Charged-Higgs-boson production at the LHC: Next-to-leading-order supersymmetric QCD corrections

127

Search for charged Higgs bosons decaying via H ± → τ ± ν in fully hadronic final states using pp collision data at √ s = 8 TeV with the ATLAS detectorThe ATLAS collaboration E-mail: atlas.publications@cern.ch Abstract:The results of a search for charged Higgs bosons decaying to a τ lepton and a neutrino, H ± → τ ± ν, are presented. The analysis is based on 19.5 fb −1 of proton-proton collision data at √ s = 8 TeV collected by the ATLAS experiment at the Large HadronCollider. Charged Higgs bosons are searched for in events consistent with top-quark pair production or in associated production with a top quark, depending on the considered H ± mass. The final state is characterised by the presence of a hadronic τ decay, missing transverse momentum, b-tagged jets, a hadronically decaying W boson, and the absence of any isolated electrons or muons with high transverse momenta. The data are consistent with the expected background from Standard Model processes. A statistical analysis leads to 95% confidence-level upper limits on the product of branching ratios B(t → bH ± ) × B(H ± → τ ± ν), between 0.23% and 1.3% for charged Higgs boson masses in the range 80-160 GeV. It also leads to 95% confidence-level upper limits on the production cross section times branching ratio, σ(pp -1 - JHEP03(2015)088be through top-quark decays t → bH + , for charged Higgs boson masses (m H + ) smaller than the top-quark mass (m top ). At the LHC, top quarks are produced predominantly through tt production. In this paper, the contribution to t → bH + which may arise from single top-quark production is neglected, since the signal production cross section through this channel is very small with respect to tt production. A diagram illustrating the leadingorder production mechanism is shown on the left-hand side of figure 1. For charged Higgs boson masses larger than m top , the main H + source at the LHC is through associated production with a top quark. An additional b-quark can also appear in the final state. The leading-order production mechanisms in two different approximations are illustrated in the centre and right-hand side diagrams of figure 1: in the four-flavour scheme (4FS) b-quarks are dynamically produced, whereas in the five-flavour scheme (5FS) the b-quark is also considered as an active flavour inside the proton. Their cross sections are matched according to ref. [12], and an evaluation of the two schemes can be found in ref.[13].In the MSSM, the Higgs sector can be completely determined at tree level by one of the Higgs boson masses, here taken to be m H + , and tan β, the ratio of the vacuum expectation values of the two Higgs doublets. For m H + < m top , the decay via H + → τ + ν is dominant for tan β > 2 and remains sizeable for 1 < tan β < 2. For higher m H + , the decay via H + → τ + ν is still significant, especially for large values of tan β [14]. The combined LEP lower limit for the charged Higgs boson mass is about 90 GeV [15]. The Tevatron experiments placed upper limits on B(t → bH + ) in the 15-20% range for m H +...

Section: Resultsmentioning

confidence: 99%

Search for charged Higgs bosons decaying via H ± → τ ± ν in fully hadronic final states using pp collision data at s $$ \sqrt{s} $$ = 8 TeV with the ATLAS detector

Collaboration¹

2015

127

“…Many works have been done in the comparison of the 5FNS and 4FNS Schemes, see refs. [78][79][80][81][82][83][84], etc. A latest comparison in the 4FNS and 5FNS schemes in ref.…”

Section: General Descriptionmentioning

confidence: 99%

NLO QCD corrections to Single Top and W associated photoproduction at the LHC with forward detector acceptances

Sun

Liu

Wang

et al. 2015

In this paper we study the Single Top and W boson associated photoproduction via the main reaction pp → pγp → pW ± t + Y at the 14 TeV Large Hadron Collider (LHC) up to next-to-leading order (NLO) QCD level assuming a typical LHC multipurpose forward detector. We use the Five-Flavor-Number Schemes (5FNS) with massless bottom quark assumption in the whole calculation. Our results show that the QCD NLO corrections can reduce the scale uncertainty. The typical K-factors are in the range of 1.15 to 1.2 which lead to the QCD NLO corrections of 15% to 20% correspond to the leading-order (LO) predictions with our chosen parameters.

“…Direct charged Higgs production in the top-bottom fusion channel typically has crosssections O(1 pb) [3] and discovery would be fairly difficult in this channel [4,5]. If the charged Higgs mass is lower than the top mass, it is possible to bypass this problem by looking for charged Higgs bosons in top decays (t → H + b), taking advantage of the very large tt production cross-section.…”

Section: Jhep04(2014)140mentioning

confidence: 99%

“…(For the kinematics the Φ finite width effects are included.) 3 The constraint from Standard Model h → W + W − searches…”

Section: Total Cross-sectionsmentioning

confidence: 99%

A new avenue to charged Higgs discovery in multi-Higgs models

Dermíšek

Hall

Lunghi

et al. 2014

Current searches for the charged Higgs at the LHC focus only on the τ ν, cs, and tb final states. Instead, we consider the process pp → Φ → W ± H ∓ → W + W − A where Φ is a heavy neutral Higgs boson, H ± is a charged Higgs boson, and A is a light Higgs boson, with mass either below or above the bb threshold. The cross-section for this process is typically large when kinematically open since H ± → W ± A can be the dominant decay mode of the charged Higgs. The final state we consider has two leptons and missing energy from the doubly leptonic decay of the W + W − and possibly additional jets; it is therefore constrained by existing SM Higgs searches in the W + W − channel. We extract these constraints on the cross-section for this process as a function of the masses of the particles involved. We also apply our results specifically to a type-II two Higgs doublet model with an extra Standard-Model-singlet and obtain new and powerful constraints on m H ± and tan β. We point out that a slightly modified version of this search, with more dedicated cuts, could be used to possibly discover the charged Higgs, either with existing data or in the future.