2,155 research outputs found
On structure of effective action in four-dimensional quantum dilaton supergravity
A general structure of effective action in new chiral superfield model
associated with , supergravity is investigated. This model
corresponds to finite quantum field theory and does not demand the
regularization and renormalization at effective action calculation. It is shown
that in local approximation the effective action is defined by two objects
called general superfield effective lagrangian and chiral superfield effective
lagrangian. A proper-time method is generalized for calculation of these two
effective lagrangians in superfield manner. Power expansion of the effective
action in supercovariant derivatives is formulated and the lower terms of such
an expansion are calculated in explicit superfield form
The Background Field Method for N = 2 Super Yang-Mills Theories in Harmonic Superspace
The background field method for N=2 super Yang-Mills theories in harmonic
superspace is developed. The ghost structure of the theory is investigated. It
is shown that the ghosts include two fermionic real omega-hypermultiplets
(Faddeev-Popov ghosts) and one bosonic real omega-hypermultiplet
(Nielsen-Kallosh ghost), all in the adjoint representation of the gauge group.
The one-loop effective action is analysed in detail and it is found that its
structure is determined only by the ghost corrections in the pure super
Yang-Mills theory. As applied to the case of N=4 super Yang-Mills theory,
realized in terms of N=2 superfields, the latter result leads to the remarkable
conclusion that the one-loop effective action of the theory does not contain
quantum corrections depending on the N=2 gauge superfield only. We show that
the leading low-energy contribution to the one-loop effective action in the N=2
SU(2) super Yang-Mills theory coincides with Seiberg's perturbative holomorphic
effective action.Comment: 17 pages, Late
Ionization corrections in a multi-phase interstellar medium: Lessons from a z~2 sub-DLA
We present a high resolution (FWHM=2.7 km/s), high S/N echelle spectrum for
the z = 2.26 QSO J2123-0050 and determine elemental abundances for the z = 2.06
sub-DLA in its line of sight. This high redshift sub-DLA has a complex
kinematic structure and harbours detections of neutral (SI, CI), singly (e.g.
CII, SII) and multiply ionized (e.g. CIV, SiIV) species as well as molecular H
and HD. The plethora of detected transitions in various ionization stages is
indicative of a complex multi-phase structure present in this high redshift
galaxy. We demonstrate that the ionization corrections in this sub-DLA are
significant (up to ~0.7 dex). For example, if no ionization correction is
applied, a super-solar metallicity is derived ([S/H] = +0.36), whereas a single
phase ionization correction reduces this to [S/H] = -0.19. The theoretical
impact of a multi-phase medium is investigated through Cloudy modelling and it
is found that the abundances of Si, S and Fe are always over-estimated (by up
to 0.15 dex in our experiments) if a single-phase is assumed. Therefore,
although Cloudy models improve estimates of metal column densities, the
simplification of a single phase medium leaves a systematic error in the
result, so that even ionization-corrected abundances may still be too high.
Without ionization corrections the properties of this sub-DLA appear to require
extreme scenarios of nucleosynthetic origins. After ionization corrections are
applied the ISM of this galaxy appears to be similar to some of the sightlines
through the Milky Way.Comment: Accepted for publication in MNRA
Correlation function of circular Wilson loop with two local operators and conformal invariance
We consider the correlation function of a circular Wilson loop with two local
scalar operators at generic 4-positions in planar N=4 supersymmetric gauge
theory. We show that such correlator is fixed by conformal invariance up to a
function of 't Hooft coupling and two scalar combinations of the positions
invariant under the conformal transformations preserving the circle. We compute
this function at leading orders at weak and strong coupling for some simple
choices of local BPS operators. We also check that correlators of an infinite
line Wilson loop with local operators are the same as those for the circular
loop.Comment: 26 pages. v2: reference added, misprints correcte
Standardised method for reporting exercise programmes : protocol for a modified Delphi study
Introduction Exercise is integral to health across the lifespan and important for people with chronic health conditions. A systematic review of exercise trials for chronic conditions reported suboptimal descriptions of the evaluated interventions and concluded that this hinders interpretation and replication. The aim of this project is to develop a standardised method for reporting essential exercise programme details being evaluated in clinical trials.
Methods and analysis A modified Delphi technique will be used to gain consensus among international exercise experts. We will use three sequential rounds of anonymous online questionnaires to refine a standardised checklist. A draft checklist of potentially relevant items was developed based on the results of a systematic review of exercise systematic reviews. An international panel of experts was identified by exercise systematic review authorship, established international profile in exercise research and practice and by peer referral. In round 1, the international panel of experts will be asked to rate the importance of each draft item and provide additional suggestions for revisions or new items. Consensus will be considered reached if at least 70% of the panel strongly agree/disagree that an item should be included or excluded. Where agreement is not reached or there are suggestions for altered or new items, these will be taken to round 2 together with an aggregated summary of round 1 responses. Following the second round, a ranking of item importance will be made to rationalise the number of items. The final template will be distributed to panel members for approval.
Ethics and dissemination Ethics approval was received from The Cabrini Institute Ethics Committee, Melbourne, Australia (HREC 02-07-04-14). We plan to use a stepwise process to develop and refine a standardised and internationally agreed template for explicit reporting of exercise programmes. The template will be generalisable across all types of exercise interventions. The findings will be disseminated through peer-reviewed publications and conference presentations
Covariant Harmonic Supergraphity for N = 2 Super Yang--Mills Theories
We review the background field method for general N = 2 super Yang-Mills
theories formulated in the N = 2 harmonic superspace. The covariant harmonic
supergraph technique is then applied to rigorously prove the N=2
non-renormalization theorem as well as to compute the holomorphic low-energy
action for the N = 2 SU(2) pure super Yang-Mills theory and the leading
non-holomorphic low-energy correction for N = 4 SU(2) super Yang-Mills theory.Comment: 17 pages, LAMUPHYS LaTeX, no figures; based on talks given by I.
Buchbinder and S. Kuzenko at the International Seminar ``Supersymmetries and
Quantum Symmetries'', July 1997, Dubna; to be published in the proceeding
The Dynamics of Small Instanton Phase Transitions
The small instanton transition of a five-brane colliding with one end of the
S1/Z2 interval in heterotic M-theory is discussed, with emphasis on the
transition moduli, their potential function and the associated non-perturbative
superpotential. Using numerical methods, the equations of motion of these
moduli coupled to an expanding Friedmann-Robertson-Walker spacetime are solved
including non-perturbative interactions. It is shown that the five-brane
collides with the end of the interval at a small instanton. However, the moduli
then continue to evolve to an isolated minimum of the potential, where they are
trapped by gravitational damping. The torsion free sheaf at the small instanton
is ``smoothed out'' into a vector bundle at the isolated minimum, thus
dynamically completing the small instanton phase transition. Radiative damping
at the origin of moduli space is discussed and shown to be insufficient to trap
the moduli at the small instanton point.Comment: LaTeX, 23 pages, 7 figures; minor corrections, references adde
- …