We investigate how adding a scalar resonance of a mass 125 GeV affects the low-energy data support for the top-BESS model as well as its low-energy free parameter limits. The top-BESS model is an effective Lagrangian, a modification of the well-known BESS model, with an ambition to describe phenomenology of the lowest bound states of strongly-interacting theories beyond the Standard model. In particular, the SU(2)_{L+R} vector resonance triplet of hypothetical bound states is a centerpiece of BESS-like effective models. The top-BESS model assumes that the triplet couples directly to the third quark generation only. This assumption reflects a possible special standing of the third quark generation, and the top quark in particular, in physics of electroweak symmetry breaking. Our findings suggest that the 125 GeV scalar extension of the top-BESS model results in a higher statistical support for the model. The best-fit values of the model's free parameters are consistent with the top quark having a higher degree of compositeness than the bottom quark.
This is a brief outline of the top-BESS model and its properties. The top-BESS model is the higgsless effective description of the strong electroweak symmetry breaking with a single new SU(2)_L+R triplet vector resonance. In contrast with the universality of the fermion interactions of the BESS model, the top-BESS vector resonance couples directly to the third quark generation only. The complete formulation of the model along with its phenomenology can be found in arXiv:1107.0570.
We study top production at Tevatron collider in the extended BESS model, which is an effective lagrangian parametrization of a dynamical symmetry breaking of the electroweak symmetry. The existence of a colored octet of gauge vector bosons can increase top production at a rate still consistent with recent experimental data and lead to distorsions in the transverse momentum spectrum of the top.
We investigate the reaction e^+ e^- \to W^+ W^-, W^- \to l^- \bar{nu} in a strong coupling scenario as implemented in the BESS model. Energy and angle spectra of the secondary lepton are calculated and compared with the predictions of the Standard Model. These spectra provide a determination of the fraction f_0 of longitudinally polarized W's, and the backward fraction of secondary leptons, f_{back}. Assuming BESS parameters allowed by present data, we give numerical estimates of the effects to be expected at an e^+e^- collider of energy \sqrt{s} = 500- 800 GeV.
We introduce the top-BESS model which is the effective description of the strong electroweak symmetry breaking with a single new SU(2)_L+R triplet vector resonance. The model is a modification of the BESS model in the fermion sector. The triplet couples to the third generation of quarks only. This approach reflects a possible extraordinary role of the top quark in the mechanism of electroweak symmetry breaking. The low-energy limits on the model parameters found provide hope for finding sizable signals in the LHC Drell-Yan processes as well as in the s-channel production processes at the ILC. …
We explore the ΔL=2 same-sign dilepton signal from top-quark decay via a Majorana neutrino at the LHC in the top anti-top pair production samples. The signature is same-sign dilepton plus multi-jets with no significant missing energy. The most optimistic region lies where the Majorana neutrino mass is between 15-65 GeV. For 300 fb^-1 integrated luminosity, it is possible to probe S_{ij}, the effective mixing parameter, to order of 10^-5.
Imposing the constraint that the Standard Model effective Higgs potential should have two degenerate minima ( vacua), one of which should be - order of magnitudewise - at the Planck scale, leads to the top mass being 173 +/- 5 GeV and the Higgs mass 135 +/- 9 GeV. This requirement of the degeneracy of different phases is a special case of what we call the multiple point criticality principle. In the present work we use the Standard Model all the way to the Planck scale, and do not introduce supersymmetry or any extension of the Standard Model gauge group. A possible model to explain the multip…
We discuss a model which involves the top quark condensation and the walking technicolor. We focus on the scalar boson in such a model from the viewpoint of the observed scalar boson at the LHC.
The latest LHC data suggest an intriguing excess at $m_{γγ} = 750$ GeV which apparently requires an explanation from the beyond standard model physics. In this note we explore the possibility for this signal to arise from a top-pion in the Top Triangle Moose model which can be viewed as a dimensional-deconstruction version of the top-color assisted technicolor model. We demonstrate that the observed excess can be accommodated by and has important implications for this interesting model.
