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Soft resummation and hard evolution : Renormalization group methods in effective theories and multi scalar models

Oredsson, Joel LU (2019)
Abstract
This thesis is composed out of five papers that deal with various problems in
theoretical particle physics. While paper I is a precision calculation in an
effective theory of the Standard Model, paper II to V all deal with beyond the
Standard Model physics. Paper IV is a manual for the tools developed during our
work on paper II to V.

Paper I. We calculate the 2-loop soft function for the transverse momentum
spectrum of a color-neutral final state in proton collisions in the framework of
Soft-Collinear-Effective Theory. Also the 2-loop beam functions are derived in
the same framework by a comparison to other works. This framework relies on
rapidity renormalization group equations to resum... (More)
This thesis is composed out of five papers that deal with various problems in
theoretical particle physics. While paper I is a precision calculation in an
effective theory of the Standard Model, paper II to V all deal with beyond the
Standard Model physics. Paper IV is a manual for the tools developed during our
work on paper II to V.

Paper I. We calculate the 2-loop soft function for the transverse momentum
spectrum of a color-neutral final state in proton collisions in the framework of
Soft-Collinear-Effective Theory. Also the 2-loop beam functions are derived in
the same framework by a comparison to other works. This framework relies on
rapidity renormalization group equations to resum logarithms, which gives an
improved handling of theoretical uncertainties in the resummation. With our
result, one can perform next-to-next-leading log resummation of the mentioned
observable.

Paper II. In this paper, we show that there is no need to introduce scalar
kinetic mixing for models containing several identical scalar fields. This is
shown by an explicit 1-loop calculation of the renormalization group equations
using a toy model. The calculation is performed in separate renormalization
schemes; with and without kinetic mixing. We also derive the renormalization
scale dependent transformations that relate each of these schemes to one
another.

Paper III. This paper analyzes how breaking an imposed Z2 symmetry spreads
during renormalization group evolution of the CP~conserved Two-Higgs-Doublet
Model. We derive the 2-loop renormalization group equations and perform
numerical parameter scans of several physical scenarios.

Paper IV. This is a manual for the software 2HDME that was developed to
perform the numerical calculations in paper III. The code can evolve any
Two-Higgs-Doublet Model at 2-loop order and perform many tree-level calculations
such as masses and oblique parameters, but also tests of stability and
unitarity.

Paper V. In this paper, we use 2HDME in a similar way to paper III, but
this time with the CP~violating Two-Higgs-Doublet Model. We also implement a
calculation of the electron's electric dipole moment that we use to constrain
the amount of CP~violation. We perform several numerical parameter scans of
scenarios with different levels of Z2 symmetry breaking. (Less)
Abstract (Swedish)
This thesis is composed out of five papers that deal with various problems in
theoretical particle physics. While paper I is a precision calculation in an
effective theory of the Standard Model, paper II to V all deal with beyond the
Standard Model physics. Paper IV is a manual for the tools developed during our
work on paper II to V.

Paper I. We calculate the 2-loop soft function for the transverse momentum
spectrum of a color-neutral final state in proton collisions in the framework of
Soft-Collinear-Effective Theory. Also the 2-loop beam functions are derived in
the same framework by a comparison to other works. This framework relies on
rapidity renormalization group equations to resum... (More)
This thesis is composed out of five papers that deal with various problems in
theoretical particle physics. While paper I is a precision calculation in an
effective theory of the Standard Model, paper II to V all deal with beyond the
Standard Model physics. Paper IV is a manual for the tools developed during our
work on paper II to V.

Paper I. We calculate the 2-loop soft function for the transverse momentum
spectrum of a color-neutral final state in proton collisions in the framework of
Soft-Collinear-Effective Theory. Also the 2-loop beam functions are derived in
the same framework by a comparison to other works. This framework relies on
rapidity renormalization group equations to resum logarithms, which gives an
improved handling of theoretical uncertainties in the resummation. With our
result, one can perform next-to-next-leading log resummation of the mentioned
observable.

Paper II. In this paper, we show that there is no need to introduce scalar
kinetic mixing for models containing several identical scalar fields. This is
shown by an explicit 1-loop calculation of the renormalization group equations
using a toy model. The calculation is performed in separate renormalization
schemes; with and without kinetic mixing. We also derive the renormalization
scale dependent transformations that relate each of these schemes to one
another.

