Ohio State University
Technische Universität München
North Carolina State University
Technische Universität München
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INT Program INT-18-1b|
Multi-Scale Problems Using Effective Field Theories
May 7 - June 1, 2018
There are many interesting open problems at the frontiers of nuclear
and particle physics that are characterized by the existence of a
separation of scales that can be exploited using effective field
theories (EFTs). The EFT method treats the low-energy degrees of
freedom as dynamical fields, and takes into account higher-energy
scales systematically through matching conditions. The choice of
the low-energy degrees of freedom that remain dynamical depends
on the physical observables we wish to describe.
Many state-of-the-art applications of EFT involve multiple effective
field theories to deal with several different scales. Examples include
sequences of EFTs in which the dynamical degrees of freedom have
increasingly lower energies. Other applications involve very different
EFTs that are combined in innovative ways to systematically separate
EFT methods developed in high energy and nuclear physics have been
applied successfully in other fields, such as atomic, molecular, and solid
state physics. Many-body systems involving multiple scales are of interest
to physicists from many backgrounds, and new avenues for studying these
systems in very clean settings have recently emerged in condensed matter
physics and especially in atomic physics.
This interdisciplinary program will focus on addressing
multi-scale problems in various areas of physics using multiple
effective field theories with the aim to bring together EFTs practitioners
from a large span of physical problems.
An innovative and original aspect of our program is the synergy created
by bringing together scientists working in diverse areas of physics
using the unifying methodology of EFTs.
It is clear that progress in many of these areas is
critically dependent on bringing
together EFT practitioners with overlapping interests but different
specialized expertise, which is the goal of our program.
In addition to spinning off results from EFTs in nuclear and particle physics to related problems
in atomic, molecular and condensed matter physics, we want to develop EFT descriptions for nonperturbative physics in collaboration with lattice gauge theorists.
The program seeks to bring together researchers with diverse backgrounds
in nuclear, particle, atomic, and condensed matter physics,
as well as quantum optics and computational physics. The program will have
around 16 participants at any given time. Participants will be invited
to present their work during informal morning talks. Each morning,
we will arrange two talks by researchers from different
fields introducing physically related topics from different perspectives.
In addition, we will organize two weekly afternoon discussions with subjects
related to the presentations.
We specify below a focus for each of the four weeks of the program.
Each focus represents a specific multi-scale application of EFT where we
believe significant progress can be made.
We hope to attract multiple participants actively working on the focus area
However the program each week will maintain an emphasis on the broad
applicability of effective field theories.
Week 1: Transport
There is a hierarchy of scales in real-time correlation
functions that can be used to connect an underlying
microscopic field theory to kinetic theory and fluid
dynamics. Questions on this framework include: can we perform the required matching calculations
in higher order, and can we define them non-perturbatively?
What is the role of real-time classical simulations? Can
we view dissipative, stochastic fluid dynamics as an EFT?
Week 2: Dark matter
The physics of dark matter may well involve multiple scales.
The important scales for wimps include the wimp mass,
the weak boson masses, and wimp mass splittings,
and they can differ by orders of magnitude.
The important scales for axions involve its decay constant, its mass,
and its width, and they can differ by tens of orders of magnitude.
EFT can be used to separate the scales in order to simplify
theoretical treatments and sharpen phenomenological predictions.
EFT can also provide model-independent frameworks for addressing
dark-matter problems. This focus week will highlight recent progress
in applying EFT to dark matter and hopefully stimulate further progress
on constraining the nature of the dark-matter particle.
Week 3: Open quantum systems
Non-equilibrium processes appear in a large span of physical problems
ranging from high energy physics and cosmology, to heavy ion physics
and atomic and condensed matter physics.
Examples include the loss of ultracold trapped atoms due to
highly inelastic reactions, the evolution of quarkonium in the Quark Gluon
the decay of heavy Majorana neutrinos in the hot environment of the early
Recently an open quantum system approach based on the underlying effective
field theory and on Lindblad equations have been developed in some cases.
This focus week will highlight the recent progress and promote new ideas
and further development with an interdisciplinary discussion bringing
together various physics communities.
Week 4: Exotic states
In hadron and nuclear physics, resonances and
composite objects with various natures and with interactions at the pion scale are
very prominent in experiments and in theory discussions.
The X, Y, Z states observed at collider experiments are
tetraquark mesons and pentaquark baryons, whose constituents include a
heavy quark and antiquark.
Nonrelativistic EFTs have been developed to describe
such hadrons whose masses are well below the heavy-meson pair threshold. The
threshold region is more challenging, because it introduces additional scales.
A promising approach is based on the EFT of the
Born-Oppenheimer expansion, which has been
extremely successful in atomic and molecular physics.
We will also discuss the development of novel EFTs for such systems,
together with related lattice calculations, in a cross talk among atomic,
molecular, nuclear and particle physicists.