Publications
2196 results found
Aubert B, Bona M, Boutigny D, et al., 2007, Measurement of <i>B</i> decays to φ<i>K</i>γ, PHYSICAL REVIEW D, Vol: 75, ISSN: 1550-7998
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- Citations: 3
Aubert B, Barate R, Boutigny D, et al., 2007, Measurements of Λ<sub>c</sub><SUP>+</SUP> branching fractions of Cabibbo-suppressed decay modes involving Λ and Σ<SUP>0</SUP>, PHYSICAL REVIEW D, Vol: 75, ISSN: 1550-7998
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- Citations: 6
Aubert B, Barate R, Bona M, et al., 2007, Observation of decays <i>B</i><SUP>0</SUP>→<i>D<sub>s</sub></i><SUP>(*)+</SUP>π<SUP>-</SUP> and <i>B</i><SUP>0</SUP>→<i>D<sub>s</sub></i><SUP>(*)-</SUP><i>K</i><SUP>+</SUP>, PHYSICAL REVIEW LETTERS, Vol: 98, ISSN: 0031-9007
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- Citations: 12
Aubert B, Bona M, Boutigny D, et al., 2007, Search for lepton flavor violating decays τ<SUP>±</SUP>→<i>l</i><SUP>±</SUP><i>π</i><SUP>0</SUP>,<i>l</i><SUP>±</SUP><i>η</i>,<i>l</i><SUP>±</SUP><i>η</i>′, PHYSICAL REVIEW LETTERS, Vol: 98, ISSN: 0031-9007
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- Citations: 37
Aubert B, Barate R, Bona M, et al., 2007, Observation of B-->eta'K* and evidence for B+-->eta'rho+., Phys Rev Lett, Vol: 98, ISSN: 0031-9007
We present an observation of B-->eta'K*. The data sample corresponds to 232x10(6) BB[over ] pairs collected with the BABAR detector at the PEP-II asymmetric-energy B factory at the Stanford Linear Accelerator Center. We measure the branching fractions (in units of 10(-6)) B(B(0)-->eta'K*0)=3.8+/-1.1+/-0.5 and B(B+-->eta'K*+)=4.9(1.7)(+1.9)+/-0.8, where the first error is statistical and the second systematic. A simultaneous fit results in the observation of B-->eta'K* with B(B-->eta'K*)=4.1(-0.9)(+1.0)+/-0.5. We also search for B-->eta'rho and eta'f(0)(980)(f(0)-->pi+pi-) with results and 90% confidence level upper limits B(B+-->eta'rho+)=8.7(-2.8-1.3)(+3.1+2.3) (<14), B(B(0)-->eta'rho0)<3.7, and B(B(0)-->eta'f(0)(980)(f(0)-->pi+pi-))<1.5. Charge asymmetries in the channels with significant yields are consistent with zero.
Aubert B, Barate R, Bona M, et al., 2007, Observation of <i>B</i>→η′ <i>K</i><SUP>*</SUP> and evidence for <i>B</i><SUP>+</SUP>→η′ <i>p</i><SUP>+</SUP>, PHYSICAL REVIEW LETTERS, Vol: 98, ISSN: 0031-9007
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- Citations: 6
Aubert B, Barate R, Bona M, et al., 2007, Measurement of the <i>CP</i> asymmetry and branching fraction of <i>B</i><SUP>0</SUP>→ρ<SUP>0</SUP><i>K</i><SUP>0</SUP>, PHYSICAL REVIEW LETTERS, Vol: 98, ISSN: 0031-9007
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- Citations: 9
Aubert B, Bona M, Boutigny D, et al., 2007, Vector-tensor and vector-vector decay amplitude analysis of B<SUP>0</SUP>→φ<i>K</i>*0, PHYSICAL REVIEW LETTERS, Vol: 98, ISSN: 0031-9007
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- Citations: 37
Aubert B, Barate R, Bona M, et al., 2007, Branching fraction measurement of (<i>B</i>)over-bar<SUP>0</SUP>→ <i>D</i><SUP>(*)+</SUP>π<SUP>-</SUP> and <i>B</i><SUP>-</SUP>→ <i>D</i><SUP>(*)0</SUP>π<SUP>-</SUP> and isospin analysis of (<i>B</i>)over-bar → <i>D</i><SUP>(*)</SUP>π decays, PHYSICAL REVIEW D, Vol: 75, ISSN: 2470-0010
