Particle Physics

Particle physics is the science which identifies nature's constituents and interactions at the most fundamental level, with an emphasis on comparing theoretical ideas with both terrestrial experiments and astrophysical observations. This mandate gives it a strong overlap with string theory, quantum gravity and cosmology. Particle physicists at Perimeter Institute are currently involved in identifying how cosmological observations and terrestrial accelerator and underground experiments constrain the theoretical possibilities for physics beyond the Standard Model.

Displaying 709 - 720 of 1410

Spin and Long-Range Forces: The Unfinished Tale of the Last Massless Particle

Natalia Toro
Stanford University
November 13, 2013

PIRSA:13110047
Particle Physics
Baryogenesis from WIMPs
November 12, 2013

PIRSA:13110046
Particle Physics
Induced Electroweak Symmetry Breaking and Supersymmetry

Jamison Galloway
New York University (NYU)
November 05, 2013

PIRSA:13110050
Particle Physics
Split Dirac Supersymmetry and a Higgsino LSP
November 01, 2013

PIRSA:13110052
Particle Physics
Gravity and the Search for New Physics with Cosmology

Kris Sigurdson
University of British Columbia
October 30, 2013

PIRSA:13100098
Particle Physics
Minimal Distances and the RG Flow
October 29, 2013

PIRSA:13100069
Particle Physics
Heavy particle effective field theory: formalism, dark matter and the proton size puzzle

Richard Hill
University of Kentucky
October 18, 2013

PIRSA:13100107
Particle Physics
Including astroparticle observables in global fits to new physics scenarios

Patrick Scott
McGill University
October 15, 2013

PIRSA:13100103
Particle Physics
Electroweak Cogenesis and a CP Violating Higgs Boson
September 24, 2013

PIRSA:13090077
Particle Physics
The Era of Three Generations: Possible hints from neutrinos in elucidating the matter/antimatter asymmetry of the Universe
September 11, 2013

PIRSA:13090065
Particle Physics
The local Callan-Symanzik equation: structure and applications

Boaz Keren-Zur
L'Ecole Polytechnique Federale de Lausanne (EPFL)
September 06, 2013

PIRSA:13090067
Particle Physics
Bottom-up Naturalness

Sonia El Hedri
Stanford University
August 27, 2013

PIRSA:13080056
Particle Physics

Spin and Long-Range Forces: The Unfinished Tale of the Last Massless Particle

Natalia Toro
Stanford University
November 13, 2013

PIRSA:13110047
Particle Physics
The success of gauge theory descriptions of Nature follows simply, in hindsight, from Lorentz symmetry, quantum mechanics, and the existence of interacting massless particles with spin. Yet, remarkably, the most generic type of massless particle spin has never been seriously examined: Wigner's so-called "continuous spin" particles (CSPs), which have a tower of polarization states carrying all integer or half-integer helicities that mix under boosts. I will explain recent progress in understanding these particles on two fronts: simple scattering amplitudes and a free quantum field theory. The scattering amplitudes give two remarkable insights into CSP physics. First, Lorentz symmetry protects CSP interactions from the dysfunction one might expect in a theory with infinitely many polarization states: divergent cross-sections and problematic thermodynamics. Second, and most intriguingly, CSP interactions approach those of ordinary scalars or helicity-1 or 2 gauge bosons in a high-energy "correspondence" regime. While a full interacting theory of CSPs remains elusive, these results suggest that any such theory would extend Maxwell electrodynamics and/or general relativity in a viable and testable way.
Baryogenesis from WIMPs
November 12, 2013

PIRSA:13110046
Particle Physics
We propose a robust, unified framework, in which the similar baryon and dark matter cosmic abundances both arise from the physics of weakly interacting massive particles (WIMPs), with the rough quantitative success of the so-called “WIMP miracle”. In particular the baryon asymmetry arises from the decay of a meta-stable WIMP after its thermal freezeout at or below the weak scale. A minimal model and its embedding in R-parity violating (RPV) natural SUSY are studied as examples. The new mechanism saves RPV SUSY from the potential crisis of washing out primordial baryon asymmetry. We also consider the embedding of this idea in RPV split SUSY, where the mechanism works within the minimal model, and independently motivates the mini-split scale. Phenomenological implications for the LHC and precision tests are discussed.
Induced Electroweak Symmetry Breaking and Supersymmetry

