An important aspect of the Higgs boson physics programme at the LHC is to determine all the properties of this particle, including its mass, which is a free parameter in the SM, and its width. This presentation will discuss the latest developments in measurements of the Higgs boson mass and width, with data collected by the CMS experiment at a centre of mass energy of 13 TeV. Both direct and...
Precision studies of the properties of the Higgs and gauge bosons may provide a unique window for the discovery of new physics at the LHC. New phenomena can in particular be revealed in the search for lepton-flavor-violating or exotic decays of the Higgs bosons, as well as in their possible couplings to hidden-sector states that do not interact under Standard Model gauge transformations. This...
The total width of the Higgs boson is an important parameter for Higgs sector phenomenology. It is too small to be measured directly at the LHC, but indirect measurements can be performed using the off-shell Higgs boson production process in the ZZ and WW final states, as well as through interference effects in the diphoton decay channel. This talk presents the most recent indirect width...
The Higgs boson decay to two vector bosons can be used to perform some of the most precise measurements of the Higgs boson production cross sections. This talk presents the more recent Higgs boson cross section measurements by the ATLAS experiment in the W boson decay channel. Interpretations of these results in the context of Standard Model effective field theories will be presented. The...
Searches for axion-like-particles (ALPs) in Higgs boson decays, as well as searches for ALP production with two top quarks are presented, using LHC collision data at 13 TeV collected by the ATLAS experiment in Run 2. The searches cover a mass range of ALPs below the Z-boson mass. Novel reconstruction and identification techniques used in these searches are described.
We present searches for rare and beyond-the-standard-model decays of the Higgs boson with the CMS detector using the full run 2 dataset. Amongst others, Higgs boson decays to two (pseudo-) scalars and to invisible particles are discussed.
We will discuss the latest differential measurements of Higgs boson cross sections with the CMS detector in bosonic decay channels. Both fiducial differential cross section measurements and measurements in the simplified template cross section framework will be presented. The data collected during Run 2 of the LHC by the CMS experiment are used. We also present interpretations of these...
We present searches for a resonance production in the diphoton final state with a mass lower than 125 GeV, predicted by several theoretical models beyond the standard one, as for example axion-like particles. Different possible production modes at the LHC are investigated.
We present new calculations of the leading-order one-loop amplitude and the decay rate for $H\to \nu \bar{\nu} \gamma$ within the Standard Model. We present the full reduction of the Amplitude to a set of basic Passarino-Veltman functions resulting in more concise expressions compared to prior works. In this work we obtained the total decay rate as $\Gamma(H\to \nu\bar{\nu}...
The newest Higgs combined measurements at CMS are presented in this talk.
The discovery of the Higgs boson with the mass of about 125 GeV completed the particle content predicted by the Standard Model. Even though this model is well established and consistent with many measurements, it is not capable to solely explain some observations. Many extensions of the Standard Model addressing such shortcomings introduce additional neutral Higgs-like bosons. The current...
Very detailed measurements of Higgs boson coupling and kinematical properties can be performed using the data collected with the ATLAS experiment, exploiting a variety of final states and production modes, and probing different regions of the phase space with increasing precision. These measurements can then be combined to exploit the specific strength of each channel, thus providing the most...
In the Standard Model, one doublet of complex scalar fields is the minimal content of the Higgs sector in order to achieve spontaneous electroweak symmetry breaking. However, several theories beyond the Standard Model predict a non-minimal Higgs sector and introduce charged scalar fields that do not exist in the Standard Model. As a result, singly- and doubly-charged Higgs bosons would be a...
We present results for the Higgs production cross section in the gluon-gluon-fusion channel at next-to-next-to-leading order with finite quark masses. While the impact of finite quark masses are power-suppressed, the precision of state-of-the-art theory predictions makes an exact determination of this effect indispensable. With this result, we address one of the leading theory uncertainties of...
Supersymmetry (SUSY) provides elegant solutions to several problems in the Standard Model, and searches for SUSY particles are an important component of the LHC physics program. This talk will present the latest results from SUSY searches from ATLAS, where Higgs bosons are produced as part of the decay chain of supersymmetric particles. A variety of models and possible final states are...
