[Theory-seminars] Seminars next week

[Christopher Thomas]

Dear all,

Next week we have the following theory seminar (Carlos Schat) on Monday
and cake seminar (Liuming Liu) on Wednesday.

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Monday Dec 7th
1pm
L102/4

*Two new mass relations for L=1 excited baryons*

Carlos Schat
(Ohio University and Universidad de Buenos Aires)

I will discuss how a quark model can be matched to the more
systematic 1/Nc operator expansion for the masses of excited baryons.
Assuming the most general two-body quark-quark interactions
two new relations between the masses of L=1 baryons are found.
These relations correlate their mixing angles and can be used to
test for the presence of three-body forces.


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Wednesday Dec 9th
3pm
L102/4

*Singly and Doubly Charmed J=1/2 Baryon Spectrum from Lattice QCD*

Liuming Liu
(College of William & Mary)

We compute the masses of the singly and doubly charmed baryons in full
QCD using the relativistic Fermilab action for the charm quark. For the
light quarks we use domain-wall fermions in the valence sector and
improved Kogut-Susskind sea quarks. We use the low-lying charmonium
spectrum to tune our heavy-quark action and as a guide to understanding
the discretization errors associated with the heavy quark.

Our results are in good agreement with experiment within our
systematics.  For the Xi_{cc}, we find the isospin-averaged mass to be
M_{Xi_{cc}} = 3665 \pm 17 \pm 14 ^{+0}_{-78} MeV; the three given
uncertainties are statistical, systematic and an estimate of lattice
discretization errors, respectively.

In addition, we predict the mass splitting of the (isospin-averaged)
spin-1/2 Omega_{cc} with the Xi_{cc} to be M_{Omega_{cc}} - M_{Xi_{cc}}
= 98 \pm 9 \pm 22 \pm 13 MeV (in this mass splitting, the leading
discretization errors are also suppressed by SU(3) symmetry).

Combining this splitting with our determination of M_{Xi_{cc}} leads to
our prediction of the spin-1/2 Omega_{cc} mass, M_{Omega_{cc}} = 3763
\pm 19 \pm 26 ^{+13}_{-79} MeV.


Cake Sponsor: Kostas

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A complete list of upcoming theory seminars and talks from previous
seminars are available from:
http://www.jlab.org/~thomasc/seminars/index.html


Thanks,
Christopher

-- 
Christopher Thomas

Jefferson Laboratory
12000 Jefferson Avenue
Suite #1
Newport News
VA 23606
USA

Tel: +1 (757) 269 7453
Email: thomasc at jlab.org