2,624 research outputs found
Determination of QCD Backgrounds in ATLAS: A challenge for SUSY searches
In this paper we briefly discuss the estimation of uncertainties in QCD
backgrounds to searches for Supersymmetry under development by the ATLAS
collaboration.Comment: Proceedings of SUY09. Boston (USA
Fake Missing Transverse Energy from Calorimeter Effects
In this paper we discuss briefly the correlation between fake missing
transverse energy and jets pointing to crack regions in the ATLAS calorimeters.Comment: Prepared for the BSM-LHC Whitepaper (Nuclear Physics B
Searching for doubly-charged vector bileptons in the Golden Channel at the LHC
In this paper we investigate the LHC potential for discovering doubly-charged
vector bileptons considering the measurable process
. We perform the study using four different
bilepton masses and three different exotics quark masses. Minimal LHC
integrated luminosities needed for discovering and for setting limits on
bilepton masses are obtained for both 7 TeV and 14 TeV center-of-mass energies.
We find that these spectacular signatures can be observed at the LHC in the
next years up to a bilepton mass of order of 1 TeV.Comment: 8 pages, 10 figure
Virtual bilepton effects in polarized Moller scattering
We investigate the indirect effects of heavy vector bileptons being exchanged
in polarized Moller scattering, at the next generation of linear colliders.
Considering both longitudinal and transverse beam polarization, and accounting
for initial-state radiation, beamstrahlung and beam energy spread, we discuss
how angular distributions and asymmetries can be used to detect clear signals
of virtual bileptons, and the possibility of distinguishing theoretical models
that incorporate these exotic particles. We then estimate 95% C.L. bounds on
the mass of these vector bileptons and on their couplings to electrons.Comment: 19 pages, 10 figure
Time of Flight Analysis Using Cosmic Ray Muons in the ATLAS Tile Calorimeter
Using cosmic ray muon data recorded during the summer of 2007, we have studied the time-of-flight distributions between back-to-back modules of the ATLAS Tile Calorimeter. The results are in good agreement with the distributions expected from calorimeter geometry, and allow for cross-checks of timing corrections obtained in laser runs. Calorimeter timing is a useful tool to remove non-physics backgrounds, and we introduce new cuts at the cell level which improve the signal-to-noise ratio
The HIBEAM/NNBAR Calorimeter Prototype
The HIBEAM/NNBAR experiment is a free-neutron search for
sterile and oscillations planned to be installed at
the European Spallation Source under construction in Lund, Sweden. A key
component in the experiment is the detector to identify
annihilation events, which will produce on average four pions with a final
state invariant mass of two nucleons, around GeV. The beamline and
experiment are shielded from magnetic fields which would suppress transitions, thus no momentum measurement will be
possible. Additionally, calorimetry for particles with kinetic energies below
MeV is challenging, as traditional sampling calorimeters used in HEP
would suffer from poor shower statistics. A design study is underway to use a
novel approach of a hadronic range measurement in multiple plastic scintillator
layers, followed by EM calorimetery with lead glass. A prototype calorimeter
system is being built, and will eventually be installed at an ESS test beam
line for \textit{in situ} neutron background studies.Comment: Contribution to the International Conference on Technology and
Instrumentation in Particle Physics (TIPP2021
Explaining the Higgs Decays at the LHC with an Extended Electroweak Model
We show that the recent discovery of a new boson at the LHC, which we assume
to be a Higgs boson, and the observed enhancement in its diphoton decays
compared to the SM prediction, can be explained by a new doublet of charged
vector bosons from an extended electroweak gauge sector model with
SU(3)_C\otimesSU(3)_L\otimesU(1)_X symmetry. Our results show a good
agreement between our theoretical expected sensitivity to a 126--125 GeV Higgs
boson and the experimental significance observed in the diphoton channel at the
8 TeV LHC. Effects of an invisible decay channel for the Higgs boson are also
taken into account, in order to anticipate a possible confirmation of deficits
in the branching ratios into , , bottom quarks, and tau leptons.Comment: 16 pages, 5 figure
Searching for vector bileptons in polarized Bhabha scattering
In this paper we analyze the effects of virtual vector bileptons in polarized
Bhabha scattering at the energies of the future linear colliders. In order to
make the calculations of the differential cross sections more realistic,
important beam effects such as initial state radiation, beamstrahlung, beam
energy and polarization spreads are accounted for. The finite resolution of a
typical electromagnetic calorimeter planned for the new linear colliders is
also considered in the simulation. The 95% confidence level limits for bilepton
masses in 331 models are evaluated.Comment: Accepted for publication in the Journal of Physics G: Nuclear and
Particle Physic
Hunt for new phenomena using large jet multiplicities and missing transverse momentum with ATLAS in 4.7 fb−1 of s√=7TeV proton-proton collisions
Results are presented of a search for new particles decaying to large numbers of jets in association with missing transverse momentum, using 4.7 fb−1 of pp collision data at s√=7TeV collected by the ATLAS experiment at the Large Hadron Collider in 2011. The event selection requires missing transverse momentum, no isolated electrons or muons, and from ≥6 to ≥9 jets. No evidence is found for physics beyond the Standard Model. The results are interpreted in the context of a MSUGRA/CMSSM supersymmetric model, where, for large universal scalar mass m 0, gluino masses smaller than 840 GeV are excluded at the 95% confidence level, extending previously published limits. Within a simplified model containing only a gluino octet and a neutralino, gluino masses smaller than 870 GeV are similarly excluded for neutralino masses below 100 GeV