scholarly journals Renormalized oscillation theory for Dirac operators

1998 ◽  
Vol 126 (6) ◽  
pp. 1685-1695 ◽  
Author(s):  
Gerald Teschl
1977 ◽  
Vol 123 (12) ◽  
pp. 657 ◽  
Author(s):  
D.E. Vakman ◽  
L.A. Vainshtein
Keyword(s):  

2007 ◽  
Vol 40 (6) ◽  
pp. 885-900 ◽  
Author(s):  
J DOLBEAULT ◽  
M ESTEBAN ◽  
J DUOANDIKOETXEA ◽  
L VEGA
Keyword(s):  

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Shyam Sundar Santra ◽  
Apurba Ghosh ◽  
Omar Bazighifan ◽  
Khaled Mohamed Khedher ◽  
Taher A. Nofal

AbstractIn this work, we present new necessary and sufficient conditions for the oscillation of a class of second-order neutral delay impulsive differential equations. Our oscillation results complement, simplify and improve recent results on oscillation theory of this type of nonlinear neutral impulsive differential equations that appear in the literature. An example is provided to illustrate the value of the main results.


2021 ◽  
Vol 104 (1) ◽  
Author(s):  
Hwancheol Jeong ◽  
Chulwoo Jung ◽  
Seungyeob Jwa ◽  
Jangho Kim ◽  
Jeehun Kim ◽  
...  

Author(s):  
Piero D’Ancona ◽  
Luca Fanelli ◽  
Nico Michele Schiavone

AbstractWe prove that the eigenvalues of the n-dimensional massive Dirac operator $${\mathscr {D}}_0 + V$$ D 0 + V , $$n\ge 2$$ n ≥ 2 , perturbed by a potential V, possibly non-Hermitian, are contained in the union of two disjoint disks of the complex plane, provided V is sufficiently small with respect to the mixed norms $$L^1_{x_j} L^\infty _{{\widehat{x}}_j}$$ L x j 1 L x ^ j ∞ , for $$j\in \{1,\dots ,n\}$$ j ∈ { 1 , ⋯ , n } . In the massless case, we prove instead that the discrete spectrum is empty under the same smallness assumption on V, and in particular the spectrum coincides with the spectrum of the unperturbed operator: $$\sigma ({\mathscr {D}}_0+V)=\sigma ({\mathscr {D}}_0)={\mathbb {R}}$$ σ ( D 0 + V ) = σ ( D 0 ) = R . The main tools used are an abstract version of the Birman–Schwinger principle, which allows in particular to control embedded eigenvalues, and suitable resolvent estimates for the Schrödinger operator.


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