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 1429

New strong interactions and the t t-bar asymmetry

Joachim Brod University of Cincinnati
May 13, 2014

PIRSA:14050092
Particle Physics
Noncommutative geometry and the symmetries of the standard model

Fedele Lizzi University of Naples Federico II
May 06, 2014

PIRSA:14050031
Particle Physics

Cosmology
Boson Tagging with Wavelets

William Shepherd University of California, Santa Cruz
April 15, 2014

PIRSA:14040063
Particle Physics
GeV Gamma-Rays from the Central Milky Way and the Case for Annihilating Dark Matter

Tracy Slatyer Massachusetts Institute of Technology (MIT) - Department of Physics
March 26, 2014

PIRSA:14030120
Particle Physics
Naturalness and the Weak Gravity Conjecture

Clifford Cheung California Institute of Technology (Caltech) - Physics Office
March 25, 2014

PIRSA:14030119
Particle Physics
Exact results in supersymmetric gauge theories in various dimensions

Sara Pasquetti University of Milan
March 19, 2014

PIRSA:14030084
Particle Physics
Before the Bang

Raman Sundrum University of Maryland, College Park
March 18, 2014

PIRSA:14030113
Particle Physics
Large Tensor-to-Scalar Ratio in Small-Field Inflation

Takeshi Kobayashi SISSA International School for Advanced Studies
February 25, 2014

PIRSA:14020152
Particle Physics

Cosmology
Sequestering the Standard Model Vacuum Energy

Nemanja Kaloper University of California, Davis
February 21, 2014

PIRSA:14020109
Particle Physics
Gaugino physics of split supersymmetry spectrum at the LHC and future proton colliders

Sunghoon Jung Korea Institute for Advanced Study
January 16, 2014

PIRSA:14010103
Particle Physics
Beyond the Standard Paradigm

Paul Langacker Institute for Advanced Study (IAS)
January 15, 2014

PIRSA:13010116
Particle Physics
No GUTs, All Glory: Charge Quantization and the Standard Model from Nonlinear Sigma Models

John Kehayias University of Tokyo
December 06, 2013

PIRSA:13120056
Particle Physics

New strong interactions and the t t-bar asymmetry

Joachim Brod University of Cincinnati
May 13, 2014

PIRSA:14050092
Particle Physics
The CDF and D0 experiments at Tevatron measure a top-quark forward-backward
asymmetry significantly larger than the standard-model prediction.
We construct a model that involves new strong interactions at the electroweak scale
and can explain the measured asymmetry. Our model possesses a flavor symmetry
which allows to evade flavor and collider constraints, while it still permits flavor-violating
couplings of order 1 which are needed to generate the asymmetry via light t-channel vectors.
Noncommutative geometry and the symmetries of the standard model

Fedele Lizzi University of Naples Federico II
May 06, 2014

PIRSA:14050031
Particle Physics

Cosmology
I will describe Connes approach to the standard model based on spectral noncommutative geometry with particular emphasis on the symmetries. The model poses constraints which are satisfied by the standard model group, and does not leave much room for other possibilities. There is however a possibility for a larger symmetry (the ``grand algebra'') which may also be instrumental to obtain the correct mass of the Higgs.
Boson Tagging with Wavelets

William Shepherd University of California, Santa Cruz
April 15, 2014

PIRSA:14040063
Particle Physics
I'll present a proof-of-concept new technique for tagging boosted objects which decay into two colored particles based on the wavelet transform. It is able to moderately improve the sensitivity of searches for such particles by 6-7%. I will also discuss future directions of applicability.
GeV Gamma-Rays from the Central Milky Way and the Case for Annihilating Dark Matter

Tracy Slatyer Massachusetts Institute of Technology (MIT) - Department of Physics
March 26, 2014

PIRSA:14030120
Particle Physics
Past studies have identified a spatially extended excess of ~1-3 GeV gamma rays from the Galactic Center and inner Galaxy, consistent with the emission expected from annihilating thermal relic dark matter. I will describe recent improvements in the characterization of this signal, which demonstrate that it is spherically symmetric, centered on the Galactic Center, and with a spatial profile consistent with annihilation from a cusped NFW profile. The excess can be detected out to 10 degrees from the Galactic Center, which poses challenges for a millisecond pulsar origin; I will discuss the implications of a dark matter interpretation.
Naturalness and the Weak Gravity Conjecture