We present searches for additional neutral and charged Higgs boson with the CMS detector using the full run 2 dataset. The presented searches also include decays of heavy Higgs bosons into other Higgs bosons (both the 125 GeV Higgs boson and other additional Higgs bosons).
Recent analyses on high-energy inclusive Higgs-boson rates in proton collisions, matched with the state of-the-art fixed-order N$^3$LO accuracy, have shown that the impact of high-energy resummation corrections reaches 10% at the FCC nominal energies. This supports the statement that electroweak physics at 100 TeV is expected to receive relevant contributions from small-$x$ physics. In this...
The Future Circular Collider stands at the forefront of the European Strategy for Particle Physics vision. A technical and financial feasibility study for the 100 km infrastructure is currently underway. A main objective of the FCC is to comprehensively explore the properties of the Higgs boson in e+e- collisions. The FCC-ee makes use of the well-known centre-of-mass energy by using Z tagging...
We revisit the stability of the Standard Model vacuum, and investigate its quantum effective potential using the highest available precision in theory tools and experimental input parameters to date. We observe that the stability of the electroweak vacuum centrally depends on the values of the top mass and the strong coupling constant and how their uncertainties impact SM vacuum stability. We...
The measurement of the production of Higgs boson pairs (HH) at the LHC allows the exploration of the Higgs boson interaction with itself and is thus a fundamental test of the Standard Model theory and has a key role in the determination of the Higgs boson nature. The most recent results from the CMS collaboration on measurements of non-resonant HH production using different final states and...
Precise determination of Higgs parameters is crucial for validation of the Standard Model or any alternative BSM theory addressing open questions either in particle physics or cosmology. Clean environment, high precision of measurements dominated by the statistical uncertainty and a possibility of beam polarization can provide per mile level precision of the Higgs couplings measurements as...
The Future Circular Collider stands at the forefront of the European Strategy for Particle Physics vision. Currently, a technical and financial feasibility study for the 100 km infrastructure is underway. The physics programme is based on the sequence of a 90-365 GeV high luminosity and high precision e+e- collider, FCC-ee, followed by a 100 TeV hadron collider, FCC-hh. A main objective of the...
In the Standard Model, the ground state of the Higgs field is not found at zero but instead corresponds to one of the degenerate solutions minimising the Higgs potential. In turn, this spontaneous electroweak symmetry breaking provides a mechanism for the mass generation of nearly all fundamental particles. The Standard Model makes a definite prediction for the Higgs boson self-coupling and...
Muon collisions at multi-TeV center-of-mass energies provide an ideal environment for studying Higgs boson properties. At these energies, the high production rates and low background contributions allow for precise measurements of Higgs couplings to fermions and bosons. This contribution aims to provide an overview of the results obtained at a center-of-mass energy of 3 TeV, as well as...
The virtual corrections for $gg \to HH$ at NLO QCD have been efficiently approximated using a Taylor expansion in the limit of a forward kinematics. The same method has been recently applied to the calculation of a subset of the NNLO corrections, which are desirable given the significant impact, at NLO, of the uncertainty due to the choice of the top mass renormalization scheme. In this talk,...
The FCC-ee offers powerful opportunities to determine the Higgs boson parameters, exploiting about 2*10^6 e+e-→ZH events and almost 10^5 WW→H events at centre-of-mass energies around 240 and 365 GeV. The determination of the Higgs boson mass with a precision significantly better than the Higgs boson width (4.1 MeV in the Standard Model) is a prerequisite to either constrain or measure the...
Higgs pair production from gluon fusion is a process of high interest for the upcoming HL-LHC phase. In this talk we present our calculation of electro-weak NLO contributions comprising Yukawa-type and Higgs self-coupling corrections at two-loop level. Also, we show the effect of these corrections on the Higgs pair's invariant mass distribution.
We systematically study potential effects of BSM physics in the e+ e- -> Z H process. To this end, we include all relevant dimension-6 Standard Model Effective Field Theory operators and work to next-to-leading order (NLO) accuracy in the electro-weak coupling. We consider both polarized and unpolarized electron and positron beams and present results for $\sqrt{s}=240, 365 and 500~GeV and...
