131 research outputs found
Study of multi-muon events produced in p\bar{p} interactions at \sqrt{s}=1.96 TeV
68 pages, 46 figures, 11 tables. Submitted to Phys. Rev. D. Removed typos from the authors' listWe report the results of a study of multi-muon events produced at the Fermilab Tevatron collider and acquired with the CDF II detector using a dedicated dimuon trigger. The production cross section and kinematics of events in which both muon candidates are produced inside the beam pipe of radius 1.5 cm are successfully modeled by known processes which include heavy flavor production. In contrast, we are presently unable to fully account for the number and properties of the remaining events, in which at least one muon candidate is produced outside of the beam pipe, in terms of the same understanding of the CDF II detector, trigger, and event reconstruction.Peer reviewe
Search for the highly suppressed decays B- -> K+Ï€-Ï€- and B- -> K-K-Ï€+
We report a search for the decays B- -> K+pi(-)pi(-) and B- -> K-K-pi(+), which are highly suppressed in the standard model. Using a sample of (467 +/- 5) x 10(6) B (B) over bar pairs collected with the BABAR detector, we do not see any evidence of these decays and determine 90% confidence level upper limits of B(B- -> K+pi(-)pi(-)) and K-K-pi(+)) and < 1.6 x 10(-7) on the corresponding branching fractions, including systematic uncertainties
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Aqueously altered igneous rocks sampled on the floor of Jezero crater, Mars.
The Perseverance rover landed in Jezero crater, Mars, to investigate ancient lake and river deposits. We report observations of the crater floor, below the crater's sedimentary delta, finding that the floor consists of igneous rocks altered by water. The lowest exposed unit, informally named SéÃtah, is a coarsely crystalline olivine-rich rock, which accumulated at the base of a magma body. Magnesium-iron carbonates along grain boundaries indicate reactions with carbon dioxide-rich water under water-poor conditions. Overlying SéÃtah is a unit informally named Máaz, which we interpret as lava flows or the chemical complement to SéÃtah in a layered igneous body. Voids in these rocks contain sulfates and perchlorates, likely introduced by later near-surface brine evaporation. Core samples of these rocks have been stored aboard Perseverance for potential return to Earth
Measurement of CP violation observables and parameters for the decays B-+/--> DK*+/-
We study the decay B--> DK*- using a sample of 379x10(6) Upsilon(4S)-> BB events collected with the BABAR detector at the PEP-II B factory. We perform a Gronau-London-Wyler analysis where the D meson decays into either a CP-even (CP+) eigenstate (K+K-, pi(+)pi(-)), CP-odd (CP-) eigenstate (K-S(0)pi(0), K-S(0)phi, K-S(0)omega) or a non-CP state (K-pi(+)). We also analyze D meson decays into K+pi(-) from a Cabibbo-favored D-0 decay or doubly suppressed D-0 decay [Atwood-Dunietz-Soni (ADS) analysis]. We measure observables that are sensitive to the Cabibbo-Kobayashi-Maskawa angle gamma: the partial-rate charge asymmetries A(CP +/-), the ratios R-CP +/- of the B-decay branching fractions in CP +/- and non-CP decay, the ratio R-ADS of the charge-averaged branching fractions, and the charge asymmetry A(ADS) of the ADS decays: A(CP+)=0.09 +/- 0.13 +/- 0.06, A(CP-)=-0.23 +/- 0.21 +/- 0.07, RCP+=2.17 +/- 0.35 +/- 0.09, RCP-=1.03 +/- 0.27 +/- 0.13, R-ADS=0.066 +/- 0.031 +/- 0.010, and A(ADS)=-0.34 +/- 0.43 +/- 0.16, where the first uncertainty is statistical and the second is systematic. Combining all the measurements and using a frequentist approach yields the magnitude of the ratio between the Cabibbo-suppressed and favored amplitudes, r(B)=0.31 with a one (two) sigma confidence level interval of [0.24, 0.38] ([0.17, 0.43]). The value r(B)=0 is excluded at the 3.3 sigma level. A similar analysis excludes values of gamma in the intervals [0, 7]degrees, [55, 111]degrees, and [175, 180]degrees ([85, 99]degrees) at the one (two) sigma confidence level
