R. Messi

ORCID: 0000-0002-4888-8542
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About
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Research Areas
  • Particle physics theoretical and experimental studies
  • Quantum Chromodynamics and Particle Interactions
  • High-Energy Particle Collisions Research
  • Particle Detector Development and Performance
  • Dark Matter and Cosmic Phenomena
  • Radiation Detection and Scintillator Technologies
  • Particle Accelerators and Free-Electron Lasers
  • Superconducting Materials and Applications
  • Neutrino Physics Research
  • Computational Physics and Python Applications
  • Physics of Superconductivity and Magnetism
  • Atomic and Subatomic Physics Research
  • Radiation Therapy and Dosimetry
  • Black Holes and Theoretical Physics
  • Neural Networks and Applications
  • Distributed and Parallel Computing Systems
  • Astronomical Observations and Instrumentation
  • Cosmology and Gravitation Theories
  • Noncommutative and Quantum Gravity Theories
  • Radiation Effects in Electronics
  • Muon and positron interactions and applications
  • Medical Imaging Techniques and Applications
  • Nuclear Physics and Applications
  • Astrophysical Phenomena and Observations
  • CCD and CMOS Imaging Sensors

University of Rome Tor Vergata
2011-2023

Istituto Nazionale di Fisica Nucleare
1995-2023

Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
2010-2020

University of Catania
2020

Istituto Nazionale di Fisica Nucleare, Sezione di Roma I
2005-2019

Istituto Nazionale di Fisica Nucleare, Sezione di Catania
2018

Jagiellonian University
2015-2016

Institute of Physics
2015-2016

Istituto Nazionale di Fisica Nucleare, Sezione di Bari
2003-2016

University of Bari Aldo Moro
2013-2014

The performance of the LHCb Muon system and its stability across full 2010 data taking with LHC running at ps = 7 TeV energy is studied. optimization detector setting time calibration performed first collisions delivered by described. Particle rates, measured for wide range luminosities beam operation conditions experienced during run, are compared values expected from simulation. space alignment detectors, chamber efficiency, resolution cluster size evaluated. found to be as specifications...

10.1088/1748-0221/8/02/p02022 article EN Journal of Instrumentation 2013-02-27

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 light vector mediator this dark force, $\mathrm{U}$ boson, with KLOE detector at DA$\Phi$NE $\mathrm{e}^{+}\mathrm{e}^{-}$ collider. Using an integrated luminosity 1.54 fb$^{-1}$, we studied process $\mathrm{e}^{+}\mathrm{e}^{-} \to \mathrm{U}\gamma$, $\mathrm{U} \mathrm{e}^{+}\mathrm{e}^{-}$, using...

10.1016/j.physletb.2015.10.003 article EN cc-by Physics Letters B 2015-10-17

We have searched for a light vector boson U, the possible carrier of "dark force", with KLOE detector at DAΦNE e+e− collider, motivated by astrophysical evidence presence dark matter in Universe. Using collisions collected an integrated luminosity 239.3 pb−1, we look dimuon mass peak reaction e+e−→μ+μ−γ, corresponding to decay U→μ+μ−. find no U signal. set 90% CL upper limit mixing parameter squared between photon and 1.6×10−5 8.6×10−7 region 520<mU<980 MeV.

10.1016/j.physletb.2014.08.005 article EN cc-by Physics Letters B 2014-08-07

The recent interest in a light gauge boson the framework of an extra U(1) symmetry motivates searches mass range below 1 GeV. We present search for such particle, dark photon, e+e−→Uγ, U→π+π− based on 28 million e+e−→π+π−γ events collected at DAΦNE by KLOE experiment. π+ π− production initial-state radiation compensates loss sensitivity previous U→e+e−, μ+μ− due to small branching ratios ρ–ω resonance region. found no evidence signal and set limit 90% CL mixing strength between photon ε2, U...

10.1016/j.physletb.2016.04.019 article EN cc-by Physics Letters B 2016-04-11

Neutral kaon pairs produced in phi decays anti-symmetric entangled state can be exploited to search for violation of CPT symmetry and Lorentz invariance. We present an analysis the CP-violating process phi->K_S K_L->pi+pi-pi+pi- based on 1.7 fb-1 data collected by KLOE experiment at Frascati phi-factory DAFNE. The are used perform a measurement CPT-violating parameters Delta_amu neutral kaons contest Standard Model Extension framework. measured reference frame fixed stars are: Delta_ao =...

