224,253 research outputs found
Sector logic implementation for the ATLAS endcap level-1 muon trigger
We present development of the Sector Logic for the ATLAS endcap Level-1 (LVL1) muon trigger. The muon tracks from the interaction point (IP) are bent by the magnetic fields induced by the ATLAS toroidal magnets. The Sector Logic reconstructs three dimensional muon tracks with six levels of transverse momentum (pT) by combining two sets (R-Z and φ-Z) of information from the Thin Gap Chamber (TGC) detectors. Then, it selects two highest pT tracks in each trigger sector. The Sector Logic module is designed in pipelined structure to achieve no-dead-time operation and shorter latency. Look-Up-Tables (LUTs) are used so that any pT threshold level can be set. To achieve these, we adopted SRAM embedded type FPGA devices. The design and its performance are given in this presentation
Closing in on compressed gluino-neutralino spectra at the LHC
A huge swath of parameter space in the context of the Minimal Supersymmetric
Standard Model (MSSM) has been ruled at after run I of the LHC. Various
exclusion contours in the m_{\tilde{g}}-\m_{\tilde{\chi}_{1}^{0}} plane were
derived by the experimental collaborations, all based on three-body gluino
decay topologies. These limits are however extremely model dependent and do not
always reflect the level of exclusion. If the gluino-neutralino spectrum is
compressed, then the current mass limits can be drastically reduced. In such
situations, the radiative decay of the gluino \gino \ra g \neut{1} can be
dominant and used as a sensitive probe of small mass splittings. We examine the
sensitivity of constraints of some Run I experimental searches on this decay
after recasting them within the \texttt{MadAnalysis5} framework. The recasted
searches are now part of the \texttt{MadAnalysis5} Public Analysis Database. We
also design a dedicated search strategy and investigate its prospects to
uncover this decay mode of the gluino at run II of the LHC. We emphasize that a
multijet search strategy may be more sensitive than a monojet one, even in the
case of very small mass differences.Comment: 34 pages , 6 figures. Version accepted for publication for JHE
Revisiting LHC gluino mass bounds through radiative decays using MadAnalysis 5
The ATLAS and CMS experiments at the CERN LHC have collected about 25 inverse
femtobarns (fb) of data each at the end of their 8 TeV run, and ruled out a
huge swath of parameter space in the context of Minimally Supersymmetric
Standard Model (MSSM). Limits on masses of the gluino have been pushed to above
1 TeV. These limits are however extremely model dependent and do not always
reflect the level of exclusion. So far the limits on the gluino mass using the
simplified model approach only constrained its value using its three-body
decays. We show in this work that already existing ATLAS and CMS analysis can
also constrain the radiative gluino decay mode and we derived improved mass
limits in particular when the mass difference between the LSP and the gluino is
small.Comment: 4 pages, 3 figures. To appear in the proceedings of the 27th
Rencontres the Blois on Particle Physics and Cosmology, May 31 - June 05,
201
Probing the NMSSM via Higgs boson signatures from stop cascade decays at the LHC
Higgs signatures from the cascade decays of light stops are an interesting
possibility in the next to minimal supersymmetric standard model (NMSSM). We
investigate the potential reach of the light stop mass at the 13 TeV run of the
LHC by means of five NMSSM benchmark points where this signature is dominant.
These benchmark points are compatible with current Higgs coupling measurements,
LHC constraints, dark matter relic density and direct detection constraints. We
consider single and di-lepton search strategies, as well as the
jet-substructure technique to reconstruct the Higgs bosons. We find that one
can probe stop masses up to 1.2 TeV with 300 luminosity via the
di-lepton channel, while with the jet-substructure method, stop masses up to 1
TeV can be probed with 300 luminosity. We also investigate the
possibility of the appearance of multiple Higgs peaks over the background in
the fat-jet mass distribution, and conclude that such a possibility is viable
only at the high luminosity run of 13 TeV LHC.Comment: 20 pages, 5 figures; Two figures updated, typos corrected. Matched
with the published versio
On the intrinsic bottom content of the nucleon and its impact on heavy new physics at the LHC
Heavy quark parton distribution functions (PDFs) play an important role in
several Standard Model and New Physics processes. Most analyses rely on the
assumption that the charm and bottom PDFs are generated perturbatively by gluon
splitting and do not involve any non-perturbative degrees of freedom. It is
clearly necessary to test this hypothesis with suitable QCD processes.
Conversely, a non-perturbative, intrinsic heavy quark parton distribution has
been predicted in the literature. We demonstrate that to a very good
approximation the scale-evolution of the intrinsic heavy quark content of the
nucleon is governed by non-singlet evolution equations. This allows us to
analyze the intrinsic heavy quark distributions without having to resort to a
full-fledged global analysis of parton distribution functions. We exploit this
freedom to model intrinsic bottom distributions which are so far missing in the
literature in order to estimate the impact of this non-perturbative
contribution to the bottom-quark PDF, and on parton--parton luminosities at the
LHC. This technique can be applied to the case of intrinsic charm, albeit
within the limitations outlined in the following.Comment: 23 pages, 11 figure
GASTOF: Ultra-fast ToF forward detector for exclusive processes at the LHC
GASTOF (Gas Time-of-Flight) detector is a Cherenkov detector proposed for
very precise (10--20 ps) arrival time measurements of forward protons at some
420 m from the central detectors of CMS and ATLAS. Such an excellent time
resolution will allow by z-by-timing technique for precise measurement of the
z-coordinate of the event vertex in exclusive production at the LHC, when two
colliding protons are scattered at very small angles. In the paper we present
first GASTOF prototype, simulations of its performance as well as first tests
using a cosmic muon telescope.Comment: 6 pages, 3 figures, presented at the conference ''Physics at LHC'',
Krakow, June 200
Reinterpretation of LHC Results for New Physics: Status and recommendations after Run 2
We report on the status of efforts to improve the reinterpretation of searches and measurements at the LHC in terms of models for new physics, in the context of the LHC Reinterpretation Forum. We detail current experimental offerings in direct searches for new particles, measurements, technical implementations and Open Data, and provide a set of recommendations for further improving the presentation of LHC results in order to better enable reinterpretation in the future. We also provide a brief description of existing software reinterpretation frameworks and recent global analyses of new physics that make use of the current data
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