Eleni Petrakou

Eleni Petrakou

About

500
Publications
1,483,239
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36,275
Citations
Introduction
Experimental particle physicist turned freelancer. Previous work in axion searches and collider physics. Currently spending more time on astrophysics and data analysis.
Additional affiliations
March 2015 - February 2017
Institute for Basic Science
Position
  • Research Associate
October 2011 - October 2014
National Taiwan University
Position
  • Research Associate
February 2006 - September 2011
National Center for Scientific Research Demokritos
Position
  • PhD Student

Publications

Publications (500)
Article
Full-text available
A search for pair-produced bottom-like quarks in pp collisions at s=7 TeV is conducted with the CMS experiment at the LHC. The decay b′→tW is considered in this search. The b′b¯→tW-t¯W+ process can be identified by the distinctive signature of trileptons and same-sign dileptons. With a data sample corresponding to an integrated luminosity of 34 pb-...
Article
Full-text available
A New Boson with a Mass of 125 GeV Observed with the CMS Experiment at the Large Hadron Collider; The CMS Collaboration; The Higgs boson was postulated nearly five decades ago within the framework of the standard model of particle physics and has been the subject of numerous searches at accelerators around the world. Its discovery would verify...
Article
A phenomenological model is presented for the quantitative description of individual solar cycles' features, such as onset, intensity, evolution, in terms of the number of M and X-class solar flares. The main elements of the model are the relative ecliptic motion of the planets Jupiter and Saturn, and its synergy with a quasi-periodic component of...
Article
Full-text available
The Center for Axion and Precision Physics Research (CAPP) was founded in 2013, with the ambition of shedding light on the strong CP problem and the proposed existence of axions. Much of CAPP's effort focuses on the direct detection of dark matter candidate axions with a series of local haloscope experiments, which endeavour to expand dramatically...
Preprint
A forecast for the evolution of solar cycle 25 in terms of solar flares activity is presented. The forecast is derived from an existing phenomenological model based on the coupling of an internal solar component and a planetary component. In addition to sufficient temporal resolution, the predictions are characterized by features which both differe...
Preprint
Indications are presented for a significant connection between the relative motion of the planets and the appearance of energetic solar flares. Based on the records of the last four decades, the analysis highlights remarkable features and a lack of randomness in the data. The indications are supported further by the predictive power of a preliminar...
Article
A phenomenological model is presented for the quantitative description of individual solar cycles' features, such as onset, intensity, evolution, in terms of the number of M and X-class solar flares. The main elements of the model are the relative ecliptic motion of the planets Jupiter and Saturn, and its synergy with a quasi-periodic component of...
Article
Full-text available
Two-particle correlations in pPb collisions at a nucleon-nucleon center-of-mass energy of 5.02TeV are studied as a function of the pseudorapidity separation (Δη) of the particle pair at small relative azimuthal angle (|Δϕ|<π/3). The correlations are decomposed into a jet component that dominates the short-range correlations (|Δη|<1), and a componen...
Article
Full-text available
The cross section for coherent photoproduction accompanied by at least one neutron on one side of the interaction point and no neutron activity on the other side, , is measured with the CMS experiment in ultra-peripheral PbPb collisions at . The analysis is based on a data sample corresponding to an integrated luminosity of 159 , collected during t...
Article
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The invariance of the standard model (SM) under the CPT transformation predicts equality of particle and antiparticle masses. This prediction is tested by measuring the mass difference between the top quark and antiquark (Δmt=mt−mt‾) that are produced in pp collisions at a center-of-mass energy of 8 TeV, using events with a muon or an electron and...
Article
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This paper describes the CMS trigger system and its performance during Run 1 of the LHC. The trigger system consists of two levels designed to select events of potential physics interest from a GHz (MHz) interaction rate of proton-proton (heavy ion) collisions. The first level of the trigger is implemented in hardware, and selects events containing...
Article
This paper describes the CMS trigger system and its performance during Run 1 of the LHC. The trigger system consists of two levels designed to select events of potential physics interest from a GHz (MHz) interaction rate of proton-proton (heavy ion) collisions. The first level of the trigger is implemented in hardware, and selects events containing...
Article
Full-text available
A measurement of the top quark pair production (\(\mathrm{t}\overline{\mathrm{t}} \)) cross section in proton–proton collisions at the centre-of-mass energy of 8\(\,\text {TeV}\) is presented using data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.6\(\,\text {fb}^{-\text {1}}\). This analysis is perfor...
