POSSIBLE CONSEQUENCES OF PARITY CONSERVATION

1992 ◽  
Vol 07 (28) ◽  
pp. 2567-2574 ◽  
Author(s):  
R. FOOT ◽  
H. LEW ◽  
R. R. VOLKAS

It has been shown that parity may be an exact unbroken symmetry of nature. This requires a doubling of the number of physical particles, although only two parameters beyond those in the Standard Model are introduced. We show that the Lagrangian describing parity conserving models can be reformulated in terms of a basis in which each term of the Lagrangian is parity invariant, although gauge invariance is not manifest. We then examine some further experimental signatures of parity conservation. We point out that, in the simplest case, there is one parity-even and one parity-odd physical neutral Higgs mass eigenstate, whose Yukawa coupling constants are [Formula: see text]-that of the Standard Model Higgs boson. Furthermore, half of their widths are generated by almost invisible decay modes. Also, if neutrinos are massive then the ordinary and mirror neutrinos will, in the minimal case, be maximally mixed due to parity conservation. This means that vacuum oscillations can be large, thus providing a possible solution to the solar neutrino problem.

2015 ◽  
Vol 30 (07) ◽  
pp. 1550033 ◽  
Author(s):  
Agostino Devastato ◽  
Fedele Lizzi ◽  
Carlos Valcárcel Flores ◽  
Dmitri Vassilevich

We investigate whether inclusion of dimension 6 terms in the Standard Model Lagrangian may cause the unification of the coupling constants at a scale comprised between 1014and 1017GeV. Particular choice of the dimension 6 couplings is motivated by the spectral action. Given the theoretical and phenomenological constraints, as well as recent data on the Higgs mass, we find that the unification is indeed possible, with a lower unification scale slightly favored.


2014 ◽  
Vol 29 (26) ◽  
pp. 1430055
Author(s):  
Romain Madar ◽  

The newly discovered boson was only observed in diboson final states. The measurement of the fermionic decay modes of this new particle is essential to establish its compatibility with the Standard Model Higgs boson. The two main final states accessible at the LHC are the decay into pairs of b quarks and τ leptons, both of which are experimentally challenging. In some cases, the exploitation of specific Higgs boson production modes allows to significantly increase the experimental sensitivity. One can also extend the search by looking for di-muon final states. This article gives an overview of the Higgs boson searches in these three fermionic final states at the ATLAS and CMS experiments, focusing on the most recent developments and results.


2014 ◽  
Vol 31 ◽  
pp. 1460287
Author(s):  
Romain Madar ◽  

The newly discovered boson was only observed in diboson final states. The measurement of the fermionic decay modes of this new particle is essential to establish its compatibility with the Standard Model Higgs boson. The two main final states accessible at the LHC are the decay into pairs of b quarks and τ leptons, both of which are experimentally challenging. In some cases, the exploitation of specific Higgs boson production modes allows to significantly increase the experimental sensitivity. One can also extend the search by looking for di-muon final states. This article gives an overview of the Higgs boson searches in these three fermionic final states at the ATLAS and CMS experiments, focusing on the most recent developments and results.


2014 ◽  
Vol 31 ◽  
pp. 1460303
Author(s):  
Jakob Salfeld-Nebgen

A search for the Standard Model Higgs Boson decaying into τ pairs is performed using events recorded by the CMS experiment at the LHC in 2011 and 2012. An excess of events is observed over a broad range of Higgs mass hypotheses, with a maximum local significance of 2.93 standard deviations at mH = 120 GeV. The excess is compatible with the presence of a standard-model Higgs boson of mass 125 GeV/c2.


2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
E. Cortina Gil ◽  
◽  
A. Kleimenova ◽  
E. Minucci ◽  
S. Padolski ◽  
...  

Abstract The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 109 tagged π0 mesons from K+ → π+π0(γ), searching for the decay of the π0 to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4.4 × 10−9 is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay K+ → π+X, where X is a particle escaping detection with mass in the range 0.110–0.155 GeV/c2 and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming X to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.


2021 ◽  
Vol 812 ◽  
pp. 135980
Author(s):  
G. Aad ◽  
B. Abbott ◽  
D.C. Abbott ◽  
A. Abed Abud ◽  
K. Abeling ◽  
...  

2001 ◽  
Vol 508 (3-4) ◽  
pp. 225-236 ◽  
Author(s):  
M. Acciarri ◽  
P. Achard ◽  
O. Adriani ◽  
M. Aguilar-Benitez ◽  
J. Alcaraz ◽  
...  

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