Due to the inclination for forward gauge radiation, lepton colliders beyond a few TeV are effectively electroweak boson colliders, suggesting the treatment of electroweak bosons as constituents of high-energy leptons. In this talk, we summarize the status of electroweak boson parton distribution functions, present new theoretical progress on their implementation, and give a brief outlook for...
It has been known since the 1950's that an unstable particle is associated with a complex pole in the propagator. This had to be rediscovered twice: in the early 1970's in the context of hadronic resonances, and in the early 1990's in the context of the $Z$ boson. The physical mass of the particle is the real part of the pole in the complex energy plane. In hadronic physics, this replaced the...
We investigate dark gauge-mediated supersymmetry breaking with an unbroken $U(1)_D$ symmetry and a massless dark photon. Messengers charged under both Standard Model and dark gauge groups generate new soft SUSY-breaking terms via gauge kinetic mixing. Large mixing significantly alters superpartner spectra compared to standard GMSB, reduces the ฮผ parameter, and predicts a relatively light...
The anomalous magnetic moment of the muon, i.e. ($g-2$), is one of the versatile and promising probes of new physics at the GeV scale, particularly for $Z^{\prime}$ gauge bosons that couple to both leptons and quarks. Due to inputs from experiments, lattice QCD as well as theory collaborations, one can constrain such BSM theories using various combinations of these inputs. Based on this idea,...
The electron and muon anomalous magnetic moment (gโ2) are among the most precisely tested quantities in nature. But what about tau-leptons? Long overlooked, tau gโ2 is so poorly constrained it cannot even test Schwinger's landmark $\alpha/2\pi \simeq 0.0012$ prediction from 1948. This leaves striking room for new physics where taus enjoy 280 times greater sensitivity than muons. Creative...
As the heaviest known fundamental particle, the top quark plays a pivotal role in the search for new physics. Many beyond-the-Standard-Model theories predict interactions between the top quark and yet undiscovered particles. With the LHC becoming a top quark factory, it offers unprecedented opportunities to study top quark properties and explore potential signs of new physics. In this talk,...
The high center-of-mass energy of proton-proton collisions and the large available datasets at the CERN Large Hadron Collider allow the study of rare processes of the Standard Model with unprecedented precision. Measurements of rare SM processes provide new tests of the SM predictions with the potential to unveil discrepancies with the SM predictions or provide important input for the...
The exceptionally large dataset collected by the ATLAS detector at the highest proton-proton collision energies provided by the LHC enables precision testing of theoretical predictions using an extensive sample of top quark events. Measurements of the inclusive top quark production rates at the LHC have reached a precision of several percent and test advanced Next-to-Next-to-Leading Order...
The top-quark mass is one of the key fundamental parameters of the Standard Model that must be determined experimentally. Its value has an important effect on many precision measurements and tests of the Standard Model. The Tevatron and LHC experiments have developed an extensive program to determine the top quark mass using a variety of methods. In this contribution, the top quark mass...
We present results from searches for resonances with enhanced couplings to third generation quarks, based on proton-proton collision data at a center-of-mass energy of 13 TeV recorded by CMS. The signatures include single and pair production of vector-like quarks and heavy resonances decaying to third-generation quarks. A wide range of final states, from multi-leptonic to entirely hadronic is...
A general two Higgs doublet model is adopted to study flavor changing neutral Higgs (FCNH) interactions in $pp \to t \phi\to t(tc)$ at the Large Hadron Collider, where $\phi$ is either the CP-even Higgs scalar ($H$) or the CP-odd Higgs pseudoscalar ($A$). We considered two final states, (i) single lepton: $ttc \to bjj cb\ell\nu$, and (ii) same sign di-lepton: $ttc \to bbc \ell\ell \nu\nu$...
Tensor Networks, originally developed for quantum many-body systems, offer powerful representations of high-dimensional data. When applied to discriminate top quark signals from QCD backgrounds, the entanglement entropy of the tensor network model can give us insight into the correlations it has learned. Moreover, our study shows tensor network model is more resilient to detector effects and pile-up.
The Standard Model of Particle Physics explains many natural phenomena yet remains incomplete. Many new physics models (such as leptoquarks, W'/Z', or heavy neutral leptons) could manifest in final states involving multiple leptons. This talk will summarise the latest results from ATLAS in searches involving final states with leptons.
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 of explaining some observations by itself. Many extensions of the Standard Model addressing such shortcomings introduce beyond-the-Standard-Model couplings to the Higgs...
This talk reports recent precision measurements of diboson production and the study of anomalous Gauge boson self couplings (and constraints on EFT wilson coefficients) in ATLAS. These results offer further insights into the structure of electroweak interactions and provide greater sensitivity to new physics effects with improved measurement precision.
Driven by the increasing interest in probing spin structure and quantum entanglement in diboson processes, we study polarization and spin correlations in Higgs โ VV decays. We show that higher-order electroweak corrections are crucial for accurately determining these coefficients and discuss their impact on proposed entanglement measurements.
The event rates and kinematics of Higgs boson production and decay processes at the LHC are sensitive probes of possible new phenomena beyond the Standard Model (BSM). This talk presents the most recent results in the measurements of Higgs boson production and decay rates, obtained using the full Run 2 and partial Run 3 pp collision dataset collected by the ATLAS experiment at 13 TeV and 13.6...
