
Antonio Passeri- PhD
- INFN - Istituto Nazionale di Fisica Nucleare
Antonio Passeri
- PhD
- INFN - Istituto Nazionale di Fisica Nucleare
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Introduction
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Publications
Publications (1,513)
We have measured the running of the effective QED coupling constant α(s) in the time-like region 0.6<s<0.975 GeV with the KLOE detector at DAΦNE using the Initial-State Radiation process e+e−→μ+μ−γ. It represents the first measurement of the running of α(s) in this energy region. Our results show a more than 5σ significance of the hadronic contribu...
The ATLAS measurement of the inclusive top quark pair (\(t\bar{t}\)) cross-section \(\sigma _{t\bar{t}}\) in proton–proton collisions at \(\sqrt{s}=8\) \(\,\mathrm{TeV}\) has been updated using the final 2012 luminosity calibration. The updated cross-section result is: $$\begin{aligned} \sigma _{t\bar{t}}= 242.9\pm 1.7\pm 5.5\pm 5.1\pm 4.2\,\mathrm...
A measurement of the cross section for the inclusive production of isolated prompt photons in proton-proton collisions at a centre-of-mass energy of \( \sqrt{s}=8 \) TeV is presented. The measurement covers the pseudorapidity ranges |η γ | < 1.37 and 1.56 ≤ |η γ | < 2.37 in the transverse energy range 25 < E T γ < 1500 GeV. The results are based on...
The new facility SuperKEKB will be an upgrade of the existing KEKB electron-positron asymmetric collider, with a target luminosity of . 8×1035cm-2s-1, about 40 times greater than that of KEKB. The detector will also be upgraded to cope with the higher luminosity, pile-up and occupancy. We report here on the design and development of the new pure Cs...
Using 1.6 fb−1of e+e−→ ϕ → ηγ data collected with the KLOE detector at DAΦNE, the Dalitz plot distribution for the η → π+π−π0decay is studied with the world’s largest sample of ∼ 4.7 · 106events. The Dalitz plot density is parametrized as a polynomial expansion up to cubic terms in the normalized dimensionless variables X and Y. The experiment is s...
A measurement of the vector to pseudoscalar conversion decay ϕ→π0e+e− with the KLOE experiment is presented. A sample of ∼9500 signal events was selected from a data set of 1.7 fb−1 of e+e− collisions at s∼mϕ collected at the DAΦNE e+e− collider. These events were used to perform the first measurement of the transition form factor |Fϕπ0(q2)| and a...
Prompt photon production in sNN=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...
The recent interest in a light gauge boson in the framework of an extra U(1) symmetry motivates searches in the mass range below 1 GeV. We present a search for such a particle, the dark photon, in e+e−→Uγ,U→π+π− based on 28 million e+e−→π+π−γ events collected at DAΦNE by the KLOE experiment. The π+ π− production by initial-state radiation compensat...
The paper presents studies of Bose-Einstein Correlations (BEC) for pairs of like-sign charged particles measured in the kinematic range [Formula: see text] 100 MeV and [Formula: see text] 2.5 in proton collisions at centre-of-mass energies of 0.9 and 7 TeV with the ATLAS detector at the CERN Large Hadron Collider. The integrated luminosities are ap...
The existence of a new force beyond the Standard Model is compelling because it could explain several striking astrophysical observations which fail standard interpretations. We searched for the light vector mediator of this dark force, the U boson, with the KLOE detector at the DAΦNE e + e − collider. Using an integrated luminosity of 1.54 fb −1 ,...
The existence of a new force beyond the Standard Model is compelling because
it could explain several striking astrophysical observations which fail
standard interpretations. We searched for the light vector mediator of this
dark force, the $\mathrm{U}$ boson, with the KLOE detector at the DA$\Phi$NE
$\mathrm{e}^{+}\mathrm{e}^{-}$ collider. Using a...
The inclusive jet cross-section is measured in proton-proton collisions at a centre-of-mass energy of 7 TeV using a data set corresponding to an integrated luminosity of 4.5 fb−1 collected with the ATLAS detector at the Large Hadron Collider in 2011. Jets are identified using the anti-k
t
algorithm with radius parameter values of 0.4 and 0.6. The...