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- Citations: 10
Aubert B, Bona M, Boutigny D, et al., 2007, Search for the reactions <i>e</i><SUP>+</SUP><i>e</i><SUP>-</SUP> → μ<SUP>+</SUP>τ<SUP>-</SUP> and <i>e</i><SUP>+</SUP><i>e</i><SUP>-</SUP>→ <i>e</i><SUP>+</SUP>τ<SUP>-</SUP>, PHYSICAL REVIEW D, Vol: 75, ISSN: 1550-7998
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- Citations: 7
Aubert B, Bona M, Boutigny D, et al., 2007, Observation of <i>CP</i> violation in <i>B</i>→<i>η/K</i><SUP>0</SUP> decays, PHYSICAL REVIEW LETTERS, Vol: 98, ISSN: 0031-9007
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- Citations: 19
Aubert B, Barate R, Bona M, et al., 2007, Observation of a charmed baryon decaying to <i>D</i><SUP>0</SUP><i>p</i> at a mass near 2.94 GeV/<i>c</i><SUP>2</SUP>, PHYSICAL REVIEW LETTERS, Vol: 98, ISSN: 0031-9007
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- Citations: 119
Aubert B, Bona M, Boutigny D, et al., 2007, Measurements of the branching fractions of B<sup>0</sup>→ K <sup>*0</sup>K<sup>+</sup>K<sup>-</sup>, B<sup>0</sup>→ K<sup>*0</sup> π+K<sup>-</sup>, B<sup>0</sup>→ K <sup>*0</sup>K+π-, and B<sup>0</sup>→ K <sup>*0</sup>π+ π-
Branching fraction measurements of charmless B0 → K *0h+1 h- 2 (h1,2 = K, π) decays are pre-sented, using a data sample of 383 million σ(4S) → BB decays collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. The results are: B(B0 → K*0K+K-) = (27.5 ± 1.3 ± 2.2) × 10-6, B(B0 → K z.ast;0+K-) = (4.6 ± 1.1 ± 0.8) × 10-6 and B(B0 → Kz.ast;0+π-) = (54.5 ± 2.9 ± 4.3) × 10-6. The first errors quoted are statistical and the second are systematic. An upper limit is set for B(B0 → Kz.ast;0+π-) < 2.2 × 10-6 at 90% confidence level. We also present measurements of CP-violating asymmetries for the observed decays.
Aubert B, Bona M, Boutigny D, et al., 2007, Search for the rare charmless hadronic decay B<sup>+</sup>→ a <sup>+</sup><inf>0</inf> π<inf>0</inf>
We present a search for B decays to a charged scalar meson a+0 and a π0 where the a+0 decays to an π meson and a π+. The analysis was performed on a data sample consisting of 383×106 BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We find no significant signal and set an upper limit on the product branching fraction B(B+ → +→ a+0 π0) × B(a+0 → ηπ+) of 1.4×10-6 at the 90% confidence level.
Aubert B, Bona M, Boutigny D, et al., 2007, Evidence for b → d γ transitions from a sum of exclusive final states in the hadronic final state mass range 1.0GeV/c<sup>2</sup> < M(X <inf>d</inf>) < 1.8GeV/c<sup>2</sup>
We present preliminary results of a search for B → Xdγ decays with a hadronic mass 1.0 GeV/c2 < M(Xd) < 1.8 GeV/c2. We consider seven final states with up to four charged pions and one neutral pion or η, which correspond to about 50% of the total Xd fragmentation in this mass range. Based on a sample of 383 million B ̄B events collected by the BaBar experiment at PEPII, we measure a partial branching fraction P7 Xd=1 B(B → Xdγ)|(1.0GeV/c2<M(Xd)<1.8GeV/c2) = (3.1±0.9+0.6 -0.5 ±0.5) · 10-6, where the uncertainties are statistical, systematic and model-dependent respectively.
