{"id":{"repo_id":"freiburg-diss","oai_identifier":"oai:freidok.uni-freiburg.de:2004"},"canonical_url":"https://search.dev.ndltd.org/etd/freiburg-diss/oai:freidok.uni-freiburg.de:2004","repository":{"repo_id":"freiburg-diss","name":"University of Freiburg","base_url":"https://freidok.uni-freiburg.de/oai/oai2.php"},"display":{"title":"Three loop corrections to electroweak precision observables in the large Higgs mass limit","abstract":"The Glashow-Salam-Weinberg Model is presently
the most comprehensive formulation of a theory of the unified
electroweak interaction, theoretically consistent and in agreement
with all experimentally known phenomena of electroweak origin,
with the exception of the evidence of neutrino mixing.
During the eleven years of data collection at the Large Electron Positron
Collider (LEP) at CERN in Geneva, the Electroweak sector of the Standard
Model (EWSM), based on a spontaneously broken SU(2)_L \\times U(1)_Y gauge
symmetry, has been experimentally tested at the level
of quantum corrections by precise measurement of several observables.
The direct observation of the predicted top quark at the proton-antiproton
collider Tevatron at Fermilab in 1994 with a mass determination
(now at m_t= 174.3+- 3.4 GeV) that impressively
matches the mass range indirectly obtained via the radiative corrections calculated in the framework of the Electroweak Standard Model, strengthened
our belief in it as the theory that correctly describes electroweak
phenomena.
The only ingredient predicted by this model that has not
been seen yet is the Higgs particle. The direct search
at LEP has only provided us with a lower limit on the mass
of the Standard Model Higgs boson excluding the region below 114.4 GeV.
The precision of present day experiments even makes it possible to put
limits on the Higgs mass through its influence in radiative corrections,
which grow logarithmically with the Higgs boson mass at
the one loop level. The global fit of
the experimental data to the Standard Model favors a light Higgs boson
( m_H less or equal to 285 GeV one-sided 95 % Confidence Level (CL)).
However the situation is not completely satisfactory, as there is a
difference of about 3.2 \\sigma between the two most precise
determinations of the electroweak mixing angle , ie the one
based on the measurement of the b-quark forward-backward asymmetry
A_{FB}^{0,b} at LEP on the one hand, and the one based on measurements of
the leptonic asymmetry parameter A_l at SLD on the other.
The value of the Higgs mass preferred by the b-quark data is around 0.5 TeV,
while the leptonic asymmetry data and the
W-boson mass point to a value which is slightly below
the lower bound from the direct searches. With the recent measurements
of the W-mass and top mass from the Tevatron this is well within
statistics.
The discrepancy between these two precise measurements suggests that
the possibility of a heavy Higgs boson is not ruled out.
Since the center of mass energies of present colliders do not allow
to probe the region of a heavy Higgs boson,
the sensitivity of radiative corrections
to physical observables to a heavy Higgs boson mass becomes an important
tool in setting upper and lower limits on m_H.
For a light Higgs boson, the Higgs mass dependence
of the theoretical predictions is mainly due to one-loop radiative
corrections to the gauge boson propagators. These one-loop corrections
depend on m_H logarithmically. However,
because the Higgs self-interaction \\lambda is proportional to
m_H^2, there are higher order radiative corrections which grow like
powers of m_H in the limit m_H going to infinity, eventually overcoming
their relative suppression by powers of the fine
structure constant \\alpha. Such higher order
corrections could become important if the Higgs boson is very heavy.
At the two-loop level, the leading corrections are proportional to
m_H^2, but the numerical coefficient of these terms turns out to
be very small,
and therefore, they are not important for m_H less than a few TeV.
However, it has been suggested that the smallness of the two-loop corrections
may be somewhat accidental. If this is true, then one
may expect larger corrections to appear at the three loop level.