Several physics scenarios beyond the Standard Model predict the existence of new particles that can subsequently decay into a pair of Higgs bosons. This talk summarises ATLAS searches for resonant HH production with LHC Run 2 data. Several final states are considered, arising from various combinations of Higgs boson decays.
With the current precision of measurements by ATLAS and CMS experiments, it cannot be excluded that a SM-like Higgs boson is a CP violating mixture of CP-even and CP-odd states. We explore this possibility here, assuming Higgs boson production in ZZ-fusion, at 1 TeV ILC, with unpolarized beams. The full reconstruction of SM background and fast reconstruction of the signal is performed,...
In this talk I will present the most recent CMS searches for heavy resonances decaying to HH and SH pairs. The S particle can be a standard model vector boson (W or Z) or a new scalar particle (Y) predicted in BSM models. Results from combination of different final states will be also shown.
In this talk, I will present an investigation into finite width and interference effects in di-Higgs production at the LHC, with a particular focus on the real Higgs singlet extension of the Standard Model. This extension enhances di-Higgs production through the resonant decays of an additional heavy scalar into two SM-like Higgs bosons. The study examines the impact of interference between...
We study a CP-violating top Yukawa coupling at muon collider through $\mu^-\mu^+\to t\bar{t}h\nu\bar{\nu}$ process. The gauge invariant Lagrangian is obtained by a dimension-6 operator. Although the cross section and distributions are gauge invariant, amplitudes calculated in the Feynman Diagram (FD) gauge allow us to understand the origin of the energy and angular dependence of CP violating...
The European Strategy for Particle Physics identifies an e+e- Higgs factory as its top priority and the first step towards an ultra-high energy future hadron collider. The Future Circular Collider (FCC) is being proposed at CERN to address these goals. The FCC includes an electron-positron collider (FCC-ee), which will be followed by an energy-frontier hadron collider (FCC-hh).
New long...
In searches for beyond the Standard Model (BSM) Physics, bottom-up effective field theories (EFTs) such as the Standard Model EFT (SMEFT) and Higgs EFT (HEFT) have become crucial theoretical tools. Besides specifying their particle content and the respective symmetries on which the higher-dimensional operators are built, the choice of a power counting in a small parameter is the third...
The Higgs portal to BSM is very well motivated both theoretically and experimentally. We study long-lived BSM particles in the Higgs portal model, produced either from the decay of a B-meson or the Higgs boson. We discuss the search for these particles at future colliders, like the 100 TeV future collider experiment. Given the need to optimise the designs of dedicated LLP detectors for future...
Various extensions of the Standard Model predict the existence of additional Higgs bosons. If these additional Higgs bosons are sufficiently heavy, an important search channel is the di-top final state. In this channel, interference contributions between the signal and the corresponding QCD background process are expected to be important. If more than one heavy scalar is present, besides the...
Testing the Yukawa couplings of the Higgs boson with fermions is essential to understanding the origin of fermion masses. Higgs boson decays to quark pairs are an important probe of these couplings, and of properties of the Higgs boson more generally. This talk presents various measurements of Higgs boson decays into two bottom quarks as well as searches for Higgs boson decays into two charm...
Statistically significant excesses exist at around $152$ GeV in associated di-photon production contained in the sidebands of SM Higgs analyses. They are most pronounced in the $\gamma \gamma + \tau$, $\gamma \gamma + \text{MET}$, $\gamma \gamma + \geq 1 \ell +\geq 1b$, $\gamma \gamma + 4 j$ signal regions, and can be explained by the Drell-Yan production of new Higgs bosons, i.e. $p p \to W...
e will discuss the latest differential measurements of Higgs boson cross sections with the CMS detector in fermionic decay channels and ttH production. Both fiducial differential cross section measurements and measurements in the simplified template cross section framework will be presented. The data collected during Run 2 of the LHC by the CMS experiment are used. We also present...
The discovery of the Higgs boson ten years ago and successful measurement of the Higgs boson couplings to third generation fermions by ATLAS and CMS mark great milestones for HEP. The much weaker coupling to the second generation quarks predicted by the SM makes the measurement of the Higgs-charm coupling much more challenging. With the full run-2 data collected by the CMS experiment, a lot of...
