No Arabic abstract
We present a comprehensive analysis of observing a light Higgs boson in the mass range $70$ -- $110$ GeV at the 13/14 TeV LHC, in the context of the type-I two-Higgs-doublet model. The decay of the light Higgs to a pair of bottom quarks is dominant in most parts of the parameter space, except in the fermiophobic limit. Here its decay to bosons, (mainly a pair of photons), becomes important. We perform an extensive collider analysis for the $bbar{b}$ and $gamma gamma$ final states. The light scalar is tagged in the highly boosted regimes for the $b bar{b}$ mode to reduce the enormous QCD background. This decay can be observed with a few thousand fb$^{-1}$ of integrated luminosity at the LHC. Near the fermiophobic limit, the decay of the light Higgs to a pair of photons can even be probed with a few hundred fb$^{-1}$ of integrated luminosity at the LHC.
At the Large Hadron Collider (LHC), both the ATLAS and CMS Collaborations have been searching for light charged Higgs bosons via top (anti)quark production and decays channels, like $ppto t bar{t}$ with one top (anti)quark decaying into a charged Higgs boson and a $b$ (anti)quark, when the decay is kinematically open (i.e., when $m_{H^pm}lesssim m_t$). In this paper, we propose new searches at the LHC involving light charged Higgs bosons via their pair production channels like $ppto H^pm h/A$ and $ppto H^+ H^-$ in the 2-Higgs Doublet Model (2HDM) Type-I and -X scenarios. By focusing on the case where the heavy $H$ state plays the role of the Standard Model (SM)-like Higgs boson with a mass near 125 GeV, we study the aforementioned Higgs boson pair production channels and investigate their bosonic decays, such as $H^pm to W^{pm } h$ and/or $H^pm to W^{pm } A$. We demonstrate that for a light charged Higgs boson state, with $m_{H^pm}lesssim m_t$, at the LHC, such di-Higgs production and decay channels can give rise to signatures with event rates much larger than those emerging from $ppto tbar{t}to tbar{b} H^-$ + c.c. We specifically study $h/Ato bbar b$ and $tau^+tau^-$ decays. We, therefore, claim that the discussed combination of new production and decay modes can result in an alternative discovery channel for charged Higgs bosons lighter than the top (anti)quark at the LHC within the above two 2HDM Types. Finally, in order to motivate experimentalists in ATLAS and CMS to search for such signatures, we propose 16 Benchmark Points (BPs) which are compatible with both theoretical and experimental constraints.
We summarize the possible processes which may be used to search for a Higgs boson, of mass in the range 114-130 GeV, at the LHC. We discuss, in detail, two processes with rapidity gaps: exclusive Higgs production with tagged outgoing protons and production by Weak Boson Fusion, in each case taking H -> bbbar as the signal. We make an extensive study of all possible bbbar backgrounds, and discuss the relevant experimental issues. We emphasize the special features of these signals, and of their background processes, and show that they could play an important role in identifying a light Higgs boson at the LHC.
We analyse a light charged Higgs boson in the 2-Higgs Doublet Model (2HDM) Type-I, when its mass satisfies the condition $M_{H^{pm}} < M_{t}+M_{b}$ and the parameter space is consistent with theoretical requirements of self-consistency as well as the latest experimental constraints from Large Hadron Collider (LHC) and other data. Over such a parameter space, wherein the Standard Model (SM)-like state discovered at the LHC in 2012 is the heaviest CP-even state of the 2HDM, it is found that the decay modes of the charged Higgs boson are dominated by $H^{pm} rightarrow W^{pm *} h$. Furthermore, the light neutral Higgs boson $h$ dominantly decays into two photons. Under these conditions, we find that the production and decay process $ p p to H^pm h to {W^pm}^{(*)} h h to l u_{l} + 4 gamma$ ($l=e,mu$) is essentially background free. However, since the $W^{pm(*)}$ could be largely off-shell and the $h$ state is very light, so that both the lepton coming from the former and the photons coming from the latter could be rather soft, we perform here a full Monte Carlo (MC) analysis at the detector level demonstrating that such a $W^{pm} + 4gamma$ signal is very promising, as it would be yielding significant excesses at the LHC with an integrated luminosity of $L=$ 300 $fb^{-1}$ at both $sqrt{s}= 13$ and $14 ~text{TeV}$.
In models where an additional SU(2)-doublet that does not have couplings to fermions participates in electroweak symmetry breaking, the properties of the Higgs boson are changed. At tree level, in the neighborhood of the SM-like range of parameter space, it is natural to have the coupling to vectors, cV, approximately constant, while the coupling to fermions, cf, is suppressed. This leads to enhanced VBF signals of gamma gamma while keeping other signals of Higgses approximately constant (such as WW* and ZZ*), and suppressing higgs to tau tau. Sizable tree-level effects are often accompanied by light charged Higgs states, which lead to important constraints from b to s gamma and top to b H+, but also often to similarly sizable contributions to the inclusive h to gamma gamma signal from radiative effects. In the simplest model, this is described by a Type I 2HDM, and in supersymmetry is naturally realized with sister Higgs fields. In such a scenario, additional light charged states can contribute further with fewer constraints from heavy flavor decays. With supersymmetry, Grand Unification motivates the inclusion of colored partner fields. These G-quarks may provide additional evidence for such a model.
We study the Higgs boson $(h)$ decay to two light jets at the 14 TeV High-Luminosity-LHC (HL-LHC), where a light jet ($j$) represents any non-flavor tagged jet from the observational point of view. The decay mode $hto gg$ is chosen as the benchmark since it is the dominant channel in the Standard Model (SM), but the bound obtained is also applicable to the light quarks $(j=u,d,s)$. We estimate the achievable bounds on the decay branching fractions through the associated production $Vh (V=W^pm,Z)$. Events of the Higgs boson decaying into heavy (tagged) or light (un-tagged) jets are correlatively analyzed. We find that with 3000 fb$^{-1}$ data at the HL-LHC, we should expect approximately $1sigma$ statistical significance on the SM $Vh(gg)$ signal in this channel. This corresponds to a reachable upper bound ${rm BR}(hto jj) leq 4~ {rm BR}^{SM}(hto gg)$ at $95%$ confidence level. A consistency fit also leads to an upper bound ${rm BR}(hto cc) < 15~ {rm BR}^{SM}(hto cc)$ at $95%$ confidence level. The estimated bound may be further strengthened by adopting multiple variable analyses, or adding other production channels.