8,361 research outputs found
Characterization of the Vacuum Birefringence Polarimeter at BMV: Dynamical Cavity Mirror Birefringence
We present the current status and outlook of the optical characterization of
the polarimeter at the Bir\'{e}fringence Magn\'etique du Vide (BMV) experiment.
BMV is a polarimetric search for the QED predicted anisotropy of vacuum in the
presence of external electromagnetic fields. The main challenge faced in this
fundamental test is the measurement of polarization ellipticity on the order of
induced in linearly polarized laser field per pass through a
magnetic field having an amplitude and length
. This challenge is addressed by
understanding the noise sources in precision cavity-enhanced polarimetry. In
this paper we discuss the first investigation of dynamical birefringence in the
signal-enhancing cavity as a result of cavity mirror motion.Comment: To appear in the 2019 CPEM special issue of IEEE Transactions on
Instrumentation and Measuremen
Noise characterization for resonantly-enhanced polarimetric vacuum magnetic-birefringence experiments
In this work we present data characterizing the sensitivity of the
Bir\'{e}fringence Magnetique du Vide (BMV) instrument. BMV is an experiment
attempting to measure vacuum magnetic birefringence (VMB) via the measurement
of an ellipticity induced in a linearly polarized laser field propagating
through a birefringent region of vacuum in the presence of an external magnetic
field. Correlated measurements of laser noise alongside the measurement in the
main detection channel allow us to separate measured sensing noise from the
inherent birefringence noise of the apparatus. To this end we model different
sources of sensing noise for cavity-enhanced polarimetry experiments, such as
BMV. Our goal is to determine the main sources of noise, clarifying the
limiting factors of such an apparatus. We find our noise models are compatible
with the measured sensitivity of BMV. In this context we compare the phase
sensitivity of separate-arm interferometers to that of a polarimetry apparatus
for the discussion of current and future VMB measurements
Large Extra Dimensions at Linear Colliders
In this talk, I first present the motivation for theories wherein extra
spacetime dimensions can be compactified to have large magnitudes. In
particular, I discuss the Arkani-Hamed, Dimopoulos, Dvali (ADD) scenario. I
present the constraints that have been derived on these models from current
experiments and the expectations from future colliders. I concentrate
particularly on the possibilities of probing these extra dimensions at future
linear colliders.Comment: Talk given at the Third International Workshop on Electron-Electron
Interactions at TeV Energies (e- e- 99), Santa Cruz, California, 10-12 Dec
1999. 7 pages, LaTeX, style files attache
Voros product, noncommutative inspired Reissner-Nordstr{\"o}m black hole and corrected area law
We emphasize the importance of the Voros product in defining a noncommutative
inspired Reissner-Nordstr\"{o}m black hole. The entropy of this black hole is
then computed in the tunneling approach and is shown to obey the area law at
the next to leading order in the noncommutative parameter .
Modifications to entropy/area law is then obtained by going beyond the
semi-classical approximation. The leading correction to the semiclassical
entropy/area law is found to be logarithmic and its coefficient involves the
noncommutative parameter .Comment: 12 pages Late
Quantum Gravity Effects in Black Holes at the LHC
We study possible back-reaction and quantum gravity effects in the
evaporation of black holes which could be produced at the LHC through a
modification of the Hawking emission. The corrections are phenomenologically
taken into account by employing a modified relation between the black hole mass
and temperature. The usual assumption that black holes explode around TeV
is also released, and the evaporation process is extended to (possibly much)
smaller final masses. We show that these effects could be observable for black
holes produced with a relatively large mass and should therefore be taken into
account when simulating micro-black hole events for the experiments planned at
the LHC.Comment: 14 pages, 8 figures, extended version of hep-ph/0601243 with new
analysis of final products, final version accepted for publication in J.
Phys.
Single Production in Collisions at the NLC
Single production in collisions at the NLC can be used to
probe the Majorana nature of the heavy neutrinos present in the Left-Right
Symmetric Model below the kinematic threshold for their direct production. For
colliders in the TeV range, typical cross sections of order
are obtained, depending on the specific choice of model parameters.
Backgrounds arising from Standard Model processes are shown to be small. This
analysis greatly extends the kinematic range of previous studies wherein the
production of an on-shell, like-sign pair of 's at the NLC was considered.Comment: 13pp, 3 figures (available on request), LaTex, SLAC-PUB-647
Low Scale Non-universal, Non-anomalous U(1)'_F in a Minimal Supersymmetric Standard Model
We propose a non-universal U(1)'_F symmetry combined with the Minimal
Supersymmetric Standard Model. All anomaly cancellation conditions are
satisfied without exotic fields other than three right-handed neutrinos.
Because our model allows all three generations of chiral superfields to have
different U(1)'_F charges, upon the breaking of the U(1)'_F symmetry at a low
scale, realistic masses and mixing angles in both the quark and lepton sectors
are obtained. In our model, neutrinos are predicted to be Dirac fermions and
their mass ordering is of the inverted hierarchy type. The U(1)'_F charges of
the chiral super-fields also naturally suppress the mu term and automatically
forbid baryon number and lepton number violating operators. While all
flavor-changing neutral current constraints in the down quark and charged
lepton sectors can be satisfied, we find that constraint from D0-D0bar turns
out to be much more stringent than the constraints from the precision
electroweak data.Comment: 21 pages, 2 figures; v2: discussion on sparticle mass spectrum
included, 27 pages, 2 figure
Higgsless Electroweak Symmetry Breaking in Warped Backgrounds: Constraints and Signatures
We examine the phenomenology of a warped 5-dimensional model based on
SU(2) SU(2) U(1) model which implements
electroweak symmetry breaking through boundary conditions, without the presence
of a Higgs boson. We use precision electroweak data to constrain the general
parameter space of this model. Our analysis includes independent and
gauge couplings, radiatively induced UV boundary gauge kinetic terms, and all
higher order corrections from the curvature of the 5-d space. We show that this
setup can be brought into good agreement with the precision electroweak data
for typical values of the parameters. However, we find that the entire range of
model parameters leads to violation of perturbative unitarity in gauge boson
scattering and hence this model is not a reliable perturbative framework.
Assuming that unitarity can be restored in a modified version of this scenario,
we consider the collider signatures. It is found that new spin-1 states will be
observed at the LHC and measurement of their properties would identify this
model. However, the spin-2 graviton Kaluza-Klein resonances, which are a
hallmark of the Randall-Sundrum model, are too weakly coupled to be detected.Comment: More detailed analysis, added references, 43 pages, 15 figures, LaTe
t-channel production of heavy charged leptons
We study the pair production of heavy charged exotic leptons at e+ e-
colliders in the SU(2)_L x SU(2)_I x U(1)_Y model. This gauge group is a
subgroup of the grand unification group E6; SU(2)_I commutes with the electric
charge operator, and the three corresponding gauge bosons are electrically
neutral. In addition to the standard photon and Z boson contributions, we also
include the contributions from extra neutral gauge bosons. A t-channel
contribution due to W_I-boson exchange, which is unsuppressed by mixing angles,
is quite important. We calculate the left-right and forward-backward
asymmetries, and discuss how to differentiate different models.Comment: Increased discussion of experimental signatures. Version accepted by
PR
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