arXiv subjects

The BABAR Collaboration

Publications and source records attributed to The BABAR Collaboration.

At least 19 recordsLinked to original sources

arXiv2025

Study of $\chi_{b1,2}(2P) \to \omega \Upsilon(1S)$ transitions in $\Upsilon(3S) \to \gamma \chi_{b1,2}(2P)$ decays at BaBar

Results are presented on $\chi_{b1,2}(2P) \to \omega \Upsilon(1S)$ transitions from $e^+e^- \to \Upsilon(3S) \to \gamma \chi_{b1,2}(2P)$ decays. The data were collected with the BaBar detector at the PEP-II asymmetric-energy $e^+e^-$ collider at SLAC. The integrated luminosity of the data sample is 28.0 fb$^{-1}$, corresponding to $121.3 \times 10^6$ $\Upsilon(3S)$ decays. Signals of $\chi_{b1,2}(2P)$ are observed over a negligible background. Improved precision measurements of branching fractions are obtained. First measurements of the $\chi_{b1,2}(2P)$ angular distributions are performed. No evidence is found for the presence of a $\chi_{b0}(2P) \to \omega \Upsilon(1S)$ decay mode.

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arXiv2023

Search for Evidence of Baryogenesis and Dark Matter in $B^{+} \rightarrow ψ_{\text{D}} + \text{p} $ Decays at BABAR

A new dark sector anti-baryon, denoted $ψ_{\text{D}}$, could be produced in decays of $B$ mesons. This letter presents a search for $B^{+} \rightarrow ψ_{\text{D}} + \text{p}$ (and the charge conjugate) decays in $e^{+}e^{-}$ annihilations at 10.58 GeV, using data collected in the ~\babar~ experiment. Data corresponding to an integrated luminosity of 398 fb$^{-1}$ are analyzed. No evidence for a signal is observed. Branching fraction upper limits in the range from $10^{-7} $ -- $ 10^{-5}$ are obtained at 90$\%$ confidence level for masses of 1.0 $< m_{ψ_{\text{D}}} < $ 4.3 GeV/c$^{2}$. The result is also reinterpreted to provide the first limits on a supersymmetric model with R-parity violation and a light neutralino.

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arXiv2023

Precision $e^-$ Beam Polarimetry at an $e^+e^-$ B Factory using Tau-Pair Events

We present a new technique, `Tau Polarimetry', for measuring the longitudinal beam polarization present in an $e^+e^-$ collider through the analysis of $e^+e^-\rightarrowτ^+τ^-$ events. By exploiting the sensitivity of $τ$ decay kinematics to the longitudinal polarization of the beams, we demonstrate that the longitudinal polarization can be measured with a 3 per mil systematic uncertainty at the interaction point using a technique that is independent of spin and beam transport modeling. Using 424.2$\pm$1.8 fb$^{-1}$ of BABAR data at $\sqrt{s}=10.58$ GeV, the average longitudinal polarization of the PEP-II $e^+e^-$ collider has been measured to be $\langle P\rangle=0.0035 \pm 0.0024_{\textrm{stat}}\pm 0.0029_{\textrm{sys}}$. The systematic uncertainty studies are described in detail, which can serve as a guide for future applications of Tau Polarimetry. A proposed $e^-$ beam longitudinal polarization upgrade to the SuperKEKB $e^+e^-$ collider would benefit from this technique.

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arXiv2021

Study of the process $e^+e^-\to π^+π^-π^0$ using initial state radiation with BABAR

The process $e^+e^-\to π^+π^-π^0γ$ is studied at a center-of-mass energy near the $Υ(4S)$ resonance using a data sample of 469 fb$^{-1}$ collected with the BABAR detector at the PEP-II collider. We have performed a precise measurement of the $e^+e^-\to π^+π^-π^0$ cross section in the center-of-mass energy range from 0.62 to 3.5 GeV. In the energy regions of the $ω$ and $ϕ$ resonances, the cross section is measured with a systematic uncertainty of 1.3\%. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the measured $e^+e^-\to π^+π^-π^0$ cross section from threshold to 2.0 GeV is $(45.86 \pm 0.14 \pm 0.58)\times 10^{-10}$. From the fit to the measured $3π$ mass spectrum we have determined the resonance parameters $Γ(ω\to e^+e^-){\cal B}(ω\to π^+π^-π^0)=(0.5698\pm0.0031\pm0.0082) \mbox{ keV}$, $Γ(ϕ\to e^+e^-){\cal B}(ϕ\to π^+π^-π^0)=(0.1841\pm0.0021\pm0.0080) \mbox{ keV}$, and ${\cal B}(ρ\to 3π)=(0.88\pm 0.23\pm 0.30)\times 10^{-4}$. The significance of the $ρ\to 3π$ signal is greater than $6σ$. For the $J/ψ$ resonance we have measured the product ${Γ(J/ψ\to e^+e^-){\cal B}(J/ψ\to 3π)}=(0.1248\pm0.0019\pm0.0026)\mbox{ keV}$.

