Posters

Ostatnio dodane:
2017-06-12
14:12
CDSLabs: Towards the Next Generation CERN Institutional Repository
 Reference: Poster-2017-589 Keywords:  Collaborative tools  Invenio  CDS  CERN Document Server  Institutional Repository Created: 2016. -1 p Creator(s): Marian, Ludmila; Gabancho, Esteban; Tzovanakis, Harris; Witowski, Sebastian CERN Document Server (CDS) is the CERN Institutional Repository, playing a key role in the storage, dissemination and archival for all research material published at CERN, as well as multimedia and some administrative documents. As the CERN’s document hub, it joins together submission and publication workflows dedicated to the CERN experiments, but also to the video and photo teams, to the administrative groups, as well as outreach groups. In the past year, Invenio, the underlying software platform for CDS, has been undergoing major changes, transitioning from a digital library system to a digital library framework, and moving to a new software stack (Invenio is now built on top of the Flask web development framework, using Jinja2 template engine, SQLAlchemy ORM, JSONSchema data model, and Elasticsearch for information retrieval). In order to reflect these changes on CDS, we are launching a parallel service, CDSLabs, with the goal of offering our users a continuous view of the reshaping of CDS, as well as increasing the feedback from the community in the development phase, rather than after release. © CERN Geneva Access to files

2017-05-22
12:08
Measurements of charm mixing and $CP$ violation using $D^0 \to K^\pm \pi^\mp$ decays
 Reference: Poster-2017-588 Keywords:  LHCb Created: 2017. -1 p Creator(s): Davis, Adam Measurements of charm mixing and $CP$ violation parameters from the decay-time-dependent ratio of $D^0 \to K^+ \pi^-$ to $D^0 \to K^- \pi^+$ decay rates and the charge-conjugate ratio are reported. The analysis uses $\overline{B}\to D^{*+} \mu^- X$, and charge-conjugate decays, where $D^{*+}\to D^0\pi^+$, and $D^0\to K^{\mp} \pi^{\pm}$. The $pp$ collision data are recorded by the \lhcb experiment at center-of-mass energies $\sqrt{s}$ = 7 and 8 TeV corresponding to an integrated luminosity of 3~fb$^{-1}$ The data are analyzed under three hypotheses: (i) mixing assuming $CP$ symmetry, (ii) mixing assuming no direct $CP$ violation in the Cabibbo-favored or doubly Cabibbo-suppressed decay amplitudes, and (iii) mixing allowing either direct $CP$ violation and/or $CP$ violation in the superpositions of flavor eigenstates defining the mass eigenstates. The data are also combined with those from a previous LHCb study of $D^0\to K \pi$ decays from a disjoint set of $D^{*+}$ candidates produced directly in $pp$ collisions. In all cases, the data are consistent with the hypothesis of $CP$ symmetry. Related links:LHCP2017 © CERN Geneva Access to files

2017-05-22
11:34
Measurements of the $CP$ violating phase $\phi_s$ at LHCb
 Reference: Poster-2017-587 Keywords:  LHCb Created: 2017. -1 p Creator(s): Wang, Mengzhen The measurement of the mixing-induced CP-violating phase $\phi_s$ in the Bs-Bsbar system is one of the key goals of the LHCb experiment. It has been measured at LHCb exploiting the Run I data set and using several decay channels. The poster shows the most recent results obtained analyzing $B_s^0 \to J/\psi K^+K^-$ candidates in the mass region above the $\phi(1020)$ resonance. The poster also shows previous measurements obtained analyzing the golden channel, $B_s^0 \to J/\psi K^+K^-$ in $\phi(1020)$ region, and $B_s^0 \to J/\psi \pi^+ \pi^-$. Finally, a combination of those studies is presented. Related links:LHCP2017 © CERN Geneva Access to files

2017-03-10
15:58
Expanding Model Independent Approaches for Measuring the CKM angle $\gamma$ at LHCb
 Reference: Poster-2017-586 Created: 2017. -1 p Creator(s): Prouve, Claire Model independent approaches to measuring the CKM angle $\gamma$ in $B\rightarrow DK$ decays at LHCb are explored. In particular, we consider the case where the $D$ meson decays into a final state with four hadrons. Using four-body final states such as $\pi^+ \pi^- \pi^+ \pi^-$, $K^+ \pi^- \pi^+ \pi^-$ and $K^+ K^- \pi^+ \pi^-$ in addition to traditional 2 and 3 body states and has the potential to significantly improve to the overall constraint on $\gamma$. There is a significant systematic uncertainty associated with modelling the complex phase of the $D$ decay amplitude across the five-dimensional phase space of the four body decay. It is therefore important to replace these model-dependent quantities with model-independent parameters as input for the $\gamma$ measurement. These model independent parameters have been measured using quantum-correlated $\psi(3770) \rightarrow D^0 \overline{D^0}$ decays collected by the CLEO-c experiment, and, for $D\rightarrow K^+ \pi^- \pi^+ \pi^-$, with $D^0-\overline{D^0}$ mixing at LHCb. This poster will give a brief overview the status and prospects of $\gamma$ measurements with $B\rightarrow DK$, $D\rightarrow$ 4-body using a combination of LHCb and charm factory data, with focus on the $D$ meson decays to four pions. Related links:LHCC Poster Session © CERN Geneva Access to files

