共查询到20条相似文献,搜索用时 11 毫秒
1.
I. M. Narodetskii 《Physics of Atomic Nuclei》2003,66(11):1972-1988
The paper represents a review of our present knowledge on the phenomenology of weak decays of quarks and their role in the determination of the parameters of the Standard Model. Specifically, we focus on CP violation in B decays and the determination of the Cabibbo-Kobayashi-Maskawa matrix element Vcb from exclusive and inclusive semileptonic B decays. We also briefly discuss phenomeno-logical applications concerning the electron energy spectra in inclusive semileptonic B and Bc decays. 相似文献
2.
We review CP-violating effects in
jet and
4 jet decays, assuming the presence of CP-violating effective
and
couplings. Longitudinal beam polarization is included in the studies. We propose a direct search for such CP-violating couplings by using various CP-odd observables. The data of a future linear collider running at the Z-resonance in the so-called GigaZ option should give significant information on the couplings. Finally we show that stringent bounds on the mass of excited b quarks can be derived if appropriate couplings are of a size characteristic of a strong interaction.Received: 21 August 2003, Published online: 20 November 2003 相似文献
3.
V. A. Koval’chuk 《Journal of Experimental and Theoretical Physics》2008,107(5):774-786
Effects of CP and T invariance violation are studied in the most general interaction of the Higgs boson with the intermediate vector W ± and Z bosons. Various angular distributions of the cascade decay Φ → W + W ?/ZZ → 4 of fermions in the transversity and helicity systems are calculated, and asymmetries are constructed and evaluated. It is shown that studying the azimuthal angle distribution of the process Φ → ZZ → (e ? e +)(μ?μ+) in the transversity system is effective for measuring the spatial parity of the Higgs boson. 相似文献
4.
An effective two-doublet Higgs potential that involves complex-valued parameters and whose CP invariance is violated both explicitly and spontaneously is considered. The problem of diagonalizing the mass term of this potential at a local minimum is solved. The eigenstates of Higgs bosons and their mass spectrum are obtained for the special case of the two-doublet Higgs sector of the minimal supersymmetric model, where the CP invariance of the effective potential is violated owing to the interactions of the Higgs fields with the third-generation scalar quarks. 相似文献
5.
If the present or upcoming searches for neutrinoless double beta ((ββ)0ν) decay give a positive result, the Majorana nature of massive neutrinos will be established. From the determination of the value of the (ββ)0ν-decay effective Majorana mass parameter (|〈m〉|), it would be possible to obtain information on the type of neutrino mass spectrum. Assuming 3-ν mixing and massive Majorana neutrinos, we discuss the information that a measurement of, or an upper bound on, |〈m〉| can provide on the value of the lightest neutrino mass m1. With additional data on the neutrino masses obtained in 3H β-decay experiments, it might be possible to establish whether the CP symmetry is violated in the lepton sector. This would require very high precision measurements. If CP invariance holds, the allowed patterns of the relative CP parities of the massive Majorana neutrinos would be determined. 相似文献
6.
7.
For large masses, the two heavy neutral Higgs bosons are nearly degenerate in many 2-Higgs doublet models, and particularly in supersymmetric models. In such a scenario the mixing between the states can be very large if the theory is CP-noninvariant. We analyze the formalism describing this configuration, and we point to some interesting experimental consequences.Received: 1 October 2004, Revised: 10 January 2005, Published online: 9 March 2005 相似文献
8.
An exponential form of the Pontecorvo–Maki–Nakagawa–Sakatamixingmatrix for neutrinos is discussed. This form makes it possible to separate the contributions of purely rotational components of the mixing matrix and elements that are responsible for CP violation. The logarithm of the mixing matrix and exact values for each parameter of the exponential neutrino mixing matrix are found on the basis of the most recent experimental data on neutrino mixing. The parameters of the real rotational part in the exponential representation of the mixing matrix and the parameters of its imaginary part, which is responsible for CP violation, are evaluated. The hypothesis of complementarity of quark and neutrino mixing is confirmed. Factorization in the form of the product of rotations about the real and imaginary axes is demonstrated. 相似文献
9.
E. N. Akhmetzyanova M. V. Dolgopolov M. N. Dubinin I. A. Smirnov 《Physics of Atomic Nuclei》2005,68(3):541-548
The most general form of an effective two-doublet Higgs potential whose parameters are complex-valued and whose CP invariance is violated explicitly in the minimal supersymmetric model caused by Higgs boson interaction with third-generation squarks is considered. Higgs boson states are obtained and their masses are calculated, along with the decay widths of the lightest Higgs boson and the cross section for its production, in the case of substantial mixing between the CP-even states h and H and the CP-odd state A. 相似文献
10.
J. Gasser B. Kubis N. Paver M. Verbeni 《The European Physical Journal C - Particles and Fields》2005,40(2):205-227
Motivated by recent experimental results and ongoing measurements, we review the chiral perturbation theory prediction for
decays. Special emphasis is given to the stability of the inner bremsstrahlung-dominated relative branching ratio versus the K
e3 form factors, and on the separation of the structure-dependent amplitude in differential distributions over the phase space. For the structure-dependent terms, an assessment of the order p
6 corrections is given, in particular, a full next-to-leading order calculation of the axial component is performed. The experimental analysis of the photon energy spectrum is discussed, and other potentially useful distributions are introduced.Received: 9 December 2004, Published online: 21 February 2005PACS:
13.20.Eb, 11.30.Rd, 12.39.Fe 相似文献
11.
