75 research outputs found
The p¯p → tbH± process at the Tevatron in HERWIG and PYTHIA simulations
No full textCharged Higgs boson production in association with a top quark could be the first indication of the existence of Higgs particles. The Tevatron Run-II started data-taking in April 2001 at GeV and could probe the existence of a charged Higgs boson beyond the current mass limit. We study the production process with Monte Carlo simulations in HERWIG and PYTHIA, comparing expected cross sections and basic selection variables
Hunting the elusive X17 in CEνNS at the ESS
No full textThe 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 12Cnuclei. Fits to the corresponding data point, as most probable explanation, to aspin-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 (ν)Nucleus Scattering (CEνNS) 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 CEνNS 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
Pair production of charged Higgs bosons in association with bottom quark pairs at the Large Hadron Collider
No full textWe study the process gg ? b¯bH+H? at large tan ?, 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 ofthe 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 tan ? 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
UV-complete Gauged Anomaly-free U(1) Froggatt-Nielsen Model
No full textWe investigate the possibility of understanding all fermion masses and
mixings within a gauged Froggatt-Nielsen framework. Continuing the work from
[J. Rathsman and F. Tellander, Phys. Rev. D \textbf{100}, 055032 (2019)] we
especially focus on a UV completion of this type of models. Independent of the
UV completion, we construct an anomaly-free two Higgs doublet model with a
gauged flavor symmetry and three right-handed neutrinos explaining all
observed masses and mixings in the fermion sector. We then investigate two
different UV completions: one through fermions and one through scalars. The
fermion completion has low lying Landau poles in the gague couplings while the
scalar completion is viable up to the gravity scale.Comment: 13 pages, 2 figure
UV-complete Gauged Anomaly-free U(1) Froggatt-Nielsen Model
No full textWe investigate the possibility of understanding all fermion masses and mixings within a gauged Froggatt-Nielsen framework. Continuing the work from [J. Rathsman and F. Tellander, Phys. Rev. D \textbf{100}, 055032 (2019)] we especially focus on a UV completion of this type of models. Independent of the UV completion, we construct an anomaly-free two Higgs doublet model with a gauged flavor symmetry and three right-handed neutrinos explaining all observed masses and mixings in the fermion sector. We then investigate two different UV completions: one through fermions and one through scalars. The fermion completion has low lying Landau poles in the gague couplings while the scalar completion is viable up to the gravity scale
Light Higgs bosons in phenomenological NMSSM
No full textWe 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 flavour 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
Higgs-boson-plus-photon production at the CERN Large Hadron Collider: A clean probe of the b-quark parton densities
No full textHiggs boson production in association with a high p(T) photon at the CERN Large Hadron Collider is analyzed, in the framework of the MSSM model, for the heavier neutral Higgs bosons. The request of an additional photon in the exclusive Higgs boson final state selects b-quark pairs among the possible initial partonic states, since gluon-gluon initial states are not allowed by C-parity conservation. Hence, the measurement of cross sections for neutral Higgs boson plus photon production can provide a clean probe of the b-quark density in the proton as well as of the b-quark Yukawa coupling. The suppression of the production rates by the b-quark electromagnetic coupling can be compensated by the enhanced Higgs boson Yukawa coupling to b's in the large tan beta regime. The Higgs boson decay into a tau-lepton pair is considered, and irreducible backgrounds with corresponding signal significances are evaluated
Vector-boson production of light Higgs pairs in 2-Higgs doublet models
No full textAt the Large Hadron Collider, we prove the feasibility to detect pair production of the lightest CP-even Higgs boson h of Type II 2-Higgs Doublet Models through qq(') → qq(')hh (vector-boson fusion). We also show that, through the hh → 4b decay channel in presence of heavy-flavour tagging, further exploiting forward/backward jet sampling, one has direct access to the λHhh triple Higgs coupling—which constrains the form of the Higgs potential
Production of light Higgs Pairs in 2-Higgs doublet models via the Higgs-strahlung process at the LHC
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ℤ 2 breaking effects in 2-loop RG evolution of 2HDM
No full textWe investigate the effects of a ℤ 2 symmetry in the CP-conserving Two-Higgs-Doublet-Model (2HDM); which is often imposed to prevent Flavor-Changing-Neutral-Currents (FCNCs) at tree-level. Specifically, we analyze how a breaking of the ℤ 2 symmetry spreads during renormalization group evolution; employing general 2-loop renormalization group equations that we have derived. Evolving the model from the electroweak to the Planck scale, we find that while the case of an exact ℤ 2 symmetric 2HDM is very constrained, a soft breaking of the ℤ 2 symmetry extends the valid parameter space regions. The effects of a hard ℤ 2 breaking in the scalar sector as well as the stability of the flavor alignment ansatz are also investigated. We find that while a hard breaking of the ℤ 2 symmetry in the potential is problematic, since it speeds up the growth of quartic couplings, the generated FCNCs are heavily suppressed. Conversely, we also find that hard ℤ 2 breaking in the Yukawa sector at most gives moderate ℤ 2 breaking in the potential; whereas the FCNCs can become quite sizable far away from the ℤ 2 symmetric regions
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