共查询到20条相似文献,搜索用时 31 毫秒
1.
The deviation δQW of the weak charge from its standard model prediction due to the mixing of the W boson with the charged bilepton Y as well as of the Z boson with the neutral Z′ and the real part of the non-Hermitian neutral bilepton X in the economical 3–3–1 model is established. Additional contributions to the usual δQW expression in the extra U(1) models and the left–right models are obtained. Our calculations are quite different from previous analyzes in this kind of the 3–3–1 models and give the limit on mass of the Z′ boson, the Z–Z′ and W–Y mixing angles with the more appropriate values: MZ′>564 GeV, −0.018<sinφ<0 and |sinθ|<0.043. 相似文献
2.
In addition to the narrow spin-one resonances ρT, ωT and aT occurring in low-scale technicolor, there will be relatively narrow scalars in the mass range 200 to 600–700 GeV. We study the lightest isoscalar state, σT. In several important respects it is like a heavy Higgs boson with a small vev. It may be discoverable with high luminosity at the LHC where it is produced via weak boson fusion and likely has substantial W+W− and Z0Z0 decay modes. 相似文献
3.
We analyze the radiative pion decay π+→e+νeγ within nonlocal chiral quark models that include wave function renormalization. In this framework we calculate the vector and axial-vector form factors FV and FA at q2=0 — where q2 is the e+νe squared invariant mass — and the slope a of FV(q2) at q2→0. The calculations are carried out considering different nonlocal form factors, in particular those taken from lattice QCD evaluations, showing a reasonable agreement with the corresponding experimental data. The comparison of our results with those obtained in the (local) NJL model and the relation of FV and a with the form factor in π0→γ?γ decays are discussed. 相似文献
4.
We employ chaotic (?2 and ?4) inflation to illustrate the important role radiative corrections can play during the inflationary phase. Yukawa interactions of ? , in particular, lead to corrections of the form −κ?4ln(?/μ), where κ>0 and μ is a renormalization scale. For instance, ?4 chaotic inflation with radiative corrections looks compatible with the most recent WMAP (5 year) analysis, in sharp contrast to the tree level case. We obtain the 95% confidence limits 2.4×10−14?κ?5.7×10−14, 0.931?ns?0.958 and 0.038?r?0.205, where ns and r respectively denote the scalar spectral index and scalar to tensor ratio. The limits for ?2 inflation are κ?7.7×10−15, 0.929?ns?0.966 and 0.023?r?0.135. The next round of precision experiments should provide a more stringent test of realistic chaotic ?2 and ?4 inflation. 相似文献
5.
6.
We discuss space-time symmetric Hamiltonian operators of the form H=H0+igH′, where H0 is Hermitian and g real. H0 is invariant under the unitary operations of a point group G while H′ is invariant under transformation by elements of a subgroup G′ of G. If G exhibits irreducible representations of dimension greater than unity, then it is possible that H has complex eigenvalues for sufficiently small nonzero values of g. In the particular case that H is parity-time symmetric then it appears to exhibit real eigenvalues for all 0<g<gc, where gc is the exceptional point closest to the origin. Point-group symmetry and perturbation theory enable one to predict whether H may exhibit real or complex eigenvalues for g>0. We illustrate the main theoretical results and conclusions of this paper by means of two- and three-dimensional Hamiltonians exhibiting a variety of different point-group symmetries. 相似文献
7.
8.
A family of spherically symmetric solutions with horizon in the model with m -component anisotropic fluid is presented. The metrics are defined on a manifold that contains a product of n−1 Ricci-flat “internal” spaces. The equation of state for any s -th component is defined by a vector Us belonging to Rn+1. The solutions are governed by moduli functions Hs obeying non-linear differential equations with certain boundary conditions imposed. A simulation of black brane solutions in the model with antisymmetric forms is considered. An example of solution imitating M2–M5 configuration (in D=11 supergravity) corresponding to Lie algebra A2 is presented. 相似文献
9.
T. Rożek D. Grzonka H.-H. Adam A. Budzanowski R. Czyżykiewicz M. Janusz L. Jarczyk B. Kamys A. Khoukaz K. Kilian P. Klaja P. Kowina P. Moskal W. Oelert C. Piskor-Ignatowicz J. Przerwa J. Ritman T. Sefzick M. Siemaszko J. Smyrski A. Täschner P. Winter M. Wolke P. Wüstner Z. Zhang W. Zipper 《Physics letters. [Part B]》2006
10.
We calculate low scale gravity effects on the cross section for neutrino–nucleon scattering at center of mass energies up to the Greisen–Zatsepin–Kuzmin (GZK) scale, in the eikonal approximation. We compare the cases of an infinitely thin brane embedded in n=5 compactified extra-dimensions, and of a brane with a physical tension MS=1 TeV and MS=10 TeV. The extra dimensional Planck scale MD is set at 103 GeV and 2×103 GeV. We also compare our calculations with neutral current standard model calculations in the same energy range, and compare the thin brane eikonal cross section to its saddle point approximation. New physics effects enhance the cross section by orders of magnitude on average. They are quite sensitive to MS and MD choices, though much less sensitive to n. 相似文献
11.