Clifford Cheung California Institute of Technology (Caltech) - Physics Office
March 25, 2014

PIRSA:14030119
Particle Physics
The weak gravity conjecture (WGC) asserts a powerful consistency condition on gauge theories coupled to quantum gravity: an Abelian, long-range force requires a state of charge q and mass m such that q > m/mPl. Failure of this condition implies the existence of stable black hole remnants and is in tension with no-hair theorems. In this paper, we argue that the WGC creates a non- perturbative obstruction to naturalness, which is the notion that dimensionless coefficients should take on O(1) values in the absence of enhanced symmetry. As an illustration, we show that for scalar quantum electrodynamics, a natural spectrum can actually be forbidden by the WGC, which bounds a radiatively unstable quantity, m, by a radiatively stable quantity, q. More generally, the WGC can be at odds with naturalness in any theory containing charged fundamental scalars. We extend the conditions of the WGC to more complicated theories with multiple gauge symmetries and particles. Finally, we discuss implications for the hierarchy problem and construct a simple model in which the natural value of the electroweak scale—at the cutoff—is forbidden by the WGC.
Exact results in supersymmetric gauge theories in various dimensions

Sara Pasquetti University of Milan
March 19, 2014

PIRSA:14030084
Particle Physics
One of the central challenges in theoretical physics is to develop non-perturbative methods to describe quantitatively the dynamics of strongly coupled quantum fields. Much progress in this direction has been made for theories with a higher degree of symmetry, such as conformal symmetry or supersymmetry. In recent years the method of localisation has allowed to obtain a great deal of exact results for supersymmetric gauge theories in various dimensions which has led to the discovery of new surprising correspondences such as the celebrated Alday-Gaiotto-Tachikawa correspondence. I will review some recent results which indicate that partition functions of supersymmetric theories formulated on compact manifolds can be expressed in terms of a small set of fundamental building blocks.
Before the Bang

Raman Sundrum University of Maryland, College Park
March 18, 2014

PIRSA:14030113
Particle Physics
The simplest black hole solution in asymptotic AdS spacetime, the eternal 3-dimensional BTZ black hole, is studied from the viewpoint of AdS/CFT duality. We identify a class of non-local correlators on the CFT side that allow us to generalize the notion of quantum gravity "S-matrix" to scattering inside the horizon. Since the interior of the horizon is a cosmological spacetime with a big bang/crunch-like singularity, our construction can be interpreted as identifying generally coordinate invariant observables of quantum gravity in a simple cosmology. We show in a certain precise sense, that these holographic observables lie "before the big bang" in a region of spacetime containing closed timelike curves. A central tool in our analysis is the realization of BTZ as a quotient of 3-dimensional AdS.
Large Tensor-to-Scalar Ratio in Small-Field Inflation

Takeshi Kobayashi SISSA International School for Advanced Studies
February 25, 2014

PIRSA:14020152
Particle Physics

Cosmology
The production of gravitational waves from cosmic inflation > is normally bounded by the inflaton field excursion. This relation, > which is often referred to as the Lyth bound, claims that > observationally large gravitational waves are produced only if the > inflaton has a super-Planckian field range. In this talk I will point > out that this general belief is not necessarily true when there are > additional light fields producing density perturbations. Perturbations > seeded by the inflaton can be suppressed under such situations, thus > allow large gravitational waves to be produced even from small-field (i.e. > sub-Planckian) inflation. I will also show that the field bound is > taken over by the light field when the inflaton-induced perturbations > are suppressed, thus present a generalized form of the Lyth bound that > applies to the total field space. The calculations are rather simple, > so I will explain my work on a blackboard.
Sequestering the Standard Model Vacuum Energy

