PRECISION LOW ENERGY WEAK NEUTRAL CURRENT EXPERIMENTS

1995 ◽  
Vol 10 (39) ◽  
pp. 2979-2992 ◽  
Author(s):  
K.S. KUMAR ◽  
E.W. HUGHES ◽  
R. HOLMES ◽  
P.A. SOUDER
Keyword(s):  
High Energy Physics ◽  
Neutral Current ◽  
High Energy ◽  
New Physics ◽  
Coupling Constants ◽  
Current Status ◽  
Weak Neutral Current ◽  
Weak Mixing Angle ◽  
Precision Data ◽  
Moller Scattering

Precision measurements of weak neutral current amplitudes at [Formula: see text] are a sensitive probe of contact interactions arising from new high energy physics. Such measurements significantly enhance the analysis of precision data on the Z0 resonance, permitting tests of the running of the electroweak coupling constants. The behavior of the coupling constants as a function of Q2 can reveal the presence of many possible new physics scenarios, such as new gauge bosons, superparticles and substructure; some of these effects are difficult to observe on the Z0 pole. In order to probe energy scales up to 1 TeV, future low Q2 measurements must be precise enough to measure electroweak radiative corrections. Two experimental programs which aim to reach this sensitivity are deep inelastic neutrino nucleon scattering and atomic parity violation experiments. Another important technique is polarized electron scattering off unpolarized targets. We review the current status and future prospects of such measurements. We present an experimental design to measure the left-right parity violating asymmetry in polarized Møller scattering (e−e−→e−e−), which could constitute the most precise measurement of the weak mixing angle [Formula: see text] at [Formula: see text].

scholarly journals W-boson production in the high energy electron-photon collisions

2019 ◽  
pp. 41-50
Author(s):  
Ivan A. Shershan ◽  
Tatiana V. Shishkina
Keyword(s):  
Standard Model ◽  
Cross Sections ◽  
W Boson ◽  
High Energy ◽  
New Physics ◽  
Coupling Constants ◽  
Boson Production ◽  
The Standard Model ◽  
Electron Photon ◽  
W Boson Production

In this paper the analysis of W-boson production process in high-energy electron-photon collisions as a tool to search for deviations from the Standard Model is considered. In particular, a set of extended gauge models, including anomalous multi-boson interactions, are discussed as a promising way for «new physics» study. A numerical analysis of the total cross sections of the processes was carried out. The lowest order radiative corrections in the soft-photon approximation within the Standard Model are taken into account. Calculations beyond the Standard Model was performed, the kinematic features of the cross sections were identified. The restrictions on the anomalous triple gauge boson coupling constants were analyzed and the kinematic areas to the search for their manifestations were obtained during the experiments at the International Linear Collider. The paper shows that the search for «new physics» effects based on electron-photon collisions around the W-boson production peak is the maximal promising. It was also shown that future experiments at high luminosity linear colliders will significantly clarify the constraints on anomalous gauge coupling constants.

scholarly journals tt̄H Coupling Measurement with the ATLAS Detector at the LHC

2018 ◽  
Vol 182 ◽  
pp. 02052
Author(s):  
Asma Hadef
Keyword(s):  
Higgs Boson ◽  
Cross Sections ◽  
Top Quark ◽  
High Energy Physics ◽  
Center Of Mass ◽  
High Energy ◽  
New Physics ◽  
Decay Modes ◽  
Center Of Mass Energy ◽  
Higgs Decay

The Higgs boson was discovered on the 4th of July 2012 with a mass around 125 GeV by ATLAS and CMS experiments at LHC. Determining the Higgs properties (production and decay modes, couplings,...) is an important part of the high-energy physics programme in this decade. A search for the Higgs boson production in association with a top quark pair (tt̄H) at ATLAS [1] is summarized in this paper at an unexplored center-of-mass energy of 13 TeV, which could allow a first direct measurement of the top quark Yukawa coupling and could reveal new physics. The tt̄H analysis in ATLAS is divided into 3 channels according to the Higgs decay modes: H → Hadrons, H → Leptons and H → Photons. The best-fit value of the ratio of observed and Standard Model cross sections of tt̄H production process, using 2015-2016 data and combining all tt̄H final states, is 1:8±0:7, corresponds to 2:8σ (1:8σ) observed (expected) significance.

scholarly journals CP VIOLATION AND BEAUTY DECAYS — A CASE STUDY OF HIGH IMPACT, HIGH SENSITIVITY AND EVEN HIGH PRECISION PHYSICS

2000 ◽  
Vol 15 (08) ◽  
pp. 1079-1156
Author(s):  
I. I. BIGI
Keyword(s):  
Cp Violation ◽  
Degrees Of Freedom ◽  
High Energy Physics ◽  
Dipole Moments ◽  
High Sensitivity ◽  
High Energy ◽  
New Physics ◽  
B Decays ◽  
New Paradigm ◽  
Parametric Reliability

