The new numerical approach that includes
1
⊗
2
mechanisms is applied to double parton scattering (DPS) in W+dijet and Z+dijet final-state production in proton–proton collisions at the LHC. By using ...the underlying event (UE) simulation from a
pythia
8.205 tune extracted in hadronic events, we show that, like in the case of a four-jet final state, the inclusion of
1
⊗
2
mechanisms improves the description of experimental data measured at 7 TeV. The analysis is based on applying an event-by-event reweighting factor to a standard
pythia
8.205 sample, by using the theoretical value of
σ
eff
, which includes corrections due to
1
⊗
2
mechanisms. In addition, predictions for proton–proton collisions at a center-of-mass energy of 13 TeV are shown for DPS-sensitive observables. The relevant code, used for this analysis, is publicly available at the following link:
http://desy.de/~gunnep/SigmaEffectiveDependence/
.
We modify the treatment of multiple parton interactions (MPI) in
Pythia
by including the
1
⊗
2
mechanism and treating the
2
⊗
2
mechanism in a model-independent way. The
2
⊗
2
mechanism is calculated ...within the mean field approximation, and its parameters are expressed through generalized parton distributions extracted from HERA data. The parameters related to the transverse parton distribution inside the proton are thus independent of the performed fit. The
1
⊗
2
mechanism is included along the lines of the recently developed formalism in perturbative QCD. A unified description of MPI at moderate and hard transverse momenta is obtained within a consistent framework, in good agreement with experimental data measured at 7 TeV. Predictions are also shown for the considered observables at 14 TeV. The corresponding code implementing the new MPI approach is made available.
By using predictions from the
Pythia
8 Monte Carlo event generator, we determine the energy-dependent turn-over values (
p
T0
) of the partonic cross section for the simulation of multiparton ...interactions. Since the observed energy dependence of the
p
T0
values is not well described by a power-law function, we introduce an additional energy-dependent term, to better describe the experimental observations in the energy range
s
=
0.3
-
13
TeV
. We obtain a similar level of agreement for predictions using various parton densities.
By using predictions from the Pythia 8 Monte Carlo event generator, we determine the energy-dependent turn-over values ( Formula omitted) of the partonic cross section for the simulation of ...multiparton interactions. Since the observed energy dependence of the Formula omitted values is not well described by a power-law function, we introduce an additional energy-dependent term, to better describe the experimental observations in the energy range Formula omitted. We obtain a similar level of agreement for predictions using various parton densities.
By using predictions from the Pythia 8 Monte Carlo event generator, we determine the energy-dependent turn-over values (pT0) of the partonic cross section for the simulation of multiparton ...interactions. Since the observed energy dependence of the pT0 values is not well described by a power-law function, we introduce an additional energy-dependent term, to better describe the experimental observations in the energy range s=0.3-13TeV. We obtain a similar level of agreement for predictions using various parton densities.
Abstract By using predictions from the Pythia 8 Monte Carlo event generator, we determine the energy-dependent turn-over values ($$p_{\text {T0}}$$ pT0 ) of the partonic cross section for the ...simulation of multiparton interactions. Since the observed energy dependence of the $$p_{\text {T0}}$$ pT0 values is not well described by a power-law function, we introduce an additional energy-dependent term, to better describe the experimental observations in the energy range $$\sqrt{s} = 0.3-13 \, \hbox {TeV}$$ s=0.3-13TeV . We obtain a similar level of agreement for predictions using various parton densities.
Pixelated silicon detectors are state-of-the-art technology to achieve precise tracking and vertexing at collider experiments, designed to accurately measure the hit position of incoming particles in ...high rate and radiation environments. The detector requirements become extremely demanding for operation at the High-Luminosity LHC, where up to 200 interactions will overlap in the same bunch crossing on top of the process of interest. Additionally, fluences up to 2.3 × 1016cm−2 1MeV neutron equivalent at 3.0cm distance from the beam are expected for an integrated luminosity of 3000fb−1. In the last decades, the pixel pitch has constantly been reduced to cope with the experiments’ needs of achieving higher position resolution and maintaining low pixel occupancy per channel. The spatial resolution improves with a decreased pixel size but it degrades with radiation damage. Therefore, prototype sensor modules for the upgrade of the experiments at the HL-LHC need to be tested after being irradiated. This paper describes position resolution measurements on planar prototype sensors with 100 × 25µm2 pixels for the CMS Phase-2 Upgrade. It reviews the dependence of the position resolution on the relative inclination angle between the incoming particle trajectory and the sensor, the charge threshold applied by the readout chip and the bias voltage. A precision setup with three parallel planes of sensors has been used to investigate the performance of sensors irradiated to fluences up to ϕeq=3.6×1015 cm−2. The measurements were performed with a 5GeV electron beam. A spatial resolution of 3.2±0.1µm is found for non-irradiated sensors, at the optimal angle for charge sharing. The resolution is 5.0±0.2µm for a proton-irradiated sensor at ϕeq=2.1×1015 cm−2 and a neutron-irradiated sensor at ϕeq=3.6×1015 cm−2. The extrapolated resolution to infinite beam momentum, where the contribution of multiple scattering can be neglected, has also been evaluated.
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