Maximum Entropy Inferences on the Axion Mass in Models with Axion-Neutrino Interaction

In this work we use the Maximum Entropy Principle (MEP) to infer the mass of an axion which interacts to photons and neutrinos in an effective low energy theory. The Shannon entropy function to be maximized is suitably defined in terms of the axion branching ratios. We show that MEP strongly constrains the axion mass taking into account the current experimental bounds on the neutrinos masses. Assuming that the axion is massive enough to decay into all the three neutrinos and that MEP fixes all the free parameters of the model, the inferred axion mass is in the interval $0.1\$eV$\ <m_{A}<0.2$ eV, which can be tested by forthcoming experiments such as IAXO. However, even in the case where MEP fixes just the axion mass and no other parameter, we found that $0.1$ eV $< m_A < 6.3$ eV in the DFSZ model with right-handed neutrinos. Moreover, a light axion, allowed to decay to photons and the lightest neutrino only, is determined by MEP as a viable dark matter candidate.Comment: 13 pages, 5 figures, typos corrected, figures update

Inferences on the Higgs Boson and Axion Masses through a Maximum Entropy Principle

The Maximum Entropy Principle (MEP) is a method that can be used to infer the value of an unknown quantity in a set of probability functions. In this work we review two applications of MEP: one giving a precise inference of the Higgs boson mass value; and the other one allowing to infer the mass of the axion. In particular, for the axion we assume that it has a decay channel into pairs of neutrinos, in addition to the decay into two photons. The Shannon entropy associated to an initial ensemble of axions decaying into photons and neutrinos is then built for maximization.Comment: Contributed to the 13th Patras Workshop on Axions, WIMPs and WISPs, Thessaloniki, May 15 to 19, 201

Searching for Elko dark matter spinors at the CERN LHC

The aim of this work is to explore the possibility to discover a fermionic field with mass dimension one, the Elko field, in the Large Hadron Collider (LHC). Due to its mass dimension, an Elko can only interact either with Standard Model (SM) spinors and gauge fields at 1-loop order or at tree level through a quartic interaction with the Higgs field. In this Higgs portal scenario, the Elko is a viable candidate to a dark matter constituent which has been shown to be compatible with relic abundance measurements from WMAP and direct dark matter--nucleon searches. We propose a search strategy for this dark matter candidate in the channel $pp \rightarrow l^+ l^- + \not\!\! E_T$ at the $\sqrt{s}=14$ TeV LHC. We show the LHC potential to discover the Elko considering a triple Higgs-Elko coupling as small as $\sim 0.5$ after 1 pb$^{-1}$ of integrated luminosity. Some phenomenological consequences of this new particle and its collider signatures are also discussed.Comment: 7 pages, 3 figure

The 7% Rule: A Maximum Entropy Prediction on New Decays of the Higgs Boson

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 flavour violating decays of the Higgs boson, and a dark gauge boson model.Comment: 12 pages, 5 figures. Version published in Nuclear Physics

Constraining Elko Dark Matter at the LHC with Monophoton Events

A mass dimension one fermion, also known as Elko, constitutes a dark matter candidate which might interact with photons at the tree level in a specific fashion. In this work, we investigate the constraints imposed by unitarity and LHC data on this type of interactions using the search for new physics in monophoton events. We found that Elkos which can explain the dark matter relic abundance mainly through electromagnetic interactions are excluded at the 95\%CL by the 8 TeV LHC data for masses up to 1 TeV.Comment: 6 pages, 4 figure

Variational Autoencoders for Regression: Recovering Fully Leptonic bbˉW+W−b\bar{b}W^+W^- in Di-Higgs Searches

The search for double Higgs production in $b\bar{b}W^+W^-$, where both $W$ bosons decay to leptons, has been rehabilitated as a good option to look for that key process to the Standard Model scalar sector study in 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 $hh,t\bar{t}\to b\bar{b}W^+W^-\to b\bar{b}\ell^+\ell^{\prime -}\nu_\ell\bar{\nu}_{\ell^\prime}$. The algorithm predicts the invariant mass of non-resonant $hh$ irrespective of the trilinear coupling, even for events whose Higgs self-couplings were never presented to it. 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 $\chi^2$ between trilinear coupling hypotheses based on binned invariant mass distributions of $b\bar{b}\ell^+\ell^{\prime -}\nu_\ell\bar{\nu}_{\ell^\prime}$.Comment: 29 pages, 10 figures, 2 table