Papers by Isidoro Ferrante
Zeitschrift f�r Physik C Particles and Fields, 1996
From 64492 selected -pair events, produced at the Z 0 resonance, the measurement of the tau decay... more From 64492 selected -pair events, produced at the Z 0 resonance, the measurement of the tau decays into hadrons from a global analysis using 1991, 1992 and 1993 ALEPH data is presented. Special emphasis is given to the reconstruction of photons and 0 's, and the removal of fake photons. A detailed study of the systematics entering the 0 reconstruction is also given. A complete and consistent set of tau hadronic branching ratios is presented for 18 exclusive modes. Most measurements are more precise than the present w orld average. The new level of precision reached allows a stringent test ofuniversality in hadronic decays, g =g = 1 : 0013 0:0095, and the rst measurement of the vector and axial-vector contributions to the non-strange hadronic decay width: R ;V = 1 : 788 0:025 and R ;A = 1 : 694 0:027. The ratio (R ;V R ;A )=(R ;V + R ;A ), equal to (2:7 1:3) %, is a measure of the importance of QCD non-perturbative contributions to the hadronic decay width.
Zeitschrift f�r Physik C Particles and Fields, 1997
Using data obtained with the ALEPH detector at the Z resonance, a measure based on transverse mom... more Using data obtained with the ALEPH detector at the Z resonance, a measure based on transverse momentum is shown to exhibit a correlation between the two halves of a hadronic event which cannot be explained by energy-momentum conservation, avour conservation, the imposition of an event axis or imperfect event reconstruction. Two possible interpretations based on existing Monte Carlo models are examined: a) ARIADNE, with the correlation forming early in the parton shower and with the transition from partons to hadrons playing only a minor part; b) JETSET, with the correlation forming at the fragmentation stage.
Classical and Quantum Gravity, 2014
The Twelfth Marcel Grossmann Meeting - On Recent Developments in Theoretical and Experimental General Relativity Astrophysics and Relativistic Field Theories - Proceedings of the MG12 Meeting on General Relativity, 2012
The Twelfth Marcel Grossmann Meeting - On Recent Developments in Theoretical and Experimental General Relativity Astrophysics and Relativistic Field Theories - Proceedings of the MG12 Meeting on General Relativity, 2012
Zeitschrift für Physik C: Particles and Fields, 1995
Physics Letters B, 1995
Using a sample of about 1.46 million hadronic Z decays collected between 1991 and 1993 with the A... more Using a sample of about 1.46 million hadronic Z decays collected between 1991 and 1993 with the ALEPH detector at LEP, the energy distribution of the B 0 and B mesons produced at the Z resonance is measured by reconstructing semileptonic decays B `D(X) or B``D + (X). The charmed mesons are reconstructed through the decay modes D 0 K + , D 0 K + + , D + K + + and D + D 0 + . The neutrino energy is estimated from the missing energy in the lepton hemisphere. Accounting for B and B production, the shape of the scaled energy distribution x (b) E for mesons containing a b quark is compared to the predictions of dierent fragmentation models. The mean value of x (b) E is found to be hx (b) E i = 0 : 715 0:007(stat) 0:013(syst):
Physics Letters B, 1995
Using about 1.5 million hadronic Z decays recorded with the aleph detector, the lifetime of the b... more Using about 1.5 million hadronic Z decays recorded with the aleph detector, the lifetime of the b baryons has been measured using two independent data samples. From a maximum likelihood t to the impact parameter distribution of leptons in 519 ` combinations containing a b baryon sample of 290 decays, the measured b baryon lifetime is
Zeitschrift für Physik C: Particles and Fields, 1996
The electroweak mixing angle is determined with high precision from measurements of the mean diff... more The electroweak mixing angle is determined with high precision from measurements of the mean difference between forward and backward hemisphere charges in hadronic decays of the Z. A data sample of 2.5 million hadronic Z decays recorded over the period 1990 to 1994 in the ALEPH detector at LEP is used. The mean charge separation between event hemispheres containing the original quark and antiquark is measured for bb and cc events in subsamples selected by their long lifetimes or using fast D * 's. The corresponding average charge separation for light quarks is measured in an inclusive sample from the anticorrelation between charges of opposite hemispheres and agrees with predictions of hadronisation models with a precision of 2%. It is shown that differences between light quark charge separations and the measured average can be determined using hadronisation models, with systematic uncertainties constrained by measurements of inclusive production of kaons, protons and Λ's. The separations are used to measure the electroweak mixing angle precisely as sin 2 θ eff w = 0.2322 ± 0.0008(exp. stat.) ±0.0007(exp. syst.) ± 0.0008(sep.). The first two errors are due to purely experimental sources whereas the third stems from uncertainties in the quark charge separations.
Physics Letters B, 1996
Quark and gluon jets with the same energy, 24 GeV, are compared in symmetric three-jet conguratio... more Quark and gluon jets with the same energy, 24 GeV, are compared in symmetric three-jet congurations from hadronic Z decays observed by the ALEPH detector. Jets are dened using the Durham algorithm. Gluon jets are identied using an anti-tag on b jets, based on either a track impact parameter method or a high transverse momentum lepton tag. The comparison of gluon and mixed avour quark jets shows that gluon jets have a softer fragmentation function, a larger angular width and a higher particle multiplicity. Evidence is also presented which shows that the corresponding dierences between gluon and heavy avour jets are signicantly smaller.
