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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 as the signal. We make an extensive study of all possible 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. Received: 5 July 2002 / Published online: 30 August 2002  相似文献   

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Exclusive double diffractive (EDD) Higgs boson production is analyzed in the framework of the Regge-eikonal approach. Total and differential cross-sections for the process are calculated. Experimental possibilities to find the Higgs boson at LHC are discussed.Received: 5 November 2003, Revised: 16 April 2004, Published online: 30 July 2004 Correspondence to and send offprint requests to: R.A. Ryutin  相似文献   

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One of the future goals of the LHC is to precisely measure the properties of the Higgs boson. The associated production of a Higgs boson and top quark pair is a promising process to investigate the related Yukawa interaction and the properties of the Higgs. Compared with the pure scalar sector in the Standard Model, the Higgs sector contains both scalars and pseudoscalars in many new physics models, which makes the ttH interaction more complex and provides a variety of phenomena. To investigate the ttH interaction and the properties of the Higgs, we study the top quark spin correlation observables at the LHC.  相似文献   

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Unification at MGUT∼3×1016 GeVMGUT3×1016 GeV of the three Standard Model (SM) gauge couplings can be achieved by postulating the existence of a pair of vectorlike fermions carrying SM charges and masses of order 300 GeV–1 TeV. The presence of these fermions significantly modifies the vacuum stability and perturbativity bounds on the mass of the SM Higgs boson. The new vacuum stability bound in this extended SM is estimated to be 117 GeV, to be compared with the SM prediction of about 128 GeV. An upper bound of 190 GeV is obtained based on perturbativity arguments. The impact on these predictions of type I seesaw physics is also discussed. The discovery of a relatively ‘light’ Higgs boson with mass ∼117 GeV117 GeV could signal the presence of new vectorlike fermions within reach of the LHC.  相似文献   

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《Comptes Rendus Physique》2015,16(10):994-1002
After the Higgs boson has been discovered, the Standard Model of particle physics became a confirmed theory, potentially valid up to the Planck scale and allowing one to trace the evolution of the Universe from the inflationary stage till the present days. We discuss the relation between the results from the LHC and the inflationary cosmology. We overview the Higgs inflation, and its relation to the possible metastability of the electroweak vacuum. A short overview of the bounds on the metastability of the electroweak vacuum in the models with inflation not related to the Higgs boson is presented.  相似文献   

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Considering the process pp → VH+X(V = W or Z) is a significant channel for searching for a light Higgs boson,we calculate the contributions of the littlest Higgs model with T-parity(called LHT model) to its production cross section.We find that,in most of the parameter space,the value of the relative correction parameter R is very small.However,with reasonable values of the free parameters,its value can be significantly larger.  相似文献   

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《Nuclear Physics B》1998,511(3):523-549
We examine the contributions of soft gluons to the Higgs production cross section at the LHC in the Standard Model and its minimal supersymmetric extension. The soft gluon radiation effects of this reaction share many features with the Drell-Yan process, but arise at lowest order from a purely gluonic initial state. We provide an extension of the conventional soft gluon resummation formalism to include a new class of contributions which we argue to be universal, and resum these and the usual Sudakov effects to all orders. The effect of these new terms is striking: only if they are included, does the expansion of the resummed cross section to next-to-leading order reproduce the exact result to within a few percent for the full range of Higgs boson masses. We use our resummed cross section to derive next-to-next-to-leading order results, and their scale dependence. Moreover, we demonstrate the importance of including the novel contributions in the resummed Drell-Yan process.  相似文献   

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刘伟  岳崇兴  苏雪松  王永智 《中国物理 C》2010,34(10):1565-1569
Considering the process pp→VH +X(V = W or Z) is a significant channel for searching for a light Higgs boson, we calculate the contributions of the littlest Higgs model with T-parity (called LHT model) to its production cross section. We find that, in most of the parameter space, the value of the relative correction parameter R is very small. However, with reasonable values of the free parameters, its value can be significantly larger.  相似文献   

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The discovery of the Higgs boson(s) is the major goal of the LHC which will start taking data in 2008. In this work a data driven extraction of the background and statistical signal significance in the H→ZZ→4ℓ decay channel is presented. The background for Higgs masses as low as 130 GeV can be extracted with an error of 20%, using a sideband measurement from a single 30 fb-1 experiment. The predicted background distribution is best described by a double asymmetric Gaussian. An analytic formula is introduced which provides an accurate p-value that a Higgs discovery claim is consistent with a background fluctuation. The formula can be used in a single real measurement at LHC using as input the measured background and the profile likelihood asymmetric errors of this measurement. The method presented here can be applied to the general case of extrapolating from a signal-free data region to a candidate signal region. This is the case of supersymmetry searches at the LHC. PACS  14.80.Bn; 06.20.Dk  相似文献   

