124426208
SEARCH FOR LIGHT SUPERSYMMETRIC BARYONS
We have searched for the production and decay of light supersymmetric baryons produced in 800 GeV/c proton copper interactions in a charged hyperon beam experiment. We observe no evidence for the decays R{sup +}(uud{tilde g}){r_arrow} S{sup 0}(uds{tilde g}){pi}{sup +} and X{sup -}(ssd{tilde g}){r_arrow} S{sup 0}(uds{tilde g}){pi}{sup -} in the parent mass and lifetime ranges of 1700{endash}2500 MeV/c{sup 2} and 50{endash}500ps. Production upper limits for R{sup +} at x{sub F}=0.47, P{sub t}=1.4GeV/c{sup 2} and X{sup -} at x{sub F}=0.48, P{sub t}=0.65GeV/c{sup 2} of less than 10{sup -3} of all charged secondary particles produced are obtained for all but the highest masses and shortest lifetimes predicted. {copyright} {ital 1997} {ital The American Physical Society}
110549737
Performance evaluation of a hit finding algorithm for the ICARUS detector
Abstract A procedure to filter the ICARUS digitized data is presented. The final multi-kiloton detector will provide raw data at a rate of the order of 100 Gbytes/s and therefore a crucial element of the acquisition chain will be the on-line data reduction system. A filter has been developed to process the signals and to tag the meaningful data. The hit detection efficiency has been evaluated on a sample of signals obtained from cosmic rays events in the 3 t ICARUS prototype. Its robustness has been tested also on simulated events with different signal to noise ratio. The hit finder hardware implementation is also presented.
38205739
Measurement of the branching ratio for the Xi ---> Sigma - gamma radiative decay.
We have measured the branching ratio for the hyperon radiative decay XI- --> SIGMA- gamma from a sample of 211 +/- 33 events obtained in the polarized 375 GeV/c charged hyperon beam at Fermilab. We find B(XI- --> SIGMA- gamma/XI- --> LAMBDA0pi-) = (1.22 +/- 0.23 +/- 0.06) X 10(-4) where the quoted errors are statistical and systematic, respectively. We have also obtained an indication that the sign of the asymmetry parameter of this decay is positive.
358442
New upper limit for the branching ratio of the Omega ---> Xi - gamma radiative decay.
We have searched for the rare hyperon radiative decay Omega- to Xi- gamma, using the Fermilab Proton Center 375 GeV/c charged hyperon beam. Our measurement of the Omega- beam fraction at 13.6 m from production is (4.8 +_ 0.4)10**(-5). No signal was found and we determine a new upper limit of (4.6 x 10**-4) at 90% CL for the Omega- to Xi- gamma branching ratio.
13975142
Calibration of BC501A liquid scintillator cells with monochromatic neutron beams
Abstract The recoil proton energy response has been measured by exposing cylindrical cells, filled with BC501A BICRON liquid scintillator, to mono-energetic neutron reference fields. We determine the required calibration parameters and report the detailed procedures for the experimental data handling. A dedicated Monte Carlo simulation of the detector response and efficiency has been performed. It showed good agreement with the measured quantities. The results from this calibration are necessary for a detailed study of the neutron spectrum at the underground Gran Sasso Laboratory, with a neutron detector made of 32 liquid scintillator cells, like those used during the calibration.
53366228
BLACK HOLES IN THE PRESENCE OF COSMOLOGICAL CONSTANT AND LARGE-N BRANE WORLD
Gravitational theories including negative cosmological constant, dilaton and gauge fields are explored in higher dimensions, in which black hole solutions are shown to exist and their asymptotic behaviors are obtained. Based on these solutions, effective Randall–Sundrum brane worlds are constructed. In the framework of gauge/gravity duality, effects from cosmological constant on the spectra of standard model fields on the branes are perturbatively calculated.
89610769
Constraints on natural supersymmetry from electroweak precision tests
A bstractThe observed Higgs boson mass and the naturalness argument leave us a narrow window for the soft mass spectrum in natural supersymmetry that can be studied through the electroweak precision tests (EWPTs). We divide the analysis into the Higgs sector constrained by the charged Higgs mass bound, the neutralino-chargino sector constrained by the chargino mass bound, and the third-generation squark sector tightly constrained by the observed Higgs mass. Total contributions to EWPTs in the MSSM and NMSSM are both presented. It turns out that natural MSSM is excluded at 68% CL but consistent at 95% CL, whereas natural NMSSM with nearly degenerate conditions is excluded at 68% CL but consistent at 99% CL for λ ≤ 0.6.