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arXiv2021

Search for an Axion-Like Particle in B Meson Decays

Axion-like particles (ALPs) are predicted in many extensions of the Standard Model, and their masses can naturally be well below the electroweak scale. In the presence of couplings to electroweak bosons, these particles could be emitted in flavor-changing $B$ meson decays. We report herein a search for an ALP, $a$, in the reaction $B^\pm\rightarrow K^\pm a$, $a\rightarrowγγ$ using data collected by the BABAR experiment at SLAC. No significant signal is observed, and 90% confidence level upper limits on the ALP coupling to electroweak bosons are derived as a function of ALP mass, improving current constraints by several orders of magnitude in the range $0.175\,\,\mathrm{GeV} < m_a < 4.78\,\,\mathrm{GeV}$.

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arXiv2021

Study of the reactions $e^+e^-\to2(π^+π^-)π^0π^0π^0$ and $e^+e^-\to2(π^+π^-)π^0π^0η$ at center-of-mass energies from threshold to 4.5 GeV using initial-state radiation

We study the processes $e^+e^-\to 2(π^+π^-)π^0π^0π^0γ$ and $2(π^+π^-)π^0π^0ηγ$ in which an energetic photon is radiated from the initial state. The data were collected with the \babar~ detector at SLAC. About 14\,000 and 4700 events, respectively, are selected from a data sample corresponding to an integrated luminosity of 469 fb^{-1}. The invariant mass of the hadronic final state defines the effective \epem center-of-mass energy. The center-of-mass energies range from threshold to 4.5 GeV. From the mass spectra, the first ever measurements of the $e^+e^-\to 2(π^+π^-)π^0π^0π^0$ and the $e^+e^-\to2(π^+π^-)π^0π^0η$ cross sections are performed. The contributions from $ωπ^+π^-π^0π^0$, $\eta2(π^+π^-)$, and other intermediate states are presented. We observe the $J/ψ$ and $ψ(2S)$ in most of these final states and measure the corresponding branching fractions, many of them for the first time.

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arXiv2021

Search for Darkonium in $e^+e^-$ Collisions

Collider searches for dark sectors, new particles interacting only feebly with ordinary matter, have largely focused on identifying signatures of new mediators, leaving much of dark sector structures unexplored. In particular, the existence of dark matter bound states (darkonia) remains to be investigated. This possibility could arise in a simple model in which a dark photon ($A'$) is light enough to generate an attractive force between dark fermions. We report herein a search for a $J^{PC}= 1^{--}$ darkonium state, the $Υ_D$, produced in the reaction $e^+e^- \rightarrow γΥ_D, Υ_D \rightarrow A' A' A'$, where the dark photons subsequently decay into pairs of leptons or pions, using $514\text{ fb}^{-1}$ of data collected with the BABAR detector. No significant signal is observed, and we set bounds on the $γ- A'$ kinetic mixing as a function of the dark sector coupling constant for $0.001 < m_{A'} < 3.16 \text{ GeV}$ and $0.05 < m_{Υ_D} < 9.5 \text{ GeV}$.

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arXiv2020

Search for a Dark Leptophilic Scalar at BABAR

Many scenarios of physics beyond the Standard Model predict the existence of new gauge singlets, which might be substantially lighter than the weak scale. The experimental constraints on additional scalars with masses in the MeV to GeV range could be significantly weakened if they interact predominantly with leptons rather than quarks. At an $e^+e^-$ collider, such a leptophilic scalar ($ϕ_L$) would be produced predominantly through radiation from a $τ$ lepton. We report herein a search for $e^+e^- \to τ^+τ^- ϕ_L$, $ϕ_L \to \ell^+\ell^-$ ($\ell=e,μ$) using data collected by the BABAR experiment at SLAC. No significant signal is observed, and we set limits on the $ϕ_L$ coupling to leptons in the range 0.04 < m$_{ϕ_L}$ < 7.0 GeV. These bounds significantly improve upon the current constraints, excluding almost entirely the parameter space favored by the observed discrepancy in the muon anomalous magnetic moment below 4 GeV at 90\% confidence level.

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arXiv2020

Resonances in $e^+e^-$ annihilation near 2.2 GeV

Using the initial-state radiation method, the $e^+e^- \to K_S K_L$ cross section from 1.98 to 2.54 GeV is measured in a data sample of 469 fb$^{-1}$ collected with the BABAR detector. The results are used in conjunction with previous BABAR results for the $e^+e^- \to K^+ K^-$, $e^+e^- \to π^+π^-$, $e^+e^- \to π^+π^-η$, and $e^+e^- \to ωππ$ cross sections to investigate the nature of the resonance structure recently observed by the BESIII experiment in the $e^+e^- \to K^+ K^-$ cross section.

