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Production of charged pions, kaons and protons in e+e- annihilations into hadrons at sqrt{s} = 10.54 GeV

Inclusive production cross sections of $π^\pm$, $K^\pm$ and $p\bar{p}$ per hadronic $e^+e^-$ annihilation event in $e^+e^-$ are measured at a center-of-mass energy of 10.54 GeV, using a relatively small sample of very high quality data from the BaBar experiment at the PEP-II $B$-factory at the SLAC National Accelerator Laboratory. The drift chamber and Cherenkov detector provide clean samples of identified $π^\pm$, $K^\pm$ and $p\bar{p}$ over a wide range of momenta. Since the center-of-mass energy is below the threshold to produce a $B\bar{B}$ pair, with $B$ a bottom-quark meson, these data represent a pure $e^+e^- \rightarrow q\bar{q}$ sample with four quark flavors, and are used to test QCD predictions and hadronization models. Combined with measurements at other energies, in particular at the $Z^0$ resonance, they also provide precise constraints on the scaling properties of the hadronization process over a wide energy range.

hep-ex

Pre-conceptual Design Assessment of DEMO Remote Maintenance

EDFA, as part of the Power Plant Physics and Technology programme, has been working on the pre-conceptual design of a Demonstration Power Plant (DEMO). As part of this programme, a review of the remote maintenance strategy considered maintenance solutions compatible with expected environmental conditions, whilst showing potential for meeting the plant availability targets. A key finding was that, for practical purposes, the expected radiation levels prohibit the use of complex remote handling operations to replace the first wall. In 2012/13, these remote maintenance activities were further extended, providing an insight into the requirements, constraints and challenges. In particular, the assessment of blanket and divertor maintenance, in light of the expected radiation conditions and availability, has elaborated the need for a very different approach from that of ITER. This activity has produced some very informative virtual reality simulations of the blanket segments and pipe removal that are exceptionally valuable in communicating the complexity and scale of the required operations. Through these simulations, estimates of the maintenance task durations have been possible demonstrating that a full replacement of the blankets within 6 months could be achieved. The design of the first wall, including the need to use sacrificial limiters must still be investigated. In support of the maintenance operations, a first indication of the requirements of an Active Maintenance Facility (AMF) has been elaborated.

physics.plasm-ph

Measurement of the B+ --> omega l+ nu branching fraction with semileptonically tagged B mesons

We report a measurement of the branching fraction of the exclusive charmless semileptonic decay B+ --> omega l+ nu, where l is either an electron or a muon. We use samples of B+ mesons tagged by a reconstructed charmed semileptonic decay of the other B meson in the event. The measurement is based on a dataset of 426.1 fb-1 of e+e- collisions at a center-of-mass energy of 10.58 GeV recorded with the BABAR detector at the PEP-II asymmetric-energy e+e- storage rings. We measure a branching fraction of BF(B+ --> omega l+ nu) = (1.35 +/- 0.21 +/- 0.11) x 10(-4), where the uncertainties are statistical and systematic, respectively. We also present measurements of the partial branching fractions in three bins of q2, the invariant-mass squared of the lepton-neutrino system, and we compare them to theoretical predictions of the form factors.

hep-ex

Measurement of the e+e- --> p anti-p cross section in the energy range from 3.0 to 6.5 GeV

The e+ e- --> p anti-p cross section and the proton magnetic form factor have been measured in the center-of-mass energy range from 3.0 to 6.5 GeV using the initial-state-radiation technique with an undetected photon. This is the first measurement of the form factor at energies higher than 4.5 GeV. The analysis is based on 469 fb-1 of integrated luminosity collected with the BABAR detector at the PEP-II collider at e+e- center-of-mass energies near 10.6 GeV. The branching fractions for the decays J/psi --> p anti-p and psi(2S) --> p anti-p have also been measured.

hep-ex

Search for a light Higgs boson decaying to two gluons or ss-bar in the radiative decays of Y(1S)

We search for the decay Y(1S) -> gamma A0, A0 -> gg or ss-bar, where A0 is the pseudoscalar light Higgs boson predicted by the next-to-minimal supersymmetric standard model. We use a sample of (17.6 +- 0.3)x 10^6 Y(1S) mesons produced in the BaBar experiment via e+e- -> Y(2S) -> pi+pi-Y(1S). We see no significant signal and set 90%-confidence-level upper limits on the product branching fraction B(Y(1S) -> gamma A0) x B(A0 -> gg or ss-bar) ranging from 10^-6 to 10^-2 for A0 masses in the range 0.5 to 9.0GeV/c^2.

