Dezso Horváth

Publications (2)36.28 Total impact

• Article: Two-photon laser spectroscopy of antiprotonic helium and the antiproton-to-electron mass ratio.

  Masaki Hori, Anna Sótér, Daniel Barna, Andreas Dax, Ryugo Hayano, Susanne Friedreich, Bertalan Juhász, Thomas Pask, Eberhard Widmann, Dezso Horváth, Luca Venturelli, Nicola Zurlo
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  ABSTRACT: Physical laws are believed to be invariant under the combined transformations of charge, parity and time reversal (CPT symmetry). This implies that an antimatter particle has exactly the same mass and absolute value of charge as its particle counterpart. Metastable antiprotonic helium (pHe(+)) is a three-body atom consisting of a normal helium nucleus, an electron in its ground state and an antiproton (p) occupying a Rydberg state with high principal and angular momentum quantum numbers, respectively n and l, such that n ≈ l + 1 ≈ 38. These atoms are amenable to precision laser spectroscopy, the results of which can in principle be used to determine the antiproton-to-electron mass ratio and to constrain the equality between the antiproton and proton charges and masses. Here we report two-photon spectroscopy of antiprotonic helium, in which p(3)He(+) and p(4)He(+) isotopes are irradiated by two counter-propagating laser beams. This excites nonlinear, two-photon transitions of the antiproton of the type (n, l) → (n - 2, l - 2) at deep-ultraviolet wavelengths (λ = 139.8, 193.0 and 197.0 nm), which partly cancel the Doppler broadening of the laser resonance caused by the thermal motion of the atoms. The resulting narrow spectral lines allowed us to measure three transition frequencies with fractional precisions of 2.3-5 parts in 10(9). By comparing the results with three-body quantum electrodynamics calculations, we derived an antiproton-to-electron mass ratio of 1,836.1526736(23), where the parenthetical error represents one standard deviation. This agrees with the proton-to-electron value known to a similar precision.
  Nature 07/2011; 475(7357):484-8. · 36.28 Impact Factor
• Article: A Standard Modell ellenőrzése elektron-pozitron és proton-proton ütközésekben = Test of the Standard Model in electron-positron and proton-proton collisions

  Csaba Hajdu, Beatrix Dienes, Dezso Horváth, Péter Igó Kemenes, Bertalan Juhász, Zoltán Trócsányi, Balázs Ujvári
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  ABSTRACT: A pályázat támogatásával csoportunk befejezte a CERN LEP gyorsítójának OPAL kísérletében korábban megkezdett munkáját, majd csatlakozott a rövidesen induló LHC CMS kísérletéhez. Az OPAL adatait analizálva egyebek között a töltött Higgs bozonokra adtunk alsó tömeghatárt, illetve a foton-foton ütközésekben történő hadronképződést vizsgáltuk. A CMS kísérletben a szuperszimmetrikus részecskéket kereső munkacsoport tevékenységébe kapcsolódtunk be, továbbá a kísérlet elosztott számítógépes hátterének (LHC Grid) magyarországi részét telepítettük és teszteltük. Jelenleg a CMS ún. T2 szintű számítási és adattárolási kapacitásának kb. 2%-át biztosítjuk, és az együttműködés többi résztvevőjével közösen folytatjuk a felkészülést az LHC indulásakor érkező adatok feldolgozására. | With this grant our group concluded its ongoing work in the OPAL experiment at CERN's LEP accelarator, and joined the CMS experiment of the starting LHC. Analysing OPAL data we gave, among others, a lower mass limit for charged Higgs bosons, and investigated hadron production in photon-photon collisions. In the CMS experiment we joined the group searching for supersymmetric particles, and we installed and tested the Hungarian part of the experiment's distributed computing infrastructure (LHC Grid). At the moment we cover about 2% of the T2 level CMS computing and storage capacity, and along with other participants of the collaboration we are continuing the preparations for handling the data that will arrive after the LHC startup.