Probing the Lightest New Gauge Boson BH in the Littlest Higgs Model via Processes γγ→f■B_H at ILC

The neutral gauge boson BH with the mass of hundreds GeV is the lightest particle predicted by the littlest Higgs （LH） model, and such particle should be the first signal of the LH model at the planed ILC if it exists indeed. In this paper, we study some processes of the BH production associated with the fermion pair at the ILC, i.e., γγ→ ff^- BH. The studies show that the most promising processes to detect BH amongγγ→ ff^- BH are γγ→ l＇^＋l＇^-BH （l＇ = e,μ）, and they can produce the sufficient signals in most parameter space preferred by the electroweak precision data at the ILC. On the other hand, the signal produced via the certain BH decay modes is typical and such signal can be easily identified from the SM background. Therefore, BH, the lightest gauge boson in the LH model, would be detectable at the photon collider realized at the ILC.

Production of the new gauge boson BH via e^-y collision in the littlest Higgs model

The lightest new gauge boson BH with mass of hundreds GeV is predicted in the littlest Higgs model. BH should be accessible in the planned ILC and the observation of such particle can strongly support the littlest Higgs model. The realization of 7Y and e^-γ collisions would open a wider window to probe BH. In this paper, we study the new gauge boson BH production processes e^-γ→e^-BH and e^-γ→e^-BH at the ILC. Our results show that the production cross section of the process e^-γ→e^-BH is less than 0.1 fb in most parameter spaces allowed by the electroweak precision data while the cross section of the process e^-γ→e^-BH can be over one fb in the favorable parameter spaces. With the high luminosity, the enough typical signals could be produced via e^-γ→e^-BH. Because the final electron and photon beams can be easily identified and the signal can be easily distinguished from the backgrounds produced by Z and H decaying, e^-γ→e^-BH is a promising process to probe BH.

Associated productions of the new gauge boson B_H in the Littlest Higgs model with a SM gauge boson via e^+e^- collision

With the high energy and luminosity, the planned ILC has the considerable capability to probe the new heavy particles predicted by the new physics models. In this paper, we study the potential to discover the lightest new gauge boson BH of the Littlest Higgs model via the processes e^＋e^- →γ（Z）BH at the ILC. The results show that the production rates of these two processes are large enough to detect BH in a wide range of the parameter spaces, specially for the process e^＋e^- →γ TBH. Furthermore, there exist some decay modes for BH which can provide the typical signal and clean backgrounds. Therefore, the new gauge boson BH should be observable via these production processes with the running of the ILC if it exist.

New gauge forces beyond the standard model

In this work we investigate the minimal and next to minimal new gauge forces beyond standard model by constructing the corresponding electroweak chiral Lagrangians. Some phenomenological constraints from the mass differences in the K^0-^-K^0,Bd^0-^-Bd^0,Bs^0-^-Bs^0 systems and the corresponding CP violation parameter are discussed.

A Short Note on a Differential-Difference Gauge Transformation and a New Spectral Problem

We show that a class of spectral problems are related to the spectral problem of the Volterra lattice through a gauge transformation. The transformation is given. We hope that our discussion can draw attention to the study of gauge transformation theory of differential-difference integrable systems.

SU(3) Simple Group Model and New Z' Properties in Future Linear Colliders

In the SU（3） simple group model, the new neutral gauge boson Z＇ couples to pairs of SM fermions with couplings fixed in terms of the SM gauge couplings and depending only on the choice of the fermion embedding. In this paper, we calculate the contributions of this new particle to the processes e^＋e^-→l^＋l^-, bb^-, and cc^- and study the possibility of detecting this new particle via these processes in the future high-energy linear e^＋e^- collider（LC） experiments with √s= 500 GeV and ￡int= 340 fb^-1. We find that the new gauge boson Z＇ is most sensitive to the process e^＋e^-→b^＋b^-. As long as Mz,≤2 TeV , the absolute values of the relative correction parameter are larger than 5%. We calculate the forward-backward asymmetries and left-right asymmetries for the process e^＋e^-→c^＋c^-, with both the universal and anomaly-free fermion embeddings. Bounds on Z＇ masses are also estimated within 95% confidence level.

One-Loop Effects of Non-Universal Gauge Boson Z' in Top Quark Pair Production at LHC in TC2 Model

The topcolor-assisted technicolor model （TC2） predicts a non-universal Z′ gauge boson, which couples to the third generation fermions with enhanced strength. We study the effects of this non-universal gauge boson on the cross section and spin correlation of top quark pair production through the process gg → tt at the LHC. We find that the total cross section and the spin correlation can be reduced by-4.7% and -1.4% respectively in the allowed parameter space.

Single Production of Charged Gauge Boson W_H^-from Left-Right Twin Higgs Model in Association with Top Quark at LHC

The twin Higgs mechanism has recently been proposed to solve the little hierarchy problem. In the context of the left-right twin Higgs （LRTH） model, we discuss single production of the new charged gauge boson WH^- , which is predicted by the left-right twin Higgs model, in association with top quark at the CERN Large Hadron Collider （LHC）. It is found that, for a typical nonzero value of mass mixing parameter M = 150 GeV in the LRTH model, the production cross section is in the range of 3 ×10^-2 - 6.07×10^3 fb at the LHC. As long as the WH^- is not too heavy, the possible signatures of the heavy charged gauge boson might be detected at the LHC experiments.

