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SUMMARY:Gauge-independence of tunneling rates (15' + 5')
DTSTART;VALUE=DATE-TIME:20160806T142000Z
DTEND;VALUE=DATE-TIME:20160806T144000Z
DTSTAMP;VALUE=DATE-TIME:20200918T230135Z
UID:indico-contribution-95231-1071598@indico.cern.ch
DESCRIPTION:Speakers: Carlos Tamarit (IPPP Durham)\nDespite the gauge depe
ndence of the effective action at zero and finite temperature\, it is show
n that it leads to tunneling and nucleation rates that remain independent
of the choice of gauge-fixing. Taking as a starting point the path integra
l that defines the transition amplitude from a false vacuum to itself\, a
careful treatment of the boundary conditions and the gauge-fixing allows t
o show that decay rates are exactly determined by the effective action ev
aluated at a generalized bounce configuration. The latter is a solution to
the quantum equations of motion\, with\nboundary conditions fixed by the
false vacuum. The resulting tunneling rate is gauge-independent\, as the
Nielsen identities imply that the explicit gauge dependence in the effecti
ve action is exactly cancelled by the gauge dependence of the solution. Th
is \nholds for any election of gauge-fixing that leads to an invertible F
addeev-Popov matrix. The result is nonperturbative and model-independent\,
and also clarifies how to incorporate\nradiative corrections in tunneling
calculations.\n\nhttps://indico.cern.ch/event/432527/contributions/107159
8/
LOCATION: Superior A
URL:https://indico.cern.ch/event/432527/contributions/1071598/
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BEGIN:VEVENT
SUMMARY:Towards regularized higher-order computations in QFT without DREG
(15' + 5')
DTSTART;VALUE=DATE-TIME:20160806T171500Z
DTEND;VALUE=DATE-TIME:20160806T173500Z
DTSTAMP;VALUE=DATE-TIME:20200918T230135Z
UID:indico-contribution-95231-1072038@indico.cern.ch
DESCRIPTION:Speakers: German Sborlini (IFIC-Valencia)\nIn this talk\, we r
eview the basis of the loop-tree duality theorem\, which allows to rewrite
loop level amplitudes in terms of tree-level like structures. Since the l
oop measure is converted into a phase-space one\, both virtual and real co
ntributions are expressible using the same integration variables. A physic
ally motivated momentum mapping allows to generate the real emission proce
ss starting from the Born kinematics and the loop momenta. The integrand-l
evel combination leads to regular functions\, which can be integrated with
out using dimensional regularization (DREG) and correctly reproduce the fi
nite higher-order corrections to physical observables. We explain the impl
ementation of this novel approach to compute some physical processes\, and
we show how to deal with both IR and UV divergences without using DREG.\n
\nhttps://indico.cern.ch/event/432527/contributions/1072038/
LOCATION: Superior A
URL:https://indico.cern.ch/event/432527/contributions/1072038/
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BEGIN:VEVENT
SUMMARY:Open Effective Field Theories from Integrating Out High Momenta fr
om Inelastic Reactions (15' + 5')
DTSTART;VALUE=DATE-TIME:20160806T163500Z
DTEND;VALUE=DATE-TIME:20160806T165500Z
DTSTAMP;VALUE=DATE-TIME:20200918T230135Z
UID:indico-contribution-95231-1071722@indico.cern.ch
DESCRIPTION:Speakers: Eric Braaten (Ohio State University)\nEffective fiel
d theories have often been applied to systems with inelastic reactions tha
t produce particles with large momenta outside the domain of validity of t
he effective theory. The effects of the inelastic reactions have been tak
en into account in previous work by adding local anti-Hermitian terms to t
he effective Hamiltonian density. Here we show that an additional modific
ation is required in equations governing the density matrix when multi-par
ticle states are considered. We define an effective density matrix by trac
ing out states containing high-momentum particles\, and show that it satis
fies a Lindblad equation\, with Lindblad operators determined by the anti-
Hermitian terms in the effective Hamiltonian density.\n\nhttps://indico.ce
rn.ch/event/432527/contributions/1071722/
LOCATION: Superior A
