33,824 research outputs found
The Gaugino Code
Gauginos might play a crucial role in the search for supersymmetry at the
Large Hadron Collider (LHC). Mass predictions for gauginos are rather robust
and often related to the values of the gauge couplings. We analyse the ratios
of gaugino masses in the LHC energy range for various schemes of supersymmetry
breakdown and mediation. Three distinct mass patterns emerge.Comment: 42 pages, Latex; a discussion of deflected anomaly mediation added,
references adde
Comment on "Can one predict DNA Transcription Start Sites by Studying Bubbles?"
Comment on T.S. van Erp, S. Cuesta-Lopez, J.-G. Hagmann, and M. Peyrard,
Phys. Rev. Lett. 95, 218104 (2005) [arXiv: physics/0508094]
Healing Length and Bubble Formation in DNA
We have recently suggested that the probability for the formation of
thermally activated DNA bubbles is, to a very good approximation, proportional
to the number of soft AT pairs over a length L(n) that depend on the size
of the bubble and on the temperature of the DNA. Here we clarify the physical
interpretation of this length by relating it to the (healing) length that is
required for the effect of a base-pair defect to become neligible. This
provides a simple criteria to calculate L(n) for bubbles of arbitrary size and
for any temperature of the DNA. We verify our findings by exact calculations of
the equilibrium statistical properties of the Peyrard-Bishop-Dauxois model. Our
method permits calculations of equilibrium thermal openings with several order
of magnitude less numerical expense as compared with direct evaluations
Supersymmetry Breaking and Moduli Stabilization with Anomalous U(1) Gauge Symmetry
We examine the effects of anomalous U(1)_A gauge symmetry on soft
supersymmetry breaking terms while incorporating the stabilization of the
modulus-axion multiplet responsible for the Green-Schwarz (GS) anomaly
cancellation mechanism. In case of the KKLT stabilization of the GS modulus,
soft terms are determined by the GS modulus mediation, the anomaly mediation
and the U(1)_A mediation which are generically comparable to each other,
thereby yielding the mirage mediation pattern of superparticle masses at low
energy scale. Independently of the mechanism of moduli stabilization and
supersymmetry breaking, the U(1)_A D-term potential can not be an uplifting
potential for de Sitter vacuum when the gravitino mass is smaller than the
Planck scale by many orders of magnitude. We also discuss some features of the
supersymmetry breaking by red-shifted anti-brane which is a key element of the
KKLT moduli stabilization.Comment: 32 pages; references are adde
Gaugino and Scalar Masses in the Landscape
In this letter we demonstrate the genericity of suppressed gaugino masses M_a
\sim m_{3/2}/ln(M_P/m_{3/2}) in the IIB string landscape, by showing that this
relation holds for D7-brane gauginos whenever the associated modulus is
stabilised by nonperturbative effects. Although m_{3/2} and M_a take many
different values across the landscape, the above small mass hierarchy is
maintained. We show that it is valid for models with an arbitrary number of
moduli and applies to both the KKLT and exponentially large volume approaches
to Kahler moduli stabilisation. In the latter case we explicitly calculate
gaugino and moduli masses for compactifications on the two-modulus Calabi-Yau
P^4_[1,1,1,6,9]. In the large-volume scenario we also show that soft scalar
masses are approximately universal with m_i^2 \sim m_{3/2}^2 (1 + \epsilon_i),
with the non-universality parametrised by \epsilon_i \sim 1/ln (M_P/m_{3/2})^2
\sim 1/1000. We briefly discuss possible phenomenological implications of our
results.Comment: 15 pages, JHEP style; v2. reference adde
CP violation in chargino production and decay into sneutrino
We study CP odd asymmetries in chargino production E+ E- --> ~Chi(+-)(1)
\~Chi(-+)(2) and the subsequent two-body decay of one chargino into a
sneutrino. We show that in the Minimal Supersymmetric Standard Model with
complex parameter \mu the asymmetries can reach 30 %. We discuss the
feasibility of measuring these asymmetries at a linear collider with \sqrt{s} =
800 GeV and longitudinally polarized beams.Comment: 10 pages, 3 figure
LHC Signature of Mirage Mediation
We study LHC phenomenology of mirage mediation scenario in which anomaly and
modulus contributions to soft SUSY breaking terms are comparable to each other.
A Monte Carlo study of mirage mediation, with model parameters , GeV, , and , is presented. It is
shown that masses of supersymmetric particles can be measured in a model
independent way, providing information on SUSY breaking sector. In particular,
the mass ratio of gluino to the lightest neutralino for the benchmark scenario
is determined to be 1.9 \lesssim m_{\tildeg}/m_{\tilde\chi_1^0} \lesssim 3.1,
well reproducing theoretical input value of which is quite distinctive from the predictions of other SUSY scenarios in which gaugino
masses are unified at the GUT scale. The model parameters of mirage mediation
can be also determined from various kinematic distributions
CP asymmetries in neutralino production in e+e- collisions
We study two CP sensitive triple-product asymmetries for neutralino
production e+e- \to\tilde\chi^0_i \tilde\chi^0_j and the subsequent leptonic
two-body decay \tilde\chi^0_i \to \tilde l l, \tilde l \to \tilde\chi^0_1 l,
for \l= e,\mu,\tau. We calculate the asymmetries, cross sections and branching
ratios in the Minimal Supersymmetric Standard Model with complex parameters \mu
and M_1. We present numerical results for the asymmetries to be expected at a
linear electron-positron collider in the 500 GeV range. The asymmetries can go
up to 25 %. We estimate the event rates which are necessary to observe the
asymmetries. Polarized electron and positron beams can significantly enhance
the asymmetries and cross sections. In addition, we show how the two decay
leptons can be distinguished by making use of their energy distributions.Comment: 22 pages, 7 figures; typos corrected, version to appear in Phys. Rev.
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