11,543 research outputs found
Generalised connections and higher-spin equations
We consider high-derivative equations obtained setting to zero the divergence
of the higher-spin curvatures in metric-like form, showing their equivalence to
the second-order equations emerging from the tensionless limit of open string
field theory, which propagate reducible spectra of particles with different
spins. This result can be viewed as complementary to the possibility of setting
to zero a single trace of the higher-spin field strengths, which yields an
equation known to imply Fronsdal's equation in the compensator form. Higher
traces and divergences of the curvatures produce a whole pattern of
high-derivative equations whose systematics is also presented.Comment: 12 pages, minor change
Low-spin models for higher-spin Lagrangians
Higher-spin theories are most commonly modelled on the example of spin 2.
While this is appropriate for the description of free irreducible spin-s
particles, alternative options could be equally interesting. In particular
Maxwell's equations provide the effective model for maximally reducible
theories of higher spins inspired by the tensionless limit of the open string.
For both options, as well as for their fermionic counterparts, one can extend
the analogy beyond the equations for the gauge potentials, formulating the
corresponding Lagrangians in terms of higher-spin curvatures. The associated
non-localities are effectively due to the elimination of auxiliary fields and
do not modify the spectrum. Massive deformations of these theories are also
possible, and in particular in this contribution we propose a generalisation of
the Proca Lagrangian for the Maxwell-inspired geometric theories.Comment: 12 pages, PTPTeX. Contribution to the proceedings of the 3rd
International Conference on String Field Theory and Related Aspects (SFT
2010), Kyoto, Japan, 18-22 Oct 201
String theory triplets and higher-spin curvatures
Unconstrained local Lagrangians for higher-spin gauge theories are bound to
involve auxiliary fields, whose integration in the partition function generates
geometric, effective actions expressed in terms of curvatures. When applied to
the triplets, emerging from the tensionless limit of open string field theory,
the same procedure yields interesting alternative forms of geometric
Lagrangians, expressible for both bosons and fermions as squares of
field-strengths. This shows that higher-spin curvatures might play a role in
the dynamics, regardless of whether the Fronsdal-Labastida constraints are
assumed or forgone.Comment: 14 pages. Eqs. (2.13) and (3.7) added. Footnotes 8 and 14 and
corresponding references included. Additional minor changes. To appear in
Phys. Lett.
Performance of Hispanic-Owned Businesses in Nacogdoches, Texas
Hypothesis
The Hispanic business owners have an increasing potential to become big businesses in the East Texas town because of the growth of the Hispanic population in tow
Synergistic effects of cardiac resynchronization therapy and drug up-titration in heart failure. is this enough?
This editorial refers to ‘Optimization of heart failure medication after cardiac resynchronization therapy and the impact on long-term survival’, by C.T. Witt et al., on
page 18
Cubic interactions of massless higher spins in (A)dS: metric-like approach
Cubic interactions of higher-spin gauge fields in (A)dS are studied in the
metric-like approach. Making use of the traceless and transverse constraints
together with the ambient-space formalism, all consistent parity-invariant
cubic vertices are obtained for d>3 in closed form pointing out the key role of
their flat-space counterparts.Comment: 33 pages, LaTex. Final version to appear in NP
Safety, Efficacy and Evidence Base for Use of the Subcutaneous Implantable Cardioverter Defibrillator
The trans-venous implantable cardioverter defibrillator (TV-ICD) is effective in treating life-threatening ventricular arrhythmia and reduces mortality in high-risk patients. However, there are significant short- and long-term complications that are associated with intravascular leads. These shortcomings are mostly relevant in young patients with long life expectancy and low risk of death from non-arrhythmic causes. Drawbacks of trans-venous leads recently led to the development of the entirely subcutaneous implantable cardioverter defibrillator (S-ICD). The S-ICD does not require vascular access or permanent intravascular defibrillation leads. Therefore, it is expected to overcome many complications associated with conventional ICDs. This review highlights data on safety and efficacy of the S-ICD and is envisioned to help in identifying the role of this device in clinical practice
Bessel beam through a dielectric slab at oblique incidence: the case of total reflection
The oblique incidence of a Bessel beam on a dielectric slab with refractive
index n1 surrounded by a medium of a refractive index n>n1 may be studied
simply by expanding the Bessel beam into a set of plane waves forming the same
angle with the axis of the beam. In the present paper we examine a Bessel beam
that impinges at oblique incidence onto a layer in such a way that each
plane-wave component impinges with an angle larger than the critical angle.Comment: 10 pages, 6 figure
On higher-spin supertranslations and superrotations
We study the large gauge transformations of massless higher-spin fields in
four-dimensional Minkowski space. Upon imposing suitable fall-off conditions,
providing higher-spin counterparts of the Bondi gauge, we observe the existence
of an infinite-dimensional asymptotic symmetry algebra. The corresponding Ward
identities can be held responsible for Weinberg's factorization theorem for
amplitudes involving soft particles of spin greater than two.Comment: Motivations and clarifications added. Matches published versio
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