Aubert B, Bona M, Boutigny D, et al., 2007, Measurement of the B<sup>0</sup>→ X-u ℓ+νℓ decays near the kinematic endpoint of the lepton spectrum and search for violation of isospin symmetry
We present the first measurement of the B0 → X-u ℓ+νℓ partial branching fraction in the endpoint region of the lepton momentum spectrum, above the threshold for B → Xcℓνℓ decays. The analysis is based on a sample of 383 million γ(4S) decays into BB pairs collected with the BABAR detector at the PEP-II e+e- storage rings. We select B0B0 events by partially reconstructing one B meson via the B0 → Dz.ast;+ℓ- ̄νℓ decays then select B0 → X- u ℓ+νℓ decays identifying a second high momentum lepton. In the momentum interval ranging from 2.3 to 2.6 GeV/c we measure the partial branching fraction πB(B0 → Xuℓν) = (1.30 ± 0.21stat ± 0.07syst) × 10-4 where the first error is statistical and the second is systematic. By comparing this measurement with the one obtained from untagged B decays we obtain R+/0 = ΔB(B0 → Xuℓν)/ ΔB(B+ → Xuℓν) = 1.18 ± 0.35stat ± 0.17syst. Using this measurement we extract a limit on the contributions from processes breaking isospin symmetry in charmless semileptonic B decays.
Aubert B, Bona M, Boutigny D, et al., 2007, Measurement of the branching fractions of exclusive B̄ → D/D <sup>*</sup>/D(<sup>*</sup>)πℓ-̄νℓ decays in events tagged by a fully reconstructed B meson
We present a measurement of the branching fractions for B → D/D */D(*)πℓ-̄νℓ decays based on 341.1 fb-1 of data collected at the γ(4S) resonance with the BABAR detector at the PEP-II e+e- storage rings. Events are tagged by fully reconstructing one of the B mesons in a hadronic decay mode. We obtain B(B- → D0ℓ-̄νℓ) = (2.33 ± 0.09 (stat.) ± 0.09 (syst.))%, B(B- → D*0ℓ-̄νℓ) = (5.83±0.15 (stat.)±0.30 (syst.))%, B(B0 → D+ℓ-̄νℓ) = (2.21±0.11 (stat.)±0.12 (syst.))%, B(B0 → D*+ℓ-̄νℓ) = (5.49 ± 0.16 (stat.) ± 0.25 (syst.))%, B(B- → D+π-ℓ-̄νℓ) = (0.42 ± 0.06 (stat.) ± 0.03 (syst.))%, B(B- → D *+π-ℓ-̄νℓ) = (0.59±0.05 (stat.)±0.04 (syst.))%, B(B0 → D*π+ℓ- ̄νℓ) = (0.43±0.08 (stat.)±0.03 (syst.))% and B(B0 → D*0π+ℓ-̄νℓ) = (0.48±0.08 (stat.)±0.04 (syst.))%.
Aubert B, Bona M, Boutigny D, et al., 2007, Time-dependent analysis of the decay B<sup>0</sup> → ρ<sup>0</sup>ρ<sup>0</sup>
We study the decay B0 → ρ0ρ0 in a sample of about 427 million γ(4S) → BB decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We find the branching fraction B = (0.84 ± 0.29 ± 0.17) × 10-6 and longitudinal polarization fraction of fL = 0.70 ± 0.14 ± 0.05, where the first uncertainty is statistical, and the second is systematic. The evidence for the B0 → ρ0ρ0signal has 3.6σ significance. We investigate the proper-time dependence of the longitudinal component in the decay and measure the CP-violating coefficients S00 L = (0.5± 0.9 ± 0.2) and C00 L = (0.4 ± 0.9 ± 0.2), corresponding to the sine and cosine terms in the time evolution of asymmetry. We study the implication of these results for penguin contributions in B → ρρ decays and for the CKM unitarity angle α.
Aubert B, Bona M, Boutigny D, et al., 2007, Time-dependent dalitz plot analysis of B<sup>0</sup> → K <sup>0</sup><inf>S</inf> π+π-
We perform a time-dependent Dalitz plot analysis of B0 → K0 S π+π- in order to extract the CP violation parameters of f0(980)K0 S and ρ0(770)K0 S and direct CP-asymmetries of Kz.ast;+(892)π-. The results are obtained from a data sample of (383 ± 3) × 106 BB decays, collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The measured values of 2βeff in B0 decays to f0(980)K0S and ρ0(770)K0 S are (89+22-20 ± 5 ±8) and (37+19 -17 ± 5 ±6), respectively, where the first quoted uncertainty is statistical, the second is systematic and the third is Dalitz plot signal model uncertainty. We measure the significance of 2βeff (f0(980)K0S) 6= 0 to be 4.3 σ. In decays to Kz.ast;(892)π we find ACP = -0.18 ± 0.10 ± 0.03 ± 0.03. The measured phase difference between the decay amplitudes of B0 → Kz.ast;+(892)π- and B0 → Kz.ast;-(892)π+ is (-164 ± 24 ± 12 ± 15). All results are preliminary.