We study the implications for bounds on the top quark pole mass m_t in models with low scale supersymmetry following the discovery of the Standard Model-like Higgs boson. In the minimal supersymmetric standard model, we find that m_t >= 164 GeV, if the light CP even Higgs boson mass m_h = 125 +-2 GeV. We also explore the top quark and Higgs boson masses in two classes of supersymmetric SO(10) models with t-b-tau Yukawa coupling unification at M_GUT. In particular, assuming SO(10) compatible non-universal gaugino masses, setting m_h = 125 GeV and requiring 5% or better Yukawa unification, we ob…
The scalar top discovery potential has been studied for the TESLA project with a full-statistics background simulation at sqrt(s)=500 GeV and L=500 fb-1. The beam polarization is very important to measure the scalar top mixing angle and to determine its mass. The latest estimation of the beam polarization parameters is applied. This study includes e+ polarization, which improves the sensitivity. For a 180 GeV scalar top at minimum production cross section, we obtain Delta(m)=0.8 GeV and Delta(cos(Theta))=0.008 in the neutralino channel, and Delta(m)=0.5 GeV and Delta(cos(Theta))=0.004 in the c…
The Composite Particles Model (CPM) is characterized by composite Higgs, composite top quark, cancelation of the scalar leading quadratic divergences, and a particular ground state such that top anti-top channel is neither attractive or repulsive at tree level at the Z pole mass. The radiatively generated scalar mass in 2D is m_H=\sqrt((6m_t^2 -M_Z^2-2M_w^2)/3(1+π/k))= 113 GeV/c^2,143 GeV/c^2,...,230 GeV/c^2 for k = 1,2,...\infty. As first proposed by Nambu in the simplest models with dynamical mass generation and fermion condensate in 4D, one expects the Higgs mass on the order of twice the h…
In this paper, we interpret the 750 GeV diphoton excess in the Zee-Babu extension of the two-Higgs-doublet model by introducing a top partner ($T$)/bottom partner ($B$). In the alignment limit, the 750 GeV resonance is identified as the heavy CP-even Higgs boson ($H$), which can be sizably produced via the QCD process $pp \to T\bar{T}$ or $pp \to B\bar{B}$ followed by the decay $T\to Ht$ or $B \to Hb$. The diphoton decay rate of $H$ is greatly enhanced by the charged singlet scalars predicted in the Zee-Babu extension and the total width of $H$ can be as large as 7 GeV. Under the current LHC c…
We estimate the top quark, lightest sparticle (LSP) and scalar higgs masses within a supersymmetric grand unified framework in which $\tanβ\simeq m_t/m_b$ and the electroweak symmetry is radiatively broken. The requirement that the calculated $b$ quark mass lie close to its measured value, together with the cosmological constraint $Ω_{LSP} \approx 1$, fixes the top quark mass to be $m_t(m_t) \approx 170 \pm 15\ GeV$. The LSP (of bino purity $\stackrel{_>}{_\sim} 98\%)$ has mass $\sim 200 - 350\ GeV$. In the scalar higgs sector the CP-odd scalar mass $m_A \stackrel{_<}{_\sim} 220\ GeV$. With $m…
We consider the effect of gluon radiation on the energy of top/antitop quarks and on the anticollinearity of top-antitop quark pairs produced in $e^+e^-$ annihilation. Our results are presented in terms of the $E_q$-dependence of the $t\bar tg$ cross section and the dependence on the cosine of the opening angle $θ_{12}$ between top and antitop for a center of mass energy of $\sqrt{q^2}=500 GeV$. We then go on to determine mean values for the top quark's energy as well as its longitudinal and transverse projections, and for the deviation of $\sinθ_{12}$ and $\cosθ_{12}$ from the anticollinearit…
The radiatively generated Higgs mass is obtained by requiring that leading "divergences" are cancelled in both 2D and 4D. This predicts one or more viable modes; the k=1 mode mass is m_H\cong2/3 m_t\cong115GeV whereas the k=2 mode is m_H\cong143GeV. These findings are interpreted within the Composite Particles Model (CPM), [Popovic 2002, 2010], with the massive top quark being a composite structure composed of 3 fundamental O quarks (O\bar{O}O) and the massive Higgs scalar being a color-neutral meson like structure composed of 2 fundamental O quarks (\bar{O}O). The CPM predicts that the Z mass…
