BEGIN:VCALENDAR
VERSION:2.0
PRODID:Baylor CMS Calendar /PHP/
METHOD:PUBLISH
BEGIN:VTIMEZONE
TZID:US_Central
BEGIN:STANDARD
DTSTART:20001029T020000
RRULE:FREQ=YEARLY;WKST=MO;INTERVAL=1;BYMONTH=11;BYDAY=1SU
TZNAME:Standard Time
TZOFFSETFROM:-0500
TZOFFSETTO:-0600
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:20010401T020000
RRULE:FREQ=YEARLY;WKST=MO;INTERVAL=1;BYMONTH=3;BYDAY=2SU
TZNAME:Daylight Saving Time
TZOFFSETFROM:-0600
TZOFFSETTO:-0500
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
UID:Baylor_CMS_Event-64478
DTSTAMP:20260609T115921Z
SUMMARY:CASPER Seminar: Jacob Moldenhauer, Graduate Student, UT Dallas, "Dynamic and Phenomenology of Higher Order Gravity Cosmological Models"
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:We present here some new results about a systematic approach to higher-order gravity (HOG)=0D=0A=
models. The HOG models are derived from curvature invariants that are more general than the=0D=0A=
Einstein-Hilbert action. Some of the models exhibit late-time cosmic acceleration without the need for=0D=0A=
dark energy and fit some current observations. The open question is that there are an infinite number of=0D=0A=
invariants that one could select, and many of the published papers have stressed the need to find a=0D=0A=
systematic approach that will allow one to study methodically the various possibilities. We explore a=0D=0A=
new connection that we made between theorems from the theory of invariants in general relativity and=0D=0A=
these cosmological models. In summary, the theorems demonstrate that curvature invariants are not all=0D=0A=
independent from each other and that for a given Ricci Segre type and Petrov type (symmetry=0D=0A=
classification) of the space-time, there exists a complete minimal set of independent invariants (a basis)=0D=0A=
in terms of which all the other invariants can be expressed. As an immediate consequence of the=0D=0A=
proposed approach, the number of invariants to consider is dramatically reduced from infinity to four=0D=0A=
invariants in the worst case and to only two invariants in the cases of interest, including all Friedmann-=0D=0A=
Lemaitre-Robertson-Walker metrics. We derive models that pass stability and physical acceptability=0D=0A=
conditions. We derive dynamical equations and phase portrait analyses that show the promise of the=0D=0A=
systematic approach. We consider observational constraints from magnitude-redshift Supernovae Type=0D=0A=
Ia data, distance to the last scattering surface of the Cosmic Microwave Background radiation, and=0D=0A=
Baryon Acoustic Oscillations. We seek to find models that pass physical and observational constraints=0D=0A=
and give fits to the data that are almost as good as those of the standard Lambda-Cold-Dark-Matter model.=0D=0A=
=0D=0A=
Jacob Moldenhauer is a graduate student in physics at the University of Texas at Dallas. He is a=0D=0A=
member of Dr. Mustapha Ishak's Relativity, Cosmology and Astrophysics group. Jacob is expecting to=0D=0A=
receive his Ph.D. in summer of 2010. His areas of research interest include the study of the cosmic=0D=0A=
acceleration, whether due to a cosmological constant, dark energy, or modification of gravity on large=0D=0A=
scales of distances. He is also interested in comparing cosmological models such as these to related=0D=0A=
observational probes for expansion history and growth of structure, such as supernovae, baryon=0D=0A=
acoustic oscillations, cosmic microwave background radiation, matter power spectrum, weak lensing,=0D=0A=
as well as local, solar system tests of gravity.=0D=0A=
=0D=0A=

LOCATION:BSB C206
DTSTART;TZID=US_Central:20100326T133000
DTEND;TZID=US_Central:20100326T143000
END:VEVENT
END:VCALENDAR