This talk reports recent differential measurements of single W boson in ATLAS for both on-shell and off-shell scenarios, which provide sensitive inputs to improve the constraints on PDFs and relevant EFT wilson coefficients.
The interpretation of multi-particle spin systems produced at colliders as quantum states has shown the potential to obtain quantum information at colliders. For instance, top quark or lepton pairs produced at colliders exhibit correlated spin states. Fermion pair production at lepton colliders presents an ideal source for comprehensive quantum tomography of the production process, enabling...
We discuss systematic limitations of entanglement measurements in particle production processes at collider experiments. Using the example of $pp\to ZZ$ production at the Large Hadron Collider, we study the distinct contributions that arise at leading and higher orders, which can affect the interpretation of the system as a two-qutrit $ZZ$ system.
This talk reports recent measurements of vector boson scattering and triboson processes in ATLAS. These results provide stringent tests of the Higgs mechanism, as well as the Gauge sector of the electroweak theory (through studying anomalous Gauge boson couplings), and offer a new avenue for precision tests of the SM as well as MC modelling. In addition, the investigation of boson...
We consider 2-to-2 scatterings of Higgs bosons in a CP-conserving two-Higgs-doublet model (2HDM) and study the implication of maximizing the entanglement in the flavor space, where the two doublets $\Phi_a$, $a=1,2$, can be viewed as a qubit: $\Phi_1=|0\rangle$ and $\Phi_2=|1\rangle$. More specifically, we compute the scattering amplitudes for $\Phi_a \Phi_b \to \Phi_c \Phi_d$ and require ...
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...
Though the Standard Model (SM) of particle physics has been a very successful theory in explaining a wide range of measurements, there are still many questions left unanswered such as incorporation of gravity into SM, neutrino masses, matter-antimatter asymmetry, supersymmetry, or existence of dark matter candidates. One of the possible solutions to address these challenges is the extension of...
Recent SMEFT studies emphasize the consistent inclusion of $\frac{1}{\Lambda^4}$ terms in SMEFT predictions. In this presentation, we explore SMEFT up to $\frac{1}{\Lambda^4}$, incorporating renormalization group evolution (RGE) effects from the running of SMEFT Wilson coefficients (WCs), including dimension-8 contributions. We discuss the current status of dimension-8 renormalization and...
We perform a model-independent analysis of the dimension-six terms that are generated in the low energy effective theory when a hidden sector that communicates with the Standard Model (SM) through a specific portal operator is integrated out. We work within the Standard Model Effective Field Theory (SMEFT) framework and consider the Higgs, neutrino and hypercharge portals. We find that, for...
This talk presents precise measurement of the CP properties of the Higgs boson using the full dataset collected in pp collisions at 13 TeV during Run 2 and at 13.6 TeV during Run 3 of the LHC. The measurements are performed in various Higgs boson production and decay modes, as well as their combinations. Observation of deviations between these measurements and Standard Model (SM) predictions...
Many theories beyond the Standard Model (SM) have been proposed to address several of the SM shortcomings. Some of these beyond-the-SM extensions predict new particles or interactions directly accessible at the LHC, but which would leave unconventional signatures in the ATLAS detector. These unconventional signatures require special techniques and reconstruction algorithms to be developed,...
The Belle and Belle II experiments have collected a 1.1 ab$^{-1}$ sample
of $e^+ e^-\to B\bar{B}$ collisions at a centre-of-mass energy
corresponding to the $\Upsilon(4S)$ resonance. These data, with low
particle multiplicity and constrained initial state kinematics, are an
ideal environment to search for rare electroweak penguin and radiative
$B$ decays. Results include those related to...
Many models beyond the standard model predict new particles with long lifetimes. These long-lived particles (LLPs) decay significantly displaced from their initial production vertex thus giving rise to non-conventional signatures in the detector. Dedicated triggers and innovative usage of the CMS detector are exploited in this context to significantly boost the sensitivity of such searches at...
This talk reviews recent measurements of multiboson production using CMS data at sqrt(s) = 13 and 13.6 TeV. Inclusive and differential cross-sections are measured using several kinematic observables.
The Belle and Belle II experiment have collected samples of $e^+e^-$
collision data at centre-of-mass energies near the $\Upsilon(nS)$
resonances. These data have constrained kinematics and low
multiplicity, which allow searches for dark sector particles in the mass
range from a few MeV to 10 GeV. Using a 426 fb$^{-1}$ sample collected
by Belle II, we search for inelastic dark matter...
We present a methodology to streamline implementation of massive-quark radiative contributions in calculations with a variable number of active partons in proton-proton collisions. The methodology introduces subtraction and residual heavy-quark parton distribution functions (PDFs) to implement calculations in the Aivazis-Collins-Olness-Tung (ACOT) factorization scheme and its simplified...
The addition of a heavy charged vector gauge boson $\mathrm{W}^\prime$ to the Standard Model (SM) with negligible quark couplings ("quarkophobic") and triple gauge couplings can address issues with the SM, such as the B-meson anomalies and recent discrepancies in the W boson mass measurements. Such a model featuring a large $\mathrm{W}^\prime$ decay width has not yet been explored at the LHC...
Since the discovery of the Higgs Boson at the Large Hadron Collider, much progress has been made in characterizing its couplings to the Electroweak bosons and the third generation of fermions. In this talk, I will discuss the LHC constraints in the leptonic sector of a flavor-violating 2HDM, a well-motivated model which is also constrained by precision measurements. I will also characterize...