Nemanja Kaloper University of California, Davis
February 21, 2014

PIRSA:14020109
Particle Physics
We propose a very simple reformulation of General Relativity, which completely sequesters from gravity {\it all} of the vacuum energy from a matter sector, including all loop corrections and renders all contributions from phase transitions automatically small. The idea is to make the dimensional parameters in the matter sector functionals of the 4-volume element of the universe. For them to be nonzero, the universe should be finite in spacetime. If this matter is the Standard Model of particle physics, our mechanism prevents any of its vacuum energy, classical or quantum, from sourcing the curvature of the universe. The mechanism is consistent with the large hierarchy between the Planck scale, electroweak scale and curvature scale, and early universe cosmology, including inflation. Consequences of our proposal are that the vacuum curvature of an old and large universe is not zero, but very small, that wDE≃−1 is a transient, and that the universe will collapse in the future.
Gaugino physics of split supersymmetry spectrum at the LHC and future proton colliders

Sunghoon Jung Korea Institute for Advanced Study
January 16, 2014

PIRSA:14010103
Particle Physics
Discovery of the Higgs boson and lack of discovery of superpartners in the first run at LHC are both predictions of split supersymmetry with thermal dark matter. We discuss what it would take to find gluinos at hadron supercolliders, including the LHC at 14 TeV center of mass energy, and future pp colliders at 100 TeV and 200 TeV. We generalize the discussion by re-expressing the search capacity in terms of gluino to lightest superpartner mass ratio, and apply results to other scenarios, such as gauge mediation and mirage mediation. In those models, distinctive gaugino mass ratios arise at leading order, but can be significantly modified by large logarithmic quantum corrections from split spectrum.
Beyond the Standard Paradigm

Paul Langacker Institute for Advanced Study (IAS)
January 15, 2014

PIRSA:13010116
Particle Physics
I reexamine the current situation in particle and neutrino physics from a top-down perspective, discussing such underlying issues as uniqueness versus environment, minimality versus remnants, and naturalness versus tuning.
No GUTs, All Glory: Charge Quantization and the Standard Model from Nonlinear Sigma Models

John Kehayias University of Tokyo
December 06, 2013

PIRSA:13120056
Particle Physics
I will present recent and ongoing work in collaboration with Tsutomu Yanagida and Simeon Hellerman (arXiv:1309.0692 and 1312.xxxx) on a new way to obtain charge quantization, without a GUT or monopole solution. In the CP^1 model, SU(2)_G/U(1)_H, consistency conditions for a charged field and its transformation properties over the entire group manifold lead to a charge quantization condition. By gauging the U(1)_H and identifying it with hypercharge, we find charge quantization in the SM without a monopole or GUT, purely from the structure and dynamics of the nonlinear sigma model. This is easily extended to CP^2 and general CP^k models. Phenomenologically, the CP^1 model has a fractionally charged stable Nambu-Goldstone boson (NGB), which has intriguing applications to nuclear physics and dark matter. The CP^2 model has the Higgs as the NGB. With some additional minor assumptions, anomaly freedom then leads to the matter content of a generation in the SM.

Title	Speaker(s)	Date	Talk Type	Info link
New strong interactions and the t t-bar asymmetry	Joachim Brod	2014-05-13	Scientific Series	View details
Noncommutative geometry and the symmetries of the standard model	Fedele Lizzi	2014-05-06	Scientific Series	View details
Boson Tagging with Wavelets	William Shepherd	2014-04-15	Scientific Series	View details
GeV Gamma-Rays from the Central Milky Way and the Case for Annihilating Dark Matter	Tracy Slatyer	2014-03-26	Scientific Series	View details
Naturalness and the Weak Gravity Conjecture	Clifford Cheung	2014-03-25	Scientific Series	View details
Exact results in supersymmetric gauge theories in various dimensions	Sara Pasquetti	2014-03-19	Scientific Series	View details
Before the Bang	Raman Sundrum	2014-03-18	Scientific Series	View details
Large Tensor-to-Scalar Ratio in Small-Field Inflation	Takeshi Kobayashi	2014-02-25	Scientific Series	View details
Sequestering the Standard Model Vacuum Energy	Nemanja Kaloper	2014-02-21	Scientific Series	View details
Gaugino physics of split supersymmetry spectrum at the LHC and future proton colliders	Sunghoon Jung	2014-01-16	Scientific Series	View details
Beyond the Standard Paradigm	Paul Langacker	2014-01-15	Scientific Series	View details
No GUTs, All Glory: Charge Quantization and the Standard Model from Nonlinear Sigma Models	John Kehayias	2013-12-06	Scientific Series	View details

Particle Physics

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