127 research outputs found
Light Higgsino from Axion Dark Radiation
The recent observations imply that there is an extra relativistic degree of
freedom coined dark radiation. We argue that the QCD axion is a plausible
candidate for the dark radiation, not only because of its extremely small mass,
but also because in the supersymmetric extension of the Peccei-Quinn mechanism
the saxion tends to dominate the Universe and decays into axions with a sizable
branching fraction. We show that the Higgsino mixing parameter mu is bounded
from above when the axions produced at the saxion decays constitute the dark
radiation: mu \lesssim 300 GeV for a saxion lighter than 2m_W, and mu less than
the saxion mass otherwise. Interestingly, the Higgsino can be light enough to
be within the reach of LHC and/or ILC even when the other superparticles are
heavy with mass about 1 TeV or higher. We also estimate the abundance of axino
produced by the decays of Higgsino and saxion.Comment: 18 pages, 1 figure; published in JHE
Gravitino Dark Matter in Tree Level Gauge Mediation with and without R-parity
We investigate the cosmological aspects of Tree Level Gauge Mediation, a
recently proposed mechanism in which the breaking of supersymmetry is
communicated to the soft scalar masses by extra gauge interactions at the tree
level. Embedding the mechanism in a Grand Unified Theory and requiring the
observability of sfermion masses at the Large Hadron Collider, it follows that
the Lightest Supersymmetric Particle is a gravitino with a mass of the order of
10 GeV. The analysis in the presence of R-parity shows that a typical Tree
Level Gauge Mediation spectrum leads to an overabundance of the Dark Matter
relic density and a tension with the constraints from Big Bang Nucleosynthesis.
This suggests to relax the exact conservation of the R-parity. The underlying
SO(10) Grand Unified Theory together with the bounds from proton decay provide
a rationale for considering only bilinear R-parity violating operators. We
finally analyze the cosmological implications of this setup by identifying the
phenomenologically viable regions of the parameter space.Comment: 28 pages, 5 figures. References added. To appear in JHE
Dark Radiation and Dark Matter in Large Volume Compactifications
We argue that dark radiation is naturally generated from the decay of the
overall volume modulus in the LARGE volume scenario. We consider both
sequestered and non-sequestered cases, and find that the axionic superpartner
of the modulus is produced by the modulus decay and it can account for the dark
radiation suggested by observations, while the modulus decay through the
Giudice-Masiero term gives the dominant contribution to the total decay rate.
In the sequestered case, the lightest supersymmetric particles produced by the
modulus decay can naturally account for the observed dark matter density. In
the non-sequestered case, on the other hand, the supersymmetric particles are
not produced by the modulus decay, since the soft masses are of order the heavy
gravitino mass. The QCD axion will then be a plausible dark matter candidate.Comment: 27 pages, 4 figures; version 3: version published in JHE
Mindful breath awareness meditation facilitates efficiency gains in brain networks: A steady-state visually evoked potentials study
The beneficial effects of mindfulness-based therapeutic interventions have stimulated a rapidly growing body of scientific research into underlying psychological processes. Resulting evidence indicates that engaging with mindfulness meditation is associated with increased performance on a range of cognitive tasks. However, the mechanisms promoting these improvements require further investigation. We studied changes in behavioural performance of 34 participants during a multiple object tracking (MOT) task that taps core cognitive processes, namely sustained selective visual attention and spatial working memory. Concurrently, we recorded the steady-state visually evoked potential (SSVEP), an EEG signal elicited by the continuously flickering moving objects, and indicator of attentional engagement. Participants were tested before and after practicing eight weeks of mindful breath awareness meditation or progressive muscle relaxation as active control condition. The meditation group improved their MOT-performance and exhibited a reduction of SSVEP amplitudes, whereas no such changes were observed in the relaxation group. Neither group changed in self-reported positive affect and mindfulness, while a marginal increase in negative affect was observed in the mindfulness group. This novel way of combining MOT and SSVEP provides the important insight that mindful breath awareness meditation may lead to refinements of attention networks, enabling more efficient use of attentional resources
Planck 2015 results. XIII. Cosmological parameters
