Probing a Very NarrowZ′Boson with CDF and D0 Data

Abstract

The CDF and D0 data of nearly 475 pb ÿ1 in the dilepton channel is used to probe a recent class of models, Stueckelberg extensions of the standard model (StSM), which predict a Z 0 boson whose mass is of topological origin with a very narrow decay width. A Drell-Yan analysis for dilepton production via this Z 0 shows that the current data put constraints on the parameter space of the StSM. With a total integrated luminosity of 8 fb ÿ1 , the very narrow Z 0 can be discovered up to a mass of about 600 GeV. The StSM Z 0 will be very distinct since it can occur in the region where a Randall-Sundrum graviton is excluded.

Multicomponent dark matter in supersymmetric hidden sector extensions

“…Recently several particle physics models have been constructed that connect the standard model (SM) to hidden sectors and lead to massive narrow vector boson resonances as well as other signatures which can be detected at colliders [1,2,3]. The connection to the hidden sector arises via mass mixings and kinetic mixings [1,2,3,4,5,6] and via higher dimensional operators.…”

“…(2) we give a detailed description of the two models one of which is based on a U(1) X extension of the MSSM where U(1) X is a hidden sector gauge group with Dirac fermions in the hidden sector. This model allows for dark matter consisting of Dirac, Majorana, and spin zero particles.…”

“…The connection to the hidden sector arises via mass mixings and kinetic mixings [1,2,3,4,5,6] and via higher dimensional operators. Models with the above forms of communication between the sectors also have important implications for dark matter [7,3,6] (for a review see [8,9]).…”

“…(5) we give an analysis of event rates for the proposed models for CDMS-II and for XENON-100. We give the analysis within the framework of supergravity grand unified models [23,24] defined by the parameters m 0 , m 1/2 , A 0 , tan β, and sign(µ) with nonuniversalities (NUSUGRA) defined by δ 1,2,3 in the gaugino sector so that (3) C gaugino masses at the grand unified theory (GUT) scale are given bym i = m 1/2 (1 + δ i ) (i = 1, 2, 3) (see, e.g., [25] and references therein). We also discuss the possible new physics one might observe at the LHC (for a recent review see also [9]) and elsewhere for these models.…”

Can a millicharged dark matter particle emit an observable γ-ray line?

“…Constraints on the φ parameter from the Z mass and ρ-parameter values can be obtained following the approach of [13], leading to the bound tan φ 3 × 10 −2 , which justifies the approximation of small φ used in the following. Note that in the Stueckelberg and in the "just-so" cases, the millicharge must be fractional if by U(1) one means a real compact U(1) symmetry (rather than a R-symmetry), as considerations of quantum gravity/string theory require [14,15].…”