2017-03-08
15:28
Laser photodetachment of radioactive ions: towards the determination of the electronegativity of astatine
 Reference: Poster-2017-585 Created: 2017. -1 p Creator(s): Rothe, Sebastian; Sundberg, Julia; Welander, Jakob Emanuel; Chrysalidis, Katerina; Day Goodacre, Thomas [...] Negatively charged ions are mainly stabilized through the electron correlation effect. A measure of the stability of a negative ion is the electron affinity, which the energy gain by attaching an electron to a neutral atom. This fundamental quantity is, due to the almost general lack of bound excited states, the only atomic property that can be determined with high accuracy for negative ions. We will present the results of the first laser photodetachment studies of radioactive negative ions at CERN-ISOLDE. The photodetachment threshold for the radiogenic iodine isotope 128I was measured successfully, demonstrating the performance of the upgraded GANDALPH experimental beam line. The first detection of photo-detached astatine atoms marks a milestone towards the determination of the EA of this radioactive element. © CERN Geneva Access to files

2017-03-03
10:13
A stand-alone track reconstruction algorithm for the scintillating fibre tracker at the LHCb upgrade
 Reference: Poster-2017-584 Created: 2017. -1 p Creator(s): Quagliani, Renato The LHCb upgrade detector project foresees the presence of a scintillating fiber tracker (SciFi) to be used during the LHC Run III, starting in 2020. The instantaneous luminosity will be increased up to $2\times10^{33}$, five times larger than in Run II and a full software event reconstruction will be performed at the full bunch crossing rate by the trigger. The new running conditions, and the tighter timing constraints in the software trigger, represent a big challenge for track reconstruction. This poster presents the design and performance of a novel algorithm that has been developed to reconstruct track segments using solely hits from the SciFi. This algorithm is crucial for the reconstruction of tracks originating from long-lived particles such as $K_{S}^{0}$ and $\Lambda$ and allows to greatly enhance the physics potential and capabilities of the LHCb upgrade when compared to its previous implementation. Related links:LHCC Poster Session © CERN Geneva Access to file

2017-03-03
10:10
Measurement of matter-antimatter differences in beauty baryon decays at LHCb
 Reference: Poster-2017-583 Created: 2017. -1 p Creator(s): Merli, Andrea Differences in the behaviour of matter and antimatter have been observed in $K$ and $B$ meson decays, but not yet in any baryon decay. Such differences are associated with the non-invariance of fundamental interactions under the combined charge-conjugation and parity transformations, known as $C\!P$ violation. Using data from the LHCb experiment at the Large Hadron Collider, a search is made for $C\!P$-violating asymmetries in the decay angle distributions of $\Lambda_b^0$ baryons decaying to $p\pi^-\pi^+\pi^-$ and $p\pi^-K^+K^-m$ final states. These four-body hadronic decays are a promising place to search for sources of $C\!P$ violation both within and beyond the Standard Model of particle physics. We find evidence for $C\!P$ violation in $\Lambda_b^0$ to $p\pi^-\pi^+\pi^-$ decays with a statistical significance corresponding to 3.3 standard deviations including systematic uncertainties. This represents the first evidence for $C\!P$ violation in the baryon sector. Related links:LHCC Poster Session © CERN Geneva Access to files

2017-03-03
10:07
Prospects for $D^{0} \rightarrow h^+h^- \mu^+ \mu^-$ $(h=K,\pi)$ decays at LHCb
 Reference: Poster-2017-582 Created: 2017. -1 p Creator(s): Mitzel, Dominik Stefan This poster presents the current experimental status and prospects for the search of rare four-body charm decays with final states consisting of two oppositely charged kaons or pions and two oppositely charged muons at LHCb. Related links:LHCC Poster Session © CERN Geneva Access to files

2017-03-03
10:04
Search for $\Lambda_{b}^{0}$ and $\Xi_{b}^{0}$ charmless 4-body decays at LHCb
 Reference: Poster-2017-581 Created: 2017. -1 p Creator(s): Vernet, Maxime Quentin The Run I data recorded by the LHCb experiment are analyzed to search for fully charged charmless four-body decays of $b$-flavoured neutral baryons $\Lambda_{b}^{0}$ or $\Xi_{b}^{0}$ . This poster presents the analysis to establish the signals, specially the simultaneous fit model strategy. The proton and antiproton spectra are added in order to allow the determinination of the signal decay branching fractions which are still to be determined. The individual proton and antiproton spectra are kept blinded for the purpose of the forthcoming $\Delta A_{CP}$ measurements of the modes of interest. Related links:LHCC Poster Session © CERN Geneva Access to files

2017-03-03
10:01
Fast simulation options in LHCb from ReDecay to fully parametrised
 Reference: Poster-2017-580 Created: 2017. -1 p Creator(s): Muller, Dominik; Siddi, Benedetto Gianluca With the steady increase in the precision of flavour physics measurements with data from Run 2 of the LHC, the LHCb experiment requires simulated data samples of ever increasing magnitude to study the detector response in detail. However, relying on an increase of computing resources available for the production of simulated samples will not suffice to achieve this goal. Therefore, multiple efforts are currently being investigated to reduce the time needed to simulate an event. This talk presents a summary of those efforts in LHCb, focusing on the newest developments: re-using parts of previously simulated events and a fully parametric detector description using the DELPHES framework. The former merges a simulation of an underlying event multiple times with signal decays simulated separately, achieving an order of magnitude increase in speed with identical precision. The latter provides a parametric solution replacing the full, GEANT4-based simulation, including the smearing of particles' energies, efficiencies and resolutions according to the detector response in a highly-customizable way. Related links:LHCC Poster Session © CERN Geneva Access to files

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