Classical behaviour of Q-balls in the Wick-Cutkosky model

In this paper, we continue discussing Q-balls in the Wick--Cutkosky model. Despite Q-balls in this model are composed of two scalar fields, they turn out to be very useful and illustrative for examining various important properties of Q-balls. In particular, in the present paper we study in detail (analytically and numerically) the problem of classical stability of Q-balls, including the nonlinear evolution of classically unstable Q-balls, as well as the behaviour of Q-balls in external fields in the non-relativistic limit.Comment: 21 pages, 12 figures, LaTeX; v2: section 3.3 slightly enlarged, typos corrected, minor changes in the tex

LHCb trigger streams optimization

The LHCb experiment stores around $10^{11}$ collision events per year. A typical physics analysis deals with a final sample of up to $10^7$ events. Event preselection algorithms (lines) are used for data reduction. Since the data are stored in a format that requires sequential access, the lines are grouped into several output file streams, in order to increase the efficiency of user analysis jobs that read these data. The scheme efficiency heavily depends on the stream composition. By putting similar lines together and balancing the stream sizes it is possible to reduce the overhead. We present a method for finding an optimal stream composition. The method is applied to a part of the LHCb data (Turbo stream) on the stage where it is prepared for user physics analysis. This results in an expected improvement of 15% in the speed of user analysis jobs, and will be applied on data to be recorded in 2017.Comment: Submitted to CHEP-2016 proceeding

Stress-strain state and loss of stability of anisotropic thermal coating under thermal shock

The deformation behavior of thermal barrier coatings has been investigated. The mechanism of occurring instabilities in such coatings based on their representation in the form of a plate located on an elastic foundation has been studied. Loss of stability manifests itself in the form of a doubly periodic system of intrusion and extrusion zones that is qualitatively consistent with the well-known experimental results. Typical features of stability loss and its dependence on the properties of conjugated materials have been investigated by the example of the thermal loading simulation of the copper specimen with a protective ceramic coating. The influence of the thermo-mechanical properties anisotropy of the coating material on the character of the emerging instability has been estimated

Equivariant pretheories and invariants of torsors

In the present paper we introduce and study the notion of an equivariant pretheory: basic examples include equivariant Chow groups, equivariant K-theory and equivariant algebraic cobordism. To extend this set of examples we define an equivariant (co)homology theory with coefficients in a Rost cycle module and provide a version of Merkurjev's (equivariant K-theory) spectral sequence for such a theory. As an application we generalize the theorem of Karpenko-Merkurjev on G-torsors and rational cycles; to every G-torsor E and a G-equivariant pretheory we associate a graded ring which serves as an invariant of E. In the case of Chow groups this ring encodes the information concerning the motivic J-invariant of E and in the case of Grothendieck's K_0 -- indexes of the respective Tits algebras.Comment: 23 pages; this is an essentially extended version of the previous preprint: the construction of an equivariant cycle (co)homology and the spectral sequence (generalizing the long exact localization sequence) are adde

Increasing Fatigue LIfe of 09Mn2Si Steel by means of High-Temperature Multistep Helical Rolling

The effect of high temperature helical rolling (HR) on structure and fatigue life of 09Mn2Si pipe steel has been studied. With the use of transmission electron microscopy there was revealed that rolling gives rise to refinement of ferrite grains and cracking (fracturing) of cementite plates within the pearlite phase. The effect manifests itself to the greatest extent in the surface layer where due to the rolling the level of plastic deformation was the highest. Data of microhardness measurements confirms the gradient pattern of strain hardening over the cross section during the HR occurs while the most intensive microhardness increasing take place at the depth of up to 3 mm. According to the mechanical testing results the helical rolling of 09Mn2Si steel gives rise to increasing the level of deforming stress at the yield plateau as well as the proportionality limit with a general decrease in the relative elongation. At the same time, despite the strain hardening resulting from the helical rolling the mechanisms of plastic deformation which manifest themselves in the form of parabolic hardening with a smooth decrease in the flow stress level after neck formation are preserved in the steel. During the cyclic tension the number of cycles prior to failure increases from 2.5 to 3.8 times that depends on the location of specimens' cutting from the rolled rod. The highest improvement in fatigue fracture resistance is registered for specimens cut out from the core of the rolled rods