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Topological avatars of new physics

Discussion meeting

Location

The Royal Society, London, 6-9 Carlton House Terrace, London, SW1Y 5AG

Overview

Scientific Discussion meeting organised by Professor Nikolaos Mavromatos, Dr Laura Patrizii, Dr Vasiliki Mitsou, Professor James Pinfold, Dr Adrian Bevan, Professor Arttu Rajantie and Professor Jonathan Ellis CBE FRS.

An artist's impression of a topological avatar of new physics in the Higgs field. Image courtesy of Professor James Pinfold

The meeting will discuss the theoretical and experimental status of searches for topologically non-trivial solutions in quantum field theories of particle physics, including the Standard Model and its extensions. It will cover both current and future colliders and cosmic searches both on Earth and in space. The topics will include black holes, magnetic monopoles, sphalerons, Q-balls and other solitonic solutions.

The schedule of talks and speaker biographies is available below. Recorded audio of the presentations will be available on this page after the meeting has taken place.

Poster session

There will be a poster session at 17:15 on Monday 4 March. If you would like to apply to present a poster please submit your proposed title, abstract (not more than 200 words and in third person), author list, name of the proposed presenter and institution to the Scientific Programmes team no later than Monday 28 January 2019. Please note that places are limited and posters are selected at the scientific organisers' discretion. Poster abstracts will only be considered if the presenter is registered to attend the meeting.

Attending the event

This meeting is intended for researchers in relevant fields. 

  • Free to attend
  • Limited places, advanced registration is essential
  • An optional lunch can be purchased during registration
  • An evening poster session and drinks reception will be held following the close of the meeting on Monday 4 March 2019. Whilst the posters are free to view for all registered participants, the corresponding optional drinks reception is ticketed. Drinks reception tickets can be purchased in advance during registration

Enquiries: Contact the Scientific Programmes team.

Event organisers

Select an organiser for more information

Schedule of talks

04 March

09:00-12:30

Session 1

5 talks Show detail Hide detail

Chairs

Professor Nick Mavromatos, King's College London, UK

09:00-09:20 Welcome by the Royal Society & Professor Nick Mavromatos

09:20-09:50 Quantum black holes without chaos

Professor Gerard 't Hooft, Institute for Theoretical Physics, Netherlands

Abstract

The effects of quantum mechanics on the laws of the gravitational force are difficult to formulate. In the absence of direct experimental information, one must rely on all available knowledge concerning quantum mechanics as well as diffeomorphism invariance, and analyze the questions that arise, as accurately as possible, without using arbitrary assumptions. A most important testing ground is the subject of microscopic black holes. The predictions by standard General Relativity are clear: tiny black holes can grow and shrink by absorbing and emitting particles. Quantum mechanics predicts an evolution law described by a unitary operator. All that is needed here is an operator for tiny or infinitesimal time steps, and this evolution law should be in accordance with the physical laws describing domains of space-time near the horizon. In the lecture, it is claimed that solutions proposed in the literature are wanting in this respect. In particular, these assume that black hole particle emission must be “chaotic”, while it is unreasonable to expect chaos to form during short time stretches. One can do better. The evolution operator is found to be unitary and obey some basic principles of locality. A necessary modification of accepted rules is the so‐called antipodal identification. Another is the identification of Hawking particles emitted by the hole, with the gravitational footprints of all in‐going particles. These observations are used to obtain theories for quantum gravity even in flat backgrounds, in ways often not considered.

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10:00-10:30 The electroweak monopole: the theory behind it, properties and its relevance in cosmology

Professor Yongmin Cho, Sogang University, Korea

Abstract

The electroweak monopole in the standard model, the existence, characteristic features, cosmological production, and physical implications are discussed. The discovery of Higgs particle has been thought to be the 'final' test of the standard model. If the standard model is correct, however, it must have the electroweak monopole as the electroweak generalization of the Dirac monopole. This means that the detection of this monopole should become the final and topological test of the standard model. If detected, it becomes the first magnetically charged and stable topological elementary particle in the history of physics. Moreover, it has deep implications in physics. In cosmology it could generate the primordial magnetic black holes which could explain the dark matter, become the seed of the large scale structures of the universe, and be the source of the intergalactic magnetic field. As importantly, it could generate the hitherto unknown magnetic current that could have huge practical applications. Furthermore the existence of the monopole requires us to reformulate the perturbative expansion in quantum field theory. This makes the detection of the electroweak monopole a most urgent issue. Useful tips for the MoEDAL detector at LHC and similar experiments to detect the monopole are discussed.

