Constraints on the quartic Higgs self-coupling from double-Higgs production at future hadron colliders

We study the indirect constraints on the quartic Higgs self-coupling that arise from double-Higgs production at future hadron colliders. To this purpose, we calculate the two-loop contributions to the $gg \to hh$ amplitudes that involve a modified $h^4$ vertex. Based on our results, we estimate the reach of a $pp$ collider operating at $27 \, {\rm TeV}$ and $100 \, {\rm TeV}$ centre-of-mass energy in constraining the cubic and quartic Higgs self-couplings by measurements of double-Higgs and triple-Higgs production in gluon-fusion.Comment: Final version, to be published in JHE

Higgs decay into massive b-quarks at NNLO QCD in the nested soft-collinear subtraction scheme

We present a fully differential description of a decay of a scalar Higgs boson into massive b-quarks valid at next-to-next-to-leading order (NNLO) in perturbative quan- tum chromodynamics (QCD). We work within the nested soft-collinear subtraction scheme extended to accommodate massive partons. We include the loop-induced contribution in- volving a Higgs coupling to a top quark. We test our calculation against results existing in the literature, comparing the predictions for the total decay width and jet rates

NNLOPS description of the H→ bb‾\overline{b} decay with MiNLO

We present an event generator that describes the Higgs boson decay into b-quarks at next-to-next-to-leading-order (NNLO) in QCD and allows for a consistent matching to parton shower. For this purpose, we work within the POWHEG framework and employ the MiNLO method to produce an NNLO-accurate H →b$\overline{b}$ event sample which can further be interfaced with a generic Higgs boson production mode. The resulting events, that combine Higgs production and decay, can be matched to parton shower by means of a vetoed shower. As an example, we present a short phenomenological study for associated Higgs production (HZ) and vector boson fusion (VBF) processes. We release the source code that was used to obtain these results as an h_bbg user process in POWHEG-BOX-V$_{2}$. We also provide tools that enable interfacing the decay events with events for an arbitrary Higgs production mode and subsequent matching of the combined Les Houches (LH) events with a parton shower

Constraints on the quartic Higgs self-coupling from double-Higgs production at future hadron colliders

We study the indirect constraints on the quartic Higgs self-coupling that arise from double-Higgs production at future hadron colliders. To this purpose, we calculate the two-loop contributions to the gg → hh amplitudes that involve a modified h4 vertex. Based on our results, we estimate the reach of a pp collider operating at 27 TeV and 100 TeV centre-of-mass energy in constraining the cubic and quartic Higgs self-couplings by measurements of double-Higgs and triple-Higgs production in gluon-fusion

Anomalous couplings in associated VHVH production with Higgs decay to massive bb quarks at NNLO in QCD

We combine the NNLO QCD description of Higgs boson production in association with an electroweak vector boson $V = W~{\rm or}~Z$ with a similarly-precise description of Higgs boson decays into a pair of massive $b$ quarks and with the anomalous couplings that modify interactions of the Higgs and electroweak vector bosons. The resulting numerical code provides the most advanced theoretical tool to investigate such anomalous couplings in the associated Higgs boson production process. We study the impact of anomalous couplings on fiducial cross sections and differential distributions and argue that, with increased QCD precision, smaller anomalous couplings become accessible in kinematic regions where the effects of higher-dimensional operators in the Standard Model Effective Field Theory remain small and the EFT expansion is under control.Comment: 28 pages, 8 figure

A quest for precision: theory and phenomenology of strong interactions at hadron colliders

This thesis considers recent advances in applications of perturbative Quantum Chromodynamics (pQCD) to hadron collider physics, especially the LHC. In the main part it focuses on combining fixed-order predictions with all-order methods such as resummation and parton showers. After a general introduction to the realm of pQCD we consider a take on the resummation technique in momentum space to provide results for colour singlet production processes for distributions of transverse inclusive observables that vanish away from the Sudakov region. We work at (next-to-)3-leading-logarithmic (N3LL) accuracy and match our results to the (next-to-)2-leading order (NNLO) calculations. We present results for distributions of the transverse momentum of the Higgs boson as well as the transverse momentum of the Z boson and phi-star in the Drell-Yan production process. In the second part we discuss matching of the NNLO accurate calculations to parton showers using the MiNLO technique. The results are obtained by reweighting a sample of hard events at the partonic level with a K-factor that is fully differential in the Born phase space of the considered process. We treat the case of associated Higgs production (VH). We provide validation of our results and a short phenomenological study. In case of the HZ production we have considered the Higgs boson decay into a pair of b-quarks at the next-to-leading (NLO) order in QCD. Similarly we provide a phenomenological overview. In the last part we examine a constraint on the Higgs boson self-coupling that may be obtained in the HL-LHC programme. We work in the framework of Standard Model Effective Field Theory (SM EFT) and consider loop-induced effects of one additional dimension-six operator that modifies the SM Higgs sector.</p

Oddziaływania ładunków kolorowych w holograficznych modelach AdS/QCD

W niniejszej pracy rozważamy pewne aspekty teorii cechowania w fizyce teoretycznej, w kontekście oddziaływań silnych. Jesteśmy zainteresowani badaniem zjawiska uwięzienia koloru poprzez użycie modeli holograficznych. W celu znalezienia potencjału kwark - anty-kwark oraz flux-tub (wartość oczekiwana operatora gęstości akcji) pomiędzy nimi, używamy sposobu opartego o pętle Wilsona uogólnione na przypadek dualności teoria cechowania/teoria grawitacji. Rozważamy dwa modele holograficzne - czystą (niezmodyfikowaną) czasoprzestrzeń AdS5 oraz czasoprzestrzeń AdS5 z wbudowaną barierą. Wyliczamy funkcję Greena dla pola skalarnego w obu przypadkach (odpowiednio analitycznie i numerycznie), która jest niezbędna do badania flux-tub. Przypadek czystego AdS5 nie zadaje liniowego potencjału charakterystycznego dla uwięzienia, w przeciwieńst-wie do modelu AdS5 z barierą. Dalej badamy profile flux-tub, zachowanie asymptotyczne oraz prawa skalowania dla szerokości połówkowej oraz wartości maksymalnej przekroju poprzecznego flux-tuby.In this work we discuss the concept of gauge theories in theoretical physics in context of strong interactions. We are interested in examining of color confinement phenomenon by the use of holographic methods. In order to study quark - anti-quark potential and flux-tubes (action density) between them, we use the Wilson loop approach generalized for the case of gauge/gravity dualities. We consider two holographic models - pure AdS5 space-time and AdS5 hard-wall model. We find Green’s function for scalar field in both cases (analytically and numerically respectively), which is essential for the purpose of investigation of flux-tubes. Pure AdS5 does not provide linear potential characteristic for confinement, on the contrary to AdS5 hard-wall model. Further we find flux-tube profiles, asymptotic behavior and scaling laws of half-width and peak value of flux-tube cross-section