35611437
Top quark forward-backward asymmetry in the little Higgs model
A sizable difference in top quark pair forward backward asymmetry (AFB) is observed at Tevatron. The discrepancy triggers many new physics beyond the standard model (SM) and then constrains the parameter spaces in them. In this article we calculate the AFB of the top-pair production at Tevatron up to next to leading order (NLO) in the little Higgs model (LHM). We find that the contribution of ZH can be large enough to make up the gap between SM prediction and experimental data. Then, the parameter space for the couplings between ZH and quarks are constrained. Thus, this model can fulfill the experimental data, both in AFB and in cross section.
16933147
Possible S-wave Bound-States of Two Pseudoscalar Mesons
AbstractUsing the potentials derived from vector-meson-exchanges, the KK¯, DK, BK¯, DD¯,BB¯, BD, DK¯ , BKand BD¯ systems are studied. Possible S-wave bound-states of twopseudoscalar mesons are discussed. We ﬁnd that systems of DB, DD¯, BB¯ and DKwithisospin 0 are likely to form S-wavebound states via strong interactionswhile the othersareunlikely to be bound by the strong interaction sector alone. With the Coulomb potential,the K + K − system can form an atomic bound state - the kaonium. The inﬂuence of theone-meson-exchange potential on the ground state energy of the kaonium and its decaywidths to ππand πηare evaluated. 1 Introduction Since the 1970’s, the possible existence of the nuclear-like bound states of mesons has beenone of the interesting subjects in hadron physics. Some hardrons such as the ψ(4040) [1],η(1440) [2], f 1 (1420) [3], f J (1720) [4], and the f 0 (980) and a 0 (980) [5, 6, 7, 8] were explainedas the nuclear-like bound states of mesons. To¨rnqvist [9] argued that the one-pion-exchangepotential is likely to form a few states composed of two ground-state mesons. In 2003 the BelleCollaboration reported a new narrow charmonium state at 3872±0.6(stat)±0.5(syst) MeVand with a width <2.3MeV(95% C.L.), which has been conﬁrmed by several experiments[10, 11, 12, 13]. Almost immediately, To¨rnqvist [14] claimed that this state is the one hepredicted long ago. Indeed the proximity of the X to D
118558798
A possible NN*(1440) quasi-molecular state
Inspired by the recent observation of a narrow resonance-like structure around 2360 MeV in the pn → dπ0π0 cross section, the possibility of forming a NN*(1440) quasi-molecular state is investigated by using a meson exchange model in which the π, σ, ρ and ω exchanges in t- and u-channels are considered. By adopting the coupling constants extracted from the relevant NN scattering and N*(1440) decay data, it is found that a deuteron-like quasi-molecular state of NN*(1440) with a binding energy in the range of 2 ∼ 67 MeV can be formed. Therefore, it is speculated that the observed structure around 2360 MeV might be or may have a large component of the NN*(1440) quasi-molecular state.
127622395
Ward identity of two-loop diagrams in SUSY
118481043
The D0 Dimuon Charge Asymmetry and Baryon Asymmetry of the Universe
The D0 collaboration has reported a 3.2 \sigma deviation from the Standard Model (SM) prediction in the like-sign dimuon charge asymmetry. New physics beyond the SM in B_s - \bar B_s mixing is needed to explain the data. In this paper, we investigate the possible extension of the SM with one generation color-triplet charged scalar as well as three generation Majorana fermions. We study the implications of the model on the D0's dimuon charge asymmetry as well as matter anti-matter asymmetry of the Universe.
14103118
Integrable electron model with correlated hopping and quantum supersymmetry
Abstract We give the q -deformed analogue of a recently introduced electron model which generalizes the Hubbard model with additional correlated hopping terms and electron pair hopping. The model contains two independent parameters and is invariant with respect to the quantum superalgebra U q ( gl (2|1)). It is shown to be integrable in one dimension by means of the quantum inverse scattering method.
19788205
CP-violating phenomenology of flavor conserving two Higgs doublet models
We analyze the constraints on CP-violating, flavor conserving two Higgs doublet models implied by measurements of Higgs boson properties at the Large Hadron Collider (LHC) and by the nonobservation of permanent electric dipole moments (EDMs) of molecules, atoms, and neutrons. We find that the LHC and EDM constraints are largely complementary, with the LHC studies constraining the mixing between the neutral CP-even states and the EDMs probing the effect of mixing between the CP-even and CP-odd scalars. Presently, the most stringent constraints are implied by the nonobservation of the ThO molecule EDM signal. Future improvements in the sensitivity of neutron and diamagnetic atom EDM searches could yield competitive or even more severe constraints. We analyze the quantitative impact of hadronic and nuclear theory uncertainties on the interpretation of the latter systems and conclude that these uncertainties cloud the impact of projected improvements in the corresponding experimental sensitivities.
119262345
Perturbative unitarity constraints on general W' models and collider implications
We study perturbative unitarity constraints on general W 0 models by considering the high energy behavior of fermion scattering into gauge bosons. In most cases we survey, a Z 0 boson with a comparable mass must be present for the theory to be consistent, with xed couplings to the standard model gauge bosons and fermions. Applying these results to a class of W 0 models which explains the top quark forward{backward asymmetry observed at the Tevatron, we nd that a Z 0 must exist with a mass below 7 8 TeV and sizable coupling to the light quarks. While such a Z 0 is strongly constrained by existing experiments, we show that the LHC can explore the entire mass range up to the unitarity limit. We also show how it is possible, by raising the Z 0 mass consistent with unitarity, to explain the CDF Wjj excess in terms of a light W 0 , without generating an excess in Zjj events.
53520209
Pair production of 125 GeV Higgs boson in the SM extension with color-octet scalars at the LHC
A bstractAlthough the Higgs boson mass and single production rate have been determined more or less precisely, its other properties may deviate significantly from its predictions in the standard model (SM) due to the uncertainty of Higgs data. In this work we study the Higgs pair production at the LHC in the Manohar-Wise model, which extends the SM by one family of color-octet and isospin-doublet scalars. We first scanned over the parameter space of the Manohar-Wise model considering experimental constraints and performed fits in the model to the latest Higgs data by using the ATLAS and CMS data separately. Then we calculated the Higgs pair production rate and investigated the potential of its discovery at the LHC14. We conclude that: (i) Under current constrains including Higgs data after Run I of the LHC, the cross section of Higgs pair production in the Manohar-Wise model can be enhanced up to even 103 times prediction in the SM. (ii) Moreover, the sizable enhancement comes from the contributions of the CP-odd color-octet scalar $ S_I^A $. For lighter scalar $ S_I^A $ and larger values of |λI|, the cross section of Higgs pair production can be much larger. (iii) After running again of LHC at 14 TeV, most of the parameter spaces in the Manohar-Wise model can be test. For an integrated luminosity of 100 fb−1 at the LHC14, when the normalized ratio R = 10, the process of Higgs pair production can be detected.