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2018-05-24
10:43
Search for gluon saturation at Bjorken-x $\in [10^{−6}, 10^{−4}]$ with the LHCb detector(ID:39)
Reference: Poster-2018-629
Keywords:  LHCb
Created: 2018. -1 p
Creator(s): Da Silva, Cesar Luiz

A new state of matter, where gluons have overlapping wave functions, has been in the minds of particle and nuclear physicists for decades. This gluon saturated state could explain several recent observations such as particle production and collectivity observed in p+p, p+A and A+A collisions at RHIC and LHC. The LHCb experiment is a forward spectrometer with vertexing, tracking, $p, K, \pi, e, \mu$ identification and calorimetry in the pseudorapidity region 2< $\eta$ <5. LHCb is therefore well suited to study the gluon density of hadrons in at small Bjorken-x values $(x∼10^{−6}−10^{−5})$, down to two orders of magnitude smaller than HERA. The status of the analysis efforts aimed at finding the gluon saturation scale at LHCb using isolated photon yields and their correlations with hadrons and jets will be shown. In addition, the concept and R&D efforts of a new particle tracker inside the LHCb magnet to improve measurements of small Q2 processes, where gluon saturation is expected, will be presented.

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2018-05-17
14:18
Measurement of the time-integrated CP asymmetry in $D^0 \to K_S^0 K_S^0$ decays with LHCb
Reference: Poster-2018-628
Created: 2018. -1 p
Creator(s): Tuci, Giulia

CP violation in charm has not yet been observed, although measurements of time-integrated CP asymmetries in $D^0 \to K^+K^-$ and $D^0 \to \pi^+\pi^- decays$ have reached a remarkable precision, O(0.1%). The $D^0 \to K_S^0 K_S^0$ decay is a promising discovery channel for CP violation in charm. A prediction based on Standard Model gives an upper limit for the CP asymmetry of 1.1% (C.L. 95%). Further enhancements could result from contributions from physics beyond the Standard Model. We present a measurement of the time-integrated CP asymmetry in prompt $D^0 \to K_S^0 K_S^0$ decays, performed using data collected with LHCb experiment in 2015 and 2016 at a 13 TeV pp center-of-mass energy (Run-2). This result improves the sensitivity obtained by LHCb in Run-1.

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2018-04-24
22:15
Betatron-collimation Studies for Heavy Ions in the FCC-hh
Reference: Poster-2018-627
Note: ORCID: 0000-0002-7669-9837
Keywords:  FCC-hh  Heavy Ions  Collimation  Betatron  STIER  Lossmap
Created: 2018. -1 p
Creator(s): Logothetis Agaliotis, Efstathios; Schaumann, Michaela

One of the biggest challenges in the design of the FCC-hh is the collimation system. From LHC experience it is known that a collimation system optimized for proton cleaning has a significantly reduced efficiency for heavy ions. The study presented in this contribution evaluates the betatron-collimation efficiency for the heavy-ion operation with lead nuclei at a beam energy of 50 Z TeV in the system designed for proton operation. The fragmentation processes of the main beam particles in the primary collimator are simulated with FLUKA and fragments are individually tracked with SixTrack until being lost in the downstream aperture. In this way a first-impact loss-map is obtained, identifying locations where high energy deposition are to be expected. This provides a first-level assessment of feasibility and allows to include countermeasures in the conceptual accelerator design.

Related links:
FCC week 2018
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2018-04-23
15:25
IV Characterisation for the VELO Upgrade
Reference: Poster-2018-626
Created: 2018. -1 p
Creator(s): Franco Lima, Vinicius

LHCb is a dedicated heavy flavour physics experiment that operates at the LHC. The LHCb collaboration plans to change key features of the present detectors for Run III, moving to a full detector readout at 40MHz and operating at a luminosity of 1-2x1033cm-2s-1. The new Vertex Locator (VELO) detector will use hybrid pixel detectors composed of silicon sensors bump-bonded to new VeloPix CMOS readout chips designed for the new 40MHz readout rate. We will present a novel way of delivering bias through the ASIC backside in order to test IV characteristics of sensors in vacuum before module construction. The appropriate laboratory setups developed to test VELO hybrids for production will also be discussed.

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2018-04-05
09:43
A novel standalone track reconstruction algorithm for the LHCb upgrade
Reference: Poster-2018-623
Created: 2018. -1 p
Creator(s): Quagliani, Renato

During the LHC Run III, starting in 2020, the instantaneous luminosity of LHCb will be increased up to 2×1033 cm−2 s−1, five times larger than in Run II. The LHCb detector will then have to be upgraded in 2019. In fact, a full software event reconstruction will be performed at the full bunch crossing rate by the trigger, in order to profit of the higher instantaneous luminosity provided by the accelerator. In addition, all the tracking devices will be replaced and, in particular, a scintillating fiber tracker (SciFi) will be installed after the magnet, allowing to cope with the higher occupancy. The new running conditions, and the tighter timing constraints in the software trigger, represent a big challenge for the track reconstruction. This talk 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 KS and Λ. The implementation strategy is based on a progressive cleaning of the tracking environment and on an active use of the information from the stereo hits in order to select tracks. It also profit from the definition of an improved track parameterization. When compared to its previous implementation, the new algorithm has significantly higher performances in terms of efficiency, number of fake tracks and timing, allowing to enhance the physics potential and capabilities of the LHCb upgrade.