Recently, statistically significant excesses in inclusive and associated di-photon searches have been observed at the LHC, accumulating at around $95$ GeV and $152$ GeV, respectively. In this context, I will argue how the most general CP-violating 2HDM in the Yukawa alignment limit can account for these observations. In the Higgs basis, where the two scalar doublets are identified as $H_1$ and...
We explore the possibility of CP-violation in the complex-singlet extension of 2HDM. The addition of complex singlet paves the way for additional sources of CP-violation compared to 2HDM. If a Z2-symmetry is imposed on the complex-singlet, it can accommodate a dark matter candidate as well. We identify the regions of parameter space, that can fit DM observables and at the same time generate...
The b-quark Yukawa coupling $y_b$ can be measured in $H\to b\bar{b}$ decay. While $H\to b\bar{b}$ is the main decay mode of the Higgs boson, measuring it experimentally is challenging because of the large number of b-quarks from other QCD processes. However, Higgs boson production in weak-boson fusion (WBF) can be distinguished from those QCD backgrounds by the presence of two nearly...
The full set of data collected by CMS experiment at a centre of mass energy of 13 TeV allows searches for rare production modes of the Higgs boson, subdominant with respect the ones already observed at the LHC, by using a variety of decay modes profiting of the ones with largest expected branching fractions. They include associate production of the Higgs with two b-quarks, with a c-quark, or...
Minimal triplet scalar extension of the Standard Model demanding custodial symmetry gives rise to a new model, the extended Georgi-Machacek (eGM) model, not the well-known Georgi-Machacek (GM) model. In this talk, I will discuss the theoretical bounds on the model parameter space, such as next-to-leading order unitarity and state-of-the-art bounded from below conditions on the potential...
Since the discovery of the Higgs boson in 2012, Higgs physics has entered the precision era, with a key focus on measuring the Yukawa interactions between the Higgs boson and Standard Model fermions. The LHC serves as a crucial Higgs factory, and the High Luminosity LHC (HL-LHC) is expected to provide even more precise measurements due to its increased luminosity. However, effective charm and...
While the third-generation couplings of the Higgs boson have been observed and studied, the first and second-generation fermion couplings to the Higgs (except the Higgs-muon coupling) remain elusive. This is due to two reasons mostly: light quark Yukawas smallness, and the difficulty of tagging light quarks efficiently. Therefore, even at the High Luminosity LHC (HL- LHC), the projections for...
To fully characterize the Higgs boson, it is important to establish whether it presents coupling properties that are not expected in the Standard Model of particle physics. These can probe BSM effects, such as CP conserving or CP violating couplings to particles with masses not directly accessible at the LHC through virtual quantum loops. In this talk we will present the most recent searches...
Detailed measurements of Higgs boson properties can be performed using its decays into fermions, providing in particular a key window into the nature of the Yukawa interactions. This talk presents the latest measurements by the ATLAS experiment of Higgs boson properties in its delays into pairs of leptons, using the full Run 2 pp collision dataset collected at 13 TeV.
Effective Field Theories provide an interesting way to parameterize indirect BSM physics, when its characteristic scale is larger than the one directly accessible at the LHC, for a large class of models. Even if the Higgs boson is SM-like, BSM effects can manifest itself through higher-dimension effective interactions between SM fields, providing indirect sensitivity through distortions of...
We present progress on the calculation of the virtual NNLO corrections to $t\bar{t}H$ production in the $q\bar{q}$-channel. We focus on the numerical evaluation of the amplitude, and the associated challenge of constructing a grid to interpolate the amplitude over a 5-dimensional phase space.
We present calculations of higher-order corrections for the production of a heavy charged-Higgs pair ($H^+H^−$) in the two-Higgs-doublet model at LHC energies. We calculate the NNLO soft-plus-virtual QCD corrections and the N$^3$LO soft-gluon corrections to the total cross section and the charged-Higgs rapidity distribution.
The study of Higgs boson production in association with one or two top quarks provides a key window into the properties of the two heaviest fundamental particles in the Standard Model, and in particular into their couplings. This talk presents property measurement of Higgs boson, in particular cross section and CP nature, with tH and ttH production in pp collisions collected at 13 TeV with the...
