44 research outputs found
On surface states and star-subalgebras in string field theory
We elaborate on the relations between surface states and squeezed states.
First, we investigate two different criteria for determining whether a matter
sector squeezed state is also a surface state and show that the two criteria
are equivalent. Then, we derive similar criteria for the ghost sector. Next, we
refine the criterion for determining whether a surface state is in
H_{\kappa^2}, the subalgebra of squeezed states obeying [S,K_1^2]=0. This
enables us to find all the surface states of the H_{\kappa^2} subalgebra, and
show that it consists only of wedge states and (hybrid) butterflies. Finally,
we investigate generalizations of this criterion and find an infinite family of
surface states subalgebras, whose surfaces are described using a "generalized
Schwarz-Christoffel" mapping.Comment: 38 pages, 6 figures, JHEP style; typos corrected, ref. adde
Identification of extra neutral gauge bosons at the International Linear Collider
Heavy neutral gauge bosons, Z's, are predicted by many theoretical schemes of
physics beyond the Standard Model, and intensive searches for their signatures
will be performed at present and future high energy colliders. It is quite
possible that Z's are heavy enough to lie beyond the discovery reach expected
at the CERN Large Hadron Collider LHC, in which case only indirect signatures
of Z' exchanges may occur at future colliders, through deviations of the
measured cross sections from the Standard Model predictions. We here discuss in
this context the foreseeable sensitivity to Z's of fermion-pair production
cross sections at an e^+e^- linear collider, especially as regards the
potential of distinguishing different Z' models once such deviations are
observed. Specifically, we assess the discovery and identification reaches on
Z' gauge bosons pertinent to the E_6, LR, ALR and SSM classes of models, that
should be attained at the planned International Linear Collider (ILC). With the
high experimental accuracies expected at the ILC, the discovery and the
identification reaches on the Z' models under consideration could be increased
substantially. In particular, the identification among the different models
could be achieved for values of Z' masses in the discovery (but beyond the
identification) reach of the LHC. An important role in enhancing such reaches
is played by the electron (and possibly the positron) longitudinally polarized
beams. Also, although the purely leptonic processes are experimentally cleaner,
the measurements of c- and b-quark pair production cross sections are found to
carry important, and complementary, information on these searches.Comment: 21 page
The Bethe Ansatz for Z_S Orbifolds of N=4 Super Yang-Mills Theory
Worldsheet techniques can be used to argue for the integrability of string
theory on AdS_5xS^5/Z_S, which is dual to the strongly coupled Z_S-orbifold of
N=4 SYM. We analyze the integrability of these field theories in the
perturbative regime and construct the relevant Bethe equations.Comment: 16 page
On the validity of the solution of string field theory
We analyze the realm of validity of the recently found tachyon solution of
cubic string field theory. We find that the equation of motion holds in a non
trivial way when this solution is contracted with itself. This calculation is
needed to conclude the proof of Sen's first conjecture. We also find that the
equation of motion holds when the tachyon or gauge solutions are contracted
among themselves.Comment: JHEP style, 9+1 pages. Typos correcte
Virasoro operators in the continuous basis of string field theory
In this work we derive two important tools for working in the \kappa basis of
string field theory. First we give an analytical expression for the finite part
of the spectral density \rho_{fin}. This expression is relevant when both
matter and ghost sectors are considered. Then we calculate the form of the
matter part of the Virasoro generators L_n in the \kappa basis, which construct
string field theory's derivation Q_{BRST}. We find that the Virasoro generators
are given by one dimensional delta functions with complex arguments.Comment: 16 page
Schnabl's L_0 Operator in the Continuous Basis
Following Schnabl's analytic solution to string field theory, we calculate
the operators for a scalar field in the
continuous basis. We find an explicit and simple expression for them
that further simplifies for their sum, which is block diagonal in this basis.
We generalize this result for the bosonized ghost sector, verify their
commutation relation and relate our expressions to wedge state representations.Comment: 1+16 pages. JHEP style. Typos correcte
Open Superstring Star as a Continuous Moyal Product
By diagonalizing the three-string vertex and using a special coordinate
representation the matter part of the open superstring star is identified with
the continuous Moyal product of functions of anti-commuting variables. We show
that in this representation the identity and sliver have simple expressions.
The relation with the half-string fermionic variables in continuous basis is
given.Comment: Latex, 19 pages; more comments added and notations are simplifie
On Continuous Moyal Product Structure in String Field Theory
We consider a diagonalization of Witten's star product for a ghost system of
arbitrary background charge and Grassmann parity. To this end we use a
bosonized formulation of such systems and a spectral analysis of Neumann
matrices. We further identify a continuous Moyal product structure for a
combined ghosts+matter system. The normalization of multiplication kernel is
discussed.Comment: 18+7 pages, 1 figure, typos correction
Universal Extra Dimensions and the Higgs Boson Mass
We study the combined constraints on the compactification scale 1/R and the
Higgs mass m_H in the standard model with one or two universal extra
dimensions. Focusing on precision measurements and employing the
Peskin-Takeuchi S and T parameters, we analyze the allowed region in the (m_H,
1/R) parameter space consistent with current experiments. For this purpose, we
calculate complete one-loop KK mode contributions to S, T, and U, and also
estimate the contributions from physics above the cutoff of the
higher-dimensional standard model. A compactification scale 1/R as low as 250
GeV and significantly extended regions of m_H are found to be consistent with
current precision data.Comment: 21 pages, Latex, 6 eps figures, an error in calculations was
corrected and results of analysis changed accordingly, references adde
Comments on Schnabl's analytic solution for tachyon condensation in Witten's open string field theory
Schnabl recently constructed an analytic solution for tachyon condensation in
Witten's open string field theory. The solution consists of two pieces. Only
the first piece is involved in proving that the solution satisfies the equation
of motion when contracted with any state in the Fock space. On the other hand,
both pieces contribute in evaluating the kinetic term to reproduce the value
predicted by Sen's conjecture. We therefore need to understand why the second
piece is necessary. We evaluate the cubic term of the string field theory
action for Schnabl's solution and use it to show that the second piece is
necessary for the equation of motion contracted with the solution itself to be
satisfied. We also present the solution in various forms including a pure-gauge
configuration and provide simpler proofs that it satisfies the equation of
motion.Comment: 33 pages, 4 figures, LaTeX2e; v2: minor changes, version published in
JHE