Dezsö Horváth
A5044784913- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Particle Detector Development and Performance
- Computational Physics and Python Applications
- Dark Matter and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Atomic and Molecular Physics
- Neutrino Physics Research
- Advanced Chemical Physics Studies
- Quantum, superfluid, helium dynamics
- Cold Atom Physics and Bose-Einstein Condensates
- Astrophysics and Cosmic Phenomena
- Medical Imaging Techniques and Applications
- Atomic and Subatomic Physics Research
- Black Holes and Theoretical Physics
- Nuclear physics research studies
- Particle Accelerators and Free-Electron Lasers
- Distributed and Parallel Computing Systems
- Spectroscopy and Quantum Chemical Studies
- Noncommutative and Quantum Gravity Theories
- Muon and positron interactions and applications
- Radiation Therapy and Dosimetry
- Radiation Detection and Scintillator Technologies
- Nuclear Physics and Applications
HUN-REN Wigner Research Centre for Physics
2016-2025
HUN-REN Institute for Nuclear Research
2011-2025
Babeș-Bolyai University
2022-2025
Institute for Particle and Nuclear Physics
2006-2024
Institute of High Energy Physics
2010-2024
University of Antwerp
2024
A. Alikhanyan National Laboratory
2022-2024
Eötvös Loránd University
2021
Hungarian Academy of Sciences
1996-2014
European Organization for Nuclear Research
2014
Exotic molecule tests fundamental symmetry Spectroscopy of exotic molecules can offer insight into physics. Hori et al. studied the transition frequencies an unusual helium atom in which one two electrons was substituted by antiproton, negatively charged antiparticle partner proton (see Perspective Ubachs). The antiprotonic cooled down to low temperatures allow be measured with high precision. extracted mass antiproton (relative electron mass) good agreement previous measurements mass. This...
We have observed the first laser-induced resonant transitions in antiprotonic helium atoms. These occur between metastable states and Auger dominated short lived states, show that anomalous longevity of antiprotons previously media results from formation high-n high-l atomic p\ifmmode\bar\else\textasciimacron\fi{}${\mathrm{He}}^{+}$. The transition with vacuum wavelength 597.259\ifmmode\pm\else\textpm\fi{}0.002 nm is tentatively assigned to (n,l)=(39,35)\ensuremath{\rightarrow}(38,34).
We review recent progress in the laser and microwave spectroscopy of antiprotonic helium atoms carried out at CERN's Antiproton Decelerator facility (AD). Laser transitions were here induced between Rydberg states (n, ℓ) (n ± 1, ℓ − 1) ∼ 40 ≲ n 1 being principal orbital angular momentum quantum numbers antiproton orbit). Successive refinements experimental techniques improved fractional precision on frequencies from 3 parts 106 to ∼1 part 108. These included a radiofrequency quadrupole...
Six laser-resonant transitions have been detected in metastable antiprotonic helium atoms produced at the CERN Antiproton Decelerator. They include UV from last states $v\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}n\ensuremath{-}\ensuremath{\ell}\ensuremath{-}1\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ and 1 cascades. Zero-density frequencies were obtained measured pressure shifts with fractional precisions between...
We have used a radio frequency quadrupole decelerator to decelerate antiprotons emerging from the CERN Antiproton Decelerator MeV- keV-scale energy, and collected five decelerated pulses in multiring trap. Some $5\ifmmode\times\else\texttimes\fi{}{10}^{6}$ were stacked this way. Cooling of trapped by simultaneously electron plasma was studied nondestructively via shifts mode frequencies. also demonstrated first step extracting 10--500 eV antiproton beam
Hadronic event shape distributions from e+e− annihilation measured by the OPAL experiment at centre-of-mass energies between 91 GeV and 209 are used to determine strong coupling α S. The results based on QCD predictions complete next-to-next-to-leading order (NNLO), NNLO calculations matched resummed next-to-leading-log-approximation terms (NNLO + NLLA). combined result all variables is while NLLA completeness of with respect missing higher contributions, studied varying renormalization...
We have performed laser spectroscopy of metastable antiprotonic helium atoms $(\overline{p}{\mathrm{He}}^{+})$ formed in media 0.2--8.0 bars at 5.8--6.3 K and observed a density dependence the resonance vacuum wavelengths for known transitions $(n,l)=(39,35)\ensuremath{\rightarrow}(38,34)$ $(37,34)\ensuremath{\rightarrow}(36,33).$ They showed linear redshifts $0.61\ifmmode\pm\else\textpm\fi{}0.01$ GHz $0.22\ifmmode\pm\else\textpm\fi{}0.02$ per 1 g/l, respectively. With shift parameters...
A search for stable and long-lived massive particles of electric charge |Q/e|=1 or fractional charges 2/3, 4/3, 5/3 is reported using data collected by the OPAL detector at LEP, centre-of-mass energies from 130 to 209 GeV. These are assumed be pair-produced in e+e− collisions not interact strongly. No evidence production these was observed. Model-independent upper limits on cross-section between 0.005 0.028 pb have been derived scalar spin-1/2 with ±1. Within framework Constrained Minimal...