Zeitschrift für Physik C: Particles and Fields, 1996
Limits on the mass of the lightest neutralino () in the context of the MSSM have been derived fro... more Limits on the mass of the lightest neutralino () in the context of the MSSM have been derived from searches in the ALEPH experiment at LEP for supersymmetric particles. If the sneutrino is heavy ( > 70 GeV=c 2 ) then the 95% condence level lower limit on M is 12GeV=c 2 . A t smaller values of M~and M the assumption of common SUSY masses for scalars (m 0 ) and fermions (m 1=2 ) at the GUT scale, and the addition of data from the AMY experiment at TRISTAN, results in a lower limit for M of 5 GeV=c 2 . If minimal supergravity i s assumed then this limit is increased to 22GeV=c 2 .
Physics Letters B, 1997
A search for pair-production of long-lived, heavy, singly-charged particles has been performed wi... more A search for pair-production of long-lived, heavy, singly-charged particles has been performed with data collected by the ALEPH detector at a centre-of-mass energy of 172 GeV. Data at √ s = 161, 136, and 130 GeV are also included to improve the sensitivity to lower masses. No candidate is found in the data. A model-independent 95% confidence level upper limit on the production cross section at 172 GeV of 0.2-0.4 pb is derived for masses between 45 and 86 GeV/c 2 . This cross section limit implies, assuming the MSSM, a lower limit of 67 (69) GeV/c 2 on the mass of right-(left-) handed long-lived scalar taus or scalar muons and of 86 GeV/c 2 on the mass of long-lived charginos.
Physics Letters B, 1997
Two samples of exclusive semileptonic decays, 579 B 0 ! D +` `events and 261 B 0 ! D +` `events, ... more Two samples of exclusive semileptonic decays, 579 B 0 ! D +` `events and 261 B 0 ! D +` `events, are selected from approximately 3.9 million hadronic Z decays collected by the ALEPH detector at LEP. F rom the reconstructed dierential decay rate of each sample, the product of the hadronic form factor F(!) at zero recoil of the D + meson and the CKM matrix element jV cb j are measured to be F D + (1)jV cb j = (31:9 1:8 stat 1:9 syst ) 10 3 ; F D +(1)jV cb j = (27:8 6:8 stat 6:5 syst ) 10 3 :
Classical and Quantum Gravity, 2014
Advanced Virgo is the project to upgrade the Virgo interferometric detector of gravitational wave... more Advanced Virgo is the project to upgrade the Virgo interferometric detector of gravitational waves, with the aim of increasing the number of observable galaxies (and thus the detection rate) by three orders of magnitude. The project is now in an advanced construction phase and the assembly and integration will be completed by the end of 2015. Advanced Virgo will be part of a network with the two Advanced LIGO detectors in the US and GEO HF in Germany, with the goal of contributing to the early detections of gravitational waves and to opening a new observation window on the universe. In this paper we describe the main features of the Advanced Virgo detector and outline the status of the construction.
Physics Letters B, 1993
During 1989 and 1990 over 180 000 hadronic and leptonic events, corresponding to 8 pb 1 of lumino... more During 1989 and 1990 over 180 000 hadronic and leptonic events, corresponding to 8 pb 1 of luminosity, were collected by the ALEPH detector in a scan of the Z peak at the e + e collider LEP. This letter reports the results of a search in these data for particles with unexpected mass and charge by measurement o f the ionization energy loss of charged tracks in the ALEPH TPC central tracking detector. The mass limits for the pair production of fractionally charged particles and of heavy, long lived charged particles are extended to 43 GeV=c 2 at 90% condence level. If single production of a heavy particle is considered, the mass limit is extended to more than 70 GeV=c 2 .
Physics Letters B, 1992
In 160 000 hadronic Z decays recorded with the ALEPH detector at LEP, the yields of A£-and A~ ÷ c... more In 160 000 hadronic Z decays recorded with the ALEPH detector at LEP, the yields of A£-and A~ ÷ combinations have been measured. The observed excess of AJ~-over A£ + of 53 + 13 is interpreted as evidence for b baryons and their semileptonic decay. Assuming that three body decay processes such as Ab~A~ + ~-9 dominate the semileptonic decay of b baryons, this excess corresponds to a product branching ratio BR(b--,Ab) "BR(Ab-, A~ ÷ ~ -9) .BR(A¢ ÷ --,AX ) = (0.95 + 0.22 (stat.) + 0.21 (syst.) )%, where Ab and A~ + denote the bottom and charm baryons respectively.
Zeitschrift f�r Physik C Particles and Fields, 1997
A measurement of the inclusive production of 0 mesons in hadronic Z decays is presented and compa... more A measurement of the inclusive production of 0 mesons in hadronic Z decays is presented and compared to Monte Carlo model predictions. The analysis is based on approximately 2 million hadronic events recorded with the ALEPH detector at LEP at a centre-of-mass energy of p s = 9 1 : 2 GeV. Neutral pions are reconstructed using photons measured in the electromagnetic calorimeter and photons from conversion pairs. The inclusive 0 momentum spectrum is measured in the range 0:025 < x p = p=p beam < 1 t o b e 4 : 80 0:07(stat)0:31(sys). The dierential inclusive 0 cross section is also measured as a function of transverse momentum with respect to the event plane (p in T and p out T ).
Abstract. The present status of the VIRGO antenna, with special care of the noise limit, is prese... more Abstract. The present status of the VIRGO antenna, with special care of the noise limit, is presented. The VIRGO project (a French-Italian collaboration) has been approved in 1993 and it is now in the construction phase. The end of the commissioning phase is foreseen within 2001.
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Papers by Isidoro Ferrante