We study the soft and collinear (SV) contributions to inclusive Higgs-boson production in gluon-gluon fusion at four loops. Using recent progress for the quark and gluon form factors and Mellin moments of splitting functions, we are able to complete the soft-gluon enhanced contributions exactly in the limit of a large number of colours, and to a sufficiently accurate numerical accuracy for QCD. The four-loop SV contributions increase the QCD cross section at 14 TeV by 2.7% and 0.2% for the standard choices mu_R=m_H and mu_R=m_H/2 of the renormalization scale, and reduce the scale uncertainty to below +-3%. As by-products, we derive the complete delta(1-x) term for the gluon-gluon splitting function at four loops and its purely Abelian contributions at five loops, and provide a numerical result for the single pole of the four-loop gluon form factor in dimensional regularization. Finally we present the closely related fourth-order coefficients D_4 for the soft-gluon exponentiation of Higgs-boson and Drell-Yan lepton-pair production.
Pseudoscalar and charged Higgs bosons production in the processes $μ^+ μ^-\to P^0_i Z^0$, $μ^+μ^- \to H^{\pm}W^{\mp}$ within the models with several Higgs doublets and singlets is considered.
Theoretical overview on phenomenology of Higgs boson and SUSY Higgs boson at a future linear collider experiment is given as a Higgs and SUSY Higgs working group summary report for LCWS 2000.
We explore the possibility of distinguishing the SM-like MSSM Higgs boson from the SM Higgs boson via Higgs boson pair production at future muon collider. We study the behavior of the production cross section in SM and MSSM with Higgs boson mass for various choices of MSSM parameters tan βand m\sub A. We observe that at fixed CM energy, in the SM, the total cross section increases with the increase in Higgs boson mass whereas this trend is reversed for the MSSM case. The changes that occur for the MSSM case in comparison to the SM predictions are quantified in terms of the relative percentage …
The influence of the QCD structure of the weak bosons on the Higgs boson production in $e$-$p$ scattering is studied. The energy and Higgs boson mass dependence of the cross-section, following from the new contributions, is calculated.
Compared with the MSSM or the NMSSM with a low λ, λ-SUSY theory with a large λaround one has been deemed as a most natural realization of NMSSM. In this work, we treat the next-to-lightest CP-even Higgs boson as the SM-like Higgs boson in λ-SUSY and study the properties of the Higgs bosons and the pair production of the SM-like Higgs boson by considering various experiment constraints. We find that naturalness plays an important role in selecting the parameter space of λ-SUSY. In the most natural region of parameter space, the triple self coupling of the SM-like Higgs boson compared with its S…
The production of Higgs bosons in weak boson fusion has the second largest cross section among Higgs-production processes at the LHC. As such, this process plays an important role in detailed studies of Higgs interactions with vector bosons. In this paper we extend the available description of Higgs boson production in weak boson fusion by considering anomalous $HVV$ interactions and NNLO QCD radiative corrections at the same time. We find that, while leading order QCD predictions are too uncertain to allow for detailed studies of the anomalous couplings, NLO QCD results are sufficiently preci…
The left-right twin Higgs(LRTH) model predicts the existence of three additional Higgs bosons: one neutral Higgs $ϕ^{0}$ and a pair of charged Higgs bosons $ϕ^{\pm}$. In this paper, we studied the production of a pair of charged and neutral Higgs bosons associated with standard model gauge boson $Z$ at the ILC, i.e., $e^{+}e^{-}\rightarrow Zϕ^{+}ϕ^{-}$ and $e^{+}e^{-}\rightarrow Zϕ^{0}ϕ^{0}$. We calculate the production rate and present the distributions of the various observables, such as, the distributions of the energy and the transverse momenta of final $Z$-boson and charged Higgs boson $ϕ…
We discuss the ${\cal O}(α_s)$ QCD radiative corrections to Higgs boson production in the limit in which the top quark is much heavier than the Higgs boson. The subleading corrections, of ${\cal O} (α_s M_H^2/M_{\rm top}^2)$, are presented for the decay $H\rightarrow γγ$ and shown to be small.
Searches for charged Higgs bosons are an integral part of current and future investigations at the LHC. The LHC Higgs Cross Section Working Group (LHCHXSWG) was created to provide cross sections, branching ratios, analysis strategies etc. for Higgs boson searches at the LHC. We briefly review progress and results for charged Higgs bosons in and for the LHCHXSWG.
