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@PHDTHESIS{Schlaffer:224253,
author = {Schlaffer, Matthias},
title = {{B}oosted {S}earches {F}or {N}ew {P}hysics {A}t {T}he
{LHC}},
issn = {1435-8085},
school = {Universität Hamburg},
type = {Dissertation},
address = {Hamburg},
publisher = {Verlag Deutsches Elektronen-Synchrotron},
reportid = {PUBDB-2015-03458, DESY-THESIS-2015-036},
series = {DESY-THESIS},
pages = {121},
year = {2015},
note = {Dissertation, Universität Hamburg, 2015},
abstract = {During the first run of the LHC, no apparent signs of new
physics beyond the StandardModel were discovered, but rather
the Standard Model-like properties of the Higgs
particleconfirmed. Therefore, new and powerful methods are
needed to disclose the traces of newphysics, which is
expected to be at the TeV scale in order to solve the
hierarchy problem.In this thesis, we propose two
complementary strategies for the quest for new physics atthe
LHC. First, we show how a very boosted Higgs in association
with a hard jet can beused to determine the important top
Yukawa coupling in gluon fusion. In the inclusive
gluonfusion process this is not feasible since possible
deviations from its Standard Model value arecombined and can
even cancel with the effective Higgs-gluon interaction
mediated by newtop partners. This cancellation is motivated
within minimal composite Higgs models butalso in certain
regions of the MSSM parameter space and can lead to a
Standard Model-likeinclusive cross section that allows no
conclusions on the mass spectrum of the new physics.We work
out in detail how this degeneracy can be broken in the
boosted Higgs channel andfind that even in the worst case
scenario with a Standard Model-like inclusive cross
section,the top Yukawa coupling can be constrained to
0.8–1.3 times its Standard Model value $at95\%$ CL with an
integrated luminosity of 3 000 fb −1 .The second strategy
is targeted at direct stop and sbottom searches in the fully
hadronictop decay channel. Since the stop, sbottom and
neutralino masses are unknown, verydifferent event shapes
are imaginable, ranging from unboosted top quarks and low
missingenergy to highly boosted top quarks and large missing
energy in the final state. In order tocover a wide range of
possible event shapes and consequently stop, sbottom, and
neutralinomasses, we combine several top taggers based on
jet substructure techniques to obtain ascale invariant
search strategy. The performance of this approach is shown
in a colliderstudy where we find that stops with masses up
to about 1 100 GeV can be excluded at $95\%CL$ with an
integrated luminosity of 100 fb −1 .},
cin = {T},
cid = {I:(DE-H253)T-20120731},
pnm = {611 - Fundamental Particles and Forces (POF3-611) / PHGS,
VH-GS-500 - PIER Helmholtz Graduate School
$(2015_IFV-VH-GS-500)$},
pid = {G:(DE-HGF)POF3-611 / $G:(DE-HGF)2015_IFV-VH-GS-500$},
experiment = {EXP:(DE-MLZ)NOSPEC-20140101},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
doi = {10.3204/DESY-THESIS-2015-036},
url = {https://bib-pubdb1.desy.de/record/224253},
}