CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

An embedding technique to determine ττ backgrounds in proton-proton collision data

An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe

Performance of missing transverse momentum reconstruction in proton-proton collisions at root s=13 TeV using the CMS detector

The performance of missing transverse momentum ((p) over right arrow (miss)(T)) reconstruction algorithms for the CMS experiment is presented, using proton-proton collisions at a center-of-mass energy of 13 TeV, collected at the CERN LHC in 2016. The data sample corresponds to an integrated luminosity of 35.9 fb(-1). The results include measurements of the scale and resolution of (p) over right arrow (miss)(T), and detailed studies of events identified with anomalous (p) over right arrow (miss)(T). The performance is presented of a (p) over right arrow (miss)(T) reconstruction algorithm that mitigates the effects of multiple proton-proton interactions, using the "pileup per particle identification" method. The performance is shown of an algorithm used to estimate the compatibility of the reconstructed (p) over right arrow (miss)(T) with the hypothesis that it originates from resolution effects.Peer reviewe

Measurement of the Z y production cross section in pp collisions at 8 TeV and search for anomalous triple gauge boson couplings

The cross section for the production of Z γ in proton-proton collisions at 8 TeV is measured based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 19.5 fb −1 . Events with an oppositely-charged pair of muons or electrons together with an isolated photon are selected. The differential cross section as a function of the photon transverse momentum is measured inclusively and exclusively, where the exclusive selection applies a veto on central jets. The observed cross sections are compatible with the expectations of next-to-next-to-leading-order quantum chromodynamics. Limits on anomalous triple gauge couplings of ZZ γ and Z γγ are set that improve on previous experimental results obtained with the charged lepton decay modes of the Z boson

Using three-band model to retrieve chlorophyll-A of Yantai coastal waters

It is challenging that accurate assessment of chlorophyll-A concentration by remote sensing in coastal waters. Chla concentration is commonly retrieved by blue-green ratio in open ocean waters. And this method is efficient in open ocean waters. But this method is confined when applied to coastal or inland waters, because of abundant variable CDOM and tripton. It is very difficult to retrieve chla of coastal or estuary waters because of overlap of absorption and backscattering caused by CDOM and tripton. Dall€™Olmo et al put forward a semi-analytical retrieval model of chla, three-band model. The conceptual three-band model has been successfully applied to estimate chla in turbid and eutrophic waters by tuning the band position in accordance with the spectral properties.The aim of this paper is to testify the three-band model that could resolve this problem. The three-band model was tuned in accord with optical properties and the bands were optimized for accurate estimation. Finally, we found a good linear relationship between chlorophyll-A and three-band model, with the determination coefficient of 0.63 and the RMSE of 2.22μg·L-1. Furthermore, the in situ spectral data was averaged to the band range of MERIS (band7, band9 and band10) and developed a simulated threeband model. A good linear relationship could be found between [(B7-1-B9-1)×B10] and chlorophyll-a, with the determination coefficient of 0.59 and the RMSE of 0.72μg·L-1. The findings demonstrated that the three-band model of MERIS could be applied to retrieve chlorophyll-A concentration of Yantai coastal waters