THE GAMMA–GAMMA INTERACTION: A CRITICAL TEST OF THE STANDARD MODEL

2009 ◽  
Vol 24 (18n19) ◽  
pp. 3276-3285
Author(s):  
PHILIP YOCK
Keyword(s):  
Standard Model ◽  
Linear Collider ◽  
International Linear Collider ◽  
Strong Interactions ◽  
Acceleration Technique ◽  
Wakefield Acceleration ◽  
Electron Positron ◽  
Proposed Model ◽  
The Standard Model ◽  
Order Of Magnitude

Data from the Large Electron Positron collider (LEP) at CERN on hadron production in gamma-gamma interactions exceed the predictions of the standard model by an order of magnitude at the highest observed transverse momenta in three channels. The amplitude for the process is asymptotically proportional to the sum of the squares of the charges of quarks. The data are suggestive of models where quarks have unit charges, or larger, and where partons have substructure. A previously proposed model of electro-strong interactions includes both these features. Definitive measurements could be made with either of the linear electron-positron colliders that have been proposed, viz. the International Linear Collider (ILC) or the Compact Linear Collider (CLIC). However, an electron-electron collider employing the recently developed "plasma wakefield" acceleration technique could provide the most affordable option. An independent check of the multi-muon events that were recently reported at Fermilab could also be made with this type of collider.

scholarly journals Indirect reach of heavy MSSM Higgs bosons by precision measurements at future lepton colliders

2015 ◽  
Vol 30 (33) ◽  
pp. 1550192 ◽  
Author(s):  
Mitsuru Kakizaki ◽  
Shinya Kanemura ◽  
Mariko Kikuchi ◽  
Toshinori Matsui ◽  
Hiroshi Yokoya
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
W Boson ◽  
Linear Collider ◽  
Standard Model Prediction ◽  
Branching Fraction ◽  
International Linear Collider ◽  
Higgs Bosons ◽  
Boson Mass ◽  
Electron Positron

In the Minimal Supersymmetric Standard Model (MSSM), the bottom Yukawa coupling of the Higgs boson can considerably deviate from its Standard Model prediction due to nondecoupling effects. We point out that the ratio of the Higgs boson decay branching fraction to a bottom quark pair and that to a W-boson pair from the same production channel is particularly sensitive to large additional MSSM Higgs boson mass regions at future electron–positron colliders. Based on this precision measurement, we explicitly show the indirect discovery reach of the additional Higgs bosons according to planned programs of the International Linear Collider.

scholarly journals Forward–backward asymmetry in the gauge-Higgs unification at the International Linear Collider

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Shuichiro Funatsu
Keyword(s):  
Standard Model ◽  
Linear Collider ◽  
International Linear Collider ◽  
Gauge Bosons ◽  
Fermion Pair ◽  
Negative Case ◽  
The Standard Model ◽  
Model Predictions ◽  
Kaluza Klein ◽  
Polarised Beams

Abstract The signals of the $$SO(5)\times U(1)$$SO(5)×U(1) gauge-Higgs unification model at the International Linear Collider are studied. In this model, Kaluza–Klein modes of the neutral gauge bosons affect fermion pair productions. The deviations of the forward–backward asymmetries of the $$e^+e^-\rightarrow \bar{b}b$$e+e-→b¯b, $$\bar{t}t$$t¯t processes from the standard model predictions are clearly seen by using polarised beams. The deviations of these values are predicted for two cases, the bulk mass parameters of quarks are positive and negative case.