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2018-04-04
15:34
ReDecay, a method to re-use the underlying events to speed up the simulation in LHCb
Reference: Poster-2018-620
Created: 2017. -1 p
Creator(s): Muller, Dominik; Rama, Matteo

With the steady increase in the precision of flavour physics measurements collected during LHC Run 2, the LHCb experiment requires simulated data samples of ever increasing magnitude to study the detector response in detail. However, relying on an increase of available computing power for the production of simulated events will not suffice to achieve this goal. The simulation of the detector response is the main contribution to the time needed to generate a sample, that scales linearly with the particles multiplicity of the event. Of the dozens of particles present in the simulation only a few, namely those participating in the studied signal decay, are of particular interest, while all remaining ones, the so-called underlying event, mainly affect the resolution and efficiencies of the detector. This talk presents a novel development for the LHCb simulation software which re-uses the underlying event from previously simulated events. This approach achieves an order of magnitude increase in speed and the same precision compared to the nominal simulation.

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2018-03-29
16:12
Сharmonium production using decays to hadronic final states at LHCb
Reference: Poster-2018-619
Created: 2018. -1 p
Creator(s): Usachov, Andrii

Non Relativistic QCD (NRQCD) provides so far the most successful framework to describe the production of the $J^{PC}=1^{--}$ quarkonium states. However, a comprehensive description of the production and polarisation of the $J/\psi$ state at Tevatron and LHC in the complete $p_T$ and rapidity range remains a challenge. The heavy quark spin symmetry yields direct links between the long distance matrix elements describing hadroproduction of different charmonium states. The production of linked charmonium states - $\eta_c$ and $J/\psi$, $\eta_c(2S)$ and $\psi(2S)$, and the three $\chi_c$ states - can thus be described simultaneously. Experimentally the production of non-$1^{--}$ charmonium states can be studied by reconstructing their decays to fully hadronic final states. The LHCb measurement of the $\eta_c(1S)$ prompt production and production in inclusive b-hadron decays via the decay $\eta_c(1S)\to p\bar{p}$ is discussed together with its strong impact on NRQCD-based theory models. Recent LHCb measurement of the $\chi_c$ and $\eta_c(2S)$ states production in inclusive b-hadron decays using their decays to $\phi\phi$ is also presented; the discrepancy with existing theoretical prediction is demonstrated. Prospects of measuring prompt $\eta_c(2S)$ production at the LHCb using 2018 data is discussed.

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2018-03-14
10:41
Il Bosone di Higgs

Reference: Poster-2018-617
Keywords:  ATLAS  Higgs  Poster  Divulgazione  BEM  Meccanismo di Higgs  Meccanismo BEH  A0
Created: 2018. -1 p
Creator(s): Hemmer, Sabine

Poster di ATLAS sul bosone di Higgs indirizzato al pubblico generico, che spiega il meccanismo di Brout-Englert-Higgs e la sua importanza. Spiega anche il ruolo del Bosone di Higgs, come viene cercato, il percorso della sua scoperta e cosa viene dopo la scoperta. Disponibile anche in Francese (http://cds.cern.ch/record/1697501) e Inglese (http://cds.cern.ch/record/1697389). Non esitate a utilizzarlo nelle sedi dei vostri Istituti e negli eventi divulgativi! Il poster è in formato A0. Cliccate sull'immagine per scaricare il .pdf ad alta qualità e stamparlo dove preferite. Per qualisasi domanda o commento potete contattare atlas-outreach-coordination@cern.ch

Related links:
English Version
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2018-03-06
14:44
Time-dependent CP violation in $B^0_{(s)} \to h^+h^-$ decays
Reference: Poster-2018-616
Created: 2018. -1 p
Creator(s): Fazzini, Davide

The direct and mixing-induced CP-violating asymmetries in $B^0 \to \pi^+ \pi^-$ and $B_s \to K^+ K^-$ decays have been measured using a sample of pp collisions collected by the LHCb experiment during the Run1 of the LHC and corresponding to an integrated luminosity of 3.0 fb$^{-1}$.The time-integrated CP asymmetries in $B^0 \to K^+ \pi^-$ and $B_s \to \pi^+ K^-$ decays have also been measured, using the same data sample.The measurements of the CP-violating asymmetries of the $B^0 \to \pi^+ \pi^-$, $B_s \to K^+\pi^-$ and $B_s \to \pi^+K^-$ decays are the most precise from a single experiment. The measurements of the CP-violating asymmetries of the Bs->KK decays are compatible with the previous results from LHCb.

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2018-03-06
14:25
Observation of the decay $B \to p\overline{p}\mu\nu$ and Lepton Flavour Universality with $B \to p\overline{p}\mu\nu$
Reference: Poster-2018-615
Created: 2018. -1 p
Creator(s): Tilley, Matthew James

The first observation of the $B \to p\overline{p}\mu$ decay should be possible at the LHCb experiment with a significance far in excess of 5$\sigma$ . As well as a branching fraction measurement, a precision measurement of the $p\overline{p}$ mass spectrum will be performed. The ratio of branching fractions $\mathcal{B}(B \to p\overline{p}\tau)/\mathcal{B}(B \to p\overline{p}\mu)$ is a test of lepton flavour universality in the Standard Model. This measurement is in progress at LHCb and would be the first test involving a $b\to u\tau\nu$ transition.

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Open Days 2013 Posters (58)