URL:https://indico.cern.ch/event/432527/contributions/1071722/
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BEGIN:VEVENT
SUMMARY:The Dirac Equation in Low Energy Condensed Matter Physics (15' + 5
')
DTSTART;VALUE=DATE-TIME:20160806T144000Z
DTEND;VALUE=DATE-TIME:20160806T150000Z
DTSTAMP;VALUE=DATE-TIME:20200918T230135Z
UID:indico-contribution-95231-1071529@indico.cern.ch
DESCRIPTION:Speakers: John Swain (Northeastern University (US))\nElectrons
in low energy condensed matter physics are typically treated using\nthe
non relativistic Schrodinger or Pauli equations\, with relativistic effe
cts\nincluded\, if at all\, via corrections of order v/c. We show that usi
ng the full Dirac\nequation with 4-component spinors leads to a number of
important qualitative\neffects and\, perhaps surprisingly\, some striking
simplifications over the\nconventional lower energy treatments\, even for
nuclei with Z>2.\n\nhttps://indico.cern.ch/event/432527/contributions/107
1529/
LOCATION: Superior A
URL:https://indico.cern.ch/event/432527/contributions/1071529/
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BEGIN:VEVENT
SUMMARY:Correspondence between Solutions of Scattering Equations and Scatt
ering Amplitudes in Four Dimensions (15' + 5')
DTSTART;VALUE=DATE-TIME:20160806T165500Z
DTEND;VALUE=DATE-TIME:20160806T171500Z
DTSTAMP;VALUE=DATE-TIME:20200918T230135Z
UID:indico-contribution-95231-1071728@indico.cern.ch
DESCRIPTION:Speakers: Yijian Du (Deparment of Physics\, Wuhan University)\
, Yong-Shi Wu (University of Utah and Fudan University)\nWe study in detai
l the explicit correspondence between solutions of the scattering equation
s and scattering amplitudes in four dimensions. We have established an in
teresting pattern in the solutions of the scattering equations. In particu
lar\, the MHV Yang-Mills amplitude\, calculated from the CHY formalism\, h
as support on only one particular well-behaved solution. For NMHV amplitud
es and beyond\, each of them can be obtained from an exclusive set of solu
tions\, which do not intersect with others. Thus each solution corresponds
to a basis amplitude\, from which all the amplitudes can be constructed.
We also attempt to give a geometric characterization of the sectors of sol
utions of the scattering equations.\n\nhttps://indico.cern.ch/event/432527
/contributions/1071728/
LOCATION: Superior A
URL:https://indico.cern.ch/event/432527/contributions/1071728/
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BEGIN:VEVENT
SUMMARY:Sub-Leading Effects and the Field Range in Axion Inflation (15' +
5')
DTSTART;VALUE=DATE-TIME:20160806T161500Z
DTEND;VALUE=DATE-TIME:20160806T163500Z
DTSTAMP;VALUE=DATE-TIME:20200918T230135Z
UID:indico-contribution-95231-1071913@indico.cern.ch
DESCRIPTION:Speakers: Ivonne Zavala (Swansea University)\nAn attractive ca
ndidate for the inflaton is an axion slowly rolling down a flat potential
protected by a perturbative shift symmetry. Realisations of this idea howe
ver 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 ov
erall effect is to enhance the number of e-folds of inflation. Sufficient
inflation is therefore achieved for smaller field ranges compared to the p
otential without such corrections. Thus\, both single-field chaotic and na
tural inflation in UV complete theories like string theory\, can be restor
ed into the favoured region of current observations with distinctive signa
tures. Tensor modes result un-observably small\, but there is a large neg
ative running of the spectral index. Remarkably\, natural inflation can b
e achieved with sub-Planckian axion decay constants.\n\nhttps://indico.cer
n.ch/event/432527/contributions/1071913/
LOCATION: Superior A
URL:https://indico.cern.ch/event/432527/contributions/1071913/
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SUMMARY:Extension of the CPT Theorem to non-Hermitian Hamiltonians and Uns
table States (15' + 5')
DTSTART;VALUE=DATE-TIME:20160806T150000Z
DTEND;VALUE=DATE-TIME:20160806T152000Z
DTSTAMP;VALUE=DATE-TIME:20200918T230135Z
UID:indico-contribution-95231-1072005@indico.cern.ch
DESCRIPTION:Speakers: Philip Mannheim (University of Connecticut)\nWe exte
nd the CPT theorem to quantum field theories with non-Hermitian Hamiltonia