The scalar top discovery potential has been studied with a full-statistics background simulation at sqrt(s)=500 GeV and L = 500 fb-1 for the TESLA project. The beam polarization is very important to measure the scalar top mixing angle and to determine its mass. The latest estimation of the beam polarization parameters is applied. This study includes e+ polarization, which improves the sensitivity. For a 180 GeV scalar top at minimum production cross section, we obtain delta(m) = 0.8 GeV and delta(cosT) = 0.008 in the neutralino decay channel, and delta(m) = 0.5 GeV and delta(cosT) = 0.004 in t…
In the standard model, a lower bound to the Higgs mass (for a given top quark mass) exists if one requires that the standard model vacuum be stable. This bound is calculated as precisely as possible, including the most recent values of the gauge couplings, corrected two-loop beta functions and radiative corrections to the Higgs and top masses. In addition to being somewhat more precise, this work differs from previous calculations in that the bounds are given in terms of the poles of the Higgs and top quark propagators, rather than ''the MS-bar top quark mass''. This difference can be as large…
I address: (1) dynamical, likely local Higgs mass generation as resolution to the 4D hierarchy and vacuum energy problems, (2) possibility that top condensation may be explained by an interplay among the gluon and scalar sectors, (3) the Higgs Mass Zero Crossing (HMZC) scale, most likely equal to Λ_EWSB, in accord with standard cosmology or classic inflation, and (4) two preferred Higgs regions centered at 116.5 GeV and 140.5 GeV with related high energy models. I show that SM in 2D could simultaneously satisfy (a) complete radiative generation of the Higgs mass via top loop and (b) cancelatio…
We propose to interpret the 750 GeV diphoton excess in a typical topflavor seesaw model. The new resonance X can be identified as a CP-even scalar emerging from a certain bi-doublet Higgs field. Such a scalar can couple to charged scalars, fermions as well as heavy gauge bosons predicted by the model, and consequently all of the particles contribute to the diphoton decay mode of the X. Numerical analysis indicates that the model can predict the central value of the diphoton excess without contradicting any constraints from 8 TeV LHC, and among the constraints, the tightest one comes from the Z…
Pair-production of heavy top quarks at the Tevatron Collider is significantly enhanced by the color--octet technipion, $η_T$, occurring in multiscale models of walking technicolor. We discuss $\bar tt$ rates for $m_t = 170$ GeV and $M_{η_T} = 400-500$ GeV. Multiscale models also have color--octet technirho states in the mass range 200-600 GeV that appear as resonances in dijet production and technipion pair--production.
Within one loop approximation, the renormalization group analysis of the Higgs boson mass is performed with an initial condition induced by $m_{_H}=\sqrt{2}m_{_W}$ which is presented in the new scheme of our noncommutative differential geometry for the reconstruction of the standard model. This initial condition holds at energy derived from $g^2=(5/3)g'^2$ with the running SU(2)$_{_L}$ and U(1)$_{_Y}$ gauge coupling constants. $\sin^2θ_{_W}=3/8$ is obtained under same conditions. However, contrary to ${\rm SU(5)}$ GUT without supersymmetry, the grand unification of coupling constant is not rea…
Searching for the top squark (stop) is a key task to test the naturalness of SUSY. Different from stop pair production, single stop production relies on its electroweak properties and can provide some unique signatures. Following the single production process $pp \to \tilde t_1 \tildeχ^-_1 \to t \tildeχ^0_1 \tildeχ^-_1$, the top quark has two decay channels: leptonic channel and hadronic channel. In this paper, we probe the observability of these two channels in a simplified MSSM scenario. We find that, at the 27 TeV LHC with the integrated luminosity of ${\cal L} = 15~\text{ab}^{-1}$, $m_{\ti…
This is an addendum to the paper of the above title published in Physics Letters B317, 159 (1993). In that paper, I found the lower bound to the Higgs mass as a function of the top quark mass one obtains by requiring that the standard model vacuum be stable. It included all higher order corrections to two-loops, precise definitions of the Higgs and top masses, etc. Unfortunately, the results were given for top quark masses between 120 and 160 GeV. In this addendum, I give the results for masses between 160 and 190 GeV. The main result, using a value of 0.117 for the strong coupling at the Z-ma…
