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BEGIN:VEVENT
SUMMARY:Open Quantum Random Walks
DTSTART;VALUE=DATE-TIME:20110714T094500Z
DTEND;VALUE=DATE-TIME:20110714T100000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-4948@events.saip.org.za
DESCRIPTION:Speakers: Ilya Sinayskiy (School of Physics and NITheP\, Unive
rsity of KwaZulu-Natal)\nQuantum Random Walks have been introduced almost
20 years by Y. Aharonov et al. [Phys. Rev. A\, 48(2):1687–1690\, 1993] a
nd have found wide applications in quantum computing. As is often the case
in quantum theory\, Quantum Walks differ strongly from classical random w
alks. In joint work of S. Attal\, C. Sabot\, F. Petruccione and I. Sinaysk
iy the concept of Open Quantum Random Walks was introduced\, by taking int
o account dissipation and decoherence that occur in open quantum systems.
The connection to classical and unitary random is discussed as well as the
potential of Open Quantum Random Walks for quantum computing and efficien
t quantum transport.\n\nhttps://events.saip.org.za/event/7/contributions/4
948/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/4948/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Mechanical and Structural Properties of the Pt-Ti and Ir-Ti Al
loy Systems
DTSTART;VALUE=DATE-TIME:20110713T121500Z
DTEND;VALUE=DATE-TIME:20110713T123000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-4854@events.saip.org.za
DESCRIPTION:Speakers: Miguel Cavero (University of KwaZulu-Natal)\nAb init
io density functional calculations within the generalised gradient approxi
mation (GGA) have been carried out on a wide range of phases and stoichiom
etries for the platinum-titanium (Pt-Ti) and iridium-titanium (Ir-Ti) allo
y systems\, using the Vienna Ab Initio Simulation Package (VASP). The ela
stic constants and elastic moduli are calculated and the electronic struct
ure and density of states (DOS) are considered to understand the hardness
and stability properties of the alloys.\n\nhttps://events.saip.org.za/even
t/7/contributions/4854/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/4854/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Monte Carlo simulation using GEANT 4 of MuSR
DTSTART;VALUE=DATE-TIME:20110713T114500Z
DTEND;VALUE=DATE-TIME:20110713T120000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-4886@events.saip.org.za
DESCRIPTION:Speakers: Jonathan Hartman (University of Johannesburg)\nGEANT
4 is a C++ library developed by CERN to simulate particle physics experim
ents. However\, GEANT 4 can be also be used for other applications that ne
ed not have anything to do with particle or high-energy physics. Here we d
iscuss an application of GEANT 4 that simulates the EMU Spectrometer for M
uon Spin Relaxation measurements at the ISIS facility in the Rutherford Ap
pleton Laboratory. Both the incident muon and decay positron trajectories
are affected. This changes the stopping location of muons for small sample
s and also the efficiency of the positron detection\, in a strongly field
dependent way. This leads to a systematic field dependent false asymmetry.
The simulation has been performed in support of the interpretation of exp
eriments todetermine the effect on diamond samples doped with muonium\, wh
ich is a known analogue of the hydrogen atom.\n\nhttps://events.saip.org.z
a/event/7/contributions/4886/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/4886/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Giant Graviton on AdS4xCP3
DTSTART;VALUE=DATE-TIME:20110714T064500Z
DTEND;VALUE=DATE-TIME:20110714T070000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-4869@events.saip.org.za
DESCRIPTION:Speakers: Andrea Prinsloo (NITheP\, Stellenbosch University)\n
A new correspondence between type IIA string theory on AdS4×CP3 and an N=
6 Super Chern-Simons-matter theory was proposed by Aharony\, Bergman\, Jaf
feris and Maldacena (ABJM) in 2008. We construct the D4-brane giant gravit
on\, extended and moving in the complex projective space\, which is dual t
o a subdeterminant operator in ABJM theory. This dynamically stable config
uration factorizes at maximum size into two topologically stable D4-branes
(each wrapped on a different CP2 cycle) dual to ABJM dibaryons. We also m
ention our more recent results obtained from an analysis of small fluctuat
ions around this CP3 giant graviton.\n\nhttps://events.saip.org.za/event/7
/contributions/4869/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/4869/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Antimatter production in pp and in heavy-ion collisions at ultrare
lativistic energies
DTSTART;VALUE=DATE-TIME:20110715T091500Z
DTEND;VALUE=DATE-TIME:20110715T094500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5059@events.saip.org.za
DESCRIPTION:Speakers: Jean Cleymans (University of Cape Town)\nOne of the
striking features of particle production at high beam energies\nis the nea
r equal abundance of matter and antimatter in the central rapidity region.