From a macroscopic theory of the quantum vacuum in terms of conserved relativistic charges (generically denoted by q
(a) with label a), we have obtained, in the low-energy limit, a particular type of f(R) model relevant to cosmology. The macroscopic quantum-vacuum theory allows us to distinguish between different phenomenological
f(R) models on physical grounds.
The text was submitted by the authors in English. 相似文献
12.
V. Cirigliano H. Neufeld H. Pichl 《The European Physical Journal C - Particles and Fields》2004,35(1):53-65
We present a detailed numerical study of the Ke3 decays to
in chiral perturbation theory with virtual photons and leptons. We describe the extraction of the CKM matrix element |Vus| from the experimental Ke3 decay parameters. We propose a consistency check of the K + e3 and K0e3 data that is largely insensitive to the dominating theoretical uncertainties, in particular the contributions of
. Our analysis is highly relevant in view of the recent high statistics measurement of the K + e3 branching ratio by E865 at Brookhaven which does not indicate any significant deviation from CKM unitarity but rather a discrepancy with the present K0e3 data.Received: 22 January 2004, Published online: 30 April 2004Work supported in part by IHP-RTN, Contract No. HPRN-CT2002-00311 (EURIDICE) and by Acciones Integradas, Project No. 19/2003 (Austria), HU2002-0044 (MCYT, Spain) 相似文献
13.
14.
In a recent paper (Sharif and Shamir in Class. Quantum Grav. 26:235020, 2009), we have studied the vacuum solutions of Bianchi
types I and V spacetimes in the framework of metric f (R) gravity. Here we extend this work to perfect fluid solutions. For this purpose, we take stiff matter to find energy density
and pressure of the universe. In particular, we find two exact solutions in each case which correspond to two models of the
universe. The first solution gives a singular model while the second solution provides a non-singular model. The physical
behavior of these models has been discussed using some physical quantities. Also, the function of the Ricci scalar is evaluated. 相似文献
15.
S. R. Gevorkyan A. N. Sissakian A. V. Tarasov H. T. Torosyan O. O. Voskresenskaya 《Physics of Atomic Nuclei》2010,73(6):961-964
The final-state interaction of pions in K
e4 decay allows to obtain the value of the isospin and angular-momentum-zero ππ scattering length a
00.We take into account the electromagnetic interaction of pions and isospin-symmetry-breaking effects caused by different masses
of neutral and charged pions and estimate the impact of these effects on the procedure of scattering-length extraction from
K
e4 decays. 相似文献
16.
17.
Analytical expressions are obtained for the angular distributions and spin asymmetries of the processes of elastic electromagnetic
and electroweak scattering of high energy electrons on polarized/unpolarized proton target with account of C-, P- and T/CP-invariance violating anapole and electric dipole moments, as well as neutral weak electric, magnetic and axial form factors
of the proton. Behavior of the P- and T- odd spin asymmetries is studied in dependence of the electron’s energy and scattering angle and proton form factors parameters. 相似文献
18.
A. E. Dorokhov 《Czechoslovak Journal of Physics》2001,51(1):A145-A151
We review some aspects of rare kaon decays with the polarization of outgoing muons that allows one to study a number of interesting CP-odd or T-odd observables. 相似文献
19.
Teng Wang Tianbo Liu Da-Xin Zhang Bo-Qiang Ma 《The European Physical Journal C - Particles and Fields》2011,71(9):1758
We investigate the rare decays \(B_{c} \rightarrow D_{s}(1968)\ell \overline{\ell}\) and \(B_{c}\rightarrow D_{s}^{*}(2317) \ell \overline{\ell}\) in the framework of the light-cone quark model (LCQM). The transition form factors are calculated in the space-like region and then analytically continued to the time-like region via exponential parametrization. The branching ratios and longitudinal lepton polarization asymmetries (LPAs) for the two decays are given and compared with each other. The results are helpful for investigating the structure of B c meson and for testing the unitarity of CKM quark mixing matrix. All these results can be tested in the future experiments at the LHC. 相似文献
20.
Mostefa Djermouni Ali Zaoui Salima Kacimi Nawel Benayad Abdelkader Boukortt 《The European Physical Journal B - Condensed Matter and Complex Systems》2018,91(2):28
Ferromagnetism and ferroelectricity in Eu monochalcogenides have been investigated by ab initio density functional theory in the DFT+U approach. Exchange interaction parameters and Curie temperatures under pressure are studied and discussed using Heisenberg Hamiltonian with first and second-nearest-neighbor interactions. The calculations showed that the hydrostatic pressure perfectly improves the Curie temperature (EuO: T C = 175 K; EuS: T C = 33.8 K) and in the other hand it cannot induce the spontaneous polarization (P s ). The effect of uniaxial and biaxial pressure is also studied. Although the uniaxial strains slightly increases the Curie temperature, it ensures the ferrolectricity in these systems by producing a spontaneous polarization of the order of P s (EuO) = 57.50 μC/cm2 and P s (EuS) = 42.86 μC/cm2 with pressures of 5% and 4%, respectively. The search for new model systems is a necessity to better understand the physics related to multiferroïc materials and to consider possible applications. 相似文献