123581677
LINEARIZED VERSION OF THE HARTREE--FOCK METHOD.
122704344
Mesonic structure in the nucleon
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.
123621331
APPROACH TO THE NUCLEAR MANY-BODY PROBLEM BY VARIATIONALLY DETERMINED TRANSFORMATION. II.
We present a generalization of the Hartree-Fock (HF) method incorporating two-body correlations. The correlations are introduced by means of a unitary operator ${e}^{\mathrm{iF}}$, where $F$ is a Hermitian one- and two-body operator to be determined by the variational principle. Assuming that the matrix elements of $F$ are small so that powers of $F$ higher than the second may be neglected, a set of linear equations determining $F$ is obtained. The relation between our method and methods used to treat singular interactions is discussed. The method is applied to two recently suggested models and is compared with the HF method, second-order perturbation theory, and with the random-phase approximation. It is found that our method yields very good results within the range of validity of our approximations, which seems to call forth applications to more realistic problems. Possible applications to the study of collective phenomena in nuclei are indicated.
122236095
APPROACH TO THE NUCLEAR MANY-BODY PROBLEM BY A VARIATIONALLY DETERMINED TRANSFORMATION.
122239911
Maximumvs. Critical temperature in a superfluid approach to strong interactions
123016244
Observation of new particle production by high energy neutrinos and antineutrinos
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.
119280331
Calorimeter-Based Triggers at the ATLAS Detector for Searches for Supersymmetry in Zero-Lepton Final States
This thesis consists of three closely related parts. An analysis of data recorded by the ATLAS detector in 2010 in proton-proton collisions at a center-of-mass energy of 7 TeV with an integrated luminosity of 33.4 pb-1 is performed, searching for supersymmetric final states containing jets and missing transverse energy and no electrons or muons (zero-lepton channel). No excess over the Standard Model background expectation is observed. Using the CLs and PLR methods, exclusion limits are set in a minimal supergravity model with tan β = 3, A0 = 0 GeV and μ > 0 and in a simplified supergravity model. These considerably extend the excluded parameter ranges from earlier experiments. The analysis validates the official analysis carried out within the ATLAS Supersymmetry group and additionally takes into account the uncertainty from pile-up effects.The rates and efficiencies of triggers based on combined signatures with jets plus missing transverse energy in ATLAS are studied, which are the primary triggers for the search for Supersymmetry in the zero-lepton channel. Methods to measure the efficiencies on data are tested and optimized to obtain sufficient statistics. For the measurement of the efficiencies in data collected in 2010 and 2011, the bootstrap method is applied to correct for the sample trigger bias. Different sample triggers based on jets and missing transverse energy are compared and their efficiencies are measured. A reweighting approach is studied and used to correct for the bias from the propagation of the uncertainties in the bootstrap method. The resulting efficiency estimates for the primary triggers allow to determine the onset of the plateau of the two-dimensional turn-on curves and are input to the official analyses in the ATLAS Supersymmetry group in 2010 and 2011.A universal model is developed to describe the contribution of fake missing transverse energy from resolution effects to the rates of missing transverse energy triggers as function of the level of in-time pile-up, i.e. the number of concurrent proton-proton interactions. The input parameters to tune the model to the properties of the ATLAS triggers are determined, and the model predictions are compared to measurements of trigger rates in ATLAS. Good agreement is found for missing transverse energy triggers with low thresholds for which the rates are dominated by resolution effects, whereas the rates for higher thresholds are underestimated due to additional sources of fake and real missing transverse energy which are not incorporated in the model.
123939432
Measurement of the radiative electron polarization in a 2.4 GeV storage ring
We have observed the existence of transverse polarization of the electron beam in the SPEAR storage ring resulting from the emission of synchrotron radiation in the magnetic field. The time constant for polarization build-up has been measured for a single circulating electron beam to be approx. 90 min and the corresponding equilibrium polarization to be approx. 0.85. These values are to be compared with the theoretical predictions of 124 min and 0.924, respectively. (AIP)
20903628
Repulsive Casimir forces.
We discuss repulsive Casimir forces between dielectric materials with nontrivial magnetic susceptibility. It is shown that considerations based on the naive pairwise summation of van der Waals and Casimir-Polder forces may not only give an incorrect estimate of the magnitude of the total Casimir force but even the wrong sign of the force when materials with high dielectric and magnetic responses are involved. Indeed repulsive Casimir forces may be found in a large range of parameters, and we suggest that the effect may be realized in known materials. The phenomenon of repulsive Casimir forces may be of importance both for experimental study and for nanomachinery applications.