\nIn this paper we would like to study how this symmetry is \nreached as
the beam energy is increased. In particular \nwe quantify explicitly the e
nergy dependence of the approach to matter/antimatter \nsymmetry. \nExpect
ations are presented for the production of more complex forms of\nantimatt
er like antihypernuclei.\n\nhttps://events.saip.org.za/event/7/contributio
ns/5059/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5059/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Successes and Failures of Numerical Solutions to the 1-Dimentional
Marchenko Integral Equation for Quantum Inverse Scattering
DTSTART;VALUE=DATE-TIME:20110713T091500Z
DTEND;VALUE=DATE-TIME:20110713T093000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-4911@events.saip.org.za
DESCRIPTION:Speakers: Serle Shuman (UNISA)\nThe origin of numerical errors
\, which in certain cases lead\nto complete failure of the direct method f
or solving the 1-dimensional Marchenko\nintegral equation\, are investigat
ed. Bargmann and block potentials\, for which exact analytical\nexpression
s exist\, are used to compare the accuracy of numerical results. In\nparti
cular\, numerical results from the Nystrom method are compared to those of
two\nnovel collocation methods. The results indicate that\, for roughly t
he same\ncomputational effort\, the three method may be ranked in order of
increasing accuracy: \nNystrom method\, equidistant collocation method an
d non-equidistant collocation method. \nIn all three cases the origin of t
he failure\, which occurs for barrier-like potentials of relatively \nlarg
e width and height\, may be attributed to the numerical instability introd
uced in both the Fourier \ninversion and the linearization steps. Subseque
ntly these errors produce perturbations on \nthe matrix elements of the in
version matrix\, a matrix which is found to become increasingly \nill-cond
itioned as the height and width of the potential increases. At the current
limits of\nsuccessful inversion\, we attribute the "early" onset of inver
sion failures\, to the\naforementioned matrix element perturbations. Howev
er at still higher potential height\nand width\, the inherent ill-conditio
ning of the inversion matrix alone\, accounts for\nthe inversion failures.
We therefore conclude that there is an inherent upper-bound on the\nappli
cation of the direct inversion method for inverting relatively high and wi
de\npotentials.\n\nhttps://events.saip.org.za/event/7/contributions/4911/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/4911/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Optimised Hyperchaotic Modes of a Triple Pendulum
DTSTART;VALUE=DATE-TIME:20110715T064500Z
DTEND;VALUE=DATE-TIME:20110715T070000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-4917@events.saip.org.za
DESCRIPTION:Speakers: André Botha (Unisa)\nAnalytical equations of motion
\, in the form dxi ⁄ dt = fi(x\,t)\, are derived for a damped harmonical
ly driven triple plane pendulum. This form of the equations clearly displa
ys the nature of the non-linear coupling and provides a basis for physical
interpretation. The equations also facilitate the derivation of the Jacob
ian matrix in analytical form\, a result which is important for the accura
te numerical computation of the Lyapunov exponents. It is shown that sets
of optimised parameters\, such as the lengths and masses of the pendulum\,
may be derived by using the Nelder-Mead simplex optimisation algorithm. T
his method gives precise control over the Lyapunov exponents and may be us
eful in a wide variety of other non-linear applications\, such as those oc
curring in biophysics and information technology (for secure communication
). As an example of the technique it is used to predict periodic and quasi
-periodic orbits of the un-damped pendulum\, as well as its chaotic and hy
perchaotic modes. The maximum positive Lyapunov exponents for the pendulum
are found to vary from zero\, for periodic orbits\, to as high as ten for
the optimised hyperchaotic modes. Numerical simulations\, coded in Python
\, are used to visualise the results. \n\nhttps://events.saip.org.za/event
/7/contributions/4917/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/4917/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Adding Flavour to Nonplanar Integrability
DTSTART;VALUE=DATE-TIME:20110714T061500Z
DTEND;VALUE=DATE-TIME:20110714T063000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-4926@events.saip.org.za
DESCRIPTION:Speakers: Stephanie Smith (University of the Witwatersrand)\nN
=4 SYM theory has been extensively studied in the planar limit. A very\nsi
gnificant result of this study is a map from the planar dilatation\noperat
or to the Hamiltonian of an integrable spin chain. In this talk\nwe consid
er a large N (but not planar) limit of the theory. This is\na considerably
more complicated problem since non-planar corrections\nneed to be summed.
This summation is accomplished by employing the\nrestricted Schur polynom
ials. We give an analytic formula for the\naction of the dilatation operat
or on the resticted Schur polynomials\nand then proceed to calculate the o
ne loop anomalous dimensions.\nOur result shows that the dilatation operat
or reduces to a set of\ndecoupled harmonic oscillators\, generalizing resu
lts known from the\nsector of theory constructed using two complex Higgs f
ields (two flavors)\nto the sector with three complex Higgs fields (three
flavors).\n\nhttps://events.saip.org.za/event/7/contributions/4926/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/4926/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A Quantum Hall Effect without Landau Levels in a Carbon Nanotube.
DTSTART;VALUE=DATE-TIME:20110713T120000Z
DTEND;VALUE=DATE-TIME:20110713T121500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-4935@events.saip.org.za
DESCRIPTION:Speakers: Nanette Brand (Stellenbosch University)\nThe spectru
m of a carbon nanotube in a strong enough magnetic field (>50T for a 3nm n
anotube) revealed an almost dispersionless band at the Fermi energy. The f
ormation of Landau levels has been theoretically and experimentally invest
igated. In experimental studies the existence of Landau levels is indirect
ly derived from longitudinal conductance measurements. We will show that a
more direct indication of Landau Levels in the system exists\, namely a q
uantized Hall effect. We present numerical results that show the applicati
on of an electric field along the length of the tube lead to a current cir
culating the circumference and\, furthermore\, that the conductance is exa
ctly e2/h. This is interesting because the magnetic flux averages to zero
around the tube’s circumference. This phenomenon could be explained in t
erms of the two-dimensional topological theory for the quantum Hall effect
even though this system is quasi-one dimensional.\n\nhttps://events.saip.
org.za/event/7/contributions/4935/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/4935/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Physics of Exceptional Points
DTSTART;VALUE=DATE-TIME:20110715T103000Z
DTEND;VALUE=DATE-TIME:20110715T104500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5061@events.saip.org.za
DESCRIPTION:Speakers: W. Dieter Heiss (Dpt of Physics\, University Stellen
bosch)\nA short resume about the nature of EPs followed by a discussion ab
out their ubiquitous occurrence\nin a great variety of physical problems.