Despite the discovery of the Higgs boson, the Higgs sector of the standard model is still not fully established. In particular, the self-couplings of the Higgs boson, and its couplings with gauge bosons, are still to be fully determined. We consider electroweak corrections to the process $H\rightarrow 4l$. The corrections depend on the HHH and ZZHH couplings. We investigate this dependence in...
The large dataset of about 3 ab-1 that will be collected at the High Luminosity LHC (HL-LHC) will be used to measure Higgs boson processes in detail. Studies based on current analyses have been carried out to understand the expected precision and limitations of these measurements. The large dataset will also allow for better sensitivity to di-Higgs processes and the Higgs boson self coupling....
We present NLO QCD results for Higgs boson production in association with one jet, including anomalous Higgs-top and Higgs-gluon couplings and with full top quark mass dependence. We will compare the full theory with varied anomalous couplings to the Standard Model, based on our implementation into POWHEG-BOX-V2. Of special interest will be the $p_{T,H}$ distribution, since the high-pT tail...
Single- and di-Higgs prospects for CMS at HL-LHC are presented in this talk.
The Higgs decay into four leptons remains one of the best measured decay modes of the Higgs at the LHC, making precision calculations necessary for accurate predictions and constraints. We present the first calculation of the decay width for H to llZ at full one-loop in the Standard Model Effective Field Theory. At one-loop, a variety of new coefficients appear that modify the total rate and...
Measuring the Higgs self-coupling is a key target for future colliders, in particular through di-Higgs production at e+e- Linear Colliders with GeV, e.g. at ILC, C3 or CLIC. This contribution will discuss the roles and the interplay of di-Higgs production processes at various collider energies, including the case of non-SM values of the self-coupling. Previous studies, already based on...
The determination of the double and triple Higgs production cross sections will allow probing the triple and quartic self-couplings of the Higgs boson, providing an opportunity to directly explore the nature of the scalar potential. The multi-TeV muon collider offers a unique opportunity to measure these couplings, thanks to the high production cross sections of multi-Higgs processes and the...
We study the impact of RGE running and mixing of SMEFT operators on differential observables in $Hj$, $t \bar{t} H$ and $HH$ production at the LHC. We focus on a subset of operators closed under the QCD-induced anomalous dimension matrix and explore the impact of employing a fixed or dynamical scale on the EFT predictions for the Higgs transverse momentum and Higgs pair invariant mass spectra....
We study the capabilities of a muon collider, at 3 and 10 TeV center-of-mass energy, of probing the interactions of the Higgs boson with the muon. We consider all the possible processes involving the direct production of EW bosons ($W$, $Z$, and $H$) with up to five particles in the final state. We study these processes in the HEFT and SMEFT frameworks, assuming that the dominant BSM effects...
Geometric formulations of scalar EFTs formulate fields as coordinates on a field space manifold, which provides an alternative method of studying theories by relating physical quantities emerging from the two derivative term to geometric tensors which are invariant under field redefinitions.
Fibre bundles provide us with the tools to extend the formalism to both describe the potential via...
The $\mathcal{CP}$ structure of the Higgs couplings is a fundamental property which has not yet been constrained with high precision. The Higgs-top quark coupling is of particular interest due to its size and accessibility at the LHC via top-associated Higgs production and gluon fusion. To improve the sensitivity to the CP property of this coupling, we propose an extension to the STXS...
We explore how quantum gravity effects, manifested through the breaking of discrete symmetry responsible for both Dark Matter and Domain Walls, can have observational effects through CMB observations and gravitational waves. To illustrate the idea we consider a simple model with two scalar fields and two Z2 symmetries, one being responsible for Dark Matter stability, and the other...
We study the single top plus Higgs production process at the LHC with a CP violating Yukawa coupling from a dimension-6 operator. The amplitude of the subprocess ub>dtH is obtained both in the Unitary (U) and Feynman-Diagram (FD) gauges. Energy and angular distributions of the cross section and CP violating asymmetries are understood clearly from the interference among the FD gauge amplitudes.
The recent adoption of the LISA mission by the European Space Agency marks a significant milestone for gravitational wave cosmology, offering unprecedented sensitivity to gravitational wave backgrounds emitted at temperatures around a few hundred GeV. Intriguingly, this temperature range not only corresponds to the electroweak epoch but also coincides with the scale at which the freeze-out of...
