3,708 research outputs found
Mass of the higgs versus fourth generation masses
The predicted value of the higgs mass is analyzed assuming the
existence of the fourth generation of leptons () and quarks ().
The steep and flat directions are found in the five-dimensional parameter
space: , , , , . The LEPTOP fit of the precision
electroweak data is compatible (in particular) with GeV, GeV, GeV, GeV, and GeV. The quality of fits drastically improves when the data on b- and
c-quark asymmetries and new NuTeV data on deep inelastic scattering are
ignored.Comment: 8 pages, 4 figure
On the numerical closeness of the effective phenomenological electroweak mixing angle and the \MS parameter
It happens that and are equal with 0.1% accuracy, though
they are split by radiative corrections and a natural estimate for their
difference is 1%. This degeneracy occurs only for value close to
170\GeV, so no deep physical reason can be attributed to it. However, another
puzzle of the Standard Model, the degeneracy of s_\Eff^2 and , is not
independent of the previous one since a good physical reason exists for
s_\Eff^2 and degeneracy. We present explicit formulas which relate
these three angles.Comment: 10 pages, latex, 3 figures included; published on MPLA. A few
numerical estimates are improved; journal-ref is adde
New global stability estimates for the Gel'fand-Calderon inverse problem
We prove new global stability estimates for the Gel'fand-Calderon inverse
problem in 3D. For sufficiently regular potentials this result of the present
work is a principal improvement of the result of [G. Alessandrini, Stable
determination of conductivity by boundary measurements, Appl. Anal. 27 (1988),
153-172]
New global stability estimates for monochromatic inverse acoustic scattering
We give new global stability estimates for monochromatic inverse acoustic
scattering. These estimates essentially improve estimates of [P. Hahner, T.
Hohage, SIAM J. Math. Anal., 33(3), 2001, 670-685] and can be considered as a
solution of an open problem formulated in the aforementioned work
Diagrammatic calculation of energy spectrum of quantum impurity in degenerate Bose-Einstein condensate
In this paper we considered a quantum particle moving through delute
Bose-Einstein condensate at zero temperature. In our formulation the impurity
particle interacts with the gas of uncoupled Bogoliubov's excitations. We
constructed the perturbation theory for the Green's function of the impurity
particle with respect to the impurity-condensate interaction employing the
coherent-state path integral approach. The perturbative expansion for the
Green's function is resumed into the expansion for its poles with the help of
the diagrammatic technique developed in this work. The dispersion relation for
the impurity clothed by condensate excitations is obtained and effective mass
is evaluated beyond the Golden rule approximation
Once more on extra quark-lepton generations and precision measurements
Precision measurements of -boson parameters and -boson and -quark
masses put strong constraints on non singlet New Physics. We
demonstrate that one extra generation passes electroweak constraints even when
all new particle masses are well above their direct mass bounds.Comment: Dedicated to L.B. Okun's 80th birthda
Two Phases of Supersymmetric Gluodynamics
We argue that supersymmetric gluodynamics has two phases with equivalent
infrared behavior, one of which is asymptotically free and another one is
superstrongly coupled in the ultraviolet domain.Comment: Plain LaTeX, 6 pages, 2 figures in a uuencoded file Final version
which appeared in Phys. Rev. Let.75;2085-2087,1995 Corrected references and
some Comments with no effect on conclusion
Algebras with Operator and Campbell--Hausdorff Formula
We introduce some new classes of algebras and estabilish in these algebras
Campbell--Hausdorff like formula. We describe the application of these
constructions to the problem of the connectivity of the Feynman graphs
corresponding to the Green functions in Quantum Fields Theory.Comment: 12 page
Theory of Z boson decays
The precision data on Z boson decays from LEP-I and SLC colliders are
compared with the predictions based on the Minimal Standard Theory. The Born
approximation of the theory is based on three most accurately known
observables: G_mu -- the four fermion coupling constant of muon decay, m_Z --
the mass of the Z boson, and alpha(m_Z) -- the value of the running fine
structure constant at the scale of m_Z. The electroweak loop corrections are
expressed, in addition, in terms of the masses of higgs, m_H, of the top and
bottom quarks, m_t and m_b, and of the strong interaction constant
alpha_s(m_Z). The main emphasis of the review is focused on the
one-electroweak-loop approximation. Two electroweak loops have been calculated
in the literature only partly. Possible manifestations of new physics are
briefly discussed.Comment: 80 pages, 16 figures, accepted in Reports on Progress in Physic
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