BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Convergence of the light-front coupled-cluster method
DTSTART;VALUE=DATE-TIME:20180515T180000Z
DTEND;VALUE=DATE-TIME:20180515T182000Z
DTSTAMP;VALUE=DATE-TIME:20211128T045101Z
UID:indico-contribution-644-3134@indico.jlab.org
DESCRIPTION:Speakers: Sophia Chabysheva (University of Minnesota-Duluth)\n
We explore the convergence of the light-front coupled-cluster (LFCC) metho
d in the context of two-dimensional quenched scalar Yukawa theory. This t
heory is simple enough for higher-order LFCC calculations to be relatively
straightforward. The quenching is to maintain stability\; the spectrum o
f the full theory with pair creation and annihilation is unbounded from be
low. The basic interaction in the quenched theory is only emission and ab
sorption of a neutral scalar by the complex scalar. The LFCC method build
s the eigenstate with one complex scalar and a cloud of neutrals from a va
lence state that is just the complex scalar and the action of an exponenti
ated operator that creates neutrals. The lowest order LFCC operator creat
es one\; we add the next order\, a term that creates two. At this order t
here is a direct contribution to the wave function for two neutrals and on
e complex scalar and additional contributions to all higher Fock states.
Results for the lowest order and this new second order approximation are c
ompared with those obtained with standard Fock-state expansions.\n\nhttps:
//indico.jlab.org/event/252/contributions/3134/
LOCATION:Jefferson Lab - CEBAF Center F113
URL:https://indico.jlab.org/event/252/contributions/3134/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Recursion relations for off-shell amplitudes on the light-front an
d Wilson lines
DTSTART;VALUE=DATE-TIME:20180515T182000Z
DTEND;VALUE=DATE-TIME:20180515T184000Z
DTSTAMP;VALUE=DATE-TIME:20211128T045101Z
UID:indico-contribution-644-3136@indico.jlab.org
DESCRIPTION:Speakers: Anna Stasto (Penn State)\nIn this presentation we wi
ll discuss some interesting properties of the off-shell scattering amplit
udes in the framework of the light-front perturbation theory. It is shown
that certain recursion relation between tree level off-shell amplitudes in
this formalism actually resums whole classes of graphs into a Wilson line
. More precisely\, we demonstrate a correspondence between the light-front
methods for the computation of the off-shell amplitudes and the approach
which makes use of the matrix elements of straight infinite Wilson lines\,
which are manifestly gauge invariant objects and satisfy Ward identities.
In addition\, we demonstrate that such structure is helicity independen
t and emerges from analytic properties of matrix elements of Wilson line o
perators\, where the slope of the straight gauge path is shifted in a cert
ain complex direction. This is similar to the procedure leading to the Bri
tto-Cachazo-Feng-Witten (BCFW) recursion\, with the difference that a co
mplex shift is applied to the Wilson line slope instead of the external mo
menta.\n\nhttps://indico.jlab.org/event/252/contributions/3136/
LOCATION:Jefferson Lab - CEBAF Center F113
URL:https://indico.jlab.org/event/252/contributions/3136/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Fermion-antifermion phenomenology in Minkowski space
DTSTART;VALUE=DATE-TIME:20180515T192000Z
DTEND;VALUE=DATE-TIME:20180515T194000Z
DTSTAMP;VALUE=DATE-TIME:20211128T045101Z
UID:indico-contribution-644-3139@indico.jlab.org
DESCRIPTION:Speakers: Jorge Henrique De Alvarenga Nogueira (Instituto Tecn
ológico de Aeronáutica & 'La Sapienza' Università di Roma & INFN\, Sezi
one di Roma)\nThe advent of approaches based on the Euclidean space for st
udying\n hadron observables\, such as lattice QCD and Schwinger-Dyson equa
tions\, \n has been remarkable and responsible to produce important unders
tanding\n on the non-perturbative dynamical regime. \n\nHowever\, the qua
ntum field theory formulation in Minkowski space has subtle and\nessential
signatures as\, e.g.\, the ones related to the spin degrees of\n freedom
\, that require to be evaluated in a theoretical framework developed \n in
the physical space\, where the dynamical processes take place. One import
ant tool \n is the Fock space expansion\, which allows one to construct a
probabilistic \n description of hadrons and to explore relativistic effe
cts on the dynamics \n as\, e.g.\, through the analysis of the electromagn
etic (EM) form factors beyond the impulse approximation [1].\n\nIn recent
