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At least 1,063 records · Page 59

Exotic Higgs boson decay modes as a harbinger of S{sub 3} flavor symmetry

Discrete symmetries employed to explain flavor mixing and mass hierarchies can be associated with an enlarged scalar sector which might lead to exotic Higgs decay modes. In this paper, we explore such a possibility in a scenario with S{sub 3} flavor symmetry which requires three scalar SU(2) doublets. The spectrum is fixed by minimizing the scalar potential, and we observe that the symmetry of the model leads to tantalizing Higgs decay modes potentially observable at the CERN Large Hadron Collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Global fits of the nonuniversal Higgs model

We carry out global fits to the nonuniversal Higgs Model (NUHM), applying all relevant present-day constraints. We present global probability maps for the NUHM parameters and observables (including collider signatures, direct, and indirect detection quantities), both in terms of posterior probabilities and in terms of profile likelihood maps. We identify regions of the parameter space where the neutralino dark matter in the model is either binolike, or else higgsinolike with mass close to 1 TeV and a spin-independent scattering cross section {approx}10{sup -9}-10{sup -8} pb. We trace the occurrence of the higgsinolike region to be a consequence of a mild focusing effect in the running of one of the Higgs masses, the existence of which in the NUHM we identify in our analysis. Although the usual binolike neutralino is more prominent, higgsinolike dark matter cannot be excluded, however its significance strongly depends on the prior and statistics used to assess it. We note that, despite experimental constraints often favoring different regions of parameter space to the constrained minimal supersymmetric standard model, most observational consequences appear fairly similar, which will make it challenging to distinguish the two models experimentally.

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Uncertainties on exclusive diffractive Higgs boson and jet production at the LHC

Two theoretical descriptions of exclusive diffractive jets and Higgs production at the LHC were implemented into the FPMC generator: the Khoze, Martin, Ryskin model and the Cudell, Hernandez, Ivanov, Dechambre exclusive model. We then study the uncertainties. We compare their predictions to the CDF measurement and discuss the possibility of constraining the exclusive Higgs production at the LHC with early measurements of exclusive jets. We show that the present theoretical uncertainties can be reduced with such data by a factor of 5.

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Leptogenesis in B-L gauged supersymmetry with MSSM Higgs sector

We study a modified version of a U(1){sub B-L} gauged MSSM that was recently shown to produce a new source of leptogenesis through the CP asymmetry of sneutrinos and antisneutrinos [K. S. Babu, Yanzhi Meng, and Zurab Tavartkiladze, Phys. Lett. B 681, 37 (2009)]. By taking all superpotential terms and couplings between the MSSM Higgs and B-L scalar sectors into account we find that the model allows a large enough CP violation to explain the observed baryon number to entropy ratio. Monte Carlo analysis shows that a large amount of CP violation can be produced in the decays of the B-L Higgs bosons and that there are two dominating channels that drive CP violation.

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Possibility of observing an MSSM charged Higgs boson in association with a W boson at the LHC

The possibility of observing associated production of the charged Higgs and W boson in the framework of the minimal supersymmetric standard model (MSSM) at LHC is studied. Both leptonic and hadronic decays of the W boson are studied while the charged Higgs boson is considered to decay to a {tau} lepton and a neutrino. Therefore two search categories are defined based on the leptonic and hadronic final states, i.e., l{tau}+E{sub T}{sup miss} and jj{tau}+E{sub T}{sup miss} where l=e or {mu} and j is a light jet from W decay. The discovery chance of the two categories is evaluated at an integrated luminosity of 300 fb{sup -1} at LHC. It is shown that both leptonic and hadronic final states have the chance of discovery at high tan{beta}. Finally 5{sigma} and 3{sigma} contours are provided for both search categories.

