22 research outputs found
Phenomenology of the Higgs and Flavour Physics in the Standard Model and Beyond
In dieser Arbeit werden einige zukĂŒnftige Aspekte der Higgs-Messungen ein Jahrzehnt
nach seiner Entdeckung untersucht, wobei der Schwerpunkt auf dem Potenzial
fĂŒr zukĂŒnftige LĂ€ufe des Large Hadron Collider (LHC) liegt. Insbesondere sollen
anspruchsvolle Kopplungen des Higgs, wie seine Selbstkopplung und die Wechselwirkung
mit leichten Quarks, untersucht werden. Der erste Teil gibt einen Ăberblick
ĂŒber die Higgs-Physik innerhalb der effektiven Feldtheorie des Standardmodells
(SMEFT). Der zweite Teil befasst sich mit der Single-Higgs-Produktion, beginnend
mit einer Zweischleifenberechnung der Gluonenfusionskomponente von Zh,
um deren theoretische Unsicherheiten zu reduzieren. Dann wird das Potenzial fĂŒr die
EinschrÀnkung der trilinearen Higgs-Selbstkopplung aus Einzel-Higgs-Raten erneut
untersucht, indem ebenso schwach eingeschrÀnkte Vier-Schwer-Quark-Operatoren
einbezogen werden, die bei der nÀchsthöheren Ordnung in die Einzel-Higgs-Raten
eingehen. Diese Operatoren korrelieren in hohem MaĂe mit der trilinearen Selbstkopplung,
was sich auf die Anpassungen auswirkt, die fĂŒr diese Kopplung anhand
von Einzel-Higgs-Daten vorgenommen wurden.
Der dritte Teil konzentriert sich auf die Higgs-Paarproduktion, einen wesentlichen
Prozess zur Messung der Higgs-Selbstkopplung, und setzt eine multivariate Analyse
ein, um ihr Potenzial zur Untersuchung der leichten Yukawa-Kopplungen zu untersuchen;
dadurch wird die Empfindlichkeit der Higgs-Paarproduktion fĂŒr die leichten
Quark-Yukawa-Wechselwirkungen erforscht.
SchlieĂlich werden im vierten Teil einige Modelle vorgestellt, die darauf abzielen, die
jĂŒngsten Flavour-Anomalien im Lichte einer globalen SMEFT-Bayesian-Analyse zu
erklÀren, die Flavour- und elektroschwache PrÀzisionsmessungen kombiniert.This thesis investigates some future aspects of Higgs measurements a decade after
its discovery, focusing on the potential for future runs of the Large Hadron Collider
(LHC). In particular, it aims to probe challenging couplings of the Higgs like
its self-coupling and interaction with light quarks.
The first part provides an overview of Higgs physics within the Standard Model
Effective Field theory (SMEFT). The second part is about single-Higgs production,
starting with a two-loop calculation of the gluon fusion component of Zh to reduce
its theoretical uncertainties. Then, the potential for constraining the Higgs trilinear
self-coupling from single Higgs rates is revisited; by including equally weaklyconstrained
four-heavy-quark operators entering at the next-to-leading order in single
Higgs rates. These operators highly correlate with the trilinear self-coupling,
thus affecting the fits made on this coupling from single Higgs data.
The third part focuses on the Higgs pair production, an essential process for measuring
Higgs-self coupling, employing multivariate analysis to study its potential
for probing light Yukawa couplings; thereby exploring the sensitivity of Higgs pair
production for the light-quark Yukawa interactions.