EPs feature in quantum phase transition\, quantum chaos\,\nthey produce dr
amatic effects in multichannel scattering\, specific time dependence and m
ore.\nIn nuclear physics they are associated with instabilities and affect
approximation schemes.\nEPs could be of interest for weakly bound states
such as halos and nuclei along the drip line.\n\nhttps://events.saip.org.z
a/event/7/contributions/5061/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5061/
END:VEVENT
BEGIN:VEVENT
SUMMARY:B3-B1 phase transition in GaAs: A Quantum Monte Carlo Study
DTSTART;VALUE=DATE-TIME:20110713T093000Z
DTEND;VALUE=DATE-TIME:20110713T094500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-4946@events.saip.org.za
DESCRIPTION:Speakers: Cecil Ouma (Student)\nThe pressure induced B3-B1 pha
se transition has been studied using both density functional theory (DFT)
and quantum Monte Carlo (QMC) methods. We present results obtained using
the local density approximation (LDA)\, PW91-GGA generalized gradient appr
oximation\, hybrid density functionals and QMC. The changes in the equatio
n of state has also been investigated using the different functionals and
form the results obtained\, we find that the choice of functional signific
antly effect the to the equation of state. The results of the B3-B1 phase
transition pressure for DFT using the different functionals and QMC are re
ported and they demonstrate good agreement with experimental data.\n\nhttp
s://events.saip.org.za/event/7/contributions/4946/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/4946/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Finite Element Calculations for Molecules with multiple Coulomb Ce
nters
DTSTART;VALUE=DATE-TIME:20110715T070000Z
DTEND;VALUE=DATE-TIME:20110715T073000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-4978@events.saip.org.za
DESCRIPTION:Speakers: Moritz Braun (University of South Africa)\nEfficient
and reliable methods to solve effective three dimensional Schroedinger e
quations are an important ingredient for both density functional as well
as Hartree Fock methods used to calculate the properties of molecules and
solids. In order to judge the accuracy of popular methods such as using G
aussian basis functions or smooth pseudo potentials it is desirable to use
a method that promises to be less basis dependent. \nSuch a method is the
finite element method\, where the convergence of the wave functions and e
igen values can be systemically improved. In combination with using a prod
uct ansatz of a function f(r) satisfying the cusp conditions at all nucl
ei and a smooth function phi(r) for the wave function this provides a meth
od to calculate all electron wave functions. The efficiency of this appro
ach in practice depends crucially on finding a finite element grid which p
rovides enough points where needed but does not “waste “ points where
not required. In this contribution results obtained for simple molecules v
ia two and three dimensional calculations are given.In addition the fin
ite element calculations are discussed in some detail.\n\nhttps://events.s
aip.org.za/event/7/contributions/4978/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/4978/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Density-matrix renormalization group study of the electro-absorpti
on in conjugated polymers
DTSTART;VALUE=DATE-TIME:20110713T090000Z
DTEND;VALUE=DATE-TIME:20110713T091500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-4981@events.saip.org.za
DESCRIPTION:Speakers: Anas Abdelwahab (Sudan University of Science and Tec
hnology)\nA symmetrized and dynamical density matrix renormalization group
is used to study 1-dimensional extended Peierls-Hubbard model at half-fil
ling. We have investigated the optical conductivity spectrum and electro-a
bsorption spectrum for low-lying optical exciton with strong\, intermediat
e and weak coupling parameter sets for the on-site and neighbor interactio
ns. We were able to capture the Stark effect in the case of strong couplin
g under static electric field. The intermediate coupling was found to be c
lear for weak electric field and destroyed for strong one. We were not abl
e to resolve the splitting in the case of weak coupling due to the small b
inding energy so that small value of electric field could distroy the exci
ton.\n\nhttps://events.saip.org.za/event/7/contributions/4981/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/4981/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Algebraic density functionals
DTSTART;VALUE=DATE-TIME:20110715T094500Z
DTEND;VALUE=DATE-TIME:20110715T101500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-4982@events.saip.org.za
DESCRIPTION:Speakers: Steven Karataglidis (University of Johannesburg)\nA
systematic strategy for the algebraic calculation of density functionals c
onsists in coding information about the density and the energy into polyno
mials of the degrees of freedom of the wave functions. Density functionals
and Kohn-Sham potentials are then obtained by standard elimination proced
ures of such degrees of freedom between the polynomials. Numerical example
s illustrate the formalism.\n\nhttps://events.saip.org.za/event/7/contribu
tions/4982/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/4982/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Giant Graviton Oscillator
DTSTART;VALUE=DATE-TIME:20110714T070000Z
DTEND;VALUE=DATE-TIME:20110714T073000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5000@events.saip.org.za
DESCRIPTION:Speakers: Robert de Mello Koch (University of the Witwatersran
d)\nN=4 SYM theory has been extensively studied in the planar limit. An im
portant result is that the planar dilatation operator can be mapped to the
Hamiltonian of an integrable system.\n\nIn this talk we study certain lar
ge N (but not planar) limits of the theory. We argue that the dilatation o
perator remains\nintegrable: it reduces to a set of decoupled harmonic osc
illators. This challenges claims that integrability is spoiled by non-plan
ar corrections.\n\nWe argue that the decoupled oscillators that arise desc
ribe the vibration modes of a quantum membrane.\n\nhttps://events.saip.org
.za/event/7/contributions/5000/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5000/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Many-boson Quantum Walks on Graphs with Shared Coins
DTSTART;VALUE=DATE-TIME:20110713T103000Z
DTEND;VALUE=DATE-TIME:20110713T104500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5024@events.saip.org.za
DESCRIPTION:Speakers: Dibwe Pierrot Musumbu (University of KwaZulu-Natal)\
nQuantum walks of particles obeying bose statistics are introduced. In suc
h a quantum walks the conditional\nshift operation is performed with the s
ingle coin tossing for the whole lattice. An explicit form for the transit
ion\nprobabilities in a single step is derived. This allow to describe the
evolution of an arbitrary state and an arbitrary\nnumber of steps. This m