hep-ex

Precision Measurement of the e+e- --> K+K-(gamma) Cross Section with the Initial-State Radiation Method at BaBar

A precise measurement of the cross section for the process e+e- --> K+K-(gamma) from threshold to an energy of 5 GeV is obtained with the initial-state radiation (ISR) method using 232 fb^{-1} of data collected with the BaBar detector at e+e- center-of-mass energies near 10.6 GeV. The measurement uses the effective ISR luminosity determined from the e+e- --> mu+mu-(gamma)gamma_ISR process with the same data set. The corresponding lowest-order contribution to the hadronic vacuum polarization term in the muon magnetic anomaly is found to be a_mu^{KK, LO}=(22.93 +- 0.18_{stat} +- 0.22_{syst}) * 10^{-10}. The charged kaon form factor is extracted and compared to previous results. Its magnitude at large energy significantly exceeds the asymptotic QCD prediction, while the measured slope is consistent with the prediction.

hep-ex

Study of the $K^+ K^-$ invariant-mass dependence of CP asymmetry in $B^+ \rightarrow K^+ K^- K^+$ decays

As a followup to the latest BABAR amplitude analysis of the decay $B^+ \rightarrow K^+ K^- K^+$, we investigate the $K^+ K^-$ invariant-mass dependence of the CP asymmetry and compare it to that obtained by the LHCb collaboration. The results are based on a data sample of approximately $470 \times 10^6 B\bar{B}$ decays, collected with the BABAR detector at the PEP-II asymmetric-energy $B$ factory at the SLAC National Accelerator Laboratory.

hep-ex

Search for Supersymmetry with Like-Sign Lepton-Tau Events at CDF

We present a search for chargino-neutralino associated production using like electric charge dilepton events collected by the CDF II detector at the Fermilab Tevatron in proton-antiproton collisions at $\sqrt{s} = 1.96$ TeV. One lepton is identified as the hadronic decay of a tau lepton, while the other is an electron or muon. In data corresponding to 6.0 fb$^{-1}$ of integrated luminosity, we obtain good agreement with standard model predictions, and set limits on the chargino-neutralino production cross section for simplified gravity- and gauge-mediated models. As an example, assuming that the chargino and neutralino decays to taus dominate, in the simplified gauge-mediated model we exclude cross sections greater than 300 fb at 95% credibility level for chargino and neutralino masses of 225 \gevcc. This analysis is the first to extend the LHC searches for electroweak supersymmetric production of gauginos to high $\tanβ$ and slepton next-to-lightest supersymmetric particle scenarios.

hep-ex

Time-Integrated Luminosity Recorded by the BABAR Detector at the PEP-II e+e- Collider

We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energy e+e- collider at the Upsilon(4S), Upsilon(3S) and Upsilon(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by counting e+e- --> e+e- and (for the Upsilon(4S) only) e+e- --> mu+mu- candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross sections of e+e- --> e+e- and e+e- --> mu+mu-, the statistical uncertainties of the measurement are substantially smaller than the systematic uncertainties. The dominant systematic uncertainties are due to observed differences between data and simulation, as well as uncertainties on the cross sections. For data collected on the Upsilon(3S) and Upsilon(2S) resonances, an additional uncertainty arises due to Upsilon --> e+e-X background. For data collected off the Upsilon resonances, we estimate an additional uncertainty due to time-dependent efficiency variations, which can affect the short off-resonance runs. The relative uncertainties on the luminosities of the on-resonance (off-resonance) samples are 0.43% (0.43%) for the Upsilon(4S), 0.58% (0.72%) for the Upsilon(3S), and 0.68% (0.88%) for the Upsilon(2S).

hep-ex

Combination of searches for the Higgs boson using the full CDF data set

We present a combination of searches for the standard model Higgs boson using the full CDF Run II data set, which corresponds to an integrated luminosity of 9.45--10.0 fb$^{-1}$ collected from $\sqrt{s}=1.96$ TeV $p{\bar{p}}$ collisions at the Fermilab Tevatron. The searches consider Higgs boson production from gluon-gluon fusion, vector-boson fusion, and associated production with either a $W$ or $Z$ boson or a $t{\bar{t}}$ pair. Depending on the production mode, Higgs boson decays to $W^+W^-$, $ZZ$, $b{\bar{b}}$, $τ^+τ^-$, and $γγ$ are examined. We search for a Higgs boson with masses ($m_H$) in the range 90--200 GeV/$c^2$. In the absence of a signal, we expect based on combined search sensitivity to exclude at the 95% credibility level the mass regions $90<m_H<94$ GeV/$c^2$, $96<m_H<106$ GeV/$c^2$, and $153<m_H<175$ GeV/$c^2$. The observed exclusion regions are $90<m_H<102$ GeV/$c^2$ and $149<m_H<172$ GeV/$c^2$. A moderate excess of signal-like events relative to the background expectation at the level of 2.0 standard deviations is present in the data for the $m_H=125$ GeV/$c^2$ search hypothesis. We also present interpretations of the data within the context of a fermiophobic model and an alternative standard model incorporating a fourth generation of fermions. Finally, for the hypothesis of a new particle with mass 125 GeV/$c^2$, we constrain the coupling strengths of the new particle to $W^\pm$ bosons, $Z$ bosons, and fermions.

