arXiv subjects

Gabriela Lichtenstein

Publications and source records attributed to Gabriela Lichtenstein.

5 recordsLinked to original sources

arXiv2026

Updated Bounds on the Minimal Left-Right Symmetric Model from LHC Dilepton Resonance Searches

The Left-Right model is a popular extension of the Standard Model that features three new neutral gauge bosons, $W^{\pm}_R$ and $Z_R$. Collider searches for a Left-Right symmetry are often concentrated on the charged right-handed current, but in this work, we take advantage of the dilepton data at the LHC with center-of-mass energy of 13 TeV and 139 fb$^{-1}$ of integrated luminosity to place lower mass bounds in the $Z_R$ mass based on the $p\,p \rightarrow Z_{R} \rightarrow \ell^{+} \, \ell^{-}$ process. We vary the $SU(2)_R$ gauge coupling from $g_{R}=0.4$ to $g_{R}=1.0$, and impose $M_{Z_R}>4.9$ TeV and $M_{Z_{R}}>6.1$ TeV, respectively. Lastly, we put our findings into perspective with $W_R$ searches at the LHC and show that our limits cover an unexplored region of parameter space, where the right-handed neutrino is heavier than the $W_R$ boson.

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arXiv2025

Z and Higgs boson decays with doubly-charged scalars at one-loop: current constraints, future sensitivities, and application to lepton-triality models

We analyse the $Z$ and Higgs boson decays $Z\to \ell^+ \ell^- $ ($\ell = e, μ,τ$), $H\to γγ$ and $H\to Zγ$ that are induced at one-loop level in models with a doubly-charged isosinglet scalar. After discussing current constraints, we derive the parameter space that will be probed by the HL-LHC and the possible future colliders the ILC, CEPC and FCC. We then apply those constraints to lepton triality models which are based on a discrete $Z_3$ family symmetry and were recently studied in the context of charged-lepton flavour-violating processes at Belle II and the proposed $μ^+ μ^+$ and $μ^+ e^-$ collider known as $μ$TRISTAN. We find that the future constraints that can be imposed by $Z \to \ell^+ \ell^-$ on the lepton flavour conserving couplings of the triality models reduce the viable parameter space to probe lepton flavour violating processes. The constraints from Higgs boson decays are the first on the Higgs portal sector of the triality models.

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arXiv2023

Complementarity of $μ$TRISTAN and Belle II in searches for charged-lepton flavour violation

We analyse the potential of the proposed $μ^+ μ^+$ and $μ^+ e^-$ collider $μ$TRISTAN to complement the searches for charged-lepton flavour-violation (CLFV) that can be carried out by Belle II. $μ$TRISTAN offers the possibility of directly producing and studying new resonances that could mediate CLFV for a certain range of masses. In addition, we find that it can produce competitive bounds to those from Belle II for cases where the new resonance lies beyond direct reach. We illustrate these points with three $Z_3$ "lepton triality" models, where we also find an example that can only be probed by $μ$TRISTAN. These three models feature doubly-charged scalars, denoted $k_{1,2,3}$ respectively, that induce both CLFV and flavour-conserving processes. Tree-level $k_1$ exchange induces the CLFV scattering process $μ^+ e^- \to e^+ τ^-$, while $k_2$ interactions induce $μ^+ μ^+ \to τ^+ e^+$, $μ^+ e^- \to τ^+ μ^-$ and make a non-SM contribution to the flavour-conserving scattering $μ^+ μ^+ \to μ^+ μ^+$. The $k_3$ model has a non-SM contribution to the flavour-conserving process $μ^+ e^- \to μ^+ e^-$. Other scattering processes involving $k_1$, $k_2$ or $k_3$ are not relevant for $μ$TRISTAN and outside the scope of our analysis. We quantify the sensitivity of $μ$TRISTAN for each of these processes. For the $k_1$ and $k_2$ cases we compare the $μ$TRISTAN reach to the expected sensitivity of Belle II to the crossing symmetry related CLFV $τ$ decays.

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arXiv2018

Displaced Vertices from Hidden Glue

We consider the phenomenology of glueball production and decay in theories with hidden glue. We focus on the case of folded supersymmetry (FSUSY) , where there is an unbroken $SU(3)$ gauge theory in the absence of light matter, leading to the formation of glueballs. We study their production through the annihilation of folded squarks into hidden gluons at the LHC, and model their fragmentation into glueballs. We obtain the distribution of displaced vertices, which is directly determined by the folded squark mass scale. Although here we specifically apply it to FSUSY, the procedure to model the hidden glue fragmentation into glueballs can be generalized to other similar theories.

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arXiv2013

Resonances from Quiver Theories at the LHC

We consider the collider signals of spin-one resonances present in full-hierarchy quiver theories of electroweak symmetry breaking. These four-dimensional theories result from the deconstruction of warped extra dimensional models and have very distinct phenomenological features when the number of sites is small. We study a class of generic scenarios in these theories where the color gauge group as well as the electroweak sector, propagate in the quiver diagram. These scenarios correspond to various specific models of electroweak symmetry breaking and fermion masses. We focus on the minimum resonant content and its main features: the presence of heavy and narrow spin one resonances. We derive bounds from the LHC data on the color-octet and color-singlet excited gauge bosons from their decays to jets and top pairs, and show their dependence on the number of sites in the quiver. We also compare them with the bounds derived from flavor violation.

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