arXiv subjects
Publications and source records attributed to E. Cattaruzza.
In this paper we show that, via an extension of time, some metric structures naturally appear in both classical and quantum mechanics when both are formulated via path integrals. We calculate the various Ricci scalar and curvatures associated to these metrics and prove that they can be choosen to be zero in classical mechanics while this is not possible in quantum mechanics.
In this paper we show how to obtain from a scalar superfield its first component via a similarity transformation. We prove that in D=4 the generators of this similarity transformation live in the enveloping algebra of supersymmetry while for D=1 they belong to the basic algebra.
In this paper we show that the energy eigenstates of supersymmetric quantum mechanics (SUSYQM) with non definite "fermion" number are entangled states. They are "physical states" of the model provided that observables with odd number of spin variables are allowed in the theory like it happens in the Jaynes-Cummings model. Those states generalize the so called "spin spring" states of the Jaynes-Cummings model which have played an important role in the study of entanglement.
In this paper we show how the equations of motion of a superfield, which makes its appearance in a path-integral approach to classical mechanics, can be derived without the need of the least-action principle
Multiple parton collisions will represent a rather common feature in pp collisions at the LHC, where regimes with very large momentum transfer may be studied and events rare in lower energy accelerators might occur with a significant rate. A reason of interest in large p_t regimes is that, differently from low p_t, evolution will induce correlations in x in the multiparton structure functions. We have estimated the cross section of multiple production of W bosons with equal sign, where the correlations in x induced by evolution are particularly relevant, and the cross section of b-bar_b b-bar_b production, where the effects of evolution are much smaller. Our result is that, in the case of multiple production of W bosons, the terms with correlations may represent a correction of the order of 40% of the cross sections, for pp collisions at 1 TeV c.m. energy, and a correction of the order of 20% at 14 TeV. In the case of b-bar_b pairs the correction terms are of the order of 10-15% at 1 TeV and of the order of 5% at 14 TeV.
The color screening in a QCD plasma, that was studied in a formulation making evident similarities and differences with the electric case, is continued by taking into account the contributions of real gluons. The results, which include a numerical analysis not previously performed, show a damping of the correlation function which, if not exponential, does not differ very much from that form. The role of the temperature, which affect both the population and the dynamics of the quark-gluon system, is found to be relevant.
We evaluate the Cronin effect in pA collisions at the CERN LHC and at RHIC in the framework of Glauber-Eikonal model of initial state multiparton interactions. Taking carefully into account all kinematical constraints of each multi-parton interaction process we obtain a softening of the spectrum of produced partons, improving in this way the agreement of the model with the recent measurements of pi0 production in d+Au collisions at sqrt{s}=200 AGeV.
A sizable rate of events, with several pairs of $b$-quarks produced contemporarily by multiple parton interactions, may be expected at very high energies as a consequence of the large parton luminosities. The production rates are further enhanced in hadron-nucleus reactions, which may represent a convenient tool to study the phenomenon. We compare the different contributions to $b{\bar b}b{\bar b}$ production, due to single and double parton scatterings, in collisions of protons with nuclei at the CERN-LHC.
In the study of multiple scattering of partons in hadron-hadron collisions the possibility of a hard inelastic process at the parton level is included in its simplest possible way, $i.e.$ including the $2 \to 3$ transition. The specific physical process to which the treatment is applied is the inelastic collision of a nucleon with a heavy nucleus