scholarly journals EFFECTS OF NONSTANDARD INTERACTIONS FOR THE ENERGY SPECTRUM OF SECONDARY LEPTONS IN $e^+ e^-\to t\bar t$

1999 ◽  
Vol 14 (08) ◽  
pp. 1261-1281 ◽  
Author(s):  
LONGIN BRZEZIŃSKI ◽  
BOHDAN GRZADKOWSKI ◽  
ZENRŌ HIOKI
Keyword(s):  
Energy Spectrum ◽  
Standard Model ◽  
Pair Production ◽  
Top Quark ◽  
High Energy ◽  
Parameter Determination ◽  
Beyond The Standard Model ◽  
Energy Correlation ◽  
Optimal Method ◽  
The Standard Model

The process of top-quark pair production followed by semileptonic decays at future high-energy e+ e- linear colliders is investigated as a possible test of physics beyond the Standard Model. Assuming the most general nonstandard forms for [Formula: see text], [Formula: see text] and Wtb couplings, the energy spectrum of the single lepton ℓ± and the energy correlation of ℓ+ and ℓ- emerging from the process [Formula: see text] are calculated. Expected precision of the nonstandard-parameter determination is estimated adopting the recently-proposed optimal method.

scholarly journals A CRITICAL LOOK AT PRECISION ELECTROWEAK DATA AT HIGH ENERGY—A HINT FOR PHYSICS BEYOND THE STANDARD MODEL?

1994 ◽  
Vol 09 (35) ◽  
pp. 3301-3312
Author(s):  
A. GURTU
Keyword(s):  
Standard Model ◽  
Pair Production ◽  
High Energy ◽  
Recent Measurement ◽  
Beyond The Standard Model ◽  
Full Data ◽  
Text Production ◽  
Basic Framework ◽  
The Standard Model ◽  
Precision Electroweak Data

High energy electroweak data, including the recent measurement of M top is analyzed within the basic framework of the standard model. While the experimentally measured value of [Formula: see text] implies a low value of M top , the rest of the data demands a much higher value. Estimates of M Higgs within the SM framework including and excluding this Rb measurement are given. Next this discrepancy is expressed in terms of a new parameter, [Formula: see text], the excess[Formula: see text] production compared to that expected from a SM fit. This parameter is determined to be (9.4 to 12.8) ± 5.0 MeV, implying an excess of over 10 000 [Formula: see text] events in each LEP experiment after the 1993 data is fully analyzed. The origin of these events could be non-minimal Higgs pair production which should be thoroughly searched for in the full data sample of ~2×106 events per LEP experiment. Unless this discrepancy eventually turns out to be a fluctuation one may be witnessing at LEP the advent of physics beyond the standard model.

scholarly journals Effective operator bases for beyond Standard Model scenarios: an EFT compendium for discoveries

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Upalaparna Banerjee ◽  
Joydeep Chakrabortty ◽  
Suraj Prakash ◽  
Shakeel Ur Rahaman ◽  
Michael Spannowsky
Keyword(s):  
Standard Model ◽  
High Energy ◽  
Beyond The Standard Model ◽  
Minimal Extension ◽  
Effective Operator ◽  
Abelian Gauge ◽  
Gauge Symmetries ◽  
Higher Dimensional ◽  
The Standard Model ◽  
Mass Dimension

Abstract It is not only conceivable but likely that the spectrum of physics beyond the Standard Model (SM) is non-degenerate. The lightest non-SM particle may reside close enough to the electroweak scale that it can be kinematically probed at high-energy experiments and on account of this, it must be included as an infrared (IR) degree of freedom (DOF) along with the SM ones. The rest of the non-SM particles are heavy enough to be directly experimentally inaccessible and can be integrated out. Now, to capture the effects of the complete theory, one must take into account the higher dimensional operators constituted of the SM DOFs and the minimal extension. This construction, BSMEFT, is in the same spirit as SMEFT but now with extra IR DOFs. Constructing a BSMEFT is in general the first step after establishing experimental evidence for a new particle. We have investigated three different scenarios where the SM is extended by additional (i) uncolored, (ii) colored particles, and (iii) abelian gauge symmetries. For each such scenario, we have included the most-anticipated and phenomenologically motivated models to demonstrate the concept of BSMEFT. In this paper, we have provided the full EFT Lagrangian for each such model up to mass dimension 6. We have also identified the CP, baryon (B), and lepton (L) number violating effective operators.

scholarly journals A global view of the off-shell Higgs portal

2020 ◽  
Vol 8 (2) ◽  
Author(s):  
Maximilian Ruhdorfer ◽  
Ennio Salvioni ◽  
Andreas Weiler
Keyword(s):  
Dark Matter ◽  
Standard Model ◽  
Vector Boson ◽  
Effective Interaction ◽  
Goldstone Boson ◽  
High Energy ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Higgs Portal ◽  
First Time

We study for the first time the collider reach on the derivative Higgs portal, the leading effective interaction that couples a pseudo Nambu-Goldstone boson (pNGB) scalar Dark Matter to the Standard Model. We focus on Dark Matter pair production through an off-shell Higgs boson, which is analyzed in the vector boson fusion channel. A variety of future high-energy lepton colliders as well as hadron colliders are considered, including CLIC, a muon collider, the High-Luminosity and High-Energy versions of the LHC, and FCC-hh. Implications on the parameter space of pNGB Dark Matter are discussed. In addition, we give improved and extended results for the collider reach on the marginal Higgs portal, under the assumption that the new scalars escape the detector, as motivated by a variety of beyond the Standard Model scenarios.

