Showing papers by "D. P. Benjamin published in 2017"
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TL;DR: This paper presents a short overview of the changes to the trigger and data acquisition systems during the first long shutdown of the LHC and shows the performance of the trigger system and its components based on the 2015 proton–proton collision data.
Abstract: During 2015 the ATLAS experiment recorded 3.8 fb(-1) of proton-proton collision data at a centre-of-mass energy of 13 TeV. The ATLAS trigger system is a crucial component of the experiment, respons ...
488 citations
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TL;DR: In this paper, Dijet events are studied in the proton-proton collision dataset recorded at root s = 13 TeV with the ATLAS detector at the Large Hadron Collider in 2015 and 2016.
Abstract: Dijet events are studied in the proton-proton collision dataset recorded at root s = 13 TeV with the ATLAS detector at the Large Hadron Collider in 2015 and 2016, corresponding to integrated lumino ...
248 citations
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TL;DR: Results of a search for physics beyond the Standard Model in events containing an energetic photon and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported, with model-independent limits set on the fiducial cross section.
Abstract: Results of a search for physics beyond the Standard Model in events containing an energetic photon and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are rep ...
115 citations
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TL;DR: In this article, a sample of proton-proton collisions at 8$ TeV, corresponding to an integrated luminosity of 11.4 fb$^{-1}$ collected in 2012 with the ATLAS detector at the LHC.
Abstract: The production of two prompt $J/\psi$ mesons, each with transverse momenta $p_{\mathrm{T}}>8.5$ GeV and rapidity $|y| < 2.1$, is studied using a sample of proton-proton collisions at $\sqrt{s} = 8$ TeV, corresponding to an integrated luminosity of 11.4 fb$^{-1}$ collected in 2012 with the ATLAS detector at the LHC. The differential cross-section, assuming unpolarised $J/\psi$ production, is measured as a function of the transverse momentum of the lower-$p_{\mathrm{T}}$ $J/\psi$ meson, di-$J/\psi$ $p_{\mathrm{T}}$ and mass, the difference in rapidity between the two $J/\psi$ mesons, and the azimuthal angle between the two $J/\psi$ mesons. The fraction of prompt pair events due to double parton scattering is determined by studying kinematic correlations between the two $J/\psi$ mesons. The total and double parton scattering cross-sections are compared with predictions. The effective cross-section of double parton scattering is measured to be $\sigma_{\mathrm{eff}} = 6.3 \pm 1.6 \mathrm{(stat)} \pm 1.0 \mathrm{(syst)} \pm 0.1 \mathrm{(BF)} \pm 0.1 \mathrm{(lumi)}$ mb.
96 citations
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TL;DR: In this paper, a fit to the J/ψϕ mass spectrum was performed assuming the presence of a Breit-Wigner resonance, yielding a signal of 19 ± 6 (stat) ± 3 (syst) resonance events, and resonance mass and width of 4143.4−3.0+2.9(stat)± 0.4
Abstract: The observation of the Y (4140) structure in B±→ J/ψϕK± decays produced in pp collisions at s = 1.96 TeV is reported with a statistical significance greater than 5 standard deviations. A fit to the J/ψϕ mass spectrum is performed assuming the presence of a Breit–Wigner resonance. The fit yields a signal of 19 ± 6(stat) ± 3(syst) resonance events, and resonance mass and width of 4143.4−3.0+2.9(stat) ± 0.6(syst)MeV/c2 and 15.3−6.1+10.4(stat) ± 2.5(syst)MeV/c2, respectively. The parameters of this resonance-like structure are consistent with values reported from an earlier CDF analysis.
82 citations
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TL;DR: In this article, the production cross section of a Z boson in association with jets in proton-proton collisions at root s = 13TeV was measured using data corresponding to an integrated luminosity.
Abstract: Measurements of the production cross section of a Z boson in association with jets in proton-proton collisions at root s = 13TeV are presented, using data corresponding to an integrated luminosity
60 citations
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TL;DR: In this article, the authors present searches for the Zγ decay of the Higgs boson and for narrow high-mass resonances decaying to Zγ, exploiting Z boson decays to pairs of electrons or muons.