hep-ex

Observation of direct CP violation in the measurement of the Cabibbo-Kobayashi-Maskawa angle gamma with B+- --> D(*)K(*)+- decays

We report the determination of the Cabibbo-Kobayashi-Maskawa CP-violating angle gamma through the combination of various measurements involving B^{+-} --> D K^{+-}, B^{+-} --> D^{*} K^{+-}, and B^{+-} --> D K^{*+-} decays performed by the BaBar experiment at the PEP-II e^{+}e^{-} collider at SLAC National Accelerator Laboratory. Using up to 474 million B\bar{B} pairs, we obtain gamma = (69 ^{+17}_{-16})^\circ (modulo 180^\circ). The total uncertainty is dominated by the statistical component, with the experimental and amplitude-model systematic uncertainties amounting to +-4^\circ. The corresponding two-standard-deviation region is 41^\circ < gamma < 102^\circ. This result is inconsistent with gamma = 0 with a significance of 5.9 standard deviations.

hep-ex

A Search for the Rare Decays B --> pi l+l- and B0 --> eta l+l-

We present the results of a search for the rare flavor-changing neutral-current decays B --> pi l+l- (pi=pi+/-, pi0 and l = e,mu) and B0 --> eta l+l- using a sample of e+e- --> Y(4S) BB decays decays corresponding to 428 fb^-1 of integrated luminosity collected by the BABAR detector. No significant signal is observed, and we set an upper limit on the isospin and lepton-flavor averaged branching fraction of BF(B --> pi l+l-) < 7.0 x 10^-8 and a lepton-flavor averaged upper limit of BF(B0 --> eta l+l-) < 9.2 x 10^-8, both at the 90% confidence level. We also report 90% confidence level branching fraction upper limits for the individual modes B+ --> pi+ e+e-, B0 --> pi0 e+e-, B+ --> pi+ mu+mu-, B0 --> pi0 mu+mu-, B0 --> eta e+e-, and B0 --> eta mu+mu-.

hep-ex

Measurement of an Excess of B -> D(*) Tau Nu Decays and Implications for Charged Higgs Bosons

Based on the full BaBar data sample, we report improved measurements of the ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B -> D(*) l Nu), where l is either e or mu. These ratios are sensitive to new physics contributions in the form of a charged Higgs boson. We measure R(D) = 0.440 +- 0.058 +- 0.042 and R(D*) = 0.332 +- 0.024 +- 0.018, which exceed the Standard Model expectations by 2.0 sigma and 2.7 sigma, respectively. Taken together, our results disagree with these expectations at the 3.4 sigma level. This excess cannot be explained by a charged Higgs boson in the type II two-Higgs-doublet model. Kinematic distributions presented here exclude large portions of the more general type III two-Higgs-doublet model, but there are solutions within this model compatible with the results.

hep-ex

Search for CP violation in the Decays $D^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$, $D_s^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$, and $D_s^{\pm}\to K^0_{\scriptscriptstyle S} π^\pm$

We report a search for CP violation in the decay modes $D^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$, $D_s^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$, and $D_s^{\pm}\to K^0_{\scriptscriptstyle S} π^\pm$ using a data set corresponding to an integrated luminosity of $469\,{\,fb}^{-1}$ collected with the {\slshape B\kern-0.1em{\smaller A}\kern-0.1em B\kern-0.1em{\smaller A\kern-0.2em R}} detector at the PEP-II asymmetric energy $e^+e^-$ storage rings. The decay rate CP asymmetries, $A_{CP}$, are determined to be $(+0.13 \pm 0.36 \stat \pm 0.25 \syst)%$, $(-0.05 \pm 0.23 \stat \pm 0.24 \syst)%$, and $(+0.6 \pm 2.0 \stat \pm 0.3 \syst)%$, respectively. These measurements are consistent with zero, and also with the standard model prediction ($(-0.332 \pm 0.006)%$ for the $D^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$ and $D_s^{\pm} \to K^0_{\scriptscriptstyle S} K^\pm$ modes, and $(+0.332 \pm 0.006)%$ for the $D_s^{\pm}\to K^0_{\scriptscriptstyle S} π^\pm$ mode). They are the most precise determinations to date.