SEARCHES FOR NEW PHYSICS AT HIGH ENERGY COLLIDERS

2005 ◽  
Vol 20 (22) ◽  
pp. 5164-5173 ◽  
Author(s):  
BEATE HEINEMANN
Keyword(s):  
Standard Model ◽  
Extra Dimensions ◽  
High Energy ◽  
New Physics ◽  
Standard Model Background ◽  
Beyond The Standard Model ◽  
Gauge Bosons ◽  
Model Background ◽  
The Standard Model

Recent searches for physics beyond the Standard Model at high energy colliders are presented. The main focus is on searches for supersymmetry, extra dimensions and new gauge bosons. In all search analyses the data are found to agree well with the Standard Model background expectation and no evidence for contributions from physics beyond the Standard Model is found. The data are thus used to place limits on new physics scenarios.

scholarly journals Physics Beyond The Standard Model: Experimental

2001 ◽  
Vol 16 (supp01a) ◽  
pp. 92-103 ◽  
Author(s):  
R. L. Culbertson
Keyword(s):  
Standard Model ◽  
Extra Dimensions ◽  
Large Extra Dimensions ◽  
High Energy ◽  
Higgs Bosons ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Model Independent

The search for physics beyond the Standard Model includes Technicolor particles, Higgs Bosons, compositeness, many variations of Supersymmetry, large extra dimensions, model-independent searches for anomalies, and other topics. This article reports a subset of these ongoing searches at the high-energy colliders, Tevatron, HERA and LEP.

scholarly journals Diffuse ultra-high energy neutrino fluxes and physics beyond the Standard Model

2010 ◽  
Vol 690 (1) ◽  
pp. 42-47 ◽  
Author(s):  
Atri Bhattacharya ◽  
Sandhya Choubey ◽  
Raj Gandhi ◽  
Atsushi Watanabe
Keyword(s):  
Standard Model ◽  
High Energy ◽  
Beyond The Standard Model ◽  
Ultra High Energy ◽  
High Energy Neutrino ◽  
Energy Neutrino ◽  
The Standard Model ◽  
Neutrino Fluxes

Probing space–time noncommutativity in the top quark pair production at e+e- collider

2014 ◽  
Vol 29 (27) ◽  
pp. 1450156 ◽  
Author(s):  
Ravi S. Manohar ◽  
J. Selvaganapathy ◽  
Prasanta Kumar Das
Keyword(s):  
Standard Model ◽  
Pair Production ◽  
Top Quark ◽  
Linear Collider ◽  
Standard Model Prediction ◽  
Orientation Angle ◽  
Laboratory Frame ◽  
The Standard Model ◽  
Rapidity Distributions ◽  
Azimuthal Asymmetries

The forward–backward asymmetry observed in the top quark pair production at the Fermilab Tevatron points toward the existence of beyond the standard model physics. We have studied the top quark pair production [Formula: see text] in the TeV energy electron–positron linear collider to the leading order of the noncommutative parameter Θμν in the noncommutative standard model. We have made a detailed laboratory frame analysis of the time-averaged cross-section, polar, azimuthal angular distributions, transverse momentum and rapidity distributions, polar (forward–backward) and azimuthal asymmetries of the top-quark pair production in the presence of earth's rotation. We investigated their dependence on the orientation angle of the noncommutative vector η and the noncommutative scale Λ and found that those deviates from the standard model distributions significantly. The azimuthal distribution which is flat in the standard model deviates largely for η = π/2 and Λ = 700 GeV at the fixed machine energy E com = 1000 GeV . We found that the polar distribution deviates largely from the standard model distribution for η = π/2 and Λ = 500 GeV . The azimuthal asymmetry Aϕ which is zero in the standard model can be as large as 4% for Λ = 500 GeV and η = π/2 at the fixed machine energy E com = 1000 GeV . Assuming that the future TeV linear collider will observe Aϕ = ±0.01 we find Λ≤750(860) GeV corresponding to η = π/2. Similarly, corresponding to polar asymmetry A FBz = 0.5078 (which deviates from the standard model prediction by 1%), we find Λ≤760 GeV at the fixed machine energy E com = 1000 GeV for η = π/2.

scholarly journals Search for single production of vectorlike top partners through th channel at the HE-LHC and FCC-hh

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Xi-Yan Tian ◽  
Liu-Feng Du ◽  
Yao-Bei Liu
Keyword(s):  
Standard Model ◽  
Production Cross ◽  
Branching Fraction ◽  
Hadron Collider ◽  
High Energy ◽  
New Physics ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Single Production ◽  
Integrated Luminosity

AbstractThe vectorlike top partners are potential signature of some new physics beyond the Standard Model at the TeV scale. In this paper, we propose to search for the vectorlike T quark with charge 2/3 in the framework of a simplified model where the top partners only couples with the third generation of Standard Model quarks. We investigate the observability for electroweak production of a vectorlike T quark in association with a standard model bottom quark through the process $$pp \rightarrow T\bar{b}j$$ p p → T b ¯ j with the subsequent decay mode of $$T\rightarrow t(\rightarrow b W^+\rightarrow b \ell ^{+} \nu _{\ell })h( \rightarrow \gamma \gamma )$$ T → t ( → b W + → b ℓ + ν ℓ ) h ( → γ γ ) , at the proposed High Energy Large Hadron Collider (HE-LHC) and Future Circular Collider in hadron-hadron mode (FCC-hh) including the realistic detector effects. The 95% confidence level excluded regions and the $$5\sigma $$ 5 σ discovery reach in the parameter plane of $$\kappa _{T}-m_T$$ κ T - m T , are respectively obtained at the HE-LHC with the integrated luminosity of 15 ab$$^{-1}$$ - 1 and the FCC-hh with the integrated luminosity of 30 ab$$^{-1}$$ - 1 . We also analyze the projected sensitivity in terms of the production cross section times branching fraction at the HE-LHC and FCC-hh.

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