Abstract: This article presents searches for the Zγ decay of the Higgs boson and for narrow high-mass resonances decaying to Zγ, exploiting Z boson decays to pairs of electrons or muons. The data analysis uses 36.1 fb−1 of pp collisions at √s=13 recorded by the ATLAS detector at the CERN Large Hadron Collider. The data are found to be consistent with the expected Standard Model background. The observed (expected — assuming Standard Model pp → H → Zγ production and decay) upper limit on the production cross section times the branching ratio for pp → H → Zγ is 6.6. (5.2) times the Standard Model prediction at the 95% confidence level for a Higgs boson mass of 125.09 GeV. In addition, upper limits are set on the production cross section times the branching ratio as a function of the mass of a narrow resonance between 250 GeV and 2.4 TeV, assuming spin-0 resonances produced via gluon-gluon fusion, and spin-2 resonances produced via gluon-gluon or quark-antiquark initial states. For high-mass spin-0 resonances, the observed (expected) limits vary between 88 fb (61 fb) and 2.8 fb (2.7 fb) for the mass range from 250 GeV to 2.4 TeV at the 95% confidence level.
59 citations
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TL;DR: In this article, the authors presented a search for new resonances with mass larger than 250 GeV, decaying to a Z boson and a photon, and the data were found to be consistent with the expected background in the whole mass range investigated and upper limits were set on the production cross section times decay branching ratio to Z\gamma.
53 citations
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TL;DR: In this article, a measurement of the polarisation of W bosons from t (t) over bar t decays, reconstructed in events with one high p(T) lepton and at least four jets, is presented.
Abstract: This paper presents a measurement of the polarisation of W bosons from t (t) over bar t decays, reconstructed in events with one high-p(T) lepton and at least four jets. Data from pp collisions at ...
46 citations
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TL;DR: In this article, a search for dark matter in association with a Higgs boson decaying to two photons is presented, based on data collected with the ATLAS detector, corresponding to an integrated lumino...
Abstract: A search for dark matter in association with a Higgs boson decaying to two photons is presented. This study is based on data collected with the ATLAS detector, corresponding to an integrated lumino ...
42 citations
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TL;DR: In this article, the electroweak production of a W boson in association with two jets at high dijet invariant mass was performed using root s = 7 and 8 TeV proton-proton collision data.
Abstract: Measurements of the electroweak production of a W boson in association with two jets at high dijet invariant mass are performed using root s = 7 and 8 TeV proton-proton collision data produced by t ...
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TL;DR: A measurement of the production cross section for two isolated photons in proton-proton collisions at a center-of-mass energy of root s = 8 TeV is presented in this paper.
Abstract: A measurement of the production cross section for two isolated photons in proton-proton collisions at a center-of-mass energy of root s = 8 TeV is presented. The results are based on an integrated ...
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TL;DR: The top-quark mass was measured in the all-hadronic top-antitop quark decay channel using proton-proton collisions at a centre-of-mass energy of s=8.
Abstract: The top-quark mass is measured in the all-hadronic top-antitop quark decay channel using proton-proton collisions at a centre-of-mass energy of s=8" role="presentation">s√=8 TeV with the ATLAS d ...
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TL;DR: In this paper, a search for new resonances decaying to a $W$ or $Z$ boson and a Higgs boson in collisions at the Large Hadron Collider using a total integrated luminosity of 3.2 fb$^{-1}
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TL;DR: In this paper, the authors presented a study of the production of WW or WZ boson pairs, with one W boson decaying to ev or mu v and one W or Z bosons decaying hadronically.
Abstract: This paper presents a study of the production of WW or WZ boson pairs, with one W boson decaying to ev or mu v and one W or Z boson decaying hadronically. The analysis uses 20.2 fb(-1) of root s = ...
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TL;DR: In this paper, a search for triboson production in two decay channels was carried out in the Large Hadron Collider with an expected upper bound of 730 fb with the expected limit of 560 fb in the absence of SM.