Jamison Galloway
New York University (NYU)
November 05, 2013

PIRSA:13110050
Particle Physics
I'll discuss a class of supersymmetric models in which the physical Higgs mass is freed from the quartic coupling, thereby allowing for a 125 GeV Higgs state whose self-interaction can be much smaller than in the SM via a mechanism of 'induced EWSB'. This class of models provides a unique alternative to other realizations of natural SUSY, and the simplest realizations necessitate additional characteristic scalars below the TeV scale, thus altering phenomenological predictions for additional Higgses at the LHC.
Split Dirac Supersymmetry and a Higgsino LSP
November 01, 2013

PIRSA:13110052
Particle Physics
TBA
Gravity and the Search for New Physics with Cosmology

Kris Sigurdson
University of British Columbia
October 30, 2013

PIRSA:13100098
Particle Physics
Despite its feeble in strength, gravity plays a pivotal role in shaping our Universe and the things in it. Ever since Newton formulated his universal law of gravitation the recognition that all things gravitate has been nearly sacrosanct. Repeatedly, apparent gravitational anomalies have either foretold the existence of new physics or a misunderstanding of gravity itself, from the existence of nuclear forces to Einstein's general relativity. Eighty years ago gravity betrayed the existence of dark matter, and fifteen years ago gravity demanded dark energy from reluctant cosmologists. I will discuss how gravity enables modern cosmology to explore the echoes of the invisible universe, even if it is impossible or difficult to directly see the invisible universe. In particular, I will show how gravity enables us to put surprisingly severe constraints on the coupling of dark matter to new light particles and search for secret interactions between Fermi's elusive neutrinos. The physics and cosmic history of the invisible universe are writ large across the cosmos itself, and gravity is our tried and trusted messenger.
Minimal Distances and the RG Flow
October 29, 2013

PIRSA:13100069
Particle Physics
We will discuss the renormalization group flow between different classes of CFTs in four dimensions and study possible lower bounds on the "distances" between these theories.
Heavy particle effective field theory: formalism, dark matter and the proton size puzzle

Richard Hill
University of Kentucky
October 18, 2013

PIRSA:13100107
Particle Physics
Heavy particle expansions, familiar from heavy quark physics, have found important applications in the analysis of dark matter candidates and their interactions with the Standard Model. From a different direction, precision spectroscopy of muonic hydrogen has challenged QED and required more precise knowledge of proton structure. These problems have forced a closer examination of the construction of general heavy particle lagrangians at high orders in the 1/M expansion, and in the absence of known ultraviolet completions. Key aspects of this formalism, including the emergence of Lorentz invariance from "nonrelativistic" lagrangians, are reviewed, and several applications are presented. A status report on the proton radius puzzle is given.
Including astroparticle observables in global fits to new physics scenarios

Patrick Scott
McGill University
October 15, 2013

PIRSA:13100103
Particle Physics
Searches for physics beyond the standard model come in many forms, from terrestrial probes to astroparticle experiments and cosmological observations. Efforts to combine multiple search channels in 'global fits' to new physics scenarios typically consider only a subset of the available channels. Astroparticle searches in particular are usually only included in a very approximate way, if at all. In this talk I will review recent progress in including detailed gamma-ray, neutrino and CMB searches for dark matter in global fits. I will also preview some of the future developments and challenges in this field, where the applicability of global fits will move well beyond the small range of constrained supersymmetric models they have so far mostly been applied to.
Electroweak Cogenesis and a CP Violating Higgs Boson
September 24, 2013

PIRSA:13090077
Particle Physics
We propose a simple renormalizable model of baryogenesis and asymmetric dark matter generation at the electroweak phase transition. Our setup utilizes the two Higgs doublet model plus two complex gauge singlets, the lighter of which is stable dark matter. The dark matter is charged under a global symmetry that is broken in the early universe but restored during the electroweak phase transition. Because the ratio of baryon and dark matter asymmetries is controlled by model parameters, the dark matter need not be light. Thus, new force carriers are unnecessary and the symmetric dark matter abundance can be eliminated via Higgs portal interactions alone. The dark matter mass is also constrained within a window around the weak scale. One of the main predictions of this model is CP violating Higgs signals at the LHC and future colliders.
The Era of Three Generations: Possible hints from neutrinos in elucidating the matter/antimatter asymmetry of the Universe
September 11, 2013

