1,010 research outputs found
Generating Erler-Schnabl-type Solution for Tachyon Vacuum in Cubic Superstring Field Theory
We study a new set of identity-based solutions to analyze the problem of
tachyon condensation in open bosonic string field theory and cubic superstring
field theory. Even though these identity-based solutions seem to be trivial, it
turns out that after performing a suitable gauge transformation, we are left
with the known Erler-Schnabl-type solutions which correctly reproduce the value
of the D-brane tension. This result shows explicitly that how a seemingly
trivial solution can generate a non-trivial configuration which precisely
represents to the tachyon vacuum.Comment: 22 pages, references added, appendix added, 2 subsections adde
Regularization of identity based solution in string field theory
We demonstrate that an Erler-Schnabl type solution in cubic string field
theory can be naturally interpreted as a gauge invariant regularization of an
identity based solution. We consider a solution which interpolates between an
identity based solution and ordinary Erler-Schnabl one. Two gauge invariant
quantities, the classical action and the closed string tadpole, are evaluated
for finite value of the gauge parameter. It is explicitly checked that both of
them are independent of the gauge parameter.Comment: 9 pages, minor typos corrected and references adde
Comments on regularization of identity based solutions in string field theory
We analyze the consistency of the recently proposed regularization of an
identity based solution in open bosonic string field theory. We show that the
equation of motion is satisfied when it is contracted with the regularized
solution itself. Additionally, we propose a similar regularization of an
identity based solution in the modified cubic superstring field theory.Comment: 24 pages, two subsections added, two references adde
Relevant Deformations in Open String Field Theory: a Simple Solution for Lumps
We propose a remarkably simple solution of cubic open string field theory
which describes inhomogeneous tachyon condensation. The solution is in
one-to-one correspondence with the IR fixed point of the RG-flow generated in
the two--dimensional world-sheet theory by integrating a relevant operator with
mild enough OPE on the boundary. It is shown how the closed string overlap
correctly captures the shift in the closed string one point function between
the UV and the IR limits of the flow. Examples of lumps in non-compact and
compact transverse directions are given.Comment: 45 pages. v2: typos and minor improvements. v3: submitted to jhe
The Phantom Term in Open String Field Theory
We show that given any two classical solutions in open string field theory
and a singular gauge transformation relating them, it is possible to write the
second solution as a gauge transformation of the first plus a singular,
projector-like state which describes the shift in the open string background
between the two solutions. This is the "phantom term." We give some
applications in the computation of gauge invariant observables.Comment: V2: minor improvements, added citation
Boundary State from Ellwood Invariants
Boundary states are given by appropriate linear combinations of Ishibashi
states. Starting from any OSFT solution and assuming Ellwood conjecture we show
that every coefficient of such a linear combination is given by an Ellwood
invariant, computed in a slightly modified theory where it does not trivially
vanish by the on-shell condition. Unlike the previous construction of
Kiermaier, Okawa and Zwiebach, ours is linear in the string field, it is
manifestly gauge invariant and it is also suitable for solutions known only
numerically. The correct boundary state is readily reproduced in the case of
known analytic solutions and, as an example, we compute the energy momentum
tensor of the rolling tachyon from the generalized invariants of the
corresponding solution. We also compute the energy density profile of
Siegel-gauge multiple lump solutions and show that, as the level increases, it
correctly approaches a sum of delta functions. This provides a gauge invariant
way of computing the separations between the lower dimensional D-branes.Comment: v2: 63 pages, 14 figures. Major improvements in section 2. Version
published in JHE
The energy of the analytic lump solution in SFT
In a previous paper a method was proposed to find exact analytic solutions of
open string field theory describing lower dimensional lumps, by incorporating
in string field theory an exact renormalization group flow generated by a
relevant operator in a worldsheet CFT. In this paper we compute the energy of
one such solution, which is expected to represent a D24 brane. We show, both
numerically and analytically, that its value corresponds to the theoretically
expected one.Comment: 45 pages, former section 2 suppressed, Appendix D added, comments and
references added, typos corrected. Erratum adde
Z' Bosons at Colliders: a Bayesian Viewpoint
We revisit the CDF data on di-muon production to impose constraints on a
large class of Z' bosons occurring in a variety of E_6 GUT based models. We
analyze the dependence of these limits on various factors contributing to the
production cross-section, showing that currently systematic and theoretical
uncertainties play a relatively minor role. Driven by this observation, we
emphasize the use of the Bayesian statistical method, which allows us to
straightforwardly (i) vary the gauge coupling strength, g', of the underlying
U(1)'; (ii) include interference effects with the Z' amplitude (which are
especially important for large g'); (iii) smoothly vary the U(1)' charges; (iv)
combine these data with the electroweak precision constraints as well as with
other observables obtained from colliders such as LEP 2 and the LHC; and (v)
find preferred regions in parameter space once an excess is seen. We adopt this
method as a complementary approach for a couple of sample models and find
limits on the Z' mass, generally differing by only a few percent from the
corresponding CDF ones when we follow their approach. Another general result is
that the interference effects are quite relevant if one aims at discriminating
between models. Finally, the Bayesian approach frees us of any ad hoc
assumptions about the number of events needed to constitute a signal or
exclusion limit for various actual and hypothetical reference energies and
luminosities at the Tevatron and the LHC.Comment: PDFLaTeX, 24 pages, 7 figures. Version with improved tables and
figure
Constraints on a class of classical solutions in open string field theory
We calculate boundary states for general string fields in the KBc subalgebra
under some regularity conditions based on the construction by Kiermaier, Okawa,
and Zwiebach. The resulting boundary states are always proportional to that for
the perturbative vacuum |B>. In this framework, the equation of motion implies
that boundary states are independent of the auxiliary parameter s associated
with the length of the boundary. By requiring the s-independence, we show that
the boundary states for classical solutions in our class are restricted to
\pm|B> and 0. In particular, there exist no string fields which reproduce
boundary states for multiple D-brane backgrounds. While we know that the
boundary states |B> and 0 are reproduced by solutions for the perturbative
vacuum and the tachyon vacuum, respectively, no solutions reproducing -|B> have
been constructed. In this paper we also propose a candidate for such a
solution, which may describe the ghost D-brane.Comment: 47 pages, 3 figures; v2: appendix B is expande
Probing Z' gauge boson with the spin configuration of top quark pair production at future linear colliders
We explore the effects of extra neutral gauge boson involved in the
supersymmetric E6 model on the spin configuration of the top quark pair
produced at the polarized e- e+ collider. Generic mixing terms are considered
including kinetic mixing terms as well as mass mixing. In the off-diagonal spin
basis of the standard model, we show that the cross sections for the suppressed
spin configurations can be enhanced with the effects of the Z' boson through
the modification of the spin configuration of produced top quark pair enough to
be measured in the Linear Colliders, which provides the way to observe the
effects of Z' boson and discriminate the pattern of gauge group decomposition.
It is pointed out that the kinetic mixing may dilute the effects of mass mixing
terms, and we have to perform the combined analysis.Comment: 19 pages including 5 figures, ReVTe
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