Abstract: This paper reports a search for triboson $W^{\pm}W^{\pm}W^{\mp}$ production in two decay channels ($W^{\pm}W^{\pm}W^{\mp}\rightarrow \ell^{\pm}
u\ell^{\pm}
u\ell^{\mp}
u$ and $W^{\pm}W^{\pm}W^{\mp}\rightarrow \ell^{\pm}
u\ell^{\pm}
u{}jj$ with $\ell=e, \mu$) in proton-proton collision data corresponding to an integrated luminosity of 20.3 fb$^{-1}$ at a centre-of-mass energy of 8 TeV with the ATLAS detector at the Large Hadron Collider. Events with exactly three charged leptons, or two leptons with the same electric charge in association with two jets, are selected. The total number of events observed in data is consistent with the Standard Model (SM) predictions. The observed 95 % confidence level upper limit on the SM $W^{\pm}W^{\pm}W^{\mp}$ production cross section is found to be 730 fb with an expected limit of 560 fb in the absence of SM $W^{\pm}W^{\pm}W^{\mp}$ production. Limits are also set on $WWWW$ anomalous quartic gauge couplings.
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TL;DR: The dynamics of isolated-photon plus one-, two-and three-jet production in pp collisions at a centre-of-mass energy of 8 TeV were studied with the ATLAS detector at the LHC using a data set with an...
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TL;DR: In this article, a measurement of b-hadron pair production is presented, based on a data set corresponding to an integrated luminosity of 11.4 fb−1 of proton-proton collisions recorded at √s=8 TeV with the ATLAS detector at the LHC.
Abstract: A measurement of b-hadron pair production is presented, based on a data set corresponding to an integrated luminosity of 11.4 fb−1 of proton-proton collisions recorded at √s=8 TeV with the ATLAS detector at the LHC. Events are selected in which a b-hadron is reconstructed in a decay channel containing J/ψ → μμ, and a second b-hadron is reconstructed in a decay channel containing a muon. Results are presented in a fiducial volume defined by kinematic requirements on three muons based on those used in the analysis. The fiducial cross section is measured to be 17.7 ± 0.1(stat.) ± 2.0(syst.) nb. A number of normalised differential cross sections are also measured, and compared to predictions from the Pythia8, Herwig++, MadGraph5_aMC@NLO+Pythia8 and Sherpa event generators, providing new constraints on heavy flavour production.
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TL;DR: In this paper, a search for direct top squark pair production resulting in events with either a same-flavour opposite-sign dilepton pair with invariant mass compatible with a Z boson or a pair of jets compatible with the Standard Model (SM) Higgs boson (h) is presented.
Abstract: A search for direct top squark pair production resulting in events with either a same-flavour opposite-sign dilepton pair with invariant mass compatible with a Z boson or a pair of jets compatible with a Standard Model (SM) Higgs boson (h) is presented. Requirements on the missing transverse momentum, together with additional selections on leptons, jets, jets identified as originating from b-quarks are imposed to target the other decay products of the top squark pair. The analysis is performed using proton-proton collision data at root s = 13 TeV collected with the ATLAS detector at the LHC in 20152016, corresponding to an integrated luminosity of 36.1 fb(-1). No excess is observed in the data with respect to the SM predictions. The results are interpreted in two sets of models. In the first set, direct production of pairs of lighter top squarks ((t) over tilde (1)) with long decay chains involving Z or Higgs bosons is considered. The second set includes direct pair production of the heavier top squark pairs ((t) over tilde (2)) decaying via (t) over tilde (2) -> Z (t) over tilde (1) or (t) over tilde (2) -> h (t) over tilde (1). The results exclude at 95% confidence level (t) over tilde (2) and (t) over tilde (1) masses up to about 800 GeV, extending the exclusion region of supersymmetric parameter space covered by previous LHC searches.
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TL;DR: In this article, an observable ratio of cross sections is defined for events containing jets and large missing transverse momentum in the plane transverse to the proton beams at the Large Hadron Collider, which can be used to constrain new physics models beyond those shown in this paper.
Abstract: Observables sensitive to the anomalous production of events containing hadronic jets and missing momentum in the plane transverse to the proton beams at the Large Hadron Collider are presented. The observables are defined as a ratio of cross sections, for events containing jets and large missing transverse momentum to events containing jets and a pair of charged leptons from the decay of a $Z/\gamma ^*$ boson. This definition minimises experimental and theoretical systematic uncertainties in the measurements. This ratio is measured differentially with respect to a number of kinematic properties of the hadronic system in two phase-space regions, one inclusive single-jet region and one region sensitive to vector-boson-fusion topologies. The data are found to be in agreement with the Standard Model predictions and used to constrain a variety of theoretical models for dark-matter production, including simplified models, effective field theory models, and invisible decays of the Higgs boson. The measurements use 3.2 fb$^{-1}$ of proton–proton collision data recorded by the ATLAS experiment at a centre-of-mass energy of 13 $\text {TeV}$ and are fully corrected for detector effects, meaning that the data can be used to constrain new-physics models beyond those shown in this paper.
