2025 Simons Collaboration on Confinement and QCD Strings Annual Meeting

Igor Klebanov
Princeton University

Collaboration Overview

Igor Klebanov will review some of the key research accomplishments made by collaboration members so far and describe our plans. They will include continuation of the current projects and addition of new research topics.
 

Ofer Aharony
Weizmann Institute of Science

How Does Confinement Begin? On the Possible End-Points of Conformal Windows

The generalization of QCD to arbitrary numbers of colors \(N_c\) and of massless flavors \(N_f\) has a “conformal window” of values of \(N_f\) where the theory flows to a non-trivial conformal field theory with no confinement, such that, as the number of flavors is decreased, the theory transitions to a confining phase (with chiral symmetry breaking). This transition becomes continuous in the limit of large \(N_f\) and \(N_c\) with a fixed ratio between them, and similar continuous transitions ending “conformal windows” occur also in many other theories.

In this talk, which is a continuation of his talk at last year’s collaboration meeting, Ofer Aharony will describe four general ways (one of which is the popular “merger scenario”) for how such “conformal windows” can end, and present examples where each of them occurs. It is not known which of these scenarios occurs in (large \(N_c\)) QCD, and Aharony will describe how they can be distinguished by precise lattice simulations.
 

Michele Caselle
Torino University

Advanced Simulation Methods for Lattice Gauge Theories and New Results in (2+1) Dimensions

In this talk, Michele Caselle will first discuss a recent proposal to improve the effectiveness of lattice gauge theories (LGTs) simulations by combining non-equilibrium Monte Carlo sampling with machine-learning flows in the so-called stochastic normalizing flows (SNF) algorithm.

In the second part of the talk, Caselle will present a few results we obtained over the past year on the effective string approach to (2+1) dimensional LGTs. In particular, he will present estimates for the mass of the Baryon junction, the behavior of the effective string potential in the U(1) theory and on the intrinsic width of the flux tube in the SU(2) LGT.
 

Silviu Pufu
Princeton University

Precision Studies and Supersymmetry of 2D Adjoint QCD and Its Generalizations

The 1+1-dimensional adjoint QCD theory — namely, SU(N) gauge theory coupled to a Majorana fermion in the adjoint representation of the gauge group — has been a useful model for understanding a variety of gauge theory phenomena in a more tractable setup.

In this talk, Silviu Pufu will describe some recent progress on numerical simulations of this theory involving infinite tensor networks. Afterwards, he will focus on a specific value of the fermion mass where the adjoint QCD theory exhibits supersymmetry. He will describe the construction of a gauge-invariant, Lorentz-covariant supercurrent, whose conservation relies on the presence of a quantum anomaly. Lastly, he will discuss generalizations of the 2D adjoint QCD theory that exhibit supersymmetric sectors.
 

Ian Moult
Yale University

Unveiling QCD Dynamics with Energy Correlators

Enter AbstraDetector operators, of which the average null energy operator provides the most famous example, arise as direct theoretical models of asymptotic measurements in collider experiments. It has recently become possible to directly measure correlation functions of these detector operators with extreme precision, unveiling the non-integer scaling behavior of quarks and gluons, the dynamics of QCD flux tubes, and the confinement transition.

In this talk, Ian Moult will present an overview of recent theoretical and experimental studies of these correlators, highlighting in particular their application for understanding confinement in QCD.
 