Article
Full-text available
A search for dark matter particles directly produced in proton-proton collisions recorded by the CMS experiment at the LHC is presented. The data correspond to an integrated luminosity of 18.8 fb−1, at a center-of-mass energy of 8 TeV. The event selection requires at least two jets and no isolated leptons. The razor variables are used to quantify t...
Article
A measurement is presented of the cross section for the electroweak production of a W boson in association with two jets in proton-proton collisions at a center-of-mass energy of 8 TeV. The data set was collected with the CMS detector and corresponds to an integrated luminosity of 19.3 fb−1 . The measured fiducial cross section for W bosons decayin...
Article
Full-text available
A search for pair production of third-generation scalar leptoquarks decaying to top quark and τ lepton pairs is presented using proton-proton collision data at a center-of-mass energy of s √ =8 s=8 TeV collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 19.7 fb−1. The search is performed using events that co...
Article
Full-text available
A measurement is presented of the cross section for the electroweak production of a W boson in association with two jets in proton-proton collisions at a center-of-mass energy of 8 TeV. The data set was collected with the CMS detector and corresponds to an integrated luminosity of 19.3 fb−1. The measured fiducial cross section for W bosons decaying...
Article
Full-text available
A direct search for lepton flavour violating decays of the Higgs boson (H) in the H→eτ and H→eμ channels is described. The data sample used in the search was collected in proton–proton collisions at s=8 TeV with the CMS detector at the LHC and corresponds to an integrated luminosity of 19.7 fb−1. No evidence is found for lepton flavour violating de...
Article
Full-text available
A measurement of the decorrelation of azimuthal angles between the two jets with the largest transverse momenta is presented for seven regions of leading jet transverse momentum up to 2.2\(\,\mathrm{TeV}\). The analysis is based on the proton-proton collision data collected with the CMS experiment at a centre-of-mass energy of 8\(\,\mathrm{TeV}\) c...
Article
Full-text available
Searches for new physics by the CMS collaboration are interpreted in the framework of the phenomenological minimal supersymmetric standard model (pMSSM). The data samples used in this study were collected at \( \sqrt{s}=7 \) and 8 TeV and have integrated luminosities of 5.0 fb−1 and 19.5 fb−1, respectively. A global Bayesian analysis is performed,...
Article
Full-text available
Measurements are reported of the normalized differential cross sections for top quark pair production with respect to four kinematic event variables: the missing transverse energy; the scalar sum of the jet transverse momentum (pT); the scalar sum of the pT of all objects in the event; and the pT of leptonically decaying W bosons from top quark dec...
Article
Full-text available
Measurements are reported of the normalized differential cross sections for top quark pair production with respect to four kinematic event variables: the missing transverse energy; the scalar sum of the jet transverse momentum (pT); the scalar sum of the pT of all objects in the event; and the pT of leptonically decaying W bosons from top quark dec...
Article
Full-text available
A search is presented for single top quark production in the s channel in proton-proton collisions with the CMS detector at the CERN LHC in decay modes of the top quark containing a muon or an electron in the final state. The signal is extracted through a maximum-likelihood fit to the distribution of a multivariate discriminant defined using booste...
Article
Full-text available
A search is presented for the Higgs boson off-shell production in gluon fusion and vector boson fusion processes with the Higgs boson decaying into a W+W− pair and the W bosons decaying leptonically. The data observed in this analysis are used to constrain the Higgs boson total decay width. The analysis is based on the data collected by the CMS exp...
Article
Full-text available
The polarizations of the , , and mesons are measured as a function of the charged particle multiplicity in proton-proton collisions at . The measurements are performed with a dimuon data sample collected in 2011 by the CMS experiment, corresponding to an integrated luminosity of 4.9 fb−1. The results are extracted from the dimuon decay angular dist...
Article
The inclusive cross section for top quark pair production is measured in proton-proton collisions at \( \sqrt{s}=7 \) and 8 TeV, corresponding to 5.0 and 19.7 fb−1, respectively, with the CMS experiment at the LHC. The cross sections are measured in the electron-muon channel using a binned likelihood fit to multi-differential final state distributi...
Article
Full-text available
Results are reported from a search for the pair production of top squarks, the supersymmetric partners of top quarks, in final states with jets and missing transverse momentum. The data sample used in this search was collected by the CMS detector and corresponds to an integrated luminosity of 18.9\(\,\text {fb}^\text {-1}\) of proton-proton collisi...
Article
Full-text available
The differential cross section and charge asymmetry for inclusive \(\mathrm {p}\mathrm {p}\rightarrow \mathrm {W}^{\pm }+X \rightarrow \mu ^{\pm }\nu +X\) production at \(\sqrt{s}=8\,\mathrm{TeV} \) are measured as a function of muon pseudorapidity. The data sample corresponds to an integrated luminosity of 18.8\(\,\text {fb}^{-1}\) recorded with t...