Various differential cross-sections are measured in top-quark pair \( \left(t\overline{t}\right) \) events produced in proton-proton collisions at a centre-of-mass energy of \( \sqrt{s}=7 \) TeV at the LHC with the ATLAS detector. These differential cross-sections are presented in a data set corresponding to an integrated luminosity of 4.6 fb−1. Th...
The Frascati National Laboratories (LNF) are the oldest and largest research infrastructure of INFN, mainly devoted to the research in nuclear and particle physics, to the development of particle accelerators and frontier studies on new acceleration techniques. LNF is the place where the first electron-positron collisions were obtained in the early...
A measurement of spin correlation in tt[over ¯] production is presented using data collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb^{-1}. The correlation between the top and antitop quark spins is extracted from dilept...
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, wh...
The results of a search for charged Higgs bosons decaying to a tau lepton and a neutrino, H-+/- -> tau(+/-) nu, are presented. The analysis is based on 19.5 fb(-1) of proton-proton collision data at root s = 8TeV collected by the ATLAS experiment at the Large Hadron Collider. Charged Higgs bosons are searched for in events consistent with top-quark...
Simultaneous measurements of the t¯t, WþW−, and Z=γ → ττ production cross-sections using an integrated luminosity of 4.6 fb−1 of pp collisions at ffiffi s p ¼ 7 TeV collected by the ATLAS detector at the LHC are presented. Events are selected with two high transverse momentum leptons consisting of an oppositely charged electron and muon pair. The t...
Searches are performed for resonant and nonresonant Higgs boson pair production in the γγbb[over ¯] final state using 20 fb^{-1} of proton-proton collisions at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the CERN Large Hadron Collider. A 95% confidence level upper limit on the cross section times branching ratio of nonreson...
Measurements of inclusive jet production are performed in pp and Pb+Pb collisions at sqrt[s_{NN}]=2.76 TeV with the ATLAS detector at the LHC, corresponding to integrated luminosities of 4.0 and 0.14 nb^{-1}, respectively. The jets are identified with the anti-k_{t} algorithm with R=0.4, and the spectra are measured over the kinematic range of jet...
We searched for evidence of a Higgsstrahlung process in a secluded sector,
leading to a final state with a dark photon U and a dark Higgs boson h', with
the KLOE detector at DAFNE. We investigated the case of h' lighter than U, with
U decaying into a muon pair and h' producing a missing energy signature. We
found no evidence of the process and set...
In this paper we discuss the recent finalized analyses by the KLOE experiment
at DA$\Phi$NE: the CPT and Lorentz invariance test with entangled $K^0
\bar{K}^0$ pairs, and the precision measurement of the branching fraction of
the decay ${ K^+} \rightarrow \pi^+\pi^-\pi^+(\gamma)$. We also present the
status of an ongoing analysis aiming to precisel...
The Frascati National Laboratories (LNF) are the oldest and largest research infrastructure of INFN, mainly devoted to the research in nuclear and particle physics, to the development of particle accelerators and frontier studies on new acceleration techniques. LNF is the place where the first electron-positron collisions were obtained in the early...
The \( t\overline{t} \) production cross-section dependence on jet multiplicity and jet transverse momentum is reported for proton-proton collisions at a centre-of-mass energy of 7 TeV in the single-lepton channel. The data were collected with the ATLAS detector at the CERN Large Hadron Collider and comprise the full 2011 data sample corresponding...
A search for excited states of the Bc(±) meson is performed using 4.9 fb(-1) of 7 TeV and 19.2 fb(-1) of 8 TeV pp collision data collected by the ATLAS experiment at the LHC. A new state is observed through its hadronic transition to the ground state, with the latter detected in the decay Bc(±)→J/ψπ(±). The state appears in the m(Bc(±)π(+)π(-))-m(B...
Data from Z decays in DELPHI have been searched for [(B- d(o))over bar] â D<sup>star</sup>+ l(-) (ν) over bar (l) with the D<sup>star</sup>+ decaying to D(0)pi(+) and D-0 â K(-)pi(+), K(-)pi(+)pi(+)pi(- ) or K- pi(+)(pi(0)). These events are used to measure the CKM matrix element \V-cb\ and the form factor slope, rho(A1)(2): F- D<sup>star</sup...
