scholarly journals EXPERIMENTAL TESTS ON THE LIFETIME ASYMMETRY

2011 ◽  
Vol 26 (13) ◽  
pp. 987-998 ◽  
Author(s):  
ZHI-QIANG SHI ◽  
GUANG-JIONG NI
Keyword(s):  
Cross Section ◽  
Z Boson ◽  
Particle Physics ◽  
Test Problem ◽  
Precise Measurement ◽  
Experimental Tests ◽  
Moller Scattering ◽  
The Standard Model ◽  
Integrated Cross Section ◽  
Important Significance

The experimental test problem of the left–right polarization-dependent lifetime asymmetry is discussed. It shows that the existing experiments cannot demonstrate the lifetime asymmetry to be right or wrong after analyzing the measurements on the neutron, the muon and the tau lifetime, as well as the g-2 experiment. However, it is pointed out emphatically that the SLD and the E158 experiments, the measurements of the left–right integrated cross section asymmetry in Z boson production by e+e- collisions and by electron–electron Møller scattering, can indirectly demonstrate the lifetime asymmetry. In order to directly demonstrate the lifetime asymmetry, we propose some possible experiments on the decays of polarized muons. The precise measurement of the lifetime asymmetry could have important significance for building a muon collider, also in cosmology and astrophysics. It would provide a sensitive test of the standard model in particle physics and allow for exploration of the possible V+A interactions.

scholarly journals STANDARD MODEL HIGGS COMBINED RESULT FROM CDF

2001 ◽  
Vol 16 (supp01b) ◽  
pp. 825-827
Author(s):  
◽  
JOÃO GUIMARÃES DA COSTA
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Z Boson ◽  
Decay Channel ◽  
Vector Boson ◽  
Associated Production ◽  
The Standard Model ◽  
The Individual ◽  
Cross Section Limit

The Tevatron is expected to be most sensitive to the Standard Model Higgs in its associated production with a W or Z boson. The Collider Detector at Fermilab (CDF) has performed individual searches for such production in each decay channel of the vector boson, assuming that the Higgs decays to [Formula: see text]. These searches use data collected by CDF during the 1992-95 run. The individual results are reviewed, and a combined cross section limit is presented.

scholarly journals Challenging the standard model by high-precision comparisons of the fundamental properties of protons and antiprotons

2018 ◽  
Vol 376 (2116) ◽  
pp. 20170275 ◽  
Author(s):  
S. Ulmer ◽  
A. Mooser ◽  
H. Nagahama ◽  
S. Sellner ◽  
C. Smorra
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
Precise Measurement ◽  
Penning Trap ◽  
Magnetic Moments ◽  
Fundamental Properties ◽  
Stringent Constraint ◽  
The Standard Model ◽  
Charge Parity ◽  
Time Invariance

The BASE collaboration investigates the fundamental properties of protons and antiprotons, such as charge-to-mass ratios and magnetic moments, using advanced cryogenic Penning trap systems. In recent years, we performed the most precise measurement of the magnetic moments of both the proton and the antiproton, and conducted the most precise comparison of the proton-to-antiproton charge-to-mass ratio. In addition, we have set the most stringent constraint on directly measured antiproton lifetime, based on a unique reservoir trap technique. Our matter/antimatter comparison experiments provide stringent tests of the fundamental charge–parity–time invariance, which is one of the fundamental symmetries of the standard model of particle physics. This article reviews the recent achievements of BASE and gives an outlook to our physics programme in the ELENA era. This article is part of the Theo Murphy meeting issue ‘Antiproton physics in the ELENA era’.

scholarly journals Observables for model-independent detections of Z′ boson at the ILC

2015 ◽  
Vol 30 (16) ◽  
pp. 1550087
Author(s):  
V. Skalozub ◽  
I. Kucher
Keyword(s):  
Cross Section ◽  
Z Boson ◽  
Axial Vector ◽  
Effective Lagrangian ◽  
The Standard Model ◽  
Model Predictions ◽  
Model Independent ◽  
Vector Formula ◽  
Two Parameter

The integral observables for model-independent detections of Abelian Z′ gauge boson in e+e- → μ+μ-(τ+τ-) process with unpolarized beams at the ILC energies are proposed. They are based on the differential cross-section of deviations from the standard model predictions calculated with a low energy effective Lagrangian and taking into consideration the relations between the Z′ couplings to the fermions derived already. Due to these relations, the cross-section exhibits angular distribution giving a possibility for introducing one- or two-parameter observables which effectively fit the mass mZ′, the axial-vector [Formula: see text] and the product of vector couplings vevμ(vevτ). A discovery reach for the Z′ is estimated for two of introduced observables. Determination of the basic Z′ model is discussed. Comparison with other results and approaches is given.

scholarly journals Current Issues in the Phenomenology of Particle Physics

1997 ◽  
Vol 12 (31) ◽  
pp. 5531-5554 ◽  
Author(s):  
John Ellis
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Present Status ◽  
Particle Physics ◽  
Neutrino Oscillations ◽  
Experimental Tests ◽  
Grand Unification ◽  
The Standard Model

