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1.

001-es BibID:BIBFORM113139
035-os BibID:(cikkazonosító)168103 (WoS)001020805400001 (Scopus)85147540993
Első szerző:Abbiendi, G.
Cím:The Analytical Method algorithm for trigger primitives generation at the LHC Drift Tubes detector / G. Abbiendi, J. Alcaraz Maestre, A. Álvarez Fernández, B. Ujvari, G. Zilizi
Dátum:2023
ISSN:0168-9002
Megjegyzések:The Compact Muon Solenoid (CMS) experiment prepares its Phase-2 upgrade for the high-luminosity era of the LHC operation (HL-LHC). Due to the increase of occupancy, trigger latency and rates, the full electronics of the CMS Drift Tube (DT) chambers will need to be replaced. In the new design, the time bin for the digitization of the chamber signals will be of around 1 ns, and the totality of the signals will be forwarded asynchronously to the service cavern at full resolution. The new backend system will be in charge of building the trigger primitives of each chamber. These trigger primitives contain the information at chamber level about the muon candidates position, direction, and collision time, and are used as input in the L1 CMS trigger. The added functionalities will improve the robustness of the system against ageing. An algorithm based on analytical solutions for reconstructing the DT trigger primitives, called Analytical Method, has been implemented both as a software C++ emulator and in firmware. Its performance has been estimated using the software emulator with simulated and real data samples, and through hardware implementation tests. Measured efficiencies are 96 to 98% for all qualities and time and spatial resolutions are close to the ultimate performance of the DT chambers. A prototype chain of the HL-LHC electronics using the Analytical Method for trigger primitive generation has been installed during Long Shutdown 2 of the LHC and operated in CMS cosmic data taking campaigns in 2020 and 2021. Results from this validation step, the so-called Slice Test, are presented.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Nuclear Instruments & Methods In Physics Research Section A-Accelerators Spectrometers Detectors And Associated Equipment. - 1049 (2023), p. 1-8. -
További szerzők:Alcaraz Maestre, J. Álvarez Fernández, A. Ujvári Balázs (1977-) (fizikus) Zilizi Gyula (1965-) (fizikus)
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2.

001-es BibID:BIBFORM023411
Első szerző:Abbiendi, G.
Cím:Search for invisibly decaying Higgs bosons in e+e->Z0h0 production at s=183-209 GeV / G. Abbiendi on behalf of The OPAL Collaboration
Dátum:2010
ISSN:0370-2693
Megjegyzések:A search is performed for Higgs bosons decaying into invisible final states, produced in association with a Zo boson in e+e- collisions at energies between 183 and 209 GeV. The search is based on data samples collected by the OPAL detector at LEP corresponding to an integrated luminosity of about 660 pb-1. The analysis aims to select events containing the hadronic decay products of the Zo boson and large missing momentum, as expected from Higgs boson decay into a pair of stable weakly interacting neutral particles, such as the lightest neutralino in the Minimal Supersymmetric Standard Model. The same analysis is applied to a search for nearly invisible Higgs boson cascade decays into stable weakly interacting neutral particles. No excess over the expected background from Standard Model processes is observed. Limits on the production of invisibly decaying Higgs bosons produced in association with a Zo boson are derived. Assuming a branching ratio BR(ho->invisible)=1, a lower limit of 108.2 GeV is placed on the Higgs boson mass at the 95% confidence level. Limits on the production of nearly invisibly decaying Higgs bosons are also obtained.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Physics Letters B. - 682 : 4-5 (2010), p. 381-390. -
További szerzők:Ujvári Balázs (1977-) (fizikus) Dienes Beatrix (1972-) (élettanász, molekuláris biológus) Krasznahorkay Attila (Jr.) Trócsányi Zoltán (1961-) (fizikus) Vértesi Róbert The OPAL Collaboration
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3.

001-es BibID:BIBFORM023413
Első szerző:Abbiendi, G.
Cím:Inclusive jet production in photon-photon collisions at sqrt(see) from 189 to 209 GeV / The OPAL Collaboration
Dátum:2008
ISSN:0370-2693
Megjegyzések:nclusive jet production (e+e- -> e+e- +jet+X) is studied in collisions of quasi-real photons radiated by the LEP beams at e+e- centre-of-mass energies sqrt see from 189 to 209 GeV. Jets are reconstructed using the kp jet algorithm. The inclusive differential cross-section is measured as a function of the jet transverse momentum, ptjet, in the range 5 <ptjet < 40 GeV for pseudo-rapidities, etaj, in the range -1.5 < etaj < 1.5. The results are compared to predictions of perturbative QCD in next-to-leading order in the strong coupling constant.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Physics Letters B. - 658 : 5 (2008), p. 185-192. -
További szerzők:Trócsányi Zoltán (1961-) (fizikus) Ujvári Balázs (1977-) (fizikus) Dienes Beatrix (1972-) (élettanász, molekuláris biológus) The OPAL Collaboration
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4.