A search is presented for the production of new heavy quarks that decay to a Z boson and a third-generation Standard Model quark. In the case of a new charge +2/3 quark (T ), the decay targeted is T → Zt, while the decay targeted for a new charge −1/3 quark (B) is B → Zb. The search is performed with a dataset corresponding to 20.3 fb−1 of pp colli...
The muon anomalous magnetic moment is one of the most precisely measured quantities in particle physics and a persistent discrepancy of about 3 σ between standard model (SM) prediction and the experimental measurement has been observed. The leading order contribution is actually the main source of uncertainty in the theoretical evaluation of the mu...
A search for scalar particles decaying via narrow resonances into two photons in the mass range 65-600 GeV is performed using 20.3 fb^{-1} of sqrt[s]=8 TeV pp collision data collected with the ATLAS detector at the Large Hadron Collider. The recently discovered Higgs boson is treated as a background. No significant evidence for an additional signal...
J Abdallah P Abreu W Adam- [...]
M Zupan
The hadronic part of the Electron Structure Function (ESF) has been measured for the first time, using e+e- data collected by the DELPHI experiment at LEP, at centre-of-mass energies sqrt(s) = 91.2-209.5 GeV. The data analysis is simpler than that of the measurement of the photon structure function. The ESF data are compared to predictions of pheno...
This Letter presents the first study of W^{±}W^{±}jj, same-electric-charge diboson production in association with two jets, using 20.3 fb^{-1} of proton-proton collision data at sqrt[s]=8 TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with two reconstructed same-charge leptons (e^{±}e^{±}, e^{±}μ^{±}, and μ^{±}μ^{±}) and tw...
This paper reports the results of a search for strong production of supersymmetric particles in 20.1 fb−1 of proton-proton collisions at a centre-of-mass energy of 8 TeV using the ATLAS detector at the LHC. The search is performed separately in events with either zero or at least one high-p T lepton (electron or muon), large missing transverse mome...
We have studied the vector to pseudoscalar conversion decay phi -> eta e+e-,
with eta -> pi0pi0pi0, with the KLOE detector at DAPHNE. The data set of 1.7
fb-1 of e+e- collisions at sqrt(s)~Mphi contains a clear conversion decay
signal of ~31,000 events from which we measured a value of BR(phi -> eta
e+e-)=(1.075+-0.007+-0.038)x10-4. The same sample...
Measurement of the absolute branching ratio of the K + → π + π − π + (γ) decay with the KLOE detector KLOE/KLOE-2 Collaboration The absolute branching ratio of the K + → π + π − π + (γ) decay, inclusive of final-state radiation, has been measured using ∼ 17 million tagged K + mesons collected with the KLOE detector at DANE, the Frascati φ-factory....
The ATLAS detector at the Large Hadron Collider is used to search for high-mass resonances decaying to dielectron or dimuon final states. Results are presented from an analysis of proton-proton (pp) collisions at a center-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb−1 in the dimuon channel. A narrow resonance with St...
An improved measurement of the mass of the Higgs boson is derived from a combined fit to the reconstructed invariant mass spectra of the decay channels H→γγ and H→ZZ∗→4ℓ. The analysis uses the pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at center-of-mass energies of 7 TeV and 8 TeV, corresponding to a...
We have searched for a light vector boson U, the possible carrier of a “dark force”, with the KLOE detector at the DAFNE e+e−collider, motivated by astrophysical evidence for the presence of dark matter in the Universe. Using e+e−collisions collected with an integrated luminosity of 239.3pb−1, we look for a dimuon mass peak in the reaction e+e−→μ+μ...
Measurements of four-lepton (4ℓ, ℓ=e,μ) production cross sections at the Z resonance in pp collisions at the LHC with the ATLAS detector are presented. For dilepton and four-lepton invariant mass regions m_{ℓ^{+}ℓ^{-}}>5 GeV and 80<m_{4ℓ}<100 GeV, the measured cross sections are 76±18(stat)±4(syst)±1.4(lumi) fb and 107±9(stat)±4(syst)±3.0(lumi) fb...
