The symmetries of the tree level string effective action are discussed. An appropriate effective action is constructed starting from the manifestly SL(2,R) invarint form of string effective action ...introduced by Schwarz and Sen. The conserved charges are derived and generators of infinitesimal transformations are obtained in the Hamiltonian formalism. Some interesting consequences of the canonical transformations are explored.
Classical solutions for a four-dimensional Minkowskian string effective action and an Euclidean one with cosmological constant term are derived. The former corresponds to electrovac solutions whereas ...the later solutions are identified as gravitational instanton solutions for Fubini-Study metric. The symmetries of the effective actions are identified and new classical solutions are generated by implementing appropriate noncompact transformations. The S-duality transformations on the equations of motion are discussed and it is found that they are S-duality noninvariant due to the presence of cosmological constant term.
We revisit general arguments for the absence of exact continuous global symmetries in string compactifications and extend them to D-brane models. We elucidate the various ways approximate continuous ...global symmetries arise in the 4-dimensional effective action. In addition to two familiar methods - axionic Peccei-Quinn symmetries and remnant global abelian symmetries from Green-Schwarz gauge symmetry breaking - we identify new ways to generate approximate continuous global symmetries. Two methods stand out, both of which occur for local brane constructions within the LARGE volume scenario of moduli stabilisation. The first is the generic existence of continuous non-abelian global symmetries associated with local Calabi-Yau isometries. These symmetries are exact in the non-compact limit and are spontaneously broken by the LARGE volume, with breaking effects having phenomenologically interesting sizes \sim 0.01 for plausible choices for underlying parameters. Such approximate flavour symmetries are phenomenologically attractive and may allow the fermion mass hierarchies to be connected to the electroweak hierarchy via the large volume. The second is the possible existence of new hyper-weak gauge interactions under which Standard Model matter is charged, with \alpha_{HW} \sim 10^{-9}. Such groups arise from branes wrapping bulk cycles and intersecting the local (resolved) singularity on which the Standard Model is supported. We discuss experimental bounds for these new gauge bosons and their interactions with the Standard Model particles.
First results from the WA98 experiment on 33 TeV
208Pb ion reactions with various targets measured at the CERN SPS are presented. Data on transverse energy production and particle multiplicity are ...discussed. Special emphasis is laid on photon and neutral meson production.
C. porosus usually guards the nest from one or more wallows. Nest-guarding is not a continuous process and in the present study on a captive female, occupied 75% of the total observation period. The ...crocodile retreated to the pool in the early hours of the morning and also during the day, presumably on thermoregulatory considerations. Absences were usually of short duration, mean 1.46 hours. Nest-guarding occurred from different sites. The implications for management are discussed.
Nucl.Phys.B390:3-32,1993 Noncompact groups, similar to those that appeared in various supergravity
theories in the 1970's, have been turning up in recent studies of string
theory. First it was ...discovered that moduli spaces of toroidal compactification
are given by noncompact groups modded out by their maximal compact subgroups
and discrete duality groups. Then it was found that many other moduli spaces
have analogous descriptions. More recently, noncompact group symmetries have
turned up in effective actions used to study string cosmology and other
classical configurations. This paper explores these noncompact groups in the
case of toroidal compactification both from the viewpoint of low-energy
effective field theory, using the method of dimensional reduction, and from the
viewpoint of the string theory world sheet. The conclusion is that all these
symmetries are intimately related. In particular, we find that Chern--Simons
terms in the three-form field strength $H_{\mu\nu\rho}$ play a crucial role.
Phys.Lett. B374 (1996) 43-48 The S-duality invariance of the equations of motion of four dimensional
string effective action with cosmological constant, $\Lambda $, is studied. It
is demonstrated ...that the S-duality symmetry of the field equations are broken
for nonzero $\Lambda$. The ``naturalness'' hypothesis is invoked to argue that
$\Lambda $ should remain small since exact S-duality symmetry will force the
cosmological constant to vanish in the string effective action.
The significance of the Wess--Zumino term in spin tunneling is explored, and
a formula is established for the splitting of energy levels of a particle with
large fermionic spin as an applied magnetic ...field is switched on.
Noncompact groups, similar to those that appeared in various supergravity theories in the 1970's, have been turning up in recent studies of string theory. First it was discovered that moduli spaces ...of toroidal compactification are given by noncompact groups modded out by their maximal compact subgroups and discrete duality groups. Then it was found that many other moduli spaces have analogous descriptions. More recently, noncompact group symmetries have turned up in effective actions used to study string cosmology and other classical configurations. This paper explores these noncompact groups in the case of toroidal compactification both from the viewpoint of low-energy effective field theory, using the method of dimensional reduction, and from the viewpoint of the string theory world sheet. The conclusion is that all these symmetries are intimately related. In particular, we find that Chern--Simons terms in the three-form field strength \(H_{\mu\nu\rho}\) play a crucial role.
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