9,726 research outputs found
Two loops calculation in chiral perturbation theory and the unitarization program of current algebra
In this paper we compare two loop Chiral Perturbation Theory (ChPT)
calculation of pion-pion scattering with the unitarity second order correction
to the current algebra soft-pion theorem. It is shown that both methods lead to
the same analytic structure for the scattering amplitude.Comment: 13 pages, Revtex 3.0, no figures, submitted to Phys. Lett.
New family of potentials with analytical twiston-like solutions
In this letter we present a new approach to find analytical twiston models.
The effective two-field model was constructed by a non-trivial combination of
two one field systems. In such an approach we successfully build analytical
models which are satisfied by a combination of two defect-like solutions, where
one is responsible to twist the molecular chain by , while the other
implies in a longitudinal movement. Such a longitudinal movement can be fitted
to have the size of the distance between adjacent molecular groups. The
procedure works nicely and can be used to describe the dynamics of several
other molecular chains.Comment: 7 pages, 3 figure
A Snapshot Semester: Students’ Reflections of Performance and Mental State throughout a Graduate Course
Graduate students are anecdotally reputed to be among the most stressed groups of young adults. Common sources of stress for graduate students have included coursework, assistantships, finances, career preparation, and family (Wyatt & Oswalt, 2013; Mazzola, Walker, Shockley & Spector, 2011; Oswalt & Riddock, 2007). Guided reflection can be used by educators to assist students in both learning (Boud, Keogh & Walker, 2013; Kolb, 1984) and managing stress (Shoulders, Whitehead, & Morrison, 2018). By understanding how students’ progress through a semester in terms of both their learning and their management of stress, instructors and academic advisors can better anticipate times of struggle among their students, giving them greater opportunity to meet their students’ needs with appropriate guidance and instruction. This study explored students’ perceptions of their performance and mental state throughout a semester-long course.
The purpose of this study was to explore graduate students’ perceptions of their own academic and coping experiences throughout a Research Methods course. The purpose was fulfilled by the following research questions: 1) how do students perceive their engagement with course content as a piece in their holistic lives? 2) how do online versus FTF students perceive their engagement with course content as a piece in their holistic lives?
Students enrolled in the Fall 2018 Research Methods in the Social Sciences at the University of Arkansas (N = 43) were assigned to submit weekly visual reflections that portrayed their relationship with the class, along with a written justification for the image selected. Students submitted the visual reflection on Friday for 16 weeks in the semester. Data was analyzed using a constant comparative method (Glaser, 1965).
From these reflections, 130 themes were identified from the 16 weeks. Nine overarching themes were then developed over the entirety of the semester. Once a holistic description of each theme throughout the semester was completed, the students were grouped as online or face-to-face (FTF) students. Each theme was re-examined to group them based on their association with online students, FTF students, or both. By examining these experiences, professors can better prepare their teaching methods to match students’ needs
Diffraction and an infrared finite gluon propagator
We discuss some phenomenological applications of an infrared finite gluon
propagator characterized by a dynamically generated gluon mass. In particular
we compute the effect of the dynamical gluon mass on and
diffractive scattering. We also show how the data on photoproduction
and hadronic reactions can be derived from the and
forward scattering amplitudes by assuming vector meson dominance and
the additive quark model.Comment: 4 pages, 7 figures, added references and figures, changed structure.
Contribution to Proceedings of XVIIIth Reuniao de Trabalho sobre Interacoes
Hadronicas, Sao Paulo, Brazil, 22-24 May, 200
Pion-Pion Phase-Shifts and the Value of Quark-Antiquark Condensate in the Chiral Limit
We use low energy pion-pion phase-shifts in order to make distinction between
the alternatives for the value of the quark-antiquark condensate in the
chiral limit. We will consider the amplitude up to and including contributions within the Standard and Generalized Chiral Perturbation
Theory frameworks. They are unitarized by means of Pad\'e approximants in order
to fit experimental phase-shifts in the resonance region. As the best fits
correspond to , we conclude that pion-pion phase-shift
analysis favors the standard ChPT scenario, which assumes just one, large
leading order parameter .Comment: 5 pages, 3 figures and 1 tabl
Two Superconducting Phases in CeRh_1-xIr_xIn_5
Pressure studies of CeRh_1-xIr_xIn_5 indicate two superconducting phases as a
function of x, one with T_c >= 2 K for x < 0.9 and the other with T_c < 1.2 K
for x > 0.9. The higher T_c phase, phase-1, emerges in proximity to an
antiferromagnetic quantum-critical point; whereas, Cooper pairing in the lower
T_c phase-2 is inferred to arise from fluctuations of a yet to be found
magnetic state. The T-x-P phase diagram of CeRh_1-xIr_xIn_5, though
qualitatively similar, is distinctly different from that of
CeCu_2(Si_1-xGe_x)_2.Comment: 5 pages, 3 figure
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