years\, studies based on actual solutions of the homogeneous\nBethe-Salpet
er equation directly in Minkowski space have becoming available. \nThis a
chievement makes\nfeasible to start phenomenological investigations of th
e hadron structure\, shedding light on the intrinsic dynamics that is form
ally and conceptually connected with the physical space\, i.e. the Minkows
ki one [2\,3]. \n The new framework for solving the Bethe-Salpeter equatio
n has a main \n ingredient given by the the so-called Nakanishi Integral R
epresentation of\n the Bethe-Salpeter amplitude that allows one to expli
citly deal with its\n analytic structure\, without resorting to the Wick
rotation. \n\nIn order to illustrate the phenomenological potential of the
aforementioned \nframework we explore the $0^-$ quark-antiquark bound sta
te\, by the solution of the coupled integral equations. The study is done
in the ladder\napproximation\, based on the suppression of the cross-ladde
r contribution found for bosonic systems [2].\n By taking the constituents
and exchanged-boson masses from\, \n e.g.\, lattice calculations\, dynami
cal observables \n like the light-cone momentum distributions are predicte
d. \n The decay constant $f_\\pi$ is also computed\, as well as the elec
tromagnetic form factors. Such a preliminary investigation of the phenomen
ology of what we call mock pion will allow\n to settle the framework where
one can develop more and more realistic description in Minkowski space.\n
\n[1] V. Gigante\, J. H. Alvarenga Nogueira\, E. Ydrefors\, C. Gutierrez\,
V. A. Karmanov and T. Frederico\, Phys. Rev. D 95\, 056012 (2017)\n\n[2]
J. H. Alvarenga Nogueira\, Chueng-Ryong Ji\, E. Ydrefors and T. Frederico\
, Phys. Lett. B 777\, 207-211 (2018)]\n\n[3] W. de Paula\, T. Frederico\,
G. Salmè\, M. Viviani\, R. Pimentel\, \n%Fermionic bound states in Minkow
ski space: light-cone singularities and structure\, \nEur. Phys. J. C 77\,
764 (2017)\n\nhttps://indico.jlab.org/event/252/contributions/3139/
LOCATION:Jefferson Lab - CEBAF Center F113
URL:https://indico.jlab.org/event/252/contributions/3139/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Energy-momentum tensor for unpolarized proton target
DTSTART;VALUE=DATE-TIME:20180515T190000Z
DTEND;VALUE=DATE-TIME:20180515T192000Z
DTSTAMP;VALUE=DATE-TIME:20211128T045101Z
UID:indico-contribution-644-3168@indico.jlab.org
DESCRIPTION:Speakers: Arkadiusz Trawinski (CEA-Saclay)\nThe expectation va
lue of the quantum energy-momentum tensor (EMT) for an unpolarized proton
target in the Breit frame can be matched with an anisotropic perfect fluid
EMT. This matching offers the possibility of interpreting the EMT form fa
ctors in terms of the internal energy and transverse/radial pressure insid
e an unpolarized proton target.\n\nThe generalization of this result to a
more general class of frames leads to additional terms in the anisotropic
fluid EMT\, which can be related to the rotation and spin of proton.\n\nWe
illustrate these results using current phenomenological knowledge of the
EMT form factors.\n\nhttps://indico.jlab.org/event/252/contributions/3168/
LOCATION:Jefferson Lab - CEBAF Center F113
URL:https://indico.jlab.org/event/252/contributions/3168/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The MHV Lagrangian and hidden Wilson lines
DTSTART;VALUE=DATE-TIME:20180515T184000Z
DTEND;VALUE=DATE-TIME:20180515T190000Z
DTSTAMP;VALUE=DATE-TIME:20211128T045101Z
UID:indico-contribution-644-3210@indico.jlab.org
DESCRIPTION:Speakers: Piotr Kotko (Institute of Nuclear Physics\, PAN)\nTh
e MHV Lagrangian is the Yang-Mills Lagrangian quantized on the light\ncone
\, where the two transverse gluonic degrees of freedom have been\ncanonica
lly transformed to a set of new fields\, in which the vertices\nbecome a s
eries of the maximally helicity violating (MHV) amplitudes\ncontinued off-
shell. The usage of the MHV vertices to construct\namplitudes is also know
n as the Cachazo-Svrcek-Witten (CSW) method.\nAfter a review of these idea
s I will discuss properties of the\ntransformation leading to the MHV Lagr
angian\, in particular I will argue\nthat the solution to the field transf
ormation has a form of certain Wilson line.\nI will also discuss some cons
equences of that fact.\n\nhttps://indico.jlab.org/event/252/contributions/
3210/
LOCATION:Jefferson Lab - CEBAF Center F113
URL:https://indico.jlab.org/event/252/contributions/3210/
END:VEVENT
END:VCALENDAR