ASSOCIATED PRODUCTION OF LIGHT PSEUDOSCALAR BOSON η WITH TOP QUARK PAIRS IN THE SLH MODEL AT THE ILC

2011 ◽  
Vol 26 (21) ◽  
pp. 1577-1586 ◽  
Author(s):  
JINZHONG HAN ◽  
DAPENG YANG ◽  
XUELEI WANG
Keyword(s):  
Standard Model ◽  
Cross Section ◽  
Cross Sections ◽  
Top Quark ◽  
Linear Collider ◽  
International Linear Collider ◽  
Quark Pairs ◽  
Associated Production ◽  
The Standard Model ◽  
The Cross

The light pseudoscalar boson η is the typical particle predicted by the Simplest Little Higgs (SLH) model. In this paper, we investigate some processes of the associated production of a light pseudoscalar boson η with a pair of top quarks in the SLH model at the International Linear Collider (ILC), i.e. [Formula: see text] and [Formula: see text]. We find that the cross-sections of these two processes could reach [Formula: see text] fb in the favorite parameter space in the SLH model, which is consistent with the results of the cross-section of [Formula: see text] in the standard model and the cross-section of [Formula: see text] in the minimal supersymmetric standard model. It should be clear that hundreds to thousands of η can be produced at the ILC per year, these processes of [Formula: see text] are really interesting in testing the standard model and searching the signs of the SLH model.

scholarly journals Searching for charged lepton flavor violation at ep colliders

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Stefan Antusch ◽  
A. Hammad ◽  
Ahmed Rashed
Keyword(s):  
Standard Model ◽  
Charged Lepton ◽  
Neutral Current ◽  
Effective Theory ◽  
Theory Approach ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model ◽  
Order Of Magnitude

Abstract We investigate the sensitivity of electron-proton (ep) colliders for charged lepton flavor violation (cLFV) in an effective theory approach, considering a general effective Lagrangian for the conversion of an electron into a muon or a tau via the effective coupling to a neutral gauge boson or a neutral scalar field. For the photon, the Z boson and the Higgs particle of the Standard Model, we present the sensitivities of the LHeC for the coefficients of the effective operators, calculated from an analysis at the reconstructed level. As an example model where such flavor changing neutral current (FCNC) operators are generated at loop level, we consider the extension of the Standard Model by sterile neutrinos. We show that the LHeC could already probe the LFV conversion of an electron into a muon beyond the current experimental bounds, and could reach more than an order of magnitude higher sensitivity than the present limits for LFV conversion of an electron into a tau. We discuss that the high sensitivities are possible because the converted charged lepton is dominantly emitted in the backward direction, enabling an efficient separation of the signal from the background.

scholarly journals RECENT τ LEPTON RESULTS FROM BABAR

2014 ◽  
Vol 35 ◽  
pp. 1460440
Author(s):  
ALBERTO LUSIANI
Keyword(s):  
Standard Model ◽  
Branching Fractions ◽  
Charged Particles ◽  
Babar Collaboration ◽  
Final States ◽  
Final State ◽  
Experimental Knowledge ◽  
Electron Positron ◽  
The Standard Model ◽  
Positron Collisions

We report recent measurements on τ leptons obtained by the BABAR collaboration using the entire recorded sample of electron-positron collisions at and around the Υ(4S) (about 470fb-1). The events were recorded at the PEP-II asymmetric collider at the SLAC National Accelerator Laboratory. The measurements include high multiplicity τ decay branching fractions with 3 or 5 charged particles in the final state, a search for the second class current the τ decay τ → πη′ν, τ branching fractions into final states containing two KS mesons, [Formula: see text], with h = π, K, and preliminary measurements of hadronic spectra of τ decays with three hadrons (τ- → h-h+h-ντ decays, where h = π, K). The results improve the experimental knowledge of the τ lepton properties and can be used to improve the precision tests of the Standard Model.

scholarly journals Effective field theory, past and future

2016 ◽  
Vol 31 (06) ◽  
pp. 1630007 ◽  
Author(s):  
Steven Weinberg
Keyword(s):  
Field Theory ◽  
General Relativity ◽  
Effective Field Theories ◽  
Standard Model ◽  
Effective Field Theory ◽  
Effective Field ◽  
Field Theories ◽  
Strong Interactions ◽  
The Standard Model ◽  
Theory Of Gravitation

I reminisce about the early development of effective field theories of the strong interactions, comment briefly on some other applications of effective field theories, and then take up the idea that the Standard Model and General Relativity are the leading terms in an effective field theory. Finally, I cite recent calculations that suggest that the effective field theory of gravitation and matter is asymptotically safe.