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TL;DR: In this article, the cross section of a top-quark pair produced in association with a photon is measured in proton-proton collisions at a center-of-mass energy of root s = 8 TeV with 20.2 fb(-1) of data collected b...
Abstract: The cross section of a top-quark pair produced in association with a photon is measured in proton-proton collisions at a centre-of-mass energy of root s = 8 TeV with 20.2 fb(-1) of data collected b ...
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TL;DR: In this paper, measurements of dijet Pt correlations in Pb+Pb and pp collisions at a nucleon-nucleon center-of-mass energy of root s(NN) = 2.76 TeV are presented.
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TL;DR: While the kinematics of the jets from top-quark decays are described well, the generators show differing levels of agreement with the measurements of observables that depend on the production of additional jets.
Abstract: Measurements of jet activity in top-quark pair events produced in proton-proton collisions are presented, using 3.2 fb of pp collision data at a centre-of-mass energy of 13 TeV collected by the ATL ...
15 Nov 2017
TL;DR: In this article, the authors presented a set of observables sensitive to the anomalous production of hadronic jets and missing momentum in the plane transverse to the proton beams at the Large Hadron Collider.
Abstract: Observables sensitive to the anomalous production
of events containing hadronic jets and missing momentum
in the plane transverse to the proton beams at the Large
Hadron Collider are presented. The observables are defined
as a ratio of cross sections, for events containing jets and large
missing transverse momentum to events containing jets and a
pair of charged leptons from the decay of a Z/γ ∗ boson. This
definition minimises experimental and theoretical systematic
uncertainties in the measurements. This ratio is measured
differentially with respect to a number of kinematic properties
of the hadronic system in two phase-space regions; one
inclusive single-jet region and one region sensitive to vectorboson-fusion
topologies. The data are found to be in agreement
with the Standard Model predictions and used to constrain
a variety of theoretical models for dark-matter production,
including simplified models, effective field theory models,
and invisible decays of the Higgs boson. The measurements
use 3.2 fb−1 of proton–proton collision data recorded
by the ATLAS experiment at a centre-of-mass energy of
13 TeV and are fully corrected for detector effects, meaning
that the data can be used to constrain new-physics models
beyond those shown in this paper.
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TL;DR: In this article, a measurement of the inclusive production cross section of isolated prompt photons in proton-antiproton collisions at center-of-mass energy 1.96 is presented.
Abstract: A measurement of the inclusive production cross section of isolated prompt photons in proton-antiproton collisions at center-of-mass energy $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ is presented. The results are obtained using the full Run II data sample collected with the Collider Detector at the Fermilab Tevatron, which corresponds to an integrated luminosity of $9.5\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. The cross section is measured as a function of photon transverse energy, ${E}_{T}^{\ensuremath{\gamma}}$, in the range $30l{E}_{T}^{\ensuremath{\gamma}}l500\text{ }\text{ }\mathrm{GeV}$ and in the pseudorapidity region $|{\ensuremath{\eta}}^{\ensuremath{\gamma}}|l1.0$. The results are compared with predictions from parton-shower Monte Carlo models at leading order in QCD and from next-to-leading-order perturbative QCD calculations. The latter show good agreement with the measured cross section.
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TL;DR: Aaboud, M. et al. as mentioned in this paper corrected the original version of this article and the copyright holder was wrong in the HTML code of the original article and corrected it.