We have searched for a light vector boson $U$, the possible carrier of a
"dark force", with the KLOE detector at the DA$\Phi$NE $e^+e^-$ collider,
motivated by the astrophysical evidence for the presence of "dark matter" in
the universe. Using $e^+e^-$ collisions collected for an integrated luminosity
of $239.3$~pb$^{-1}$, we look for a dimuon mass...
We have searched for a light vector boson U, the possible carrier of a “dark force”, with the KLOE detector at the DAΦNE e+e− collider, motivated by the astrophysi- cal evidence for the presence of “dark matter” in the universe. Using e+e− collisions collected for an integrated luminosity of 239. 3 pb−1, we look for a dimuon mass peak in the reacti...
This Letter presents a search for quantum black-hole production using 20.3 fb-1 of data collected with the ATLAS detector in pp collisions at the LHC at √s = 8 TeV. The quantum black holes are assumed to decay into a final state characterized by a lepton (electron or muon) and a jet. In either channel, no event with a lepton-jet invariant mass of 3...
A search is presented for dark matter pair production in association with a W or Z boson in pp collisions representing 20.3 fb-1 of integrated luminosity at s=8 TeV using data recorded with the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet with the jet mass consistent with a W or Z boson, and with large missing transverse...
Neutral kaon pairs produced in phi decays in anti-symmetric entangled state
can be exploited to search for violation of CPT symmetry and Lorentz
invariance. We present an analysis of the CP-violating process phi->K_S
K_L->pi+pi-pi+pi- based on 1.7 fb-1 of data collected by the KLOE experiment at
the Frascati phi-factory DAFNE. The data are used to...
This Letter presents measurements of the polarization of the top quark in top-antitop quark pair events, using 4.7 fb^{-1} of proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at sqrt[s]=7 TeV. Final states containing one or two isolated leptons (electrons or muons) and jets are considered. Two measurements...
A search is made for massive long-lived highly ionising particles with the ATLAS experiment at the Large Hadron Collider, using 3.1 pb-1 of pp collision data taken at sqrt(s)=7 TeV. The signature of energy loss in the ATLAS inner detector and electromagnetic calorimeter is used. No such particles are found and limits on the production cross section...
Measurements of the variation of inclusive jet suppression as a function of relative azimuthal angle, Δφ, with respect to the elliptic event plane provide insight into the path-length dependence of jet quenching. ATLAS has measured the Δφ dependence of jet yields in 0.14 nb(-1) of √(s(NN))=2.76 TeV Pb+Pb collisions at the LHC for jet transverse mom...
The ATLAS detector at the Large Hadron Collider is used to search for excited electrons and excited muons in the channel pp → ℓℓ* → ℓℓγ, assuming that excited leptons are produced via contact interactions. The analysis is based on 13 fb−1 of pp collisions at a centre-of-mass energy of 8 TeV. No evidence for excited leptons is found, and a limit is...
In this Technical Design Report (TDR) we describe the SuperB detector that
was to be installed on the SuperB e+e- high luminosity collider. The SuperB
asymmetric collider, which was to be constructed on the Tor Vergata campus near
the INFN Frascati National Laboratory, was designed to operate both at the
Upsilon(4S) center-of-mass energy with a lum...
One of the basic motivations of the KLOE and KLOE-2 collaborations is the
test of fundamental symmetries and the search for phenomena beyond the Standard
Model via the hadronic and leptonic decays of ground-state mesons and via their
production in the fusion of virtual gamma quanta exchanged between colliding
electrons and positrons. This contribut...
A search for heavy long-lived multi-charged particles is performed using the ATLAS detector at the LHC. Data collected in 2012 at s√=8s=8 TeV from pp collisions corresponding to an integrated luminosity of 20.3 fb −1−1 are examined. Particles producing anomalously high ionisation, consistent with long-lived massive particles with electric charges f...
We have carried out a new direct search for the CP violating decay KS -> 3pi0
with 1.7 fb^-1 of e+e- collisions collected by the KLOE detector at the
phi-factory DAFNE. We have searched for this decay in a sample of about 5.9 x
10^8 KS KL events tagging the KS by means of the KL interaction in the
calorimeter and requiring six prompt photons. With...
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...
