21 research outputs found
Constraints on axion-like polarization oscillations in the cosmic microwave background with POLARBEAR
Very light pseudoscalar fields, often referred to as axions, are compelling
dark matter candidates and can potentially be detected through their coupling
to the electromagnetic field. Recently a novel detection technique using the
cosmic microwave background (CMB) was proposed, which relies on the fact that
the axion field oscillates at a frequency equal to its mass in appropriate
units, leading to a time-dependent birefringence. For appropriate oscillation
periods this allows the axion field at the telescope to be detected via the
induced sinusoidal oscillation of the CMB linear polarization. We search for
this effect in two years of POLARBEAR data. We do not detect a signal, and
place a median upper limit of on the sinusoid amplitude
for oscillation frequencies between and
, which corresponds to axion masses between and . Under the
assumptions that 1) the axion constitutes all the dark matter and 2) the axion
field amplitude is a Rayleigh-distributed stochastic variable, this translates
to a limit on the axion-photon coupling .Comment: 17 pages, 5 figures, 2 tables. Published in Physical Review
t(7;11)(p15;p15) chronic myeloid leukaemia developed into blastic transformation showing a novel NUP98/HOXA11
Pancreaticobiliary maljunction (PBM) complicated with complete pancreas divisum
A rare pediatric case of pancreaticobiliary maljunction (PBM) with pancreas divisum is reported. The case showed extremely rare arrangement of the biliary tree and pancreatic duct; the common channel usually seen in PBM did not exist and the common bile duct was connected to the dorsal pancreatic duct via a dilated intermediary duct, in which a large protein plug had formed. The common bile duct was not dilated at all. All of these anomalies may have been caused by abnormal development of the ventral and dorsal pancreatic ducts at an early gestational age.We report a very rare pediatric case of pancreaticobiliary maljunction (PBM) complicated with pancreas divisum. In this case, the common bile duct showed a normal caliber and it was connected to the dorsal pancreatic duct through an intermediary dilated duct, which contained a protein plug that dammed up bile and pancreatic juice flow. This anomaly is very similar to type IIIc3 choledochal cyst, whose classification was addressed by Komi et al. (1), but it differed in the following point; in our case, the common bile duct did not connect to the duodenum through the ampulla of Vater (the common channel was absent) and bile was drained to the duodenum through Santorini duct. These quite rare anomalies might have been caused in the fetus by some kind of maldevelopment of the ventral and dorsal pancreatic ducts. Keywords: Pancreaticobiliary maljunction, Pancreas divisum, Pancreatiti
Effects of Carbon and Nitrogen Additions on Mechanical Stability of Metastable Austenitic Stainless Steel
Development and validation of speed loss for a blunt-shaped ship in two rough sea voyages in the Southern Hemisphere
Exploration of the polarization angle variability of the Crab Nebula with POLARBEAR and its application to the search for axion-like particles
International audienceThe Crab Nebula, also known as Tau A, is a polarized astronomical source at millimeter wavelengths. It has been used as a stable light source for polarization angle calibration in millimeter-wave astronomy. However, it is known that its intensity and polarization vary as a function of time at a variety of wavelengths. Thus, it is of interest to verify the stability of the millimeter-wave polarization. If detected, polarization variability may be used to better understand the dynamics of Tau A, and for understanding the validity of Tau~A as a calibrator. One intriguing application of such observation is to use it for the search of axion-light particles (ALPs). Ultralight ALPs couple to photons through a Chern-Simons term, and induce a temporal oscillation in the polarization angle of linearly polarized sources. After assessing a number of systematic errors and testing for internal consistency, we evaluate the variability of the polarization angle of the Crab Nebula using 2015 and 2016 observations with the 150 GHz POLARBEAR instrument. We place a median 95% upper bound of polarization oscillation amplitude over the oscillation frequencies from to . Assuming that no sources other than ALP are causing Tau A's polarization angle variation, that the ALP constitutes all the dark matter, and that the ALP field is a stochastic Gaussian field, this bound translates into a median 95% upper bound of ALP-photon coupling in the mass range from to . This demonstrates that this type of analysis using bright polarized sources is as competitive as those using the polarization of cosmic microwave background in constraining ALPs
Exploration of the polarization angle variability of the Crab Nebula with POLARBEAR and its application to the search for axion-like particles
International audienceThe Crab Nebula, also known as Tau A, is a polarized astronomical source at millimeter wavelengths. It has been used as a stable light source for polarization angle calibration in millimeter-wave astronomy. However, it is known that its intensity and polarization vary as a function of time at a variety of wavelengths. Thus, it is of interest to verify the stability of the millimeter-wave polarization. If detected, polarization variability may be used to better understand the dynamics of Tau A, and for understanding the validity of Tau~A as a calibrator. One intriguing application of such observation is to use it for the search of axion-light particles (ALPs). Ultralight ALPs couple to photons through a Chern-Simons term, and induce a temporal oscillation in the polarization angle of linearly polarized sources. After assessing a number of systematic errors and testing for internal consistency, we evaluate the variability of the polarization angle of the Crab Nebula using 2015 and 2016 observations with the 150 GHz POLARBEAR instrument. We place a median 95% upper bound of polarization oscillation amplitude over the oscillation frequencies from to . Assuming that no sources other than ALP are causing Tau A's polarization angle variation, that the ALP constitutes all the dark matter, and that the ALP field is a stochastic Gaussian field, this bound translates into a median 95% upper bound of ALP-photon coupling in the mass range from to . This demonstrates that this type of analysis using bright polarized sources is as competitive as those using the polarization of cosmic microwave background in constraining ALPs