1,778 research outputs found

### Taming the BFKL Intercept via Gluon Saturation

We show that the inclusion of parton density effects in the perturbative
small-x evolution reduces the strength of the powerlike growth of total
hadronic cross sections.Comment: 4 pages, 2 figures, Proceedings for Quark Matter 200

### Fermionic Operators from Bosonic Fields in 3+1 Dimensions

We present a construction of fermionic operators in 3+1 dimensions in terms
of bosonic fields in the framework of $QED_4$. The basic bosonic variables are
the electric fields $E_i$ and their conjugate momenta $A_i$. Our construction
generalizes the analogous constuction of fermionic operators in 2+1 dimensions.
Loosely speaking, a fermionic operator is represented as a product of an
operator that creates a pointlike charge and an operator that creates an
infinitesimal t'Hooft loop of half integer strength. We also show how the axial
$U(1)$ transformations are realized in this construction.Comment: 8 pages, two figures available on request, LA-UR-94-286

### No Froissart Bound from Gluon Saturation

In the previous work hep-ph/0112140, hep-ph/0204277, we showed that while the
nonlinear QCD evolution equation of Balitsky and Kovchegov (BK) leads to
saturation of the scattering amplitude locally in impact parameter space, it
does not unitarize the total cross section. This result was recently challenged
by Ferreiro, Iancu, Itakura and McLerran (FIIM) who claim that the
dipole-hadron cross section computed from the BK equation saturates the
Froissart bound. In this comment, we point to a fundamental error in the
argument of FIIM which invalidates their conclusion. We show that if the total
cross section violates unitarity for a coloured scattering probe, it does so
also for a colourless scattering probe.Comment: 5 pages LaTex, final version to be published in Phys. Lett. B, Note
added referring to recent controvers

### One gluon, two gluon: multigluon production via high energy evolution

We develop an approach for calculating the inclusive multigluon production
within the JIMWLK high energy evolution. We give a formal expression of
multigluon cross section in terms of a generating functional for arbitrary
number of gluons $n$. In the dipole limit the expression simplifies
dramatically. We recover the previously known results for single and double
gluon inclusive cross section and generalize those for arbitrary multigluon
amplitude in terms of Feynman diagramms of Pomeron - like objects coupled to
external rapidity dependent field $s(\eta)$. We confirm the conclusion that the
AGK cutting rules in general are violated in multigluon production. However we
present an argument to the effect that for doubly inclusive cross section the
AGK diagramms give the leading contribution at high energy, while genuine
violation only occurs for triple and higher inclusive gluon production. We
discuss some general properties of our expressions and suggest a line of
argument to simplify the approach further.Comment: 32 pages, one reference corrected. to appear in JHE

### BPS and non-BPS Domain Walls in Supersymmetric QCD with SU(3) Gauge Group

We study the spectrum of the domain walls interpolating between different
chirally asymmetric vacua in supersymmetric QCD with the SU(3) gauge group and
including 2 pairs of chiral matter multiplets in fundamental and
anti-fundamental representations. For small enough masses m < m* = .286... (in
the units of \Lambda), there are two different domain wall solutions which are
BPS-saturated and two types of ``wallsome sphalerons''. At m = m*, two BPS
branches join together and, in the interval m* < m < m** = 3.704..., BPS
equations have no solutions but there are solutions to the equations of motion
describing a non-BPS domain wall and a sphaleron. For m > m**, there are no
solutions whatsoever.Comment: 10 pages LaTeX, 5 postscript figure

### Bosonization in 2+1 dimensions without Chern - Simons attached

We perform the complete bosonization of 2+1 dimensional QED with one
fermionic flavor in the Hamiltonian formalism. The fermion operators are
explicitly constructed in terms of the vector potential and the electric field.
We carefully specify the regularization procedure involved in the definition of
these operators, and calculate the fermionic bilinears and the energy -
momentum tensor. The algebra of bilinears exhibits the Schwinger terms which
also appear in perturbation theory. The bosonic Hamiltonian density is a local
polynomial function of $A_i$ and $E_i$, and we check explicitly the Lorentz
invariance of the resulting bosonic theory. Our construction is conceptually
very similar to Mandelstam's construction in 1+1 dimensions, and is dissimilar
from the recent bosonization attempts in 2+1 dimensions which hinge crucially
on the existence of a Chern - Simons term.Comment: 12 pages, LA-UR-93-1062, some misprints and algebraic errors
corrected, several comments adde

### The Yin and Yang of High Energy Chromodynamics: Scattering in Black and White

We further discuss the QCD Reggeon field theory (RFT) as it emerges from the
JIMWLK/KLWMIJ evolution equation and beyond. We give an explicit expression for
the calculation of scattering amplitude in terms of the eigenstates of the RFT
Hamiltonian. We point out that the spectrum of RFT is doubly degenerate, the
degeneracy being related to the spontaneous breaking of the Dense-Dilute
Duality symmetry of RFT. The degeneracy is between the "almost white" states
(the Yang sector) which contain a small number of gluons, and "almost black"
states (the Yin sector). The excitations above the Yang vacuum have natural
interpretation in terms of gluons. Analogously the excitations above the Yin
vacuum have natural interpretation as "holes" in the black disk - points at
which an incoming gluon does not scatter with unit probability. We discuss in
detail the spectrum of the "parton model approximation" to the KLWMIJ evolution
introduced in our previous paper, and prove that it is explicitly selfdual.
This allows us to find explicitly the counterpart hole states in this
approximation. We also present an argument to the effect that the end point of
the evolution for any physical state cannot be a "grey disk" but must
necessarily be the "black disk" Yin vacuum state. Finally, we suggest an
approximation scheme for including the Pomeron loop contribution to the
evolution which requires only the solution of the JIMWLK/KLWMIJ Hamiltonian.Comment: 25 pages, 1 figur

### Eikonal but not: a complementary view of high energy evolution

The high energy evolution equations that describe the evolution of hadronic
amplitudes with energy are derived assuming eikonal interaction of the evolved
hadronic wave function with the target. In this note we remark that this
derivation allows a different interpretation, whereby the hadronic wave
function is not evolved, but instead the evolution acts on the S - matrix
operator. In this approach, analogous to the Heisenberg picture of Quantum
mechanics, the scattering is not eikonal and additional boost provides for
radiation of more gluons in the final state.Comment: 5 page

### SUSY 3D Georgi-Glashow model at finite temperature

We study the finite-temperature properties of the supersymmetric version of
(2+1)D Georgi-Glashow model. As opposed to its nonsupersymmetric counterpart,
the parity symmetry in this theory at zero temperature is spontaneously broken
by the bilinear photino condensate. We find that as the temperature is raised,
the deconfinement and the parity restoration occur in this model at the same
point $T_c=g^2/8\pi$. The transition is continuous, but is not of the Ising
type as in nonsupersymmetric Georgi-Glashow model, but rather of the
Berezinsky-Kosterlitz-Thouless type as in $Z_4$-invariant spin model.Comment: 8 pages, LaTeX2e, no figure

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