scholarly journals Possible bilepton resonances in like-sign pairs

2019 ◽  
Vol 34 (10) ◽  
pp. 1950076 ◽  
Author(s):  
Claudio Corianò ◽  
Paul H. Frampton
Keyword(s):  
Standard Model ◽  
Pair Production ◽  
Model Prediction ◽  
Standard Model Prediction ◽  
Mass Range ◽  
Entire Mass Range ◽  
Large Ratio ◽  
The Standard Model ◽  
Integrated Luminosity

We consider pair production of bileptons Y[Formula: see text]Y[Formula: see text] at the LHC for the presently accumulated integrated luminosity of 150/fb. It is shown that the entire mass range 800 GeV [Formula: see text]M(Y) [Formula: see text] 2000 GeV can be successfully searched. A bilepton resonance will have an exceptionally large ratio of signal to background because the Standard Model prediction is so infinitesimal. A 5[Formula: see text] discovery is quite feasible.

scholarly journals Standard Model prediction of the Bc lifetime

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Jason Aebischer ◽  
Benjamín Grinstein
Keyword(s):  
Standard Model ◽  
Model Prediction ◽  
Strange Quark ◽  
Standard Model Prediction ◽  
New Physics ◽  
Operator Product ◽  
Special Focus ◽  
Third Order ◽  
Clear Cut ◽  
The Standard Model

Abstract Applying an operator product expansion approach we update the Standard Model prediction of the Bc lifetime from over 20 years ago. The non-perturbative velocity expansion is carried out up to third order in the relative velocity of the heavy quarks. The scheme dependence is studied using three different mass schemes for the $$ \overline{b} $$ b ¯ and c quarks, resulting in three different values consistent with each other and with experiment. Special focus has been laid on renormalon cancellation in the computation. Uncertainties resulting from scale dependence, neglecting the strange quark mass, non-perturbative matrix elements and parametric uncertainties are discussed in detail. The resulting uncertainties are still rather large compared to the experimental ones, and therefore do not allow for clear-cut conclusions concerning New Physics effects in the Bc decay.

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 Form Factor Measurements at BESIII for an Improved Standard Model Prediction of the Muon g-2

2018 ◽  
Vol 46 ◽  
pp. 1860026
Author(s):  
Marco Destefanis
Keyword(s):  
Form Factor ◽  
Standard Model ◽  
Model Prediction ◽  
Particle Physics ◽  
Standard Model Prediction ◽  
Final States ◽  
Direct Measurements ◽  
The Standard Model ◽  
Data Driven Approach

The anomalous part of the magnetic moment of the muon, (g-2)[Formula: see text], allows for one of the most precise tests of the Standard Model of particle physics. We report on recent results by the BESIII Collaboration of exclusive hadronic cross section channels, such as the 2[Formula: see text], 3[Formula: see text], and 4[Formula: see text] final states. These measurements are of utmost importance for an improved calculation of the hadronic vacuum polarization contribution of (g-2)[Formula: see text], which currenty is limiting the overall Standard Model prediction of this quantity. BESIII has furthermore also intiatated a programme of spacelike transition form factor measurements, which can be used for a determination of the hadronic light-by-light contribution of (g-2)[Formula: see text] in a data-driven approach. These results are of relevance in view of the new and direct measurements of (g-2)[Formula: see text] as foreseen at Fermilab/USA and J-PARC/Japan.

scholarly journals A Heavy Scalar at the LHC from Vector-Boson Fusion

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Qiurong Mou ◽  
Sibo Zheng
Keyword(s):  
Standard Model ◽  
Vector Boson ◽  
Mass Range ◽  
New Physics ◽  
Vector Boson Fusion ◽  
Mixing Angle ◽  
The Standard Model ◽  
Scalar Mass ◽  
Event Simulations ◽  
Integrated Luminosity