Correlated leading baryon-antibaryon production in e(+)e(-) -> c(c)over-bar -> Lambda(+)(c)(Lambda)over-bar(c)(-)X
We present a study of 649 +/- 35 e(+)e(-) -> c (c) over bar events produced at root s approximate to 10.6 GeV containing both Lambda(+)(c) baryon and a (Lambda) over bar (-)(c) antibaryon. The number observed is roughly 4 times that expected if the leading charmed hadron types are uncorrelated, confirming an observation by the CLEO Collaboration. We find a 2-jet topology in these events but very few additional baryons, demonstrating that the primary c and (c) over bar are predominantly contained in a correlated baryon-antibaryon system. In addition to the charmed baryons we observe on average 2.6 +/- 0.2 charged intermediate mesons, predominantly pions, carrying 65% of the remaining energy
Study of hadronic transitions between Y states and observation of Y(4S) -> eta Y(1S) decay
We present a study of hadronic transitions between Y(mS) (m = 4, 3, 2) and Y(nS) (n = 2, 1) resonances based on 347.5 fb(-1) of data taken with the BABAR detector at the PEP-II storage rings. We report the first observation of Y(4S) -> eta Y(1S) decay with a branching fraction B(Y(4S) -> eta Y(1S) = (1.96 +/- 0.06(stat) +/- 0.09(syst)) X 10(-4) and measure the ratio of partial widths Gamma(Y(4S) -> eta Y(1S))/Gamma(Y(4S) -> pi(+)pi Y-(1S)) = 2.41 +/- 0.40(stat) +/- 0.12(syst). We set 90% CL upper limits on the ratios Gamma(Y(2S) -> eta Y(1S))/Gamma(Y(2S) -> pi(+)pi Y-(1S) eta Y(1S)/Gamma(Y(3S) -> pi(+)pi Y-(1S)) pi(+)pi Y-(2S)/Gamma(Y(4S) -> pi(+)pi Y-(1S)) = 1.16 +/- 0.16(stat) +/- 0.14(syst) and Gamma(Y(3S) -> pi(+)pi Y-(1S)) = 0.577 +/- 0.026(stat) +/- 0.060(syst)
Search for Charged Lepton Flavor Violation in Narrow Gamma Decays
Charged-lepton flavor-violating processes are unobservable in the standard model, but they are predicted to be enhanced in several extensions to the standard model, including supersymmetry and models with leptoquarks or compositeness. We present a search for such processes in a sample of 99 x 10(6)Gamma(2S) decays and 117 x 10(6)Gamma(3S) decays collected with the BABAR detector. We place upper limits on the branching fractions B(Gamma(nS) --> e(+/-)tau(-/+)) and B(Gamma(n(S) --> mu(+/-)tau(-/+)) (n = 2, 3) at the 10(-6) level and use these results to place lower limits of order 1 TeV on the mass scale of charged-lepton flavor-violating effective operators. RI Patrignani, Claudia/C-5223-2009; Neri, Nicola/G-3991-2012; Monge, Maria Roberta/G-9127-201
Search for a low-mass Higgs Boson in upsilon(3S) -> gamma A(0), A(0) -> tau(+) tau(-) at BABAR
We search for a light Higgs boson A(0) in the radiative decay Upsilon(3S) -> gamma A(0), A(0) -> tau(+) tau(-), tau(+) -> e(+) nu(e)(nu) over bar (tau) or tau(+) -> mu(+) nu(mu)(nu) over bar (tau) . The data sample contains 122 X 10(6) Upsilon(3S) events recorded with the BABAR detector. We find no evidence for a narrow structure in the studied tau(+) tau(-) invariant mass region of 4.03 A(0)) B(A(0) -> tau(+) tau(-)) > (1.5 - 16) X 10(-5) across the m(tau+ tau-) range. We also set a 90% C. L. upper limit on the tau(+) tau(-) decay of the eta(b) at B(eta(b) -> tau(+) tau(-)) < 8%
Measurement of the Branching Fractions of (B)over-bar -> D**l(-)(v)over-bar(l) Decays in Events Tagged by a Fully Reconstructed B Meson RID C-5223-2009
We report a measurement of the branching fractions of B -> D**l(-)(v) over bar (l) decays based on 417 fb(-1) of data collected at the Y(4S) resonance with the BABAR detector at the PEP-II e(+) e(-) storage rings. Events are selected by fully reconstructing one of the B mesons in a hadronic decay mode. A fit to the invariant mass differences m(D(()*())pi) - (m(D(()*())) is performed to extract the signal yields of the different D** states. We observe the (B) over bar -> D**l(-)(v) over bar (l) decay modes corresponding to the four D** states predicted by heavy quark symmetry with a significance greater than 5 standard deviations including systematic uncertainties
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