### Conveners

#### Formal Theory Developments: 1

- Ivonne Zavala (Swansea University)
- Ruth Gregory (Durham University)

#### Formal Theory Developments: 2

- Ruth Gregory (Durham University)

Ruth Gregory
(Durham University)

06/08/2016, 09:00

Formal Theory Developments

Oral Presentation

Now that the Higgs boson has finally been detected, its mass suggests that we are in a region of "metastability", with various claims being made about the lifetime of the vacuum. However, the new minimum lies in a Planckian regime, and we would expect gravity to be relevant in any decay process. The decay of a false vacuum is always described by a tunneling process, the Coleman-de Luccia...

Carlos Tamarit
(IPPP Durham)

06/08/2016, 09:20

Formal Theory Developments

Oral Presentation

Despite the gauge dependence of the effective action at zero and finite temperature, it is shown that it leads to tunneling and nucleation rates that remain independent of the choice of gauge-fixing. Taking as a starting point the path integral that defines the transition amplitude from a false vacuum to itself, a careful treatment of the boundary conditions and the gauge-fixing allows to show...

John Swain
(Northeastern University (US))

06/08/2016, 09:40

Formal Theory Developments

Oral Presentation

Electrons in low energy condensed matter physics are typically treated using
the non relativistic Schrodinger or Pauli equations, with relativistic effects
included, if at all, via corrections of order v/c. We show that using the full Dirac
equation with 4-component spinors leads to a number of important qualitative
effects and, perhaps surprisingly, some striking simplifications over...

Prof.
Philip Mannheim
(University of Connecticut)

06/08/2016, 10:00

Formal Theory Developments

Oral Presentation

We extend the CPT theorem to quantum field theories with non-Hermitian Hamiltonians and unstable states. Our derivation is a quite minimal one as it requires only the time-independent evolution of scalar products, invariance under complex Lorentz transformations, and a non-standard but nonetheless perfectly legitimate interpretation of charge conjugation as an antilinear operator. The first of...

Luc Marleau
(Université Laval)

06/08/2016, 10:20

Formal Theory Developments

Oral Presentation

We present our most recent results regarding Near-BPS Skyrmions and argue that they provide an improved description of nucleons and nuclei. For some years now, the Skyrme Model and extensions have been considered natural candidates for a low-energy effective theory of QCD, a point of view supported by results coming from 1/N expansion and holographic QCD. This framework leads to an attractive...

Dr
Ivonne Zavala
(Swansea University)

06/08/2016, 11:15

Formal Theory Developments

Oral Presentation

An attractive candidate for the inflaton is an axion slowly rolling down a flat potential protected by a perturbative shift symmetry. Realisations of this idea however are difficult to embed in string theory. I will show that subleading, but significant non-perturbative corrections to the axion potential can superimpose sharp cliffs and gentle plateaus into the potential, whose overall effect...

Eric Braaten
(Ohio State University)

06/08/2016, 11:35

Formal Theory Developments

Oral Presentation

Effective field theories have often been applied to systems with inelastic reactions that produce particles with large momenta outside the domain of validity of the effective theory. The effects of the inelastic reactions have been taken into account in previous work by adding local anti-Hermitian terms to the effective Hamiltonian density. Here we show that an additional modification is...

Prof.
Yijian Du
(Deparment of Physics, Wuhan University)
, Prof.
Yong-Shi Wu
(University of Utah and Fudan University)

06/08/2016, 11:55

Formal Theory Developments

Oral Presentation

We study in detail the explicit correspondence between solutions of the scattering equations and scattering amplitudes in four dimensions. We have established an interesting pattern in the solutions of the scattering equations. In particular, the MHV Yang-Mills amplitude, calculated from the CHY formalism, has support on only one particular well-behaved solution. For NMHV amplitudes and...

German Sborlini
(IFIC-Valencia)

06/08/2016, 12:15

Formal Theory Developments

Oral Presentation

In this talk, we review the basis of the loop-tree duality theorem, which allows to rewrite loop level amplitudes in terms of tree-level like structures. Since the loop measure is converted into a phase-space one, both virtual and real contributions are expressible using the same integration variables. A physically motivated momentum mapping allows to generate the real emission process...