63 research outputs found
Full O(alpha) corrections to e+e- -> sf_i sf_j
We present a complete precision analysis of the sfermion pair production
process e+e- -> sf_i sf_j (f = t, b, tau, nu_tau) in the Minimal Supersymmetric
Standard Model. Our results extend the previously calculated weak corrections
by including all one-loop corrections together with higher order QED
corrections. We present the details of the analytical calculation and discuss
the renormalization scheme. The numerical analysis shows the results for total
cross-sections, forward-backward and left-right asymmetries. It is based on the
SPS1a' point from the SPA project. The complete corrections are about 10% and
have to be taken into account in a high precision analysis.Comment: 32 pages, 24 figures, RevTeX
Two dimensional Berezin-Li-Yau inequalities with a correction term
We improve the Berezin-Li-Yau inequality in dimension two by adding a
positive correction term to its right-hand side. It is also shown that the
asymptotical behaviour of the correction term is almost optimal. This improves
a previous result by Melas.Comment: 6 figure
On the lowest eigenvalue of Laplace operators with mixed boundary conditions
In this paper we consider a Robin-type Laplace operator on bounded domains.
We study the dependence of its lowest eigenvalue on the boundary conditions and
its asymptotic behavior in shrinking and expanding domains. For convex domains
we establish two-sided estimates on the lowest eigenvalues in terms of the
inradius and of the boundary conditions
Scorpions of Iran (Arachnida: Scorpiones). Part VI. Lorestan Province
Ten species of scorpions belonging to three families are reported from the Lorestan Province of Iran. Of these, five species are recorded from the province for the first time: Hottentotta zagrosensis KovaĹ™Ăk, 1997; Mesobuthus eupeus phillipsii (Pocock, 1889); Orthochirus iranus KovaĹ™Ăk, 2004; Razianus zarudnyi (Birula, 1903); and Scorpio maurus townsendi (Pocock, 1900). One new species is described, Hottentotta lorestanus sp. n.; it can be easily distinguished from the other four species of the genus known from Iran by its coloration; it is the only Iranian species which has the entire pedipalps yellow and the metasomal segments I to IV greenish gray. Also presented is a key to all species of scorpions found in the province
Scorpions of Iran (Arachnida: Scorpiones). Part VI. Lorestan Province
Ten species of scorpions belonging to three families are reported from the Lorestan Province of Iran. Of these, five species are recorded from the province for the first time: Hottentotta zagrosensis KovaĹ™Ăk, 1997; Mesobuthus eupeus phillipsii (Pocock, 1889); Orthochirus iranus KovaĹ™Ăk, 2004; Razianus zarudnyi (Birula, 1903) ; and Scorpio maurus townsendi (Pocock, 1900). One new species is described, Hottentotta lorestanus sp. n.; it can be easily distinguished from the other four species of the genus known from Iran by its coloration; it is the only Iranian species which has the entire pedipalps yellow and the metasomal segments I to IV greenish gray. Also presented is a key to all species of scorpions found in the province
Spectrum of the Schr\"odinger operator in a perturbed periodically twisted tube
We study Dirichlet Laplacian in a screw-shaped region, i.e. a straight
twisted tube of a non-circular cross section. It is shown that a local
perturbation which consists of "slowing down" the twisting in the mean gives
rise to a non-empty discrete spectrum.Comment: LaTeX2e, 10 page
A Hardy inequality in twisted waveguides
We show that twisting of an infinite straight three-dimensional tube with
non-circular cross-section gives rise to a Hardy-type inequality for the
associated Dirichlet Laplacian. As an application we prove certain stability of
the spectrum of the Dirichlet Laplacian in locally and mildly bent tubes.
Namely, it is known that any local bending, no matter how small, generates
eigenvalues below the essential spectrum of the Laplacian in the tubes with
arbitrary cross-sections rotated along a reference curve in an appropriate way.
In the present paper we show that for any other rotation some critical strength
of the bending is needed in order to induce a non-empty discrete spectrum.Comment: LaTeX, 20 page
A simple proof of Hardy-Lieb-Thirring inequalities
We give a short and unified proof of Hardy-Lieb-Thirring inequalities for
moments of eigenvalues of fractional Schroedinger operators. The proof covers
the optimal parameter range. It is based on a recent inequality by Solovej,
Soerensen, and Spitzer. Moreover, we prove that any non-magnetic Lieb-Thirring
inequality implies a magnetic Lieb-Thirring inequality (with possibly a larger
constant).Comment: 12 page
Weakly coupled bound states of Pauli operators
We consider the two-dimensional Pauli operator perturbed by a weakly coupled,
attractive potential. We show that besides the eigenvalues arising from the
Aharonov-Casher zero modes there are two or one (depending on whether the flux
of the magnetic field is integer or not) additional eigenvalues for arbitrarily
small coupling and we calculate their asymptotics in the weak coupling limit.Comment: 19 page
Resonances in Models of Spin Dependent Point Interactions
In dimension we define a family of two-channel Hamiltonians
obtained as point perturbations of the generator of the free decoupled
dynamics. Within the family we choose two Hamiltonians, and \hat
H_\ve, giving rise respectively to the unperturbed and to the perturbed
evolution. The Hamiltonian does not couple the channels and has an
eigenvalue embedded in the continuous spectrum. The Hamiltonian \hat H_\ve is
a small perturbation, in resolvent sense, of and exhibits a small
coupling between the channels.
We take advantage of the complete solvability of our model to prove with
simple arguments that the embedded eigenvalue of shifts into a
resonance for \hat H_\ve. In dimension three we analyze details of the time
behavior of the projection onto the region of the spectrum close to the
resonance.Comment: Changes in the proof of theorem 3, few misprints corrected, 21 page
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