Related papers: Electroweak and Dark Matter Constraints on a Z' in…
We present the constraints on the parameter space of the Lee-Wick Standard Model coming from electroweak precision observables. The model predicts a large positive S and a negative T. We show that it is possible to find some regions in…
We compute the bounds on the dark matter (DM) annihilation cross section using the most recent Cosmic Microwave Background measurements from WMAP9, SPT'11 and ACT'10. We consider DM with mass in the MeV-TeV range annihilating 100% into…
We study electroweak scale Dark Matter (DM) whose interactions with baryonic matter are mediated by a heavy anomalous $Z'$. We emphasize that when the DM is a Majorana particle, its low-velocity annihilations are dominated by loop…
Dedicated underground experiments searching for dark matter have little sensitivity to GeV and sub-GeV masses of dark matter particles. We show that the decay of B mesons to K(K^*) and missing energy in the final state can be an efficient…
We consider the Z'/Z mass hierarchy in a supersymmetric model in which the U(1)' is broken in a secluded sector coupled to the ordinary sector only by gauge and possibly soft terms. A large mass hierarchy can be achieved while maintaining…
I review constraints on the Standard Model (SM) Higgs boson from high energy electroweak (EW) precision data. The same data set also strongly limits various mixing effects of hypothetical extra neutral gauge bosons (Z') with the ordinary Z.…
Recent experimental results in direct dark matter detection may be interpreted in terms of a dark matter particle of mass around 10 GeV/c^2. We show that the required scenario can be realized with a new dark matter particle charged under an…
The U(1)' symmetry associated with a possible heavy Z' would have profound implications for particle physics and cosmology. The motivations for such particles in various extensions of the standard model, possible ranges for their masses and…
The new observation of CDMS II favors low mass WIMPs. Taking the CDMS II new results as inputs, we consider a SM singlet: the darkon as the dark matter candidate, which can be either scalar, fermion or vector. It is found that the simplest…
We show that a Z' with suppressed couplings to the electron compared to the Z-boson, with couplings to the b-quark, and with a mass close to the mass of the Z-boson, provides an excellent fit to forward-backward asymmetry of the b-quark and…
Results from the global Standard Model fit to electroweak precision data, including newest Tevatron measurements, are reviewed and discussed. The complete fit using also the constraints from the direct Higgs boson searches yields an upper…
We study perturbative unitarity constraints on general W' models by considering the high energy behavior of fermion scattering into gauge bosons. In most cases we survey, a Z' boson with a comparable mass must be present for the theory to…
We study the type-II first-order electroweak phase transition and dark matter (DM) phenomenology in both real and complex singlet extensions of SM. In the real singlet extension with a $\mathbb{Z}_2$ symmetry, we show that the parameter…
Indirect precision data are used to constrain the masses of possible extra Z^prime bosons and their mixings with the ordinary Z. We study a variety of Z^prime bosons as they appear in E_6 and left-right unification models, the sequential Z…
The electroweak symmetry may be broken by a composite Higgs which arises naturally as a bound state of the top quark if the standard model gauge fields and fermions propagate in extra dimenions. The top quark mass and the Higgs mass can be…
Recent null results from LHC8 SUSY searches along with the discovery of a SM-like Higgs boson with mass m(h) ~ 125.5 GeV indicates sparticle masses in the TeV range, causing tension with conventional measures of electroweak fine-tuning. We…
We consider a U(1)$_X$ gauge symmetry extension of the Standard Model (SM) with a $Z^\prime$-portal Majorana fermion dark matter that allows for a relatively light gauge boson $Z^\prime$ with mass of 10 MeV$-$ a few GeV and a much heavier…
Motivated by the dark matter and the baryon asymmetry problems, we analyse a complex singlet extension of the Standard Model (SM) with a Z2 symmetry (which provides a dark matter candidate). After a detailed two-loop calculation of the…
The idea that dark-matter interactions with Standard-Model particles may be mediated by new bosons with masses in the MeV-to-GeV range took off several years ago. Constraints on such models were soon calculated based on older measurements.…
Inspired by the phenomenological constraints, LHC supersymmetry and Higgs searches, dark matter search as well as string model building, we propose the electroweak supersymmetry around the electroweak scale: the squarks and/or gluinos are…