The possibility of measuring the proton electromagnetic form factors in the time-like region at FAIR with the \PANDA detector is discussed. Detailed simulations on signal efficiency for the ...annihilation of $\bar p +p $ into a lepton pair as well as for the most important background channels have been performed. It is shown that precision measurements of the differential cross section of the reaction $\bar p +p \to e^++ e^-$ can be obtained in a wide angular and kinematical range. The individual determination of the moduli of the electric and magnetic proton form factors will be possible up to a value of momentum transfer squared of $q^2\simeq 14$ (GeV/c)$^2$. The total $\bar p +p\to e^++e^-$ cross section will be measured up to $q^2\simeq 28$ (GeV/c)$^2$. The results obtained from simulated events are compared to the existing data. Sensitivity to the two photons exchange mechanism is also investigated.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present a measurement of the time-dependent CP-violating asymmetries in $B^0 \to K^{*0}\gamma (K^{*0}\to K_S^0 \pi^0)$ decays based on 124 million $\Upsilon(4S)\to B^0\bar{B}^0$ decays collected ...with the BaBar detector at the PEP-II asymmetric-energy $B$ Factory at the Stanford Linear Accelerator Center. In a sample containing $105\pm 14$ signal decays, we measure $S_{K^{*0}} = 0.25 \pm 0.63 \pm 0.14$ and $S_{K^{*0}} = -0.57 \pm 0.32 \pm 0.09$, where the first error is statistical and the second systematic.
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The possibility of measuring the proton electromagnetic form factors in the time-like region at FAIR with the
ANDA detector is discussed. Detailed simulations on signal efficiency for the ...annihilation of
+
p
into a lepton pair as well as for the most important background channels have been performed. It is shown that precise measurements of the differential cross-section of the reaction
+
p
e
-
+
e
+
can be obtained in a wide kinematical range. The determination of the ratio
R
of the moduli of the electric and magnetic proton form factors will be possible up to a value of momentum transfer squared of
q
2
≃ 14 (GeV/
c
)^2 with absolute precision from 0.01 to 0.5 (for
R
∼ 1 . The total
+
p
e
-
+
e
+
cross-section will be measured up to
q
2
≃ 28 (GeV/
c
)^2. The results obtained from simulated events are compared to the existing data. Sensitivity to the two-photon exchange mechanism is also investigated.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present measurements of branching fractions and charge asymmetries for six B -meson decay modes with an η or η ′ meson in the final state. The data sample corresponds to 232 × 10 6 B ¯¯¯ B pairs ...collected with the BABAR detector at the PEP-II asymmetric-energy e + e − B Factory at SLAC. We measure the branching fractions (in units of 10 − 6 ): B ( B + → η π + ) = 5.1 ± 0.6 ± 0.3 , B ( B + → η K + ) = 3.3 ± 0.6 ± 0.3 , B ( B 0 → η K 0 ) = 1.5 ± 0.7 ± 0.1 ( < 2.5 at 90% C.L.), B ( B + → η ρ + ) = 8.4 ± 1.9 ± 1.1 , B ( B 0 → η ω ) = 1.0 ± 0.5 ± 0.2 ( < 1.9 at 90% C.L.), and B ( B + → η ′ π + ) = 4.0 ± 0.8 ± 0.4 , where the first uncertainty is statistical and second systematic. For the charged modes we also determine the charge asymmetries, all found to be compatible with zero.
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We search for the factorization-suppressed decays B → χ c 0 K ( * ) and B → χ c 2 K ( * ) , with χ c 0 and χ c 2 decaying into J / ψ γ , using a sample of 124 × 10 6 B ¯¯¯ B events collected with the ...BABAR detector at the PEP-II storage ring of the Stanford Linear Accelerator Center. We find no significant signal and set upper bounds for the branching fractions.
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Using a data sample corresponding to an integrated luminosity of 342 $fb^{-1}$ collected with the BABAR detector at the SLAC PEP-II electron-positron storage ring operating at a center-of-mass energy ...near 10.58 GeV, we measure ${\cal{B}} (\tau^- \to \pi^- \pi^- \pi^+ \nu_\tau) = (8.83 \pm 0.01 \pm 0.13) %$, ${\cal{B}} (\tau^- \to K^- \pi^- \pi^+ \nu_\tau) = (0.273\pm 0.002\pm 0.009)%$, ${\cal{B}} (\tau^- \to K^- \pi^- K^+ \nu_\tau) = (0.1346\pm 0.0010 \pm 0.0036)%$ and ${\cal{B}} (\tau^- \to K^- K^- K^+ \nu_\tau) = (1.58\pm 0.13 \pm 0.12)\times 10^{-5}$, where the uncertainties are statistical and systematic, respectively. Events where the $\pi^+\pi^-$ pair is consistent with coming from a $K^0_S$ are excluded. These are significant improvements over previous measurements, with the ${\cal{B}} (\tau^- \to K^- K^- K^+ \nu_\tau)$ result being the first resonant plus non-resonant measurement of this mode. We also report a first measurement of ${\cal{B}} (\tau^- \to \phi\pi^- \nu_\tau) = (3.42\pm 0.55 \pm 0.25)\times 10^{-5}$ and a new measurement of ${\cal{B}} (\tau^- \to \phi K^- \nu_\tau) = (3.39\pm 0.20 \pm 0.28)\times 10^{-5}$.
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