Beam tests and calibration of the H1 liquid argon calorimeter with electrons
Nuclear instruments and methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment/Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/1994
Journal Article
Peer reviewed
Open access
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We measure the total branching fraction of the flavor-changing neutral-current process B → X s ℓ + ℓ − , along with partial branching fractions in bins of dilepton and hadronic system ( X s ) mass, ...using a sample of 471 × 1 0 6 Υ ( 4 S ) → B ¯ B events recorded with the BABAR detector. The admixture of charged and neutral B mesons produced at PEP-II2 are reconstructed by combining a dilepton pair with 10 different X s final states. Extrapolating from a sum over these exclusive modes, we measure a lepton-flavor-averaged inclusive branching fraction B ( B → X s ℓ + ℓ − ) = 6.7 3 + 0.70 − 0.64 ( stat ) + 0.34 − 0.25 ( exp syst ) ± 0.50 ( model syst ) × 1 0 − 6 for m 2 ℓ + ℓ − > 0.1 GeV 2 / c 4 . Restricting our analysis exclusively to final states from which a decaying B meson's flavor can be inferred, we additionally report measurements of the direct C P asymmetry A C P in bins of dilepton mass; over the full dilepton mass range, we find A C P = 0.04 ± 0.11 ± 0.01 for a lepton-flavor-averaged sample.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
We describe searches for B meson decays to the charmless vector-vector final states omega omega and omega phi with 471 x 10^6 B Bbar pairs produced in e+ e- annihilation at sqrt(s) = 10.58 GeV using ...the BABAR detector at the PEP-II collider at the SLAC National Accelerator Laboratory. We measure the branching fraction B(B0 --> omega omega) = (1.2 +- 0.3 +0.3-0.2) x 10^-6, where the first uncertainty is statistical and the second is systematic, corresponding to a significance of 4.4 standard deviations. We also determine the upper limit B(B0 --> omega phi) < 0.7 x 10^-6 at 90% confidence level. These measurements provide the first evidence for the decay B0 --> omega omega, and an improvement of the upper limit for the decay B0 --> omega phi.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
We present results of a search for CP violation in B0B0bar mixing with the BABAR detector. We select a sample of B0-->D*-Xl+ nu decays with a partial reconstruction method and use kaon tagging to ...assess the flavor of the other B meson in the event. We determine the CP violating asymmetry ACP = (N(B0B0) - N(B0bar B0bar))/(N(B0B0) + N(B0bar B0bar))=(0.06+-0.17+0.38-0.32)%, corresponding to delta_CP =1 - |q/p| =(0.29+-0.84+1.88 -1.61)*10^-3.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
The photon spectrum in the inclusive electromagnetic radiative decays of the $B$ meson, $B \to X_{s} \gamma$ plus $B \to X_{d} \gamma$, is studied using a data sample of $(382.8 \pm 4.2) \times 10^6$ ...$\Upsilon(4S) \to B\overli\ ne{B}$ decays collected by the \babar\ experiment at SLAC. The spectrum is used to extract the branching fraction ${\cal B}(B \to X_{s} \gamma)=(3.21 \pm 0.33)\times 10^{-4}$ for $E_{\gamma}>1.8 \gev$ and the direct CP asymmetry $A_{CP}(B \to X_{s+d} \gamma)=0.057 \pm 0.063$. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the $B$ meson rest frame.
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A measurement of the proton structure function F_{\!2}(x,Q^2) is reported for momentum transfer squared Q^2 between 4.5 GeV^2 and 1600 GeV^2 and for Bjorken x between 1.8\cdot10^{-4} and 0.13 using ...data collected by the HERA experiment H1 in 1993. It is observed that F_{\!2} increases significantly with decreasing x, confirming our previous measurement made with one tenth of the data available in this analysis. The Q^2 dependence is approximately logarithmic over the full kinematic range covered. The subsample of deep inelastic events with a large pseudo-rapidity gap in the hadronic energy flow close to the proton remnant is used to measure the "diffractive" contribution to F_{\!2}.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
9.
The DIRC particle identification system for the B aB ar experiment Adam, I.; Aleksan, R.; Amerman, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2005, Volume:
538, Issue:
1
Journal Article
Peer reviewed
A new type of ring-imaging Cherenkov detector is being used for hadronic particle identification in the B
aB
ar experiment at the SLAC B Factory (PEP-II). This detector is called DIRC, an acronym for ...Detection of Internally Reflected Cherenkov (Light). This paper will discuss the construction, operation and performance of the B
aB
ar DIRC in detail.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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