* denotes the organizer responsible for participant diversity in the workshop

May 26 – September 15
Individual Research

Physicists are encouraged to apply as individual researchers to work on their own projects for up to five weeks at any time during the summer. We provide a serene atmosphere to complete work. The individual researcher may also choose to attend any workshop meetings or chat with other scientists in residence in addition to working on his or her own research. Click here for more information.

May 26 – September 15
Working Group

Working groups of between two and six physicists are encouraged. Click here for more information.

May 26 - June 30
Physics of Functional Biological Assemblies: Pushing, Pulling and Sensing
Ajay Gopinathan, University of California, Merced
Fred MacKintosh, Vrije University
Jennifer Ross*, University of Massachusetts
David Sept,
Washington University

Biology provides many rich examples of complex and adaptive materials. Cellular systems, in particular, pose fundamental challenges that arise from their non-equilibrium nature and their hierarchical structures. Cytoskeletal filaments, for example, that occur in conjunction with motors and associated proteins are extremely versatile and can display a wide range of dynamically self-assembled structures including radially organized filaments, bundles, cross-linked networks, networks of bundles, membrane associated two dimensional networks and even liquid crystalline phases depending on context and function. Cytoskeletal assemblies govern spatial organization within the cell, the production and transmission of forces, serving as physical and chemical links to the external world and serving as a network for intracellular transport. Function in this system emerges from the interplay between the mechanical properties, dynamics, interactions and biochemical regulation of the constituent elements – providing a fertile ground for applying physical principles to biologically relevant problems and for uncovering new unanticipated physics in these active, dynamic and functional materials.

While we have learnt a significant amount about the physics of these systems, the next hurdle is to relate this more closely to cellular function. We believe the time is ripe to address this challenge by hosting a workshop that can bring together theoretical physicists, experimental biophysicists and cell biologists. This will enable the identification of current theoretical and computational challenges, as well as key questions that need to be addressed by quantitative, physics-based experiments. A five-week workshop focusing on the physical basis of function in these remarkable assemblies should therefore provide a foundation for innovative new cross-disciplinary approaches.

May 26 - June 16
Lattice Gauge Theory in the LHC Era
Simon Catterall, University of Syracuse
Paul Damgaard, Niels Bohr Institute
Anna Hasenfratz*, University of Colorado
Yannick Meurice, University of Iowa

The goal of the workshop is to bring together lattice gauge theorists involved in the study of various non-perturbative aspects of what is called Physics Beyond the Standard Model. These include alternatives or modifications of the standard Higgs mechanism, supersymmetry, and electroweak precision tests, all of which require non-perturbative lattice studies. Beyond Standard Model investigations are a major program at the Large Hadron Collider (LHC), and given the timeline for the experimental effort at the LHC, this workshop is very timely. There are two principal ways to search for Physics Beyond the Standard Model; direct exploration and indirect searches for signals via precision calculations of observables in the Standard Model. In the former case, lattice gauge theorists have in recent years established programs to study candidate both composite Higgs theories such as technicolor and also supersymmetric gauge theories. In the latter case, there is a well established program in the lattice gauge theory community to provide precision calculations of strong interaction effects in weak matrix elements. By comparison with experiment such calculations can yield signs of Beyond Standard Model Physics.

May 26 - June 16
The Origins of Stellar Clustering: From Fragmenting Clouds to the Build-Up of Galaxies
Nate Bastian, Excellence Cluster Universe
Diederik Kruijssen*, Max Planck Institute for Astrophysics
Mark Krumholz, University of California, Santa Cruz
Steve Longmore,
European Southern Observatory

Some fraction of all stars is formed in gravitationally bound stellar clusters, while the remainder originates in unbound associations. It is not understood which physical mechanisms generate either result. Recent work indicates that the outcome of the star/cluster formation process may already be set by the characteristics of the interstellar medium at the onset of gravitational collapse. If true, this provides a promising ansatz to identify the physics of cluster formation: the conversion of gas into stellar clusters. With the new generation of observational facilities such as Herschel, ALMA, Gaia, and JWST, it will be possible to follow the time evolution of the entire star formation process, from the structure of the interstellar medium and the initial collapse of giant molecular clouds to the emergence of massive, dense stellar clusters. The insights that will follow from these observations can be interpreted in the context of galaxy formation and evolution, allowing an understanding of how the galaxy-scale environment and small-scale star formation events are influenced by each other.