Using a newly developed laser-microwave-laser resonance method, we observed pair of microwave transitions between hyperfine levels the $(n,L)=(37,35)$ state antiprotonic helium. This experiment confirms quadruplet structure arising from interaction antiproton orbital angular momentum, electron spin and as predicted by Bakalov Korobov. The measured frequencies ${\ensuremath{\nu}}_{\mathrm{H}\mathrm{F}}^{+}=12.895\text{ }96\ifmmode\pm\else\textpm\fi{}0.000\text{ }34\text{...
A search for the single production of doubly-charged Higgs bosons is performed using e+e− collision data collected by OPAL experiment at centre-of-mass energies between 189 GeV and 209 GeV. No evidence existence H±± observed. Upper limits are derived on hee, Yukawa coupling to like-signed electron pairs. 95% confidence level upper limit hee< 0.071 inferred M(H±±)<160 assuming that sum branching fractions all lepton flavour combinations 100%. Additionally, indirect constraints hee from Bhabha...
Total cross sections, angular, and mass distributions for the reaction ${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$p\ensuremath{\rightarrow}${\mathrm{\ensuremath{\pi}}}^{0}$${\mathrm{\ensuremath{\pi}}}^{0}$n have been measured ${\mathit{p}}_{\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$(lab)=7--140 MeV/c above threshold. The threshold amplitude was used to determine a value chiral-symmetry-breaking parameter, \ensuremath{\xi}, of -0.98\ifmmode\pm\else\textpm\fi{}0.52....
This letter describes a direct search for pair produced magnetic monopoles in e+e- collisions. The analysis is based on 62.7 pb^-1 of data collected with the OPAL detector at an average centre-of-mass energy sqrt(s)= 206.3GeV. monopole signal was assumed to be characterized by two back-to-back particles anomalously high ionization loss de/dx tracking chambers. No evidence production observed. Upper limits were obtained pair-production cross-section (sigma) mass range 45 GeV/c^2
The time evolution of the state populations in $v\ensuremath{\equiv}n\ensuremath{-}\ensuremath{\ell}\ensuremath{-}1=2$ and 3 metastable cascades antiprotonic helium (${\overline{p}}^{4}{\mathrm{He}}^{+}$) atoms were studied using laser spectroscopy. states $(n,\ensuremath{\ell})=(39,35)$, (40,36), (41,37) $v=3$ cascade estimated to initially contain, respectively, $(0.28\ifmmode\pm\else\textpm\fi{}0.04)%$, $(0.06\ifmmode\pm\else\textpm\fi{}0.02)%$, $(0.02\ifmmode\pm\else\textpm\fi{}0.01)%$...
The photon spectrum from ${K}^{\mathrm{\ensuremath{-}}}$ stopping in liquid hydrogen has been measured with a high-resolution (1.5% FWHM at 300 MeV) NaI(Tl) detector. branching ratios for ${K}^{\mathrm{\ensuremath{-}}}$p\ensuremath{\rightarrow}\ensuremath{\Lambda}\ensuremath{\gamma} (${E}_{\ensuremath{\gamma}}$=281.4 and ${K}^{\mathrm{\ensuremath{-}}}$p\ensuremath{\rightarrow}${\ensuremath{\Sigma}}^{0}$\ensuremath{\gamma} (${E}_{\ensuremath{\gamma}}$=219.5 MEV) were obtained. results are...
Laser resonance transitions between normally metastable states of antiprotonic helium atoms were observed making use state dependent quenching effects caused by small admixtures ${\mathrm{H}}_{2}$ molecules. By selectively shortening the lifetimes with higher principal quantum number $n$ as compared to those lower $n$, this method for first time provides access all initially populated $\overline{p}{\mathrm{He}}^{+}$ atoms. This was demonstrated observing...
Laser-induced resonant transitions in metastable antiprotonic $^{3}\mathrm{He}$ atoms have been found. The observed at wavelengths 593.388\ifmmode\pm\else\textpm\fi{}0.001 nm and 463.947\ifmmode\pm\else\textpm\fi{}0.002 respectively ascribed to the $(n, l)=(38, 34)\ensuremath{\rightarrow}(37, 33)$ (36,33)\ensuremath{\rightarrow}(35,32) transitions, showing excellent agreements 50 ppm with recent predictions of Korobov.
Non-commutative QED would lead to deviations from the Standard Model depending on a new energy scale Lambda_NC and unique direction in space defined by two angles eta xi. Here this analysis is as angle between rotation axis of earth. The predictions such theory for process e+e- -> gamma are evaluated specific orientation OPAL detector compared measurements. Distributions polar azimuthal scattering used extract limits model parameter eta. At 95% confidence level found be larger than 141 GeV...
Very weak laser resonances of unfavored transitions (n,l)\ensuremath{\rightarrow}(n+1,l-1) have been observed in metastable p-|${\mathrm{Am}}^{4}$${\mathrm{He}}^{+}$ atoms by using a pulsed antiproton beam. The wavelengths (713.578\ifmmode\pm\else\textpm\fi{}0.006 nm for l=34 and 726.095\ifmmode\pm\else\textpm\fi{}0.004 l=35), as well those the known favoured transitions, are to few ppm accounted recent variational calculation Korobov [Phys. Rev. A 54, R1749 (1996); (unpublished)] which...