scholarly journals Anomaly cancellation and the gauge group of the Standard Model in NCG

1995 ◽  
Vol 364 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Enrique Alvarez ◽  
JoséM. Gracia-Bondía ◽  
C.P. Martín
2021 ◽  
Vol 81 (5) ◽  
Author(s):  
J. A. Aguilar-Saavedra ◽  
I. Lara ◽  
D. E. López-Fogliani ◽  
C. Muñoz

AbstractIn the $$\mu \nu $$ μ ν SSM, the presence of R-parity violating couplings involving right-handed (RH) neutrinos solves simultaneously the $$\mu $$ μ - and $$\nu $$ ν -problems. We explore extensions of the $$\mu \nu $$ μ ν SSM adding a $$U(1)'$$ U ( 1 ) ′ gauge group, which provides the RH neutrinos with a non-vanishing charge. In these models, dubbed U$$\mu \nu $$ μ ν SSM, the anomaly cancellation conditions impose the presence of exotic quarks in the spectrum that are vector-like under the standard model (SM) gauge group: either three pairs SU(2) quark singlets, or a pair of quark singlets together with a pair of quark doublets. Several singlets under the SM group can also be present, with the $$U(1)'$$ U ( 1 ) ′ charges making distinctions among them, and therefore allowing different types of couplings. Some of these singlets dynamically generate Majorana masses for the RH neutrinos, and others can be candidates for dark matter. The useful characteristics of models with $$U(1)'$$ U ( 1 ) ′ s are also present in U$$\mu \nu $$ μ ν SSM models: baryon-number-violating operators as well as explicit Majorana masses and $$\mu $$ μ terms are forbidden, and the domain wall problem is avoided. The phenomenology of U$$\mu \nu $$ μ ν SSM models is very rich. We analyze the experimental constraints on their parameter space, specially on the mass and mixing of the new $$Z'$$ Z ′ boson. In addition to the exotic quarks, which can hadronize inside the detector or decay producing SM particles, the U$$\mu \nu $$ μ ν SSM models can also have new signals such as decays of the $$Z'$$ Z ′ to sparticle pairs like right sneutrinos, charginos or neutralinos. Besides, $$Z'$$ Z ′ and Higgs mediated annihilations and interactions with the visible sector of WIMP dark matter particles, can also be present.


2019 ◽  
Vol 34 (35) ◽  
pp. 1950292
Author(s):  
Elmer Ramirez Barreto ◽  
David Romero Abad

In this work, we explore the possibility of fixing the number of new non-sequential chiral-type generations of fermions that could be added to the Standard Model by combining the condition that arise from the anomaly cancellation with the restriction in the number of flavors imposed by the QCD asymptotic freedom. We found that the maximum number of new generations is four, and this allows us, at the same time, to place limits for the electrical charges of quarks and leptons within an SM-like framework. Our result is compatible with the constraints involving new generations and their contributions to the oblique parameters S and T.


2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Priyotosh Bandyopadhyay ◽  
Saunak Dutta ◽  
Anirban Karan

AbstractThough various extensions of the Standard Model with higher gauge group predict the existence of leptoquarks, none of them has been observed yet at any of the colliders. In this paper, we study the prospect of several past and future $$e$$ e -$$p$$ p colliders like HERA, LHeC and FCC-he to detect them through radiation amplitude zero. We find that the leptoquarks showing zeros in the tree-level single-photon amplitudes at $$e$$ e -$$p$$ p collider lie within the complementary set of those exhibiting zeros at e-$$\gamma $$ γ collider. We present a PYTHIA-based analysis for HERA, LHeC and FCC-he (run II) to detect the leptoquarks with masses 70 GeV, 900 GeV and 1.5 TeV (2.0 TeV) respectively through radiation amplitude zero.


2021 ◽  
Vol 61 ◽  
pp. 1-16
Author(s):  
Daniele Corradetti ◽  

Recent papers contributed revitalizing the study of the exceptional Jordan algebra $\mathfrak{h}_{3}(\mathbb{O})$ in its relations with the true Standard Model gauge group $\mathrm{G}_{SM}$. The absence of complex representations of $\mathrm{F}_{4}$ does not allow $\Aut\left(\mathfrak{h}_{3}(\mathbb{O})\right)$ to be a candidate for any Grand Unified Theories, but the automorphisms of the complexification of this algebra, i.e., $\mathfrak{h}_{3}^{\mathbb{C}}(\mathbb{O})$, are isomorphic to the compact form of $\mathrm{E}_{6}$ and similar constructions lead to the gauge group of the minimal left-right symmetric extension of the Standard Model.


