Showing papers by "E. Romero Adam published in 2018"
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TL;DR: In this paper, a search for new phenomena in final states with an energetic jet and large missing transverse momentum is reported, and the results are translated into exclusion limits in models with pair-produced weakly interacting dark-matter candidates, large extra spatial dimensions, and supersymmetric particles in several compressed scenarios.
Abstract: Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses proton-proton collision data corresponding to an integrated luminosity of 36.1 fb−1 at a centre-of-mass energy of 13 TeV collected in 2015 and 2016 with the ATLAS detector at the Large Hadron Collider. Events are required to have at least one jet with a transverse momentum above 250 GeV and no leptons (e or μ). Several signal regions are considered with increasing requirements on the missing transverse momentum above 250 GeV. Good agreement is observed between the number of events in data and Standard Model predictions. The results are translated into exclusion limits in models with pair-produced weakly interacting dark-matter candidates, large extra spatial dimensions, and supersymmetric particles in several compressed scenarios.
358 citations
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TL;DR: The performance of the missing transverse momentum reconstruction with the ATLAS detector is evaluated using data collected in proton–proton collisions at the LHC at a centre-of-mass energy of 13 TeV in 2015.
Abstract: The performance of the missing transverse momentum ( ETmiss ) reconstruction with the ATLAS detector is evaluated using data collected in proton-proton collisions at the LHC at a centre-of-mass energy of 13 TeV in 2015. To reconstruct ETmiss , fully calibrated electrons, muons, photons, hadronically decaying τ-leptons , and jets reconstructed from calorimeter energy deposits and charged-particle tracks are used. These are combined with the soft hadronic activity measured by reconstructed charged-particle tracks not associated with the hard objects. Possible double counting of contributions from reconstructed charged-particle tracks from the inner detector, energy deposits in the calorimeter, and reconstructed muons from the muon spectrometer is avoided by applying a signal ambiguity resolution procedure which rejects already used signals when combining the various ETmiss contributions. The individual terms as well as the overall reconstructed ETmiss are evaluated with various performance metrics for scale (linearity), resolution, and sensitivity to the data-taking conditions. The method developed to determine the systematic uncertainties of the ETmiss scale and resolution is discussed. Results are shown based on the full 2015 data sample corresponding to an integrated luminosity of 3.2fb-1 .
208 citations
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TL;DR: In this paper, the mass of the $W$ boson was measured based on proton-proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC.
Abstract: A measurement of the mass of the $W$ boson is presented based on proton-proton collision data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS detector at the LHC, and corresponding to 4.6 fb$^{-1}$ of integrated luminosity. The selected data sample consists of $7.8 \times 10^6$ candidates in the $W\rightarrow \mu
u$ channel and $5.9 \times 10^6$ candidates in the $W\rightarrow e
u$ channel. The $W$-boson mass is obtained from template fits to the reconstructed distributions of the charged lepton transverse momentum and of the $W$ boson transverse mass in the electron and muon decay channels, yielding \begin{eqnarray} m_W &=& 80370 \pm 7 \, (\textrm{stat.}) \pm 11 \, (\textrm{exp. syst.}) \pm 14 \, (\textrm{mod. syst.}) \, \textrm{MeV} &=& 80370 \pm 19 \, \textrm{MeV}, \end{eqnarray} where the first uncertainty is statistical, the second corresponds to the experimental systematic uncertainty, and the third to the physics-modelling systematic uncertainty. A measurement of the mass difference between the $W^+$ and $W^-$ bosons yields $m_{W^+}-m_{W^-} = -29 \pm 28$ MeV.
195 citations
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TL;DR: A search for doubly charged Higgs bosons with pairs of prompt, isolated, highly energetic leptons with the same electric charge is presented, fitting the dilepton mass spectra in several exclusive signal regions.
Abstract: A search for doubly charged Higgs bosons with pairs of prompt, isolated, highly energetic leptons with the same electric charge is presented. The search uses a proton–proton collision data sample at a centre-of-mass energy of 13 TeV corresponding to 36.1 $$\text {fb}^{-1}$$
of integrated luminosity recorded in 2015 and 2016 by the ATLAS detector at the LHC. This analysis focuses on the decays $$H^{\pm \pm }\rightarrow e^{\pm }e^{\pm }$$
, $$H^{\pm \pm }\rightarrow e^{\pm }\mu ^{\pm }$$
and $$H^{\pm \pm }\rightarrow \mu ^{\pm }\mu ^{\pm }$$
, fitting the dilepton mass spectra in several exclusive signal regions. No significant evidence of a signal is observed and corresponding limits on the production cross-section and consequently a lower limit on $$m(H^{\pm \pm })$$
are derived at 95% confidence level. With $$\ell ^{\pm }\ell ^{\pm }=e^{\pm }e^{\pm }/\mu ^{\pm }\mu ^{\pm }/e^{\pm }\mu ^{\pm }$$
, the observed lower limit on the mass of a doubly charged Higgs boson only coupling to left-handed leptons varies from 770 to 870 GeV (850 GeV expected) for $$B(H^{\pm \pm }\rightarrow \ell ^{\pm }\ell ^{\pm })=100\%$$
and both the expected and observed mass limits are above 450 GeV for $$B(H^{\pm \pm }\rightarrow \ell ^{\pm }\ell ^{\pm })=10\%$$
and any combination of partial branching ratios.
