Qweak, N → Δ, and physics beyond the standard model

The data-taking phase of the Qweak experiment ended in May of 2012 at the Thomas Jefferson National Accelerator Facility. Qweak aims to measure the weak charge of the proton, Q _W ^p , via parity-violating elastic electron-proton scattering. The expected value of Q _W ^p is fortuitously suppressed, which leads to an increased sensitivity to physics beyond the Standard Model.     

MAP,MAC, and vortex-rings configurations in the Weinberg–Salam model

We report on the presence of new axially symmetric monopoles, antimonopoles and vortex-rings solutions of the SU(2)×U(1) Weinberg–Salam model of electromagnetic and weak interactions. When the ?$?$-winding number n=1$n=1$, and 2, the configurations are monopole–antimonopole pair (MAP) and monopole–antimonopole chain (MAC) with poles of alternating sign magnetic charge arranged along the z$z$-axis. Vortex-rings start to appear from the MAP and MAC configurations when the winding number n=3$n=3$. The MAP configurations possess zero net magnetic charge whereas the MAC configurations possess net magnetic charge of 4πn/e$4\pi n/e$.     

Radial excitations of scalar, η, and η′ mesons in a chiral quark model

First radial excitations of the scalar-meson nonet and of the pseudoscalar mesons η and η′ are described within a nonlocal chiral quark model of the Nambu-Jona-Lasinio type with ′t Hooft interaction. In this model, simple form factors are used, which allows us to describe first radial excitations of the mesons and to retain the gap equations describing spontaneous breakdown of chiral symmetry in the standard form. The external parameters of form factors are fixed by the masses of excited pseudoscalar mesons, and the same form factors are used to predict the masses of excited scalar mesons. The strong decays of excited scalar mesons and of η and η′ mesons are described in satisfactory agreement with experimental data.     

Bs,d → μ+μ- decays in a flavor changing Z' model decays in a flavor changing Z' model

We study the pure leptonic decays Bs,d→μ+μ- in a Flavor Changing Z' Model. Prom the recent measurements of the branching ratios β(Bs,d →μ+μ-).we have derived the bounds on the effective μ-μ-Z' lepton coupling BμμL. We find that, (i) if neglecting the contribution from the right-handed lepton coupling BμμR, we obtain 1.32 < BμμL < 3.32; (ii) if considering the contribution from the right-handed lepton coupling BμμR and setting BμμL = BμμR, we obtain 0.99 < BμμL < 2.19. Our results could be useful for researching Z' effects.     

Instantaneous information propagation in free flow, synchronized flow, stop-and-go waves in a cellular automaton model

Recently, a number of efforts are underway to investigate inter-vehicle communications （IVC）. This paper studies the instantaneous information propagation behaviours based on IVC in three different tragic situations （free flow, synchronized flow and stop-and-go waves） in a cellular automaton model. It is shown that different behaviours appear in stop-and-go waves from those in free flow and synchronized flow. While the distribution of Multi-hop Communication Distance （MhCD） is either exponential or uniform in free flow and synchronized flow, the distribution of MhCD is either exponential or with a single peak in stop-and-go waves.     

Shell model structure at100Sn — The nuclides98Ag,103In,and104, 105Sn

The neutron deficient nuclei⁹⁸Ag,¹⁰⁴Sn withT _z =2 and¹⁰³In,¹⁰⁵Sn (T _z=5/2) were studied in-beam following the reaction of 250 MeV⁵⁸Ni+⁵⁰Cr. Neutron and charged particle (p, ) gated-coincidence spectra were used to identify these nuclei, which are populated with yields between 0.05% and 2% of the total residue cross section, and to determine their level schemes. In a comprehensive shell model study various approaches for the residual interaction were used to describe these newly and several previously studied neutron deficient nuclei. As a result predictions for the neutron single particle energies for¹⁰⁰Sn are obtained and used to discuss the next generation of experiments.The authors gratefully acknowledge the assistance of L. Käubler and H. Rotter in the experiment, of R. Jerecic in the centroid shift analysis, and fruitful discussions with D. B. Fossan, D. Seweryniak and our collegues from the NORDBALL collaboration.     

Soliton management in the nonlinear Schrödinger equation model with varying dispersion, nonlinearity, and gain

The novel stable “soliton islands” in a “sea of solitary waves” of the nonlinear Schrödinger equation model with varying dispersion, nonlinearity, and gain or absorption are discovered. Different soliton management regimes are predicted.     

Inclusive ϕ meson production,the parton fusion model and strange quark structure functions

The parton fusion model is used to describe the longitudinal differential cross section (dσ/dx _F ) of hadronic ? production. Thedσ/dx _F for ? production in π^± p, \(\mathop p\limits^{( - )} p\) andK ^± p interactions is evaluated in the model by using structure functions for the constituents of the interacting particles. A comparison between the model and high statistics data in the Feynmanx range 0.0<x _F (?)<0.4 allows the determination of the strange valence quark distribution inK mesons and the strange sea quark distribution in π mesons, which appears to be harder than the light sea quark distribution. The comparison also shows that a significant part of inclusive ? production is due to the OZI allowed fusion of strange quarks, while the OZI inhibited fusion diagrams are strongly suppressed.     