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arXiv2019

Search for $B^- \to Λ\bar p ν\barν$ with the BABAR experiment

We search for the rare flavor-changing neutral current process $B^- \to Λ{\overline p} ν{\overlineν}$ using data from the BABAR experiment. A total of 424 fb$^{-1}$ of $e^+e^-$ collision data collected at the center-of-mass energy of the $Υ$(4S) resonance is used in this study, corresponding to a sample of ${(471 \pm 3) \times 10^{6}}$ $B\overline{B}$ pairs. Signal $B^- \to Λ{\overline p} ν{\overlineν}$ candidates are identified by first fully reconstructing a $B^+$ decay in one of many possible exclusive decays to hadronic final states, then examining detector activity that is not associated with this reconstructed $B^+$ decay for evidence of a signal $B^- \to Λ{\overline p} ν{\overlineν}$ decay. The data yield is found to be consistent with the expected background contribution under a null signal hypothesis, resulting in an upper limit of ${{\cal B} (B^- \to Λ{\overline p} ν{\overlineν}) < 3.0\times 10^{-5}}$ at the $90\%$ confidence level.

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arXiv2018

Search for the decay mode $B^0\rightarrow p p \bar{p} \bar{p}$

A search is presented for the four-body decay $B^0\rightarrow p p \bar{p} \bar{p}$ in a sample of $471$ million $B\bar{B}$ pairs collected with the BaBar detector, operated at the SLAC PEP-II asymmetric-energy $e^+e^-$ collider. The center-of-mass energy is $10.58$ GeV. From a fit to the distribution of the energy-substituted mass $m_{\mathrm{ES}}$, the result $\mathcal{B}(B^0\rightarrow p p \bar{p} \bar{p})=(1.1 \pm 0.5 \pm 0.2) \times 10^{-7}$ is extracted, where the first uncertainty is statistical and the second is systematic. The significance of the signal is $2.9$ standard deviations. The upper limit on the branching fraction is determined to be $2.0 \times 10^{-7}$ at $90\%$ confidence level.

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arXiv2018

Study of the process $e^+e^- \to π^+π^-η$ using initial state radiation

We study the process $e^+e^- \to π^+π^-ηγ$, where the photon is radiated from the initial state. About 8000 fully reconstructed events of this process are selected from the BaBar data sample with an integrated luminosity of 469~fb$^{-1}$. Using the $π^+π^-η$ invariant mass spectrum we measure the $e^+e^- \to π^+π^-η$ cross section in the $e^+e^-$ center-of-mass energy range from 1.15 to 3.5 GeV. The cross section is well described by the Vector-Meson Dominance model with four $ρ$-like states. We observe $49\pm9$ events of the $J/ψ$ decay to $π^+π^-η$, and measure the product $Γ_{J/Ψ\to e^+e^-} \text{B}_{J/Ψ\to π^+π^-η} = 2.34 \pm 0.43_{\text{stat}} \pm 0.16_{\text{syst}}$~eV.

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arXiv2017

Measurement of the inclusive electron spectrum from B meson decays and determination of |Vub|

Based on the full BaBar data sample of 466.5 million BBbar pairs, we present measurements of the electron spectrum from semileptonic B meson decays. We fit the inclusive electron spectrum to distinguish Cabibbo-Kobayashi-Maskawa (CKM) suppressed B -> Xu e nu decays from the CKM-favored B -> Xc e nu decays, and from various other backgrounds, and determine the total semileptonic branching fraction BR(B -> X e nu) = (10.34 +- 0.04_stat +- 0.26_syst)%, averaged over B+- and B0 mesons. We determine the spectrum and branching fraction for charmless B -> Xu e nu decays and extract the CKM element |Vub|, by relying on four different QCD calculations based on the heavy quark expansion. While experimentally, the electron momentum region above 2.1GeV/c is favored, because the background is relatively low, the uncertainties for the theoretical predictions are largest in the region near the kinematic endpoint. Detailed studies to assess the impact of these four predictions on the measurements of the electron spectrum, the branching fraction, and the extraction of the CKM matrix element |Vub| are presented, with the lower limit on the electron momentum varied from 0.8GeV/c to the kinematic endpoint. We determine |Vub| using each of these different calculations and find, |Vub| = (3.794 +- 0.107_exp +0.292-0.219_SF +0.078-0.068_theory)*10^{-3} (De Fazio and Neubert), (4.563 +- 0.126_exp +0.230-0.208_SF +0.162-0.163_theory)*10^{-3} (Bosh, Lange, Neubert, and Paz), (3.959 +- 0.104_exp +0.164-0.154_SF +0.042-0.079_theory)*10^{-3} (Gambino, Giordano, Ossola, and Uraltsev), (3.848 +- 0.108_exp +0.084-0.070_theory)*10^{-3} (dressed gluon exponentiation), where the stated uncertainties refer to the experimental uncertainties of the partial branching fraction measurement, the shape function parameters, and the theoretical calculations.

