122704344
Mesonic structure in the nucleon
120768053
Dips in one-pion production processes from a statistical point of view
118409646
Superfluidity of hadronic matter
SummaryThe mesons in the nucleon are associated with a Bose system with an energy excitation spectrum ε(p), wherep is the corresponding momentum. This spectrum can be investigated by studying the nucleon recoil in one-meson production processes. It turns out that
$$\mathop {\lim }\limits_{p \to 0} (\varepsilon /p) \ne 0$$
. This is the Landau criterion for superfluidity. Herefrom we infer that hadronic matter is superfluid. Possible manifestations of this phenomenon in strong interactions are a bootstrap relation between the masses of mesonic and baryonic resonances, the shift of the δ-resonance in nuclei, the existence of a maximum resonance mass equivalent to an ionization point and the existence of a critical temperature of hadronic matter instead of a maximum temperature.RiassuntoI mesoni nel nucleone sono associati per mezzo di un sistema di bose con uno spettro di energie di eccitazione ε(p), dovep è l'impulso corrispondente. Si può analizzare questo spettro studiando il rinculo del nucleone nei processi di produzione di un mesone. Risulta che
$$\mathop {\lim }\limits_{p \to 0} (\varepsilon /p) \ne 0$$
. Questo è il criterio di landau per la superfluidità. Da ciò si inferisce che la materia adronica è superfluida. Possibili manifestazioni di questo fenomeno nelle interazioni forti sono una relazione di bootstrap fra le masse delle risonanze mesoniche e barioniche, lo spostamento della risonanza δ nei nuclei, l'esistenza di una massa massima della risonanza equivalente ad un punto di ionizzazione e l'esistenza di una temperatura critica della materia adronica invece di una temperatura massima.РезюмеМезоны в нуклоне связываутся с Гозе-системой с энергетическим спектром возбуждения ε(p), гдеp есть соответствующии импульс. Этот спектр может быть исследован посредством изучения отдачи нуклона в процессе рождения одного пиона. Оказывается, что
$$\mathop {\lim }\limits_{p \to 0} (\varepsilon /p) \ne 0$$
. Это представляет критерий Ландау для сверхтекучести, из которого мы делаем вывод, что адронное вещество является сверхтекучим. Возможные проявления этого явления в сильных взаимодействиях представляют: соотношения бутстрепа между массами мезонных и барионных резонансов, сдвиг δ резонанса в ядрах, существование резонансной массы, эквивалентной точке ионизации, и существование критической температуры адронного вещества вместо максимальной темпатуры.
123483448
Probing the weak force with neutrinos
Interest in neutrino physics has surged up recently, partly because the “little neutral ones” are being groomed for the job (for which they alone are qualified) of probing the interiors of stars. Among elementary particles the neutrino is unique. This is because—as far as we know—it alone interacts with other particles only through the Fermi, or weak, interaction. In this article we will discuss how recent experiments, with new accelerators and detectors, such as the ones at CERN and Fermi Lab, have shed new light on some of the fundamental questions regarding the weak interactions. We will review the recent discoveries of neutral weak currents that conserve strangeness, parity violation and point‐like neutrino collisions, as well as some of the implications of these experiments to particle theory.
121989655
Further observation of dimuon production by neutrinos
By using a quadrupole focused neutrino beam, 61 events with two muons in the final state have been observed at Fermilab. These include seven $mu$$sup - $$mu$$sup -$ events. A comparison of the event rate in two targets of different hadron absorption length indicates that attributing the events to $pi$ or K leptonic decay is ruled out by 4.0 standard deviations. No trimuon events were observed; this circumstance, combined with lepton conservation, indicates an unobserved neutral lepton is present in most of the events. (AIP)
122918733
Observation of Elastic Neutrino and Antineutrino Scattering and Parity Violation in the Weak Hadronic Neutral Current
We have observed 30 events of the process νp → νp with a background expectation of 7 events. The ratio σ(νp → νp)/σ(νn → μ −p) is measured to be 0.17 ± 0.05 for 0.3 <q2 <0.9 (GeV/c)2 where — q2 is the square of the four-momentum transfer to the proton. We have also observed 22 events of the process νp → νp with a background expectation of 8 events. The ratio σ(νp → νp)/σ(νp → μ +n) is 0.2 ± 0.1 for the same q2 interval. These two measurements yield a ratio σ(νp → νp)/σ(νp → νp) = 0.4 ± 0.2, where the error is statistical. This difference between neutrino and antineutrino scattering suggests that the hadronic neutral current displays a significant parity-violating interference and that a purely vector Lorentz structure is unlikely.
42017178
Casimir's entropy
The classical `Kirchhoff's theorem' (the energy density of the radiation at equilibrium at high temperature, T, is a function of T only) is used to obtain the Casimir energy at zero temperature without recourse to regularization. The validity of `Kirchhoff's theorem' at the high-temperature limit for the case at hand is confirmed. The Casimir entropy is defined and its temperature dependence is displayed. The Casimir entropy at high temperatures is shown to approach a positive geometry-dependent but temperature-independent constant.
8636737
The universal sampling ADC readout system of the COMPASS experiment
The COMPASS experiment (COmpact Muon Proton Apparatus for Structure and Spectroscopy) is a fixed target experiment located at the CERN Super Proton Synchrotron. The physics program is focused on the study of hadron structure and hadron spectroscopy with high intensity muon and hadron beams, up to 160 GeV/c for muons and 190 GeV/c for hadrons respectively. To allow the tracking of charged particles with very low and as well very high momentum, COMPASS comprises two magnetic spectrometer stages extending to a total length of 60 m. From the data acquisition point of view, about 200000 analog detector channels have to be read along the complete experiment. Depending on the detector signal characteristics and the number of channels, this task is realized by frontend electronics using either dedicated ASICs and/or sampling analog-to-digital (ADC) or time-to-digital (TDC) components. The sampling ADC based readout system of the COMPASS experiment comprises today over 127k channels equipped with the APV25 frontend ASIC and 5728 direct sampling channels. An important feature from the beginning was the combination of data transfer, clock and trigger distribution and configuration access within a standardized serial interface between the different ADC modules and the first stage of data concentrator modules. By choosing between a copper or fiber realization for this interface, either a low cost interconnect or a link with galvanic decoupling can be realized. The ongoing development of the sampling ADC electronics is focused on the migration toward the Advanced Telecom Computing Architecture (ATCA) crate standard, to overcome the backplane bandwidth limitations in VME systems. In addition, the ATCA standard provides better cooling and monitoring capabilities. To simplify the transition to ATCA, the MSADC module was already realized as a mezzanine card, which can be mounted on an ATCA based carrier card as well. In addition, the MSADC card fits also to the MicroTCA form factor, which allows to provide a handy building block for laboratory based data acquisition systems.