By bringing together experts in the theory and observations of the physics of the interstellar medium, star/cluster formation, cluster populations, and star cluster/galaxy evolution, this workshop is intended to make significant progress in understanding the wide range of scales and mechanisms that govern the star and cluster formation process. The three weeks of the workshop will include the following themes. Throughout, there will be a natural focus on how to direct the theory, numerical work, and observations to meet on common grounds.

1) The current theoretical understanding of star and cluster formation
- How do collapsing giant molecular clouds (GMCs) fragment and convert their gas into stars?
- Which feedback mechanisms halt star formation, and how does the resulting gas expulsion affect the formation of stellar clusters?
- How do the global characteristics of galaxies influence the properties of GMCs and clustered star formation?

2) Observational constraints on star and cluster formation
- How well can the progenitors of stellar clusters currently be identified in the interstellar medium (ISM)?
- Which observational methods can be used to determine the gravitational boundedness of young stellar structure?
- What do galaxies other than the Milky Way tell us about the variation of stellar clustering with the galactic environment?

3) Connecting the dots: towards an understanding of stellar clustering
- Where do the small-scale and galaxy-scale physics of star formation meet and how should both be combined in a complete picture of cluster formation?
- How will the recent and upcoming observational facilities enable us to constrain the physics of cluster formation?
- How can we address the variation of stellar clustering with cosmic time?
- What can we learn about globular cluster formation by considering star and cluster formation in the nearby universe?

May 26 - June 16
The Obscured Universe: Dust and Gas in Distant Starburst Galaxies
Andrew Benson, Carnegie Observatories
Caitlin Casey, University of Hawaii
Asantha Cooray*, University of California, Irvine
Olivier Dore, Jet Propulsion Laboratory
Alexandra Pope, University of Massachusetts
Dominik Riechers, Caltech

The goal of this workshop is to bring together observers, theorists, and experimentalists who study the cosmic infrared background and the associated dusty starburst galaxies in the universe from today to the epoch of reionization. Existing facilities such as the Herschel, ALMA, and ground-based instruments and interferometers have now discovered large samples of dusty galaxies and are starting to probe their physical details with multi-wavelength data. These facilities have begun to provide detailed observations related to gas, dust and stars of galaxies during their peak activity which can be used to improve existing theoretical models of dusty star formation. Future facilities such as CCAT and LMT will make further improvements in our understanding of the universe at sub-mm wavelengths. Existing studies with Planck, SPT and ACT suggest that these dusty galaxies generate an important secondary CMB anisotropy signal and its characterization would be crucial for a variety of CMB studies. The preliminary Herschel results show that sub-mm surveys can identify large samples of lensed sub-mm galaxies with efficiency close to 100% - thereby providing a wealth of cosmological information.

A summary of topics to be discussed during the workshop follows:
* Sub-mm galaxy properties: dust production, the initial mass function of the stars, AGN activity, gas-rich mergers vs. cold flow accretion, gas consumption, the trigger and shut-off mechanisms that form and destroy the starburst phenomenon in galaxies, connection between theoretical models.
* Sub-mm survey statistics: sub-mm surveys from Herschel to CMB experiments, clustering, lensing, first SMGs in the universe at z~6, redshift distribution, multi-wavelength properties of sub-mm galaxies;
* Future: planned surveys and instruments, novel measurement techniques at sub-mm wavelengths from space and beyond. 

June 16 - July 7
The Next Decade of Weak Lensing Science
Bhuvnesh Jain, University of Pennsylvania
Alexie Leauthaud, Kavli Institute for the Physics and Mathematics of the Universe
Rachel Mandelbaum*, Carnegie Mellon University
Ludo van Waerbeke, University of British Columbia

The scientific promise of weak gravitational lensing (WL) has inspired a number of very ambitious observational programs starting in 2012/2013 (KIDS, Pan-STARRS, HSC, DES), and several more to begin in about a decade from now (LSST, Euclid). These surveys will cover an order of magnitude more sky area than most existing ones (thousands of square degrees of sky rather than hundreds), and due to the greater statistical power, better control of systematic errors is also required. The WL community therefore must learn as much as possible from existing data in order to focus its efforts for the next generation surveys, both to reduce the main sources of systematic error and to develop more sophisticated ways of handling outstanding theoretical issues.

In the past few years, there has been extensive development in WL theory, observations, and numerical simulations. The field of WL now reaches such a maturity and level of complexity that future surveys will benefit considerably from tighter connections between the different areas. We envision a workshop that will establish strong and durable connection between observers who focused on the previous generation of lensing surveys, those working on the next generation, and theorists. The ultimate goal is to guide the efforts of those working on the next generation surveys, which will include thorough discussion of ways to minimize and characterize systematic errors (through hardware, software, and careful survey design) that plagued previous surveys, and development of theoretical techniques to get the most information from the data while minimizing sensitivity to any residual systematics.