Abstract: Author(s): Aaboud, M; Aad, G; Abbott, B; Abdallah, J; Abdinov, O; Abeloos, B; Abidi, SH; AbouZeid, OS; Abraham, NL; Abramowicz, H; Abreu, H; Abreu, R; Abulaiti, Y; Acharya, BS; Adachi, S; Adamczyk, L; Adelman, J; Adersberger, M; Adye, T; Affolder, AA; Agatonovic-Jovin, T; Agheorghiesei, C; Aguilar-Saavedra, JA; Ahlen, SP; Ahmadov, F; Aielli, G; Akatsuka, S; Akerstedt, H; Akesson, TPA; Akilli, E; Akimov, AV; Alberghi, GL; Albert, J; Albicocco, P; Verzini, MJA; Aleksa, M; Aleksandrov, IN; Alexa, C; Alexander, G; Alexopoulos, T; Alhroob, M; Ali, B; Aliev, M; Alimonti, G; Alison, J; Alkire, SP; Allbrooke, BMM; Allen, BW; Allport, PP; Aloisio, A; Alonso, A; Alonso, F; Alpigiani, C; Alshehri, AA; Alstaty, M; Gonzalez, BA; Piqueras, DA; Alviggi, MG; Amadio, BT; Coutinho, YA; Amelung, C; Amidei, D; Santos, SPAD; Amorim, A; Amoroso, S; Amundsen, G; Anastopoulos, C; Ancu, LS; Andari, N; Andeen, T; Anders, CF; Anders, JK; Anderson, KJ; Andreazza, A; Andrei, V; Angelidakis, S; Angelozzi, I; Angerami, A; Anisenkov, AV; Anjos, N; Annovi, A; Antel, C; Antonelli, M; Antonov, A; Antrim, DJ | Abstract: Unfortunately, in the original version of this article the copyright holder was wrong in the HTML. The original article has been corrected.
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TL;DR: Aaltonen et al. as discussed by the authors reported on a measurement of the $D^{+}$-meson production cross section as a function of transverse momentum in proton-antiproton collisions at 196 TeV center-of-mass energy, using the full data set collected by the Collider Detector at Fermilab in Tevatron Run II.
Abstract: Author(s): Aaltonen, T; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Apollinari, G; Appel, JA; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Bae, T; Barbaro-Galtieri, A; Barnes, VE; Barnett, BA; Barria, P; Bartos, P; Bauce, M; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Bland, KR; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brigliadori, L; Bromberg, C; Brucken, E; Budagov, J; Budd, HS; Burkett, K; Busetto, G; Bussey, P; Butti, P; Buzatu, A; Calamba, A; Camarda, S; Campanelli, M; Canelli, F; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cerri, A; Cerrito, L; Chen, YC; Chertok, M; Chiarelli, G; Chlachidze, G; Cho, K; Chokheli, D; Clark, A; Clarke, C; Convery, ME; Conway, J; Corbo, M; Cordelli, M; Cox, CA; Cox, DJ; Cremonesi, M; Cruz, D; Cuevas, J; Culbertson, R; d'Ascenzo, N; Datta, M; de Barbaro, P; Demortier, L | Abstract: We report on a measurement of the $D^{+}$-meson production cross section as a function of transverse momentum ($p_T$) in proton-antiproton ($p\bar{p}$) collisions at 196 TeV center-of-mass energy, using the full data set collected by the Collider Detector at Fermilab in Tevatron Run II and corresponding to 10 fb$^{-1}$ of integrated luminosity We use $D^{+} \to K^-\pi^+\pi^+$ decays fully reconstructed in the central rapidity region $|y|l1$ with transverse momentum down to 15 GeV/$c$, a range previously unexplored in $p\bar{p}$ collisions Inelastic $p\bar{p}$-scattering events are selected online using minimally-biasing requirements followed by an optimized offline selection The $K^-\pi^+\pi^+$ mass distribution is used to identify the $D^+$ signal, and the $D^+$ transverse impact-parameter distribution is used to separate prompt production, occurring directly in the hard scattering process, from secondary production from $b$-hadron decays We obtain a prompt $D^+$ signal of 2950 candidates corresponding to a total cross section $\sigma(D^+, 15 l p_T l 145~\mbox{GeV/}c, |y|l1) = 719 \pm 68 (\mbox{stat}) \pm 93 (\mbox{syst})~\mu$b While the measured cross sections are consistent with theoretical estimates in each $p_T$ bin, the shape of the observed $p_T$ spectrum is softer than the expectation from quantum chromodynamics The results are unique in $p\bar{p}$ collisions and can improve the shape and uncertainties of future predictions
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TL;DR: In this article, a measurement of the tau + jets final state using only the hadronic decays of tau lepton is presented, and the measurement is p = t (t) over bar + X production cross section.
Abstract: A measurement of the inclusive pp -> t (t) over bar + X production cross section in the tau + jets final state using only the hadronic decays of the tau lepton is presented. The measurement is p ...