odel easily embrace the concepts such as the join probability\, the counti
ng statistics and\nthe high order correlations. It also presents the compu
tational challenges arising from the exponential increase in the\nnumber o
f basis states entering into the lattice state as a function of the number
quantum walkers and the number of\nsteps. Possible solutions are proposed
in some applications of the model to quantum walks on finite graphs.\n\nh
ttps://events.saip.org.za/event/7/contributions/5024/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5024/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Wave-packet scattering off a soliton
DTSTART;VALUE=DATE-TIME:20110713T101500Z
DTEND;VALUE=DATE-TIME:20110713T103000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5025@events.saip.org.za
DESCRIPTION:Speakers: Ahmed Abdelhady (Stellenbosch University)\nWe invest
igate the scattering of a wave-packet off a soliton in the (1+1) dimension
al kink model. We solve the classical\, time-dependent field equation num
erically subject to the initial condition that the wave-packet is widely
separated from the kink soliton at very early times and propagates towards
the soliton. After some time the wave-packet interacts with the static so
liton and departs from it at later times. At very late times the wave-pack
et is finally again separated from the soliton. We then extract the scatte
ring matrix from the distorted wave-packet and compare it to the known res
ult from the static scattering calculation. This investigation constitutes
a first step towards studying crossing symmetry in soliton models\, i.e.
in a framework beyond perturbation theory.\n\nhttps://events.saip.org.za/e
vent/7/contributions/5025/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5025/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Towards the unconditional security proof for the Coherent-One-Way
(COW) protocol
DTSTART;VALUE=DATE-TIME:20110713T130000Z
DTEND;VALUE=DATE-TIME:20110713T131500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5016@events.saip.org.za
DESCRIPTION:Speakers: Mhlambululi Mafu (Centre for Quantum Technology)\nQu
antum Cryptography\, one aspect of which is Quantum Key Distri-\nbution (Q
KD)\, provides the only physically secure and proven method\nfor the trans
mission of a secret key between two distant parties\, Alice and Bob. The g
oal of QKD is to guarantee that a possible eavesdropper (Eve)\, with acces
s to the communication channel is unable to obtain useful information abou
t the message.\n\nThe Coherent-One-Way (COW) protocol is one of the most r
ecent practical QKD protocols. However\, its security proof still remains
unrealized. We therefore present a necessary condition for the security of
the COW protocol. In the proof\, we describe bob's measurements by non-co
mmuting POVM elements which satisfies this proof.\n\nhttps://events.saip.o
rg.za/event/7/contributions/5016/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5016/
END:VEVENT
BEGIN:VEVENT
SUMMARY:South African e-Infrastructure for physics applications
DTSTART;VALUE=DATE-TIME:20110714T121500Z
DTEND;VALUE=DATE-TIME:20110714T123000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5019@events.saip.org.za
DESCRIPTION:Speakers: Sean Murray (iThemba LABS)\nPhysics is one of the mo
st digitally-intensive areas of modern research and has traditionally led
the development of tools to increase the efficiency and capability of rese
arch activities. The integration of the tools necessary for today's compet
itive physics research projects\, from HPC centres to data resources\, met
adata catalogues\, and services to enable collaboration in virtual organis
ations has been done to a great extent in South Africa through the activit
ies of the South African National Grid (SAGrid). By forming a collaboratio
n to integrate their various computing facilities through the deployment o
f a common middleware\, the members of the SAGrid Joint Research Unit prov
ide many research communities with an integrated services infrastructure f
or collaboration. \nWe will give an overview of the grid in South Africa a
nd how it is connected to other regional infrastructure in Europe\, North
Africa\, Latin America and the U.S. We will show how it has enabled the So
uth African physicsists working on LHC experiments at CERN (ATLAS and ALIC
E) to conduct their work irrespective of their location. We will also show
some examples of how the grid has enabled collaborative research in areas
of physics\, and what application porting and user training services are
at the disposal of the general research communities. Advanced aspects of t
he grid middleware\, such as data management\, workflow\, and usage of met
adata catalogues will also be presented.\n\nhttps://events.saip.org.za/eve
nt/7/contributions/5019/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5019/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Designing reservoirs for 1/t decoherence process in Jaynes-Cummin
gs model
DTSTART;VALUE=DATE-TIME:20110714T091500Z
DTEND;VALUE=DATE-TIME:20110714T093000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5028@events.saip.org.za
DESCRIPTION:Speakers: Filippo Giraldi (University of KwaZulu-Natal)\nDecoh
erence indicates the process that a quantum system undergoes through th
e interaction with an external environment.\nThe central issue and one of
the greatest challenges in Nanotechnology and Quantum Information Processi
ng is the way to control or delay the destructive effect of the environmen
t on qubit coherence. For this reason\, a qubit interacting with a reservo
ir of bosons (external environment)\, described by a Jaynes-Cummings model
\, is considered. The decoherence process corresponding to Lorentzian type
distributions of field modes results in exponential like relaxations. At
this stage we adopt the engineering reservoir approach as the way of delay
ing the decoherence process. \nA special class of reservoirs of field mode
s is designed in order to obtain a decoherence process resulting\, over es
timated long time scales\, in inverse power laws with powers decreasing co
ntinuously to unity according to the choice of the particular reservoir. \
nThe designed reservoirs exhibit a photonic band gap coinciding with the q
ubit transition frequency and are piecewise similar to those usually adopt
ed in Quantum Optics\, i.e.\, sub-ohmic at low frequencies and inverse pow
er laws at high frequencies. Initially\, the reservoir is assumed to be in
the vacuum state and is unentangled from the qubit versing in a generic s
tate. The exact dynamics results to be described by series of Fox $H$-func
tions. The simple form of the designed reservoir can be accessible experim
entally.\n\nhttps://events.saip.org.za/event/7/contributions/5028/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5028/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Derivation of the master equation for a particle in an external fi
eld which is subject to continuous measurement.