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Hadronic production of a MSSM Higgs boson with a pair of stops at the LHC

We present the next-to-leading order supersymmetric-QCD corrections to the production of a light neutral minimal supersymmetric standard model Higgs boson with a pair of supersymmetric scalar partners of the top quark at next-to-leading order at the LHC. We study the dependence of the lowest order total cross section on both the renormalization/factorization scale and the Higgs mass in the framework of minimal supergravity, taking the point SPS1a as a benchmark, for the numerical calculations. The renormalization/factorization scale dependence of the lowest order total cross section is strong. Including the next-to-leading order supersymmetric-QCD corrections significantly reduces and stabilizes the dependence of the lowest order total cross section on the renormalization/factorization scale.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

One-loop QCD and Higgs bosons to partons processes using six-dimensional helicity and generalized unitarity

We combine the six-dimensional helicity formalism of Cheung and O'Connell with D-dimensional generalized unitarity to obtain a new formalism for computing one-loop amplitudes in dimensionally regularized QCD. With this procedure, we simultaneously obtain the pieces that are constructible from four-dimensional unitarity cuts and the rational pieces that are missed by them, while retaining a helicity formalism. We illustrate the procedure using four- and five-point one-loop amplitudes in QCD, including examples with external fermions. We also demonstrate the technique's effectiveness in next-to-leading order QCD corrections to Higgs processes by computing the next-to-leading order correction to the Higgs plus three positive-helicity gluons amplitude in the large top-quark mass limit.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Absence of spontaneous CP violation in multi-Higgs doublet extension of MSSM

We show that in the multi-Higgs extension of minimal supersymmetric standard model, which has N-pairs of Higgs doublets (called NHMSSM), it is impossible to break CP spontaneously, if we do not allow for fine-tuning relations between parameters. The result holds true even in the presence of spontaneous R-parity breaking.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Associated Higgs-W-Boson Production at Hadron Colliders: A Fully Exclusive QCD Calculation at NNLO

We consider QCD radiative corrections to standard model Higgs-boson production in association with a W boson in hadron collisions. We present a fully exclusive calculation up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. To perform this NNLO computation, we use a recently proposed version of the subtraction formalism. Our calculation includes finite-width effects, the leptonic decay of the W boson with its spin correlations, and the decay of the Higgs boson into a bb pair. We present selected numerical results at the Tevatron and the LHC.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

The Discovery of the Higgs Boson: America's Role

The discovery of the Higgs boson was an international endeavor, involving thousands of physicists from across the world. While the accelerator at which the experimental work was done is located on Europe, the US supplied more physicists than any other single country. America had a very large role in the discovery of the Higgs particle and continues to have a leading role in the ongoing studies of the boson's properties. This video describes some of the contributions of U.S. universities and laboratories.

43 PARTICLE ACCELERATORS↗

Big Mysteries: The Higgs Mass

With the discovery of what looks to be the Higgs boson, LHC researchers are turning their attention to the next big question, which is the predicted mass of the newly discovered particles. When the effects of quantum mechanics is taken into account, the mass of the Higgs boson should be incredibly high...perhaps upwards of a quadrillion times higher than what was observed. In this video, Fermilab's Dr. Don Lincoln explains how it is that the theory predicts that the mass is so large and gives at least one possible theoretical idea that might solve the problem. Whether the proposed idea is the answer or not, this question must be answered by experiments at the LHC or today's entire theoretical paradigm could be in jeopardy.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Got a Minute? Which Higgs did we find?

Dr. John Stupak talks about the discovery of the Higgs boson. Did scientists find the Higgs boson predicted back in 1964 or did they find just one of a group of particles, with the others still to be found?

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Light Higgs And Dark Photon Searches at BABAR

Several new-physics (NP) models predict the existence of low-mass Higgs states and light dark matter candidates. Previous BABAR searches have given null results for these new states and have excluded large regions of the NP models parameter space. We report on new searches on light Higgs and light dark matter at BABAR using the 516 fb -1 of data collected with the BABAR detector at the PEP-II asymmetric-energy e + e - collider at the SLAC National Accelerator Laboratory

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

8D likelihood effective Higgs couplings extraction framework in h → 4ℓ

We present an overview of a comprehensive analysis framework aimed at performing direct extraction of all possible effective Higgs couplings to neutral electroweak gauge bosons in the decay to electrons and muons, the so called ‘golden channel’. Our framework is based primarily on a maximum likelihood method constructed from analytic expressions of the fully differential cross sections for h → 4l and for the dominant irreducible $ q\overline{q} $ → 4l background, where 4l = 2e2μ, 4e, 4μ. Detector effects are included by an explicit convolution of these analytic expressions with the appropriate transfer function over all center of mass variables. Utilizing the full set of observables, we construct an unbinned detector-level likelihood which is continuous in the effective couplings. We consider possible ZZ, Zγ, and γγ couplings simultaneously, allowing for general CP odd/even admixtures. A broad overview is given of how the convolution is performed and we discuss the principles and theoretical basis of the framework. This framework can be used in a variety of ways to study Higgs couplings in the golden channel using data obtained at the LHC and other future colliders.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Phenomenological analysis of Higgs boson production through gluon fusion in association with jets