hep-ex

Search for a Low-Mass Scalar Higgs Boson Decaying to a Tau Pair in Single-Photon Decays of Upsilon(1S)

We search for a low-mass scalar CP-odd Higgs boson, A0, produced in the radiative decay of the Upsilon resonance and decaying into a tau+tau- pair: Upsilon(1S)->gamma A0. The production of Upsilon(1S) mesons is tagged by Upsilon(2S)->pi+pi-Upsilon(1S) transitions, using a sample of (98.3+/-0.9) million Upsilon(2S) mesons collected by the BaBar detector. We find no evidence for a Higgs boson in the mass range 3.5 GeV<= m(A0)<=9.2 GeV, and combine these results with our previous search for the tau decays of the light Higgs in radiative Upsilon(3S) decays, setting limits on the coupling of A0 to the b/bbar quarks in the range 0.09-1.9. Our measurements improve the constraints on the parameters of the Next-to-Minimal-Supersymmetric Standard Model and similar theories with low-mass scalar degrees of freedom.

hep-ex

Measurement of D0-D0bar Mixing and CP Violation in Two-Body D0 Decays

We present a measurement of D0-D0bar mixing and CP violation using the ratio of lifetimes simultaneously extracted from a sample of D0 mesons produced through the flavor-tagged process D*+ -> D0 pi+, where D0 decays to K-+pi+-, K-K+, or pi-pi+, along with the untagged decays D0 -> K-+pi+- and D0 -> K-K+. The lifetimes of the CP-even, Cabibbo-suppressed modes K-K+ and pi-pi+ are compared to that of the CP-mixed mode K-+pi+- in order to measure yCP and DeltaY. We obtain yCP = [0.72 +- 0.18 (stat) +- 0.12 (syst)]% and DeltaY = [0.09 +- 0.26 (stat) +- 0.06 (syst)]%, where DeltaY constrains possible CP violation. The yCP result excludes the null mixing hypothesis at 3.3 sigma significance. This analysis is based on an integrated luminosity of 468 fb-1 collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider.

hep-ex

Search for the Decay D0 -> gamma gamma and Measurement of the Branching Fraction for D0 -> pi0 pi0

We search for the rare decay of the $D^{0}$ meson to two photons, $D^0 \rightarrow γγ$, and present a measurement of the branching fraction for a $D^0$ meson decaying to two neutral pions, ${B}(D^0 \rightarrow π^0 π^0)$. The data sample analyzed corresponds to an integrated luminosity of 470.5 {\sl B {-0.4em} {\small\sl A} {-0.37em} \sl B {-0.4em} {\small\sl A {-0.02em}R}} detector at the PEP-II asymmetric-energy $e^{+} e^{-}$ collider at SLAC. We place an upper limit on the branching fraction for the decay of a $D^0$ meson to two photons, ${B}(D^0 \rightarrow γγ) < 2.2 \times 10^{-6}$, at 90% confidence level, and find ${B}(D^0 \rightarrow π^0 π^0) = (8.4 \pm 0.1 \pm 0.4 \pm 0.3) \times 10^{-4}$.

hep-ex

Search for resonances decaying to eta_c pi+ pi- in two-photon interactions

We report a study of the process gamma gamma -> X -> eta_c pi+ pi-, where X stands for one of the resonances chi_{c2}(1P), eta_c(2S), X(3872), X(3915), or chi_{c2}(2P). The analysis is performed with a data sample of 473.9 fb^{-1} collected with the BaBar detector at the PEP-II asymmetric-energy electron-positron collider. We do not observe a significant signal for any channel, and calculate 90% confidence-level upper limits on the products of branching fractions and two-photon widths Gamma(X -> gamma gamma)BR(X -> eta_c pi+ pi-): 15.7 eV for chi_{c2}(1P), 133 eV for eta_c(2S), 11.1 eV for X(3872) (assuming it to be a spin-2 state), 16 eV for X(3915) (assuming it to be a spin-2 state), and 19 eV for chi_{c2}(2P). We also report upper limits on the ratios of branching fractions BR(eta_c(2S) -> eta_c pi+ pi-)/BR(eta_c(2S)-> K_S^0 K+ pi-) < 10.0 and BR(chi_{c2}(1P) -> eta_c pi+ pi-)/BR(chi_{c2}(1P)-> K_S^0 K+ pi-) <32.9 at the 90% confidence level.

hep-ex