210 research outputs found
Bounds on Slow Roll and the de Sitter Swampland
The recently introduced swampland criterion for de Sitter (arXiv:1806.08362)
can be viewed as a (hierarchically large) bound on the smallness of the slow
roll parameter . This leads us to consider the other slow roll
parameter more closely, and we are lead to conjecture that the bound
is not necessarily on , but on slow roll itself. A natural
refinement of the de Sitter swampland conjecture is therefore that slow roll is
violated at in Planck units in any UV complete theory. A
corollary is that need not necessarily be , if
holds. We consider various tachyonic tree level
constructions of de Sitter in IIA/IIB string theory (as well as closely related
models of inflation), which superficially violate arXiv:1806.08362, and show
that they are consistent with this refined version of the bound. The phrasing
in terms of slow roll makes it plausible why both versions of the conjecture
run into trouble when the number of e-folds during inflation is high. We
speculate that one way to evade the bound could be to have a large number of
fields, like in -flation.Comment: v2: many refs added, clarifications and comments added, improved
wording regarding single/multi-field and potential/Hubble slow roll, typos
fixe
Towards a Finite- Hologram
We suggest that holographic tensor models related to SYK are viable
candidates for exactly (ie., non-perturbatively in ) solvable holographic
theories. The reason is that in these theories, the Hilbert space is a spinor
representation, and the Hamiltonian (at least in some classes) can be arranged
to commute with the Clifford level. This makes the theory solvable level by
level. We demonstrate this for the specific case of the uncolored
tensor model with arbitrary even , and reduce the question of determining
the spectrum and eigenstates to an algebraic equation relating Young tableaux.
Solving this reduced problem is conceptually trivial and amounts to matching
the representations on either side, as we demonstrate explicitly at low levels.
At high levels, representations become bigger, but should still be tractable.
None of our arguments require any supersymmetry.Comment: 16 page
3D Gravity, Chern-Simons and Higher Spins: A Mini Introduction
These are notes of introductory lectures on (a) elements of 2+1 dimensional
gravity, (b) some aspects of its relation to Chern-Simons theory, (c) its
generalization to couple higher spins, and (d) cosmic singularity resolution as
an application in the context of flat space higher spin theory. A knowledge of
the Einstein-Hilbert action, classical non-Abelian gauge theory and some
(negotiable amount of) maturity are the only pre-requisites.Comment: 23 pages, Based on talks/lectures by CK at Goteborg, Tehran and
Bangkok. v2:acknowledgments and references added, v3:published versio
Bounds on Slow Roll at the Boundary of the Landscape
We present strong evidence that the tree level slow roll bounds of
arXiv:1807.05193 and arXiv:1810.05506 are valid, even when the tachyon has
overlap with the volume of the cycle wrapped by the orientifold. This extends
our previous results in the volume-dilaton subspace to a semi-universal
modulus. Emboldened by this and other observations, we investigate what it
means to have a bound on (generalized) slow roll in a multi-field landscape. We
argue that for point in an -dimensional field space with
, there exists a path of monotonically decreasing potential
energy to a point within a path length , such
that . The
previous de Sitter swampland bounds are specific ways to realize this stringent
non-local constraint on field space, but we show that it also incorporates (for
example) the scenario where both slow roll parameters are intermediate-valued
and the Universe undergoes a small number of e-folds, as in the Type IIA set up
of arXiv:1310.8300. Our observations are in the context of tree level
constructions, so we take the conservative viewpoint that it is a
characterization of the classical "boundary" of the string landscape. To
emphasize this, we argue that these bounds can be viewed as a type of
Dine-Seiberg statement.Comment: v4: one more referenc
Contrasting SYK-like Models
We contrast some aspects of various SYK-like models with large- melonic
behavior. First, we note that ungauged tensor models can exhibit symmetry
breaking, even though these are 0+1 dimensional theories. Related to this, we
show that when gauged, some of them admit no singlets, and are anomalous. The
uncolored Majorana tensor model with even is a simple case where gauge
singlets can exist in the spectrum. We outline a strategy for solving for the
singlet spectrum, taking advantage of the results in arXiv:1706.05364, and
reproduce the singlet states expected in . In the second part of the
paper, we contrast the random matrix aspects of some ungauged tensor models,
the original SYK model, and a model due to Gross and Rosenhaus. The latter,
even though disorder averaged, shows parallels with the Gurau-Witten model. In
particular, the two models fall into identical Andreev ensembles as a function
of . In an appendix, we contrast the (expected) spectra of AdS quantum
gravity, SYK and SYK-like tensor models, and the zeros of the Riemann Zeta
function.Comment: 45 pages, 17 figures; v2: minor improvements and rearrangements, refs
adde
Massive Scattering Amplitudes in Six Dimensions
We show that a natural spinor-helicity formalism that can describe massive
scattering amplitudes exists in dimensions. This is arranged by having
helicity spinors carry an index in the Dirac spinor {\bf 4} of the massive
little group, . In the high energy limit, two separate kinds
of massless helicity spinors emerge as required for consistency with
arXiv:0902.0981, with indices in the two 's of the massless little group
. The tensors of lead to particles with arbitrary spin, and
using these and demanding consistent factorization, we can fix and
point tree amplitudes of arbitrary masses and spins: we provide examples.
We discuss the high energy limit of scattering amplitudes and the Higgs
mechanism in this language, and make some preliminary observations about
massive BCFW recursion.Comment: 37 pages; v2: minor improvements, JHEP versio
Strings vs Spins on the Null Orbifold
We study the null orbifold singularity in 2+1 d flat space higher spin theory
as well as string theory. Using the Chern-Simons formulation of 2+1 d Einstein
gravity, we first observe that despite the singular nature of this geometry,
the eigenvalues of its Chern-Simons holonomy are trivial. Next, we construct a
resolution of the singularity in higher spin theory: a Kundt spacetime with
vanishing scalar curvature invariants. We also point out that the UV
divergences previously observed in the 2-to-2 tachyon tree level string
amplitude on the null orbifold do not arise in the
limit. We find all the divergences of the amplitude and demonstrate that the
ones remaining in the tensionless limit are physical IR-type divergences. We
conclude with a discussion on the meaning and limitations of higher spin
(cosmological) singularity resolution and its potential connection to string
theory.Comment: 27 pages, 5 figures, v2: comments about boundary conditions added,
strengthening the conclusio
Development of moringa infusion for green tea and its evaluation
Moringa oleifera leaves are known for its high nutritional quality. Its leaves are commonlyused for culinary purposes and it was explored as a potential nutraceutical in recent decades.Tea or herbal infusions have become an integral part of daily diet for a population who concernedabout a healthy lifestyle. Many herbs or plant parts have been used as infusions which providehealth promoting phytochemicals to the consumers. Therefore moringa infusions were preparedalong with some herbs/flavouring agents such as tulsi, ginger and lemon grass. Total polyphenolcontent in the infusions ranged between 685 and 1567 mg GAE/100 mL. Among phenolic acidsdetected, gallic acid was highest in all the treatments. Infusion containing moringa and tulsiscored high in organoleptic evaluation. Thus, moringa infusion can become an add-on varietyto the tea/herbal infusion consumers
- …