The total cross section for Higgs boson production via the dominant gluon fusion mechanism including NLO [two-loop] QCD corrections can be calculated numerically with the program HIGLU. The QCD corrections are included for arbitrary Higgs and quark masses and increase the cross section at the LHC by up to a factor of 2. The source code HIGLU provides the evaluation of the production of the Standard Model [SM] Higgs boson as well as the neutral Higgs bosons of the minimal supersymmetric extension [MSSM]. The program HDECAY determines the decay widths and branching ratios of the Higgs bosons wit…
We consider the two-Higgs-doublet model with explicit CP-violation, where the effective Higgs potential is not CP-invariant at the tree-level. Three neutral Higgs bosons of the model are the mixtures of CP-even and CP-odd bosons which exist in the CP-conserving limit of the theory. The mass spectrum and tree-level couplings of the neutral Higgs bosons to gauge bosons and fermions are significantly dependent on the parameters of the Higgs boson mixing matrix. We calculate the Higgs-gauge boson, Higgs-fermion, triple and quartic Higgs self-interactions in the MSSM with explicit CP-violation in t…
In the case of minimal supersymmetric extension of the Standard Model (MSSM), when the pseudoscalar Higgs boson mass is less than the supersymmetry energy scale, the effective theory at the electroweak scale is a two-Higgs-doublet model. We diagonalize the mass matrix of the general two-Higgs-doublet model, expressing Higgs boson self-couplings in terms of two mixing angles and four Higgs boson masses, and derive in a compact form the complete set of Feynman rules, including quartic couplings in the Higgs sector, for the case of CP-violating potential. Some processes of double and triple Higgs…
We compute the total cross-section for direct production of the pseudoscalar Higgs boson in hadron collisions at next-to-next-to-leading order (NNLO) in perturbative QCD. The O(alpha_s^2) QCD corrections increase the NLO production cross-section by approximately 20-30 per cent.
We study an upper bound on masses of additional scalar bosons from the electroweak precision data and theoretical constraints such as perturbative unitarity and vacuum stability in the two Higgs doublet model taking account of recent Higgs boson search results. If the mass of the Standard-Model-like Higgs boson is rather heavy and is outside the allowed region by the electroweak precision data, such a discrepancy should be compensated by contributions from the additional scalar bosons. We show the upper bound on masses of the additional scalar bosons to be about 2 $(1)$ TeV for the mass of the…
We consider the triple coupling of the Higgs boson in the context of the gauge-Higgs unification scenario. We show that the triple coupling of the Higgs boson in this scenario generically deviates from SM prediction since the Higgs potential in this scenario has a periodicity. We calculate the coupling in the five-dimensional $SU(3)$ x $U(1)_X$ gauge-Higgs unification model and obtain 70% deviation from the SM prediction.
We explain the current excess seen at the Large Hadron Collider via the $gg\to H\toγγ$ channel in the search for a neutral Higgs boson in terms of both singly (marginally) and doubly (predominantly) charged Higgs bosons predicted by the Higgs Triplet Model.
We show that it is possible to construct models in which the width of the Higgs boson is arbitrary - either smaller or larger than a standard model Higgs boson of the same mass. There are no new fields into which the Higgs boson decays. Instead, the coupling of the Higgs boson to the gauge bosons is adjusted. We construct and analyze weakly--coupled models with arbitrary--width Higgs bosons to investigate the phenomenology one might find in a strongly interacting model. In any such model new physics must enter at a mass scale which decreases as the Higgs boson width is adjusted away from its s…
We present updated predictions for Higgs boson production at the Tevatron and the LHC and we review their corresponding uncertainties. We report on a study of the impact of QCD radiative corrections on the Higgs boson search at the Tevatron.
We consider the measurement of the trilinear couplings of the neutral Higgs bosons in the Minimal Supersymmetric Standard Model~(MSSM) at a high energy $e^+ e^-$ linear collider in the light of the discovery of a Higgs boson at the CERN Large Hadron Collider~(LHC). We identify the state observed at the LHC with the lightest Higgs boson~($h^0$) of the MSSM, and impose the constraints following from this identification, as well as other experimental constraints on the MSSM parameter space. In order to measure trilinear neutral Higgs couplings, we consider different processes where the heavier Hi…
The Higgs boson mass problem is considered in the next-to-minimal supersymmetric standard model for the case of the spontaneous CP violation. The renormalization group equations for the gauge, Yukawa and scalar coupling constants, the effective Higgs potential and lower experimental bounds on Higgs boson and chargino masses are analyzed. The restrictions on the Higgs boson masses are found.
