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A bstract The so-called X 17 particle has been proposed in order to explain a very significant resonant behaviour (in both the angular separation and invariant mass) of e + e − pairs produced during a nuclear transition of excited 8 Be, 4 He and 12 C nuclei. Fits to the corresponding data point, as most probable explanation, to a spin-1 object, which is protophobic and has a mass of approximately 16.7 MeV, which then makes the X 17 potentially observable in Coherent Elastic neutrino ( ν ) Nucleus Scattering (CE ν NS) at the European Spallation Source (ESS). By adopting as theoretical framework a minimal extension of the Standard Model (SM) with a generic U(1) ′ gauge group mixing with the hypercharge one of the latter, which can naturally accommodate the X 17 state compliant with all available measurements from a variety of experiments, we predict that CE ν NS at the ESS will constitute an effective means to probe this hypothesis, even after allowing for the inevitable systematics associated to the performance of the planned detectors therein.

We consider scenarios in the next-to-minimal supersymmetric model (NMSSM) where the CP-odd and charged Higgs bosons are very light. As we demonstrate, these can be obtained as simple deformations of existing phenomenological MSSM benchmarks scenarios with parameters defined at the weak scale. This offers a direct and meaningful comparison to the MSSM case. Applying a wide set of up-to-date constraints from both high-energy collider and flavor physics, the Higgs boson masses and couplings are studied in viable parts of parameter space. The LHC phenomenology of the light Higgs scenario for neutral and charged Higgs boson searches is discussed.

At the Large Hadron Collider, we prove the feasibility to detect pair production of the lightest CP -even Higgs boson h of a Type II 2-Higgs Doublet Model through the process (Higgs-strahlung, V = W ± ,Z ), in presence of two decays. We also show that, through such production and decay channels, one has direct access to the following Higgs self-couplings, thus enabling one to distinguish between a standard and the Supersymmetric version of the above model: λ Hhh — which constrains the form of the Higgs potential — as well as λ W ± H ∓ h and λ Z Ah — which are required by gauge invariance. Unfortunately, such claims cannot be extended to the Minimal Supersymmetric Standard Model, where the extraction of the same signals is impossible.

We investigate the viability of observing charged Higgs bosons ( ) produced in association with bosons at the CERN large hadron collider, using the leptonic decay and hadronic decay, within different scenarios of the minimal supersymmetric standard model (MSSM) with both real and complex parameters. Performing a parton level study we show how the irreducible standard model background from jets can be controlled by applying appropriate cuts and find that the size of a possible signal depends on the cuts needed to suppress QCD backgrounds and misidentifications. In the standard maximal mixing scenario of the MSSM we find a viable signal for large and intermediate masses ( ) when using softer cuts ( , 50 GeV), whereas for harder cuts ( , 100 GeV) we only find a viable signal for very large ( ). We have also investigated a special class of MSSM scenarios with large mass splittings among the heavy Higgs bosons where the cross-section can be resonantly enhanced by factors up to one hundred, with a strong dependence on the -violating phases. Even so we find that the signal after cuts remains small except for small masses ( ) when using the softer cuts. Finally, in all the scenarios we have investigated we have only found small -asymmetries.

The so-called X17 particle has been proposed in order to explain a very significant resonant behaviour (in both the angular separation and invariant mass) of e+e- pairs produced during a nuclear transition of excited 8Be, 4He and 12C nuclei. Fits to the corresponding data point, as most probable explanation, to a spin-1 object, which is protophobic and has a mass of approximately 16.7 MeV, which then makes the X17 potentially observable in Coherent Elastic neutrino (nu) Nucleus Scattering (CE nu NS) at the European Spallation Source (ESS). By adopting as theoretical framework a minimal extension of the Standard Model (SM) with a generic U(1)' gauge group mixing with the hypercharge one of the latter, which can naturally accommodate the X17 state compliant with all available measurements from a variety of experiments, we predict that CE nu NS at the ESS will constitute an effective means to probe this hypothesis, even after allowing for the inevitable systematics associated to the performance of the planned detectors therein.