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10:40-11:10 Coffee

11:10-11:40 Monopole-antimonopole: interactions, scattering and creation

Professor Tanmay Vachaspati, Arizona State University, USA

Abstract

The interaction of a magnetic monopole-antimonopole pair depends on their separation as well as on a second "twist'" degree of freedom. This novel interaction leads to a non-trivial bound state solution known as a sphaleron and to scattering in which the monopole-antimonopole bounce off each other and do not annihilate. The twist degree of freedom also plays a role in numerical experiments in which gauge waves collide and create monopole-antimonopole pairs. Similar gauge wavepacket scatterings in the Abelian-Higgs model lead to the production of string loops that may be relevant to superconductors. Ongoing numerical experiments to study the production of electroweak sphalerons that result in changes in the Chern-Simons number, and hence baryon number, are also described but have not yet met with success.

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11:50-12:20 Cosmological evolution of semilocal networks

Professor Ana Achúcarro, Professor Ana Achúcarro, Leiden University, Netherlands and University of the Basque Country, Spain

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12:30-13:30

Lunch

13:30-17:00

Session 2

6 talks Show detail Hide detail

Chairs

Professor Veronica Sanz, University of Sussex, UK

13:30-13:55 Machine learning techniques for detecting topological avatars of new physics

Dr Adrian Bevan, Queen Mary University of London, UK

Abstract

The search for highly ionising particles in nuclear track detectors (NTDs) traditionally requires experts to manually search through samples in order to identify regions of interest that could be a hint of physics beyond the Standard Model (SM). The advent of automated image acquisition and modern data science, including machine learning-based processing of data, presents an interesting opportunity to accelerate the process of searching for anomalies in NTDs that could be a hint of a new physics avatar. 

The potential for modern data science to be applied to this topic is discussed, in the context of the MoEDAL experiment at the Large Hadron Collider (LHC) at the European Centre for Nuclear Research, CERN. Polymer chains in the NTDs are damaged by ionising particles traversing the plastic. Subsequent chemical etching of the plastic results in nanoscopic damage being transformed into microscopic damage – visible under a microscope or on a modern scanner system. Featuring finding algorithms can be developed, ranging from traditional clustering algorithms to modern deep-learning methods, in order to address the issue of identifying holes in the plastic. A heavily ionising avatar will differ from a SM particle as it will traverse a stack of NTDs inflicting damage to many adjacent foils, whereas the SM particle will range out only affecting a few foils as that particle comes to rest. The potential for modern data science to be applied to this area is explored.

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14:05-14:35 The inevitability of sphalerons in field theory

Professor Nicholas Manton FRS, University of Cambridge, UK

Abstract

Many field theories have nonlinear equations, but more interesting is when the nonlinearity is geometrically essential, and independent of the details of the theory. This can happen through constraints on the fields, as in sigma models, through the geometry of the vacuum manifold, or through the need to quotient out by gauge transformations. When the Higgs mechanism operates, a nontrivial vacuum manifold and gauge transformations combine. In many such field theories, the field potential energy function inevitably has saddle-points in the infinite-dimensional field configuration space, and these are sphalerons. Sphalerons are smooth, spatially localised solutions of the static field equations, so they are rather like solitons, but unlike solitons they are unstable [ancient Greek: sphaleros = unstable]. Examples of sphalerons are kink-antikink and monopole-antimonopole solutions. Also, the electroweak sector of the Standard Model has no monopoles, but it has sphaleron solutions. The Skyrme model of baryons and nuclei has stable solitons, and also higher energy sphaleron-type solutions. Sphalerons can set the energy scale where perturbation theory breaks down, and control the energy scale for tunnelling, analogous to the transition state controlling a chemical reaction. Tunnelling processes in electroweak theory are accompanied by violations of baryon and lepton number, and could have been important in the early universe.

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14:45-15:15 Tea

15:15-15:40 Searches for cosmic magnetic monopoles: past, present and future

Dr Laura Patrizii, Istituto Nazionale di Fisica Nucleare, Italy

Abstract

In 1931 Dirac introduced the magnetic monopole in order to explain the quantization of the electric charge. Grand Unification Theories (GUT) of the basic interactions imply the existence of monopoles of extremely large mass, O(1016 GeV/c2 ). Larger masses are expected if gravity is brought into the unification picture. Intermediate mass magnetic monopoles (105 – 1012  GeV/c2) are predicted by theories with an intermediate energy scale between the GUT and the electroweak scales and would appear in the early universe at a considerably later time than the GUT epoch. The lowest mass magnetic monopoles should be stable, therefore they should still exist as cosmic relics from the early universe and be a component of the cold dark matter.