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arXiv2017

Measurement of the $e^+e^-\to K^0_{\scriptscriptstyle S}K^\pmπ^{\mp}π^0$ and $K^0_{\scriptscriptstyle S}K^\pmπ^\mpη$ cross sections using initial-state radiation

The processes $e^+e^-\to K^0_{\scriptscriptstyle S}K^\pmπ^{\mp}π^0$ and $e^+e^-\to K^0_{\scriptscriptstyle S}K^\pmπ^{\mp}η$ are studied over a continuum of energies from threshold to 4 GeV with the initial-state photon radiation method. Using 454 fb$^{-1}$ data collected with the BABAR detector at the SLAC PEP-II storage ring, the first measurements of the cross sections for these processes are obtained. The intermediate resonance structures from $K^{*0}(Kπ)^0$, $K^{*}(892)^\pm(Kπ)^\mp$ and $K^0_{\scriptscriptstyle S}K^\pmρ^{\mp}$ are studied. The $J/ψ$ is observed in all of these channels, and corresponding branching fractions are measured.

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arXiv2016

Constraints on Axion couplings from the CDEX-1 experiment at the China Jinping Underground Laboratory

We report the results of searches for solar axions and galactic dark matter axions or axion-like particles with CDEX-1 experiment at the China Jinping Underground Laboratory, using 335.6 kg-days of data from a p-type point-contact germanium detector. The data are compatible with the background model and no excess signals are observed. Limits of solar axions on the model independent coupling $g_{Ae}<2.5\times10^{-11}$ from Compton, bremsstrahlung, atomic-recombination and deexcitation channel and $g^{\text{eff}}_{AN}\times g_{Ae}<6.1\times10^{-17}$ from $^{57}$Fe M1 transition at 90 % confidence level are derived. Within the framework of the DFSZ and KSVZ models, our results exclude the axion mass heavier than 0.9 eV/c$^{2}$ and 173 eV/c$^{2}$, respectively. The derived constraints for dark matter axions below 1 keV improves over the previous results.

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arXiv2016

Measurement of the B^0 -> D^*- pi^+ pi^- pi^+ branching fraction

Using a sample of (470.9 +- 2.8) x 10^6 BB-bar pairs, we measure the decay branching fraction B(B^0 -> D^*- pi^+ pi^- pi^+) = (7.26 +- 0.11 +- 0.31) x 10^-3, where the first uncertainty is statistical and the second is systematic. Our measurement will be helpful in studies of lepton universality by measuring B(B^0 -> D^*- tau^+ nu_tau) using tau^+ -> pi^+ pi^- pi^+ nu-bar_tau decays, normalized to B(B^0 -> D^*- pi^+ pi^- pi^+.

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arXiv2016

Measurement of the neutral $D$ meson mixing parameters in a time-dependent amplitude analysis of the $D^0\toπ^+π^-π^0$ decay

We measure the $D^0 - {\bar{D}}^0$ mixing parameters using a time-dependent amplitude analysis of the decay $D^0\toπ^+π^-π^0$. The data were recorded with the BABAR detector at center-of-mass energies at and near the $Υ(4S)$ resonance, and correspond to an integrated luminosity of approximately 468.1 ${\rm fb}^{-1}$. The neutral $D$ meson candidates are selected from $D^{*}(2010)^+\to D^0 π_s^+$ decays where the flavor at the production is identified by the charge of the low momentum pion, $π_s^+$. The measured mixing parameters are $x = (1.5\pm1.2\pm0.6) \%$ and $y = (0.2\pm0.9\pm0.5) \%$, where the quoted uncertainties are statistical and systematic, respectively.

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arXiv2016

Search for a muonic dark force at BABAR

Many models of physics beyond the Standard Model predict the existence of new Abelian forces with new gauge bosons mediating interactions between "dark sectors" and the Standard Model. We report a search for a dark boson Z' coupling only to the second and third generations of leptons in the reaction e+e- -> mu+mu- Z', Z' -> mu+mu- using 514 fb-1 of data collected by the BABAR experiment. No significant signal is observed for Z' masses in the range 0.212 - 10 GeV. Limits on the coupling parameter g' as low as 7x10^-4 are derived, leading to improvements in the bounds compared to those previously derived from neutrino experiments.

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