After the Higgs boson discovery at the LHC, a lot of additional measurements should be performed to understand in detail the properties of the observed particle. Searches for CP violation in ...different physics sectors are one of the most promising and important parts of these measurements. Associated Higgs boson production in pp collisions can be a powerful tool for searches for possible CP violation in the Higgs sector. In this paper, the study of CP sensitive observables constructed for a four lepton final state is presented. It is shown that azimuthal angle distributions of leptons in this process demonstrate a strong sensitivity to CP violation at the current limits on Higgs boson coupling parameters and can reveal a genuine mechanism of CP violation.
In this article, the prospects for studying the tensor structure of the HZZ vertex with the LHC experiments are presented. The structure of tensor couplings in Higgs di-boson decays is investigated ...by measuring the asymmetries and by studying the shapes of the final state angular distributions. The expected background contributions, detector resolution, and trigger and selection efficiencies are taken into account. The potential of the LHC experiments to discover sizeable non-Standard Model contributions to the HZZ vertex with 300 and 3000 fb super(-1) is demonstrated.
After the Higgs boson discovery at the LHC, a lot of additional measurements should be performed to understand in details the properties of the observed particle. These measurements include cross ...sections measurements, couplings measurements, studies of the interaction vertex structures etc. One of the most perspective subjects to study is the kinematics of the production jets, associated with the Higgs boson. It is demonstrated, that the kinematic correlations of such jets can be used to distinguish different production channels of Higgs boson: gluon-gluon fusion (ggF) and vector boson fusion (VBF). Such separation plays an important role because possible beyond the Standard Model contributions in ggF and VBF channels lead to different effects, which should be taken into account in searches for BSM physics.
We study observables sensitive to tensor structure of interactions of a hypothetical heavy spin-0 particle. It is assumed that the interactions of this particle are primary with photons; interactions ...with vector bosons
gg
,
WW
,
ZZ
, and quarks
t
t
¯
are suppressed. The above assumptions favor the production of this hypothetical particle through the vector boson fusion mechanism structurally dominated by γγ and γ
Z
interactions. This particle will be produced in association with two light quarks. It is shown that the difference in azimuthal angle between the tagging jets provides an observable sensitive to the
CP
properties of this hypothetical particle.
We study observables sensitive to tensor structure of interactions of a hypothetical heavy spin-0 boson. It is assumed that interactions of this particle are dominated by interactions with photons. ...The interactions with other vector bosons and quarks are supposed to be suppressed. The above assumptions favor the production of this hypothetical particle through the vector boson fusion mechanism structurally dominated by the photon and Z-interactions. This particle will be produced in association with two light quarks. It is shown that the azimuthal angle difference between the tagging jets provides an observable to probe the tensor structure of the interaction vertices of such hypothetical particle.
These proceedings present the method and performance of primary vertex reconstruction at the ATLAS experiment during Runs 1 and 2 at the LHC. The studies presented focus on data taken during 2012 at ...a centre-of-mass energy of s=8TeV, and during 2015-2016 at s=13TeV. Some predictions toward future runs are also presented. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed.
The ATLAS Pixel detector is currently measuring particle positions at 8 TeV proton-proton collisions at the LHC. In the dense environment of jets with high transverse momenta produced in these events ...the separation between particles becomes small, such that their respective charge deposited are reconstructed as single clusters. A Neural Network (NN)-based clustering algorithm has been developed to identify such merged clusters. By using all cluster information, the NN is ideal to estimate the particle multiplicity and for each of the estimated number of particles, the position with its uncertainty. As a result of the NN reconstruction, the number of hits shared by several tracks is strongly reduced. Furthermore, the impact parameter improves by about 15% which indicates boosted prospects for physics analysis.
The reconstruction of vertices corresponding to proton-proton collisions in ATLAS is an essential element of event reconstruction used in many performance studies and physics analyses. During Run-1 ...of the LHC, ATLAS has employed an iterative approach to vertex finding. In order to improve the flexibility of the algorithm and ensure continued performance for very high numbers of simultaneous collisions in Run-2 of the LHC and beyond, a new approach to seeding vertex finding has been developed inspired by image reconstruction techniques. This note provides a brief outline of how reconstructed tracks are used to create an image of likely vertex collisions in an event, describes the implementation in the ATLAS software, and presents some preliminary results of the performance of the algorithm in simulation approximating early Run-2 conditions.
The CMS experiment at the (LHC) includes a hybrid silicon pixel detector for the reconstruction of charged tracks and of the interaction vertices. The barrel region consists of n-in-n sensors with
...100
×
150
μ
m
2
cell size processed on diffusion oxygenated float zone silicon. A biasing grid is implemented and pixel isolation is achieved with the moderated p-spray technique. An extensive test program was carried out on the H
2 beam line of the CERN-SPS. In this paper we describe the sensor layout, the beam test setup and the results obtained with both irradiated and non-irradiated prototype devices. Measurements of charge collection, hit detection efficiency, Lorentz angle and spatial resolution are presented.
In this paper a new method is described for determining the non-diffractive part of the inelastic proton–proton cross section, at the LHC centre of mass energy of 14 TeV. The method is based on ...counting the number of inelastic proton–proton interactions in the collision regions. According to a preliminary investigation, this measurement will be best suited for the initial low luminosity phase of the LHC. Knowledge of the proton–proton luminosity is likely to dominate the measurement uncertainty.
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