The search for double Higgs production in   <math> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> <msup> <mi>W</mi> <mo>+</mo> </msup> <msup> <mi>W</mi> <mo>−</mo> </msup> </math>  $$ b\overline{b}{W}^{+}{W}^{-} $$ , where both W bosons decay to leptons, has been rehabilitated as a good option to investigate key processes within the Standard Model scalar sector at the LHC. The missing neutrinos, however, hinder the reconstruction of useful information like the Higgs pair mass, which is very sensitive to the trilinear Higgs self-coupling. We present a solution to that problem using a Variational Autoencoder for Regression (VAER) to reconstruct the Higgs and top pairs decays hh,   <math> <mi>t</mi> <mover> <mi>t</mi> <mo>¯</mo> </mover> <mo>→</mo> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> <msup> <mi>W</mi> <mo>+</mo> </msup> <msup> <mi>W</mi> <mo>−</mo> </msup> <mo>→</mo> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> <msup> <mi>ℓ</mi> <mo>+</mo> </msup> <msup> <mi>ℓ</mi> <mrow> <mo>′</mo> <mo>−</mo> </mrow> </msup> <msub> <mi>ν</mi> <mi>ℓ</mi> </msub> <msub> <mover> <mi>ν</mi> <mo>¯</mo> </mover> <msup> <mi>ℓ</mi> <mo>′</mo> </msup> </msub> </math>  $$ t\overline{t}\to b\overline{b}{W}^{+}{W}^{-}\to b\overline{b}{\ell}^{+}{\ell}^{\prime -}{\nu}_{\ell }{\overline{\nu}}_{\ell^{\prime }} $$ . The algorithm predicts the invariant mass of non-resonant hh independently of specific trilinear coupling values, even for events where the Higgs self-coupling were not included during its training. VAER is also able to identify a new Higgs resonance in an unsupervised way, showing generalization power for events not presented in its training phase. Finally, we demonstrate that VAER prediction is as useful to statistical inference as ground truth simulated distributions by computing a χ 2 between trilinear coupling hypotheses based on binned invariant mass distributions of   <math> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> <msup> <mi>ℓ</mi> <mo>+</mo> </msup> <msup> <mi>ℓ</mi> <mrow> <mo>′</mo> <mo>−</mo> </mrow> </msup> <msub> <mi>ν</mi> <mi>ℓ</mi> </msub> <msub> <mover> <mi>ν</mi> <mo>¯</mo> </mover> <msup> <mi>ℓ</mi> <mo>′</mo> </msup> </msub> </math>  $$ b\overline{b}{\ell}^{+}{\ell}^{\prime -}{\nu}_{\ell }{\overline{\nu}}_{\ell^{\prime }} $$ .

Brazil

Alexandre Alves

Eduardo Silva Almeida

Igor Mesquita

Variational autoencoders for regression: recovering fully leptonic   <math> <mi>b</mi> <mover> <mi>b</mi> <mo>¯</mo> </mover> <msup> <mi>W</mi> <mo>+</mo> </msup> <msup> <mi>W</mi> <mo>−</mo> </msup> </math>  $$ b\overline{b}{W}^{+}{W}^{-} $$  in di-Higgs searches

We explore single and double flavor-violating scalar (flavon) production at the 13 and 14 TeV LHC in an effective field theory formulation where flavons always change the flavor of the Standard Model fermions. When those scalars couple to mass, their flavor-changing couplings to top quarks and tau leptons are favored. Focusing on the mass region below the top-quark mass, we find couplings that fit the muon (<math><mrow><mi>g</mi><mo>−</mo><mn>2</mn></mrow></math>) discrepancy and avoid several current experimental constraints. We determine the potential of the LHC to exclude or discover such a new physics scenario with clean signatures consisting of same-sign tau leptons and the simultaneous observation of resonances in the tau plus electron or muon invariant mass. We found that in the double production mode, effective couplings down to order <math><mrow><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup><mtext> </mtext><mtext> </mtext><mrow><msup><mrow><mi>TeV</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></mrow></math> can be probed for flavon masses in the 10–170 GeV range at the 14 TeV HL-LHC, but couplings down to <math><mn>0.1</mn><mtext> </mtext><mtext> </mtext><msup><mi>TeV</mi><mrow><mo>−</mo><mn>1</mn></mrow></msup></math> can already be excluded at 95% confidence level with data collected from the 13 TeV LHC in the same mass interval. We also explore the impact of sizeable diagonal flavon couplings on the prospects of LHC for the signals we propose.