We present the NLO QCD corrections for light Higgs pair production via vector boson fusion at the LHC within the CP conserving type II two higgs doublet model in the form of a fully flexible parton--level Monte Carlo program. Scale dependences on integrated cross sections and distributions are reduced with QCD K-factors of order unity.
We show that radiative corrections to the Higgs potential in supersymmetric theories with large tan beta generically lead to large differences in the light Higgs boson decay branching fractions compared to those of the standard model Higgs boson. In contrast, the light Higgs boson production rates are largely unaffected. We identify W h associated production followed by Higgs boson decays to photons or to leptons via W W* as potential experimental probes of these theories.
We present a next-to-leading order calculation of Higgs boson production in vector-boson fusion processes interfaced to shower Monte Carlo programs, implemented according to the POWHEG method.
It is proposed to replace the Higgs boson of the standard model by a Lorentz- and gauge-invariant combination of SU(2) gauge bosons. A pair of Higgs bosons is identified with pairs of gauge bosons by setting their mass Lagrangians equal to each other. That immediately determines the mass of the composite Higgs boson. It becomes simply half of the vacuum expectation value of the standard Higgs boson, which matches the observed mass with tree-level accuracy (2%). The two parameters of the standard Higgs potential are replaced by five one-loop self-interactions of the SU(2) gauge bosons, derived …
We calculate the two-loop QCD corrections to the production of the neutral supersymmetric Higgs bosons via the gluon fusion mechanism at hadron colliders, including the contributions of squark loops. To a good approximation, these additional contributions lead to the same QCD corrections as in the case where only top and bottom quark loops are taken into account. The QCD corrections are large and increase the Higgs production cross sections significantly.
The leading $m_H$ radiative correction to the Higgs decay width into a pair of weak vector bosons is calculated at the two--loop level, using the equivalence theorem in Landau gauge. The result indicates the breakdown of perturbation theory if the Higgs boson is heavier than $\sim 930$ GeV, in spite of the smallness of the one--loop radiative correction.
We calculate next-to-leading order (NLO) QCD corrections to electroweak Higgs plus three jet production. Both vector boson fusion (VBF) and Higgs-strahlung type contributions are included along with all interferences. The calculation is implemented within the Matchbox NLO framework of the Herwig++ event generator.
We study the decays of Higgs bosons to a lighter Higgs boson and a virtual gauge boson in the context of the non-supersymmetric Two-Higgs-Doublet-Model (2HDM). We consider the phenomenological impact at LEP2 and find that such decays, when open, may be dominant in regions of parameter space and thus affect current Higgs boson search techniques. Three-body decays would be a way of producing light neutral Higgs bosons which have so far escaped detection at LEP due to suppressed couplings to the $Z$, and are of particular importance in the 2HDM (Model I) which allows both a light fermiophobic Hig…
We demonstrate that Higgs boson production in fusion processes is accompanied by large azimuthal asymmetry. This asymmetry can be used to facilitate detection of Higgs boson events. We also demonstrate that the double Higgs boson production at threshold is a very appropriate process to test the existence of new physics at higher energy.
One loop contributions to the CP even-CP odd Higgs boson mixings arising from contributions due to exchange of a vectorlike multiplet are computed under the Higgs boson mass constraint. The vectorlike multiplet consists of a fourth generation of quarks and a mirror generation. This sector brings in new CP phases which can be large consistent with EDM constraints. In this work we compute the contributions from the exchange of quarks and mirror quarks $t_{4L}, t_{4R}, T_{L}, T_{R}$, and their scalar partners, the squarks and the mirror squarks. The effect of their contributions to the Higgs boso…
In the gauge-Higgs unification the 4D Higgs field becomes a part of the extra-dimensional component of the gauge potentials. In the $SO(5) \times U(1)$ gauge-Higgs unification in the Randall-Sundrum warped spacetime the electroweak symmetry is dynamically broken through the Hosotani mechanism. The Higgs bosons become absolutely stable, and become the dark matter of the universe. The mass of the Higgs boson is determined from the WMAP data to be about 70 GeV.
Recently obtained NNLO exact corrections for Higgs and Pseudoscalar Higgs boson production in hadron colliders are compared with approximate ones. As shown before, it is found that there is a range of a proper variable where these corrections differ little.
