Search NASA⌕ Search

Engineering topics

Greiner, Nicolas

Publications and source records attributed to Greiner, Nicolas.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Full mass dependence in Higgs boson production in association with jets at the LHC and FCC

The first computation of Higgs production in association with three jets at NLO in QCD has recently been performed using the effective theory, where the top quark is treated as an infinitely heavy particle and integrated out. This approach is restricted to the regions in phase space where the typical scales are not larger than the top quark mass. Here we investigate this statement at a quantitative level by calculating the leading-order contributions to the production of a Standard Model Higgs boson in association with up to three jets taking full top-quark and bottom-quark mass dependence into account. We find that the transverse momentum of the hardest particle or jet plays a key role in the breakdown of the effective theory predictions, and that discrepancies can easily reach an order of magnitude for transverse momenta of about 1 TeV. The impact of bottom-quark loops is found to be visible in the small transverse momentum region, leading to corrections of up to 5 percent. Lastly, we further study the impact of mass corrections when VBF selection cuts are applied and when the center-of-mass energy is increased to 100 TeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Phenomenological analysis of Higgs boson production through gluon fusion in association with jets

We present a detailed phenomenological analysis of the production of a Standard Model Higgs boson in association with up to three jets. We consider the gluon fusion channel using an effective theory in the large top-quark mass limit. Higgs boson production in gluon fusion constitutes an irreducible background to the vector boson fusion (VBF) process; hence the precise knowledge of its characteristics is a prerequisite for any measurement in the VBF channel. The calculation is carried out at next-to-leading order (NLO) in QCD in a fully automated way by combining the two programs GoS AM and SHERPA. We present numerical results for a large variety of observables for both standard cuts and VBF selection cuts.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

hhjj production at the LHC

The search for di-Higgs production at the LHC in order to set limits on the Higgs trilinear coupling and constraints on new physics is one of the main motivations for the LHC high-luminosity phase. Recent experimental analyses suggest that such analyses will only be successful if information from a range of channels is included. We therefore investigate di-Higgs production in association with two hadronic jets and give a detailed discussion of both the gluon- and the weak boson-fusion (WBF) contributions, with a particular emphasis on the phenomenology with modified Higgs trilinear and quartic gauge couplings. We perform a detailed investigation of the full hadronic final state and find that hhjj production should add sensitivity to a di-Higgs search combination at the HL-LHC with 3 ab -1 . Since the WBF and GF contributions are sensitive to different sources of physics beyond the Standard Model, we devise search strategies to disentangle and isolate these production modes. In addition, while gluon fusion remains non-negligible in WBF-type selections, sizeable new physics contributions to the latter can still be constrained. As an example of the latter point we investigate the sensitivity that can be obtained for a measurement of the quartic Higgs–gauge boson couplings.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Effective field theory: A modern approach to anomalous couplings

We advocate an effective field theory approach to anomalous couplings. The effective field theory approach is the natural way to extend the standard model such that the gauge symmetries are respected. It is general enough to capture any physics beyond the standard model, yet also provides guidance as to the most likely place to see the effects of new physics. The effective field theory approach also clarifies that one need not be concerned with the violation of unitarity in scattering processes at high energy. We apply these ideas to pair production of electroweak vector bosons. -- Highlights: •We discuss the advantages of effective field theories compared to anomalous couplings. •We show that one need not be concerned with unitarity violation at high energy. •We discuss the application of effective field theory to weak boson physics.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