Alex G. Dias

Eduardo da Silva Almeida

Diego S. V. Gonçalves

Same-sign taus signatures of maximally flavor-violating scalars at the LHC

We study the lepton-induced resonant production of color-adjoint leptons (leptogluons) at the LHC, employing the lepton parton density function of the proton. We demonstrate that this production mechanism can be useful to extend the LHC ability to search for leptogluons beyond purely quark/gluon-initiated production processes up to <math><mo>∼</mo><mn>3.5</mn><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math> leptogluon masses and <math><mi>O</mi><mo>(</mo><mn>1</mn><mo>)</mo><mtext> </mtext><mtext> </mtext><mi>TeV</mi></math> compositeness scales. Discerning leptogluons from scalar and vector leptoquarks is also possible in this channel, given a data sample containing the order of 100 signal events. We argue that the resonant channel can be combined with leptogluon pair and associated leptogluon-lepton productions to boost exclusion limits and discovery prospects at the LHC.

Spain

Oscar J. P. Éboli

Chile

F. S. Queiroz

Resonant lepton-gluon collisions at the Large Hadron Collider

Neutrinos, dark matter, and long-lived neutral particles traverse the particle detectors unnoticed, carrying away information about their parent particles and interaction sources needed to reconstruct key variables like resonance peaks in invariant mass distributions. In this work, we show that a k-nearest neighbors regressor algorithm combined with deep neural network classifiers, a kNNNN, is able to accurately recover binned distributions of the fully leptonic WW mass of a new heavy Higgs boson and its Standard Model backgrounds from the observable detector level information at disposal. The output of the regressor can be used to train even stronger classifiers to separate signals and backgrounds in the fully leptonic case and guarantee the selection of on-mass-shell Higgs bosons with enhanced statistical significance. The method assumes previous knowledge of the event classes and model parameters, thus suitable for post-discovery studies.

C. Yamaguchi

Reconstruction of missing resonances combining nearest neighbors regressors and neural network classifiers

We present a comprehensive study of the electroweak interactions using the available Higgs and electroweak diboson production results from LHC runs 1 and 2 as well as the electroweak precision data in terms of the dimension-six operators. Under the assumption that no new tree-level sources of flavor violation or violation of the universality of the weak current are introduced, the analysis involves 21 operators. We assess the impact of the data on kinematic distributions for the Higgs production at the LHC by comparing the results obtained by including the simplified template cross-section data with those in which only total Higgs signal strengths are considered. We also compare the results obtained when including the dimension-six anomalous contributions to order <math><mrow><mn>1</mn><mo>/</mo><msup><mrow><mi>Λ</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></math> and to order <math><mrow><mn>1</mn><mo>/</mo><msup><mrow><mi>Λ</mi></mrow><mrow><mn>4</mn></mrow></msup></mrow></math>. As an illustration of the LHC potential to indirectly learn about specific forms of new physics, we adapt the analysis to constrain the parameter space for a few simple extensions of the standard model which generate a subset of the dimension-six operators at tree level.

United States

M. C. Gonzalez–Garcia

Electroweak legacy of the LHC run II

Axion-like particles (ALPs) and Higgs bosons can interact in scalar sectors beyond the Standard Model, leading the Higgs boson to decay into pairs of gluons and photons through the ALP interaction and giving rise to resonances in the decay products of the process h → aa → gg + γγ, resembling a spectral-line analysis. We explore this signature to constrain an ALP effective field theory formulation. Our analyses show that the forthcoming runs of the LHC will be capable of probing the ALP-Higgs interaction in the ALP mass range from 0.5 to 60 GeV using an automatized search strategy that adapts to different ALP masses in inclusive jets plus photons final states. Such interaction can also be tested in mass regions where the two and four-photon search channels are currently ineffective.