In this thesis, we investigate the leading three-loop corrections
to three electroweak observables, namely the electroweak
\\rho-parameter, the effective leptonic weak mixing angle
defined in terms of couplings of the Z-boson to leptons,
and the W-boson mass. This investigation will allow us to check whether
a heavy Higgs boson could behave like a light Higgs boson by giving
a similar effect in loop corrections to the previously mentioned
electroweak observables. The sign and the size of the leading three-loop
corrections to these observables play a crucial role in either confirming
this possibility or ruling it out completely.","abstract_html":"The Glashow-Salam-Weinberg Model is presently <br>the most comprehensive formulation of a theory of the unified <br>electroweak interaction, theoretically consistent and in agreement <br>with all experimentally known phenomena of electroweak origin, <br>with the exception of the evidence of neutrino mixing. <br>During the eleven years of data collection at the Large Electron Positron <br>Collider (LEP) at CERN in Geneva, the Electroweak sector of the Standard <br>Model (EWSM), based on a spontaneously broken SU(2)_L \\times U(1)_Y gauge <br>symmetry, has been experimentally tested at the level <br>of quantum corrections by precise measurement of several observables. <br>The direct observation of the predicted top quark at the proton-antiproton <br>collider Tevatron at Fermilab in 1994 with a mass determination <br>(now at m_t= 174.3+- 3.4 GeV) that impressively <br>matches the mass range indirectly obtained via the radiative corrections calculated in the framework of the Electroweak Standard Model, strengthened <br>our belief in it as the theory that correctly describes electroweak <br>phenomena. <br>The only ingredient predicted by this model that has not <br>been seen yet is the Higgs particle. The direct search <br>at LEP has only provided us with a lower limit on the mass <br>of the Standard Model Higgs boson excluding the region below 114.4 GeV. <br>The precision of present day experiments even makes it possible to put <br>limits on the Higgs mass through its influence in radiative corrections, <br>which grow logarithmically with the Higgs boson mass at <br>the one loop level. The global fit of <br>the experimental data to the Standard Model favors a light Higgs boson <br>( m_H less or equal to 285 GeV one-sided 95 % Confidence Level (CL)). <br>However the situation is not completely satisfactory, as there is a <br>difference of about 3.2 \\sigma between the two most precise <br>determinations of the electroweak mixing angle , ie the one <br>based on the measurement of the b-quark forward-backward asymmetry <br>A_{FB}^{0,b} at LEP on the one hand, and the one based on measurements of <br>the leptonic asymmetry parameter A_l at SLD on the other. <br>The value of the Higgs mass preferred by the b-quark data is around 0.5 TeV, <br>while the leptonic asymmetry data and the <br>W-boson mass point to a value which is slightly below <br>the lower bound from the direct searches. With the recent measurements <br>of the W-mass and top mass from the Tevatron this is well within <br>statistics. <br>The discrepancy between these two precise measurements suggests that <br>the possibility of a heavy Higgs boson is not ruled out. <br>Since the center of mass energies of present colliders do not allow <br>to probe the region of a heavy Higgs boson, <br>the sensitivity of radiative corrections <br>to physical observables to a heavy Higgs boson mass becomes an important <br>tool in setting upper and lower limits on m_H. <br>For a light Higgs boson, the Higgs mass dependence <br>of the theoretical predictions is mainly due to one-loop radiative <br>corrections to the gauge boson propagators. These one-loop corrections <br>depend on m_H logarithmically. However, <br>because the Higgs self-interaction \\lambda is proportional to <br>m_H^2, there are higher order radiative corrections which grow like <br>powers of m_H in the limit m_H going to infinity, eventually overcoming <br>their relative suppression by powers of the fine <br>structure constant \\alpha. Such higher order <br>corrections could become important if the Higgs boson is very heavy. <br>At the two-loop level, the leading corrections are proportional to <br>m_H^2, but the numerical coefficient of these terms turns out to <br>be very small, <br>and therefore, they are not important for m_H less than a few TeV. <br>However, it has been suggested that the smallness of the two-loop corrections <br>may be somewhat accidental. If this is true, then one <br>may expect larger corrections to appear at the three loop level. <br>In this thesis, we investigate the leading three-loop corrections <br>to three electroweak observables, namely the electroweak <br>\\rho-parameter, the effective leptonic weak mixing angle <br>defined in terms of couplings of the Z-boson to leptons, <br>and the W-boson mass. This investigation will allow us to check whether <br>a heavy Higgs boson could behave like a light Higgs boson by giving <br>a similar effect in loop corrections to the previously mentioned <br>electroweak observables. The sign and the size of the leading three-loop <br>corrections to these observables play a crucial role in either confirming <br>this possibility or ruling it out completely.","abstract_has_math":false,"creators":["Boughezal, Radja"],"institution":null,"degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["Bij, Jochum van der"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":null,"date_issued":"","date_published":null,"updated_at":"2026-07-24T02:22:33Z","subjects":["radiative corrections, electroweak physics"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://freidok.uni-freiburg.de/data/2004","outbound_label":"Repository record","outbound_source":"source_url"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Bij, Jochum van der"]},{"key":"dc:creator","label":"Author","values":["Boughezal, Radja"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:type","label":"Dc Type","values":["DoctoralThesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["radiative corrections, electroweak physics"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The Glashow-Salam-Weinberg Model is presently
the most comprehensive formulation of a theory of the unified
electroweak interaction, theoretically consistent and in agreement
with all experimentally known phenomena of electroweak origin,
with the exception of the evidence of neutrino mixing.