Article
Full-text available
A search for exclusive or quasi-exclusive γγ → W+W− production, via pp → p(*)W+W−p(*) → p(*)μ±e∓p(*) at \( \sqrt{s}=8 \) TeV, is reported using data corresponding to an integrated luminosity of 19.7 fb−1. Events are selected by requiring the presence of an electron-muon pair with large transverse momentum pT(μ±e∓) > 30 GeV, and no associated charge...
Article
Full-text available
The decorrelation in the azimuthal angle between the most forward and the most backward jets (Mueller-Navelet jets) is measured in data collected in pp collisions with the CMS detector at the LHC at \( \sqrt{s}=7 \) TeV. The measurement is presented in the form of distributions of azimuthal-angle differences, Δϕ, between the Mueller-Navelet jets, t...
Article
Full-text available
The consistency of the spin correlation strength in top quark pair production with the standard model (SM) prediction is tested in the muon+jets final state. The events are selected from pp collisions, collected by the CMS detector, at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb−1. The data are compared wi...
Article
Full-text available
A search is reported for a light pseudoscalar Higgs boson decaying to a pair of τ leptons, produced in association with a bb pair, in the context of two-Higgs-doublet models. The results are based on pp collision data at a centre-of-mass energy of 8 TeV collected by the CMS experiment at the LHC and corresponding to an integrated luminosity of 19.7...
Article
Full-text available
An inclusive measurement of the Zγ→νν‾γ production cross section in pp collisions at s=8TeV is presented, using data corresponding to an integrated luminosity of 19.6 fb−1 collected with the CMS detector at the LHC. This measurement is based on the observation of events with large missing energy and with a single photon with transverse momentum abo...
Article
Full-text available
The charge asymmetry in tt‾ events is measured using dilepton final states produced in pp collisions at the LHC at s=8TeV. The data sample, collected with the CMS detector, corresponds to an integrated luminosity of 19.5fb−1. The measurements are performed using events with two oppositely charged leptons (electrons or muons) and two or more jets, w...
Article
Full-text available
Inclusive jet production in pPb collisions at a nucleon–nucleon (NN) center-of-mass energy of \(\sqrt{s_{_\mathrm {NN}}} =5.02\,\mathrm{TeV} \) is studied with the CMS detector at the LHC. A data sample corresponding to an integrated luminosity of 30.1 nb\(^{-1}\) is analyzed. The jet transverse momentum spectra are studied in seven pseudorapidity...
Article
Full-text available
A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (\({\mathrm{H}}\)) in proton-proton collisions collected by the CMS experiment at the LHC at \(\sqrt{s}=8\,\text {TeV} \). The data correspond to an integrated luminosity of 19.7\(\,\text {fb}^{-1}\). The search considers \({\mathrm{H}} {\mathrm{H}} \) resonance...
Article
Full-text available
Jet multiplicity distributions in top quark pair (t t ¯) events are measured in pp collisions at a centre-of-mass energy of 8 TeV with the CMS detector at the LHC using a data set corresponding to an integrated luminosity of 19.7fb-1. The measurement is performed in the dilepton decay channels (e +e -, μ+μ-, and e ±μ∓). The absolute and normalized...
Article
Results are reported from a search for the top squark \( {\tilde{\mathrm{t}}}_1 \), the lighter of the two supersymmetric partners of the top quark. The data sample corresponds to 19.7 fb−1 of proton-proton collisions at \( \sqrt{s}=8 \) TeV collected with the CMS detector at the LHC. The search targets \( {\tilde{\mathrm{t}}}_1\to \mathrm{b}{\tild...
Article
Full-text available
A measurement of the W boson pair production cross section in proton-proton collisions at \(\sqrt{s} = 8\) TeV is presented. The data collected with the CMS detector at the LHC correspond to an integrated luminosity of 19.4\(\,\text {fb}^\text {-1}\). The \({{\mathrm{W} }^{+} }\mathrm{W}^{-} \) candidates are selected from events with two charged l...
Article
Full-text available
This paper presents the search for the production of a Higgs boson in association with a single top quark (tHq), using data collected in proton-proton collisions at a center-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb−1 . The search exploits a variety of Higgs boson decay modes resulting in final states with photons...
Article
Full-text available
The results of a search for a supersymmetric partner of the top quark (top squark), pair-produced in proton–proton collisions at s=8 TeV, are presented. The search, which focuses on R-parity violating, chargino-mediated decays of the top squark, is performed in final states with low missing transverse momentum, two oppositely charged electrons or m...