A global analysis is performed using the latest data from LEP and SLC. Constraints on the electroweak universal parameters ($S,T,U$) and on the masses of the top quark and Higgs boson within the Standard Model (SM) are investigated. The uncertainties due to the QCD and QED effective couplings, $α_s(\mz)$ and $\barα(\mmz)$, are examined in detail. Even though the mean value of $S$ is increased to be consistent with zero, the naive Technicolor models are still disfavored due to its reduced error. Within the SM, we find the 90\,\%CL constraints; $133\gev<m_t<190\gev$ and $10\gev<\mh<440\gev$ for …
Crude estimates are made of the branching ratios and pair production cross-section for our previously proposed bound state S of six top and six antitop quarks identified with the diphoton excess recently observed in ATLAS and CMS. We estimate the pair production cross section to be approximately 12 times that for fourth family quarks. Hence we predict $σ(pp \rightarrow SS + anything) \approx 2$ pb at 13 TeV and an increase by a factor 10 over the cross section at 8 TeV. Crude estimates of the main branching ratios relative to the diphoton decay give $Γ(S\rightarrow γ+γ) \propto 1$, $Γ(S\righta…
A hint of a new resonance at a mass of 750\,GeV has been observed in the diphoton channel of LHC Run 2 at $\sqrt{s}=13$ TeV. The signal rate is too large to interpret it as a new Higgs boson in the context of weakly-coupled renormalizable models. One way is to reduce its total decay rate, which is possible if the CP-even heavy Higgs boson $H^0$ in the aligned two Higgs doublet model becomes top-phobic. To ensure sufficient gluon fusion production, we introduce vector-like quarks (VLQ). The Higgs precision data as well as the exclusion limits from no excesses in other 8 TeV LHC searches of $Zγ$…
A model for composite electroweak bosons is re-examined to establish approximate ranges for the initial predictions of the top and Higgs masses. Higher order corrections to this $4$-fermion theory at a high mass scale where the theory is matched to the Standard Model have little effect, as do wide variations in this scale. However, including all one loop evolution and defining the masses self-consistently, at their respective poles, moves the top mass upward by some $10$ GeV to near $175$ GeV and the Higgs mass down by a similar amount to near $125$ GeV.
The scalar interaction term of the top mode standard model can be generated by a gauge theory. It is emphasized that in this approach generalization to family space directly yields a heavy top quark while leaving all other quarks massless. By generating the new interaction from gauge extension to custodial $SU(2)$, the standard model bound $m_{top} \stackrel{<}{\sim} 200 GeV$ is pushed to $m_{top} \stackrel{<}{\sim} 270 GeV$, thereby significantly reducing the amount of finetuning required to match this number.
We discuss the modified top quark condensation model proposed in \cite{VZ2015}. This construction was inspired by the top - seesaw scenario, in which the extra heavy fermion $χ$ is added that may be paired with the top quark. Besides, this model incorporates the ideas of the Little Higgs scenario, in which the $125$ GeV scalar particle appears as a Pseudo - Goldstone boson. This model admits (in addition to the $125$ GeV scalar boson $H$) the heavier scalar excitation $H^\prime$. We consider the region of parameters, where its mass is $M_{H^\prime} \sim 1$ TeV, the width of $H^\prime$ is $Γ_{H…
In this paper, we study the single top and Higgs associated production $\rm e^- p\rightarrow ν_e \bar{t} \rightarrow ν_e h \bar{q}(h\rightarrow b\bar{b})$ in the top-Higgs FCNC couplings at the LHeC with the electron beam energy of $E_{e}$ = 60 GeV and $E_{e}$ = 120 GeV, combination of a 7 TeV and 50 TeV proton beam. With the possibility of e-beam polarization ($p_{e}$ = 0, $\pm0.6$), we distinct the Cut-based method and the Multivariate Analysis (MVA) based method, and compare with the current experimental and theoretical limits. It is shown that the branching ratio Br $\rm(t\to uh)$ can be p…
The ATLAS and CMS experiments observed a particle at the LHC with a mass $\approx 126$ GeV, which is compatible with the Higgs boson of the Standard Model. A crucial question is, if for such a Higgs mass value, one could extrapolate the model up to high scales while keeping the minimum of the scalar potential that breaks the electroweak symmetry stable. Vacuum stability requires indeed the Higgs boson mass to be $M_H \gsim 129 \pm 1$ GeV, but the precise value depends critically on the input top quark pole mass which is usually taken to be the one measured at the Tevatron, $m_t^{\rm exp}=173.2…