The narrative of these lectures contains three main threads: (i) CP violation despite having so far been observed only in the decays of neutral kaons has been recognized as a phenomenon of truly fundamental importance. The KM ansatz constitutes the minimal implementation of CP violation: without requiring unknown degrees of freedom it can reproduce the known CP phenomenology in a nontrivial way. (ii) The physics of beauty hadrons — in particular their weak decays — opens a novel window onto fundamental dynamics: they usher in a new quark family (presumably the last one); they allow us to determine fundamental quantities of the Standard Model like the b quark mass and the CKM parameters V(cb), V(ub), V(ts) and V(td); they exhibit speedy or even rapid [Formula: see text] oscillations. (iii) Heavy Quark Expansions allow us to treat B decays with an accuracy that would not have been thought possible a mere decade ago. These three threads are joined together in the following manner: (a) Huge CP asymmetries are predicted in B decays, which represents a decisive test of the KM paradigm for CP violation. (b) Some of these predictions are made with high parametric reliability, which (c) can be translated into numerical precision through the judicious employment of novel theoretical technologies. (d) Beauty decays thus provide us with a rich and promising field to search for New Physics and even study some of its salient features. At the end of it there might quite possibly be a New Paradigm for High Energy Physics. There will be some other threads woven into this tapestry: electric dipole moments, and CP violation in other strange and in charm decays.

scholarly journals THE CASE OF αs: Z VERSUS LOW ENERGIES OR, HOW NATURE SHOWS US NEW PHYSICS

1996 ◽  
Vol 11 (18) ◽  
pp. 3195-3225 ◽  
Author(s):  
M. SHIFMAN
Keyword(s):  
High Energy ◽  
New Physics ◽  
Current Status ◽  
Low Energies

The values of αs determined from low and high energy measurements are in irreconcilable contradiction with each other. The current status of the problem is critically reviewed. Consequences of the αs contradiction, in conjunction with other anomalies detected at the Z peak, are discussed. This article has been updated in accordance with experimental numbers reported at summer conferences.

scholarly journals NEW PHYSICS DISCOVERY POTENTIAL IN FUTURE EXPERIMENTS

1998 ◽  
Vol 13 (40) ◽  
pp. 3235-3249 ◽  
Author(s):  
S. I. BITYUKOV ◽  
N. V. KRASNIKOV
Keyword(s):  
Cross Sections ◽  
High Energy Physics ◽  
High Energy ◽  
New Physics ◽  
Physics Simulation ◽  
Discovery Potential ◽  
Proper Definition ◽  
Definition Of ◽  
Physics Experiments ◽  
Energy Physics

We propose a method to estimate the probability of new physics discovery in future high energy physics experiments. Physics simulation gives both the average numbers <Nb> of background and <Ns> of signal events. We find that the proper definition of the significance for <Nb>, <Ns> ≫ 1 is [Formula: see text] in comparison with often used significances: [Formula: see text] and [Formula: see text]. We propose a method of taking into account the systematical errors related to nonexact knowledge of background and signal cross-sections. An account of such systematics is essential in the search for supersymmetry at LHC. We also propose a method for estimating exclusion limits on new physics in future experiments.

scholarly journals Physics at a Higgs factory

2016 ◽  
Vol 31 (33) ◽  
pp. 1644003 ◽  
Author(s):  
Matthew Reece
Keyword(s):  
Hong Kong ◽  
High Energy Physics ◽  
Science And Technology ◽  
High Energy ◽  
New Physics ◽  
Plenary Talk ◽  
Study Program ◽  
Physics Potential ◽  
Electroweak Precision ◽  
Energy Physics

I give an overview of the physics potential at possible future [Formula: see text] colliders, including the ILC, FCC-ee, and CEPC. The goal is to explain some of the measurements that can be done in the context of electroweak precision tests and Higgs couplings, to compare some of the options under consideration, and to put the measurements in context by summarizing their implications for some new physics scenarios. This is a writeup of a plenary talk at the Hong Kong University of Science and Technology Jockey Club Institute for Advanced Study Program on High Energy Physics Conference, 18–21 January 2016. Some previously unpublished electroweak precision results for FCC-ee and CEPC are included.

scholarly journals Testing new physics models with global comparisons to collider measurements: the Contur toolkit

2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Andy Buckley ◽  
Jonathan Butterworth ◽  
Louie Corpe ◽  
Martin Habedank ◽  
Danping Huang ◽  
...  
Keyword(s):  
Standard Model ◽  
High Energy Physics ◽  
High Energy ◽  
New Physics ◽  
Beyond The Standard Model ◽  
Physics Community ◽  
The Standard Model ◽  
Model Independence ◽  
High Degree ◽  
Energy Physics

Measurements at particle collider experiments, even if primarily aimed at understanding Standard Model processes, can have a high degree of model independence, and implicitly contain information about potential contributions from physics beyond the Standard Model. The CONTUR package allows users to benefit from the hundreds of measurements preserved in the RIVET library to test new models against the bank of LHC measurements to date. This method has proven to be very effective in several recent publications from the CONTUR team, but ultimately, for this approach to be successful, the authors believe that the CONTUR tool needs to be accessible to the wider high energy physics community. As such, this manual accompanies the first user-facing version: CONTUR v2. It describes the design choices that have been made, as well as detailing pitfalls and common issues to avoid. The authors hope that with the help of this documentation, external groups will be able to run their own CONTUR studies, for example when proposing a new model, or pitching a new search.

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