80 research outputs found
Polarization mesurements of gamma ray bursts and axion like particles
A polarized gamma ray emission spread over a sufficiently wide energy band
from a strongly magnetized astrophysical object like gamma ray bursts (GRBs)
offers an opportunity to test the hypothesis of axion like particles (ALPs).
Based on evidences of polarized gamma ray emission detected in several gamma
ray bursts we estimated the level of ALPs induced dichroism, which could take
place in the magnetized fireball environment of a GRB. This allows to estimate
the sensitivity of polarization measurements of GRBs to the ALP-photon
coupling. This sensitivity \gag\le 2.2\cdot 10^{-11} {\rm GeV^{-1}}
calculated for the ALP mass and MeV energy spread of
gamma ray emission is competitive with the sensitivity of CAST and becomes even
stronger for lower ALPs masses.Comment: Contribution to Proc. 4th Patras Workshop on Axions, WIMPs and WISPs
(18-21 June 2008, DESY
Exploration of Possible Quantum Gravity Effects with Neutrinos I: Decoherence in Neutrino Oscillations Experiments
Quantum gravity may involve models with stochastic fluctuations of the
associated metric field, around some fixed background value. Such stochastic
models of gravity may induce decoherence for matter propagating in such
fluctuating space time. In most cases, this leads to fewer neutrinos of all
active flavours being detected in a long baseline experiment as compared to
three-flavour standard neutrino oscillations. We discuss the potential of the
CNGS and J-PARC beams in constraining models of quantum-gravity induced
decoherence using neutrino oscillations as a probe. We use as much as possible
model-independent parameterizations, even though they are motivated by specific
microscopic models, for fits to the expected experimental data which yield
bounds on quantum-gravity decoherence parameters.Comment: 9 pages, 4 figures, proceedings for invited talk by A.Sakharov at
DISCRETE'08, Valencia, Spain; December 200
Quantum-Gravity Decoherence Effects in Neutrino Oscillations: Expected Constraints from CNGS and J-PARC
Quantum decoherence, the evolution of pure states into mixed states, may be a
feature of quantum-gravity models. In most cases, such models lead to fewer
neutrinos of all active flavours being detected in a long baseline experiment
as compared to three-flavour standard neutrino oscillations. We discuss the
potential of the CNGS and J-PARC beams in constraining models of
quantum-gravity induced decoherence using neutrino oscillations as a probe. We
use as much as possible model-independent parameterizations, even though they
are motivated by specific microscopic models, for fits to the expected
experimental data which yield bounds on quantum-gravity decoherence parameters.Comment: 40 pages, 8 figures, minor correction
An incremental approach to unravel the neutrino mass hierarchy and CP violation with a long-baseline Superbeam for large
Recent data from long-baseline neutrino oscillation experiments have provided
new information on \theta_{13}, hinting that 0.01\lesssim sin^2 2\theta_{13}
\lesssim 0.1 at 2 sigma C.L. Confirmation of this result with high significance
will have a crucial impact on the optimization of the future long-baseline
oscillation experiments designed to probe the neutrino mass ordering and
leptonic CP violation. In this context, we expound in detail the physics reach
of an experimental setup where neutrinos produced in a conventional wide-band
beam facility at CERN are observed in a proposed Giant Liquid Argon detector at
the Pyh\"asalmi mine, at a distance of 2290 km. This particular setup would
have unprecedented sensitivity to the mass ordering and CP violation in the
light of large \theta_{13}. With a 10 to 20 kt `pilot' detector and just a few
years of neutrino beam running, the mass hierarchy could be determined,
irrespective of the true values of \delta_{CP} and the mass hierarchy, at 3
sigma (5 sigma) C.L. if sin^2 2\theta_{13}(true) = 0.05 (0.1). With the same
exposure, we start to have 3 sigma sensitivity to CP violation if sin^2
2\theta_{13}(true) > 0.05, in particular testing maximally CP-violating
scenarios at a high C.L. After optimizing the neutrino and anti-neutrino
running fractions, we study the performance of the setup as a function of the
exposure, identifying three milestones to have roughly 30%, 50% and 70%
coverage in \delta_{CP}(true) for 3 sigma CP violation discovery. For
comparison, we also study the CERN to Slanic baseline of 1540 km. This work
demonstrates that an incremental program, staged in terms of the exposure, can
achieve the desired physics goals within a realistically feasible timescale,
and produce significant new results at each stage.Comment: 30 pages, 32 pdf figures, 6 table
