arXiv subjects

the BABAR Collaboration

Publications and source records attributed to the BABAR Collaboration.

8 recordsLinked to original sources

arXiv2011

Observation of the $Υ(1^3D_J)$ Bottomonium State through Decays to $π^+π^-Υ(1S)$

Based on $122\times 10^6$ \ThreeS events collected with the \babar\ detector, we have observed the \OneDJ bottomonium state through the $\ThreeS\to\g\g\OneDJ\to\g\g\pip\pim\OneS$ decay chain.The significance for the $J=2$ member of the \OneDJ triplet is 5.8 standard deviations including systematic uncertainties.The mass of the $J=2$ state is determined to be $10164.5\pm0.8\,\rm{(stat.)}\pm0.5\,\rm{(syst.)}$~\mevcc.We use the $\pip\pim$ invariant mass distribution to confirm the consistency of the observed state with the orbital angular momentum assignment of the \OneDJ.

hep-ex↗

arXiv2004

Search for b --> u Transitions in B- to D0(bar)K- and B- to D*0(bar)K-

We report on searches for B- to D0(bar) K- and B- to D*0(bar) K-, with D*0(bar) to D0(bar) pi0 or D*0(bar) to D0(bar) gamma, and D0(bar) to K+ pi- (and charge conjugates). These final states, which we denote as [K+pi-]_D K- and [K+pi-]_D* K-, can be reached through the b --> c transition B- to D(*)0 K- followed by the doubly Cabibbo-suppressed D0 to K+ pi-, or through the b --> u transition B- to D0bar K- followed by the Cabibbo-favored D0bar to K+ pi-, or through interference of the two. Our results are based on 227 million Upsilon(4s) to BBbar decays collected with the BaBar detector at SLAC. We measure the ratio R_Kpi == (Gamma(B+ to [K-pi+]_D K+) + Gamma(B- to [K+pi-]_D K-))/ (Gamma(B+ to [K+pi-]_D K+) + Gamma(B- to [K-pi+]_D K-)) = 0.013 + 0.011 - 0.009, R*_Kpi,D0pi0 == (Gamma(B+ to [K-pi+]_D*(pi0) K+) + Gamma(B- to [K+pi-]_D*(pi0) K-)) (Gamma(B+ to [K+pi-]_D*(pi0) K+) + Gamma(B- to [K-pi+]_D*(pi0) K-)) = -0.001 + 0.010 - 0.006 and R*_Kpi,D0gam == (Gamma(B+ to [K-pi+]_D*(gam) K+) + Gamma(B- to [K+pi-]_D*(gam) K-)) (Gamma(B+ to [K+pi-]_D*(gam) K+) + Gamma(B- to [K-pi+]_D*(gam) K-)) = 0.011 + 0.019 - 0.013. We set R_Kpi < 0.030 (90% C.L.) and from this limit we extract the amplitude ratio rB == |A(B- to D0bar K-)/A(B- to D0 K-)| < 0.23 at the 90% confidence level. This limit is obtained with the most conservative assumptions on the values of the CKM angle gamma and the strong phases in the B and D decay amplitudes. From the measurements of R*_Kpi,D0pi0 and R*_Kpi,D0gam we extract rB*^2 == |A(B- to D*0bar K-)/A(B- to D*0 K-)|^2 = 4.6 + 15.2 - 7.3 x 10-3 and rB*^2<(0.16)^2 at the 90% confidence level.

hep-ex↗

arXiv2003

Observation of a Narrow Meson Decaying to Ds+pi0 at a Mass of 2.32 GeV/c^2

We have observed a narrow state near 2.32 GeV/c^2 in the inclusive Ds+ pi0 invariant mass distributionfrom e+e- annihilation data at energies near 10.6 GeV. The observed width is consistent with the experimental resolution. The small intrinsic width and the quantum numbers of the final state indicate that the decay violates isospin conservation. The state has natural spin-parity and the low mass suggests a JP=0+ assignment. The data sample corresponds to an integrated luminosity of 91 fb-1 recorded by the BABAR detector at the PEP2 asymmetric-energy e+e- storage ring.

