scholarly journals Determination of e+e- beam polarization for optimal gauge boson discovery limits

2015 ◽  
Vol 30 (14) ◽  
pp. 1550075
Author(s):  
Ali A. Bagneid

Extra neutral gauge bosons suggested by models beyond the standard model can indirectly show up in e+e- collisions through off-resonance deviations of various physical observables from the corresponding standard model values. We considered leptonic observables and studied the dependence of the deviations on the polarizations of the positron and electron beams. We showed that, for a given model, the magnitude of the deviation of a given observable can attain its maximum value if the polarizations of the positron and electron beams are properly chosen. We determined, for a given model, a single set of beam polarization so that if this set is employed in measuring all considered observables, it produces the highest extra gauge boson discovery limits.

2018 ◽  
Vol 46 ◽  
pp. 1860070
Author(s):  
Anna Lupato

In the Standard Model the electroweak coupling of the gauge bosons to leptons is independent of the lepton flavour. Semileptonic and rare decays of b quarks provide an ideal laboratory to test this property. Any violation of Lepton Flavour Universality would be a clear sign of physics beyond the Standard Model. In this work a review of the Lepton Flavour Universality tests performed using data collected by the LHCb experiment in 2011 and 2012 at a centre of mass energy of 7 and 8 TeV is presented.


2005 ◽  
Vol 20 (22) ◽  
pp. 5164-5173 ◽  
Author(s):  
BEATE HEINEMANN

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.


2019 ◽  
Vol 79 (9) ◽  
Author(s):  
Joachim Herrmann

Abstract A generalized theory of electroweak interaction is developed based on the underlying geometrical structure of the tangent bundle with symmetries arising from transformations of tangent vectors along the fiber axis at a fixed spacetime point given by the SO(3,1) group. Electroweak interaction beyond the standard model (SM) is described by the little groups $$ SU(2)\otimes E^{c}(2)$$SU(2)⊗Ec(2) ($$E^{c}(2)$$Ec(2) is the central extended Euclidian group) which includes the group $$SU(2)\otimes U(1)$$SU(2)⊗U(1) as a limit case. In addition to isospin and hypercharge, two additional quantum numbers arise which explain the existence of families in the SM. The connection coefficients yield the SM gauge potentials but also hypothetical gauge bosons and other hypothetical particles as a Higgs family as well as candidate Dark Matter particles are predicted. Several important consequences for the interaction between dark fermions, dark scalars or dark vector gauge bosons with each other and with SM Higgs and Z-bosons are described.


2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
P. V. Dong ◽  
V. T. N. Huyen ◽  
H. N. Long ◽  
H. V. Thuy

The mixing among gauge bosons in the 3-3-1 models with the discrete symmetries is investigated. To get tribimaximal neutrino mixing, we have to introduce sextets containing neutral scalar components with lepton numberL=1,2. Assignation of VEVs to these fields leads to the mixing of the new gauge bosons and those in the standard model. The mixing in the charged gauge bosons leads to the lepton number violating interactions of theWboson. The same situation happens in the neutral gauge boson sector.


1996 ◽  
Vol 11 (03) ◽  
pp. 409-428 ◽  
Author(s):  
KEITH A. OLIVE ◽  
SEAN T. SCULLY

The current status of big bang nucleosynthesis is reviewed with an emphasis on the comparison between the observational determination of the light element abundances of D , 3 He , 4 He and 7 Li and the predictions from theory. In particular, we present new analyses for 4 He and 7 Li . Implications for physics beyond the standard model are also discussed. In addition, limits on the effective number of neutrino flavors are updated.


2008 ◽  
Vol 23 (24) ◽  
pp. 3849-3861 ◽  
Author(s):  
J.-F. GRIVAZ

Recent searches for physics beyond the Standard Model at high-energy colliders are reviewed, with emphasis on supersymmetry, additional space dimensions, extra gauge bosons, leptoquarks and model-independent searches. The results reported are based on data samples of up to 0.5 and 2.5 fb -1 collected at HERA and at the Tevatron, respectively.


2019 ◽  
Vol 22 (4) ◽  
pp. 318-329 ◽  
Author(s):  
I. A. Shershan Shershan ◽  
T. V. Shishkina Shishkina

The differential and total cross sections of the single gauge boson production in quasielastic high energy electron-photon scattering are obtained within the Standard Model in leading order and next-to-leading order of the perturbative theory. The contribution of divergent part of hard photon bremsstrahlung was included. The anomalous gauge boson coupling in the effective Lagrangian approach were studied. It is shown the analysis of neutral gauge couplings can be fully performed for two constants with different types of symmetries. Numerical analysis has been done. The best conditions were determined for registration of generated effects beyond the Standard Model.


1998 ◽  
Vol 13 (14) ◽  
pp. 2217-2225 ◽  
Author(s):  
CLEMENS A. HEUSCH

Based on the easy availability of highly polarized electron beams, we revisit the need for an early realization of a TeV electron-electron collider. Most EWSB searches can be performed in unique ways at this facility, and the tunable "exotic" quantum numbers of the e-e- initial states can be used as powerful probes for a vairety of forays beyond the Standard Model. There are no accelerator. interaction region, or detector issues that would not compatibly function in the e+e- and e-e- configurations.


2011 ◽  
Vol 26 (18) ◽  
pp. 3051-3063 ◽  
Author(s):  
ERNESTO A. MATUTE

We argue that presymmetry, a hidden predynamical electroweak quark–lepton symmetry that explains the fractional charges and triplication of families, must be extended beyond the Standard Model as to have a residual presymmetry that embraces partner particles and includes the strong sector, so accounting for the twin or mirror partners proposed to alleviate the naturalness problem of the weak scale. It leads to the full duplication of fermions and gauge bosons of the Standard Model independently of the ultraviolet completion of the theory, even if the Higgs particle is discarded by experiment, which adds robustness to twin and mirror symmetries. The established connection is so strongly motivated that the search for twin or mirror matter becomes the possible test of presymmetry. If the physics beyond the Standard Model repairs its left–right asymmetry, mirror symmetry should be the one realized in nature.


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