DTSTART;VALUE=DATE-TIME:20110713T100000Z
DTEND;VALUE=DATE-TIME:20110713T101500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5029@events.saip.org.za
DESCRIPTION:Speakers: Kevin Garapo (Centre for Quantum Technology\, Univer
sity of Kwazulu-Natal.)\nThe theory of continuous measurement provides a t
ool to monitor the evolution of the wave function of a single quantum syst
em in real time. We derive the master equation in the non-selective regime
for the dynamics of the wave function of a particle in an external potent
ial which is subject to continuous measurement of position. In the derivat
ion we view continuous measurement as the limit of a sequence of unsharp
position measurements. Unsharp position measurements are described by gen
eralised measurement observables\, or in mathematical terms\, positive ope
rator valued measures (POVM) rather than the standard von Neumann projecti
on operators which are a special class of the sub-class of POVM's called p
rojection valued measures (PVM). We discuss a method which introduces a co
mmutative algebra for non-commuting operators in order to carry out the su
mmation of the corresponding measurement operators. In addition we reveal
the stochastic Ito equations for the selective regime of measurement.\n\nh
ttps://events.saip.org.za/event/7/contributions/5029/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5029/
END:VEVENT
BEGIN:VEVENT
SUMMARY:A comparison of purification schemes for treating the idempotency
condition on the density matrix in electronic structure calculations
DTSTART;VALUE=DATE-TIME:20110714T114500Z
DTEND;VALUE=DATE-TIME:20110714T121500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5040@events.saip.org.za
DESCRIPTION:Speakers: Matthiam Hoffman (UFS)\nDuring the last 15 years the
re has been considerable interest in density matrix based methods for elec
tronic structure calculations. The “difficult” problem of ensuring ide
mpotency conservation of the density matrix through an appropriate purific
ation scheme as well as the use of the “nearsightedness” and associate
d sparsity of the density matrix to achieve linear scaling with system siz
e has been discussed by various authors. \n\nIn this study a density matri
x based fictitious electron dynamics method for calculating electronic str
ucture is used in a model nanoparticle calculation. This method uses an eq
uation of motion that implicitly ensures the idempotency constraint on the
density matrix. The effectiveness of this method compared to conventional
purification schemes is discussed. \n\nImportant properties of the densit
y matrix and its sub matrices\, including its sparsity and conditions for
effective linear independence of a column sub matrix of the density matrix
are discussed and illustrated within the context of this model system. It
is shown how the full density matrix can be reconstructed through a fast
QR factorization of a column sub matrix using a Choleski factorization of
its principal sub matrix.\n\nhttps://events.saip.org.za/event/7/contributi
ons/5040/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5040/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Decoherence-assisted transport in a dimer system
DTSTART;VALUE=DATE-TIME:20110714T093000Z
DTEND;VALUE=DATE-TIME:20110714T094500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5075@events.saip.org.za
DESCRIPTION:Speakers: Ilya Sinayskiy (UKZN and NiTheP)\nThe transfer of en
ergy and information in quantum networks plays an important role in both q
uantum communication and quantum computation. The quantum system inevitabl
y interacts with the surrounding environment\, and such interaction leads
to dissipation and decoherence\, which are processes typically associated
with a destruction of quantum coherence in the system. However\, recently
evidence of surprisingly long-lived quantum coherence has been identified
in conjugate polymers and in photosynthetic light harvesting complexes. \n
\nHere\, the dynamics of a dimer under the influence of decoherence are st
udied. An exact analytical expression for the transition probability in th
e dimer system is obtained for different situations\, i.e.\, for the dimer
coupled to two independent environments\, and coupled to two correlated e
nvironments\, both in a spin star configuration. In all cases considered\,
it is shown that there exist well-defined ranges of parameters for which
decoherent interaction with the environment assists energy transfer in the
dimer system. In particular\, it is found that correlated environments ca
n assist energy transfer more efficiently than separate baths. \n\nThis si
mple and analytically solvable model for energy transfer in a dimer system
is easily extendible to more complex quantum networks\, and more complex
environmental models.\n\nhttps://events.saip.org.za/event/7/contributions/
5075/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5075/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Bilinear expansion of the photon quantum field and the emergence o
f classical mechanics from quantum field theory
DTSTART;VALUE=DATE-TIME:20110715T060000Z
DTEND;VALUE=DATE-TIME:20110715T063000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5084@events.saip.org.za
DESCRIPTION:Speakers: Jan Greben (CSIR)\nThe electro-magnetic field is exp
anded in a bilinear series consisting of products of quark creation and an
nihilation operators. This bilinear form is suggested by the equations of
motion for the electromagnetic field and provides a very powerful quantum
representation\, which is devoid of many of the technical problems associa
ted with standard quantization. In this approach the energy of the physica
l photon can be expressed as an expectation value of the energy-momentum t
ensor. The direct term already yields the correct result\, so one has to e
liminate the additional cross term to maintain this correct result. In ord
er to affect this elimination one needs to introduce a continuous set of
