The Beam Conditions Monitor of the LHCb Experiment

The LHCb experiment at the European Organization for Nuclear Research (CERN) is dedicated to precision measurements of CP violation and rare decays of B hadrons. Its most sensitive components are protected by means of a Beam Conditions Monitor (BCM), based on polycrystalline CVD diamond sensors. Its configuration, operation and decision logics to issue or remove the beam permit signal for the Large Hadron Collider (LHC) are described in this paper.Comment: Index Terms: Accelerator measurement systems, CVD, Diamond, Radiation detector

The MADP Toolbox: An Open-Source Library for Planning and Learning in (Multi-)Agent Systems

This article describes the MultiAgent Decision Process (MADP) toolbox, a software library to support planning and learning for intelligent agents and multiagent systems in un- certain environments. Some of its key features are that it sup- ports partially observable environments and stochastic tran- sition models; has unified support for single- and multiagent systems; provides a large number of models for decision- theoretic decision making, including one-shot decision mak- ing (e.g., Bayesian games) and sequential decision mak- ing under various assumptions of observability and coopera- tion, such as Dec-POMDPs and POSGs; provides tools and parsers to quickly prototype new problems; provides an ex- tensive range of planning and learning algorithms for single- and multiagent systems; and is written in C++ and designed to be extensible via the object-oriented paradigm

Determination of the Michel Parameters rho, xi, and delta in tau-Lepton Decays with tau --> rho nu Tags

Using the ARGUS detector at the $e^+ e^-$ storage ring DORIS II, we have measured the Michel parameters $\rho$, $\xi$, and $\xi\delta$ for $\tau^{\pm}\to l^{\pm} \nu\bar\nu$ decays in $\tau$-pair events produced at center of mass energies in the region of the $\Upsilon$ resonances. Using $\tau^\mp \to \rho^\mp \nu$ as spin analyzing tags, we find $\rho_{e}=0.68\pm 0.04 \pm 0.08$, $\xi_{e}= 1.12 \pm 0.20 \pm 0.09$, $\xi\delta_{e}= 0.57 \pm 0.14 \pm 0.07$, $\rho_{\mu}= 0.69 \pm 0.06 \pm 0.08$, $\xi_{\mu}= 1.25 \pm 0.27 \pm 0.14$ and $\xi\delta_{\mu}= 0.72 \pm 0.18 \pm 0.10$. In addition, we report the combined ARGUS results on $\rho$, $\xi$, and $\xi\delta$ using this work und previous measurements.Comment: 10 pages, well formatted postscript can be found at http://pktw06.phy.tu-dresden.de/iktp/pub/desy97-194.p

Improved performance of the LHCb Outer Tracker in LHC Run 2

The LHCb Outer Tracker is a gaseous detector covering an area of $5\times 6 m^2$ with 12 double layers of straw tubes. The performance of the detector is presented based on data of the LHC Run 2 running period from 2015 and 2016. Occupancies and operational experience for data collected in $p p$, pPb and PbPb collisions are described. An updated study of the ageing effects is presented showing no signs of gain deterioration or other radiation damage effects. In addition several improvements with respect to LHC Run 1 data taking are introduced. A novel real-time calibration of the time-alignment of the detector and the alignment of the single monolayers composing detector modules are presented, improving the drift-time and position resolution of the detector by 20\%. Finally, a potential use of the improved resolution for the timing of charged tracks is described, showing the possibility to identify low-momentum hadrons with their time-of-flight.Comment: 29 pages, 20 figures, minor changes to match the published versio

Observation of the Isospin-Violating Decay Ds∗+→Ds+π0D_s^{*+}\to D_s^+\pi^0

Using data collected with the CLEO~II detector, we have observed the isospin-violating decay $D_s^{*+}\to D_s^+\pi^0$. The decay rate for this mode, relative to the dominant radiative decay, is found to be $\Gamma(D_s^{*+}\to D_s^+\pi^0)/\Gamma(D_s^{*+}\to D_s^+\gamma)= 0.062^{+0.020}_{-0.018}\pm0.022$.Comment: 8 page uuencoded postscript file, also available through http://w4.lns.cornell.edu/public/CLN

Frequencies of circulating MAIT cells are diminished in chronic hCV, HIV and HCV/ HIV Co-Infection and do not recover during therapy

Objective Mucosal-associated invariant T (MAIT) cells comprise a subpopulation of T cells that can be activated by bacterial products and cytokines to produce IFN-γ. Since little is known on MAIT cells during HCV infection, we compared their phenotype and function in comparison to HIV and HCV/HIV co-infected patients, and determined the effect of IFN-α-based and direct-acting antiviral therapy on MAIT cells of HCV patients. Methods Blood samples from patients with chronic HCV (CHCV), virologically suppressed HIV, acute HCV/HIV co-infection (AHCV/HIV) and healthy individuals were examined by flowcytometry for phenotype and function of MAIT and NK cells. Results and Conclusions Compared to healthy individuals, the frequency of CD161+ Vα7.2+ MAIT cells was significantly decreased in patients with CHCV, HIV and AHCV/HIV co-infection. CD38 expression on MAIT cells was increased in AHCV/HIV patients. MAIT cells were responsive to IFN-α in vitro as evidenced by enhanced frequencies of IFN-γ producing cells. IFN-α-based therapy for CHCV decreased the frequency of IFN-γ+ MAIT cells, which was still observed 24 weeks after successful therapy. Importantly, even after successful IFN-α-based as well as IFN-αfree therapy for CHCV, decreased frequencies of MAIT cells persisted. We show that the frequencies of MAIT cells are reduced in blood of patients with CHCV, HIV and in AHCV/ HIV co-infection compared to healthy individuals. Successful therapy for CHCV did not normalize MAIT cell frequencies at 24 weeks follow up. The impact of HIV and HCV infection on the numbers and function of MAIT cells warrant further studies on the impact of viral

