Initial-state nuclear effects in proton-nucleus collisions

Two important initial-state nuclear effects in hadron-nucleus collisions are considered. The ratios of inclusive differential cross sections for Drell-Yan dimuon production are calculated. The calculated results are compared to the E866 data. It is shown that consideration of multiple soft rescatterings of incident quarks in nuclei and initial-state quark energy loss effects allow to get a good agreement between the calculated results and the experimental data.Comment: 6 pages, 6 figure

Correlator of Topological Charge Densities in Instanton Model in QCD

The QCD sum rule for the correlator of topological charge densities and related to it longitudinal part of the correlator of singlet axial currents is considered in the framework of instanton model. The coupling constant of eta'-meson with the singlet axial current is determined. Its value appears to be in a good coincidence with the value determined recently from the connection of the part of proton spin, carried by u,d,s quarks, with the derivative of QCD topological susceptibility. From the same sum rule eta-eta' mixing angle is found in the framework of two mixing angles model. Its value is close to that found in the chiral effective theory. The correlator of topological charge densities at large momenta is calculated.Comment: 14 pages, 2 figure

On factorization of q-difference equation for continuous q-Hermite polynomials

We argue that a customary q-difference equation for the continuous q-Hermite polynomials H_n(x|q) can be written in the factorized form as (D_q^2 - 1)H_n(x|q)=(q^{-n}-1)H_n(x|q), where D_q is some explicitly known q-difference operator. This means that the polynomials H_n(x|q) are in fact governed by the q-difference equation D_qH_n(x|q)=q^{-n/2}H_n(x|q), which is simpler than the conventional one.Comment: 7 page

Coherent Schwinger Interaction from Darboux Transformation

The exactly solvable scalar-tensor potential of the four-component Dirac equation has been obtained by the Darboux transformation method. The constructed potential has been interpreted in terms of nucleon-nucleon and Schwinger interactions of neutral particles with lattice sites during their channeling Hamiltonians of a Schwinger type is obtained by means of the Darboux transformation chain. The analitic structure of the Lyapunov function of periodic continuation for each of the Hamiltonians of the family is considered.Comment: 12 pages, Latex, six figures; six sections, one figure adde

PT symmetry, Cartan decompositions, Lie triple systems and Krein space related Clifford algebras

Gauged PT quantum mechanics (PTQM) and corresponding Krein space setups are studied. For models with constant non-Abelian gauge potentials and extended parity inversions compact and noncompact Lie group components are analyzed via Cartan decompositions. A Lie triple structure is found and an interpretation as PT-symmetrically generalized Jaynes-Cummings model is possible with close relation to recently studied cavity QED setups with transmon states in multilevel artificial atoms. For models with Abelian gauge potentials a hidden Clifford algebra structure is found and used to obtain the fundamental symmetry of Krein space related J-selfadjoint extensions for PTQM setups with ultra-localized potentials.Comment: 11 page

Gauge theory in deformed N=(1,1) superspace

We review the non-anticommutative Q-deformations of N=(1,1) supersymmetric theories in four-dimensional Euclidean harmonic superspace. These deformations preserve chirality and harmonic Grassmann analyticity. The associated field theories arise as a low-energy limit of string theory in specific backgrounds and generalize the Moyal-deformed supersymmetric field theories. A characteristic feature of the Q-deformed theories is the half-breaking of supersymmetry in the chiral sector of the Euclidean superspace. Our main focus is on the chiral singlet Q-deformation, which is distinguished by preserving the SO(4) Spin(4) ``Lorentz'' symmetry and the SU(2) R-symmetry. We present the superfield and component structures of the deformed N=(1,0) supersymmetric gauge theory as well as of hypermultiplets coupled to a gauge superfield: invariant actions, deformed transformation rules, and so on. We discuss quantum aspects of these models and prove their renormalizability in the abelian case. For the charged hypermultiplet in an abelian gauge superfield background we construct the deformed holomorphic effective action.Comment: 1+60 pages, typos corrected, references adde

Projective Hilbert space structures at exceptional points

A non-Hermitian complex symmetric 2x2 matrix toy model is used to study projective Hilbert space structures in the vicinity of exceptional points (EPs). The bi-orthogonal eigenvectors of a diagonalizable matrix are Puiseux-expanded in terms of the root vectors at the EP. It is shown that the apparent contradiction between the two incompatible normalization conditions with finite and singular behavior in the EP-limit can be resolved by projectively extending the original Hilbert space. The complementary normalization conditions correspond then to two different affine charts of this enlarged projective Hilbert space. Geometric phase and phase jump behavior are analyzed and the usefulness of the phase rigidity as measure for the distance to EP configurations is demonstrated. Finally, EP-related aspects of PT-symmetrically extended Quantum Mechanics are discussed and a conjecture concerning the quantum brachistochrone problem is formulated.Comment: 20 pages; discussion extended, refs added; bug correcte

Dpes massless QCD have vacuum energy?