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The Elementary Goldstone Higgs(EGH) model is a perturbative extension of the standard model(SM),which identifies the EGH boson as the observed Higgs boson. In this paper, we study pair production of the EGH boson via gluon fusion at the LHC and find that the resonant contribution of the heavy scalar is very small and the SM-like triangle diagram contribution is strongly suppressed. The total production cross section mainly comes from the box diagram contribution and its value can be significantly enhanced with respect to the SM prediction.  相似文献   

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The next-to-minimal supersymmetric standard model(NMSSM)more naturally accommodates a Higgs boson with a mass of approximately 125 Ge V than the minimal supersymmetric standard model(MSSM).In this work,we assume that the next-to-lightest CP-even Higgs boson h2 is the SM-like Higgs boson h,whereas the lightest CP-even Higgs boson h_(1)is dominantly singlet-like.We discuss the h_1h_1,h_2h_2,and h_1h_(2)pair production processes via gluon-gluon fusion at the LHC for an collision energy of 14 Te V,and we consider the cases in which one Higgsboson decays to bˉb and the other decays toγγorτ~+τ~-.We find that,for m_(h1) 62 GeV,the cross section of the gg→h_1h_(1)process is relatively large and maximally reaches 5400 fb,and the production rate of the h_1h_1→bˉbτ~+τ~-final state can reach 1500 fb,which make the detection of this final state possible for future searches of an integrated luminosity of 300 and 3000 fb~(-1).This is mainly due to the contributions from the resonant production process pp→h_2→h_1h_(1)and the relatively large branching ratio of h_1→bb and h_1→τ~+τ~-.The cross sections of the pp→h_2h_2and pp→h_1h_2 production processes maximally reach 28 fb and 133 fb,respectively.  相似文献   

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In this paper, we study the observability of an invisible Higgs boson at Fermilab Tevatron and CERN LHC through the production channel qq̄→ZH→ℓ+-+P/T, where/PT is reconstructed from the ℓ+- with ℓ=e or μ. A new strategy is proposed to eliminate the largest irreducible background, namely qq̄→Z(→ℓ+-)Z(→νν̄). This strategy utilizes the precise measurements of qq̄→Z(→ℓ+-)Z(→ℓ+-). For mH=120 GeV and with luminosity 30 fb-1 at Tevatron, a 5σ observation of the invisible Higgs boson is possible. For mH=114∼140 GeV with only 10 fb-1 luminosity at LHC, a discovery signal over 5σ can be achieved. PACS 14.80.Cp  相似文献   

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《Comptes Rendus Physique》2015,16(4):394-406
With the discovery of the Higgs boson by the LHC in 2012, a new era started in which we have direct experimental information on the physics behind the breaking of the electroweak (EW) symmetry. This breaking plays a fundamental role in our understanding of particle physics and sits at the high-energy frontier beyond which we expect new physics that supersedes the Standard Model (SM). In this review we summarize what we have learned so far from LHC data in this respect. In the absence of new particles having been discovered, we discuss how the scrutiny of the properties of the Higgs boson (in search for deviations from SM expectations) is crucial as it can point the way for physics beyond the SM. We also emphasize how the value of the Higgs mass could have far-reaching implications for the stability of the EW vacuum if there is no new physics up to extremely large energies.  相似文献   

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《Physics letters. [Part B]》1999,459(4):607-614
The hadronic tau decay channel offers by far the best signature for heavy charged Higgs boson search at the LHC in the large tanβ region. By exploiting the distinct polarization of the tau and its large transverse mass, along with the accompanying missing–pT, one can probe for a charged Higgs boson up to a mass of about 600 GeV in an essentially background-free environment. The transverse mass distribution of the tau jet also provides a fairly unambiguous estimate of the charged Higgs boson mass.  相似文献   

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In order to solve the hierarchy problem, several extra-dimensional models have received considerable attention. We have considered a process where a Higgs boson is produced in association with a KK-graviton (G KK) at the LHC. At the leading order, this process occurs through the gluon fusion mechanism gghG KK via a quark loop. We compute the cross section and examine some features of this process in the ADD model. We find that the quark in the loop does not decouple in the large quark-mass limit just as in the case of ggh process. We compute the cross section of this process for the case of the RS model also. We examine the feasibility of this process being observed at the LHC.  相似文献   

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