Among the observational systematics under discussion will be robust measurement of galaxy shapes under realistic imaging conditions; and estimation of photometric redshifts (line-of-sight distances to galaxies using broad-band photometry) to get redshift estimates for all galaxies, and the use of spectroscopic surveys for calibration purposes.

Another equally important aspect is data reduction of very large data sets and data mining, more specifically what future surveys can learn from computer science techniques and high energy physics to deal with the ever increasing data flow.

Among the theoretical topics of discussion are intrinsic alignments of galaxy shapes (due to, e.g. local tidal fields - which can mimic a lensing signal); optimal ways to distinguish between dark energy and modifications of the theory of gravity; and minimization of theoretical uncertainties in the observables, e.g. due to the (currently) poorly known effects of baryons (luminous matter).

Regarding numerical simulations, the topics of discussion will include the important question of small-scale modeling of the dark matter power spectrum and its sensitivity to baryonic physics such as AGN, supernovae winds and other feedback mechanisms.

The workshop will allow a significant amount of time for informal discussions and the development of new research collaborations.

June 16 - July 21
Disorder, Dynamics, Frustration and Topology in Quantum Condensed Matter
Cristian Batista, Los Alamos National Laboratory
Joel Moore, University of California, Berkeley
Gil Refael*, Caltech
Nandini Trivedi, Ohio State University
Ali Yazdani, Princeton

Taken independently, disorder leads to quantum interference and localization, interactions to Mott and Wigner insulators, and spin-orbit coupling to topological band insulators. What is the result, however, of combining topology with interactions and disorder? What is the nature of new states of matter induced by topology in interacting systems and the quantum phase transitions between them? How do disorder effects, such as localization, modify dynamics in interacting systems, and to what extent does topological protection still apply? Similarly, the effects of disorder and defects is far from clear in frustrated interacting quantum systems, which give rise to exotic phases such as spin-liquids, or Fermi-liquid with incommensurate order. The aim of the workshop will be to foster discussion of the ideas, experiments and techniques that could help us overcome these broad challenges.

July 7 - August 4
Mathematics of Superconformal Field Theory
Daniel Freed, University of Texas
Gregory Moore, Rutgers University
Andrew Neitzke, University of Texas
Hirosi Ooguri*, Caltech

Superconformal field theory is a topic of current significant activity in both the math and physics communities. This workshop has two focal points: the (2,0)-superconformal field theory in six dimensions and the scattering amplitudes of N=4 super Yang-Mills theory in four dimensions. These two subjects have been the loci of dramatic developments in the last few years. Moreover, there are tantalizing indications that they are actually linked.

Very few interacting quantum field theories are known in dimensions greater than four. Doubtless the most fascinating of these is the (2,0)-superconformal field theory in six dimensions, first conjectured to exist in 1995 based on string theory arguments. The mere existence of the (2,0)-theory has fantastic consequences for more familiar, lower-dimensional theories. There are deep connections to pure mathematics as well. Despite the remarkable applications of the existence of the six-dimensional superconformal theories, there is no systematic construction of these theories from first principles, not even at a physicist's level of mathematical rigor. Several different approaches have been suggested, but none has been entirely successful. One goal of the workshop is to bring together people working on these different approaches to the foundation of the subject. In particular, recent advances in the mathematical structure of topological and conformal field theory are likely to play an important role in this endeavor.

N=4 super Yang-Mills is the most supersymmetric quantum field theory in four dimensions. Textbook methods for studying the theory make it look forbiddingly complex, but recently there is evidence from many different perspectives that the theory has a deeper underlying integrability. This integrability is visible even in the most basic quantities derived from the theory: scattering amplitudes. The traditional procedure at weak coupling via Feynman integrals is forbiddingly laborious. Powerful new methods for computing these amplitudes both at weak and strong coupling have been developed over the last few years, combining ideas from all over the map: twistors, Yangian symmetry, holography, multidimensional residue calculus, number theory, and cluster algebras. These methods have vastly expanded the horizon of what can be computed. The answers, moreover, turn out to be simpler than they have any real right to be. This points to new fundamental organizing principles---perhaps for quantum field theory in general---an enticing possibility to be explored in the workshop.

Some of the new mathematical tools used in the computation of perturbative amplitudes, most notably cluster algebras and cluster varieties, have also found prominent applications in investigations of the new superconformal field theories mentioned in the previous section. This suggests that there are further deep relations between the new insights in (2,0)-theories and the new methods in computing perturbative amplitudes.