Measurement of CP Asymmetries and Branching Fractions in Charmless Two-Body B-Meson Decays to Pions and Kaons

We present improved measurements of CP-violation parameters in the decays $B^0 \to \pi^+ \pi^-$, $B^0 \to K^+ \pi^-$, and $B^0 \to \pi^0 \pi^0$, and of the branching fractions for $B^0 \to \pi^0 \pi^0$ and $B^0 \to K^0 \pi^0$. The results are obtained with the full data set collected at the $\Upsilon(4S)$ resonance by the BABAR experiment at the PEP-II asymmetric-energy $B$ factory at the SLAC National Accelerator Laboratory, corresponding to $467 \pm 5$ million $B\bar B$ pairs. We find the CP-violation parameter values and branching fractions $S_{\pi^+\pi^-} = -0.68 \pm 0.10 \pm 0.03, C_{\pi^+\pi^-} = -0.25 \pm 0.08 \pm 0.02, A_{K^-\pi^+} = -0.107 \pm 0.016 ^{+0.006}_{-0.004}, C_{\pi^0\pi^0} = -0.43 \pm 0.26 \pm 0.05, Br(B^0 \to \pi^0 \pi^0) = (1.83 \pm 0.21 \pm 0.13) \times 10^{-6}, Br(B^0 \to K^0 \pi^0) = (10.1 \pm 0.6 \pm 0.4) \times 10^{-6},$ where in each case, the first uncertainties are statistical and the second are systematic. We observe CP violation with a significance of 6.7 standard deviations for $B^0 \to\pi^+\pi^-$ and 6.1 standard deviations for $B^0 \to K^+ \pi^-$, including systematic uncertainties. Constraints on the Unitarity Triangle angle $\alpha$ are determined from the isospin relations among the $B \to \pi\pi$ rates and asymmetries. Considering only the solution preferred by the Standard Model, we find $\alpha$ to be in the range $[71^\circ,109^\circ]$ at the 68% confidence level.Comment: 18 pages, 11 postscript figures, submitted to Phys. Rev.

Measurement of the Time-Dependent CP Asymmetry of Partially Reconstructed B0->D*+D*- Decays

We present a new measurement of the time-dependent CP asymmetry of B0->D*+D*- decays using (471+-5) million BBbar pairs collected with the BaBar detector at the PEP-II B Factory at the SLAC National Accelerator Laboratory. Using the technique of partial reconstruction, we measure the time-dependent CP asymmetry parameters S=-0.34+-0.12+-0.05$ and C=+0.15+-0.09+-0.04. Using the value for the CP-odd fraction R_perp=0.158+-0.028+-0.006, previously measured by BaBar with fully reconstructed B0->D*+D*- events, we extract the CP-even components S+=-0.49+-0.18+-0.07+-0.04 and C+=+0.15+-0.09+-0.04. In each case, the first uncertainty is statistical and the second is systematic; the third uncertainty on S+ is the contribution from the uncertainty on R_perp. The measured value of the CP-even component S+ is consistent with the value of sin(2Beta) measured in b->(ccbar)s transitions, and with the Standard Model expectation of small penguin contributions.Comment: 17 pages, 7 figures, submitted to Physical Review

Search for lepton-number violating processes in B+ -> h- l+ l+ decays

We have searched for the lepton-number violating processes B+ -> h- l+ l+ with h- = K-/pi- and l+ = e+/mu+, using a sample of 471+/-3 million BBbar events collected with the BaBar detector at the PEP-II e+e- collider at the SLAC National Accelerator Laboratory. We find no evidence for these decays and place 90% confidence level upper limits on their branching fractions Br(B+ -> pi- e+ e+) K- e+ e+) pi- mu+ mu+) K- mu+ mu+) < 6.7 x 10^{-8}.Comment: 8 pages, 4 postscript figures, submitted to Phys. Rev. D. R

Measurement of the branching fraction for Υ(1S)→τ+τ−\Upsilon (1S) \to \tau^+ \tau^-

We have studied the leptonic decay of the $\Upsilon (1S)$ resonance into tau pairs using the CLEO II detector. A clean sample of tau pair events is identified via events containing two charged particles where exactly one of the particles is an identified electron. We find $B(\Upsilon(1S) \to \tau^+ \tau^-) = (2.61~\pm~0.12~{+0.09\atop{-0.13}})$. The result is consistent with expectations from lepton universality.Comment: 9 pages, RevTeX, two Postscript figures available upon request, CLNS 94/1297, CLEO 94-20 (submitted to Physics Letters B