SCALE GAUGE SYMMETRY AND THE STANDARD MODEL

1990 ◽  
Vol 05 (22) ◽  
pp. 4225-4240 ◽  
Author(s):  
J. SOLÀ
Keyword(s):  
Gauge Symmetry ◽  
Standard Model ◽  
Cosmological Constant ◽  
Minimal Model ◽  
Harmonic Map ◽  
Strong Interactions ◽  
Cosmological Constant Problem ◽  
The Standard Model ◽  
Conformal Gauge ◽  
Scalar Sector

We speculate on a version of the "standard" model of the electroweak and strong interactions coupled to gravity and equipped with a spontaneously broken, anomalous, conformal gauge symmetry. The scalar sector is virtually absent in the minimal model but in the general case it shows up in the form of a nonlinear harmonic map Lagrangian. A Euclidean approach to the cosmological constant problem is also addressed in this framework.

Preliminary conceptual design about the CEPC calorimeters

2016 ◽  
Vol 31 (33) ◽  
pp. 1644026 ◽  
Author(s):  
Haijun Yang
Keyword(s):  
Conceptual Design ◽  
Linear Collider ◽  
International Linear Collider ◽  
Electromagnetic Calorimeter ◽  
Hadronic Jets ◽  
Baseline Design ◽  
Active Sensor ◽  
Electron Positron ◽  
Physics Potential ◽  
Conceptual Design Report

The Circular Electron Positron Collider (CEPC) as a Higgs factory was proposed in September 2013. The preliminary conceptual design report was completed in 2015.1 The CEPC detector design was using International Linear Collider Detector — ILD2 as an initial baseline. The CEPC calorimeters, including the high granularity electromagnetic calorimeter (ECAL) and the hadron calorimeter (HCAL), are designed for precise energy measurements of electrons, photons, taus and hadronic jets. The basic resolution requirements for the ECAL and HCAL are about 16%[Formula: see text][Formula: see text] (GeV) and 50%[Formula: see text][Formula: see text] (GeV), respectively. To fully exploit the physics potential of the Higgs, [Formula: see text], [Formula: see text] and related Standard Model processes, the jet energy resolution is required to reach 3%–4%, or 30%/[Formula: see text] (GeV) at energies below about 100 GeV. To achieve the required performance, a Particle Flow Algorithm (PFA) — oriented calorimetry system is being considered as the baseline design. The CEPC ECAL detector options include silicon–tungsten or scintillator–tungsten structures with analog readout, while the HCAL detector options have scintillator or gaseous detector as the active sensor and iron as the absorber. Some latest R&D studies about ECAL and HCAL within the CEPC working group is also presented.

Electroweak Interactions and W, Z Boson Properties

2020 ◽  
Author(s):  
Maarten Boonekamp ◽  
Matthias Schott
Keyword(s):  
Standard Model ◽  
Weak Interaction ◽  
Top Quark ◽  
Quantum Electrodynamics ◽  
Weak Interactions ◽  
Higgs Field ◽  
Nuclear Research ◽  
Strong Interactions ◽  
Weak Boson ◽  
The Standard Model

With the huge success of quantum electrodynamics (QED) to describe electromagnetic interactions in nature, several attempts have been made to extend the concept of gauge theories to the other known fundamental interactions. It was realized in the late 1960s that electromagnetic and weak interactions can be described by a single unified gauge theory. In addition to the photon, the single mediator of the electromagnetic interaction, this theory predicted new, heavy particles responsible for the weak interaction, namely the W and the Z bosons. A scalar field, the Higgs field, was introduced to generate their mass. The discovery of the mediators of the weak interaction in 1983, at the European Center for Nuclear Research (CERN), marked a breakthrough in fundamental physics and opened the door to more precise tests of the Standard Model. Subsequent measurements of the weak boson properties allowed the mass of the top quark and of the Higgs Boson to be predicted before their discovery. Nowadays, these measurements are used to further probe the consistency of the Standard Model, and to place constrains on theories attempting to answer still open questions in physics, such as the presence of dark matter in the universe or unification of the electroweak and strong interactions with gravity.

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