Chiral Thirring–Wess model

The vector type of interaction of the Thirring–Wess model was replaced by the chiral type and a new model was presented which was termed as chiral Thirring–Wess model in Rahaman (2015). The model was studied there with a Faddeevian class of regularization. Few ambiguity parameters were allowed there with the apprehension that unitarity might be threatened like the chiral generation of the Schwinger model. In the present work it has been shown that no counter term containing the regularization ambiguity is needed for this model to be physically sensible. So the chiral Thirring–Wess model is studied here without the presence of any ambiguity parameter and it has been found that the model not only remains exactly solvable but also does not lose the unitarity like the chiral generation of the Schwinger model. The phase space structure and the theoretical spectrum of this new model have been determined in the present scenario. The theoretical spectrum is found to contain a massive boson with ambiguity free mass and a massless boson.     

Competition, efficiency and collective behavior in the “El Farol” bar model

The El Farol bar model, proposed to study the dynamics of competition of agents in a variety of contexts (W.B. Arthur, Amer. Econ. Assoc. Pap. Proc. 84, 406 (1994)) is studied. We characterize in detail the three regions of the phase diagram (efficient, better than random and inefficient) of the simplest version of the model (D. Challet, Y.-C. Zhang, Physica A 246, 407 (1997)). The efficient region is shown to have a rich structure, which is investigated in some detail. Changes in the payoff function enhance further the tendency of the model towards a wasteful distribution of resources. Received 13 November 1998     

Simulation model of speed–density characteristics for mixed bicycle flow—Comparison between cellular automata model and gas dynamics model

The mixed bicycle flow refers to the bicycle flow containing electric bicycles. The traffic characteristics data of the mixed bicycle flow was collected by the virtual coil method in Nanjing and Ningbo, China. And the speed–density characteristics of the mixed bicycle flow with different proportions of electric bicycles were obtained. The results show that the overall speed of the mixed bicycle flow containing electric bicycles is higher than that of pure bicycle flow when the density is relatively low. The speed decreases when the density is higher than 0.08 bic/m²; the speed–density characteristics of the bicycles and the electric bicycles tend to be the same when the density is higher than 0.25 bic/m². And when the density reaches 0.58 bic/m², the mixed bicycle flow becomes blocked and the speed is zero. The cellular automata model and gas dynamics model were also adopted to simulate the speed–density characteristics of the mixed bicycle flow. The simulation results of the cellular automata model are effectively consistent with the actual survey data when the density is lower than 0.225 bic/m²; the simulation results of the gas dynamics model are effectively consistent with the actual survey data when the density is higher than 0.300 bic/m²; but both of the two types of simulation models are inapplicable when the density is between 0.225 and 0.300 bic/m². These results will be used in the management of mixed bicycles and the research of vehicle–bicycle conflict and so on.     

The continuous-spin Ising model,g0∶φ4∶d field theory,and the renormalization group

We have used the method of high-temperature series expansions to investigate the critical point properties of a continuous-spin Ising model and g₀⁴_d Euclidean field theory. We have computed through tenth order the hightemperature series expansions for the magnetization, susceptibility, second derivative of the susceptibility, and the second moment of the spin-spin correlation function on eight different lattices. Our analysis of these series is made using integral and Padé approximants. In three dimensions we find that hyperscaling fails for sufficiently Ising-like systems; the strong coupling limit of g₀⁴₃ depends on how the ultraviolet cutoff is removed. The level contours of the renormalized coupling constant for this model in theg ₀, correlation-length plane exhibit a saddle point. If the ultraviolet cutoff is removed beforeg ₀ , the usual field theory results and the renormalization-group fixed point with hyperscaling is obtained. If the order of these limits is reversed, the Ising model limit where hyperscaling fails and the field theory is trivial is obtained. In four dimensions, we find that hyperscaling fails completely; g₀⁴₄ is trivial for all g₀ when the ultraviolet cutoff is removed.Work supported in part by the U.S. Department of Energy.     

The Weiss model and the Landau–Khalatnikov model for the switching of ferroelectrics

It is shown that the molecular field theory by P. Weiss formally leads to the switching kinetics of ferroelectrics, which is described by the well-known Landau–Khalatnikov equation. The switching has a critical character, taking place only at E_a>E_c (E_a: external field, E_c: coercive field). The results are checked by computer simulations.     

The Sine-Gordon field theory model at α2=8π, the non-superrenormalizable theory

We study the Sine-Gordon field theory at ²=8. We prove that the theory is renormalizable but not superrenormalizable and we show how the perturbative renormalization procedure works in this case where the interaction is not polynomial. To go beyond the perturbative results we investigate the -functional equation for this theory and discuss in what sense at ²=8 the theory is lacking the asymptotic freedom and how it is asymptotic free for ²<8 in a appropriate region of the coupling constants.     

Chinese speaker-recognition based on ARMA model

lIntroductiollSpeakerrecognitioncanbewidelyusedinpublicsecurity,insurance,secrecy,bankingetc.Manyscholarshavespendseveraldecadesstudyingthissubject,andhavegottenmanyachievements,buttherearesomedisadvantagesintheirmethods.Forexample,thegeneralinformation,includingthechargeofvocaltractwhendifferentcontentspeechisspoken,heavilyblursanddestroysindividualinformation,sotheperformanceofrecognitionisnotgood.Insomemethods,thelong-timespeechmaterialisusedtogatherindividualcharacteristicsandthecomplextra…     

Non-Hermitian Ising model at finite temperature

As a very simple model, the Ising model plays an important role in statistical physics. In the paper,with the help of quantum Liouvillian statistical theory, we study the one-dimensional nonHermitian Ising model at finite temperature and give its analytical solutions. We find that the nonHermitian Ising model shows quite different properties from those of its Hermitian counterpart. For example, the ‘pseudo-phase transition’ is explored between the ‘topological’ phase and the ‘nontopological’ pha...