It is widely thought that this question has a positive answer, but we argue that the support for this belief from both experiment and theory is weak or nonexistent. We then list some of the ramifications of a negative answer.Comment: 8 pages, no figures, version to appear in NJ

Efficacy and safety of the use of rebamipide in the scheme of triple eradication therapy of Helicobacter pylori infection: a prospective randomized comparative study

Purpose of the study. To evaluate the effectiveness and safety of the use of rebamipide as part of the triple eradication therapy (ET) scheme of Helicobacter pylori infection. Materials and methods. A prospective, randomized comparative study included 94 patients with uncomplicated H. pylori-associated stomach / duodenal ulcer. In the process of randomization, patients are divided into three groups depending on the intended therapy. The first group (n=36) received a classical triple scheme of the first-line ET (omeprazole 20 mg twice a day, amoxicillin 1000 mg twice a day, clarithromycin 500 mg twice a day) for 10 days. Patients of the second group (n=33) were assigned a classical triple scheme of ET with the inclusion of rebamipide (omeprazole 20 mg twice a day, amoxicillin 1000 mg twice a day, clarithromycin 500 mg twice a day, rebamipide 100 mg 3 times a day day) for 10 days. Patients of the third group (n=25) were assigned a classical triple scheme of ET with the inclusion of rebamipide (omeprazole 20 mg twice a day, amoxicillin 1000 mg twice a day, clarithromycin 500 mg twice a day, rebamipide 100 mg 3 times a day) in for 10 days, with the prolongation of the administration of rebamipide for the next 20 days. The effectiveness of ET was determined by the respiratory test after 6 weeks after the end of treatment. Adverse events were recorded by patients in specially developed diaries. All patients with gastric ulcer at the 6th week underwent a histological examination of the biopsy specimens of the antrum and the body of the stomach, assessing the inflammatory activity of the process on a point system in accordance with the updated Sydney system. Results and discussion. Efficiency of H. pylori eradication in the first group was 77.7% (ITT), 82.3% (PP), in the second group - 81.8% (ITT), 84.4% (PP), and in the third group - 84% (ITT), 87.5% (PP). The use of rebamipide in the triple ET regimen was associated with an increase in H. pylori eradication efficiency, both with simultaneous use with the scheme [odds ratio (OR) 1.16; 95% confidence interval (CI) 0.32-4.24], and with subsequent prolonged admission (OR 1.5, 95% CI 0.34-6.7). A somewhat more pronounced dynamics of the epithelization of erosive and ulcerative changes in the mucous membrane of the stomach and duodenum to the 21st and 28th days in the third group of patients was noted. The incidence of adverse events between the groups was comparable: 22.2% in the first group, 24.2% in the second group and 20% in the third group. In the pathomorphological evaluation of biopsy specimens of patients with gastric ulcer at the 6th week after the treatment, significant differences were revealed between the first and third groups in terms of the inflammatory activity in the antrum stomach (2±0.63 vs. 1.4±0.52; p=0,0399). The conclusion. The inclusion of rebamipide in the classical triple scheme of H. pylori ET increases the effectiveness of treatment and does not affect the safety profile. In the post-eradication period, it is advisable to continue the use of rebamipide to potentiate the repair of the gastric mucosa and regress the inflammatory processes

Nonlocal supersymmetric deformations of periodic potentials

Irreducible second-order Darboux transformations are applied to the periodic Schrodinger's operators. It is shown that for the pairs of factorization energies inside of the same forbidden band they can create new non-singular potentials with periodicity defects and bound states embedded into the spectral gaps. The method is applied to the Lame and periodic piece-wise transparent potentials. An interesting phenomenon of translational Darboux invariance reveals nonlocal aspects of the supersymmetric deformations.Comment: 15 pages, latex, 9 postscript figure