120520076
Soliton mass and discrete coupling constants in the quantized sine-Gordon model
The soliton mass in the quantized sine-Gordon model over the whole range of the coupling constant (g2 from 0 to 8 pi ) is evaluated by means of the Gaussian effective potential method. The analytical expression with numerical results is presented. The authors find that the coupling constant g can only take discrete values. A new kind of soliton linking g Phi =0 to g Phi = pi emerges at a set of special coupling constants g.
13049479
A new kind of constraints on renormalization schemes
We derive a new kind of physical constraints on the subtraction schemes for theories with massive particles in addition to the Ward identities for gauge symmetries. The momentum subtraction scheme fails this criterion. The decoupling of heavy fields is discussed in the context of Callan-Symanzik equations where all schemes (including MOM) lead to the same pattern of decoupling with inevitable discontinuities in beta function across heavy field thresholds. PACS number(s): 11.10.Gh; 11.10.Hi; 12.39.Hg
119670186
Padé Expansion and the Renormalization of Nucleon–Nucleon Scattering
The importance of imposing physical boundary conditions on the T-matrix to remove the nonperturbative renormalization prescription dependence is stressed and demonstrated in two diagonal channels 1P1 and 1D2, with the help of Pade expansion.
119099687
Pad\'e expansion and nucleon-nucleon scattering in coupled channels
Since the significant effective field theory (EFT) approach to nucleon systems[1, 2], there has been creating controversies about the consistent renormalization and EFT power counting in nonperturbative regime[3, 4]. The main difficulty is due to the nontrivial prescription dependence developed in nonperturbative regime, where some wisdoms about renormalization established within perturbative regimes cease to apply directly[5]. Therefore, the nonperturbative prescription dependence must be removed through imposing appropriate boundary conditions which are usually implemented through various forms of data fitting either explicitly or implicitly[6, 7, 8, 9, 10, 11, 12, 13]. In more recent literature, nonperturbative counter terms, or equivalently, nonperturbative parametrization of the renormalization prescription has been the main focus[14, 15]. That is, due to the difficulty in treating the issues in nonperturbative regimes, the key issue is to find more efficient parametrization of nonperturbative prescription. In this regard, we have performed an analysis and treatment of the nonperturbative prescription dependence basing on Padé approximant of an important nonperturbative factor of T -matrix for nucleon-nucleon (NN) scattering in uncoupled channles[16, 17, 18]. In this report, we will extend our analysis to coupled channels. Some general theoretical and technical issues associated with coupled channels will be addressed first, then we will illustrate our method in D3−G3. The object under consideration is the T -matrix for nucleon-nucleon scattering processes at low energies. According to Weinberg’s proposal[19], this T -matrix should be solved from Lippmann-Schwinger (LS) equation with the potential to be systematically constructed using χPT as the low energy effective theory of QCD. For coupled channels, such LSE’s read,
125789702
A nonperturbative scenario for EFT renormalization
15620058
Quantum field theory can be UV finite if it is taken as effective one
This is a further explanation of a new and simple renormalization approach recently proposed by the author (hep-th/9708104, Ref. [1], that is somewhat sketchy) for any ordinary QFT (whether renormalizable or not) in any spacetime dimension. We discussed the physical motivations of the new approach and its efficiency when compared to the existent renormalization approaches. Some other important issues related are briefly touched.
118624920
Rare Z-decay into light CP-odd Higgs bosons: a comparative study in different new physics models
Various new physics models predict a light CP-odd Higgs boson (labeled as a) and open up new decay modes for Z-boson, such as $ Z \to \bar{f}fa $, Z → aγ and Z → aaa, which could be explored at the GigaZ option of the ILC. In this work we investigate these rare decays in several new physics models, namely the type-II two Higgs doublet model (type-II 2HDM), the lepton-specific two Higgs doublet model (L2HDM), the nearly minimal supersymetric standard model (nMSSM) and the next-to-minimal supersymmetric standard model (NMSSM). We find that in the parameter space allowed by current experiments, the branching ratios can reach 10−4 for $ Z \to \bar{f}fa (f = b,\tau)$, 10−9 for Z → aγ and 10−3 for Z → aaa, which implies that the decays $ Z \to \bar{f}fa $ and Z → aaa may be accessible at the GigaZ option. Moreover, since different models predict different patterns of the branching ratios, the measurement of these rare decays at the GigaZ may be utilized to distinguish the models.
118656803
Realistic flipped SU(5) from orbifold SO(10)
We propose a realistic flipped SU(5) model derived from a five-dimensional orbifold SO(10) model. The Standard Model (SM) fermion masses and mixings are explained by combining the traditional Froggatt-Nielsen mechanism with the five-dimensional wave function profiles of the SM fermions. Employing tree-level spontaneous R-symmetry breaking in the hidden sector and extra(ordinary) gauge mediation, we obtain realistic supersymmetry breaking soft mass terms with non-vanishing gaugino masses. Including the messenger fields at the intermediate scale and Kaluza-Klein states at the compactification scale, we study gauge coupling unification. We show that the SO(10) unified gauge coupling is very strong and the unification scale can be much higher than the compactification scale. We briefly discuss proton decay as well.
123678213
Rare decays of the top quark in the technicolour model with a massless scalar doublet
The rare decays induced through loop processes are calculated in a minimal technicolour model (MTC) with a massless weak doublet recently presented by Carone and Georgi. We find that these new contributions can enhance the standard model branching fractions by as much as three to four orders of magnitude, i.e. , , for favourable values of the parameters. This might provide a unique window to detect the virtual effects of technipions in MTC theory.
36032236
Lepton flavor violating Z-decays in supersymmetric seesaw model
Abstract.In the supersymmetric seesaw model, large flavor mixings of sleptons induce the lepton flavor violating (LFV) interactions $\ell_I \bar\ell_J V$ ($V = \gamma, Z$), which give rise to various LFV processes. In this work we examine the LFV decays $Z\to\ell_I \bar\ell_J$. Subject to the constraints from the existing neutrino oscillation data and the experimental bounds on the decays $\ell_J\to\ell_I\gamma$, these LFV Z-decays are found to be sizable, and among them the largest-rate channel $Z\to \tau \bar{\mu}$ can occur with a branching ratio of 10-8 and may be accessible at the LHC or GigaZ experiment.
118655875
Split-SUSY dark matter in light of direct detection limits
We examine the present and future XENON limits on the neutralino dark matter in split supersymmetry (split-SUSY). Through a scan over the parameter space under the current constraints from collider experiments and the WMAP measurement of the dark matter relic density, we find that in the allowed parameter space a large part has been excluded by the present XENON100 limits and a further largish part can be covered by the future exposure (6000 kg day). In case of unobservation of dark matter with such an exposure in the future, the lightest neutralino will remain bino-like and its annihilation is mainly through exchanging the SM-like Higgs boson in order to get the required relic density. (C) 2011 Elsevier B.V. All rights reserved.