Significant efforts have been made over several decades searching for magnetic monopoles whose discovery would represent a breakthrough in particle physics, astrophysics and cosmology. Supermassive poles should have low velocities and relatively large energy losses; they are best searched for underground in the penetrating cosmic radiation. Lower mass monopoles could be relativistic reaching high altitude laboratories.

In this talk the status of the searches for classical, super-heavy, and intermediate mass monopoles with experiments in space, at high altitudes, underground and underwater/ice is reviewed, emphasizing the most recent results and future perspectives.

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15:50-16:15 Monopole-antimonopole pair production by magnetic fields

Professor Arttu Rajantie, Imperial College London, UK

Abstract

It is a well-known prediction of quantum electrodynamics that in a strong electric field, electron-positron pairs are produced through the Schwinger process, which can be interpreted as quantum tunnelling through the Coulomb potential barrier. If magnetic monopoles exist, the monopole-antimonopole pairs would be produced by strong magnetic fields through the electromagnetic dual of this process. The production rate can be computed using semiclassical techniques without relying on perturbation theory, and therefore it can be done reliably in spite of monopoles’ strong coupling to the electromagnetic field. This talk explains this process and discusses the bounds on monopole masses arising from the strongest magnetic fields in the universe, which are in neutron stars known as magnetars and in heavy ion collision experiments such as lead-lead collisions carried out in November 2018 in Large Hadron Collider at CERN. The talk will also discuss open theoretical questions affecting the calculation.

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16:25-16:50 The MoEDAL experiment at the LHC - a new light on the high energy frontier

Professor James Pinfold, University of Alberta, Canada

Abstract

MoEDAL is a pioneering LHC experiment designed to search for anomalously ionizing messengers of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles, which are predicted to existing in a plethora of models beyond the Standard Model. It started data taking at the LHC at a centre-of-mass energy of 13 TeV in 2015. Its ground breaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as: are there extra dimensions or new symmetries; what is the mechanism for the generation of mass; does magnetic charge exist; and what is the nature of dark matter. MoEDAL's purpose is to meet such far-reaching challenges at the frontier of the field. We will present the results from the MoEDAL detector on Magnetic Monopole and highly ionizing electrically charged particle production that are the world’s best. In conclusion, progress on the installation of MoEDAL’s MAPP (MoEDAL Apparatus for the detection of Penetrating Particles) sub-detector prototype will be very briefly be discussed.

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17:15-18:15 Poster Session

05 March

09:00-12:35

Session 3

5 talks Show detail Hide detail

Chairs

Professor Vasiliki Mitsou, IFIC, CSIC - University of Valencia, Spain

09:00-09:30 Prospects for High Energy Physics, including searches for highly ionising particles in current and future colliders

Professor Albert De Roeck, CERN, Switzerland

Abstract

This contribution will discuss briefly the status of present searches for new particles at the high energy frontier, as conducted at the LHC. It will then introduce ideas of potentially new experiments to search for long lived highly ionising topological avatars, as well as so called hidden particles. The discovery of such new particles would lead to major advancements and the deeper understanding of particle physics beyond the Standard Model, and directly address present open questions such as dark matter, the matter asymmetry in the universe and others. New experiments for long lived particles at the LHC comprise the MilliQan, the Codex-b, the MATHUSLA, the FASER and the AL3X experiments. Some of these experimental ideas are also explored for planning future beam-dump experiments e.g. at neutrino experiment near detectors and for the proposal of the CERN/SHiP experiment. The potential for searches for such particles at future new colliders is also briefly discussed.

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09:40-10:10 Monopoles in the standard model

Professor David Tong, University of Cambridge, UK

Abstract

Two things will be explained in this talk. First, that there is an ambiguity in the gauge group of the Standard Model, and this affects the possible monopoles that may be observed in the future. Second, that there is an unsolved problem in how to define magnetically charged particles in gauge theories with chiral matter.

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10:20-10:45 Coffee

10:45-11:15 Baryon number violating scatterings in the laboratory

Professor S H Henry Tye, Cornell University, USA

Abstract

Although it is well known that baryon number violating processes happen in the electroweak theory, there is a large (about 70 orders of magnitude) discrepancy in the determination of the baryon number violating scattering cross-sections at energies around the sphaleron energy of 9 TeV, separating the potentially observable from the totally unobservable predictions in the laboratory.