Aubert B, Bona M, Boutigny D, et al., 2007, Measurement of the branching fraction ratios and CP asymmetries in B-→ D<sup>0</sup><inf>CP</inf> K-decays
We present a preliminary study of B- → D0(CP)π- and B- → D0(CP)K- decays, with the D0(CP)reconstructed in the CP-odd eigenstates Ksπ0, Ks, in the CP-even eigenstates K+K-, π+π-, and in the (non-CP) flavor eigenstate K±π ±. Using a sample of about 382 million γ(4S) decays into BB pairs, collected with the BABAR detector operating at the PEP-II asymmetric-energy B Factory at SLAC, we measure the ratios of the branching fractions B(B- → D0 CP±K-) + B(B+ → D0 CP±K+) [B(B- → D0K-) + B(B+ → D0K+)]/2 and the direct CP asymmetry ACP± Ξ B(B-→D0 CP±K-) - B(B+→D0 CP±K+) B(B-→D0 CP±K-) + B(B+→D0 CP±K+) . The results are: RCP- = 0.81 ± 0.10(stat) ± 0.05(syst) RCP+ = 1.07 ± 0.10(stat) ± 0.04(syst) ACP- = -0.19 ± 0.12(stat) ± 0.02(syst) ACP+ = 0.35 ± 0.09(stat) ± 0.05(syst).
Aubert B, Bona M, Boutigny D, et al., 2007, Measurement of the time-dependent CP asymmetry in B<sup>0</sup>→ K<sup>*0</sup> γ decays
We present a preliminary measurement of the time-dependent CP asymmetry in B0 → K*0 (K0Sπ 0)γ decays based on 431 × 106 γ(4S) → BB decays collected with the BABAR detector at the PEP-II asymmetric-energy e +e- collider at SLAC. In a sample containing 316±22 signal events we measure SK* = -0.08 ± 0.31 ± 0.05 and CK*γ = -0.15 ± 0.17 ± 0.03. The uncertainties are statistical and systematic, respectively.
Achenbach R, Adragna P, Aielli G, et al., 2007, The ATLAS level-1 trigger: Status of the system and experience from commissioning with cosmic ray muons, Pages: 2123-2129, ISSN: 1095-7863
The ATLAS detector at CERN's Large Hadron Collider (LHC) will be exposed to proton-proton collisions from beams crossing at 40 MHz. A three-level trigger system will select potentially interesting events in order to reduce this rate to 100-200 Hz. A trigger decision is made by the Level-1 Central Trigger Processor (CTP) reducing the incoming rate to less than 100 kHz. The Level-1 decision is based on Calorimeter information and hits in dedicated Muon Trigger detectors. The final Level-1 trigger system is currently being installed in the experiment with completion expected in autumn 2007. Cosmic ray data are regularly recorded as an increasing fraction of the trigger system comes online. We present an overview of the Level-1 trigger system architecture and report on the installation and commissioning process at the ATLAS experimental site. Emphasis is put on the integration of the CTP with the Calorimeter and Muon Trigger systems. We show results from analyses of cosmic ray data recorded in situ and verify, where possible, that the Level-1 trigger meets the requirements and will be ready for data taking. ©2007 IEEE.
Achenbach R, Andrei V, Bauss B, et al., 2007, High-density backplanes: Problems and solutions, Pages: 512-514
The backplane and crate infrastructure for the digital processors of the ATLAS Level-1 Calorimeter Trigger (L1Calo) are presented, The L1Calo system is a compact, high-performance real-time system based on a custom, monolithic 9U backplane populated almost completely with 2mm Hard Metric connectors. The high pin count and monolithic design present challenges including high insertion/extraction forces, and maintenance and repair over the lifetime of LHC. We have developed solutions for these issues, as well as providing infrastructure for power distribution and cable strain relief, while maintaining accessibility, access for testing as well as long-term maintenance and repair.
