We report a measurement of the $e^+e^- \to \pi^+\pi^-\pi^0$ cross section in the energy range from 0.62 to 3.50 GeV using an initial-state radiation technique. We use an $e^+e^-$ data sample corresponding to 191 $\text{fb}^{-1}$ of integrated luminosity, collected at a center-of-mass energy at or near the $\Upsilon{(4S)}$ resonance with the Belle II detector at the SuperKEKB collider. Signal yields are extracted by fitting the two-photon mass distribution in $e^+e^- \to \pi^+\pi^-\pi^0\gamma$ events, which involve a $\pi^0 \to \gamma\gamma$ decay and an energetic photon radiated from the initial state. Signal efficiency corrections with an accuracy of 1.6% are obtained from several control data samples. The uncertainty on the cross section at the $\omega$ and $\phi$ resonances is dominated by the systematic uncertainty of 2.2%. The resulting cross sections in the 0.62-1.80 GeV energy range yield $ a_\mu^{3\pi} = [48.91 \pm 0.23~(\mathrm{stat}) \pm 1.07~(\mathrm{syst})] \times 10^{-10} $ for the leading-order hadronic vacuum polarization contribution to the muon anomalous magnetic moment. This result differs by $2.5$ standard deviations from the most precise current determination.
Energy bin range ($\sqrt{s'}$), number of events after unfolding ($N_{\mathrm{unf}}$), corrected efficiency ($\varepsilon$), and cross section ($\sigma_{3\pi}$) for $e^{+}e^{-} \to \pi^{+} \pi^{-} \pi^{0}$ in energy range 0.62--1.05~GeV. The two uncertainties in the cross section are the statistical and systematic contributions. The statistical uncertainties for the unfolding and cross section are square roots of the diagonal components of the unfolding covariance matrix. The image shows Figure 23 in the PRD paper, and the points with error bars indicate the cross section in the table.
Energy bin range ($\sqrt{s'}$), number of events after unfolding ($N_{\mathrm{unf}}$), corrected efficiency ($\varepsilon$), and cross section ($\sigma_{3\pi}$) for $e^{+}e^{-} \to \pi^{+} \pi^{-} \pi^{0}$ in energy range 1.05--3.50~GeV. The two uncertainties in the cross section are the statistical and systematic contributions. The statistical uncertainties for the unfolding and cross section are square roots of the diagonal components of the unfolding covariance matrix. The image shows Figure 23 in the PRD paper, and the points with error bars indicate the cross section in the table.
The statistic covariance matrix for the $e^+e^- \to \pi^+ \pi^- \pi^0$ cross section measurement at the Belle II. The 212 x 212 matrix of the energy ranges from 0.62 to 3.50 GeV. This covariance matrix, obtained by propagating the covariance matrix in the unfolding procedure, shows the total statistical uncertainties for the cross section results.
Measurements of the production cross-sections of the Standard Model (SM) Higgs boson ($H$) decaying into a pair of $\tau$-leptons are presented. The measurements use data collected with the ATLAS detector from $pp$ collisions produced at the Large Hadron Collider at a centre-of-mass energy of $\sqrt{s}=13\,\text{TeV}$, corresponding to an integrated luminosity of $139\,\text{fb}^{-1}$. Leptonic ($\tau\to\ell\nu_{\ell}\nu_{\tau}$) and hadronic ($\tau\to\text{hadrons}~\nu_{\tau}$) decays of the $\tau$-lepton are considered. All measurements account for the branching ratio of $H\to\tau\tau$ and are performed with a requirement $|y_H|<2.5$, where $y_H$ is the true Higgs boson rapidity. The cross-section of the $pp\to H\to\tau\tau$ process is measured to be $2.94 \pm 0.21 \text{(stat)} ^{+\,0.37}_{-\,0.32} \text{(syst)}$ pb, in agreement with the SM prediction of $3.17\pm0.09~ \mbox{pb}$. Inclusive cross-sections are determined separately for the four dominant production modes: $2.65 \pm 0.41 \text{(stat)} ^{+\,0.91}_{-\,0.67} \text{(syst)}$ pb for gluon$-$gluon fusion, $0.197 \pm 0.028 \text{(stat)} ^{+\,0.032}_{-\,0.026} \text{(syst)}$ pb for vector-boson fusion, $0.115 \pm 0.058 \text{(stat)} ^{+\,0.042}_{-\,0.040} \text{(syst)}$ pb for vector-boson associated production, and $0.033 \pm 0.031 \text{(stat)} ^{+\,0.022}_{-\,0.017} \text{(syst)}$ pb for top-quark pair associated production. Measurements in exclusive regions of the phase space, using the simplified template cross-section framework, are also performed. All results are in agreement with the SM predictions.