Littlest Higgs Model and Higgs Boson Associated Production with Top Quark Pair at High Energy Linear e^＋e^- Collider

In the parameter space allowed by the electroweak precision measurement data, we consider the contributions of the new particles predicted by the littlest Higga model to the Higgs hoson associated production with top quark pair in the future high energy linear e^＋e^- collider （ILU）. We find that the contributions mainly come from the new gauge bosons ZH and BH. For reasonable values of the free parameters, the absolute value of the relative correction parameter δσ/σ^SM can be signiticanly large, which might be observed in the future ILU experiment with √S = 800 GeV.

Probing Topcolor-Assisted Technicolor Models from Like-Sign Γ Pair Production in rγ Collisions

We consider the contributions of the extra gauge boson Z＇ to the like sign ^- production processes e-＇γ→e＋（μ＋）τ-τ-, induced by the tree-level flavor changing interactions. Since these rare production are far below the observable level in the Standard Model and other popular new physics models such as the minimal supersymmetric model, we find that, in the topcolor-assisted technicolor models, the Z＇ can give significant contributions to these processes, and with reasonable values of the parameters, the cross section cr can reach several tens of tb and may be detected at the eγ collisions.

Searches for new neutral gauge boson at the Tevatron and LHC in the left-right twin Higgs model

In the framework of the left-right twin Higgs （LRTH） model, we study the possibilities to detect the new Z＇ boson at the Tevatron and LHC. First, using pp collision data collected by the DO and CDF II detectors, we find that the LRTH Z＇ boson is excluded with masses below 940 GeV. Then we search for signatures of the Z＇ boson at the LHC from the analysis of some distributions for pp --＊ It＋g- ＋ X, such as the number of events, the differential cross section of the dimuon invariant mass, the distributions of the transverse momentum and the forward-backward charge asymmetry. We do our calculation for two typical values of the LHC center of mass energy （7 and 14 TeV）. The numerical results show that, by applying convenient cuts on some of the observables, the dimuon invariant mass and final particle PT distributions can reveal the presence of the heavy neutral gauge boson Z＇ contribution in the LRTH model.

A multi-charged particle model with local U(1)_(μ-τ) to explain muon g-2,flavor physics,and possible collider signature

We consider a model with multi-charged particles,including vector-like fermions,and a charged scalar under a local U(1)_(μ−τ) symmetry.We search for an allowed parameter region explaining muon anomalous magnetic moment(muon g−2)and b→sℓ^(+)ℓ^(−) anomalies,satisfying constraints from the lepton flavor violations,Z boson decays,meson anti-meson mixing,and collider experiments.Via numerical analysis,we explore the typical size of the muon g−2 and Wilson coefficients to explain the b→sℓ^(+)ℓ^(−) anomalies in our model when all other experimental constraints are satisfied.Subsequently,we discuss the collider physics of the multicharged vectorlike fermions,considering a number of benchmark points in the allowed parameter space.

X(16.7) as the solution of the NuTeV anomaly

A recent experimental study of excited8 Be decay to its ground state revealed an anomaly in the angular distribution of the final states. This exceptional result is attributed to a new vector gauge boson X（16.7）. We study the significance of this new boson, especially its effect in anomalies observed in long-lasting experimental measurements.By comparing the discrepancies between the Standard Model predictions and the experimental results, we find the values and regions of the couplings of X（16.7） to the muon and muon neutrino. In this work, we find that the newly observed boson X（16.7） may be the solution of both the Nu Te V anomaly and the（g-2）μ puzzle.

Signals of the littlest Higgs model with T-parity at eγ and ep collisions

The littlest Higgs model with T-parity predicts the existence of the neutral, weakly interacting, new gauge boson BH, which can be seen as an attractive dark matter candidate. We study production of the new gauge boson BH via ey and ep collisions. We find that BH can be abundantly produced via the subprocesses e^-T→ L^-BH and γq→BHQ, which might give rise to characteristic signals. Some discussions about the SM backgrounds for this kind of signals are also given.

Search for dark matter production in association with the Z′ boson at the LHC in pp collisions at √s=8 TeV using Monte Carlo simulations

This analysis evaluates the possibility of the search for Dark Matter(DM)particles using events with a Zf heavy gauge boson and a large missing transverse momentum at the Large Hadron Collider(LHC).We consider the muonic decay of Z'.The analyzed Monte Carlo samples were the Open simulated files produced by the Compact Muon Solenoid(CMS)collaboration for proton-proton collisions,corresponding to an integrated luminosity of the LHC run-I with 19.7 fb^(-1) at √s=8 TeV.Two scenarios,namely a simplified benchmark scenario,called Dark Higgs,and the effective field theory(EFT)formalism,were used for interpretations.Limits were set on Z′,dark matter masses,and the cutoff scale of the EFT.