Searches for additional Higgs bosons and for vector leptoquarks in ττ final states in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

Abstract

Three searches are presented for signatures of physics beyond the standard model (SM) in ττ final states in proton-proton collisions at the LHC, using a data sample collected with the CMS detector at $$ \sqrt{s} $$ s = 13 TeV, corresponding to an integrated luminosity of 138 fb−1. Upper limits at 95% confidence level (CL) are set on the products of the branching fraction for the decay into τ leptons and the cross sections for the production of a new boson ϕ, in addition to the H(125) boson, via gluon fusion (ggϕ) or in association with b quarks, ranging from $$ \mathcal{O} $$ O (10 pb) for a mass of 60 GeV to 0.3 fb for a mass of 3.5 TeV each. The data reveal two excesses for ggϕ production with local p-values equivalent to about three standard deviations at mϕ = 0.1 and 1.2 TeV. In a search for t-channel exchange of a vector leptoquark U1, 95% CL upper limits are set on the dimensionless U1 leptoquark coupling to quarks and τ leptons ranging from 1 for a mass of 1 TeV to 6 for a mass of 5 TeV, depending on the scenario. In the interpretations of the $$ {M}_{\textrm{h}}^{125} $$ M h 125 and $$ {M}_{\textrm{h},\textrm{EFT}}^{125} $$ M h , EFT 125 minimal supersymmetric SM benchmark scenarios, additional Higgs bosons with masses below 350 GeV are excluded at 95% CL.

95 GeV light Higgs in the top-pair-associated diphoton channel at the LHC in the minimal dilaton model*

“…with 8 TeV 19.7 data [4]. This was followed in 2018 by a 2.8σ local (1.3σ global) excess in the 95.3 GeV diphoton invariant mass, using a combination of 13 TeV 35.9 data [5]. In 2022, observations by the CMS of a 2.6σ local (2.3σ global) excess in the 95−100 GeV range with 13 TeV 138 data further supported these hints [6].…”

Impact of new experimental data on the C2HDM: the strong interdependence between LHC Higgs data and the electron EDM

“…This concerns mainly the masses of the BSM scalars, which then turns out to have a large impact on the LHC phenomenology and corresponding constraints on the C2HDM. The difference of results in Type-II according to the different prescription of the fermion masses, as discussed above, has its origin in the application of cross-section limits from LHC searches -more specifically, searches for scalar resonances produced via gluon-fusion with subsequent decay in τ τ final JHEP05(2024)127 states performed by CMS at 13 TeV [97]. 9 In the right plot of figure 3, we show the parameter points from the two scans that we have performed in Type-II, with the lightest scalar mass m h 1 on the horizontal axis and the gluon-fusion production cross section for h 1 at 13 TeV on the vertical axis.…”

“…This possibility is now practically excluded, as we discussed in section 3.1. This exclusion follows from the combination of stringent eEDM constraints and limits from LHC searches for additional Higgs bosons at 13 TeV, most notably from searches for di-τ resonances below 125 GeV [97]. The only still viable option for sizable |c o b | happens if two conditions are verified: first, if the parameters are very fine-tuned, such that cancellations between different contributions to the eEDM occur at (or below) the percent-level; second, if the pole masses for top-quark and τ -lepton and the running bottom-quark mass m b (m b ) are used for the computation of the eEDM.…”

LHC tau-pair production constraints on $a_\tau$ and $d_\tau$

“…In this work we point out that constraints on a τ and d τ that are competitive or even superior to those quoted in (1) and ( 2) can be derived from the tau-pair production measurements [10][11][12] obtained in proton-proton (pp) collisions at the LHC Run II. The important observation that leads to this conclusion is that, as a simple consequence of the anomalous moments corresponding to Wilson coefficients of non-renormalisable operators, the contributions of a τ and d τ to the Drell-Yan (DY) production process pp → τ + τ − are enhanced at high energies compared to the SM background.…”