Article
Full-text available
The inelastic hadronic cross section in proton–lead collisions at a centre-of-mass energy per nucleon pair of 5.02 TeV is measured with the CMS detector at the LHC. The data sample, corresponding to an integrated luminosity of , has been collected with an unbiased trigger for inclusive particle production. The cross section is obtained from the mea...
Article
Full-text available
A search for the production of a heavy B quark, having electric charge -1/3 and vector couplings to W, Z, and H bosons, is carried out using proton-proton collision data recorded at the CERN LHC by the CMS experiment, corresponding to an integrated luminosity of 19.7 fb-1. The B quark is assumed to be pair produced and to decay in one of three ways...
Article
Full-text available
The t ̄ tcharge asymmetry is measured in proton–proton collisions at a centre-of-mass energy of 8TeV. The data, collected with the CMS experiment at the LHC, correspond to an integrated luminosity of 19.7 fb − 1 . Selected events contain an electron or a muon and four or more jets, where at least one jet is identified as originating from b-quark ha...
Article
Full-text available
The t ̄ tcharge asymmetry is measured in proton–proton collisions at a centre-of-mass energy of 8TeV. The data, collected with the CMS experiment at the LHC, correspond to an integrated luminosity of 19.7 fb − 1 . Selected events contain an electron or a muon and four or more jets, where at least one jet is identified as originating from b-quark ha...
Article
Full-text available
A search for anomalous pseudoscalar couplings of the Higgs boson H to electroweak vector bosons V (=W or Z) in a sample of proton-proton collision events corresponding to an integrated luminosity of 18.9 fb−1at a center-of-mass energy of 8 TeVis presented. Events consistent with the topology of associated VH production, where the Higgs boson decays...
Article
Full-text available
Results are reported from a search for supersymmetry with gauge-mediated supersymmetry breaking in electroweak production. Final states with photons and large missing transverse energy ( ETmiss) were examined. The data sample was collected in pp collisions at s=8TeV with the CMS detector at the LHC and corresponds to 7.4fb−1. The analysis focuses o...
Article
Full-text available
A search for narrow resonances decaying to an electron and a muon is presented. The eμ mass spectrum is also investigated for non-resonant contributions from the production of quantum black holes (QBHs). The analysis is performed using data corresponding to an integrated luminosity of 19.7 fb⁻¹ collected in proton-proton collisions at a centre-of-m...
Article
Full-text available
A measurement of the forward–backward asymmetry AFB of oppositely charged lepton pairs (μμ and ee) produced via Z / γ∗ boson exchange in pp collisions at √s = 8 TeV is presented. The data sample corresponds to an integrated luminosity of 19.7 fb⁻¹ collected with the CMS detector at the LHC. The measurement of AFB is performed for dilepton masses be...
Article
Full-text available
This paper presents the search for the production of a Higgs boson in association with a single top quark (tHq), using data collected in proton-proton collisions at a center-of-mass energy of 8 TeV corresponding to an integrated luminosity of 19.7 fb−1. The search exploits a variety of Higgs boson decay modes resulting in final states with photons,...
Article
Full-text available
A search is performed for a new resonance decaying into a lighter resonance and a Z boson. Two channels are studied, targeting the decay of the lighter resonance into either a pair of oppositely charged τ leptons or a pair. The Z boson is identified via its decays to electrons or muons. The search exploits data collected by the CMS experiment at a...
Article
Full-text available
A search for supersymmetry in hadronic final states with highly boosted W bosons and b jets is presented, focusing on compressed scenarios. The search is performed using proton-proton collision data at a center-of-mass energy of 8 TeV, collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 19.7 fb-1. Events contain...
Article
Full-text available
The production of Z bosons in pPb collisions at is studied by the CMS experiment via the electron and muon decay channels. The inclusive cross section is compared to pp collision predictions, and found to scale with the number of elementary nucleon-nucleon collisions. The differential cross sections as a function of the Z boson rapidity and transve...
Article
Full-text available
Results are presented from a search for supersymmetric particles in scenarios with small mass splittings. The data sample corresponds to 19.7fb−1of proton-proton collisions recorded by the CMS experiment at s=8TeV. The search targets top squark (t˜) pair production in scenarios with mass differences Δm=m(t˜)−m(χ˜10) below the W-boson mass and with...
Article
Full-text available
A search is reported for a light pseudoscalar Higgs boson decaying to a pair of τ leptons, produced in association with a pair, in the context of two-Higgs-doublet models. The results are based on pp collision data at a centre-of-mass energy of 8 TeV collected by the CMS experiment at the LHC and corresponding to an integrated luminosity of 19.7 fb...