During the eleven years of data collection at the Large Electron Positron
Collider (LEP) at CERN in Geneva, the Electroweak sector of the Standard
Model (EWSM), based on a spontaneously broken SU(2)_L \\times U(1)_Y gauge
symmetry, has been experimentally tested at the level
of quantum corrections by precise measurement of several observables.
The direct observation of the predicted top quark at the proton-antiproton
collider Tevatron at Fermilab in 1994 with a mass determination
(now at m_t= 174.3+- 3.4 GeV) that impressively
matches the mass range indirectly obtained via the radiative corrections calculated in the framework of the Electroweak Standard Model, strengthened
our belief in it as the theory that correctly describes electroweak
phenomena.
The only ingredient predicted by this model that has not
been seen yet is the Higgs particle. The direct search
at LEP has only provided us with a lower limit on the mass
of the Standard Model Higgs boson excluding the region below 114.4 GeV.
The precision of present day experiments even makes it possible to put
limits on the Higgs mass through its influence in radiative corrections,
which grow logarithmically with the Higgs boson mass at
the one loop level. The global fit of
the experimental data to the Standard Model favors a light Higgs boson
( m_H less or equal to 285 GeV one-sided 95 % Confidence Level (CL)).
However the situation is not completely satisfactory, as there is a
difference of about 3.2 \\sigma between the two most precise
determinations of the electroweak mixing angle , ie the one
based on the measurement of the b-quark forward-backward asymmetry
A_{FB}^{0,b} at LEP on the one hand, and the one based on measurements of
the leptonic asymmetry parameter A_l at SLD on the other.
The value of the Higgs mass preferred by the b-quark data is around 0.5 TeV,
while the leptonic asymmetry data and the
W-boson mass point to a value which is slightly below
the lower bound from the direct searches. With the recent measurements
of the W-mass and top mass from the Tevatron this is well within
statistics.
The discrepancy between these two precise measurements suggests that
the possibility of a heavy Higgs boson is not ruled out.
Since the center of mass energies of present colliders do not allow
to probe the region of a heavy Higgs boson,
the sensitivity of radiative corrections
to physical observables to a heavy Higgs boson mass becomes an important
tool in setting upper and lower limits on m_H.
For a light Higgs boson, the Higgs mass dependence
of the theoretical predictions is mainly due to one-loop radiative
corrections to the gauge boson propagators. These one-loop corrections
depend on m_H logarithmically. However,
because the Higgs self-interaction \\lambda is proportional to
m_H^2, there are higher order radiative corrections which grow like
powers of m_H in the limit m_H going to infinity, eventually overcoming
their relative suppression by powers of the fine
structure constant \\alpha. Such higher order
corrections could become important if the Higgs boson is very heavy.
At the two-loop level, the leading corrections are proportional to
m_H^2, but the numerical coefficient of these terms turns out to
be very small,
and therefore, they are not important for m_H less than a few TeV.
However, it has been suggested that the smallness of the two-loop corrections
may be somewhat accidental. If this is true, then one
may expect larger corrections to appear at the three loop level.
In this thesis, we investigate the leading three-loop corrections
to three electroweak observables, namely the electroweak
\\rho-parameter, the effective leptonic weak mixing angle
defined in terms of couplings of the Z-boson to leptons,
and the W-boson mass. This investigation will allow us to check whether
a heavy Higgs boson could behave like a light Higgs boson by giving
a similar effect in loop corrections to the previously mentioned
electroweak observables. The sign and the size of the leading three-loop
corrections to these observables play a crucial role in either confirming
this possibility or ruling it out completely."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Three loop corrections to electroweak precision observables in the large Higgs mass limit","Drei Schleifen Korrekturen zu Elektroschwachen Observablen im Limes grosser Higgs Masse"]}]}],"canonical_facts":{"dc:contributor":["Bij, Jochum van der"],"dc:creator":["Boughezal, Radja"],"dc:description.abstract":["The Glashow-Salam-Weinberg Model is presently
the most comprehensive formulation of a theory of the unified
electroweak interaction, theoretically consistent and in agreement
with all experimentally known phenomena of electroweak origin,
with the exception of the evidence of neutrino mixing.