“hidden” quantum numbers\, which can be related to the classical posit
ional coordinate of the particle. These “big bang variables” are intro
duced as state labels\, just like the momentum variable. The quantum ampli
tudes are insensitive to the choice of these coordinates\, so that the int
roduction of classical coordinates does not conflict with standard quantum
field theory calculations or with the Heisenberg uncertainty principle. H
owever\, in a many-body system coherence make these coordinates emerge as
the relative classical coordinates. Hence\, classical mechanics emerges na
turally from many-body quantum field theory. Without violating quantum mec
hanics\, particles can thus be specified in terms of momentum and position
\, in clear analogy to classical physics and statistical mechanics. Compos
ite particle systems are then identified by having identical classical coo
rdinate labels\, while independent particles have distinct labels and are
not subject to the Pauli principle in the remaining variables.\n\nhttps://
events.saip.org.za/event/7/contributions/5084/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5084/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Enhancing the understanding of entropy through computation
DTSTART;VALUE=DATE-TIME:20110715T090000Z
DTEND;VALUE=DATE-TIME:20110715T091500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5093@events.saip.org.za
DESCRIPTION:Speakers: Trisha Salagaram (University of Pretoria)\nWe devise
a hierarchy of computational algorithms to enumerate the microstates of a
system comprising N independent\, distinguishable particles. An important
challenge is to cope with integers that increase exponentially with syste
m size\, and which very quickly become too large to be addressed by the co
mputer. A related problem is that the computational time for the most obvi
ous brute-force method scales exponentially with the system size which mak
es it difficult to study the system in the large N limit. Our methods addr
ess these issues in a systematic and hierarchical manner. We apply our met
hods to a simple model with single particle energy spectrum given by ε(p
\, q) = ε0 (p2 + q 4 )\, where p and q are non-negative integers. However
\, our methods are very general and applicable to a wide class of problems
. Working within the microcanonical\nensemble\, our methods enable one to
directly monitor the approach to the thermodynamic limit (N → ∞)\, and
in so doing\, the equivalence with the canonical ensemble is made more ma
nifest. Various thermodynamic quantities as a function of N may be compute
d using our methods\; in this paper\, we focus on the entropy\, the chemic
al potential and the temperature.\n\nhttps://events.saip.org.za/event/7/co
ntributions/5093/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5093/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Structure of Few-Hyperon Systems Studied with the Integro-Differen
tial Equations Approach
DTSTART;VALUE=DATE-TIME:20110713T131500Z
DTEND;VALUE=DATE-TIME:20110713T133000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5121@events.saip.org.za
DESCRIPTION:Speakers: John S. Nkuna (University of South Africa)\nGround-s
tate properties of three-nucleon systems consisting of one \nand two hyper
ons are studied with the integro-differential equations approach. The Hami
ltonian of the systems is constructed with semi-realistic nucleon-nucleon
interactions and phenomenological nucleon-hyperon interactions. The result
s obtained for the ground-state energies and root-mean-square radii are co
mpared with the findings of other theoretical methods.\n\nhttps://events.s
aip.org.za/event/7/contributions/5121/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5121/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Electromagnetic Form Factors of Three-Nucleon Systems
DTSTART;VALUE=DATE-TIME:20110714T103000Z
DTEND;VALUE=DATE-TIME:20110714T104500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5115@events.saip.org.za
DESCRIPTION:Speakers: Gaotsiwe Joel Rampho (University of South Africa)\nT
he angular-momentum-projected and parity-projected \nantisymmetrized molec
ular dynamics is used to analyse the charge and magnetic form factors of t
he three-nucleon systems. Non-relativistic nuclear charge and current oper
ators with relativistic corrections are employed. The Hamiltonian of the n
uclear systems is described with a semi-realistic nucleon-nucleon potentia
l. The results obtained are compared with results obtained using other the
oretical methods as well as some experimental data.\n\nhttps://events.saip
.org.za/event/7/contributions/5115/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5115/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Structure of Few-Nucleon Systems Studied with the Extended Antisym
metrized Molecular Dynamics
DTSTART;VALUE=DATE-TIME:20110714T101500Z
DTEND;VALUE=DATE-TIME:20110714T103000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5116@events.saip.org.za
DESCRIPTION:Speakers: Gaotsiwe Joel Rampho (University of South Africa)\nG
round-state properties of three-nucleon and four-nucleon systems \nare stu
died with the angular-momentum-projected and parity-projected antisymmetri
zed molecular dynamics. The Hamiltonian of the systems is constructed with
semi-realistic nucleon-nucleon interactions. The results obtained for the
ground-state energies\, root-mean-square radii and magnetic dipole moment
s are compared with the findings of other theoretical methods.\n\nhttps://
events.saip.org.za/event/7/contributions/5116/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5116/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Black-Hole Decay and Detection at LHC
DTSTART;VALUE=DATE-TIME:20110714T060000Z
DTEND;VALUE=DATE-TIME:20110714T061500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5120@events.saip.org.za
DESCRIPTION:Speakers: Warren Carlson (University of the Witwatersrand)\nMo
dels with extra spacial dimensions offer a new way to address outstanding