Mithat Ünsal
North Carolina State University

Self-Dual Monopole Loops, Instantons and Confinement

It is well-known that the standard instanton analysis in 4D Yang-Mills theory is plagued with the instanton size moduli problem, which renders the instanton contribution to vacuum energy density (or the one-instanton partition function) infrared divergent. The formalism also ignores the implications of the long-range (magnetic dipole type) \(1/r^4\) interaction between the small instantons, since it is weaker than a Coulomb interaction. We show that, in the \(U(1)\) lattice gauge theory, where finite action configurations are monopole loops, small loops at large separations also interact with the same type of \(1/r^4\) interaction. If one ignores the classical interactions between monopoles, following the same idea as in Yang-Mills theory, the one-monopole partition function is also infrared divergent at strong coupling. However, the \(1/r^4\) interactions among small loops should be viewed due to the multipole expansion, and they emanate from the \(1/r^2\) interaction between current segments. Taking interactions into account, one can prove that the strongly coupled \(U(1)\) lattice gauge theory is dual to a lattice abelian Higgs model, and more importantly, free of infrared divergences. The model exhibits mass gap and confinement by monopole condensation. We suggest that the structure of moduli space of instantons, ADHM data, and the long-ranged classical interactions in pure Yang-Mills theory should be examined with this refined perspective. We conjecture that, in contradistinction to the current views on the subject, internal structure of instantons in Yang-Mills theory is responsible for confinement in 4D gauge theory, similarly to the 2D sigma model.
 

Phiala Shanahan
Massachusetts Institute of Technology

Hadrons, Nuclei, and Glueballs from Lattice QCD

Phiala Shanahan will describe recent calculations that give insight into different confined states in QCD, including glueballs, hadrons, and nuclei. Shanahan will also discuss how algorithmic advances are overcoming computational limitations and progressing the state-of-the-art in this area.
 

Sergei Dubovsky
New York University

Worldsheet Axion: The Status Report
Sergei Dubovsky will review what we learned over the past few years about the properties of the only known massive excitation of the confining string — the worldsheet axion. Its properties can be studied purely theoretically, and also using lattice results and also from the real world hadron spectroscopy. After reviewing the known properties, Dubovsky will highlight the emerging puzzles and challenges which will hopefully be resolved in the near future.

Participation in the meeting falls into the following four categories. An individual’s participation category is communicated via their letter of invitation.

The Simons Foundation will never ask for credit card information or require payment for registration to our events.

Group A – Speakers & Organizers

Individuals in Group A receive travel and hotel coordination within the following parameters:

Travel
Economy Class: For flights that are three hours or less to your destination, the maximum allowable class of service is Economy class.
Premium Economy Class: For flights where the total air travel time (excluding connection time) is more than three hours and less than seven hours per segment to your destination, the maximum allowable class of service is premium economy.
Business Class: When traveling internationally (or to Hawaii/Alaska) travelers are permitted to travel in Business Class on those segments that are seven hours or more. If the routing is over budget, a premium economy or mixed-class ticket will be booked.

Hotel
Up to 3 nights at the conference hotel, arriving on Wednesday, November 13 and departing on Saturday, November 15.

Group B – Funded Participants

Individuals in Group B receive travel and hotel coordination within the following parameters:

Travel
Economy class travel will be booked regardless of flight length.

Hotel
Up to 3 nights at the conference hotel, arriving on Wednesday, November 13 and departing on Saturday, November 15.

Group C – Unfunded Participants

Individuals in Group C will not receive financial support but are encouraged to enjoy all conference-hosted meals.

Group D – Remote Participants

Individuals in Group D will participate in the meeting remotely.

Air and Rail

For funded individuals, the foundation will arrange and pay for round-trip travel from their home city to the conference city. All travel and hotel arrangements must be booked through the Simons Foundation’s preferred travel agency.

Travel Deviations

The following travel specifications are considered deviations and will only be accommodated if the cost is less than or equal to the amount the Simons Foundation would pay for a standard round-trip ticket from your home city to the conference city:

• Preferred airline
• Preferred travel class
• Specific flights/flight times
• Travel dates outside those associated with the conference
• Arriving or departing from an airport other than your home city or conference city airports, i.e. multi-segment or triangle trips.

All deviations must be reviewed and approved by the Simons Foundation and, if the cost is more than what would normally be paid, a reimbursement quote must be obtained through the foundation’s travel agency before proceeding to booking and paying for travel out of pocket. All reimbursements for travel booked directly will be paid after the conclusion of the meeting.

Changes After Ticketing

All costs related to changes made to ticketed travel are to be paid for by the participant and are not reimbursable. Please contact the foundation’s travel agency for further assistance.

Personal & Rental Cars

Personal car and rental trips over 250 miles each way require prior approval from the Simons Foundation via email.

Rental cars must be pre-approved by the Simons Foundation.

