We use the CMS Open Data to examine the performance of weakly-supervised learning for tagging quark and gluon jets at the LHC. We target $\textit{Z}$+jet and dijet events as respective quark- and gluon-enriched mixtures and derive samples both from data taken in 2011 at 7 TeV, and from Monte Carlo. CWoLa and TopicFlow models are trained on real data and compared to fully-supervised classifiers trained on simulation. In order to obtain estimates for the discrimination power in real data, we consider three different estimates of the quark/gluon mixture fractions in the data. Compared to when the models are evaluated on simulation, we find reversed rankings for the fully- and weakly-supervised approaches. Further, these rankings based on data are robust to the estimate of the mixture fraction in the test set. Finally, we use TopicFlow to smooth statistical fluctuations in the small testing set, and to provide uncertainty on the performance in real data.

Australia

Matthew Dolan

Spain

John Gargalionis

Germany

Ayodele Ore

Quark-versus-gluon tagging in CMS Open Data with CWoLa and TopicFlow

We provide an exhaustive classification of three-family DFSZ axion models that have no cosmological domain wall problem. This result is obtained by making the Peccei-Quinn symmetry flavour dependent in certain specific ways, thus reinforcing a possible connection between the strong CP problem and the flavour puzzle. Known DFSZ flavour variants such as the top-specific model emerge as special cases. Key features of the phenomenology of these models are briefly discussed.

Peter Cox

Maaz Hayat

United States

Andrea Thamm

Raymond Volkas

Classification of three-family flavoured DFSZ axion models that have no domain wall problem

We analyse the experimental limits on the breaking scale of Pati-Salam extensions of the Standard Model. These arise from the experimental limits on rare-meson decay processes mediated at tree-level by the vector leptoquark in the model. This leptoquark ordinarily couples to both left- and right-handed SM fermions and therefore the meson decays do not experience a helicity suppression. We find that the current limits vary from   <math> <mi>O</mi> </math>  $$ \mathcal{O} $$ (80–2500) TeV depending on the choice of matrix structure appearing in the relevant three-generational charged-current interactions. We extensively analyse scenarios where additional fermionic degrees of freedom are introduced, transforming as complete Pati-Salam multiplets. These can lower the scales of Pati-Salam breaking through mass-mixing within the charged-lepton and down-quark sectors, leading to a helicity suppression of the meson decay widths which constrain Pati-Salam breaking. We find four multiplets with varying degrees of viability for this purpose: an SU(2) L/R  bidoublet, a pair of SU(4) decuplets and either an SU(2) L  or SU(2) R  triplet all of which contain heavy exotic versions of the SM charged leptons. We find that the Pati-Salam limits can be as low as   <math> <mi>O</mi> </math>  $$ \mathcal{O} $$ (5–150) TeV with the addition of these four multiplets. We also identify an interesting possible connection between the smallness of the neutrino masses and a helicity suppression of the Pati-Salam limits for three of the four multiplets.

Tomasz Dutka

Lowering the scale of Pati-Salam breaking through seesaw mixing

We examine the collider and dark matter phenomenology of the Standard Model extended by a hypercharge-zero SU(2) triplet scalar and gauge singlet scalar. In particular, we study the scenario where the singlet and triplet are both charged under a single ℤ2 symmetry. We find that such an extension is capable of generating the observed dark matter density, while also modifying the collider phenomenology such that the lower bound on the mass of the triplet is smaller than in minimal triplet scalar extensions to the Standard Model. A high triplet mass is in tension with the parameter space that leads to novel electroweak phase transitions in the early universe. Therefore, the lower triplet masses that are permitted in this extended model are of particular importance for the prospects of successful electroweak baryogenesis and the generation of gravitational waves from early universe phase transitions.

Nicole Bell

Leon Friedrich

China

Michael Ramsey-Musolf

A real triplet-singlet extended Standard Model: dark matter and collider phenomenology

A mistake has been found in the numerical code used to reproduce the bounds from proton beam dump experiments from ref. [1] in figures 2 and 7 of ref. [2]. Correcting this mistake leads to slightly stronger bounds as shown below. We note that this correction does not include recent improvements in the analysis of proton beam dump experiments [3]. Additional recent bounds on GeV-scale ALPs can be found in refs. [4–8].