The phenomenological model of an extra U(1) neutral gauge Z' boson coupled to heavy quarks is presented. In particular, we discuss the probability for a light $Z_{2}$ mass eigenstate decay into a bound state composed of heavy quarks via Higgs boson emission.
Many of the new physics models predicts a light Higgs boson similar to the Higgs boson of the Standard Model (SM) and also extra scalar bosons. Beyond the search channels for a SM Higgs boson, the future collider experiments will explore additional channels that are specific to extended Higgs sectors. We study the charged Higgs boson production within the framework of two Higgs doublet models (THDM) in the proton-proton collisions at the FCC-hh collider. With an integrated luminosity of 500 fb$^{-1}$ at very high energy frontier, we obtain a significant coverage of the parameter space and dist…
We investigate the differential branching ratio, branching ratio, differential forward-backward asymmetry, the forward-backward asymmetry of the lepton pair and the lepton polarization asymmetry of the exclusive $B\to τ^+ τ^- γ$ decay in the general two Higgs doublet model including the neutral Higgs boson effects. We analyse the dependencies of these quantities on the model parameters and also on the neutral Higgs boson effects. We found that they get considerable enhancement from the two Higgs doublet model compared to the standard model and neutral Higgs boson effects are quite sizable.
Higgs boson productions at the LHC will serve as a sensitive probe of various little Higgs models. In this work we comparatively study two littlest Higgs models with different T-parity constructions through examining their effects in three production processes of the Higgs boson at the LHC, namely the productions of a single Higgs, a Higgs-pair, as well as a Higgs boson associated with a pair of top and anti-top quarks. The two models are characterized by predicting a top partner canceling the Higgs mass quadratic divergence contributed by the top quark with even and odd T-parity, respectively…
We review the role of a muon collider in the study of Higgs bosons via production in the s-channel. Very precise measurements of a Standard Model-like Higgs boson mass and total width can be performed, and may lead to a discrimination between a Standard Model Higgs boson and the light Higgs boson of the minimal supersymmetric theory. The heavier Higgs bosons from a supersymmetric theory or an exotic Higgs sector can be studied in the s-channel. A muon collider may play a crucial role in separating the overlapping signals for two heavy nearly degenerate Higgs bosons, and may play an important r…
The dominance of $h\to ηη$ decay mode for the intermediate mass Higgs boson is highly motivated to solve the little hierarchy problem and to ease the tension with the precision data. However, the discovery modes for $m_h \alt 150$ GeV, $h \to γγ$ and $W/Z h \to (\ellν/\ell \bar \ell) (b\bar b)$, will be substantially affected. We show that $h \to ηη\to 4b$ is complementary and we can use this decay mode to detect the intermediate Higgs boson at the LHC, via $Wh$ and $Zh$ production. Requiring at least one charged lepton and 4 $B$-tags in the final state, we can identify a clean Higgs boson sig…
We examine the potential for detecting and studying Higgs bosons at a photon-photon collider facility associated with a future linear collider. Our study incorporates realistic $\gam\gam$ luminosity spectra based on the most probable available laser technology. Results include detector simulations. We study the cases of: a) a SM-like Higgs boson; b) the heavy MSSM Higgs bosons; c) a Higgs boson with no $WW/ZZ$ couplings from a general two Higgs doublet model.
We present an estimate of the next-to-leading order QCD corrections to mixed QCD-electroweak contribution to Higgs boson production cross section in gluon fusion, combining the recently computed three-loop virtual corrections and the approximate treatment of real emission in the soft approximation. We find that the NLO QCD corrections to mixed QCD-electroweak contributions are nearly identical to NLO QCD corrections to QCD Higgs production. Our result confirms an earlier estimate of these ${\cal O}\left( α\, α_s^2 \right)$ effects in arXiv:0811.3458 [hep-ph] and provides further support for th…
We replace the scalar Higgs doublet with a vector Higgs boson doublet to the unified electroweak W-S model and find most of important features of W-S model are kept unchanged only the Higgs boson now become vector bosons. Lorentz invariance has been carefully discussed. The most important challenge is there will be three massless vector Higgs bosons. The remarkable effect is the possible suppression of the flavorchanging neutral current compare to the multi-Higgs model.
We have reconsidered the Higgs boson search via the "golden mode" for Tevatron. It is shown that this mode will give opportunity to observe the Higgs boson with mass up to 300 GeV before Tevatron shutdown.