The present status of the Standard Model and its experimental tests are reviewed, including indications on the likely mass of the Higgs boson. Also discussed are the motivations for supersymmetry and grand unification, searches for sparticles at LEP, neutrino oscillations, and the prospects for physics at the LHC.

scholarly journals The Standard Model

2012 ◽  
Vol 370 (1961) ◽  
pp. 805-817 ◽  
Author(s):  
Tara Shears
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Particle Physics ◽  
Experimental Tests ◽  
Fundamental Particles ◽  
The Standard Model ◽  
Fundamental Forces ◽  
Physics Experiments

The Standard Model is the theory used to describe the interactions between fundamental particles and fundamental forces. It is remarkably successful at predicting the outcome of particle physics experiments. However, the theory has not yet been completely verified. In particular, one of the most vital constituents, the Higgs boson, has not yet been observed. This paper describes the Standard Model, the experimental tests of the theory that have led to its acceptance and its shortcomings.

scholarly journals Toward Three-Loop Feynman Massive Diagram Calculations

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 975
Author(s):  
Ievgen Dubovyk ◽  
Johann Usovitsch ◽  
Krzysztof Grzanka
Keyword(s):  
Differential Equation ◽  
Z Boson ◽  
Particle Physics ◽  
Numerical Solutions ◽  
New Physics ◽  
Weak Mixing ◽  
Feynman Integrals ◽  
Mixing Angles ◽  
The Standard Model ◽  
Decay Widths

There are many methods of searching for traces of the so-called new physics in particle physics. One of them, and the main focus of this paper, is athe study of the Z-boson decay in e+e− collisions. An improvement in the precision of calculations of the Standard Model (SM) electroweak pseudo-observables, such as scattering asymmetries, effective weak mixing angles, and decay widths, related to the Z-boson will meet severe experimental requirements at the planned e+e− colliders and will increase the chance to detect non-standard effects in experimental analysis. To reach this goal, one has to calculate the next order of perturbative SM theory, namely three-loop Feynman integrals. We discuss the complexity of the problem, as well as the methods crucial for completing three-loop calculations. We show several numerical solutions for some three-loop Feynman integrals using sector decomposition, Mellin–Barnes (MB), and differential equation methods.

EXPERIMENTS ON WIMPS, SIMPS, AND HOT DARK MATTER

1994 ◽  
Vol 03 (supp01) ◽  
pp. 43-52
Author(s):  
DAVID O. CALDWELL
Keyword(s):  
Dark Matter ◽  
Cross Section ◽  
Cross Sections ◽  
Particle Physics ◽  
Direct Detection ◽  
Dark Matter Particle ◽  
Dirac Particles ◽  
The Standard Model ◽  
Ionization Detectors ◽  
The Universe

The particle which constitutes more than 90% of the mass of the universe is not one of those in the Standard Model of particle physics. The search for this dark matter particle has now eliminated or severely restricted many candidates. While accelerator-produced results and indirect searches have helped, the most extensive exclusions have come from attempts at direct detection using semiconductor ionization detectors. The region excluded by direct detection extends over 12 orders of magnitude in particle mass and 20 orders of magnitude in cross section for Dirac particles. The need is now to get to cross sections less than one-tenth the weak cross section for Dirac masses >20 GeV and to use detectors having nuclei with spin for Majorana masses ≳10 GeV. Light neutrinos, while not detectable directly, can be eliminated as dominant dark matter if the 17-keV neutrino exists.

scholarly journals Lorentz violation, gravitoelectromagnetic field and Bhabha scattering

2018 ◽  
Vol 33 (02) ◽  
pp. 1850015 ◽  
Author(s):  
A. F. Santos ◽  
Faqir C. Khanna
Keyword(s):  
General Relativity ◽  
Standard Model ◽  
Cross Section ◽  
Particle Physics ◽  
Planck Scale ◽  
Lorentz Violation ◽  
Lorentz Symmetry ◽  
Standard Model Extension ◽  
Bhabha Scattering ◽  
The Standard Model

Lorentz symmetry is a fundamental symmetry in the Standard Model (SM) and in General Relativity (GR). This symmetry holds true for all models at low energies. However, at energies near the Planck scale, it is conjectured that there may be a very small violation of Lorentz symmetry. The Standard Model Extension (SME) is a quantum field theory that includes a systematic description of Lorentz symmetry violations in all sectors of particle physics and gravity. In this paper, SME is considered to study the physical process of Bhabha Scattering in the Gravitoelectromagnetism (GEM) theory. GEM is an important formalism that is valid in a suitable approximation of general relativity. A new nonminimal coupling term that violates Lorentz symmetry is used in this paper. Differential cross-section for gravitational Bhabha scattering is calculated. The Lorentz violation contributions to this GEM scattering cross-section are small and are similar in magnitude to the case of the electromagnetic field.

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