Achenbach R, Andrei V, Bauss B, et al., 2007, Production test rig for the ATLAS level-1 calorimeter trigger digital processors, Pages: 391-394
The Level-1 Calorimeter Trigger is a digital pipelined system, reducing the 40 MHz bunch-crossing rate down to 75 kHz. It consists of a Preprocessor, a Cluster Processor (CP), and a Jet/Energy-sum Processor (JEP). The CP and JEP receive digitised trigger-tower data from the Preprocessor and produce electron/photon, tau, and jet trigger multiplicities, total and missing transverse energies, and Region-of-Interest (RoI) information. Data are read out to the data acquisition (DAQ) system to monitor the trigger by using readout driver modules (ROD). A dedicated backplane has been designed to cope with the demanding requirements of the CP and JEP sub-systems. A number of pre-production boards were manufactured in order to fully populate a crate and test the robustness of the design on a large scale. Dedicated test modules to emulate digitised calorimeter signals have been used. All modules, cables and backplanes on test are final versions for use at the LHC. This test rig represents up to one third of the Level-1 digital processor system. Real-time data between modules were processed and time-slice readout data was transferred to the ROD at a trigger rate up to 100 kHz. Intensive testing consisted of checking the readout data by comparing to hardware simulations of the trigger. Domains of validity of the boards were also measured and dedicated stressful data patterns were used to check the reliability of the system. Tests results have been successful and the Level-1 calorimeter trigger system is proceeding to full production.
Achcnbach R, Andrei V, Bauss B, et al., 2007, Large scale production of the multi-chip module of the ATLAS Level-calorimeter trigger, Pages: 542-546
The Multi-Chip Module (MCM) is the main processing block of the Pre-Processor System in the ATLAS Level-1 Calorimeter Trigger, The MCM holds a dedicated signal-processing ASIC and a Phos4 timing-chip together with seven commercial dice mounted on the substrate, Those are four f;ADCs and three LVDS-seriahzers. The MCM contains the main functionality of Ihc Preprocessor System, namely the digiti/atkm, calibration and Bimch-CrossingTdesUifieatiofi of calorimeter signals, Two output data streams are produced by the MCM, A real-time stream transmits the processed data to the subsequent trigger processors. A readout stream provides readout information of the Preprocessor, The MCM is the smallest exchangeable unit of the Preprocessor. The ATLAS experiment will have 2048 MCMs installed in the Pre-Proeessor system. Including spares, the total number runs up to 3000, The production phases of the MCMs and test procedures for quality control at different stages of the production arc presented.
Schael S, Barate R, Bruneliere R, et al., 2007, Fermion pair production in <i>e</i><SUP>+</SUP><i>e</i><SUP>-</SUP> collisions at 189-209 GeV and constraints on physics beyond the standard model, EUROPEAN PHYSICAL JOURNAL C, Vol: 49, Pages: 411-437, ISSN: 1434-6044
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- Citations: 54
Schael S, Barate R, Bruneliere R, et al., 2007, Search for Higgs bosons decaying to WW in <i>e</i><SUP>+</SUP><i>e</i><SUP>-</SUP> stope collisions at LEP, EUROPEAN PHYSICAL JOURNAL C, Vol: 49, Pages: 439-455, ISSN: 1434-6044
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- Citations: 6
Aubert B, Bona M, Boutigny D, et al., 2007, Inclusive <i>Λ</i><SUP>+</SUP><sub>c</sub> production in e<SUP>+</SUP>e<SUP>-</SUP> annihilations at √s=10.54 GeV and in <i>Y</i>(4<i>S</i>) decays, PHYSICAL REVIEW D, Vol: 75, ISSN: 2470-0010
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- Citations: 19
Aubert B, Barate R, Bona M, et al., 2007, Improved measurements of the branching fractions for <i>B</i><SUP>0</SUP>→π<SUP>+</SUP> π<SUP>-</SUP> and <i>B</i><SUP>0</SUP>→<i>K</i><SUP>+</SUP> π<SUP>-</SUP>, and a search for <i>B</i><SUP>0</SUP>→<i>K</i><SUP>+</SUP> <i>K</i><SUP>-</SUP>, PHYSICAL REVIEW D, Vol: 75, ISSN: 1550-7998
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- Citations: 34
Adzic P, Sharp P, 2007, Energy resolution of the barrel of the CMS electromagnetic calorimeter, Journal of Instrumentation, Vol: 2
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