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# Posters

2013-05-30
09:30
Search for Neutral MSSM Higgs bosons decaying to tau pairs in the ATLAS experiment
 Reference: Poster-2013-268 Created: 2013. -1 p Creator(s): Scutti, F The Minimal Supersymmetric Standard Model (MSSM) is a supersymmetric extension of the Standard Model of particle physics, predicting the existence of five Higgs bosons, two charged (H±) and three neutral (h, H, A). At tree level their properties are determined by two independent parameters: the mass of the CP-odd Higgs boson mA, and the ratio between the vacuum expectation values of the two Higgs doublets predicted tan(beta). In Supersymmetric models, the Higgs boson couplings to down-type fermions like b-quarks or tau leptons is significantly enhanced over a large region of the parameter space. Decays to tau lepton pairs occur 10% of the times and provide a cleaner environment for the search than decays to b-quarks. The tau lepton can decay into either a muon or an electron, plus neutrinos, or in hadrons plus neutrinos. In this poster, the search for the heavy neutral MSSM Higgses (h, H, A) is presented, where the final state is a pair of hadronically decaying tau leptons. This channel provides good sensitivity to discovery in the hypothesis of high mass signal. Signal events have to be separated from the background which is dominated by di-jet events from strong interaction processes, Drell-Yan events and W+jets. The event selection is optimized in two independent categories providing their best sensitivities in different mass regions. © CERN Geneva Access to file

2013-05-27
10:37
LHCb; Measurement of the forward-central $b \bar{b}$ production asymmetry
 Reference: Poster-2013-267 Keywords:  LHCb  flavour physics Created: 2013. -1 p Creator(s): Salustino Guimarães, V CDF and D0 collaborations results suggests that the top-quark forward-backward production asymmetry is much larger than the Standard Model (SM) predictions. Measuring the $b \bar{b}$ asymmetry production would provide constraint on the flavor structure of any model that attempts to explain the CDF and D0 results. A measurement of the forward-central (FC) $b\bar{b}$ production asymmetry is presented based on the LHCb data collected in 2011 at $\sqrt{s}$ = 7 TeV corresponding to an integrated luminosity of 1.0 fb$^{-1}$ using selected events that have two identified $b$ jets, one of which is flavor tagged by one muon with high momentum. The FC asymmetry is defined as \begin{align} A^{b \bar{b}}_{FC}=\frac{N(\Delta y > 0)-N(\Delta y < 0)}{N(\Delta y > 0)+N(\Delta y < 0)} \end{align} where $\Delta y = \mid y_b \mid - \mid y_{\bar{b} \mid}$ is the rapidity difference between $b$ and $\bar{b}$ No SM precise prediction is evaluated but there is a consensus that at Low $M_{b \bar{b}}$ gluon fusion dominates resulting in $\cal{O}$(0.1 %) asymmetry. For $M_{b \bar{b}} > 100$ GeV the expected asymmetry is about $\cal{O}$(0.1 %) where gluon fusion which has no asymmetry is less dominant at high mass. Related links:Conference: Flavor Physics & CP Violation 2013 © CERN Geneva Access to file

2013-05-24
08:30
LHCb: Evidence of CP violation in charmless three-body decays $B^\pm\rightarrow K^\pm\pi^+\pi^-$, $B^\pm\rightarrow K^\pm K^+K^-$, $B^\pm\rightarrow K^+ K^-\pi^\pm$ and $B^\pm\rightarrow \pi^\pm\pi^+\pi^-$
 Reference: Poster-2013-266 Keywords:  flavour physics  CP violation Created: 2013. -1 p Creator(s): Lopes, J H Evidence of CP violation in charmless three-body decays $B^\pm\rightarrow K^\pm\pi^+\pi^-$, $B^\pm\rightarrow K^\pm K^+K^-$, $B^\pm\rightarrow K^+ K^-\pi^\pm$ and $B^\pm\rightarrow \pi^\pm\pi^+\pi^-$ Related links:Conference: Flavor Physics & CP Violation 2013 © CERN Geneva Access to file

2013-04-16
13:28
 Reference: Poster-2013-265 Keywords:  flavour physics Created: 2013. -1 p Creator(s): Orlandea, M In this work we present a measurement of the ratio of the branching fraction of the radiative decays $B^{0}\rightarrow K^{*0}\gamma$ and $B^{0}_{s}\rightarrow \phi\gamma$ using 1.0 fb$^{-1}$ of data taken with the LHCb detector. The value obtained is $$\frac{B\left(B^{0}\rightarrow K^{*0}\gamma\right)}{B\left(B^{0}_{s}\rightarrow \phi\gamma\right)}=1.23\pm0.06(stat.)\pm0.04(syst.)\pm0.10\left(f_s/f_d\right)$$ Using the world average value $B\left(B^{0}\rightarrow K^{*0}\gamma\right)=\left(4.33\pm0.15\right)\times10^{-5}$ branching fraction is determined to be $B\left(B^{0}_{s}\rightarrow \phi\gamma\right)=3.5\pm0.4\times10^{-5}$. A measurement of the direct CP asymmetry of the decay $B^{0}\rightarrow K^{*0}\gamma$ is also presented. Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations. Related links:Conference: Beauty 2013 - The 14th International Conference on B-Physics at Hadron Machines © CERN Geneva Access to files