We present results based on full-mission Planck observations of temperature and polarization anisotropies of the CMB. These data are consistent with the six-parameter inflationary LCDM cosmology. From the Planck temperature and lensing data, for this cosmology we find a Hubble constant, H0= (67.8 +/- 0.9) km/s/Mpc, a matter density parameter Omega_m = 0.308 +/- 0.012 and a scalar spectral index with n_s = 0.968 +/- 0.006. (We quote 68% errors on measured parameters and 95% limits on other parameters.) Combined with Planck temperature and lensing data, Planck LFI polarization measurements lead to a reionization optical depth of tau = 0.066 +/- 0.016. Combining Planck with other astrophysical data we find N_ eff = 3.15 +/- 0.23 for the effective number of relativistic degrees of freedom and the sum of neutrino masses is constrained to < 0.23 eV. Spatial curvature is found to be |Omega_K| < 0.005. For LCDM we find a limit on the tensor-to-scalar ratio of r <0.11 consistent with the B-mode constraints from an analysis of BICEP2, Keck Array, and Planck (BKP) data. Adding the BKP data leads to a tighter constraint of r < 0.09. We find no evidence for isocurvature perturbations or cosmic defects. The equation of state of dark energy is constrained to w = -1.006 +/- 0.045. Standard big bang nucleosynthesis predictions for the Planck LCDM cosmology are in excellent agreement with observations. We investigate annihilating dark matter and deviations from standard recombination, finding no evidence for new physics. The Planck results for base LCDM are in agreement with BAO data and with the JLA SNe sample. However the amplitude of the fluctuations is found to be higher than inferred from rich cluster counts and weak gravitational lensing. Apart from these tensions, the base LCDM cosmology provides an excellent description of the Planck CMB observations and many other astrophysical data sets
Direct stau production at hadron colliders in cosmologically motivated scenarios
We calculate dominant cross section contributions for stau pair production at
hadron colliders within the MSSM, taking into account left-right mixing of the
stau eigenstates. We find that b-quark annihilation and gluon fusion can
enhance the cross sections by more than one order of magnitude with respect to
the Drell-Yan predictions. These additional production channels are not yet
included in the common Monte Carlo analysis programs and have been neglected in
experimental analyses so far. For long-lived staus, we investigate differential
distributions and prospects for their stopping in the collider detectors. New
possible strategies are outlined to determine the mass and width of the heavy
CP-even Higgs boson H0. Scans of the relevant regions in the CMSSM are
performed and predictions are given for the current experiments at the LHC and
the Tevatron. The obtained insights allow us to propose collider tests of
cosmologically motivated scenarios with long-lived staus that have an
exceptionally small thermal relic abundance.Comment: 49 pages, 13 figures; v2: references added, typos corrected, text
streamlined, results unchange
Patient-tailored adoptive immunotherapy with EBV-specific T cells from related and unrelated donors
BACKGROUND: Adoptive transfer of EBV-specific T cells can restore specific immunity in immunocompromised patients with EBV-associated complications. METHODS: We provide results of a personalized T-cell manufacturing program evaluating donor, patient, T-cell product and outcome data. Patient-tailored clinical-grade EBV-specific cytotoxic T-lymphocyte (EBV-CTL) products from stem cell donors (SCD), related third party donors (TPD) or unrelated TPD from the allogeneic T-cell donor registry (alloCELL) established at Hannover Medical School were manufactured by immunomagnetic selection using CliniMACS Plus or Prodigy device and EBV PepTivators EBNA-1 and Select. Consecutive manufacturing processes were evaluated and patient outcome and side effects were retrieved by retrospective chart analysis. RESULTS: Forty clinical-grade EBV-CTL products from SCDs, related or unrelated TPDs were generated for 37 patients with and without transplantation (Tx) history within 5 days (median) after donor identification. 34 patients received 1-14 EBV-CTL products (fresh and cryopreserved). EBV-CTL transfer led to complete response in 20 of 29 patients who were evaluated for clinical response. No infusion-related toxicity was reported. EBV-specific T cells in patients' blood were detectable in 16/18 monitored patients (89 %) after transfer and correlated with clinical response. CONCLUSION: In conclusion, personalized clinical-grade manufacturing of EBV-CTL products via immunomagnetic selection from SCD, related or unrelated TPD is feasible in a timely manner. Overall, EBV-CTL were clinically effective and well-tolerated. Our data suggest EBV-CTL as promising therapeutic approach for immunocompromised patients with refractory EBV-associated diseases beyond HSCT as well as patients with pre-existing organ dysfunction
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