PIRSA:13090065
Particle Physics
Despite being one of the most abundant constituents of the Universe and more than a half a century of study, some of the most fundamental properties of the neutrino have only been recently uncovered, and others still remain unresolved. I will discuss important developments in the phenomenon of neutrino oscillations, a transmutation process that allows neutrinos to change between three types as they propagate in time. In particular, recent discoveries have opened up the possibility of CP violation in neutrino oscillations, asymmetries in the behavior of neutrinos and their anti-matter counterparts. CP violation, along with other unresolved properties of the neutrino, may play a central role in how the universe came to a matter-dominated state. I will also discuss a new generation of experiments that may allow us to establish whether CP violation does indeed occur in neutrino oscillations.
The local Callan-Symanzik equation: structure and applications

Boaz Keren-Zur
L'Ecole Polytechnique Federale de Lausanne (EPFL)
September 06, 2013

PIRSA:13090067
Particle Physics
The local Callan-Symanzik equation describes the response of a quantum field theory to local scale transformations in the presence of background sources. The consistency conditions associated with this anomalous equation can be used to derive powerful constraints on RG flows. We will discuss various aspects of the equation and present new results regarding the structure of the anomaly. We then use the equation to write correlation functions of the trace of the energy-momentum tensor off-criticality.
Bottom-up Naturalness

Sonia El Hedri
Stanford University
August 27, 2013

PIRSA:13080056
Particle Physics
We study the naturalness problem using a model independent bottom up approach by considering models where only the interaction terms needed to cancel the Higgs quadratic divergences are present. If quadratic divergences are canceled by terms linear in the Higgs field, then the collider phenomenology is well covered by current electroweakino and fourth generation searches. If quadratic divergences are canceled by terms bilinear in the Higgs field, then the signatures are highly dependent on the quantum numbers of the new particles. Precision Higgs measurements can reveal the presence of new particles with either vevs or Standard Model charges. If the new particles are scalar dark matter candidates, their direct and indirect detection signatures will be highly correlated and within the reach of XENON100 and Fermi. Observation at one of these experiments would imply observation at the other one. Observable LHC decay channels can also arise if the new particles mix with lighter states. This decay channel involves only the Higgs boson and not the gauge bosons. Observation of such decays would give evidence that the new particle is tied to the naturalness problem.

Title	Speaker(s)	Date	Talk Type	Info link
Spin and Long-Range Forces: The Unfinished Tale of the Last Massless Particle	Natalia Toro	2013-11-13	Scientific Series	View details
Baryogenesis from WIMPs		2013-11-12	Scientific Series	View details
Induced Electroweak Symmetry Breaking and Supersymmetry	Jamison Galloway	2013-11-05	Scientific Series	View details
Split Dirac Supersymmetry and a Higgsino LSP		2013-11-01	Scientific Series	View details
Gravity and the Search for New Physics with Cosmology	Kris Sigurdson	2013-10-30	Scientific Series	View details
Minimal Distances and the RG Flow		2013-10-29	Scientific Series	View details
Heavy particle effective field theory: formalism, dark matter and the proton size puzzle	Richard Hill	2013-10-18	Scientific Series	View details
Including astroparticle observables in global fits to new physics scenarios	Patrick Scott	2013-10-15	Scientific Series	View details
Electroweak Cogenesis and a CP Violating Higgs Boson		2013-09-24	Scientific Series	View details
The Era of Three Generations: Possible hints from neutrinos in elucidating the matter/antimatter asymmetry of the Universe		2013-09-11	Scientific Series	View details
The local Callan-Symanzik equation: structure and applications	Boaz Keren-Zur	2013-09-06	Scientific Series	View details
Bottom-up Naturalness	Sonia El Hedri	2013-08-27	Scientific Series	View details

Particle Physics

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