2013-04-12
12:19
LHCb: Optimization and Calibration of Flavour Tagging Algorithms for the LHCb experiment
 Reference: Poster-2013-264 Keywords:  detector Created: 2013. -1 p Creator(s): Falabella, A The LHCb purposes are to make precise measurements of $B$ and $D$ meson decays. In particular in time-dependent CP violation studies the determination of $B$ flavour at production is fundamental. This is known as "flavour tagging" and at LHCb it is performed with several algorithms. The performances and calibration of the flavour tagging algorithms with 2011 data collected by LHCb are reported. Also the performances of the flavour tagging algorithms in the relevant CP violation and asymmetry studies are also reported. Related links:Conference: Beauty 2013 - The 14th International Conference on B-Physics at Hadron Machines © CERN Geneva Access to files

2013-04-11
13:57
LHCb: LHCb Muon System Performance at High Luminosity
 Reference: Poster-2013-263 Keywords:  LHCb  muon Created: 2013. -1 p Creator(s): Pinci, D The LHCb detector was conceived to operate with an average Luminosity of $2 \times 10^{32}$ cm$^{-2}$ s$^{-1}$. During the last year of LHC run, the whole apparatus has shown to be able to perfectly acquire and manage data produced at a Luminosity as high as $4 \times 10^{32}$ cm$^{-2}$ s$^{-1}$. In these conditions, all sub-detectors operated at average particle rates higher than the design ones and in particular the Multi-Wire Proportional Chambers equipping the Muon System had to sustain a particle rate as high as 250 kHz/cm$^{2}$. In order to study the possibility of increasing the Luminosity of operation of the whole experiment several tests were performed. The effective beam Luminosity at the interaction point of LHCb was increased in several steps up to $10^{33}$ cm$^{-2}$ s$^{-1}$ and in each step the behavior of all the detectors in the Muon System was recorded. The data analysis has allowed to study the performance of the Muon System as a function of the LHC Luminosity and the results are reported in this presentation. Related links:Conference: Beauty 2013 - The 14th International Conference on B-Physics at Hadron Machines © CERN Geneva Access to file

2013-03-18
16:34
LHCb: Charmless $B \to 3$ body decays at LHCb
 Reference: Poster-2013-262 Keywords:  flavour physics Created: 2013. -1 p Creator(s): Prisciandaro, J Charmless $B \to 3$ body decays at LHCb Related links:Conference: LHC students poster session © CERN Geneva Access to file

2013-03-18
16:30
LHCb: Search for CP violation in four-body charm decays
 Reference: Poster-2013-261 Keywords:  flavour physics  CP violation Created: 2013. -1 p Creator(s): Coombes, M Use a model independent binned method to search for CP violation in singly Cabibbo suppressed four body charm decays. CP violation $\succ \mathcal {O}(10^{-3})$ would point toward new physics. Related links:Conference: LHC students poster session © CERN Geneva Access to file

2013-03-18
16:23
LHCb; Neutral Higgs $\to \tau \tau$ Limits at LHCb
 Reference: Poster-2013-260 Keywords:  Higgs physics Created: 2013. -1 p Creator(s): Ilten, P LHCb is fully instrumented in the forward region, $2 \leq \eta \leq 5$, and provides compelentary results to the central measurements of ATLAS and CMS. Preliminary limits are presented on neutral Higgs production usint $\tau \tau$ final states in the forward region of LHCb. Related links:Conference: LHC students poster session © CERN Geneva Access to file

2013-03-18
16:03
LHCb: Search for $D^{+}_{(s)} \rightarrow \pi^+ \mu^+ \mu^-$ and $D^{+}_{(s)} \rightarrow \pi^- \mu^+ \mu^+$ decays
 Reference: Poster-2013-259 Keywords:  flavour physics  rare decay Created: 2013. -1 p Creator(s): Greening, E A search for non-resonant $D^{+}_{(s)} \rightarrow \pi^+ \mu^+ \mu^-$ and $D^{+}_{(s)} \rightarrow \pi^- \mu^+ \mu^+$ decays is performed using 1.0 $fb^{-1}$ of proton-proton collisions at s = 7 TeV recorded by the LHCb experiment. No signals are observed and the world's best limits on the branching fractions are set. Related links:Conference: LHC students poster session © CERN Geneva Access to files