The Hotel Seville NoMad offers valet parking. Please note there are no in-and-out privileges when using the hotel’s garage, therefore it is encouraged that participants walk or take public transportation to the Simons Foundation.

Hotel

Funded individuals who require hotel accommodations are hosted by the foundation for a maximum of 3 nights at the conference hotel, arriving on Wednesday, November 13 and departing on Saturday, November 15.

Any additional nights are at the attendee’s own expense. To arrange accommodations, please register at the link included in your invitation.

Hotel Seville NoMad
22 E 29th St
New York, NY 10016
(between 28th and 29th Streets)
https://www.hyatt.com/unbound-collection/en-US/nycud-hotel-seville-nomad

For driving directions to the Hotel Seville NoMad, please click here.

Overview

In-person participants will be reimbursed for meals and local expenses including ground transportation. Expenses should be submitted through the foundation’s online expense reimbursement platform after the meeting’s conclusion.

Expenses accrued because of meetings not directly related to the Simons Foundation-hosted meeting (a satellite meeting or meeting held at another institution, for example) will not be reimbursed by the Simons Foundation and should be paid by other sources.

Below are key reimbursement takeaways; a full policy will be provided with the final logistics email circulated approximately 2 weeks prior to the meeting’s start.

Meals

The daily meal limit is $125; itemized receipts are required for expenses over $24 USD. The foundation DOES NOT provide a meal per diem and only reimburses actual meal expenses up the following amounts.

• Breakfast $20
• Lunch $30
• Dinner $75

Allowable Meal Expenses

• Meals taken on travel days (when you traveled by air or train).
• Meals not provided on a meeting day, dinner on Friday for example.
• Group dinners consisting of fellow meeting participants paid by a single person will be reimbursed up to $75 per person and the amount will count towards the $125 daily meal limit.

Unallowable Meal Expenses

• Meals taken outside those provided by the foundation (breakfast, lunch, breaks and/or dinner).
• Meals taken on days not associated with Simons Foundation-coordinated events.
• Minibar expenses.
• Meal expenses for a non-foundation guest.

• Ubers, Lyfts, taxis, etc., taken to and from restaurants in Manhattan.

  • Accommodations will be made for those with mobility restrictions.

Ground Transportation

Expenses for ground transportation will be reimbursed for travel days (i.e. traveling to/from the airport or train station) as well as subway and bus fares while in Manhattan are reimbursable.

Transportation to/from satellite meetings are not reimbursable.

Attendance

In-person participants and speakers are expected to attend all meeting days. Participants receiving hotel and travel support wishing to arrive on meeting days which conclude at 2:00 PM will be asked to attend remotely.

Entry & Building Access

Upon arrival, guests will be required to show their photo ID to enter the Simons Foundation and Flatiron Institute buildings. After checking-in at the meeting reception desk, guests will be able to show their meeting name badge to re-enter the building. If you forget your name badge, you will need to provide your photo ID.

The Simons Foundation and Flatiron Institute buildings are not considered “open campuses” and meeting participants will only have access to the spaces in which the meeting will take place. All other areas are off limits without prior approval.

If you require a private space to conduct a phone call or remote meeting, please contact your meeting manager at least 48-hours ahead of time so that they may book a space for you within the foundation’s room reservation system.

Guests & Children

Meeting participants are required to give 24-hour advance notice of any guests meeting them at the Simons Foundation either before or after the meeting. Outside guests are discouraged from joining meeting activities, including meals.

With the exception of Simons Foundation and Flatiron Institute staff, ad hoc meeting participants who did not receive a meeting invitation directly from the Simons Foundation are not permitted.

Children under the age of 18 are not permitted to attend meetings at the Simons Foundation. Furthermore, the Simons Foundation does not provide childcare facilities or support of any kind. Special accommodations will be made for nursing parents.

Meeting & Policy Questions

Meghan Fazzi
Senior Manager, Events & Administration
[email protected]

Travel & Hotel Support

FCM Travel Meetings & Events
[email protected]
Hours: M-F, 8:30 AM-5:00 PM ET
+1-888-789-6639