122046947
ARES — a spectrometer for the investigation of rare particle decays and rare nuclear processes
Abstract A magnetic spectrometer intended for a wide range of investigations of rare particle and nuclear processes is described. The spectrometer consists of cylindrical proportional chambers (∼ 15000 signal wires) with gas supply and gas leakage systems, cylindrical scintillation hodoscopes, a magnet, electronics with power supplies, and a data acquisition system. Basic characteristics of the spectrometer are discussed and results of first physics experiments are presented.
119270809
Detector with a profile-based cathode and the two-coordinate pad-strip readout system
A detector with a profile-based cathode and a two-coordinate cathode readout system has been experimentally investigated. Cathode pads located in each profile along the anode wire are diagonally interconnected, thus forming strips that cross the detector at some angle with respect to the anode wire. Owing to the availability of the two cathode coordinates and the coordinate associated with the anode wire, it is possible to solve the problem of identifying high-multiplicity events in a single detector.
121235164
Architecture of data-acquisition systems for high-energy physics experiments
In this review we discuss the evolution of the basic principles of the architecture of data-acquisition systems for experimental setups used in high-energy physics and relativistic nuclear physics during the last 25 years. The effect of the latest advances in computational techniques and communications, such as microprocessors and open bus system standards, on improving data recording and acquisition is discussed. The evolution of data-acquisition systems is illustrated by examples of developments occurring at the leading physics centers and at the Laboratory of High Energy Physics, JINR, Dubna. The trends in the future development of data-acquisition systems are described for the research programs at the LHCcollider, CERN, and the Relativistic Heavy Ion Collider at Brookhaven National Laboratory.
15373665
Analytical results for dimensionally regularized massless on-shell double boxes with arbitrary indices and numerators
Abstract We present an algorithm for the analytical evaluation of dimensionally regularized massless on-shell double box Feynman diagrams with arbitrary polynomials in numerators and general integer powers of propagators. Recurrence relations following from integration by parts are solved explicitly and any given double box diagram is expressed as a linear combination of two master double boxes and a family of simpler diagrams. The first master double box corresponds to all powers of the propagators equal to one and no numerators, and the second master double box differs from the first one by the second power of the middle propagator. By use of differential relations, the second master double box is expressed through the first one up to a similar linear combination of simpler double boxes so that the analytical evaluation of the first master double box provides explicit analytical results, in terms of polylogarithms Li a −t/s , up to a=4, and generalized polylogarithms Sa,b(−t/s), with a=1,2 and b=2, dependent on the Mandelstam variables s and t, for an arbitrary diagram under consideration.
16910552
Threshold behavior of Feynman diagrams: the master two-loop propagator
Abstract An asymptotic expansion of the two-loop two-point “master” diagram with two masses m and M , on the mass shell Q 2 = M 2 , is presented. The treatment of the non-analytical terms arising in the expansion around the branching point is discussed. Some details of the calculation of a new class of two-loop integrals are given.
14720899
Evaluating double and triple (?) boxes
A brief review of recent results on analytical evaluation of double-box Feynman integrals is presented. First steps towards evaluation of massless on-shell triple-box Feynman integrals within dimensional regularization are described. The leading power asymptotic behaviour of the dimensionally regularized massless on-shell master planar triple-box diagram in the Regge limit ts → 0 is evaluated. The evaluation of the unexpanded master planar triple box is outlined and explicit results for coefficients at 1ϵj, j=2, …, 6, are presented.
16236109
Potential NRQCD and heavy-quarkonium spectrum at next-to-next-to-next-to-leading order
Abstract The next-to-next-to-next-to-leading order (N 3 LO) Hamiltonian of potential nonrelativistic QCD is derived. The complete matching of the Hamiltonian and the contribution from the ultrasoft dynamical gluons relevant for perturbative bound-state calculations is performed including one-, two-, and three-loop contributions. The threshold expansion is used to disentangle and match contributions of different scales in the effective-theory calculations. As a physical application, the heavy-quarkonium spectrum is obtained at N 3 LO for the case of vanishing QCD beta function. Our results set the stage for a full N 3 LO analysis of the heavy-quarkonium system.