hep-ex↗

arXiv2003

Search for the decay B^0 --> gamma-gamma

We present a limit on the branching fraction for the decay $B^0 \to γγ$ using data collected at the $Υ(4S)$ resonance with the BABAR detector at the PEP-II asymmetric--energy $e^+e^-$ collider. Based on the observation of one event in the signal region, out of a sample of $21.3 \times 10^6$ $e^+e^- \to Υ(4S) \to B\bar B$ decays, we establish an upper limit on the branching fraction of ${\cal B}(B^0 \to γγ) < 1.7 \times 10^{-6}$ at the 90% confidence level. This result substantially improves upon existing limits.

hep-ex↗

arXiv2003

Study of semi-inclusive production of eta' mesons in B decays

We report a measurement of the rate for $B \to η' X_s$ transitions where the $η'$ meson has center-of-mass momentum in the range 2.0 to 2.7\gevc and $X_s$ represents a system comprising a kaon and up to four pions. Our study is based on 22.2 million $B\bar{B}$ pairs collected at the $Υ(4S)$ with the BABAR detector at the Stanford Linear Accelerator Center. We find $\mathcal{B}(B \to η' X_s)=(6.8^{+0.7}_{-1.7}(stat)\pm1.0(syst)^{+0.0}_{-0.5}(bkg))\times10^{-4}$ assuming that the signal is due to $b \to sg^*$ transitions.

hep-ex↗

arXiv2003

Measurement of the branching fractions for psi(2S)-->e+e- and psi(2S)-->mu+mu-

We measure the branching fractions of the psi(2S) meson to the leptonic final states e+e- and mu+mu- relative to that for psi(2S)-->J/psi pi+pi-. The method uses psi(2S) mesons produced in the decay of B mesons at the Upsilon(4S) resonance in a data sample collected with the BABAR detector at the Stanford Linear Accelerator Center. Using previous measurements for the psi(2S)-->J/psi pi+pi- branching fraction, we determine the e+e- and mu+mu- branching fractions to be 0.0078+/-0.0009+/-0.0008 and 0.0067+/-0.0008+/-0.0007 respectively.

hep-ex↗

arXiv2002

Simultaneous Measurement of the B0 Meson Lifetime and Mixing Frequency with B0 --> D*- l+ nu Decays

We measure the B0 lifetime τ_{B0} and the B0-B0bar oscillation frequency Δm_d with a sample of approximately 14,000 exclusively reconstructed B0 --> D*- l+ nu signal events, selected from 23 million BBbar pairs recorded at the Υ(4S) resonance with the BABAR detector at the Stanford Linear Accelerator Center. The decay position of the other B is determined with the remaining tracks in the event, and its b-quark flavor at the time of decay is determined with a tagging algorithm that exploits the correlation between the flavor of the b-quark and the charges of its decay products. The lifetime and oscillation frequency are measured simultaneously with an unbinned maximum-likelihood fit that uses, for each event, the measured difference in decay times of the two B mesons (Δt), the calculated uncertainty on Δt, the signal and background probabilities, and b-quark tagging information for the other B. The results are τ_{B^0} = (1.523^{+0.024}_{-0.023} \pm 0.022) \rm{ps} and Δm_d = (0.492 \pm 0.018 \pm 0.013) \rm{ps}^{-1}. The statistical correlation coefficient between τ_{B0} and Δm_d is -0.22.

hep-ex↗

arXiv2001

Search for B^0 --> a_0^+(980)pi^-

We present preliminary results of a search for the decay B^0 --> a_0^+(980)pi^- among 22.7 million Upsilon(4S)-->B-anti-B pairs collected by the BABAR detector at PEP-II. Using improved background suppression techniques and optimal signal extraction for rare decay searches, an excess of events over expected background is observed at the level of 3.7 standard deviations. This corresponds to the branching fraction BR(B^0 --> a_0^+ (a_0^+ --> eta pi^+) pi^-) =(6.2_{-2.5}^{+3.0}+/-1.1) x 10^{-6}, where the first error is statistical and the second is systematic. The 90% confidence level upper limit is 11.5 x 10^{-6}.

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