1,627 research outputs found
Another Odd Thing About Unparticle Physics
The peculiar propagator of scale invariant unparticles has phases that
produce unusual patterns of interference with standard model processes. We
illustrate some of these effects in .Comment: 9 pages, 8 figures - minor wording changes and additional reference
in v
- Mixing in Heavy Quark Effective Field Theory
I analyze -\ol D mixing using the techniques of heavy quark effect field
theory. The analysis suggests that the there may be important cancellations
among the dispersive effects of different kinds of final states, so that the
total mixing may be considerably smaller than previous estimates.Comment: 10 pages (big mode), #HUTP-92/A04
Generalized Dimensional Analysis
I describe a version of so-called naive dimensional analysis, a rule for
estimating the sizes of terms in an effective theory below the scale of chiral
symmetry breaking induced by a strong gauge interaction. The rule is simpler
and more general than the original, which it includes as a special case. I also
give a simple qualitative interpretation of the rule.Comment: 5 pages, LATE
Chiral Fermion Delocalization in Deconstructed Higgsless Theories
{I construct a renormalizable gauge theory with
standard-model-like phenomenology for the gauge bosons masses and the weak
interactions of the light fermions (including the ) but in which all vacuum
expectation values are about 2 TeV. This is a deconstructed version of a
Higgsless model with a flat extra dimension. The fermions are delocalized on
the theory space in an unusual way, with LH and RD fermions on alternate nodes.Comment: 12 pages, latex with pictex figure embedde
Physics Fun with Discrete Scale Invariance
I construct a quantum field theory model with discrete scale invariance at
tree level. The model has some unusual mathematical properties (such as the
appearance of -hypergeometric series) and may possibly have some interesting
physical properties as well. In this note, I explore some possible physics that
could be regarded as a violation of standard effective field theory ideas.Comment: 18 pages, 24 figure
A Simple Alternative to Jet-Clustering Algorithms
I describe a class of iterative jet algorithms that are based on maximizing a
fixed function of the total 4-momentum rather than clustering of pairs of jets.
I describe some of the properties of the simplest examples of this class,
appropriate for jets at an machine. These examples are sufficiently
simple that many features of the jets that they define can be determined
analytically with ease. The jets constructed in this way have some potentially
useful properties, including a strong form of infrared safety.Comment: 7 pages, 0 figure
Sidney Coleman's Harvard
A talk presented at the April 2016 APS meeting in Salt Lake City: The speaker
had the great good fortune to take an undergraduate course in group theory from
Sidney Coleman, and (after graduate school away) was hired by Coleman to a
postdoctoral position and eventually became a faculty colleague. He will share
some still vivid memories of this remarkable character.Comment: 21 page
The Schwinger Point
The Sommerfield model with a massive vector field coupled to a massless
fermion in 1+1 dimensions is an exactly solvable analog of a Bank-Zaks model.
The `physics' of the model comprises a massive boson and an unparticle sector
that survives at low energy as a conformal field theory (Thirring model). I
discuss the `Schwinger point' of the Sommerfield model in which the vector
boson mass goes to zero. The limit is singular but gauge invariant quantities
should be well-defined. I give a number of examples, both (trivially) with
local operators and with nonlocal products connected by Wilson lines (the
primary technical accomplishment in this note is the explicit and very
pedestrian calculation of correlators involving straight Wilson lines). I hope
that this may give some insight into the nature of bosonization in the
Schwinger model and its connection with unparticle physics which in this simple
case may be thought of as `incomplete bosonization.'Comment: 19 pages, 2 figures, new discussion of n-flavor Schwinger model -
version 3 minor changes to prepare for submissio
A Little Large N Group Theory
We discuss the group theory relevant to the ground-state baryons in large N_c
QCD. For very large representation, the group generators become classical
variables. We find the form of the classical generators for the completely
symmetric N index representation of as and derive
an integral formula for the matrix elements of an arbitrary polynomial in the
group generators between low-spin baryon states in the large N limit.Comment: 13 pages, LaTe
Diboson Excess from a New Strong Force
We explore a "partial unification" model that could explain the diphoton
event excess around recently reported by the LHC experiments.
A new strong gauge group is combined with the ordinary color and hypercharge
gauge groups. The VEV responsible for the combination is of the order of the
breaking scale, but the coupling of the new physics to
standard model particles is suppressed by the strong interaction of the new
gauge group. This simple extension of the standard model has a rich
phenomenology, including composite particles of the new confining gauge
interaction, a coloron and a which are rather weakly coupled to standard
model particles, and massive vector bosons charged under both the ordinary
color and hypercharge gauge groups and the new strong gauge group. The new
scalar glueball could have mass of around , be produced by
gluon fusion and decay into two photons, both through loops of the new massive
vector bosons. The simplest version of the model has some issues: the massive
vector bosons are stable and the coloron and the are strongly constrained
by search data. An extension of the model to include additional fermions with
the new gauge coupling, though not as simple and elegant, can address both
issues and more. It allows the massive vector boson to decay into a colorless,
neutral state that could be a candidate of the dark matter. And the coloron and
can decay dominantly into the new fermions, completely changing the search
bounds. In addition, fermions below the symmetry breaking scale make it
more plausible that the lightest glueball is at ~GeV. Whatever becomes of
the ~GeV diphoton excess, the model is an unusual example of how new
physics at small scales could be hidden by strong interactions.Comment: 33 pages, 4 figures, 7 table
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