A search is performed for WH production with a light Higgs boson decaying to hidden-sector particles resulting in clusters of collimated electrons, known as electron-jets. The search is performed with 2.04 fb−1 of data collected in 2011 with the ATLAS detector at the Large Hadron Collider in proton–proton collisions at $\sqrt {s}=7\,{\mathrm { TeV}...
We have measured the ratio σ ( e + e − → π + π − γ ) / σ ( e + e − → μ + μ − γ ) , with the KLOE detector at DAΦNE for a total integrated luminosity of ∼ 240 pb − 1 . From this ratio we obtain the cross section σ ( e + e − → π + π − ) . From the cross section we determine the pion form factor | F π | 2 and the two-pion contribution to the muon anom...
The production of W bosons in association with two jets in proton–proton collisions at a centre-of-mass energy of $\sqrt {s} = 7\,{\mathrm {TeV}}$ has been analysed for the presence of double-parton interactions using data corresponding to an integrated luminosity of 36 pb−1, collected with the ATLAS detector at the Large Hadron Collider. The fract...
We present a new limit on the production of a light dark-force mediator with the KLOE detector at DAΦNE. This boson, called U, has been searched for in the decay ϕ → η U , U → e + e − , analyzing the decay η → π 0 π 0 π 0 in a data sample of 1.7 fb − 1 . No structures are observed in the e + e − invariant mass distribution over the background. This...
A search is presented for production of a heavy up-type quark ( t ′ ) together with its antiparticle, assuming a significant branching ratio for subsequent decay into a W boson and a b quark. The search is based on 4.7 fb−1 of pp collisions at s = 7 TeV recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. Data are analyzed in...
A bstract
We present a measurement of η meson production in photon-photon interactions produced by electron-positron beams colliding with $ \sqrt{s}=1 $ GeV. The measurement is done with the KLOE detector at the ϕ -factory DAΦNE with an integrated luminosity of 0.24 fb ⁻¹ . The e ⁺ e ⁻ → e ⁺ e ⁻ η cross section is measured without detecting the out...
The ATLAS experiment has observed 1995 Z boson candidates in data corresponding to 0.15 nb^{-1} of integrated luminosity obtained in the 2011 LHC Pb+Pb run at sqrt[s_{NN}]=2.76 TeV. The Z bosons are reconstructed via dielectron and dimuon decay channels, with a background contamination of less than 3%. Results from the two channels are consistent a...
We present a measurement of $\eta$ meson production in photon-photon interac-
tions produced by electron-positron beams colliding with √s = 1GeV. The measurement
is done with the KLOE detector at the φ-factory DA�NE with an integrated luminosity
of 0.24 fb−1. The e+e− → e+e−η cross section is measured without detecting the out-
going electron and p...
Results of a search for new phenomena in events with an energetic photon and large missing transverse momentum in proton-proton collisions at sqrt[s]=7 TeV are reported. Data collected by the ATLAS experiment at the LHC corresponding to an integrated luminosity of 4.6 fb^{-1} are used. Good agreement is observed between the data and the standard mo...
The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for pair-produced charged Higgs bosons in the framework of Two Higgs Doublet Models (2HDMs). The data of the four experiments have been statistically combined. The results are interpreted within the 2HDM for Type I and Type II benchmark scenarios. No statistically significant ex...
Measurements of luminosity obtained using the ATLAS detector during early running of the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV are presented. The luminosity is independently determined using several detectors and multiple algorithms, each having different acceptances, systematic uncertainties and sensitivity to background. The ratios of th...
This Letter presents a search for magnetic monopoles with the ATLAS detector at the CERN Large Hadron Collider using an integrated luminosity of 2.0 fb^{-1} of pp collisions recorded at a center-of-mass energy of sqrt[s]=7 TeV. No event is found in the signal region, leading to an upper limit on the production cross section at 95% confidence level...
A search for direct pair production of supersymmetric top squarks (t[over ˜]_{1}) is presented, assuming the t[over ˜]_{1} decays into a top quark and the lightest supersymmetric particle, χ[over ˜]_{1}^{0}, and that both top quarks decay to purely hadronic final states. A total of 16 (4) events are observed compared to a predicted standard model b...