1,429 research outputs found
Fictions of Legibility. The Human Face and Body in Modern German Novels from Sophie von La Roche to Alfred Döblin
No full textGabriela Stoicea (author
Studying the p+Pb ridges using two-particle correlations and cumulants with the ATLAS detector
No full textTwo particle correlation measurements in p+Pb collisions at the LHC have shown a feature or features commonly referred to as the "ridge" in high-multiplicity events. The ridge describes a long-range correlation in relative pseudorapidity originally observed at small azimuthal angle separations. More recent measurements have shown a similar feature for pairs of particles with azimuthal angle difference near pi. Theoretical calculations assuming saturation at low x can reproduce the measured orrelations, but similarities between the transverse momentum dependence of the two-particle correlations in p+Pb and Pb+Pb collisions have also led to speculation that the ridges might arise from collective dynamics similar to that observed in Pb+Pb collisions. Results will be presented for ATLAS measurements of two-particle correlations and multi-particle cumulants in p+Pb collisions using data from the 2012 p+Pb run. The implications of these measurements for the interpretation of the ridge phenomenon will be discussed
Measurement of the inclusive isolated prompt photon cross section in pp collisions at √s = 7 TeV with the ATLAS detector
No full text"The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of root s = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb(-1). The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 -dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m(jj) < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured b (b) over bar -dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta. RI Gutierrez, Phillip\/C-1161-2011; Ferrando, James\/A-9192-2012; collins-tooth, christopher\/A-9201-2012; Perrino, Roberto\/B-4633-2010; Laurelli, Paolo\/B-1432-2012; De Cecco, Sandro\/B-1016-2012; Stoicea, Gabriel\/B-6717-2011; branchini, paolo\/A-4857-2011; Wolter, Marcin\/A-7412-2012; Rotaru, Marina\/A-3097-2011; O'Shea, Val\/G-1279-2010; Doyle, Anthony\/C-5889-2009; Buttar, Craig\/D-3706-2011; Pina, Joao \/C-4391-2012; Takai, Helio\/C-3301-2012; St.Denis, Richard\/C-8997-2012; Jones, Roger\/H-5578-2011; Britton, David\/F-2602-2010; Li, Xuefei\/C-3861-2012; Fazio, Salvatore \/G-5156-2010; Smirnova, Lidia\/D-8089-2012; Smirnov, Sergei\/F-1014-2011; Gladilin, Leonid\/B-5226-2011; Barreiro, Fernando\/D-9808-2012; Kramarenko, Victor\/E-1781-2012; Prokoshin, Fedor\/E-2795-2012; Alexa, Calin\/F-6345-2010; Pacheco Pages, Andres\/C-5353-2011; Moorhead, Gareth\/B-6634-2009; Livan, Michele\/D-7531-2012; Petrucci, Fabrizio\/G-8348-2012; Wemans, Andre\/A-6738-2012; Fabbri, Laura\/H-3442-2012; Kurashige, Hisaya\/H-4916-2012; Villa, Mauro\/C-9883-2009; Kuzhir, Polina\/H-8653-2012; Delmastro, Marco\/I-5599-2012
Search for a CP-odd Higgs boson decaying to Zh in pp collisions at root s=8 TeV with the ATLAS detector
No full textSee paper for full list of authors – 13 pages plus author list + cover pages (30 pages total), 5 figures, 2 tables, submitted to Phys. Lett. B, All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGG-2013-06/International audienceA search for a heavy, CP-odd Higgs boson, , decaying into a boson and a 125 GeV Higgs boson, , with the ATLAS detector at the LHC is presented. The search uses proton--proton collision data at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb. Decays of CP-even bosons to or pairs with the boson decaying to electron or muon pairs are considered, as well as decays with the boson decaying to neutrinos. No evidence for the production of an boson in these channels is found and the 95% confidence level upper limits derived for \sigma (gg\rightarrow A) \times \mbox{BR}(A \rightarrow Zh) \times \mbox{BR}(h \rightarrow f\bar{f}) are 0.098--0.013 pb for and 0.57--0.014 pb for in a range of 220--1000 GeV. The results are combined and interpreted in the context of two-Higgs doublet models
Search for flavour-changing neutral-current interactions of a top quark and a gluon in collisions at TeV with the ATLAS detector
No full textA search is presented for the production of a single top quark via
left-handed flavour-changing neutral-current (FCNC) interactions of a top
quark, a gluon and an up or charm quark. Two production processes are
considered: and . The analysis is based on
proton-proton collision data taken at a centre-of-mass energy of 13TeV with
the ATLAS detector at the LHC. The data set corresponds to an integrated
luminosity of 139 fb. Events with exactly one electron or muon, exactly
one -tagged jet and missing transverse momentum are selected, resembling the
decay products of a singly produced top quark. Neural networks based on
kinematic variables differentiate between events from the two signal processes
and events from background processes. The measured data are consistent with the
background-only hypothesis, and limits are set on the production cross-sections
of the signal processes: pb and pb at the 95% confidence
level, with being the sum of
branching ratios of all three leptonic decay modes of the boson. Based on
the framework of an effective field theory, the cross-section limits are
translated into limits on the strengths of the and couplings
occurring in the theory: TeV and
TeV. These bounds correspond to
limits on the branching ratios of FCNC-induced top-quark decays:
and
.Comment: 51 pages in total, author list starting page 35, 7 figures, 4 tables,
published by Eur. Phys. J. C, All figures including auxiliary figures are
available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2018-06
