3,467 research outputs found
The CMS muon system in Run2: preparation, status and first results
The CMS muon system has played a key role for many physics results obtained
from the LHC Run-1 data. During the Long Shutdown (2013-2014) significant
upgrades have been carried out on the muon detectors and on the L1 muon
trigger. In parallel the algorithms for muon reconstruction and identification
have been improved for both the High-Level Trigger and the offline
reconstruction. Results of studies performed on data and Monte Carlo
simulations will be presented, with focus on the improvements aiming to ensure
an excellent performance in conditions of multiplicity of pileup events and
bunch spacing expected during the high-luminosity phase of Run-2. The early
muon performance results from LHC Run-2 will be shown.Comment: 8 pages, 13 figures, to be published in the proceedings of EPS-HEP
201
Status of the MUonE experiment
The MUonE experiment has been proposed to measure the differential cross
section of elastic scattering, by colliding the 160 GeV muons of the
CERN M2 beam with atomic electrons of thin target plates. From a very precise
measurement of the shape one can achieve a competitive determination of the
leading hadronic contribution to the muon magnetic moment, independent from the
other existing ones. In preparation for the Test Run with a reduced setup the
detector geometry has been optimised. Expected yields for a first physics run
with limited statistics are discussed, together with prospects for the
assessment of the main systematic uncertainties.Comment: 18 pages, 11 figures, contributed to the 10th International
Conference on New Frontiers in Physics (ICNFP 2021), 23 August-7 October
2021, Crete, Greec
Signatures of massive sgoldstinos at hadron colliders
In supersymmetric extensions of the Standard Model with a very light
gravitino, the effective theory at the weak scale should contain not only the
goldstino, but also its supersymmetric partners, the sgoldstinos. In the
simplest case, the goldstino is a gauge-singlet and its superpartners are two
neutral spin-0 particles, S and P. We study possible signals of massive
sgoldstinos at hadron colliders, focusing on those that are most relevant for
the Tevatron. We show that inclusive production of sgoldstinos, followed by
their decay into two photons, can lead to observable signals or to stringent
combined bounds on the gravitino and sgoldstino masses. Sgoldstino decays into
two gluon jets may provide a useful complementary signature.Comment: 20 pages, 6 figures. Corrected misprint, added reference
Signatures of massive sgoldstinos at e+e- colliders
In supersymmetric extensions of the Standard Model with a very light
gravitino, the effective theory at the weak scale should contain not only the
goldstino G, but also its supersymmetric partners, the sgoldstinos. In the
simplest case, the goldstino is a gauge-singlet and its superpartners are two
neutral spin-0 particles, S and P. We study possible signals of massive
sgoldstinos at e+e- colliders, focusing on those that are most relevant at LEP
energies. We show that the LEP constraints on e+e- => photon+S (photon+P), Z+S
(Z+P) or e+e-S (e+e-P), followed by S (P) decaying into two gluon jets, can
lead to stringent combined bounds on the gravitino and sgoldstino masses.Comment: 22 pages, 8 figures. Published version with note adde
Theoretical predictions for charm and bottom production at the LHC
We present predictions for a variety of single-inclusive observables that
stem from the production of charm and bottom quark pairs at the 7 TeV LHC. They
are obtained within the FONLL semi-analytical framework, and with two "Monte
Carlo + NLO" approaches, MC@NLO and POWHEG. Results are given for final states
and acceptance cuts that are as close as possible to those used by experimental
collaborations and, where feasible, are compared to LHC data.Comment: 22 pages, 10 figure
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO