6984599
Search for a light Higgs resonance in radiative decays of the (1S) with a charm tag
A search is presented for the decay Υ(1S)→ γA^0, A^0 → cc[bar], where A^0 is a candidate for the CP-odd Higgs boson of the next-to-minimal supersymmetric standard model. The search is based on data collected with the BABAR detector at the Υ(2S) resonance. A sample of Υ(1S) mesons is selected via the decay Υ(2S)→π + π − Υ(1S). The A^0 → cc[bar] decay is identified through the reconstruction of hadronic D^0, D^+, and D^∗ (2010)^+ meson decays. No significant signal is observed. The measured 90% confidence-level upper limits on the product branching fraction B(Υ(1S) → γA^0 ) × B(A^0 → cc[bar] ) range from 7.4×10^(−5) to 2.4×10^(−3) for A^0 masses from 4.00 to 8.95  GeV/c^2 and 9.10 to 9.25  GeV/c^2, where the region between 8.95 and 9.10  GeV/c^2 is excluded because of background from Υ(2S) → γχ_(bJ) (1P), χ_(bJ) (1P) → γΥ(1S) decays.
118033184
Status of the Compact Muon Solenoid Detector at the Large Hadron Collider
The Compact Muon Solenoid (CMS) detector is being constructed at the Large Hadron Collider (LHC) at CERN for the purpose of exploring new physics in proton‐proton collisions at 14 TeV. The detector is to be designed, constructed and commissioned in time for the start of the LHC in April 2007. This article summarizes the current status of the detector and foreseen program for completion.
124136703
Improved Constraints on the Neutralino Cold Dark Matter Candidate from the Search for Chargino and Neutralino Production Using the OPAL Detector at 170 ÷ 172 Gev at LEP
New limits on the cold dark matter candidate, the lightest neutralino \(\left( {\tilde x_1^0} \right)\), are obtained from a search for charginos and neutralinos using a data sample of 10.3 pb−1 at the center-of-mass energies of √s =170 and 172 GeV with the OPAL detector at LEP.
120601772
Validating Geant4 Versions 7.1 and 8.3 Against 6.1 for BaBar
Since 2005 and 2006, respectively, Geant4 versions 7.1 and 8.3 have been available, providing: improvements in modeling of multiple scattering; corrections to muon ionization and improved MIP signature; widening of the core of electromagnetic shower shape profiles; newer implementation of elastic scattering for hadronic processes; detailed implementation of Bertini cascade model for kaons and lambdas, and updated hadronic cross-sections from calorimeter beam tests. The effects of these changes in simulation are studied in terms of closer agreement of simulation using Geant4 versions 7.1 and 8.3 as compared to Geant4 version 6.1 with respect to data distributions of: the hit residuals of tracks in BABAR silicon vertex tracker; the photon and KOL shower shapes in the electromagnetic calorimeter; the ratio of energy deposited in the electromagnetic calorimeter and the flux return of the magnet instrumented with a muon detection system composed of resistive plate chambers and limited-streamer tubes; and the muon identification efficiency in the muon detector system of the BaBar detector.
16601897
Mechanisms affecting performance of the BaBar resistive plate chambers and searches for remediation
The BaBar experiment at PEPII relies on the instrumentation of the flux return (IFR) for both muon identification and KL detection. The active detector is composed of resistive plate chambers (RPCs) operated in streamer mode. Since the start of operation the RPCs have suffered persistent efficiency deterioration and dark current increase problems. The ‘‘autopsy’’ of bad BaBar RPCs revealed that in many cases uncured linseed oil droplets had formed on the inner surface of the Bakelite plates, leading to current paths from oil ‘‘stalagmites’’ bridging the 2mm gap. In this paper, a possible model of this ‘‘stalagmite’’ formation and its effect on the dark current and efficiency of RPC chambers is presented. Laboratory test results strongly support this model. ARTICLE IN PRESS *Corresponding author. Tel.: +1-609-258-4391; fax: +1-609-258-6360. E-mail address: changguo@princeton.edu (C. Lu). 0168-9002/03/$ see front matter r 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0168-9002(03)01292-0 Based upon this model we are searching for solutions to eliminate the unfavorable effect of the oil stalagmites. The lab tests show that the stalagmite resistivity increases dramatically if exposed to the air, an observation that points to a possible way to remedy the damage and increase the efficiency. We have seen that flowing an oxygen gas mixture into the chamber helps to polymerize the uncured linseed oil. Consequently, the resistivity of the bridged oil stalagmites increases, as does that of the oil coating on the frame edges and spacers, significantly reducing the RPC dark currents and low-efficiency regions. We have tested this idea on two chambers removed from BaBar because of their low efficiency and high dark current. These test results are reported in the paper, and two other remediation methods also mentioned. We continue to study this problem, and try to find new treatments with permanent improvement. r 2003 Elsevier Science B.V. All rights reserved.
2708913
Monolithic CMOS Pixel Detectors for ILC Vertex Detection
A CMOS pixel vertex detector suited for use at the International Linear Collider (ILC) is proposed. The proposed detector consists of 50µm ◊ 50µm macropixels, each with integrated bunch clock memory, on top of 5µm ◊ 5µm micropixels that record amplitude information. The micropixels integrate over all bunch crossing in a train. Using the time recorded by the macropixels, the fine position measurements made in the micropixels can be associated to only a few of the 3000 bunch crossings in a bunch train.
117806093
Preliminary Polarization Results at Fermilab Energies
This paper describes the jet target, the superconducting spectrometer and the polarimeter used to measure the recoil proton polarization in an Indiana University experiment at the Fermi National Accelerator Laboratory. Analysis procedures and data checks are explained and preliminary results are presented and compared with model predictions. The future plans of the experiment are also discussed.
125810791
Plans for the study of the spin properties of the Lambda/b baryon using the decay channel Lambda/b ---> J/psi (mu+ mu-) Lambda (p pi-)
122492733
Proton polarization in inclusive processes at 100, 200, 300, and 400 GeV
We have measured the polarization of the out going proton in the following high energy interactions: p+C..-->..p/sup arrow-up/+x and p+p..-->..pup-arrow+x. Our measurements span the P/sub T/ range .5..-->..1.5 GeV/c energies of 100, 200, 300, 400 GeV at the internal target area at Fermi National Accelerator Laboratory.
117954951
Planned Spin Studies at the Large Hadron Collider
This note summarizes how quantum spin can elucidate the physics of new energy regimes and presents a selection of planned studies at the LHC in which spin is expected to have special relevance.
120561779
INTERMEDIATE-ANGLE PION--PROTON ELASTIC SCATTERING FROM 3.0 TO 5.0 GeV/c.