Paper III. This paper analyzes how breaking an imposed Z2 symmetry spreads
during renormalization group evolution of the CP~conserved Two-Higgs-Doublet
Model. We derive the 2-loop renormalization group equations and perform
numerical parameter scans of several physical scenarios.

Paper IV. This is a manual for the software 2HDME that was developed to
perform the numerical calculations in paper III. The code can evolve any
Two-Higgs-Doublet Model at 2-loop order and perform many tree-level calculations
such as masses and oblique parameters, but also tests of stability and
unitarity.

Paper V. In this paper, we use 2HDME in a similar way to paper III, but
this time with the CP~violating Two-Higgs-Doublet Model. We also implement a
calculation of the electron's electric dipole moment that we use to constrain
the amount of CP~violation. We perform several numerical parameter scans of
scenarios with different levels of Z2 symmetry breaking. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Professor Plehn, Tilman, Heidelberg University, Heidelberg, Germany
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Higgs, Particle physics, two-Higgs-doublet model, Soft-Collinear-Effective Theory, Renormalization
pages
226 pages
publisher
Department of Astronomy and Theoretical Physics, Lund University
defense location
Rydbergssalen, Fysicum, Sölvegatan 14A, Lund
defense date
2019-10-25 10:00:00
ISBN
978-91-7895-255-7
978-91-7895-256-4
language
English
LU publication?
yes
id
0369596e-4432-4de3-b968-73b051b0d930
date added to LUP
2019-09-30 12:22:54
date last changed
2019-10-01 11:39:12
@phdthesis{0369596e-4432-4de3-b968-73b051b0d930,
  abstract     = {{This thesis is composed out of five papers that deal with various problems in<br/>theoretical particle physics. While paper I is a precision calculation in an<br/>effective theory of the Standard Model, paper II to V all deal with beyond the<br/>Standard Model physics. Paper IV is a manual for the tools developed during our<br/>work on paper II to V.<br/><br/>Paper I. We calculate the 2-loop soft function for the transverse momentum<br/>spectrum of a color-neutral final state in proton collisions in the framework of<br/>Soft-Collinear-Effective Theory. Also the 2-loop beam functions are derived in<br/>the same framework by a comparison to other works. This framework relies on<br/>rapidity renormalization group equations to resum logarithms, which gives an<br/>improved handling of theoretical uncertainties in the resummation. With our<br/>result, one can perform next-to-next-leading log resummation of the mentioned<br/>observable.<br/><br/>Paper II. In this paper, we show that there is no need to introduce scalar<br/>kinetic mixing for models containing several identical scalar fields. This is<br/>shown by an explicit 1-loop calculation of the renormalization group equations<br/>using a toy model. The calculation is performed in separate renormalization<br/>schemes; with and without kinetic mixing. We also derive the renormalization<br/>scale dependent transformations that relate each of these schemes to one<br/>another. <br/><br/>Paper III. This paper analyzes how breaking an imposed Z2 symmetry spreads<br/>during renormalization group evolution of the CP~conserved Two-Higgs-Doublet<br/>Model. We derive the 2-loop renormalization group equations and perform<br/>numerical parameter scans of several physical scenarios.<br/><br/>Paper IV. This is a manual for the software 2HDME that was developed to<br/>perform the numerical calculations in paper III. The code can evolve any<br/>Two-Higgs-Doublet Model at 2-loop order and perform many tree-level calculations<br/>such as masses and oblique parameters, but also tests of stability and<br/>unitarity.<br/><br/>Paper V. In this paper, we use 2HDME in a similar way to paper III, but<br/>this time with the CP~violating Two-Higgs-Doublet Model. We also implement a<br/>calculation of the electron's electric dipole moment that we use to constrain<br/>the amount of CP~violation. We perform several numerical parameter scans of<br/>scenarios with different levels of Z2 symmetry breaking.}},
  author       = {{Oredsson, Joel}},
  isbn         = {{978-91-7895-255-7}},
  keywords     = {{Higgs; Particle physics; two-Higgs-doublet model; Soft-Collinear-Effective Theory; Renormalization}},
  language     = {{eng}},
  publisher    = {{Department of Astronomy and Theoretical Physics, Lund University}},
  school       = {{Lund University}},
  title        = {{Soft resummation and hard evolution : Renormalization group methods in effective theories and multi scalar models}},
  url          = {{https://lup.lub.lu.se/search/files/70154370/e_spik_ex_joel.pdf}},
  year         = {{2019}},
}