A hypothetical scalar mixed with the standard model Higgs appears in few contexts of new physics. This study addresses the question what mass range is in the reach of 14 TeV LHC given different magnitudes of mixing angle α, where event simulations are based on production from vector-boson fusion channel and decays into SM leptons through WW or ZZ. It indicates that heavy scalar mass up to 539 GeV and 937 GeV can be excluded by integrated luminosity of 300 fb-1 and 3000 fb-1, respectively, for sin2α larger than 0.04.

scholarly journals THEORY OF THE τ LEPTON ANOMALOUS MAGNETIC MOMENT

2007 ◽  
Vol 22 (03) ◽  
pp. 159-179 ◽  
Author(s):  
S. EIDELMAN ◽  
M. PASSERA
Keyword(s):  
Standard Model ◽  
Model Prediction ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Standard Model Prediction ◽  
Low Energy ◽  
Leading Order ◽  
The Standard Model

This paper reviews and updates the Standard Model prediction of the τ lepton g-2. Updated QED and electroweak contributions are presented, together with new values of the leading-order hadronic term, based on the recent low energy e+ e- data from BaBar, CMD-2, KLOE and SND, and hadronic light-by-light contribution. The total prediction is confronted to the available experimental bounds on the τ lepton anomaly, and prospects for its future measurements are briefly discussed.

scholarly journals Pair production of new heavy leptons with U(1)′ charge at linear colliders

2014 ◽  
Vol 29 (11n12) ◽  
pp. 1450055 ◽  
Author(s):  
V. Arı ◽  
O. Çakır ◽  
S. Kuday
Keyword(s):  
Standard Model ◽  
Pair Production ◽  
Cross Sections ◽  
Production Cross ◽  
Center Of Mass ◽  
Mass Range ◽  
Mixing Parameter ◽  
The Standard Model ◽  
Linear Colliders ◽  
Heavy Leptons

We study the pair production of new heavy leptons within a new U(1)′ symmetry extension of the Standard Model. Because of the new symmetry, the production and decay modes of the new heavy leptons would be different from those of three families of the standard model. The pair production cross-sections depending on the mixing parameter and the mass of heavy leptons have been calculated for the center-of-mass energies of 0.5 TeV, 1 TeV and 3 TeV. The accessible ranges of the parameters have been obtained for different luminosity projections at linear colliders. The search can be performed within the range of mixing parameter -1<x<-0.35 and 0.05<x<1, given that the heavy lepton mass Ml′ = 400 GeV at [Formula: see text] and L int = 100 fb -1. We find the sensitivity to the range of mixing parameter -1<x<1 for the mass range Ml′<800 GeV at [Formula: see text] and L int = 100 fb -1.

scholarly journals Effect of Systematic Uncertainty Estimation on the Muon g - 2 Anomaly

2022 ◽  
Vol 258 ◽  
pp. 09002
Author(s):  
Glen Cowan
Keyword(s):  
Standard Deviation ◽  
Standard Model ◽  
Model Prediction ◽  
Standard Model Prediction ◽  
Statistical Significance ◽  
Uncertainty Estimation ◽  
Relative Uncertainty ◽  
Systematic Uncertainties ◽  
The Standard Model ◽  
The Impact

The statistical significance that characterizes a discrepancy between a measurement and theoretical prediction is usually calculated assuming that the statistical and systematic uncertainties are known. Many types of systematic uncertainties are, however, estimated on the basis of approximate procedures and thus the values of the assigned errors are themselves uncertain. Here the impact of the uncertainty on the assigned uncertainty is investigated in the context of the muon g - 2 anomaly. The significance of the observed discrepancy between the Standard Model prediction of the muon’s anomalous magnetic moment and measured values are shown to decrease substantially if the relative uncertainty in the uncertainty assigned to the Standard Model prediction exceeds around 30%. The reduction in sensitivity increases for higher significance, so that establishing a 5σ effect will require not only small uncertainties but the uncertainties themselves must be estimated accurately to correspond to one standard deviation.

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