001-es BibID:BIBFORM023415
Első szerző:Abbiendi, G.
Cím:Inclusive production of charged hadrons in photon-photon collisions / G. Abbiendi on behalf of The OPAL Collaboration
Dátum:2007
ISSN:0370-2693
Megjegyzések:The inclusive production of charged hadrons in the collisions of quasi-real photons e+e- -> e+e- +X has been measured using the OPAL detector at LEP. The data were taken at e+e- centre-of-mass energies from 183 to 209 GeV. The differential cross-sections as a function of the transverse momentum and the pseudorapidity of the hadrons are compared to theoretical calculations of up to next-to-leading order (NLO) in the strong coupling constant alpha{s}. The data are also compared to a measurement by the L3 Collaboration, in which a large deviation from the NLO predictions is observed.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Physics Letters B. - 651 : 2-3 (2007), p. 92-101. -
További szerzők:Trócsányi Zoltán (1961-) (fizikus) Ujvári Balázs (1977-) (fizikus) Dienes Beatrix (1972-) (élettanász, molekuláris biológus) The OPAL Collaboration
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5.

001-es BibID:BIBFORM023417
035-os BibID:(WoS)000243973100004 (Scopus)36148976076
Első szerző:Abbiendi, G.
Cím:Search for invisibly decaying Higgs bosons with large decay width using the OPAL detector at LEP / G. Abbiendi on behalf of The OPAL Collaboration
Dátum:2007
ISSN:1434-6044
Megjegyzések:This paper describes a topological search for an invisibly decaying Higgs boson,H, produced via the Bjorken process (e+e- -> HZ). The analysis is based on data recorded using the OPAL detector at LEP at centre-of-mass energies from 183 to 209 GeV corresponding to a total integrated luminosity of 629pb-1. In the analysis only hadronic decays of the Z boson are considered. A scan over Higgs boson masses from 1 to 120 GeV and decay widths from 1 to 3000 GeV revealed no indication for a signal in the data. From a likelihood ratio of expected signal and Standard Model background we determine upper limits on cross-section times branching ratio to an invisible final state. For moderate Higgs boson decay widths, these range from about 0.07pb Mh = 60GeV) to 0.57pb (Mh = 114GeV). For decay widths above 200GeV the upper limits are of the order of 0.15pb. The results can be interpreted in general scenarios predicting a large invisible decay width of the Higgs boson. As an example we interpret the results in the so-called stealthy Higgs scenario. The limits from this analysis exclude a large part of the parameter range of this scenario experimentally accessible at LEP2.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:European Physical Journal C. - 49 : 2 (2007), p. 457-472. -
További szerzők:Trócsányi Zoltán (1961-) (fizikus) Ujvári Balázs (1977-) (fizikus) Dienes Beatrix (1972-) (élettanász, molekuláris biológus) The OPAL Collaboration
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6.

001-es BibID:BIBFORM023408
Első szerző:Abbiendi, G.
Cím:Search for Dirac magnetic monopoles in e+e- collisions with the OPAL detector at LEP2 / The OPAL Collaboration
Dátum:2008
ISSN:0370-2693
Megjegyzések: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 of sqrt(s)= 206.3GeV. The monopole signal was assumed to be characterized by two back-to-back particles with an anomalously high ionization energy loss de/dx in the tracking chambers. No evidence for production of monopoles was observed. Upper limits were obtained on the magnetic monopole pair-production cross-section (sigma) in the mass range 45 GeV/c^2<m_M<102 GeV/c^2. The average limit is sigma < 0.05 pb and is essentially independent of the magnetic monopole mass. The cross-section limit is derived at the 95% confidence level and is valid for spin-1/2 magnetic monopoles.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Physics Letters B. - 663 : 1-2 (2008), p. 37-42. -
További szerzők:Trócsányi Zoltán (1961-) (fizikus) Ujvári Balázs (1977-) (fizikus) Dienes Beatrix (1972-) (élettanász, molekuláris biológus) The OPAL Collaboration
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7.

001-es BibID:BIBFORM023406
035-os BibID:(WoS)000250842100002 (Scopus)36148976076
Első szerző:Abbiendi, G.
Cím:Bose-Einstein study of position-momentum correlations of charged pions in hadronic Z0 decays / G. Abbiendi on behalf of The OPAL Collaboration
Dátum:2007
ISSN:1434-6044
Megjegyzések:A study of Bose-Einstein correlations in pairs of identically charged pions produced in e+e- annihilations at the Z0 peak has been performed for the first time assuming a non-static emitting source. The results are based on the high statistics data obtained with the OPAL detector at LEP. The correlation functions have been analyzed in intervals of the average pair transverse momentum and of the pair rapidity, in order to study possible correlations between the pion production points and their momenta (position-momentum correlations). The Yano-Koonin and the Bertsch-Pratt parameterizations have been fitted to the measured correlation functions to estimate the geometrical parameters of the source as well as the velocity of the source elements with respect to the overall centre-of-mass frame. The source rapidity is found to scale approximately with the pair rapidity, and both the longitudinal and transverse source dimensions are found to decrease for increasing average pair transverse momenta.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:European Physical Journal C. - 52 : 4 (2007), p. 787-803. -
További szerzők:Trócsányi Zoltán (1961-) (fizikus) Ujvári Balázs (1977-) (fizikus) Dienes Beatrix (1972-) (élettanász, molekuláris biológus) The OPAL Collaboration
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8.