Observed yields in the boost_0_1J signal region category of the hh channel.
Observed yields in the boost_0_ge2J signal region category of the hh channel.
Observed yields in the boost_1_1J signal region category of the hh channel.
Using the KEDR detector at the VEPP-4M $e^+e^-$ collider, we have measured the values of $R_{\text{uds}}$ and $R$ at seven points of the center-of-mass energy between 3.12 and 3.72 GeV. The total achieved accuracy is about or better than $3.3\%$ at most of energy points with a systematic uncertainty of about $2.1\%$. At the moment it is the most accurate measurement of $R(s)$ in this energy range.
Measured values of $R_{\rm{uds}}(s)$ and $R(s)$ with statistical and systematic uncertainties.
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No description provided.
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THE ASYMMETRY SIGMA HAS BEEN DETERMINED BY THE FORMULA: D(SIG)/D(OMEGA)=D(SIG0)/D(OMEGA)*(1+P*SIGMA*COS(PHI)), WHERE D(SIG0)/D(OMEGA) - CROSS SECTION ON U NPOLARIZED PHOTON BEAM, P - BEAM POLARIZATION, PHI - ASIMUTHAL ANGLE BETWEEN POLARIZATION VECTOR OF BEAM AND THE PLANE OF THE REACTION.
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RE/IM MEASUREMENTS TAKEN FROM TABLE 1 OF KIRILLOVA 65.
TABLE 1 (REF. 1 ).
RE/IM MEASUREMENTS TAKEN FROM TABLE 1 OF KIRILLOVA 65.
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Axis error includes +- 0.0/0.0 contribution (?////).
Axis error includes +- 0.0/0.0 contribution (?////).
Axis error includes +- 0.0/0.0 contribution (?////).
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No description provided.
A first measurement is presented of exclusive photoproduction of $\rho^0$ mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years $2006$ and $2007$ at a centre-of-mass energy of $\sqrt{s}=319$ GeV and correspond to an integrated luminosity of $1.16$ pb$^{-1}$. The $\rho^0$ mesons with transverse momenta $p_T<1$ GeV are reconstructed from their decays to charged pions, while leading neutrons carrying a large fraction of the incoming proton momentum, $x_L>0.35$, are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality $Q^2 < 2$ GeV$^2$, the total energy of the photon-proton system $20 < W_{\gamma p} < 100$ GeV and the polar angle of the leading neutron $\theta_n < 0.75$ mrad. The cross section of the reaction $\gamma p \to \rho^0 n \pi^+$ is measured as a function of several variables. The data are interpreted in terms of a double peripheral process, involving pion exchange at the proton vertex followed by elastic photoproduction of a $\rho^0$ meson on the virtual pion. In the framework of one-pion-exchange dominance the elastic cross section of photon-pion scattering, $\sigma^{\rm el}(\gamma\pi^+ \to \rho^0\pi^+)$, is extracted. The value of this cross section indicates significant absorptive corrections for the exclusive reaction $\gamma p\to\rho^0 n \pi^+$.
The $\gamma p$ cross section integrated in the domain $0.35 < x_L < 0.95$ and $-t^\prime < 1$~GeV$^2$ and averaged over the energy range $20 < W_{\gamma p} < 100$ GeV for two intervals of leading neutron transverse momentum.
Differential photoproduction cross sections ${\rm d}\sigma_{\gamma p}/{\rm d}x_L$ for the exclusive process $\gamma p \to \rho^0 n \pi^+$ in two regions of neutron transverse momentum and $20 < W_{\gamma p} < 100$ GeV. The statistical, uncorrelated and correlated systematic uncertainties, $\delta_{stat}$, $\delta_{sys}^{unc}$ and $\delta_{sys}^{cor}$ respectively, are given, which does not include the global normalisation error of $4.4\%$.
Double differential photoproduction cross sections ${\rm d^2}\sigma_{\gamma p}/{\rm d}x_L{\rm d}p_{T,n}^2$ in the range $20 < W_{\gamma p} < 100$ GeV. The statistical, uncorrelated and correlated systematic uncertainties, $\delta_{stat}$, $\delta_{sys}^{unc}$ and $\delta_{sys}^{cor}$ respectively, are given, which does not include the global normalisation error of $4.4\%$.
The simultaneous production of pion resonances and strange particles was investigated. The simultaneous production of p 0 mesons and A-K pairs was observed in events characterized by charged particle multiplicity ns = 4 and having cross sections upo = 20 ± 8 ~b. Cross sections for the production of w and YJ resonances are presented. The 1340-MeV peak in the distribution of four-pion effective masses is discussed.
No description provided.
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