We report on the feasibility of the direct measurement of the top Yukawa coupling g_t at the International Linear Collider (ILC) during its first phase of operation with a center-of-mass energy of 500 GeV. The signal and background models incorporate the non-relativistic QCD corrections which enhance the production cross section near the t-tbar threshold. The e+e- -> t tbar H signal is reconstructed in the 6-jet + lepton and the 8-jet modes. The results from the two channels are combined. The background processes considered are e+e- -> t bbar W- / tbar b W+ (which includes e+e- -> t tbar), e+e…
Aspects of top quark physics can be studied at a future Circular Electron-Positron Collider (CEPC). In particular, Flavor-Changing Neutral Current interactions (FCNC) of the top quark can be studied even with a center-of-mass energy from $\sqrt{s}\gtrsim m_t$ to $\sqrt{s}=240$ GeV, through the production a single top quark in association with a charm quark, which can arise in several scenarios of new physics. We explore here this signal within the Left-Right Mirror Model, which is a Left-Right model that includes mirror fermions; this model is motivated as a possible solution to the strong CP …
Precise predictions for an $e^+e^-\rightarrow t\bar{t}$ cross-section are presented in the energy region from 400 GeV to 800 GeV. Cross-sections are estimated including the beam-polarization effects with full $\mathcal{O}(α)$, and also with the effects of the initial-state photon emission. A radiator technique is used for the initial-state photon emission up to two-loop orders. In this investigation, a weak correction is defined as the full electroweak corrections without the initial-state photonic corrections. As a result, it is determined that the total cross-section of a top quark pair-prod…
The scalar top discovery potential has been studied with a full-statistics background simulation for sqrt(s) = 500 GeV and L = 500 fb-1. The simulation is based on a fast and realistic simulation of a TESLA detector. The large simulated data sample allowed the application of an Iterative Discriminant Analysis (IDA) which led to a significantly higher sensitivity than in previous studies. The effects of beam polarization on signal efficiency and individual background channels are studied using separate optimization with the IDA for both polarization states. The beam polarization is very importa…
The fine-tuning principles are analyzed in search for predictions of top-quark and Higgs-boson masses. The modification of Veltman condition based on the compensation between fermion and boson vacuum energies within the Standard Model multiplets is proposed. It is supplied with the stability under rescaling and with the requirement of minimum for the physical v. e. v. for the Higgs field (zero anomalous dimension). Their joint solution for top-quark and Higgs-boson couplings exists for the cutoff $Λ\approx 2.3 \cdot 10^{13}\,GeV$ that yields the low-energy values $m_t = 151 \pm 4\,GeV; m_H = 1…
Precise predictions for an $e^+e^-\rightarrow t\bar{t}$ cross section are presented at an energy region from 400 GeV to 800 GeV. Cross sections are estimated including the beam-polarization effects with full $\mathcal{O}(α)$, and also with effects of the initial-state photon emission. A radiator technique is used for the initial-state photon emission up to two-loop order. A weak correction is defined as the full electroweak corrections without the initial-state photonic corrections. As a result, it is obtained that the total cross section of a top quark pair-production receives the weak correc…
The composite Higgs models based on the top seesaw mechanism commonly possess an enhanced approximate chiral symmetry, which is spontaneously broken to produce the Higgs field as the pseudo-Nambu-Goldstone bosons. The minimal model with only one extra vector-like singlet quark that mixes with the top quark can naturally give rise to a 126 GeV Higgs boson. However, without having a custodial symmetry it suffers from the weak-isospin violation constraint, which pushes the chiral symmetry breaking scale above a few TeV, causing a substantial fine-tuning for the weak scale. We consider an extensio…