Finally, the fourth part showcases some models aiming to explain the recent flavour
anomalies in the light of a global SMEFT Bayesian analysis combining flavour and
electroweak precision measurements
Probing Higgs couplings to light quarks via Higgs pair production
We consider the potential of the Higgs boson pair production process to probe the light quark Yukawa couplings. We show within an effective theory description that the prospects of constraining enhanced first generation light quark Yukawa couplings in Higgs pair production are similar to other methods and channels, due to a coupling of two Higgs bosons to two fermions. Higgs pair production can hence also probe if the Higgs sector couples non-linearly to the light quark generations. For the second generation, we show that by employing charm tagging for the Higgs boson pair decaying to cc¯γγ, we can obtain similarly good prospects for measuring the charm Yukawa coupling as in other direct probes
Virtual corrections to via a transverse momentum expansion
We compute the next-to-leading virtual QCD corrections to the partonic cross
section of the production of a Higgs boson in association with a boson in
gluon fusion. The calculation is based on the recently introduced method of
evaluating the amplitude via an expansion in terms of a small transverse
momentum. We generalize the method to the case of different masses in the final
state and of a process not symmetric in the forward-backward direction
exchange. Our analytic approach gives a very good approximation (better than
percent) of the partonic cross section in the center of mass energy region up
to , where at the LHC of the total
hadronic cross section is concentrated.Comment: 21 pages, 3 Figures and 1 Tabl
B anomalies under the lens of electroweak precision
The measurements carried out at LEP and SLC projected us into the precision era of electroweak physics. This has also been relevant in the theoretical interpretation of LHCb and Belle measurements of rare B semileptonic decays, paving the road for new physics with the inference of lepton universality violation in RK( 17) ratios. The simplest explanation of these flavour anomalies \u2014 sizeable one-loop contributions respecting Minimal Flavour Violation \u2014 is currently disfavoured by electroweak precision data. In this work, we discuss how to completely relieve the present tension between electroweak constraints and one-loop minimal flavour violating solutions to RK( 17). We determine the correlations in the Standard Model Effective Field Theory that highlight the existence of such a possibility. Then, we consider minimal extensions of the Standard Model where our effective-field-theory picture can be realized. We discuss how these solutions to b \u2192 s\u2113\u2113 anomalies, respecting electroweak precision and without any new source of flavour violation, may point to the existence of a Z\u2032 boson at around the TeV scale, within the discovery potential of LHC, or to leptoquark scenarios
ER = EPR and non-perturbative action integrals for quantum gravity
International audienceIn this paper, we construct and calculate non-perturbative path integrals in a multiply-connected spacetime. This is done by summing over homotopy classes of paths. The topology of the spacetime is defined by EinsteinâRosen bridges (ERB) forming from the entanglement of quantum foam described by virtual black holes. As these âbubblesâ are entangled, they are connected by Planckian ERBs because of the ER = EPR conjecture. Hence, the spacetime will possess a large first Betti number B1. For any compact 2-surface in the spacetime, the topology (in particular the homotopy) of that surface is non-trivial due to the large number of Planckian ERBs that define homotopy through this surface. The quantization of spacetime with this topology â along with the proper choice of the 2-surfaces â is conjectured to allow non-perturbative path integrals of quantum gravity theory over the spacetime manifold
Higgs probes of top quark contact interactions and their interplay with the Higgs self-coupling
We would like to thank Ayan Paul for providing functions used in [78] that facilitated making some of the plots shown in this paper. L.A. thanks the computing resources provided by DESY and the INFN, Sezione di Padova, for hospitality during the final stage of this work. R.G. would like to thank Pier Paolo Giardino, Ken Mimasu, Paride Paradisi and Eleni Vryonidou for interesting discussions on C ~ and the four-fermion operators considered. L.A.'s research is supported by the Deutsche Forschungsgemeinschaft (DFG) Projektnummer 417533893/GRK2575 "Rethinking Quantum Field Theory". The work of J.B. has been supported by the FEDER/Junta de Andalucia project grant P18-FRJ-3735.We calculate the dominant contributions of third generation four-quark operators
to single-Higgs production and decay. They enter via loop corrections to Higgs decays
into gluons, photons and bb, and in Higgs production via gluon fusion and in association
with top quark pairs. We show that these loop effects can, in some cases, lead to better
constraints than those from fits to top quark data. Finally, we investigate whether these
four-fermion operators can spoil the determination of the trilinear Higgs self-coupling from
fits to single-Higgs data.German Research Foundation (DFG) 417533893/GRK2575FEDER/Junta de Andalucia P18-FRJ-373
Quantum no-singularity theorem from geometric flows
International audienceIn this paper, we analyze the classical geometric flow as a dynamical system. We obtain an action for this system, such that its equation of motion is the Raychaudhuri equation. This action will be used to quantize this system. As the Raychaudhuri equation is the basis for deriving the singularity theorems, we will be able to understand the effects and such a quantization will have on the classical singularity theorems. Thus, quantizing the geometric flow, we can demonstrate that a quantum spaceâtime is complete (nonsingular). This is because the existence of a conjugate point is a necessary condition for the occurrence of singularities, and we will be able to demonstrate that such conjugate points cannot occur due to such quantum effects