10.1016/j.physletb.2014.01.026 article EN cc-by Physics Letters B 2014-01-16

A bstract The three precision measurements of the cross section σ ( e + − → π γ(γ)) using initial state radiation by KLOE collaboration provide an important input for prediction hadronic contribution to anomalous magnetic moment muon. These are correlated both statistical and systematic uncertainties and, therefore, simultaneous use these requires covariance matrices that fully describe correlations. We present construction them determine a combined measurement γ(γ)). find, from this...

10.1007/jhep03(2018)173 article EN cc-by Journal of High Energy Physics 2018-03-01

The possibility of anisotropies in the speed light relative to limiting electrons is considered. absence sidereal variations energy Compton-edge photons at European Synchrotron Radiation Facility's GRAAL facility constrains such representing first nonthreshold collision-kinematics study Lorentz violation. When interpreted within minimal standard-model extension, this result yields two-sided limit 1.6×10−14 95% confidence level on a combination parity-violating photon and electron...

10.1103/physrevlett.104.241601 article EN Physical Review Letters 2010-06-17

Using 1.6 fb−1 of e + − → ϕ ηγ data collected with the KLOE detector at DAΦNE, Dalitz plot distribution for η π 0 decay is studied world's largest sample ∼ 4.7 · 106 events. The density parametrized as a polynomial expansion up to cubic terms in normalized dimensionless variables X and Y . experiment sensitive all charge conjugation conserving expansion, including gX 2 term. statistical uncertainty parameters improved by factor two respect earlier measurements.

10.1007/jhep05(2016)019 article EN cc-by Journal of High Energy Physics 2016-05-01

We searched for the $μ^+μ^-$ decay of a light vector gauge boson, also known as dark photon, in $e^+ e^- \to μ^+ μ^- γ_{\rm ISR}$ process by means Initial State Radiation (ISR) method. used 1.93~fb$^{-1}$ data collected KLOE experiment at DA$Φ$NE $ϕ$-factory. No structures have been observed over irreducible $μ^+ μ^-$ background. A 90\% CL limit on ratio $\varepsilon^2=α^{\prime}/α$ between coupling constant and fine structure $ 3\times 10^{-6}-2\times 10^{-7}$ has set photon mass region 519...

10.1016/j.physletb.2018.08.012 article EN cc-by Physics Letters B 2018-08-13

10.1016/j.nima.2009.06.082 article EN Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 2009-07-05

A measurement of the vector to pseudoscalar conversion decay $\phi \to \pi^0 e^+e^-$ with KLOE experiment is presented. sample $\sim 9500$ signal events was selected from a data set 1.7 fb$^{-1}$ $e^+e^-$ collisions at $\sqrt{s} \sim m_{\phi}$ collected DA$\Phi$NE collider. These were used obtain first transition form factor $| F_{\phi \pi^0}(q^2) |$ and new branching ratio decay: $\rm{BR}\,(\phi e^+e^-) = (\,1.35 \pm 0.05^{\,\,+0.05}_{\,\,-0.10}\,) \times 10 ^{-5}$. The result improves...

10.1016/j.physletb.2016.04.015 article EN cc-by Physics Letters B 2016-04-11

We have studied the vector to pseudoscalar conversion decay ϕ→ηe+e−, with η→π0π0π0, KLOE detector at DAΦNE. The data set of 1.7 fb−1 e+e− collisions s∼Mϕ contains a clear signal ∼31,000 events from which we measured value BR(ϕ→ηe+e−)=(1.075±0.007±0.038)×10−4. same sample is used determine transition form factor by fit invariant mass spectrum, obtaining bϕη=(1.28±0.10−0.08+0.09) GeV−2, that improves five precision previous measurement and in good agreement VMD expectations.

10.1016/j.physletb.2015.01.011 article EN cc-by Physics Letters B 2015-01-14

10.1016/j.nima.2013.12.033 article EN Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 2014-01-03

We have carried out a new direct search for the CP violating decay KS -&gt; 3pi0 with 1.7 fb^-1 of e+e- collisions collected by KLOE detector at phi-factory DAFNE. searched this in sample about 5.9 x 10^8 KL events tagging means interaction calorimeter and requiring six prompt photons. With respect to our previous search, analysis has been improved increasing factor four tagged more effective background rejection fake tags spurious clusters. find no candidates data simulated samples, while...

10.1016/j.physletb.2013.05.008 article EN cc-by Physics Letters B 2013-05-09
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