512 research outputs found
Unitarity Triangle Fitter Results for CKM Angles
We present the status of the Unitarity Triangle analysis focused on the
analyses connected to the CKM angles extraction. The angle values are found to
be , , and
.Comment: Proceedings of CKM 2012, the 7th International Workshop on the CKM
Unitarity Triangle, University of Cincinnati, USA, 28 September - 2 October
201
Inclusive Flavour Tagging Algorithm
Identifying the flavour of neutral mesons production is one of the most
important components needed in the study of time-dependent violation. The
harsh environment of the Large Hadron Collider makes it particularly hard to
succeed in this task. We present an inclusive flavour-tagging algorithm as an
upgrade of the algorithms currently used by the LHCb experiment. Specifically,
a probabilistic model which efficiently combines information from reconstructed
vertices and tracks using machine learning is proposed. The algorithm does not
use information about underlying physics process. It reduces the dependence on
the performance of lower level identification capacities and thus increases the
overall performance. The proposed inclusive flavour-tagging algorithm is
applicable to tag the flavour of mesons in any proton-proton experiment.Comment: 5 pages, 5 figures, 17th International workshop on Advanced Computing
and Analysis Techniques in physics research (ACAT-2016
Numerical optimization for Artificial Retina Algorithm
High-energy physics experiments rely on reconstruction of the trajectories of
particles produced at the interaction point. This is a challenging task,
especially in the high track multiplicity environment generated by p-p
collisions at the LHC energies. A typical event includes hundreds of signal
examples (interesting decays) and a significant amount of noise (uninteresting
examples).
This work describes a modification of the Artificial Retina algorithm for
fast track finding: numerical optimization methods were adopted for fast local
track search. This approach allows for considerable reduction of the total
computational time per event. Test results on simplified simulated model of
LHCb VELO (VErtex LOcator) detector are presented. Also this approach is
well-suited for implementation of paralleled computations as GPGPU which look
very attractive in the context of upcoming detector upgrades
Cherenkov Detectors Fast Simulation Using Neural Networks
We propose a way to simulate Cherenkov detector response using a generative
adversarial neural network to bypass low-level details. This network is trained
to reproduce high level features of the simulated detector events based on
input observables of incident particles. This allows the dramatic increase of
simulation speed. We demonstrate that this approach provides simulation
precision which is consistent with the baseline and discuss possible
implications of these results.Comment: In proceedings of 10th International Workshop on Ring Imaging
Cherenkov Detector
Multi-pomeron exchange model for and collisions at ultra-high energy
A new variant of the effective pomeron exchange model is proposed for the
description of the correlation, observed in and collisions at
center-of-mass energy from SPS to LHC, between mean transverse momentum and
charged particles multiplicity. The model is based on the Regge-Gribov
approach. Smooth logarithmic growth with the collision energy was established
for the parameter k, the mean rapidity density of charged particles produced by
a single string. It was obtained in the model by the fitting of the available
experimental data on charged particles rapidity density in and
collisions. The main effect of the model, a gradual onset of string
collectivity with the growth of collision energy, is accounted by a free
parameter {\beta} that is responsible in an effective way for the string fusion
phenomenon. Another free parameter, t, is used to define string tension. We
extract parameters {\beta} and t from the available experimental results on
-multiplicity correlation at nucleon collision energy from 17
GeV to 7 TeV. Smooth dependence of both {\beta} and t on energy allows to make
predictions for the correlation behavior at the collision energy of 14 TeV. The
indications to the string interaction effects in high multiplicity events in
collisions at the LHC energies are also discussed.Comment: 7 pages, 7 figures, to appear in proc. QFTHEP'201
Fast Data-Driven Simulation of Cherenkov Detectors Using Generative Adversarial Networks
The increasing luminosities of future Large Hadron Collider runs and next
generation of collider experiments will require an unprecedented amount of
simulated events to be produced. Such large scale productions are extremely
demanding in terms of computing resources. Thus new approaches to event
generation and simulation of detector responses are needed. In LHCb, the
accurate simulation of Cherenkov detectors takes a sizeable fraction of CPU
time. An alternative approach is described here, when one generates high-level
reconstructed observables using a generative neural network to bypass low level
details. This network is trained to reproduce the particle species likelihood
function values based on the track kinematic parameters and detector occupancy.
The fast simulation is trained using real data samples collected by LHCb during
run 2. We demonstrate that this approach provides high-fidelity results.Comment: Proceedings for 19th International Workshop on Advanced Computing and
Analysis Techniques in Physics Research. (Fixed typos and added one missing
reference in the revised version.
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