001-es BibID:BIBFORM023399
035-os BibID:(WoS)000250842100001 (Scopus)36148983425
Első szerző:Abbiendi, G.
Cím:Measurement of the e+e->W+W- cross section and W decay branching fractions at LEP / G. Abbiendi on behalf of The OPAL Collaboration
Dátum:2007
ISSN:1434-6044
Megjegyzések:From a total data sample of 701.1 pb^-1 recorded with e+e- centre-of-mass energies of sqrt = 161-209 GeV with the OPAL detector at LEP, 11693 W-pair candidate events are selected. These data are used to obtain measurements of the W-pair production cross sections at 10 different centre-of-mass energies. The ratio of the measured cross sections to the Standard Model expectation is found to be: data/SM = 1.002 +- 0.011(stat.) +- 0.007(syst.) +- 0.005(theory), where the uncertainties are statistical, experimental systematics and theory systematics respectively. The data are used to determine the W boson branching fractions, which are found to be consistent with lepton universality of the charged current interaction. Assuming lepton universality, the branching ratio to hadrons is determined to be 67.41 +- 0.37(stat.) +- 0.23(syst.)%, from which the CKM matrix element Vcs is determined to be 0.96+-0.017(stat.)+-0.012(syst.).The differential cross section as a function of the W^- production angle is measured for the qqev and qqmv final states. The results described in this paper are consistent with the expectations from the Standard Model.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:European Physical Journal C. - 52 : 4 (2007), p. 767-785. -
További szerzők:Trócsányi Zoltán (1961-) (fizikus) Ujvári Balázs (1977-) (fizikus) Dienes Beatrix (1972-) (élettanász, molekuláris biológus) The OPAL Collaboration
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9.

001-es BibID:BIBFORM005834
035-os BibID:(WoS)000251382800003 (Scopus)36749015100
Első szerző:Abbiendi, G.
Cím:Measurement of αs with radiative hadronic events / G. Abbiendi on behalf of The OPAL Collaboration
Dátum:2008
Megjegyzések:Hadronic final states with a hard isolated photon are studied using data taken at centre-of-mass energies around the mass of the Z boson with the OPAL detector at LEP. The strong coupling ?s is extracted by comparing data and QCD predictions for event shape observables at average reduced centre-of-mass energies ranging from 24 GeV to 78 GeV, and the energy dependence of ?s is studied. Our results are consistent with the running of ?s as predicted by QCD and show that within the uncertainties of our analysis event shapes in hadronic Z decays with hard and isolated photon radiation can be described by QCD at reduced centre-of-mass energies. Combining all values from different event shape observables and energies gives ?s(MZ)=0.1182?0.0015(stat.)?0.0101(syst.).
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
OPAL kísérlet
Megjelenés:The European Physical Journal C. - 53 (2008), p. 21-39. -
További szerzők:Trócsányi Zoltán (1961-) (fizikus) Ujvári Balázs (1977-) (fizikus) Dienes Beatrix (1972-) (élettanász, molekuláris biológus) The OPAL Collaboration
Internet cím:elektronikus változat
DOI
elektronikus változat
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10.

001-es BibID:BIBFORM023354
035-os BibID:(WoS)000272803600006 (Scopus)71249095579
Első szerző:The OPAL Collaboration
Cím:Sigma-antihyperon correlations in Z0 decay and investigation of the baryon production mechanism / The OPAL Collaboration, G. Abbiendi [et al.], [incl. Z. Trócsányi, J. Pálinkás, B. Ujvári, Gy. Zilizi, Zs. Szabó]
Dátum:2009
ISSN:1434-6044
Megjegyzések:Data collected around sqrt{s}=91 GeV by the OPAL experiment at the LEP e+e- collider are used to study the mechanism of baryon formation. As the signature, the fraction of Sigma-hyperons whose baryon number is compensated by the production of a Sigma-, Lambda or Xi- antihyperon is determined. The method relies entirely on quantum number correlations of the baryons, and not rapidity correlations, making it more model independent than previous studies. The diquark fragmentation model without the popcorn mechanism is strongly disfavored with a significance of 3.8 standard deviations including systematic uncertainties. It is shown that previous studies of the popcorn mechanism are not conclusive if parameter uncertainties are considered.
Tárgyszavak:Természettudományok Fizikai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:European Physical Journal C. - 64 : 4 (2009), p. 609-625. -
További szerzők:Abbiendi, G. Trócsányi Zoltán (1961-) (fizikus) Pálinkás József (1952-) (fizikus) Ujvári Balázs (1977-) (fizikus) Zilizi Gyula (1965-) (fizikus) Szabó Zsolt (1963-) (fizikus) Dienes Beatrix (1972-) (élettanász, molekuláris biológus) Horváth Dezső (1966-) (kémikus) Krasznahorkay Attila (Jr.) Vértesi Róbert
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