We present a detailed phenomenological analysis of the production of a Standard Model Higgs boson in association with up to three jets. We consider the gluon fusion channel using an effective theory in the large top-quark mass limit. Higgs boson production in gluon fusion constitutes an irreducible background to the vector boson fusion (VBF) process; hence the precise knowledge of its characteristics is a prerequisite for any measurement in the VBF channel. The calculation is carried out at next-to-leading order (NLO) in QCD in a fully automated way by combining the two programs GoS AM and SHERPA. We present numerical results for a large variety of observables for both standard cuts and VBF selection cuts.

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Search for resonant and nonresonant Higgs boson pair production in the $ \mathrm{b}\overline{\mathrm{b}}\mathit{\ell \nu \ell \nu } $ final state in proton-proton collisions at $ \sqrt{s}=13 $ TeV

Searches for resonant and nonresonant pair-produced Higgs bosons (HH) decaying respectively into ℓνℓν, through either W or Z bosons, and $ \mathrm{b}\overline{\mathrm{b}} $ are presented. The analyses are based on a sample of proton-proton collisions at $ \sqrt{s}=13 $ TeV, collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 fb$^{−1}$. Data and predictions from the standard model are in agreement within uncertainties. For the standard model HH hypothesis, the data exclude at 95% confidence level a product of the production cross section and branching fraction larger than 72 fb, corresponding to 79 times the standard model prediction. Constraints are placed on different scenarios considering anomalous couplings, which could affect the rate and kinematics of HH production. Upper limits at 95% confidence level are set on the production cross section of narrow-width spin-0 and spin-2 particles decaying to Higgs boson pairs, the latter produced with minimal gravity-like coupling.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Type-II seesaw scalar triplet model at a 100 TeV pp collider: discovery and higgs portal coupling determination

We investigate the collider phenomenology of the scalar triplet particles in the Type-II seesaw model at a 100 TeV pp collider. Depending on triplet vacuum expectation value v Δ , the dominant discovery channels could be H ++ H -- and H ±± H ∓ . We find the H ±± H ∓ → W ± W ± hW ∓ /ℓ ± ℓ ± hW ∓ channels are promising for both model discovery at relatively large v Δ and determination of the Higgs portal couplings λ 4 and λ 5 . We also find that these two channels are complementary to indirect determination of λ 4 from future precise measurements on h → γγ decay rate. Together with pair production of the doubly-charged Higgs subsequently decaying into same-sign di-leptons, the H ±± H ∓ channels have the potential to cover a significant portion of the parameter space of the Type-II seesaw complex scalar triplet model.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Search for flavor-changing neutral current interactions of the top quark and the Higgs boson decaying to a bottom quark-antiquark pair at $ \sqrt{s} $ = 13 TeV

A search for flavor-changing neutral current interactions of the top quark (t) and the Higgs boson (H) is presented. The search is based on a data sample corresponding to an integrated luminosity of 137 fb-1 recorded by the CMS experiment at the LHC in proton-proton collisions at √s = 13 TeV. Events containing exactly one lepton (muon or electron) and at least three jets, among which at least two are identified as originating from the hadronization of a bottom quark, are analyzed. A set of deep neural networks is used for kinematic event reconstruction, while boosted decision trees distinguish the signal from the background events. No significant excess over the background predictions is observed, and upper limits on the signal production cross sections are extracted. These limits are interpreted in terms of top quark decay branching fractions (B) to the Higgs boson and an up (u) or a charm quark (c). Assuming one nonvanishing extra coupling at a time, the observed (expected) upper limits at 95% confidence level are B(t → Hu) < 0.079 (0.11)% and B(t → Hc) < 0.094 (0.086)%.

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