We advocate two Higgs doublet model without $Z_2$ symmetry, and focus on the extra top Yukawa couplings $ρ_{tt}$ and $ρ_{tc}$. We show that $A^0$ and $H^0$ bosons are still allowed at 300 GeV mass, where $cg \to tA^0$, $tH^0$ can lead to $tt\bar c$ same-sign top, or top-assisted di-Higgs $th^0h^0$ signatures, resp. As bonus material, we explore the constraint provided by current 4-top search, but advocate direct search for triple-top generated by $cg \to tH^0/A^0 \to tt\bar t$ for $H^0,\, A^0$ above $t\bar t$ threshold, and offer some insight on the mild but intriguing "excess" found by CMS in…
We constrain the masses of scalar-tops (stop) by analyzing the new precision Tevatron measurement of the W-boson mass and the LHC/Tevatron indications of a Higgs boson of mass 125.5+-1 GeV. Our study adopts Natural SUSY with low fine-tuning, which has multi-TeV first and second generation squarks and a light Higgsino mixing parameter mu=150 GeV. An effective Lagrangian calculation is made of mh to 3-loops using the H3m program with weak scale SUSY parameters obtained from RGE evolution from the GUT scale in the Natural SUSY scenario. The SUSY radiative corrections to the Higgs mass imply maxim…
The top/bottom seesaw model, which extends the top seesaw in order to accomodate a 125 GeV Higgs boson, predicts vector-like top/bottom partners and these partners can be bounded to form several neutral and charged singlet composite scalars by some new strong dynamics. In this letter, we use such a singlet scalar to interpret the 750 GeV diphoton reseanance. This singlet scalar is dominantly produced through the gluon fusion process induced by the partners and its diphoton decay is induced by both the partners and the charged singlet scalars. We show that this scenario can readily account for …
We consider a model of strong dynamics able to account for the origin of the electroweak symmetry breaking and heavy quark masses. The model is based on a technicolor sector, augmented with topcolor and top-seesaw mechanism to assist in the generation of heavy quark masses. The low energy effective theory is a particular three Higgs doublet model. The additional feature is the possibility of the existence of composite higher spin states beyond the scalars, which are shown to be essential in this model to provide extra contributions in the higgs decays into two photons. We provide a detailed st…
Recently, the CMS collaboration has reported a di-tau excess with a local significance of 2.6-3.1$σ$ where the invariant mass is $m_{ττ}=$95-100 GeV. This excess can be interpreted as a light scalar boson that couples to the third generation fermions, particularly top and $τ$. Based on the simplest model that can account for the CMS di-tau excess, we evaluate experimental sensitivities to the additional light resonance, using the results reported by the ATLAS collaboration. We see that a search for the top-quark associated production of the SM Higgs boson that decays into $τ\barτ$ sets a stron…
Top quark production in the process $e^+e^- \rightarrow t\bar{t}$ at a future linear electron positron collider with polarised beams is a powerful tool to determine indirectly the scale of new physics. The presented study, based on a detailed simulation of the ILD detector concept, assumes a centre-of-mass energy of $\roots=500$\,GeV and a luminosity of $\mathcal{L}=500\,\invfb$ equality shared between the incoming beam polarisations of $P_{e^{-,+}} =\pm0.8,\mp0.3$. Events are selected in which the top pair decays semi-leptonically. The study comprises the cross sections, the forward-backward …
We consider a model of dynamical electroweak symmetry breaking built on the idea of top-seesaw mechanism. The model features a fourth generation of vector-like QCD quarks responsible for the origin of the top-seesaw mechanism and leading to the natural explanation of the large splitting between the top and bottom quark masses. Motivated by the LHC data on the couplings of the Higgs boson, we include the entire third generation of Standard Model matter fields into the model. We determine the low energy effective theory and the resulting low energy spectrum of states, and constrain the model par…
The Standard Model of particle physics contains about two dozen parameters - such as particle masses - whose origins are still unknown and cannot be predicted, but whose values are constrained through their interactions. In particular, the masses of the top (t) quark (M_t) and W boson constrain the mass of the long-hypothesized, but thus far not observed, Higgs boson. A precise measurement of the top-quark mass can therefore point to where to look for the Higgs, and indeed whether the hypothesis of a SM Higgs is consistent with experimental data. Since top quarks are produced in pairs and deca…