Properties of g→bb¯ at small opening angles in pp collisions with the ATLAS detector at √s = 13 TeV
No full textThe fragmentation of high-energy gluons at small opening angles is largely unconstrained by present measurements. Gluon splitting to
b
-quark pairs is a unique probe into the properties of gluon fragmentation because identified
b
-tagged jets provide a proxy for the quark daughters of the initial gluon. In this study, key differential distributions related to the
g
→
b
¯
b
process are measured using
33
fb
−
1
of
√
s
=
13
TeV
p
p
collision data recorded by the ATLAS experiment at the LHC in 2016. Jets constructed from charged-particle tracks, clustered with the anti-
k
t
jet algorithm with radius parameter
R
=
0.2
, are used to probe angular scales below the
R
=
0.4
jet radius. The observables are unfolded to particle level in order to facilitate direct comparisons with predictions from present and future simulations. Multiple significant differences are observed between the data and parton shower Monte Carlo predictions, providing input to improve these predictions of the main source of background events in analyses involving boosted Higgs bosons decaying into
b
-quarks
FPGA implementation of RDMA for ATLAS readout with FELIX at high luminosity LHC
No full textThe FELIX system is used as an interface between front-end electronics and commodity hardware in the server farm. FELIX is using RDMA through RoCE to transmit data from its host servers to the software readout driver using off-the-shelf networking equipment. RDMA communication is implemented using software on both end of the links. Exploring opportunities to improve data throughput as part of the high luminosity LHC upgrade, an implementation for RDMA support in the front-end FELIX FPGA is being developed. We present a proof-of-concept RDMA FPGA implementation, which will help inform the design of the FELIX platform for high luminosity LHC
Search for flavour-changing neutral-current interactions of a top quark and a gluon in pp collisions at √s=13 TeV with the ATLAS detector [Search for flavour-changing neutral-current interactions of a top quark and a gluon in pp collisions at root s=13 TeV with the ATLAS detector]
No full textA search is presented for the production of a single top quark via left-handed flavour-changing neutral-current (FCNC) interactions of a top quark, a gluon and an up or charm quark. Two production processes are considered: u+ g→ t and c+ g→ t. The analysis is based on proton–proton collision data taken at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. The data set corresponds to an integrated luminosity of 139 fb- 1. Events with exactly one electron or muon, exactly one b-tagged jet and missing transverse momentum are selected, resembling the decay products of a singly produced top quark. Neural networks based on kinematic variables differentiate between events from the two signal processes and events from background processes. The measured data are consistent with the background-only hypothesis, and limits are set on the production cross-sections of the signal processes: σ(u+g→t)×B(t→Wb)×B(W→lν)<3.0pb and σ(c+g→t)×B(t→Wb)×B(W→lν)<4.7pb at the 95% confidence level, with B(W→ lν) = 0.325 being the sum of branching ratios of all three leptonic decay modes of the W boson. Based on the framework of an effective field theory, the cross-section limits are translated into limits on the strengths of the tug and tcg couplings occurring in the theory: |CuGut|/Λ2<0.057TeV- 2 and |CuGct|/Λ2<0.14TeV- 2. These bounds correspond to limits on the branching ratios of FCNC-induced top-quark decays: B(t→ u+ g) < 0.61 × 10 - 4 and B(t→ c+ g) < 3.7 × 10 - 4
ALICE: Physics performance report, volume I
No full textCortese P, Dellacasa G, Ramello L, et al. ALICE: Physics performance report, volume I. Journal of Physics G: Nuclear and Particle Physics. 2004;30(11):1517-1763.ALICE is a general-purpose heavy-ion experiment designed to study the physics of strongly interacting matter and the quark-gluon plasma in nucleus-nucleus collisions at the LHC. It currently includes more than 900 physicists and senior engineers, from both nuclear and high-energy physics, from about 80 institutions in 28 countries. The experiment was approved in February 1997. The detailed design of the different detector systems has been laid down in a number of Technical Design Reports issued between mid-1998 and the end of 2001 and construction has started for most detectors. Since the last comprehensive information on detector and physics performance was published in the ALICE Technical Proposal in 1996, the detector as well as simulation, reconstruction and analysis software have undergone significant development. The Physics Performance Report (PPR) will give an updated and comprehensive summary of the current status and performance of the various ALICE subsystems, including updates to the Technical Design Reports, where appropriate, as well as a description of systems which have not been published in a Technical Design Report. The PPR will be published in two volumes. The current Volume I contains: 1. a short theoretical overview and an extensive reference list concerning the physics topics of interest to ALICE, 2. relevant experimental conditions at the LHC, 3. a short summary and update of the subsystem designs, and 4. a description of the offline framework and Monte Carlo generators. Volume II, which will be published separately, will contain detailed simulations of combined detector performance, event reconstruction, and analysis of a representative sample of relevant physics observables from global event characteristics to hard processes. (Some figures in this article are in colour only in the electronic version.
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