A. Dias

D. Lopes

Jets and photons spectroscopy of Higgs-ALP interactions

Conditions for strong first-order phase transition and generation of observable gravitational wave (GW) signals are very restrictive to the profile of the Higgs potential. Working in the minimal extension of the SM with a new gauge singlet real scalar, we show that the production of signals relevant for future GW experiments, such as LISA, can favor depleted resonant and non-resonant di-Higgs rates at colliders for phenomenologically relevant regimes of scalar mixing angles and masses for the heavy scalar. We perform a comprehensive study on the emergence of these di-Higgs blind spot configurations in GWs and also show that di-boson channels, ZZ and WW, can restore the phenomenological complementarities between GW and collider experiments in these parameter space regimes.

Dorival Gonçalves

Tathagata Ghosh

Huai-Ke Guo

Kuver Sinha

Di-Higgs blind spots in gravitational wave signals

The entropy of the Higgs boson decay probabilities distribution in the Standard Model (SM) is maximized for a Higgs mass value that is less than one standard deviation away from the current experimental measurement. This successful estimate of the Higgs mass encourages us to propose tests of the Maximum Entropy Principle (MEP) as a tool for theoretical inferences in other instances of Higgs physics. In this letter, we show that, irrespective of the extension of the SM predicting a new Higgs boson decay channel, its branching ratio can be inferred to be around 7% in such a way that the new entropy of decays still exhibits a maximum at the experimental Higgs mass. This 7% rule can be tested whenever a new Higgs decay channel is found. In order to illustrate the MEP predictions, we apply the MEP inference to Higgs portal models, Higgs-axion interactions, lepton flavor violating decays of the Higgs boson, and a dark gauge boson model.

Alex Gomes Dias

Roberto da Silva

The 7% rule: A maximum entropy prediction on new decays of the Higgs boson

In this work, prospects to probe an overlooked facet of axion-like particles (ALPs) — their potential couplings to sterile neutrinos — are presented. We found that mono-photon searches have the potential to constrain ALP couplings to sterile neutrinos when a new heavy scalar boosts the ALP decay yields. Working within an effective field theory (EFT) approach, we scan the parameters space to establish the reach of the 13 TeV LHC to probe such couplings. We found regions of the parameters space evading several experimental constraints that can be probed at the LHC. Moreover, a complementary role between the LHC and various experiments that search for axions and ALPs can be anticipated for models where ALPs interact with sterile neutrinos. We also present the UV realization of a model having an axion-like particle, a heavy scalar and sterile neutrinos whose parameters are spanned by our EFT approach. The proposed model contains a type of seesaw mechanism for generating masses for the active neutrinos along with sterile neutrinos involving the high energy scale of the spontaneous breaking of the global symmetry associated to the ALP. Some benchmark points of this model can be discovered at the 13 TeV LHC with 300 fb −1.

A.G. Dias

Germany

D.D. Lopes

Probing ALP-sterile neutrino couplings at the LHC

We present a complementarity study of gravitational waves and double Higgs production in the 4b channel, exploring the gauge singlet scalar extension of the SM. This new physics extension serves as a simplified benchmark model that realizes a strongly first-order electroweak phase transition necessary to generate the observed baryon asymmetry in the universe. In calculating the signal-to-noise ratio of the gravitational waves, we incorporate the effect of the recently discovered significant suppression of the gravitational wave signals from sound waves for strong phase transitions, make sure that supercooled phase transitions do complete and adopt a bubble wall velocity that is consistent with a successful electroweak baryogenesis by solving the velocity profiles of the plasma. The high-luminosity LHC sensitivity to the singlet scalar extension of the SM is estimated using a shape-based analysis of the invariant 4b mass distribution. We find that while the region of parameter space giving detectable gravitational waves is shrunk due to the new gravitational wave simulations, the qualitative complementary role of gravitational waves and collider searches remain unchanged.