165 citations
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TL;DR: A search for supersymmetric partners of quarks and gluons in final states containing hadronic jets and missing transverse momentum, but no electrons or muons, is presented in this article.
Abstract: A search for the supersymmetric partners of quarks and gluons (squarks and gluinos) in final states containing hadronic jets and missing transverse momentum, but no electrons or muons, is presented ...
149 citations
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TL;DR: In this paper, a search for heavy resonances decaying into a pair of bosons leading to the final states, where $$\ell $$¯¯ stands for either an electron or a muon, is presented.
Abstract: A search for heavy resonances decaying into a pair of $$Z$$
bosons leading to $$\ell ^+\ell ^-\ell ^+\ell ^-$$
and $$\ell ^+\ell ^-
u \bar{
u }$$
final states, where $$\ell $$
stands for either an electron or a muon, is presented. The search uses proton–proton collision data at a centre-of-mass energy of 13
$$\text {TeV}$$
corresponding to an integrated luminosity of 36.1
$$\hbox {fb}^{-1}$$
collected with the ATLAS detector during 2015 and 2016 at the Large Hadron Collider. Different mass ranges for the hypothetical resonances are considered, depending on the final state and model. The different ranges span between 200 and 2000
$$\text {GeV}$$
. The results are interpreted as upper limits on the production cross section of a spin-0 or spin-2 resonance. The upper limits for the spin-0 resonance are translated to exclusion contours in the context of Type-I and Type-II two-Higgs-doublet models, while those for the spin-2 resonance are used to constrain the Randall–Sundrum model with an extra dimension giving rise to spin-2 graviton excitations.
103 citations
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TL;DR: In this article, a search for neutral heavy resonances was performed in the WW -> e nu mu nu decay channel using collision data corresponding to an integrated luminosity of 36.1 fb(-1).
Abstract: A search for neutral heavy resonances is performed in the WW -> e nu mu nu decay channel using pp collision data corresponding to an integrated luminosity of 36.1 fb(-1), collected at a centre-o ...
100 citations
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TL;DR: In this paper, the authors search for heavy resonances decaying into ZZ or ZW using data from proton-proton collisions at a center-of-mass energy of root s - 13 TeV.
Abstract: This paper reports searches for heavy resonances decaying into ZZ or ZW using data from proton-proton collisions at a centre-of-mass energy of root s - 13 TeV. The data, corresponding to an integra ...
98 citations
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TL;DR: A search for weakly interacting massive dark-matter particles produced in association with bottom or top quarks is presented and limits on the production cross-section of 300 times the predicted rate for mediators with masses between 10 and 50GeV are set.
Abstract: A search for weakly interacting massive dark matter particles produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and missing transverse ...
92 citations
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TL;DR: This Letter documents a measurement of the first jet substructure quantity at a hadron collider to be calculated at next-to-next- to-leading-logarithm accuracy.
Abstract: Jet substructure observables have significantly extended the search program for physics beyond the standard model at the Large Hadron Collider. The state-of-the-art tools have been motivated by the ...
87 citations
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TL;DR: In this article, differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and t (t) over bar system kinematic observables using proton-proton collis...
Abstract: Measurements are made of differential cross-sections of highly boosted pair-produced top quarks as a function of top-quark and t (t) over bar system kinematic observables using proton-proton collis ...
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TL;DR: In this paper, measurements of ZZ production in the l(+)l(-)l'l'(+) l'(-) channel in proton-proton collisions at 13 TeV center-of-mass energy at the Large Hadron Collider are presented.
Abstract: Measurements of ZZ production in the l(+)l(-)l'(+)l'(-) channel in proton-proton collisions at 13 TeV center-of-mass energy at the Large Hadron Collider are presented. The data correspond to 36.1 f ...
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TL;DR: A search for massive coloured resonances which are pair-produced and decay into two jets is presented, interpreted in a SUSY simplified model where the lightest supersymmetric particle is the top squark, which decays promptly into two quarks through R-parity-violating couplings.
