834 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
Energy from the gauge invariant observables
For a classical solution |Psi> in Witten's cubic string field theory, the
gauge invariant observable is conjectured to be equal to the
difference of the one-point functions of the closed string state corresponding
to V, between the trivial vacuum and the one described by |Psi>. For a static
solution |Psi>, if V is taken to be the graviton vertex operator with vanishing
momentum, the gauge invariant observable is expected to be proportional to the
energy of |Psi>. We prove this relation assuming that |Psi> satisfies equation
of motion and some regularity conditions. We discuss how this relation can be
applied to various solutions obtained recently.Comment: 27 pages; v5: minor revision in section 2, results unchange
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
On Gauge Equivalence of Tachyon Solutions in Cubic Neveu-Schwarz String Field Theory
Simple analytic solution to cubic Neveu-Schwarz String Field Theory including
the sector is presented. This solution is an analog of the
Erler-Schnabl solution for bosonic case and one of the authors solution for the
pure case. Gauge transformations of the new solution to others known
solutions for the string tachyon condensation are constructed explicitly.
This gauge equivalence manifestly supports the early observed fact that these
solutions have the same value of the action density.Comment: 8 pages, LaTe
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
The off-shell Veneziano amplitude in Schnabl gauge
We give a careful definition of the open string propagator in Schnabl gauge
and present its worldsheet interpretation. The propagator requires two
Schwinger parameters and contains the BRST operator. It builds surfaces by
gluing strips of variable width to the left and to the right of off-shell
states with contracted or expanded local frames. We evaluate explicitly the
four-point amplitude of off-shell tachyons. The computation involves a subtle
boundary term, crucial to enforce the correct exchange symmetries.
Interestingly, the familiar on-shell physics emerges even though string
diagrams produce Riemann surfaces more than once. Off-shell, the amplitudes do
not factorize over intermediate on-shell states.Comment: 48 pages, 10 figures. v2:acknowledgments 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 Prediction of Mass of Z'-Boson from Mixing
B_q^0-B_^0 bar mixing offers a profound probe into the effects of new
physics beyond the Standard Model. In this paper, and
mass differences are considered taking the effect of both
Z-and Z' -mediated flavour-changing neutral currents in the
mixing (q = d, s). Our estimated mass of Z' boson is accessible at the
experiments LHC and B-factories in near future.Comment: 11 pages, 02 Figure
Tachyon Vacuum in Cubic Superstring Field Theory
In this paper we give an exact analytic solution for tachyon condensation in
the modified (picture 0) cubic superstring field theory. We prove the absence
of cohomology and, crucially, reproduce the correct value for the D-brane
tension. The solution is surprising for two reasons: First, the existence of a
tachyon vacuum in this theory has not been definitively established in the
level expansion. Second, the solution {\it vanishes} in the GSO sector,
implying a ``tachyon vacuum'' solution exists even for a {\it BPS} D-brane.Comment: 16 pages, 2 figure
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
- …