The (old) pessimistic estimate is unreliable as the energy approaches the sphaleron energy, so it is useful to take an entirely different approach to this problem. The more optimistic estimate is based on the Bloch wave approach, which reliably covers energies ranging from zero to the sphaleron energy and above. At low energies, both studies yield an exponentially small cross-section, but the Bloch wave approach yields a much bigger rate as the energy approaches the sphaleron energy. Recently, this idealized Bloch wave approach is further improved by taking into account the presence of the baryon number conserving direction as well as the fermion masses, a much more realistic situation.

At the present proton-proton energy of 14 TeV at the LHC, the parton distribution and phase space suppression is quite severe. Orders of magnitude in the event rate can be gained if LHC can double its present energy.

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11:25-11:55 Baryon number violating processes in particle collisions at very high energies

Professor Sergei Demidov, Institute for Nuclear Research of Russian Academy of Sciences, Russia

Abstract

Conservation of baryon number is one of the fundamental laws which has been verified with a great accuracy. However, existence of baryon number violating processes is predicted within the Standard Model of particle physics. These processes are related to the transitions between topologically nonequivalent vacua which are separated by a potential barrier. The probability of these processes is known to be exponentially suppressed at small energies but grows with the energy increase. This talk discusses a semiclassical method to calculate the probability of the baryon number violating processes induced by collisions of a few particles. The method is argued to be valid at all collision energies and improved numerical calculations confirm that the probability of baryon number violating processes stay exponentially suppressed even at the energies much larger than the barrier height. Possible applications to extensions of the Standard Model are discussed.

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12:00-12:25 Searching for supersymmetry

Professor John Ellis CBE FRS, King’s College London, UK

Abstract

Supersymmetry is one of the most interesting scenarios for physics beyond the Standard Model. It could help us understand the scale of the weak interactions and the mass of the Higgs boson, it would help unify the fundamental interactions, and it could provide the dark matter expected by astrophysicists and cosmologists. Supersymmetry predicts the existence of many new particles. None has yet been discovered, but it is possible that there might exist a long-lived supersymmetric particle that could be detected by the MoEDAL experiment at the Large Hadron Collider.

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12:35-13:35

Lunch

13:35-17:00

Session 4

4 talks Show detail Hide detail

Chairs

Professor Mairi Sakellariadou, King's College London, UK

13:35-14:05 Black holes in the quantum universe

Professor Steven Giddings, University of California, Santa Barbara and CERN, USA

Abstract

In general relativity, black holes furnish classic examples of spacetime topology - as well as predicting its breakdown. But nature is quantum-mechanical, and this appears to force a different view of black holes and of spacetime itself. This talk will sketch some basic elements of proposals for this structure and for black hole evolution that is consistent with quantum mechanics.

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14:15-14:45 Primordial black holes as dark matter and their detection with gravitational waves

Professor Juan Garcia-Bellido, Universidad Autonoma de Madrid, Spain

Abstract

More than twenty-two years ago, we predicted that massive primordial black holes (PBH) would form via the gravitational collapse of radiation and matter associated with high peaks in the spectrum of curvature fluctuations, and that they could constitute all of the dark matter today. In 2015, we predicted the clustering and broad mass distribution of PBH, which peaks at several Msun, and whose high-mass tails could be responsible for the seeds of all galaxies. Since then, LIGO has detected gravitational waves from ten merger events of very massive black hole binaries. We propose that they are PBH, and predict that within a few years a less than one solar mass PBH will be detected by AdvLIGO-VIRGO, and that in 10 years, an array of GW detectors (i.e. LIGO, VIRGO, KAGRA, INDIGO, etc.) could be used to determine the mass and spin distribution of PBH dark matter with 10% accuracy. Thus, gravitational wave astronomy could be responsible for a new paradigm shift in the understanding of the nature of dark matter and the evolution of the large scale structures in the universe.

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14:55-15:20 Tea

15:20-15:50 Black hole dark matter

Professor Marc Kamionkowski, Johns Hopkins University, USA

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16:00-17:00 Panel discussion/overview

Professor Annarita Margiotta, University of Bologna, Italy
Professor John Ellis CBE FRS, King’s College London, UK
Professor Albert De Roeck, CERN, Switzerland
Professor Steven Giddings, University of California, Santa Barbara and CERN, USA
Professor Marc Kamionkowski, Johns Hopkins University, USA
Professor Vasiliki Mitsou, IFIC, CSIC - University of Valencia, Spain
Professor James Pinfold, University of Alberta, Canada
Professor Mairi Sakellariadou, King's College London, UK
Professor Veronica Sanz, University of Sussex, UK
Professor Tanmay Vachaspati, Arizona State University, USA

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Topological avatars of new physics

4 - 5 March 2019

The Royal Society, London 6-9 Carlton House Terrace London SW1Y 5AG UK
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