During the eleven years of data collection at the Large Electron Positron
Collider (LEP) at CERN in Geneva, the Electroweak sector of the Standard
Model (EWSM), based on a spontaneously broken SU(2)_L \\times U(1)_Y gauge
symmetry, has been experimentally tested at the level
of quantum corrections by precise measurement of several observables.
The direct observation of the predicted top quark at the proton-antiproton
collider Tevatron at Fermilab in 1994 with a mass determination
(now at m_t= 174.3+- 3.4 GeV) that impressively
matches the mass range indirectly obtained via the radiative corrections calculated in the framework of the Electroweak Standard Model, strengthened
our belief in it as the theory that correctly describes electroweak
phenomena.
The only ingredient predicted by this model that has not
been seen yet is the Higgs particle. The direct search
at LEP has only provided us with a lower limit on the mass
of the Standard Model Higgs boson excluding the region below 114.4 GeV.
The precision of present day experiments even makes it possible to put
limits on the Higgs mass through its influence in radiative corrections,
which grow logarithmically with the Higgs boson mass at
the one loop level. The global fit of
the experimental data to the Standard Model favors a light Higgs boson
( m_H less or equal to 285 GeV one-sided 95 % Confidence Level (CL)).
However the situation is not completely satisfactory, as there is a
difference of about 3.2 \\sigma between the two most precise
determinations of the electroweak mixing angle , ie the one
based on the measurement of the b-quark forward-backward asymmetry
A_{FB}^{0,b} at LEP on the one hand, and the one based on measurements of
the leptonic asymmetry parameter A_l at SLD on the other.
The value of the Higgs mass preferred by the b-quark data is around 0.5 TeV,
while the leptonic asymmetry data and the
W-boson mass point to a value which is slightly below
the lower bound from the direct searches. With the recent measurements
of the W-mass and top mass from the Tevatron this is well within
statistics.
The discrepancy between these two precise measurements suggests that
the possibility of a heavy Higgs boson is not ruled out.
Since the center of mass energies of present colliders do not allow
to probe the region of a heavy Higgs boson,
the sensitivity of radiative corrections
to physical observables to a heavy Higgs boson mass becomes an important
tool in setting upper and lower limits on m_H.
For a light Higgs boson, the Higgs mass dependence
of the theoretical predictions is mainly due to one-loop radiative
corrections to the gauge boson propagators. These one-loop corrections
depend on m_H logarithmically. However,
because the Higgs self-interaction \\lambda is proportional to
m_H^2, there are higher order radiative corrections which grow like
powers of m_H in the limit m_H going to infinity, eventually overcoming
their relative suppression by powers of the fine
structure constant \\alpha. Such higher order
corrections could become important if the Higgs boson is very heavy.
At the two-loop level, the leading corrections are proportional to
m_H^2, but the numerical coefficient of these terms turns out to
be very small,
and therefore, they are not important for m_H less than a few TeV.
However, it has been suggested that the smallness of the two-loop corrections
may be somewhat accidental. If this is true, then one
may expect larger corrections to appear at the three loop level.
In this thesis, we investigate the leading three-loop corrections
to three electroweak observables, namely the electroweak
\\rho-parameter, the effective leptonic weak mixing angle
defined in terms of couplings of the Z-boson to leptons,
and the W-boson mass. This investigation will allow us to check whether
a heavy Higgs boson could behave like a light Higgs boson by giving
a similar effect in loop corrections to the previously mentioned
electroweak observables. The sign and the size of the leading three-loop
corrections to these observables play a crucial role in either confirming
this possibility or ruling it out completely."],"dc:format.medium":["application/pdf"],"dc:subject":["radiative corrections, electroweak physics"],"dc:title":["Three loop corrections to electroweak precision observables in the large Higgs mass limit","Drei Schleifen Korrekturen zu Elektroschwachen Observablen im Limes grosser Higgs Masse"],"dc:type":["DoctoralThesis"]},"updated_at":"2026-07-24T02:22:33Z"}