The measurement of the trilinear and quartic Higgs self-couplings is necessary for the reconstruction of the Higgs potential. This way the Higgs mechanism as the origin of electroweak symmetry breaking can be tested. The couplings are accessible in multi-Higgs production processes at the LHC. In this paper we investigate the prospects of measuring the trilinear Higgs coupling in composite Higgs models. In these models, the Higgs boson emerges as a pseudo-Goldstone boson of a strongly interacting sector, and the Higgs potential is generated by loops of the Standard Model (SM) gauge bosons and f…
We discuss the phenomenology of many Higgs doublet model - the model where each Higgs isodoublet couples with each own quark and lepton with relatively big Yukawa coupling constants. Namely, we discuss the discovery potential of the Higgs bosons at LHC and find lower mass limits on nonstandard Higgs bosons from FNAL data.
The threshold dependence and angular correlations of Higgs-strahlung in e+e- collisions can be used to demonstrate the spinless nature of the Standard Model Higgs boson. This method, and its possible extention to heavy neutral MSSM Higgs bosons, is discussed.
The associated production of a Higgs boson with a b quark is a discovery mode for an MSSM Higgs boson at large tan beta. We compute the SUSY QCD corrections from gluino and squark loops to this process and combine them with the order alpha_s^2 NLO QCD corrections to obtain reliable predictions for the rate. Finally, we compare our results with an effective Lagrangian approximation which includes only the low energy corrections from squark and gluino loops to the b- bbar- Higgs vertices.
We study Higgs boson production and decay in a certain class of Little Higgs models with T-parity in which some T-parity partners of the Standard Model (SM) fermions gain their masses through Yukawa-type couplings. We find that the Higgs boson production cross section of a 120 GeV Higgs boson at the CERN LHC via gg fusion process at one-loop level could be reduced by about 45%, 35% and 20%, as compared to its SM prediction, for a relatively low new particle mass scale f = 600, 700 and 1000 GeV, respectively. On the other hand, the weak boson fusion cross section is close to the SM value. Furth…
The search for the Higgs boson is one of the main physics goals of the Large Hadron Collider (LHC) and its two multi-purpose experiments, ATLAS and CMS. Vector boson fusion is the second largest production process for a standard model Higgs boson at the LHC and offers excellent means for background suppression. This paper gives an overview of the prospects of Higgs boson searches using vector boson fusion at the LHC. For a standard model Higgs boson, the decay channels H->tautau, H->WW and H->gammagamma are discussed. The discovery potential in the framework of the MSSM is summarized.
We derive analytic formulas for the radiatively corrected mass of the scalar Higgs boson in the framework of the minimal supersymmetric standard model (MSSM). Since the scalar-top-quark mass in our analysis include terms proportional to the gauge couplings in the 1-loop effective potential, the radiatively corrected mass of the scalar Higgs boson partially contains the gauge boson contributions. At the 1-loop level, the upper bound on the lighter scalar Higgs boson mass can be increased about 20 GeV in favor of the partial contributions of the gauge bosons. Thus the improved absolute upper bou…
Neutral Higgs-boson pair production provides the possibility of studying the trilinear Higgs couplings at future high-energy colliders. We present the QCD corrections to the gluon-initiated processes in the limit of a heavy top quark in the loops and the Drell-Yan-like pair production of scalar and pseudoscalar Higgs particles. The pp cross sections are discussed for LHC energies within the Standard Model and its minimal supersymmetric extension. The QCD corrections are large, enhancing the total cross sections significantly.
The production of single and doubly charged Higgs bosons associated with standard model gauge boson $Z_L$ in $e^{+}e^{-}$ colliders are examined. The sensitivity of these processes on the littlest Higgs model parameters in the range of compatibility with electroweak precision observables are analyzed. The possibility of detecting lepton flavor violation processes are also discussed.
The Georgi-Machacek model predicts the existence of four neutral Higgs bosons, one of which can be identified as the 125-GeV Higgs boson. The latest Higgs data favor the parameter space of small mixing angle alpha between the two custodial singlets of the model. The other two neutral Higgs bosons belong respectively to the custodial triplet and quintet. We study the general decay and production properties of these particles in the small-alpha scenario. Constraints on the SU(2)_L triplet vacuum expectation value are obtained as a function of the exotic Higgs boson masses using latest ATLAS data…
