28 research outputs found
Tetraquark states and spectrum
A general classification of tetraquark states in terms of the spin-flavour,
colour and spatial degrees of freedom has been constructed. The permutational
symmetry properties of both the spin-flavour and orbital parts of the
quark-quark and antiquark-antiquark subsystems are discussed in short. This
classification is model indipendent and useful both for model-builders and
experimentalists. An evaluation of the tetraquark spectrum is obtained from a
generalization of a Iachello mass formula, originally developed for the mesons. The ground state tetraquark nonet is identified with ,
, , .Comment: Invited talk at XI Conference on Problems in Theoretical Nuclear
Physics (Cortona 2006), Cortona, Italy, 11-14 Oct, 200
Photoproduction of Z(4430) through mesonic Regge trajectories exchange
The recently discovered Z(4430) mesonic resonance is believed to be a strong
tetraquark candidate. The photoproduction in the channel has been proposed as the most
effective way to confirm the Z(4430) presence and to measure its quantum
numbers. In this work we present a model for high energy and forward angle
Z(4430) photoproduction in a effective Lagrangian approach. This model is based
on the use of Regge trajectories exchange, thus a Regge propagator replaces the
usual Feynman propagator. The differential and total cross sections and the
asymmetries have been calculated for the quantum numbers ,
, and in the hypotheses that Z(4430) has isospin I=1
Gluelump spectrum from Coulomb gauge QCD
We compute the energy spectrum of gluelumps defined as gluonic excitations
bound to a localized, static octet source. We are able to reproduce the
nontrivial ordering of the spin-parity levels and show how this is related to
the non-abelian part of the Coulomb interaction between color charges.Comment: 8 pages, 5 figure
Heavy quarkonium hybrids from Coulomb gauge QCD
Using the non-relativisitc reduction of Coulomb gauge QCD we compute spectrum
of the low mass hybrid mesons containing a heavy quark-antiquark pair. The
gluon degrees of freedom are treated in the mean field approximation calibrated
to the gluelump spectrum. We discuss the role of the non-abelian nature of the
QCD Coulomb interaction in the ordering of the spin-parity levels.Comment: 12 pages, 6 figure
Tetraquark spectroscopy
A complete classification of tetraquark states in terms of the spin-flavor,
color and spatial degrees of freedom was constructed. The permutational
symmetry properties of both the spin-flavor and orbital parts of the
quark-quark and antiquark-antiquark subsystems are discussed. This complete
classification is general and model-independent, and is useful both for
model-builders and experimentalists. The total wave functions are also
explicitly constructed in the hypothesis of ideal mixing; this basis for
tetraquark states will enable the eigenvalue problem to be solved for a
definite dynamical model. This is also valid for diquark-antidiquark models,
for which the basis is a subset of the one we have constructed. An evaluation
of the tetraquark spectrum is obtained from the Iachello mass formula for
normal mesons, here generalized to tetraquark systems. This mass formula is a
generalizazion of the Gell-Mann Okubo mass formula, whose coefficients have
been upgraded by means of the latest PDG data.
The ground state tetraquark nonet was identified with ,
, , . The mass splittings predicted by
this mass formula are compared to the KLOE, Fermilab E791 and BES experimental
data. The diquark-antidiquark limit was also studied.Comment: Invited talk at 11th International Conference on Meson-Nucleon
Physics and the Structure of the Nucleon (MENU 2007), Julich, Germany, 10-14
Sep 2007. In the Proceedings of 11th International Conference on
Meson-Nucleon Physics and the Structure of the Nucleon (MENU 2007), Julich,
Germany, 10-14 Sep 2007, eConf C070910, 163 (2007
Electromagnetic analysis of the plasma chamber of an ECR-based charge breeder.
The optimization of the efficiency of an ECR-based charge breeder is a twofold task: efforts must be paid to maximize the capture of the injected 1+ ions by the confined plasma and to produce high charge states to allow post-acceleration at high energies. Both tasks must be faced by studying in detail the electrons heating dynamics, influenced by the microwave-to-plasma coupling mechanism. Numerical simulations are a powerful tools for obtaining quantitative information about the wave-to-plasma interaction process: this paper presents a numerical study of the microwaves propagation and absorption inside the plasma chamber of the PHOENIX charge breeder, which the selective production of exotic species project, under construction at Legnaro National Laboratories, will adopt as charge breeder. Calculations were carried out with a commercial 3D FEM solver: first, all the resonant frequencies were determined by considering a simplified plasma chamber; then, the realistic geometry was taken into account, including a cold plasma model of increasing complexity. The results gave important information about the power absorption and losses and will allow the improvement of the plasma model to be used in a refined step of calculation reproducing the breeding process itself
Rescheduling rehabilitation sessions with answer set programming
The rehabilitation scheduling process consists of planning rehabilitation physiotherapy sessions for patients, by assigning proper operators to them in a certain time slot of a given day, taking into account several requirements and optimizations, e.g. patient’s preferences and operator’s work balancing. Being able to efficiently solve such problem is of upmost importance, in particular as a consequence of the COVID-19 pandemic that significantly increased rehabilitation’s needs. The problem has been recently successfully solved via a two-phase solution based on answer set programming (ASP). In this paper, we focus on the problem of rescheduling the rehabilitation sessions, which comes into play when the original schedule cannot be implemented, for reasons that involve the unavailability of operators and/or the absence of patients. We provide rescheduling solutions based on ASP for both phases, considering different scenarios. Results of experiments performed on real benchmarks, provided by ICS Maugeri, show that also the rescheduling problem can be solved in a satisfactory way. Finally, we present a web application that supports the usage of our solution
An ASP-based Approach to Master Surgical Scheduling.
The problem of finding Master Surgical Schedules (MSS) consists of scheduling different specialties to
the operating rooms of a hospital clinic. To produce a proper MSS, each specialty must be assigned to
some operating rooms. The number of assignments is different for each specialty and can vary during the
considered planning horizon. Realizing a satisfying schedule is of upmost importance for a hospital clinic.
A poorly scheduled MSS may lead to unbalanced specialties availability and increase patients’ waiting list,
negatively affecting both the administrative costs of the hospital and the patient satisfaction. In this paper,
we present a compact solution based on Answer Set Programming (ASP) to the MSS problem. We tested
our solution on different scenarios: experiments show that our ASP solution provides satisfying results in
short time, also when compared to other logic-based formalisms. Finally, we describe a web application
we have developed for easy usage of our solution