Search for Double Parton Scattering in the 4 Jet Channel at

Search for Double Parton Scattering in the 4 Jet Channel at
Author:
Publisher:
Total Pages: 4
Release: 1996
Genre:
ISBN:

We have searched for double parton scattering in the 4-jet channel with an integrated luminosity of 4.4 pb−1, collected using the D{O} detector during 1994-1995 Fermilab Collider run at a center of mass energy ((square root)s) of 1.8 TeV. We present the preliminary observation of a statistically significant excess of signal.

Study of Double Parton Scattering Using Four-Jet Scenarios

Study of Double Parton Scattering Using Four-Jet Scenarios
Author: Paolo Gunnellini
Publisher: Springer
Total Pages: 290
Release: 2015-08-24
Genre: Science
ISBN: 3319222139

This thesis addresses in a very new and elegant way several measurements and the extraction of so-called double parton scattering. The new and elegant way lies in the combination of measurements and a very smart extraction of double parton scattering results, which is easy to apply and overcomes many of the technical difficulties of older methods. Many new phenomena in particle physics can be observed when particles are collided at the highest energies; one of the highlights in recent years was the discovery of the Higgs boson at the Large Hadron Collider at CERN. Understanding the production mechanism of the Higgs boson at the LHC requires detailed knowledge of the physics of proton-proton collisions. When the density of partons in the protons becomes large, there is a non-negligible probability that more than one parton participates in the interaction and the so-called double parton scattering becomes important. In some cases very particular final state signatures can be observed, which can be regarded as an indication of such double partonic scattering and where the different interactions can be separated. Such multiple partonic interactions play an important role when precise predictions from known processes are required.

A Study of Four-jet Events and Search for Double Parton Interactions at [radical]

A Study of Four-jet Events and Search for Double Parton Interactions at [radical]
Author:
Publisher:
Total Pages: 5
Release: 1992
Genre:
ISBN:

Kinematic properties of four-jet events in p[bar p] collisions at [radical]s = 1.8 TeV are compared with the predictions of leading order quantum chromodynamics. We place an upper limit on the double parton scattering cross of [sigma][sub DP] 120 nb (95% C.L.) for partons with transverse momenta greater than 18 GeV/c. Defining the effective cross section [sigma][sub eff] through the equation of [sigma][sub eff] = [sigma][sub DP] = [sigma][sub dijet]/([sup 2]/[sigma][sub eff]), where [sigma][sub dijet] is the cross section for two-jets events, the limit [sigma][sub eff] 3.9 mb (95% C.L.) is also placed. Implications for physics at the SSC ([radical]s = 40 TeV) are discussed.

Search for tt̄H Production in the H → bb̅ Decay Channel

Search for tt̄H Production in the H → bb̅ Decay Channel
Author: Marcel Rieger
Publisher: Springer Nature
Total Pages: 217
Release: 2021-02-25
Genre: Science
ISBN: 3030653803

In 1964, a mechanism explaining the origin of particle masses was proposed by Robert Brout, François Englert, and Peter W. Higgs. 48 years later, in 2012, the so-called Higgs boson was discovered in proton-proton collisions recorded by experiments at the LHC. Since then, its ability to interact with quarks remained experimentally unconfirmed. This book presents a search for Higgs bosons produced in association with top quarks tt̄H in data recorded with the CMS detector in 2016. It focuses on Higgs boson decays into bottom quarks H → bb̅ and top quark pair decays involving at least one lepton. In this analysis, a multiclass classification approach using deep learning techniques was applied for the first time. In light of the dominant background contribution from tt̄ production, the developed method proved to achieve superior sensitivity with respect to existing techniques. In combination with searches in different decay channels, the presented work contributed to the first observations of tt̄H production and H → bb̅ decays.