields, scaled by the mean nuclear thickness function, are presented as a function of collision centrality and transverse momentum in two pseudorapidity intervals, $|\eta| < 1.37$ and $1.52 < |\eta| < 2.37$. The scaled yields in the two pseudorapidity intervals, as well as the ratios of the forward yields to those at midrapidity, are compared to the expectations from next-to-leading order perturbative QCD calculations from JETPHOX. The measured cross sections agree well with the predictions for proton-proton collisions within statistical and systematic uncertainties. Both the yields and ratios are also compared to two other pQCD calculations, one which uses the isospin content appropriate to colliding lead nuclei, and another which includes the EPS09 nuclear modifications to the nucleon parton distribution functions.Comment: 28 pages plus author list (45 pages total), 8 figures, 8 tables, Submitted to Phys. Rev. C., all figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2012-02

Observation of Associated Near-Side and Away-Side Long-Range Correlations in sqrt[s_{NN}]=5.02 TeV Proton-Lead Collisions with the ATLAS Detector.

Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in sqrt[s_{NN}]=5.02  TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1  μb^{-1} of data as a function of transverse momentum (p_{T}) and the transverse energy (ΣE_{T}^{Pb}) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) "near-side" (Δϕ∼0) correlation that grows rapidly with increasing ΣE_{T}^{Pb}. A long-range "away-side" (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣE_{T}^{Pb}, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣE_{T}^{Pb} dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos⁡2Δϕ modulation for all ΣE_{T}^{Pb} ranges and particle p_{T}

Search for W′→tb→qqbbW' \rightarrow tb \rightarrow qqbb W ′ → t b → q q b b decays in pppp p p collisions at s\sqrt{s} s = 8 TeV with the ATLAS detector

A search for a massive W′ gauge boson decaying to a top quark and a bottom quark is performed with the ATLAS detector in pp collisions at the LHC. The dataset was taken at a centre-of-mass energy of s√=8 TeVs=8 TeV and corresponds to 20.3 fb −120.3 fb −1 of integrated luminosity. This analysis is done in the hadronic decay mode of the top quark, where novel jet substructure techniques are used to identify jets from high-momentum top quarks. This allows for a search for high-mass W′ bosons in the range 1.5–3.0 TeV TeV. bb-tagging is used to identify jets originating from bb-quarks. The data are consistent with Standard Model background-only expectations, and upper limits at 95 % confidence level are set on the W′→tbW′→tb cross section times branching ratio ranging from 0.16pb0.16pb to 0.33pb0.33pb for left-handed W′W′ bosons, and ranging from 0.10pb0.10pb to 0.21pb0.21pb for W′ bosons with purely right-handed couplings. Upper limits at 95 % confidence level are set on the W′-boson coupling to tb as a function of the W′ mass using an effective field theory approach, which is independent of details of particular models predicting a W′ boson