Canada

Torben Ferber

Christopher Hearty

Felix Kahlhoefer

Kai Schmidt-Hoberg

Erratum to: Revised constraints and Belle II sensitivity for visible and invisible axion-like particles

We study the phenomenology of a hypercharge-zero SU (2) triplet scalar whose existence is motivated by two-step electroweak symmetry-breaking. We consider both the possibility that the triplets are stable and contribute to the dark matter density, or that they decay via mixing with the standard model Higgs boson. The former is constrained by disappearing charged track searches at the LHC and by dark matter direct detection experiments, while the latter is constrained by existing multilepton collider searches. We find that a two-step electroweak phase transition involving a stable triplet with a negative quadratic term is ruled out by direct detection searches, while an unstable triplet with a mass less than 230 GeV is excluded at 95% confidence level.

Two-step electroweak symmetry-breaking: theory meets experiment

We investigate the viability of electroweak baryogenesis in a model with a first order electroweak phase transition induced by the addition of two gauge singlet scalars. A vector-like lepton doublet is introduced in order to provide CP violating interactions with the singlets and Standard Model leptons, and the asymmetry generation dynamics are examined using the vacuum expectation value insertion approximation. We find that such a model is readily capable of generating sufficient baryon asymmetry while satisfying electron electric dipole moment and collider phenomenology constraints.

Electroweak baryogenesis with vector-like leptons and scalar singlets

We further investigate the case where new physics in the form of a massive Z ′ particle explains apparent measurements of lepton flavour non-universality in B → K (*) l + l − decays. Hadron collider sensitivities for direct production of such Z ′s have been previously studied in the narrow width limit for a μ + μ − final state. Here, we extend the analysis to sizeable decay widths and improve the sensitivity estimate for the narrow width case. We estimate the sensitivities of the high luminosity 14 TeV Large Hadron Collider (HL-LHC), a high energy 27 TeV LHC (HE-LHC), as well as a potential 100 TeV future circular collider (FCC). The HL-LHC has sensitivity to narrow Z ′ resonances consistent with the anomalies. In one of our simplified models the FCC could probe 23 TeV Z ′ particles with widths of up to 0.35 of their mass at 95% confidence level (CL). In another model, the HL-LHC and HE-LHC cover sizeable portions of parameter space, but the whole of perturbative parameter space can be covered by the FCC.

United Kingdom

B. Allanach

Tyler Corbett

Tevong You

Hadron collider sensitivity to fat flavourful Z ′s for   <math> <msub> <mi>R</mi> <msup> <mi>K</mi> <mfenced> <mo>∗</mo> </mfenced> </msup> </msub> </math>  $$ {R}_{K^{\left(\ast \right)}} $$

Light pseudoscalars interacting pre-dominantly with Standard Model gauge bosons (so-called axion-like particles or ALPs) occur frequently in extensions of the Standard Model. In this work we review and update existing constraints on ALPs in the keV to GeV mass region from colliders, beam dump experiments and astrophysics. We furthermore provide a detailed calculation of the expected sensitivity of Belle II, which can search for visibly and invisibly decaying ALPs, as well as long-lived ALPs. The Belle II sensitivity is found to be substantially better than previously estimated, covering wide ranges of relevant parameter space. In particular, Belle II can explore an interesting class of dark matter models, in which ALPs mediate the interactions between the Standard Model and dark matter. In these models, the relic abundance can be set via resonant freeze-out, leading to a highly predictive scenario consistent with all existing constraints but testable with single-photon searches at Belle II in the near future.

Revised constraints and Belle II sensitivity for visible and invisible axion-like particles

Large field excursions are required in a number of axion models of inflation. These models also possess global cosmic strings, around which the axion follows a path mirroring the inflationary trajectory. Cosmic strings are thus an interesting theoretical laboratory for the study of transplanckian field excursions. We describe connections be-tween various effective field theory models of axion monodromy and study the classical spacetimes around their supercritical cosmic strings. For small decay constants f &lt; M p and large winding numbers n &gt; M p /f , the EFT is under control and the string cores undergo topological inflation, which may be either of exponential or power-law type. We show that the exterior spacetime is nonsingular and equivalent to a decompactifying cigar geometry, with the radion rolling in a potential generated by axion flux. Signals are able to circumnavigate infinite straight strings in finite but exponentially long time, t ∼ e Δ a / M p . For finite loops of supercritical string in asymptotically flat space, we argue that if topological inflation occurs, then topological censorship implies transplanckian censorship, or that external observers are forbidden from threading the loop and observing the full excursion of the axion.