Neutrino oscillation physics at an upgraded CNGS with large next generation liquid Argon TPC detectors
The determination of the missing element (magnitude and phase) of
the PMNS neutrino mixing matrix is possible via the detection of \numu\to\nue
oscillations at a baseline and energy given by the atmospheric
observations, corresponding to a mass squared difference . While the current optimization of the CNGS
beam provides limited sensitivity to this reaction, we discuss in this document
the physics potential of an intensity upgraded and energy re-optimized CNGS
neutrino beam coupled to an off-axis detector. We show that improvements in
sensitivity to compared to that of T2K and NoVA are possible with
a next generation large liquid Argon TPC detector located at an off-axis
position (position rather distant from LNGS, possibly at shallow depth). We
also address the possibility to discover CP-violation and disentangle the mass
hierarchy via matter effects. The considered intensity enhancement of the CERN
SPS has strong synergies with the upgrade/replacement of the elements of its
injector chain (Linac, PSB, PS) and the refurbishing of its own elements,
envisioned for an optimal and/or upgraded LHC luminosity programme.Comment: 37 pages, 20 figure
A low energy optimization of the CERN-NGS neutrino beam for a theta_{13} driven neutrino oscillation search
The possibility to improve the CERN to Gran Sasso neutrino beam performances
for theta_{13} searches is investigated. We show that by an appropriate
optimization of the target and focusing optics of the present CNGS design, we
can increase the flux of low energy neutrinos by about a factor 5 compared to
the current tau optimized focalisation. With the ICARUS 2.35 kton detector at
LNGS and in case of negative result, this would allow to improve the limit to
sin^22 theta_{13} by an order of magnitude better than the current limit of
CHOOZ at Delta m^2 approximately 3 times 10^{-3} eV^2 within 5 years of nominal
CNGS running. This is by far the most sensitive setup of the currently approved
long-baseline experiments and is competitive with the proposed JHF superbeam.Comment: 19 pages, 8 figure
European Strategy for Accelerator-Based Neutrino Physics
Massive neutrinos reveal physics beyond the Standard Model, which could have
deep consequences for our understanding of the Universe. Their study should
therefore receive the highest level of priority in the European Strategy. The
discovery and study of leptonic CP violation and precision studies of the
transitions between neutrino flavours require high intensity, high precision,
long baseline accelerator neutrino experiments. The community of European
neutrino physicists involved in oscillation experiments is strong enough to
support a major neutrino long baseline project in Europe, and has an ambitious,
competitive and coherent vision to propose. Following the 2006 European
Strategy for Particle Physics (ESPP) recommendations, two complementary design
studies have been carried out: LAGUNA/LBNO, focused on deep underground
detector sites, and EUROnu, focused on high intensity neutrino facilities.
LAGUNA LBNO recommends, as first step, a conventional neutrino beam CN2PY from
a CERN SPS North Area Neutrino Facility (NANF) aimed at the Pyhasalmi mine in
Finland. A sterile neutrino search experiment which could also be situated in
the CERN north area has been proposed (ICARUS-NESSIE) using a two detector
set-up, allowing a definitive answer to the 20 year old question open by the
LSND experiment. EUROnu concluded that a 10 GeV Neutrino Factory, aimed at a
magnetized neutrino detector situated, also, at a baseline of around 2200 km
(+-30%), would constitute the ultimate neutrino facility; it recommends that
the next 5 years be devoted to the R&D, preparatory experiments and
implementation study, in view of a proposal before the next ESPP update. The
coherence and quality of this program calls for the continuation of neutrino
beams at CERN after the CNGS, and for a high priority support from CERN and the
member states to the experiments and R&D program.Comment: Prepared by the program committee of the Neutrino `town meeting',
CERN, 14-16 May 2012 and submitted to the European Strategy For European
Particle Physic
Dark sectors 2016 Workshop: community report
This report, based on the Dark Sectors workshop at SLAC in April 2016,
summarizes the scientific importance of searches for dark sector dark matter
and forces at masses beneath the weak-scale, the status of this broad
international field, the important milestones motivating future exploration,
and promising experimental opportunities to reach these milestones over the
next 5-10 years
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