1203139
Gauge coupling unification in a 6D SO(10) orbifold GUT
Abstract We consider the gauge coupling running in a six-dimensional SO ( 10 ) orbifold GUT model. The bulk gauge symmetry is broken down to the standard model gauge group with an extra U ( 1 ) X by orbifold boundary conditions and the extra U ( 1 ) X is further broken through the U ( 1 ) B – L breaking with bulk hyper multiplets. We obtain the corrections of Kaluza–Klein massive modes to the running of the gauge couplings and discuss their implication to the successful gauge coupling unification.
204934408
Gravity in the Einstein-Gauss-Bonnet Theory with the Randall-Sundrum Background
We obtain the full 5D graviton propagator in the Randall-Sundrum model with the Gauss-Bonnet interaction. From the decomposition of the graviton propagator on the brane, we show that localization of gravity arises in the presence of the Gauss-Bonnet term. We also obtain the metric perturbation for observers on the brane with considering the brane bending and compute the amplitude of one massless graviton exchange. For the positive definite amplitude or no ghost states, the sign of the Gauss-Bonnet coefficient should be negative in our convention, which is compatible with string amplitude computations. In that case, the ghost-free condition is sufficient for obtaining the Newtonian gravity. For a vanishing Gauss-Bonnet coefficient, the brane bending allows us to reproduce the correct graviton polarizations for the effective 4D Einstein gravity.
119248157
Vector Higgs-portal dark matter and the invisible Higgs
The Higgs sector of the Standard Model offers a unique probe of the hidden sector. In this work, we explore the possibility of renormalizable Higgs couplings to the hidden sector vector fields which can constitute dark matter (DM). Abelian gauge sectors with minimal field content, necessary to render the gauge fields massive, have a natural Z2 parity. This symmetry ensures stability of the vector fields making them viable dark matter candidates, while evading the usual electroweak
14096456
Wave function of the radion in the brane background with a massless scalar field and a self-tuning problem
We consider flat solutions in a brane world model with a massless scalar field appearing in 5D ${H}_{\mathrm{MNPQ}}^{2}.$ Since those solutions have naked bulk singularities or are such that the 4D Planck mass is divergent, we should have a compact extra dimension, the size of which is then fixed by brane tension(s) and the bulk cosmological constant. By inspecting scalar perturbations around the flat solutions, we find that there is no zero mode for the radion and radion modes have only positive masses. This result confirms the fact that the radius of the extra dimension cannot be adjusted independently of the parameters of the model, and thus that the model considered does not solve the problems encountered in other approaches to the self-tuning of the cosmological constant.
119217517
U(1)R mediation from the flux compactification in six dimensions
We consider a supersymmetric completion of codimension‐two branes with nonzero tension in a 6D gauged supergravity. As a consequence, we obtain the football solution with 4D Minkowski space as a new supersymmetric background that preserves 4D N = 1 SUSY. In the presence of brane multiplets, we derive the 4D effective supergravity action for the football background and show that the remaining modulus can be stabilized by a bulk non‐perturbative correction with brane uplifting potentials at a zero vacuum energy. We find that the U(1)R mediation can be a dominant source of SUSY breaking for a brane scalar with nonzero R charge.
11210523
TeV scale 5D SU(3)W unification and the fixed point anomaly cancellation with chiral split multiplets
A possibility of 5D gauge unification of SU(2)L × U(1)Y in SU(3)W is examined. The orbifold compactification allows fixed points where SU(2)L × U(1)Y representations can be assigned. We present a few possibilities which give long proton lifetime, top-bottom mass hierarchy from geometry, and reasonable neutrino masses. In general, these chiral models can lead to fixed point anomalies. We can show easily, due to the simplicity of the model, that these anomalies are cancelled by the relevant Chern-Simons terms for all the models we consider. It is also shown that the fixed point U(1)-graviton-graviton anomaly cancels without the help from the Chern-Simons term. Hence, we conjecture that the fixed point anomalies can be cancelled if the effective 4D theory is made anomaly free by locating chiral fermions at the fixed points.
118552297
Muon g − 2 anomaly and dark leptonic gauge boson
One of the major motivations to search for a dark gauge boson of MeV-GeV scale is the long-standing muon g-2 anomaly. Because of active searches such as fixed target experiments and rare meson decays, the muon g-2 favored parameter region has been rapidly reduced. With the most recent data, it is practically excluded now in the popular dark photon model. We overview the issue and investigate a potentially alternative model based on the gauged lepton number or U(1)_L, which is under different experimental constraints.
31015901
Muon anomaly and dark parity violation.
The muon anomalous magnetic moment exhibits a 3.6σ discrepancy between experiment and theory. One explanation requires the existence of a light vector boson, Z(d) (the dark Z), with mass 10-500 MeV that couples weakly to the electromagnetic current through kinetic mixing. Support for such a solution also comes from astrophysics conjectures regarding the utility of a U(1)(d) gauge symmetry in the dark matter sector. In that scenario, we show that mass mixing between the Z(d) and ordinary Z boson introduces a new source of "dark" parity violation, which is potentially observable in atomic and polarized electron scattering experiments. Restrictive bounds on the mixing (m(Z(d))/m(Z))δ are found from existing atomic parity violation results, δ2<2×10(-5). Combined with future planned and proposed polarized electron scattering experiments, a sensitivity of δ2∼10(-6) is expected to be reached, thereby complementing direct searches for the Z(d) boson.
119255590
Lightest U-parity particle (LUP) dark matter
Abstract We suggest a U ( 1 ) ′ gauge symmetry as an alternative to the usual R -parity of supersymmetric standard models, showing that it can also work as a common source of stabilities of proton and dark matter in addition to other attractive features. The residual discrete symmetries of a single U ( 1 ) ′ can provide stabilities to both the MSSM sector (proton) and the hidden sector (new dark matter candidate, LUP). The LUP can expand the viability of many models such as R -parity violating models and gauge mediation models regarding dark matter issue.
119201717
Bound on Z' Mass from CDMS II in the Dark Left-Right Gauge Model II
With the recent possible signal of dark matter from the CDMS II experiment, the Z{sup '} mass of a new version of the dark left-right gauge model (DLRM II) is predicted to be at around a TeV. As such, it has an excellent discovery prognosis at the operating Large Hadron Collider.
16281369
Common gauge origin of discrete symmetries in observable sector and hidden sector
An extra Abelian gauge symmetry is motivated in many new physics models in both supersymmetric and nonsupersymmetric cases. Such a new gauge symmetry may interact with both the observable sector and the hidden sector. We systematically investigate the most general residual discrete symmetries in both sectors from a common Abelian gauge symmetry. Those discrete symmetries can ensure the stability of the proton and the dark matter candidate. A hidden sector dark matter candidate (lightest U-parity particle or LUP) interacts with the standard model fields through the gauge boson Z' which may selectively couple to quarks or leptons only. We make a comment on the implications of the discrete symmetry and the leptonically coupling dark matter candidate, which has been highlighted recently due to the possibility of the simultaneous explanation of the DAMA and the PAMELA results. We also show how to construct the most general U(1) charges for a given discrete symmetry, and discuss the relation between the U(1) gauge symmetry and R-parity.