problems in and beyond the standard model. In such models the Planck scal
e in the bulk can be of the order of the electro-weak symmetry breaking sc
ale. This allows the coupling strength of gravity to increase to a size si
milar to the other interactions\, opening the way to the unification of gr
avity and the gauge interactions. The increased strength of gravity in the
bulk space-time means quantum gravity effects would be observable in the
TeV energy range - an energy range now attainable in modern particle colli
ders. If the Planck scale is low enough\, black-holes could form during co
llisions at particle colliders. These black-holes will emit radiation\, l
osing mass\, energy\, momentum\, etc. This radiation should be detectable
making it\, possible to "see" black-holes in particle colliders.\n\nhttps
://events.saip.org.za/event/7/contributions/5120/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5120/
END:VEVENT
BEGIN:VEVENT
SUMMARY:From few-body to many-body problems
DTSTART;VALUE=DATE-TIME:20110715T063000Z
DTEND;VALUE=DATE-TIME:20110715T064500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5128@events.saip.org.za
DESCRIPTION:Speakers: Mantile Lekala (UNISA)\nProblems involving bound sta
tes of few particles can be solved exactly since the number of degrees of
freedom are small. Several methods in this direction exist. One of these i
s the Integro-differential equation approximation method (IDEA). These few
-body methods have been succesfully applied to obtained bound and scatteri
ng states for three- and four-body problems for nuclear and molecular syst
ems. \n\nOn the other hand\, calculating observables for many-body systems
\, such as Bose-Einstein condensates\, is quite involved. Approximations a
t different levels\, i.e. formalism and numerical\, are necessary. In this
work we show that the IDEA method can be extended to many-body systems vi
a the transformation of the kernel\, and this transformation accelerate co
nvergence quite dramatically. Examples of molecular systems consisting of
particles upto 1000 atoms are handled quite easily. Technical aspects of t
he method are discussed.\n\nhttps://events.saip.org.za/event/7/contributio
ns/5128/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5128/
END:VEVENT
BEGIN:VEVENT
SUMMARY:One-way Quantum Computing with Photonic Orbital Angular Momentum
DTSTART;VALUE=DATE-TIME:20110713T124500Z
DTEND;VALUE=DATE-TIME:20110713T130000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5129@events.saip.org.za
DESCRIPTION:Speakers: Humairah Bassa (UKZN)\nOne-Way Quantum computing is
based on the preparation of certain entangled states of several particles\
, which are subsequently individually measured. The measurements serve to
process information as well as to read out the final result of the computa
tion. The implementation with OAM carrying \nphotons is based on the usa
ge of qubits (only two OAM values are relevant) but is a first step toward
s the implementation of a generalized form of One-Way Quantum computing
by means of qudits (involving more then two OAM values).\n\nhttps://events
.saip.org.za/event/7/contributions/5129/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5129/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Spectral method for studying nuclear four-body reactions
DTSTART;VALUE=DATE-TIME:20110713T123000Z
DTEND;VALUE=DATE-TIME:20110713T124500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5133@events.saip.org.za
DESCRIPTION:Speakers: Dithlase Masita (UNISA)\nReactions involving four pa
rticles\, either in the entrance or final channel\, are quite involved whe
n computing observables in comparison to three-body reactions. Yet these r
eactions are of interest in studying reactions of astrophysical interest\,
such as hep process\, which is essential for describing the quantitative
solar model. \n\nAt lower solar energies\, it is difficult to measure the
cross-section for the hep reaction. Moreover\, there are discrepancies in
calculations of the S-factor using different models and compared to the va
lue predicted by the Standard Solar model. This problem in turn implies pr
oblems in estimating the correct value for the reaction cross-section whic
h is crucial for the understanding of the Standard Solar model. In order t
o address this discrepancy and other observables\, a reliable numerical te
chnique is necessary. In this work we propose a new spectral method capabl
e of calculating low-energy phase shifts for scattering of the nucleon off
a light nucleus. We consider reactions of the type (3+1) --> (3+1)\, with
in the Faddeev-Yakubovsky framework. We show that these equations can be t
ransformed into spectral-type set of equations that are numerical less exp
ensive to solve in comparison to competing methods.\n\nhttps://events.saip
.org.za/event/7/contributions/5133/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5133/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Non-locality without inequality and generalized non-local theory
DTSTART;VALUE=DATE-TIME:20110714T100000Z
DTEND;VALUE=DATE-TIME:20110714T101500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5194@events.saip.org.za
DESCRIPTION:Speakers: Sujit Kumar Choudhary (University of KwaZulu-Natal)\
nWe find non-local but non-signaling probabilities satisfying the 'nonloca
lity without inequality’ arguments for multiple two-level systems. Maxim
um probability of success of these arguments are obtained in the framework
of a generalized nonlocal theory. Interestingly\, for two two-level syste
ms\, the probability of success of these arguments converge to a common ma
ximum\nin this framework. This is in sharp contrast with the quantum case\
, where for such systems\, Cabello’s argument succeeds more than that of
Hardy’s. We also find that the maximum probability of success of Hardy
’s argument is the same for both the two and three two-level systems in
the framework of this more generalized theory.\n\nhttps://events.saip.org.
