325 research outputs found

    Properties of the phi meson at high temperatures and densities

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    We calculate the spectral density of the phi meson in a hot bath of nucleons and pions using a general formalism relating self-energy to the forward scattering amplitude (FSA). In order to describe the low energy FSA, we use experimental data along with a background term. For the high energy FSA, a Regge parameterization is employed. We verify the resulting FSA using dispersion techniques. We find that the position of the peak of the spectral density is slightly shifted from its vacuum position and that its width is considerably increased. The width of the spectral density at a temperature of 150 MeV and at normal nuclear density is more than 90 MeV.Comment: 4 pages, 5 figures, Poster presented at Quark Matter 200

    Is it possible to formulate least action principle for dissipative systems?

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    A longstanding open question in classical mechanics is to formulate the least action principle for dissipative systems. In this work, we give a general formulation of this principle by considering a whole conservative system including the damped moving body and its environment receiving the dissipated energy. This composite system has the conservative Hamiltonian H=K1+V1+H2H=K_1+V_1+H_2 where K1K_1 is the kinetic energy of the moving body, V1V_1 its potential energy and H2H_2 the energy of the environment. The Lagrangian can be derived by using the usual Legendre transformation L=2K1+2K2−HL=2K_1+2K_2-H where K2K_2 is the total kinetic energy of the environment. An equivalent expression of this Lagrangian is L=K1−V1−EdL=K_1-V_1-E_d where EdE_d is the energy dissipated by the friction from the moving body into the environment from the beginning of the motion. The usual variation calculus of least action leads to the correct equation of the damped motion. We also show that this general formulation is a natural consequence of the virtual work principle.Comment: 11 pages, no figur

    Linkages between Cigarette Smoking Outcome Expectancies and Negative Emotional Vulnerability

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    The present investigation examined whether smoking outcome expectancies, as measured by the Smoking Consequences Questionnaire (SCQ; [Brandon, T.H., & Baker, T.B., (1991). The Smoking Consequences Questionnaire: The subjective expected utility of smoking in college students. Psychological Assessment, 3, 484–491.]), were incrementally related to emotional vulnerability factors among an adult sample of 202 daily cigarette smokers (44.6% women; Mage= 23.78 years, SD = 9.69 years). After controlling for cigarettes smoked/day, past 30-day marijuana use, current alcohol consumption, and coping style, negative reinforcement/negative affect reduction outcome expectancies were significantly associated with greater levels of negative affectivity, emotional dysregulation, and anxiety sensitivity. The observed effects for negative reinforcement/negative affect reduction also were independent of shared variance with other outcome expectancies. Negative personal consequences outcome expectancies were significantly and incrementally related to anxiety sensitivity, but not negative affectivity or emotional dysregulation. Findings are discussed in terms of the role of negative reinforcement/ negative affect reduction smoking outcome expectancies and clinically-relevant negative emotional vulnerability for better understanding cigarette smoking-negative mood problem
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