Abstract: A search for massive coloured resonances which are pair-produced and decay into two jets is presented. The analysis uses 36.7 fb(-1) of root s = 13 TeV pp collision data recorded by the ATLAS exper ...
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TL;DR: It is found that the correlation between the harmonic flow coefficients of charged particles in the pseudorapidity range measured in two separated η intervals does not factorise into the product of single-particle coefficients, and this breaking of factorisation, or flow decorrelation, increases linearly with the \eta $$η separation between the intervals.
Abstract: Measurements of longitudinal flow correlations are presented for charged particles in the pseudorapidity range vertical bar eta vertical bar < 2.4 using 7 mu b(-1) and 470 mu b(-1) of Pb+Pb coll ...
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TL;DR: A search for new heavy W bosons decaying to an electron or muon and a neutrino using proton–proton collision data at a centre-of-mass energy of 13 TeV finds no excess of events above the Standard Model prediction.
Abstract: The results of a search for new heavy $$W^\prime $$
bosons decaying to an electron or muon and a neutrino using proton–proton collision data at a centre-of-mass energy of $$\sqrt{s}~=~13$$
TeV are presented. The dataset was collected in 2015 and 2016 by the ATLAS experiment at the Large Hadron Collider and corresponds to an integrated luminosity of 36.1
$$\text{ fb }^{-1}$$
. As no excess of events above the Standard Model prediction is observed, the results are used to set upper limits on the $$W^\prime $$
boson cross-section times branching ratio to an electron or muon and a neutrino as a function of the $$W^\prime $$
mass. Assuming a $$W^\prime $$
boson with the same couplings as the Standard Model W boson, $$W^\prime $$
masses below 5.1 TeV are excluded at the 95% confidence level.
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TL;DR: In this paper, results from a search for supersymmetry in events with four or more charged leptons (electrons, muons, and taus) are presented using a data sample corresponding to 36.1 fb-1 of proton-proton collisions delivered by the Large Hadron Collider at s=13 TeV and recorded by the ATLAS detector.
Abstract: Results from a search for supersymmetry in events with four or more charged leptons (electrons, muons and taus) are presented. The analysis uses a data sample corresponding to 36.1 fb-1 of proton-proton collisions delivered by the Large Hadron Collider at s=13 TeV and recorded by the ATLAS detector. Four-lepton signal regions with up to two hadronically decaying taus are designed to target a range of supersymmetric scenarios that can be either enriched in or depleted of events involving the production and decay of a Z boson. Data yields are consistent with Standard Model expectations and results are used to set upper limits on the event yields from processes beyond the Standard Model. Exclusion limits are set at the 95% confidence level in simplified models of general gauge mediated supersymmetry, where Higgsino masses are excluded up to 295 GeV. In R-parity-violating simplified models with decays of the lightest supersymmetric particle to charged leptons, lower limits of 1.46, 1.06, and 2.25 TeV are placed on wino, slepton and gluino masses, respectively. © 2018 CERN.
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TL;DR: In this paper, it has been shown that Figure 30 shows the 68% and 99% confidence-level contours for the W boson and top quark mass measurements, instead of the 66% and 95% confidence level contours, as stated in the legend.
Abstract: It has been found that Figure 30 shows the 68% and 99% confidence-level contours for the W boson and top quark mass measurements, instead of the 68% and 95% confidence-level contours, as stated in the legend.
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TL;DR: Results are interpreted using simplified models, and exclude gluinos and squarks with masses as large as 1.85 and 1.3 $$\text {Te}\text {V}$$Te at 95% confidence level, respectively.
Abstract: A search for new phenomena in final states containing an e(+)e(-) or m(+)m(-) pair, jets, and large missing transverse momentum is presented. This analysis makes use of proton-proton collision data ...
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TL;DR: In this article, a search for the production of new heavy resonances decaying into a Higgs boson and a photon using proton-proton collision data at the LHC is presented.
Abstract: This Letter presents a search for the production of new heavy resonances decaying into a Higgs boson and a photon using proton-proton collision data at
√
s
=
13
TeV
collected by the ATLAS detector at the LHC. The data correspond to an integrated luminosity of
139
fb
−
1
. The analysis is performed by reconstructing hadronically decaying Higgs boson
(
H
→
b
¯
b
)
candidates as single large-radius jets. A novel algorithm using information about the jet constituents in the center-of-mass frame of the jet is implemented to identify the two
b
quarks in the single jet. No significant excess of events is observed above the expected background. Upper limits are set on the production cross-section times branching fraction for narrow spin-1 resonances decaying into a Higgs boson and a photon in the resonance mass range from 0.7 to 4 TeV, cross-section times branching fractions are excluded between 11.6 fb and 0.11 fb at a 95% confidence level.
