Triangle Seminars
Tuesday, 11 Feb 2020
Learning about the Planck scale: Marginal couplings and the predictive power of scale invariance
Aaron Held
(Imperial College London)
Abstract:
I will review the current status of the asymptotic safety program,
focusing on the predictive power of scale invariance, followed by a
collection of results on how the Standard-Model couplings may be used to
constrain physics at the Planck scale. At a time in which collider
measurements collect increasing evidence that the Standard Model as an
effective field theory is consistent up to the Planck scale, its
marginal couplings offer a unique opportunity to learn about quantum
gravity.
I will also briefly introduce a research program aimed at constraining
the marginal couplings of the gravitational sector, i.e.,
curvature-squared terms, via black-hole stability and binary mergers.
I will review the current status of the asymptotic safety program,
focusing on the predictive power of scale invariance, followed by a
collection of results on how the Standard-Model couplings may be used to
constrain physics at the Planck scale. At a time in which collider
measurements collect increasing evidence that the Standard Model as an
effective field theory is consistent up to the Planck scale, its
marginal couplings offer a unique opportunity to learn about quantum
gravity.
I will also briefly introduce a research program aimed at constraining
the marginal couplings of the gravitational sector, i.e.,
curvature-squared terms, via black-hole stability and binary mergers.
Posted by: IC
Wednesday, 12 Feb 2020
Amplitudes meet Cosmology
📍 London
Paolo Benincasa
(NBI)
Abstract:
The principles of Lorentz invariance, locality and unitarity highly
constrain the physics at accessible high energy: the type of
interactions allowed as well as most of the theorems known in particle
physics are instances of these principles. This is neatly seen in the
structure of scattering amplitudes in asymptotically flat space-times.
However, cosmology suggests that such principles may be just
approximate: Lorentz invariance is broken at cosmological scales and the
accelerated expansion of the universe seems to prevent a full-fledge
definition of quantum mechanical observables. If our fundamental ideas
in particle physics become somehow approximate in cosmology, what are
the fundamental rules governing cosmological processes?
In this talk I will report on a recent program which aims to address
this question, by bringing both philosophy and methods which have been
successful for scattering amplitudes to the analysis of cosmological
observables. In particular we investigate the analytic properties of the
perturbative wavefunction of the universe, how fundamental physics
is encoded into it, how the flat-space physics reflects into it, and how
all these features are encoded into new mathematical structures, which
can be used as a novel first principle definition of the perturbative
wavefunction.
The principles of Lorentz invariance, locality and unitarity highly
constrain the physics at accessible high energy: the type of
interactions allowed as well as most of the theorems known in particle
physics are instances of these principles. This is neatly seen in the
structure of scattering amplitudes in asymptotically flat space-times.
However, cosmology suggests that such principles may be just
approximate: Lorentz invariance is broken at cosmological scales and the
accelerated expansion of the universe seems to prevent a full-fledge
definition of quantum mechanical observables. If our fundamental ideas
in particle physics become somehow approximate in cosmology, what are
the fundamental rules governing cosmological processes?
In this talk I will report on a recent program which aims to address
this question, by bringing both philosophy and methods which have been
successful for scattering amplitudes to the analysis of cosmological
observables. In particular we investigate the analytic properties of the
perturbative wavefunction of the universe, how fundamental physics
is encoded into it, how the flat-space physics reflects into it, and how
all these features are encoded into new mathematical structures, which
can be used as a novel first principle definition of the perturbative
wavefunction.
Posted by: KCL
TBA
Evgeny Sobko
(Southampton)
Abstract:
TBA
TBA
Posted by: IC
Thursday, 13 Feb 2020
O(d,d) covariant string cosmology to all orders in alpha'
Guilherme Franzmann
(NORDITA)
Abstract:
Recently, all duality invariant α′ (alpha-prime)-corrections to the massless NS-NS sector of string theory on time-dependent backgrounds were classified and the form of their contribution to the action were calculated. In this talk we will see how to introduce matter sources in the resulting equations of motion in an O(d,d) covariant way. Then we show that either starting with the corrected equations and sourcing them with matter or considering corrections to the matter sourced lowest order equations give the same set of equations that defines string cosmology to all orders in α′. We also discuss perturbative and non-perturbative de Sitter solutions including matter, and explicitly show that de Sitter solutions are allowed non-perturbatively.
Recently, all duality invariant α′ (alpha-prime)-corrections to the massless NS-NS sector of string theory on time-dependent backgrounds were classified and the form of their contribution to the action were calculated. In this talk we will see how to introduce matter sources in the resulting equations of motion in an O(d,d) covariant way. Then we show that either starting with the corrected equations and sourcing them with matter or considering corrections to the matter sourced lowest order equations give the same set of equations that defines string cosmology to all orders in α′. We also discuss perturbative and non-perturbative de Sitter solutions including matter, and explicitly show that de Sitter solutions are allowed non-perturbatively.
Posted by: QMW