July 21 - August 11
The Milky Way as a Laboratory for Galaxy Formation
Kathryn Johnston*, Columbia University
Andrey Kravtsov, University of Chicago
Constance Rockosi, UCO/Lick Observatory
Monica Valluri, University of Michigan
Mark Wilkinson, University of Leicester

Formation of luminous stellar components of galaxies within the context of hierarchical structure formation remains one of the main unsolved problems in astrophysics today.

This workshop will bring together observers, simulators, modelers and theorists to focus on how current and future resolved star surveys of the Milky Way can be used to reconstruct the structure and formation history of the Galaxy in a cosmological context. The questions addressed at this workshop will include
(a) How can detailed stellar dynamical modeling be used to estimate the density of dark matter in the vicinity of the Sun (influencing direct dark matter detection experiments on Earth), as well as the global shape and density distribution of Galactic dark matter?
(b) How can the distributions of the kinematics, ages and abundances of halo stars be used to infer the formation history and structure of the stellar halo(s) and Galactic disk(s)?
(c) What does the satellite system of the Milky Way tell us about the extreme edge of galaxy formation?
(d) How have the evolution of the bulge, bar, disk and halo of our Galaxy altered their individual properties and the relationship between them, and how can our understanding of their co-evolution inform our understanding of the formation and evolution of galaxies from high redshifts to today? A significant goal of this workshop is to identify the modeling and simulation tools that need to be developed to construct dynamical and stellar population models of our Galaxy and its various components from the enormous datasets that will soon be available from surveys such as APOGEE, LAMOST, Hermes, Gaia and LSST.

August 4 - August 25
Optical Lattice Emulators and Beyond
Nigel Cooper, University of Cambridge
Tilman Esslinger, Swiss Federal Institute of Technology
Jason Ho*, Ohio State University
Matthias Troyer, ETH Zurich

The development of optical lattice emulators is among the most ambitious projects ever conducted in atomic physics research. The goal is to use cold atoms in optical lattices to simulate important lattice models in condensed matter physics whose solutions remain unknown so far. In the last few years, there have many significant advances in this effort including "quantum simulations" of the bosonic and fermionic Hubbard models and imaging of atoms in optical lattices. The recent success in producing synthetic gauge fields heralds a new generation of cold atom experiments to study spin-orbit effects for bosons and fermions including all those in solids. In addition, recent successes in cooling rare earth atoms and dipolar molecules to quantum degeneracy provide new classes of systems with extraordinary high symmetry (like SU(N)) systems, as well as with long range interaction. Theoretical studies of cold atoms in optical lattices have also continued to blossom in the last few years. There is an increasing number of studies of new phases in optical lattices. At the same time, numerical techniques have risen to a new height to tackle many optical lattice problems. This flurry of excitement in both theory and experiment is a reflection of the great ambitions of the field: to realize the most novel systems in condensed matter and to create new forms of quantum matter difficult to achieve in solids; to explore new mechanisms for strong interaction and strong correlation (hence superfluids with high Tc/TF) ratio; to realize and to manipulate topologically protected excitations; to manufacture, and to find applications of highly entangled quantum states. This workshop aims to bring together theoreticians and experimentalists to push forward the frontier of this exciting field.

August 11 - September 1
Implications of LHC Higgs-Like Signals
John Gunion, University of California, Davis
Howard Haber, University of California, Santa Cruz
Andrey Korytov, University of Florida
Laura Reina*, Florida State University

In July 2012, the ATLAS and CMS collaborations announced the discovery of a new boson with properties suggestive of the Higgs boson of the Standard Model (SM). Since then, additional LHC running has increased the integrated luminosity by nearly a factor of three. With this substantially larger Higgs data sample, the new analyses of the ATLAS and CMS collaborations are beginning to provide a comprehensive picture of the production and decay properties of the 125 GeV Higgs-like state in a variety of channels.

Using this data, one will be able to start to differentiate among models of electroweak symmetry breaking. The Higgs signal could converge towards the SM expectations in all production and decay channels or exhibit significant deviations. In the atter case, models that incorporate new physics beyond the SM (BSM) will be examined for consistency with the data. The Higgs signal has profound implications for supersymmetric models, Randall-Sundrum models (with Higgs-radion mixing), technicolor models, little Higgs models, composite Higgs models, non-minimal Higgs sectors and so on. If there are still no direct signals of new BSM physics at the LHC, then the Higgs data and its interpretation will dominate theoretical model building for years to come. Of course, if the LHC discovers additional new particles and interactions beyond the SM, these discoveries combined with the precision measurements of Higgs properties will significantly constrain models of BSM physics.