2007 ◽  
Vol 22 (21) ◽  
pp. 3669-3691 ◽  
Author(s):  
ERNESTO A. MATUTE

The standard electroweak model with Dirac neutrinos is extended by way of the principles of electroweak quark–lepton symmetry and weak topological-charge confinement to account for quark–lepton charge relations which, if not accidental, are indicative of charge structures. A mixing in quarks and leptons of underlying integer local charges with integer weak topological charges associated with an additive group Z3, fixed by the anomaly cancellation requirement, is discussed. It is found that the electroweak difference between topological quarks and leptons is the nonequivalence between the topological vacua of their weak field configurations, produced by a four-instanton which carries the topological charge, induces the universal fractional piece of charge distinguishing quarks from leptons, and breaks the underlying symmetry. The constituent quarks of the standard model appear as coming from topological quarks, via the weak four-instanton event. Dual transitions occur for leptons. It is shown that several other fundamental problems left open in the standard electroweak model with Dirac neutrinos are solved: the one-to-one correspondence between quark and lepton flavors, the existence of three generations, the conservation and ungauging of B-L, the electric charge quantization, and the confinement of fractional electric charges.


2006 ◽  
Vol 21 (06) ◽  
pp. 1261-1281 ◽  
Author(s):  
GOTTFRIED CURIO

We show how to construct supersymmetric three-generation models with gauge group and matter content of the Standard Model in the framework of non-simply-connected elliptically fibered Calabi–Yau manifolds Z. The elliptic fibration on a cover Calabi–Yau, where the model has six generations of SU(5) and the bundle is given via the spectral cover description, has a second section leading to the needed free involution. The relevant involution on the defining spectral data of the bundle is identified for a general Calabi–Yau of this type and invariant bundles are generally constructible.


2012 ◽  
Vol 27 (21) ◽  
pp. 1250117 ◽  
Author(s):  
FAYYAZUDDIN

A model for electroweak unification of quarks and leptons, in a gauge group SUC(3) × SU(4) × UX(1) is constructed. The model requires, three generations of quarks and leptons which are replicas (mirror) of the standard quarks and leptons. The gauge group SU(4) × UX(1) is broken in such a way so as to reproduce standard model and to generate heavy masses for the vector bosons [Formula: see text], the leptoquarks and mirror fermions. It is shown lower limit on mass scale of mirror fermions is [Formula: see text], E- being the lightest mirror fermion coupled to Z boson. As the universe expands, the heavy matter is decoupled at an early stage of expansion and may be a source of dark matter. Leptoquarks in the model connect the standard model and mirror fermions. Baryon genesis in our universe implies antibaryon genesis in mirror universe.


2005 ◽  
Vol 20 (18) ◽  
pp. 4241-4257 ◽  
Author(s):  
B. ANANTHANARAYAN ◽  
P. N. PANDITA

We consider supersymmetric SO(10) grand unification where the unified gauge group can break to the Standard Model gauge group through different chains. The breaking of SO(10) necessarily involves the reduction of the rank, and consequent generation of nonuniversal supersymmetry breaking scalar mass terms. We derive squark and slepton mass relations, taking into account these nonuniversal contributions to the sfermion masses, which can help distinguish between the different chains through which the SO(10) gauge group breaks to the Standard Model gauge group. We then study some implications of these nonuniversal supersymmetry breaking scalar masses for the low energy phenomenology.


2000 ◽  
Vol 15 (02) ◽  
pp. 265-282 ◽  
Author(s):  
GEORGE TRIANTAPHYLLOU

The existence of mirror fermions interacting strongly under a new gauge group and having masses near the electroweak scale has been recently proposed as a viable alternative to the standard-model Higgs mechanism. The main purpose of this work is to investigate which specific experimental signals are needed to clearly differentiate the mirror-fermion model from other new-physics models. In particular, the case is made for a future large lepton collider with c.o.m. energies of roughly 4 TeV or higher.


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