Theoretical physicists describe nature by i) building a theory model and ii) determining the model parameters. The latter step involves the dual aspect of both fitting to the existing experimental data and satisfying abstract criteria like beauty, naturalness, etc. We use the Yukawa quark sector as a toy example to demonstrate how both of those tasks can be accomplished with machine learning...
Model building in particle physics relies heavily on the intuition of theorists to select appropriate symmetry groups, particle content, and representation assignments. However, the space of viable models is vast. Exploring the space is usually computationally expensive. The challenge lies in the combinatorial complexity of symmetry and representation choices and the computational effort...
This talk reports recent measurements of jet production cross-sections and the sub-structure properties inside jets in ATLAS. These measurements provide important inputs to understand Quantum Chromodynamics at the high energy regime.
Studying heavy-flavour hadron properties provides a extensive tests for various QCD predictions as well as a means to probe the Standard Model validity. ATLAS experiment, being a general-purpose detector at LHC, is particularly successful in such measurements with final states involving muons, thanks to large collected integrated luminosity and precise muon reconstruction and triggering. This...
Signatures of new physics at the LHC are varied and, by nature, often very different from those of Standard Model processes. Novel experimental techniques, including dedicated data streams, are exploited to enhance the sensitivity of the CMS Experiment to search for such signatures. In this talk, we highlight the most recent CMS results, obtained using the data collected at the LHC Run-2 and...
The decays B->PP, where the pseudoscalar P is a pi or K, have been studied under the assumption of flavor SU(3) symmetry. The global fit reveals a 3.6 sigma discrepancy with the Standard Model. Separate fits for Delta S = 0 and Delta S = 1 decays find parameter sets that differ by a factor of 10, indicating a flavor SU(3) breaking of 1000%, significantly larger than the 20% breaking expected...
We present the first complete two-loop calculation of the electric dipole moment of the
electron, as well as the rates of the lepton-flavor violating decays μ → e + γ and τ → e/μ +
γ, in the unconstrained two-Higgs doublet model. We include the most general Yukawa
interactions of the Higgs doublets with the Standard Model fermions up to quadratic order,
and allow for generic phases in the...
Indirect CP violation in kaon decays is measured with a precision at the permil level. In this talk, I briefly review the status of the standard model prediction, including current efforts to calculate the four-loop QCD corrections using the MaRTIn code.
In this talk I will focus on the study of the leptonic $B\rightarrow \ell \nu$ decay at next-to-leading order in QED. The future improvements of experimental measurements of this channel require a reliable theory prediction, hence a careful theoretical estimate of QED corrections. The multi-scale character of this process requires an appropriate effective theory (EFT) construction to factorize...
TBA
Light exotics effective field theory (LEX-EFT) focuses on the idea that there may be light BSM particles that are so far undiscovered. This talk will focus on a specific portal to new physics, the quark-lepton portal. This portal encompasses all possible interactions, up to dimension six, that a quark, lepton, and LEX field (with or without additional SM fields) can have. Within this portal,...
The latest measurements of branching ratios, related to hadronic decays of B mesons to charm and pseudo-scalar final states (DP), showed disagreements with theoretical predictions based on QCD factorization. Meanwhile, SU(3) symmetry-breaking was found in recent studies to exceed the Standard Model threshold of 20% (in B decays to two pseudo-scalars). In the light of these results, an analysis...
The traditional quark model accounts for the existence of baryons, like protons and neutrons, which consist of three quarks, as well as mesons, composed of a quark and antiquark pair. Only recently has substantial evidence started to accumulate for exotic states composed of four or five quarks or antiquarks. In this study, the CMS Collaboration investigates the recently discovered family of...
Theoretical predictions for hadronic decays are extremely challenging due to the non-perturbative nature of QCD. The SU(3) approximate flavor symmetry of QCD can be used to derive relations between hadronic decay amplitudes. We perform a systematic study on how the SU(2) flavor symmetry amplitude sum rules can be used to give predictions for physical observables. In particular, we show a...
We show how the axion quality problem resulting from the violation of global symmetries by quantum gravity can be solved in presence of a gauged $U(1)_F$ flavor symmetry in a class of models. The gauged $U(1)_F$ explains the hierarchical structure of fermion masses and mixings via the Froggatt-Nielsen mechanism. The axion is realized as a byproduct of an accidental $U(1)$ symmetry with a QCD...
Light new particles could be emitted in nucleon decays if they have baryon-number-violating couplings. Even though they usually leave the detector as missing energy, interesting signatures can arise in such decays in underground detectors such as Super-Kamiokande and DUNE. In the particularly simple case of light sterile neutrinos, nucleon decays can even be an efficient production mechanism...
Baryon number violation is our most sensitive probe of physics beyond the Standard Model, conveniently encoded in higher-dimensional effective operators. Operators involving derivatives are usually ignored in phenomenological analyses since they are generically suppressed compared to non-derivative operators. We will study exceptions to this statement and explore scenarios in which derivative...
We propose an $E_6$ inspired Pati-Salam (PS) model that naturally accommodates multi-TeV leptoquark gauge bosons, X, with a softly broken discrete $Z_2$ symmetry. Standard Model (SM) fermions are $Z_2$-even in this framework, whereas exotic fermions are $ Z_2$-odd. An interesting feature of the model is that the PS gauge bosons are $Z_2$-odd, enabling them to couple exclusively between...
We introduce and investigate the effects of a light scalar interacting with the
short-lived kaon and the $K_S → μ^+μ^−$ decay. We use the results of searches performed at
kaon factories as well as the Standard Model predictions for this decay to constrain the
couplings of a ϕ particle with a mass $m_ϕ$ of the order of MeV. We also examine the time evolution of the kaon beams with the full...
More evidence of New Physics (NP) has been observed in charged current decays of $\bar{B} \to {D^*} \ell \bar{\nu}$, as measured by the BaBar, Belle, and LHCb experiments. Curiously, the observable $R_{D^*}$ has been found to exceed Standard Model (SM) expectations, with a combined significance of $3.4\sigma$. Moreover, there is further motivation for NP in the muon sector due to persistent...
Increasing attention has been given recently to the theory and phenomenology of portal matter (PM) models — a BSM framework in which the standard model (SM) local gauge symmetry group is augmented by a local dark group $U(1)_D$, of which the mediator is the dark photon, and kinetic mixing between $U(1)_D$ and the SM hypercharge is generated at one loop by the PM fields. The case in which the...
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 allow
measurements of $CP\!$ violation and the Cabibbo-Kobayashi-Maskawa
matrix elements in $B$-meson decay. In particular, we measure the
$CP$-violating phase $\phi_1/\alpha$ and...
Multi-Higgs-doublet models (NHDMs) has been gaining increasing popularity in beyond Standard Model (BSM) research, and people have been using it to address problems like dark matter, fermion mass hierarchies, and neutrino mass. Among these, there is steady growing literature (reaching a hundred) discussing the Four-Higgs-Doublet Model (4HDM). Finite symmetries play a pivotal role in NHDMs, yet...
