342 research outputs found

### Is an axizilla possible for di-photon resonance?

Heavy axion-like particles, called axizillas, are simple extensions of the
standard model(SM). An axizilla is required not to couple to the quarks,
leptons, and Brout-Englert-Higgs doublets of the SM, but couple to the gauge
anomalies of the $W^\pm, Z$ and photon. It is possible to have its branching
ratios(BRs) to two photons greater than 10% and to two $Z$'s less than 10%. To
have a (production cross section)$\cdot$(BR to di-photons) at a
$10^{-38}\,\textrm{cm}^2$ level, a TeV scale heavy quark $Q$ is required for
the gluon--quark fusion process. The decay of $Q$ to axizilla plus quark, and
the subsequent decay of the axizilla to two photons can be fitted at the
required level of $10^{-38}\,\textrm{cm}^2$.Comment: 9 pages of latex file with 3 figure

### R-parity from string compactification

In this paper, we embed the $\Z_{4R}$ parity as a discrete subgroup of a
global symmetry \UoR\,obtained from $\Z_{12-I}$ compactification of heterotic
string \EE8. A part of \UoR\,transformation is the shift of the anticommuting
variable $\vartheta$ to $e^{i\alpha}\vartheta$ which necessarily incoorporate
the transformation of internal space coordinate. Out of six internal spaces, we
identify three U(1)'s whose charges are denoted as $Q_{18},Q_{20}$, and
$Q_{22}$. The \UoR~is defined as \UEE$\times$\UKK~where \UEE~is the part from
\EE8 and \UKK~is the part generated by $Q_{18},Q_{20}$, and $Q_{22}$. We
propose a method to define a \UoR~direction. The needed vacuum expectation
values for breaking gauge U(1)'s except U(1)$_Y$ of the standard model carry
\UoR~charge 4 modulo 4 such that \UoR~is broken down to $\Z_{4R}$ at the grand
unification scale. $\Z_{4R}$ is broken to $\Z_{2R}$ between the intermediate
(\sim 10^{11\,}\gev) and the electroweak scales (100\,\gev\sim 1\,\tev).
The conditions we impose are proton longevity, a large top quark mass, and
acceptable magnitudes for the $\mu$ term and neutrino masses.Comment: 21 pages with 3 figure

### Self-tuning solutions of the cosmological constant

I briefly review the cosmological constant problem and attempts toward its
solution, and present the first nontrivial example for the self-tuning
mechanism with a $1/H^2$ term with the antisymmetric field strength $H_{MNPQ}$
in a 5D RS-II setup.Comment: Latex file of 9 pages. Talk presented at SUSY'01, Dubna, Russia,
11--17 June 200

### Towards unity of families: anti-SU(7) from Z(12-I) orbifold compactification

The problem of families, "Why are there three families of fermions?", is a
long awaited question to be answered within a reasonable framework. We propose
anti-SU($N$) groups for the unification of families in grand unification (GUT)
groups, where the separation of color and weak gauge groups in the GUT is
achieved by antisymmetric tensor Brout-Englert-Higgs boson instead of an
adjoint representation. Theories of anti-SU($N$)'s are proposed for the
unification of families. The minimal model is found as \antiSD \, GUT with the
fermion representation [3]+2[2]+8[\bar-1]. We present an example in a Z(12-I)
orbifold compactification, where the missing partner mechanism is also
realized.Comment: 24 page

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