Top polarization is an important probe of new physics that couples to the top sector, and which may be discovered at the 14 TeV LHC. Taking the example of the MSSM, we argue that top polarization measurements can put a constraint on the soft supersymmetry breaking parameter A_t. In light of the recent discovery of a Higgs-like boson of mass ~125 GeV, a large A_t is a prediction of many supersymmetric models. To this end, we develop a *detector level* analysis methodology for extracting polarization information from hadronic tops using boosted jet substructure. We show that with 100 fb^(-1) of …
Top partners from a new strong sector can be discovered soon, at the 8 TeV LHC, by analyzing their single production, which exhibits a large enhancement in the cross section compared to the analogous productions of bottom partners and exotic quarks. We analyze the subsequent decay of the top partners into a 125 GeV Higgs. This channel proves to be very promising for both the discovery of top partners and a test of the Higgs sector. For a reference value $λ_{\tilde{T}}=3$ of the Higgs coupling to the top partner, we could have a discovery (observation) at the 8 TeV LHC, with 30 fb$^{-1}$, for t…
If the Standard Model is valid up to scales near the Planck mass, and if the cosmological constant and Higgs mass parameters scan on a landscape of vacua, it is well known that the observed orders of magnitude of these quantities can be understood from environmental selection for large-scale structure and atoms. If in addition the Higgs quartic coupling scans, with a probability distribution peaked at low values, environmental selection for a phase having a scale of electroweak symmetry breaking much less than the Planck scale leads to a most probable Higgs mass of 106 GeV. While fluctuations …
We utilize the recent LHC-13 TeV data to study the lower mass bound on top-squark (stop) in natural supersymmetry. We recast the LHC sparticle inclusive search of $(\ge 1){\rm jets} + E^{miss}_T$ with $α_T$ variable, the direct stop pair search (1-lepton channel and all-hadronic channel) and the monojet analyses. We find that these searches are complementary depending on stop and higgsino masses: for a heavy stop the all-hadronic stop pair search provides the strongest bound, for an intermediate stop the inclusive SUSY analysis with $α_T$ variable is most efficient, while for a compressed stop…
We explore the implications of 7 TeV LHC searches for a scenario in which one of the stops is the next-to lightest supersymmetric particle (NLSP). The NLSP stop (\tilde{t}_1) is assumed to decay exclusively into neutralino and charm quark. We consider processes where the stops are pair produced together with a hard QCD jet. We also consider stop quarks from gluino decays, \tilde{g}\to t\tilde{t}_1^\ast+\bar{t}\tilde{t}_1. We show that the monojet ATLAS and CMS searches corresponding to 1 fb^{-1} of integrated luminosity are sensitive to stop masses of up to 160 GeV, with the 20% neutralino-sto…
The determination of the Yukawa coupling of the top quark to the Higgs boson is one of the most important measurements that a future e^+e^- linear collider could provide. For a Higgs boson of mass greater than 350 GeV, this coupling can be determined using the Higgs resonant contribution to t \bar t production from W^+ W^- fusion at TeV energies. We have made a careful evaluation of the significance with which the signal of a Higgs decaying to t \bar t pairs could be observed at future e^+ e^- linear colliders, with center of mass energies close to 1 TeV and an integrated luminosity of 1 ab^{-…
We consider six dimensional gauge models compactified on the orbifold T^2/Z_N (N=2,3,4,6) such that the Standard Model (SM) Higgs doublet arises from the extra-dimensional components of the gauge field. For Λ\leq 10^{19} GeV, where Λdenotes the compactification scale, we obtain 114.4 GeV \leq m_H \leq 164 GeV for the SM Higgs boson mass. We also consider gauge-Higgs-top and gauge-Higgs-bottom Yukawa unification which respectively yield m_H = 131^{+4}_{-5} GeV and m_H = 150^{+2}_{-2} GeV for a top quark pole mass M_t =170.9^{+1.8}_{-1.8} GeV. As a special case we recover the result m_H \leq 132…