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TL;DR: A search for high-mass resonances decaying to τν using proton-proton collisions at sqrt[s]=13 TeV produced by the Large Hadron Collider is presented and model-independent upper limits are set on the visible τν production cross section.
Abstract: A search for high-mass resonances decaying to τν using proton-proton collisions at sqrt[s]=13 TeV produced by the Large Hadron Collider is presented. Only τ-lepton decays with hadrons in the final state are considered. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 36.1 fb^{-1}. No statistically significant excess above the standard model expectation is observed; model-independent upper limits are set on the visible τν production cross section. Heavy W^{'} bosons with masses less than 3.7 TeV in the sequential standard model and masses less than 2.2-3.8 TeV depending on the coupling in the nonuniversal G(221) model are excluded at the 95% credibility level.
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TL;DR: In this paper, the authors presented measurements of differential cross sections of top quark pair production in association with jets by the ATLAS experiment at the LHC and performed as functions of the top-quark transverse momentum.
Abstract: Measurements of differential cross sections of top quark pair production in
association with jets by the ATLAS experiment at the LHC are presented. The measurements
are performed as functions of the top quark transverse momentum, the transverse
momentum of the top quark-antitop quark system and the out-of-plane transverse momentum
using data from pp collisions at √
s = 13 TeV collected by the ATLAS detector at the
LHC in 2015 and corresponding to an integrated luminosity of 3.2 fb−1
. The top quark pair
events are selected in the lepton (electron or muon) + jets channel. The measured cross
sections, which are compared to several predictions, allow a detailed study of top quark
production.
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TL;DR: In this paper, a search for direct pair production of top squarks in final states with two tau leptons, b-jets, and missing transverse momentum is presented.
Abstract: A search for direct pair production of top squarks in final states with two tau leptons, b-jets, and missing transverse momentum is presented. The analysis is based on proton-proton collision data ...
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TL;DR: In this article, the measurement of differential cross sections of isolated prompt photons produced in association with a b-jet or a c-jet was presented, which provided sensitivity to the heavy-f...
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TL;DR: The decay width of the top quark is measured using a template fit to distributions of kinematic observables associated with the hadronically and semileptonically decaying top quarks and is consistent with the prediction of the Standard Model.
Abstract: This paper presents a direct measurement of the decay width of the top quark using t (t) over bar events in the lepton+jets final state. The data sample was collected by the ATLAS detector at the L ...
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TL;DR: In this paper, a search was conducted for new resonances decaying into a W or Z boson and a 125 GeV Higgs boson in the νν¯ bb¯, l±νbb¯, and l+l−bb¯ final states, where l± = e± or μ±.
Abstract: A search is conducted for new resonances decaying into a W or Z boson and a 125 GeV Higgs boson in the νν¯ bb¯ , l±νbb¯ , and l+l−bb¯ final states, where l± = e± or μ±, in pp collisions at s=13 TeV ...
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TL;DR: In this paper, it was shown that weighted angular moments derived from jet constituents encode the color connections between partons that seed the jets. But the results were limited to two measurements of two suc...
Abstract: Previous studies have shown that weighted angular moments derived from jet constituents encode the colour connections between partons that seed the jets. This paper presents measurements of two suc ...
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TL;DR: In this paper, the authors used data from the ATLAS detector at the LHC to measure the lepton-proton collision data at a center-of-mass energy of 8 TeV with a precision of 5.7%.
Abstract: The inclusive and fiducial $t\bar{t}$ production cross-sections are measured in the lepton+jets channel using $20.2~\hbox {fb}^{-1}$ of proton–proton collision data at a centre-of-mass energy of 8 TeV recorded with the ATLAS detector at the LHC. Major systematic uncertainties due to the modelling of the jet energy scale and b-tagging efficiency are constrained by separating selected events into three disjoint regions. In order to reduce systematic uncertainties in the most important background, the $W \text {+\,jets}$ process is modelled using $Z$ + jets events in a data-driven approach. The inclusive $t\bar{t}$ cross-section is measured with a precision of 5.7% to be $\sigma _{\text {inc}}(t\bar{t}) = 248.3 \pm 0.7 \, ({\mathrm {stat.}}) \pm 13.4 \, ({\mathrm {syst.}}) \pm 4.7 \, ({\mathrm {lumi.}})~\text {pb}$ , assuming a top-quark mass of 172.5 GeV. The result is in agreement with the Standard Model prediction. The cross-section is also measured in a phase space close to that of the selected data. The fiducial cross-section is $\sigma _{\text {fid}}(t\bar{t}) = 48.8 \pm 0.1 \, ({\mathrm {stat.}}) \pm 2.0 \, ({\mathrm {syst.}}) \pm 0.9 \, ({\mathrm {lumi.}})~\text {pb}$ with a precision of 4.5%.