We study the process gg→b¯bH+H− at large tanβ, where it represents the dominant production mode of charged Higgs boson pairs in a Type II 2-Higgs doublet model, including the minimal supersymmetric standard model. The ability to select this signal would in principle enable the measurements of some triple-Higgs couplings, which in turn would help understanding the structure of the extended Higgs sector. We outline a selection procedure that should aid in disentangling the Higgs signal from the main irreducible background. This exploits a signature made up by “four b -quark jets, two light-quark jets, a τ-lepton and missing energy”. While, for tanβ≳30 and over a significant MH± range above the top mass, a small signal emerges already at the Large Hadron Collider after 100 fb -1 , ten times as much luminosity would be needed to perform accurate measurements of Higgs parameters in the above final state, rendering this channel a primary candidate to benefit from the so-called “Super” Large Hadron Collider option, for which a tenfold increase in instantaneous luminosity is currently being considered.

We study the process \\(gg b b H^ + H^-\\) at large \\(\\), where it represents the dominant production mode of charged Higgs boson pairs in a Type II 2-Higgs doublet model, including the minimal supersymmetric standard model. The ability to select this signal would in principle enable the measurements of some triple-Higgs couplings, which in turn would help understanding the structure of the extended Higgs sector. We outline a selection procedure that should aid in disentangling the Higgs signal from the main irreducible background. This exploits a signature made up by “four b-quark jets, two light-quark jets, a \\(\\)-lepton and missing energy”. While, for \\(30\\) and over a significant \\(M_H^\\) range above the top mass, a small signal emerges already at the Large Hadron Collider after 100 fb-1, ten times as much luminosity would be needed to perform accurate measurements of Higgs parameters in the above final state, rendering this channel a primary candidate to benefit from the so-called “Super” Large Hadron Collider option, for which a tenfold increase in instantaneous luminosity is currently being considered.

We investigate the viability of observing charged Higgs bosons ( ) produced in association with bosons at the CERN large hadron collider, using the leptonic decay and hadronic decay, within different scenarios of the minimal supersymmetric standard model (MSSM) with both real and complex parameters. Performing a parton level study we show how the irreducible standard model background from jets can be controlled by applying appropriate cuts and find that the size of a possible signal depends on the cuts needed to suppress QCD backgrounds and misidentifications. In the standard maximal mixing scenario of the MSSM we find a viable signal for large and intermediate masses ( ) when using softer cuts ( ,  50 GeV), whereas for harder cuts ( , 100 GeV) we only find a viable signal for very large ( ). We have also investigated a special class of MSSM scenarios with large mass splittings among the heavy Higgs bosons where the cross-section can be resonantly enhanced by factors up to one hundred, with a strong dependence on the -violating phases. Even so we find that the signal after cuts remains small except for small masses ( ) when using the softer cuts. Finally, in all the scenarios we have investigated we have only found small -asymmetries.

We report on detailed Monte Carlo comparisons of selection variables to separate tbH ± signal events from the standard model tt̄ background using an iterative discriminant analysis (IDA) method. While kinematic differences exist between the two processes whenever , the exploration of the spin difference between the charged Higgs and the W ± gauge boson becomes crucial in the particularly challenging case of near degeneracy of the charged Higgs boson mass with the W ± mass. The TAUOLA package is used to decay the tau leptons emerging from the charged Higgs and W ± boson decays taking the spin difference properly into account. We demonstrate that, even if the individual selection variables have limited discriminant power, the IDA method achieves a significant separation between the expected signal and background. For both Tevatron and LHC energies, the impact of the spin effects and H ± mass on the separation of signal and background has been studied quantitatively. The effect of a hard transverse momentum cut to remove QCD background has been studied and it is found that the spin effects remain important. The separation is expressed in purity versus efficiency curves. The study is performed for charged Higgs boson masses between the W ± mass and near the top mass.

We investigate the viability of observing charged Higgs bosons (H±) produced in association with W bosons at the CERN Large Hadron Collider, using the leptonic decay H+ → and hadronic W decay, within the Minimal Supersymmetric Standard Model. Performing a parton level study we show how the irreducible Standard Model background from W + 2 jets can be controlled by applying appropriate cuts. In the standard mmaxh scenario we find a viable signal for large tan β and intermediate H± mmasses (~ mt).