2,685 research outputs found
Impact of the Nuclear Modification of the Gluon Densities on J/Psi production in pPb collisions at sqrt(s_NN) = 5 TeV
We update our previous studies of nuclear-matter effects on J/Psi production
in proton-nucleus for the recent LHC pPb runs at sqrt(s_NN)=5 TeV. We have
analysed the effects of the modification of the gluon PDFs in nucleus, using an
exact kinematics for a 2->2 process, namely g+g->J/Psi+g as expected from LO
pQCD. This allows to constrain the transverse-momentum while computing the
nuclear modification factor for different rapidities, unlike with the usual
simplified kinematics. Owing to the absence of measurement in pp collisions at
the same sqrt(s_NN) and owing to the expected significant uncertainties in
yield interpolations which would hinder definite interpretations of nuclear
modification factor --R_pPb--, we have derived forward-to-backward and
central-to-peripheral yield ratios in which the unknown proton-proton yield
cancel. These have been computed without and with a transverse-momentum cut,
e.g. to comply with the ATLAS and CMS constraints in the central-rapidity
region.Comment: 5 pages, 16 figures, LaTeX. v2: predictions on R_CP and 3 references
added; introduction slightly extende
J/\psi\ and \psi' production in proton(deuteron)-nucleus collisions: lessons from RHIC for the proton-lead LHC run
We study the impact of different cold nuclear matter effects both on J/\psi\
and \psi' production, among them the modification of the gluon distribution in
bound nucleons, commonly known as gluon shadowing, and the survival probability
for a bound state to escape the nucleus --the nuclear absorption. Less
conventional effects such as saturation and fractional energy loss are also
discussed. We pay a particular attention to the recent PHENIX preliminary data
on \psi' production in dAu collisions at sqrt{s}=200 GeV, which show a strong
suppression for central collisions, 5 times larger than the one obtained for
J/\psi\ production at the same energy. We conclude that none of the
abovementioned mechanisms can explain this experimental result.Comment: 4 pages, 2 tables, 2 figures, contribution to Rencontres du Vietnam,
'Heavy Ion Collisions in the LHC Era', 15-21 July 2012, Quy Nhon, Vietna
Open-beauty production in Pb collisions at =5 TeV: effect of the gluon nuclear densities
We present our results on open beauty production in proton-nucleus collisions
for the recent LHC Pb run at =5 TeV. We have analysed the
effect of the modification of the gluon PDFs in nucleus at the level of the
nuclear modification factor. Because of the absence of measurement in
collisions at the same energy, we also propose the study of the
forward-to-backward yield ratio in which the unknown proton-proton yield
cancel. Our results are compared with the data obtained by LHCb collaboration
and show a good agreement.Comment: 6 pages, 3 figures, Proceedings IS2013 submitted to Nuclear Physics
Feasibility studies for quarkonium production at a fixed-target experiment using the LHC proton and lead beams (AFTER@LHC)
Used in the fixed-target mode, the multi-TeV LHC proton and lead beams allow
for studies of heavy-flavour hadroproduction with unprecedented precision at
backward rapidities - far negative Feyman-x - using conventional detection
techniques. At the nominal LHC energies, quarkonia can be studies in detail in
p+p, p+d and p+A collisions at sqrt(s_NN) ~ 115 GeV as well as in Pb+p and Pb+A
collisions at sqrt(s_NN) ~ 72 GeV with luminosities roughly equivalent to that
of the collider mode, i.e. up to 20 fb-1 yr-1 in p+p and p+d collisions, up to
0.6 fb-1 yr-1 in p+A collisions and up to 10 nb-1 yr-1 in Pb+A collisions. In
this paper, we assess the feasibility of such studies by performing fast
simulations using the performance of a LHCb-like detector.Comment: 12 pages, 14 figure
Towards hadronization time determination
We propose a parametrization of the nuclear absorption mechanism relying on
the proper time spent by bound states travelling in nuclear
matter. Our approach could lead to the extraction of charmonium formation time.
It is based on a large amount of proton-nucleus data, from nucleon-nucleon
center-of-mass energies GeV to TeV,
collected in the past 30~years, and for which the main effect on charmonium
production must be its absorption by the nuclear matter it crosses.Comment: 8 pages, 3 figure
Crosstalk Cascades for Frame-rate Pedestrian Detection
Cascades help make sliding window object detection fast,
nevertheless, computational demands remain prohibitive for numerous applications. Currently, evaluation of adjacent windows proceeds independently; this is suboptimal as detector responses at nearby locations and scales are correlated. We propose to exploit these correlations by
tightly coupling detector evaluation of nearby windows. We introduce two opposing mechanisms: detector excitation of promising neighbors and inhibition of inferior neighbors. By enabling neighboring detectors to communicate, crosstalk cascades achieve major gains (4-30x speedup) over cascades evaluated independently at each image location. Combined
with recent advances in fast multi-scale feature computation, for which we provide an optimized implementation, our approach runs at 35-65 fps
on 640 x 480 images while attaining state-of-the-art accuracy
On the theoretical and experimental uncertainties in the extraction of the J/psi absorption cross section in cold nuclear matter
We investigate the cold nuclear matter effects on production, whose
understanding is fundamental to study the quark-gluon plasma. Two of these
effects are of particular relevance: the shadowing of the parton distributions
and the nuclear absorption of the pair. If 's are not
produced {\it via} a process as suggested by recent theoretical
works, one has to modify accordingly the way to compute the nuclear shadowing.
This naturally induces differences in the absorption cross-section fit to the
data. A careful analysis of these differences however requires taking into
account the experimental uncertainties and their correlations, as done in this
work for Au collisions at \sqrtsNN=200\mathrm{GeV}, using several
shadowing parametrisations.Comment: 6 pages, 1 table, 3 figures, Submitted to J. Phys. G, talk given at
the International Conference on Strangeness in Quark Matter (SQM2009),
Buzios, Brasil, Sep. 27 - Oct. 2, 200
Real-time Person Re-identification at the Edge: A Mixed Precision Approach
A critical part of multi-person multi-camera tracking is person
re-identification (re-ID) algorithm, which recognizes and retains identities of
all detected unknown people throughout the video stream. Many re-ID algorithms
today exemplify state of the art results, but not much work has been done to
explore the deployment of such algorithms for computation and power constrained
real-time scenarios. In this paper, we study the effect of using a light-weight
model, MobileNet-v2 for re-ID and investigate the impact of single (FP32)
precision versus half (FP16) precision for training on the server and inference
on the edge nodes. We further compare the results with the baseline model which
uses ResNet-50 on state of the art benchmarks including CUHK03, Market-1501,
and Duke-MTMC. The MobileNet-V2 mixed precision training method can improve
both inference throughput on the edge node, and training time on server
reaching to 27.77fps and , respectively and decreases
power consumption on the edge node by , while it deteriorates
accuracy only 5.6\% in respect to ResNet-50 single precision on the average for
three different datasets. The code and pre-trained networks are publicly
available at https://github.com/TeCSAR-UNCC/person-reid.Comment: This is a pre-print of an article published in International
Conference on Image Analysis and Recognition (ICIAR 2019), Lecture Notes in
Computer Science. The final authenticated version is available online at
https://doi.org/10.1007/978-3-030-27272-2_
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