We discuss three Hamiltonians, each with a central-field part H0 and a PT-symmetric perturbation igz. When H0 is the isotropic Harmonic oscillator the spectrum is real for all g because H is isospectral to H0+g2/2. When H0 is the Hydrogen atom then infinitely many eigenvalues are complex for all g. If the potential in H0 is linear in the radial variable r then the spectrum of H exhibits real eigenvalues for 0<g<gc and a PT phase transition at gc. 相似文献
12.
13.
The charged current neutrino–nucleon interaction differential cross section are evaluated in the kinematical range 30<Eν<300 GeV, 0.1<x<0.8 and 0<y<1 using QCD inspired Thermodynamic Bag Model (TBM). We also discuss the x and Q2 dependence of nucleon structure functions F2(x,Q2) and xF3(x,Q2) estimated with statistical approach. The contribution of strange quark distribution function to the cross section is explored and the results obtained have been compared with relevant data from NuTeV and CHORUS experiments. 相似文献
14.
It is argued that the dominant contribution to the interaction of quark–gluon plasma at moderate T?Tc is given by the nonperturbative vacuum field correlators. Basing on that nonperturbative equation of state of quark–gluon plasma is computed and in the lowest approximation expressed in terms of absolute values of Polyakov lines for quarks and gluons Lfund(T),Ladj(T)=(Lfund)9/4 known from lattice and analytic calculations. Phase transition at any μ is described as a transition due to vanishing of one of correlators, DE(x), which implies the change of gluonic condensate ΔG2. Resulting transition temperature Tc(μ) is calculated in terms of ΔG2 and Lfund(Tc). The phase curve Tc(μ) is in a good agreement with lattice data. In particular Tc(0)=0.27; 0.19; 0.17 GeV for nf=0,2,3 and fixed ΔG2=0.0035 GeV4. 相似文献
15.
A non-Abelian finite flavor group G⊂SO(3) can have double covering G′⊂SU(2) such that G⊄G′. This situation is not contradictory, but quite natural, and we give explicit examples such as G=Dn, G′=Q2n and G=T, G′=T′. This observation can be crucial in particle theory model building. 相似文献
16.
Considering gravitino dark matter scenarios with a long-lived charged slepton, we show that collider measurements of the slepton mass and its lifetime can probe not only the gravitino mass but also the post-inflationary reheating temperature TR. In a model independent way, we derive upper limits on TR and discuss them in light of the constraints from the primordial catalysis of 6Li through bound-state effects. In the collider-friendly region of slepton masses below 1 TeV, the obtained conservative estimate of the maximum reheating temperature is about TR=3×109 GeV for the limiting case of a small gluino–slepton mass splitting and about TR=108 GeV for the case that is typical for universal soft supersymmetry breaking parameters at the scale of grand unification. We find that a determination of the gluino–slepton mass ratio at the Large Hadron Collider will test the possibility of TR>109 GeV and thereby the viability of thermal leptogenesis with hierarchical heavy right-handed Majorana neutrinos. 相似文献
17.
We derive target mass corrections (TMC) for the spin-dependent nucleon structure function g1 and polarization asymmetry A1 in collinear factorization at leading twist. The TMCs are found to be significant for g1 at large xB, even at relatively high Q2 values, but largely cancel in A1. A comparison of TMCs obtained from collinear factorization and from the operator product expansion shows that at low Q2 the corrections drive the proton A1 in opposite directions. 相似文献
18.
19.
We show that the newly measured branching ratios of vector charmonia (J/ψ, ψ′ and ψ(3770)) into γP, where P stands for light pseudoscalar mesons π0, η , and η′, can be well understood in the framework of vector meson dominance (VMD) in association with the ηc–η(η′) mixings due to the axial gluonic anomaly. These two mechanisms behave differently in J/ψ and ψ′→γP. A coherent understanding of the branching ratio patterns observed in J/ψ(ψ′)→γP can be achieved by self-consistently including those transition mechanisms at hadronic level. The branching ratios for ψ(3770)→γP are predicted to be rather small. 相似文献
20.
R.M. Clark K.E. Gregorich J.S. Berryman M.N. Ali J.M. Allmond C.W. Beausang M. Cromaz M.A. Deleplanque I. Dragojevi? J. Dvorak P.A. Ellison P. Fallon M.A. Garcia J.M. Gates S. Gros H.B. Jeppesen D. Kaji I.Y. Lee A.O. Macchiavelli K. Morimoto H. Nitsche S. Paschalis M. Petri L. Stavsetra F.S. Stephens H. Watanabe M. Wiedeking 《Physics letters. [Part B]》2010
We report results from an experiment on the decay of the high-K isomers in 254No. We have been able to establish the decay from the known high-lying four-quasiparticle isomer, which we assign as a Kπ=16+ state at an excitation energy of Ex=2.928(3) MeV. The decay of this state passes through a rotational band based on a previously unobserved state at Ex=2.012(2) MeV, which we suggest is based on a two-quasineutron configuration with Kπ=10+. This state in turn decays to a rotational band based on the known Kπ=8− isomer, which we infer must also have a two quasineutron configuration. We are able to assign many new gamma-rays associated with the decay of the Kπ=8− isomer, including the identification of a highly K-forbidden ΔK=8 E1 transition to the ground-state band. These results provide valuable new information on the orbitals close to the Fermi surface, pairing correlations, deformation and rotational response, and K-conservation in nuclei of the deformed trans-fermium region. 相似文献