The purpose of this workshop is to summarize the experimental situation as of the summer of 2013 and to explore the implications of the Higgs data for the SM and for models containing one or more Higgs-like scalar particles. A key ingredient of the Higgs studies will be the improvement of the accuracy of the theoretical predictions that are crucial for the extraction of the Higgs boson properties from the data.

August 18 - September 15
Dark Matter in Galaxies, the LHC and Direct and Indirect Searches: Are We Near the End of the Road?
Marcela Carena, Fermi National Laboratory
Carlos Frenk, Durham University
Graciela Gelmini*, University of California, Los Angeles
Jennifer Siegal-Gaskins, Caltech

Identifying the nature of the dark matter (DM) is one of the most fascinating and important problems in contemporary physics, and one whose solution may well be within reach. The LHC is exploring many models of new physics that could explain the DM, as well as the direct production of DM. Direct DM searches have provided us with plenty of excitement related to ’Light WIMPs,‘ and this issue will see further developments soon. Tantalizing hints of DM signals have also appeared in indirect searches, such as a 130 GeV line in Fermi LAT data and the rise in the cosmic-ray positron fraction measured by PAMELA and Fermi LAT. Moreover, gamma-ray limits are, for the first time, excluding regions of parameter space for canonical thermal relic WIMP DM. Recent kinematical data for the dwarf galaxy satellites of the Milky Way combined with rigorous predictions of the properties of these systems done with a new generation of ultra-high-resolution N-body simulations, have lead to conflicting evidence: some studies imply that not all is well with the standard Lambda-CDM model and that warm, rather than cold, DM provides a better match to the dwarf satellite data, others, however, suggest that baryon effects can change the picture in subtle but important ways.

This workshop will bring together particle physicists and cosmologists specializing in the issues most relevant for DM detection, including the DM distribution in galaxies as well as all current collider, direct, and indirect searches for particle DM, to explore the complementarity of DM search strategies and re-evaluate the observational evidence for and against a variety of proposed DM candidates.

August 25 - September 15
Multi-Component Many-Body Systems
Egor Babaev*, University of Massachusetts
Leo Radzihovsky, University of Colorado
James Sauls, Northwestern University
Asle Sudbo, Norwegian University of Science and Technology

Research on the multicomponent systems has increased enormously in recent years due to a number of experimental breakthroughs. These include unconventional and multiband superconductors, topological superfluids and superconductors, spinor Bose-Einstein condensates, quantum mixtures of fermionic and bosonic cold atoms, quantum magnets and spin-liquids, and quantum Hall systems, and various multicomponent gauge theories emerging as effective theories in various physical context. Multicomponent ordered states often exhibit properties which have no counterpart in single-component systems. Despite a diverse range of microscopic origins, at low energies this broad array of systems can often be described by emergent many-body theories exhibiting a significant degree of universality. There are for instance important connections between topological insulators, quantum Hall physics and the phases of superfluid 3He as well multi-component cold atomic condensates. This workshop will provide a forum for many-body experts in a broad range of areas to interact and exchange ideas on such diverse multi-component systems.

September 1 - September 15
Astrophysical Mechanisms of Particle Acceleration and Escape from the Accelerators
Mikhail Malkov*, University of California, San Diego
Patrick Diamond, University of California, San Diego
Roald Sagdeev, University of Maryland

Recent progress in observations brings high energy astrophysics to the forefront of particle physics experiments studying fundamental laws. Cosmic rays (CR), with an energy spectrum extended to 100 EeV, are unique messengers with which to probe the structure and evolution of the universe, dark matter, neutrinos, and other important phenomena in astroparticle physics and cosmology, possibly including particles that are yet to be discovered. The newest discovery of the GZK feature at 30 EeV in the CR spectrum bolsters our basic understanding of how the universe works at extreme energies but the observations also pose new questions about the composition and anisotropy of the spectrum. The workshop will encompass CR acceleration mechanisms in various astrophysical settings and discuss their radiative and morphological signatures. For more than thirty-five years the diffusive shock acceleration (DSA, aka Fermi-I) mechanism has been successfully applied to CR production in supernova remnants, gamma ray bursts, active galactic nuclei, and even in the cosmic structure formation shocks. However, its role in other important phenomena such as magnetic field generation, particle escape from accelerators, their subsequent propagation and interaction with ambient medium are not fully understood. It is this interaction that results in the emission that it is now measured with unprecedented precision. These measurements are not always explicable within the standard DSA theory. Therefore, alternative mechanisms, powered by magnetic and turbulence energy, rather than by the mechanical shock energy, will also be discussed.