za/event/7/contributions/5194/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5194/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Beyond the Planar Limit in ABJM Theory
DTSTART;VALUE=DATE-TIME:20110714T063000Z
DTEND;VALUE=DATE-TIME:20110714T064500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5179@events.saip.org.za
DESCRIPTION:Speakers: Badr Mohammed (PhD student at university of the Witw
atersrand)\nABJM theory is an N=6 Superconformal Chern-Simons theory with
gauge group U(N)XU(N). This gauge theory has been extensively studied in t
he planar limit. Motivated by similar results for N=4 SYM\, the planar dil
atation operator of ABJM theory has been mapped to the Hamiltonian of an i
ntegrable system.\n\nRecently\, it has been argued that there are large N
(but not planar) limits of N=4 SYM theory for which the dilatation operato
r remains integrable. Indeed\, it reduces to a set of decoupled harmonic o
scillators.\n\nMotivated by this result\, in this talk we study large N bu
t non-planar limits of the ABJM theory. This is accomplished by constructi
ng a complete set of gauge invariant operators for the theory. The free tw
o point functions of these operators is computed and the action of the dil
atation operator on these gauge invariant operators is constructed.\n\nhtt
ps://events.saip.org.za/event/7/contributions/5179/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5179/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Entanglement dynamics in an oscillating bipartite Gaussian state c
oupled to reservoirs with different temperatures
DTSTART;VALUE=DATE-TIME:20110714T090000Z
DTEND;VALUE=DATE-TIME:20110714T091500Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5184@events.saip.org.za
DESCRIPTION:Speakers: Anne Ghesquiere (National Institute for Theoretical
Physics)\nAn entangled bipartite Gaussian state is coupled to two thermal
reservoirs\, one for each particle. A harmonic oscillation is allowed betw
een the two particles. The reservoirs are assumed to have different temper
atures and to be coupled to the particles with different coupling strength
s. This allows for a realistic situation where a bipartite state may be sh
ared between two parties who ”keep” their part in different environmen
ts. A master equation\, previously derived in the non-rotating wave approx
imation\, is solved for the system. The effects of a variation in the bath
temperature on the entanglement\, as well as that of the variation in cou
pling strengths are shown. For high temperatures\, the entanglement vanish
es if the coupling strength is large\, whereas for low temperatures\, the
effect is reversed and it survives longest for a stronger coupling strengt
h. The stationary dynamics of the system is also examined.\n\nhttps://even
ts.saip.org.za/event/7/contributions/5184/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5184/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ferromagnetism in nuclear matter
DTSTART;VALUE=DATE-TIME:20110713T094500Z
DTEND;VALUE=DATE-TIME:20110713T100000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5228@events.saip.org.za
DESCRIPTION:Speakers: Jacobus Diener (Stellenbosch University)\nUnderstand
ing the magnetic effects of ultra-dense\, cold nuclear matter is of partic
ular importance when investigating the magnetic properties of dense matter
systems such as neutron stars. One property that we are interested in is
the possibility of generating a magnetic field in nuclear matter as the c
entral density increases. We investigate this possibility by employing a
relativistic\, self-consistent calculation to capture the interaction of t
he neutrons\, protons and electrons with the magnetic field. In this talk
we present this model for describing ferromagnetism in dense nuclear matt
er systems. Our current results will also be presented.\n\nhttps://events.
saip.org.za/event/7/contributions/5228/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5228/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Einstein - Eddington generalized gravity
DTSTART;VALUE=DATE-TIME:20110715T101500Z
DTEND;VALUE=DATE-TIME:20110715T103000Z
DTSTAMP;VALUE=DATE-TIME:20240624T064003Z
UID:indico-contribution-289-5233@events.saip.org.za
DESCRIPTION:Speakers: Evgeny Davydov (Joint Insitute for Nuclear Research)
\nThe present observational data strongly suggest that Einstein's gravity
must be modified\, one of the popular modifications being provided by supe
rstring ideas. In view of the mathematical problems of the string theory\,
other\, much simpler\, modifications of gravity that affect only the grav
itational sector (not touching other interactions) are also popular.\n\nOn
e of them is based on Einstein's idea to formulate the gravity theory in a
non-Riemannian space with a symmetric connection by use of a special vari
ational principle that allows one to determine the connection from a “ge
ometric” Lagrangian. This Lagrangian is assumed to depend on the general
ized Ricci curvature tensor and on other fundamental tensors and is varied
in the connection coefficients.\n\nWe discuss new models of this “affin
e” theory of gravity in multidimensional space-times with symmetric conn
ections. We use and generalize Einstein's proposal to specify the space-ti
me geometry by use of the Hamilton principle to determine the connection c
oefficients from a geometric Lagrangian that is an arbitrary function of t
he generalized Ricci curvature tensor and of other fundamental tensors. Su
ch a theory supplements the standard Einstein gravity with dark energy (th
e cosmological constant\, in the first approximation)\, a neutral massive
(or tachyonic) vector field (vecton)\, and massive (or tachyonic) scalar f
ields. These fields couple only to gravity and can generate dark matter an
d/or inflation. The concrete choice of the geometric Lagrangian determines
further details of the theory. The most natural geometric models look sim
ilar to recently proposed brane models of cosmology usually derived from s
tring theory.\n\nhttps://events.saip.org.za/event/7/contributions/5233/
LOCATION: Acro5
URL:https://events.saip.org.za/event/7/contributions/5233/
END:VEVENT
END:VCALENDAR