ns and unstable states. Our derivation is a quite minimal one as it requir
es only the time-independent evolution of scalar products\, invariance und
er complex Lorentz transformations\, and a non-standard but nonetheless pe
rfectly legitimate interpretation of charge conjugation as an antilinear o
perator. The first of these requirements does not force the Hamiltonian to
be Hermitian. Rather\, it forces its eigenvalues to either be real or to
appear in complex conjugate pairs\, forces the eigenvectors of such conjug
ate pairs to be conjugates of each other\, and forces the Hamiltonian to
admit of an antilinear symmetry. The latter two requirements then force th
is antilinear symmetry to be CPT\, while forcing the Hamiltonian to be rea
l rather than Hermitian. Our work justifies the use of the CPT theorem in
establishing the equality of the lifetimes of unstable particles that are
charge conjugates of each other. We show that the Euclidean time path inte
grals of a CPT-symmetric theory must always be real. In the quantum-mechan
ical limit the key results of the PT symmetry program of Bender and collab
orators are recovered\, with the C-operator of the PT symmetry program bei
ng identified with the linear component of the charge conjugation operator
.\n\nhttps://indico.cern.ch/event/432527/contributions/1072005/
LOCATION: Superior A
URL:https://indico.cern.ch/event/432527/contributions/1072005/
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BEGIN:VEVENT
SUMMARY:Near-BPS Skyrme Models: recent developments (15' + 5')
DTSTART;VALUE=DATE-TIME:20160806T152000Z
DTEND;VALUE=DATE-TIME:20160806T154000Z
DTSTAMP;VALUE=DATE-TIME:20200918T230135Z
UID:indico-contribution-95231-1072562@indico.cern.ch
DESCRIPTION:Speakers: Luc Marleau (Université Laval)\nWe present our most
recent results regarding Near-BPS Skyrmions and argue that they provide a
n improved description of nucleons and nuclei. For some years now\, the Sk
yrme Model and extensions have been considered natural candidates for a lo
w-energy effective theory of QCD\, a point of view supported by results co
ming from 1/N expansion and holographic QCD. This framework leads to an at
tractive picture: baryons (and nuclei) emerge as topological solitons with
a topological number identified to the baryon number. But the most naive
Skyrme Model extensions have been plagued with the same problem: they pred
ict large binding energies for the nuclei. On the other hand\, the solutio
ns that arise from the more recently proposed near-BPS Skyrme models nearl
y saturate the Bogomol’nyi bound which means that by construction there
must have small binding energies. We address a number of issues related to
the strength of each terms in the Lagrangian and the form of the potentia
l of these models with their consequences on the baryon density configurat
ions\, Coulomb energies\, isospin symmetry breaking\, binding energies and
mean radius of the nuclei\, the pion mass and more.\n\nhttps://indico.cer
n.ch/event/432527/contributions/1072562/
LOCATION: Superior A
URL:https://indico.cern.ch/event/432527/contributions/1072562/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The fate of the Higgs Vacuum (15' + 5')
DTSTART;VALUE=DATE-TIME:20160806T140000Z
DTEND;VALUE=DATE-TIME:20160806T142000Z
DTSTAMP;VALUE=DATE-TIME:20200918T230135Z
UID:indico-contribution-95231-2204914@indico.cern.ch
DESCRIPTION:Speakers: Ruth Gregory (Durham University)\nNow that the Higgs
boson has finally been detected\, its mass suggests that we are in a regi
on 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 instanton\, however\, this assumes our universe is featureless. Ju
st as impurities can act as nucleation sites of a phase transition\, gravi
tational impurities\, in the guise of black holes\, can act as bubble nucl
eation sites for false vacuum decay. I will describe how a black hole can
significantly enhance the probability of vacuum decay\, and discuss implic
ations for the Higgs vacuum.\n\nhttps://indico.cern.ch/event/432527/contri
butions/2204914/
LOCATION: Superior A
URL:https://indico.cern.ch/event/432527/contributions/2204914/
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