University of Warsaw

About: University of Warsaw is a education organization based out in Warsaw, Poland. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 20832 authors who have published 56617 publications receiving 1185084 citations. The organization is also known as: Uniwersytet Warszawski & Warsaw University.

Atmospheric neutrino oscillation analysis with subleading effects in Super-Kamiokande I, II, and III

Abstract: We present a search for nonzero {theta}{sub 13} and deviations of sin{sup 2{theta}}{sub 23} from 0.5 in the oscillations of atmospheric neutrino data from Super-Kamiokande I, II, and III. No distortions of the neutrino flux consistent with nonzero {theta}{sub 13} are found and both neutrino mass hierarchy hypotheses are in agreement with the data. The data are best fit at {Delta}m{sup 2}=2.1x10{sup -3} eV{sup 2}, sin{sup 2{theta}}{sub 13}=0.0, and sin{sup 2{theta}}{sub 23}=0.5. In the normal (inverted) hierarchy {theta}{sub 13} and {Delta}m{sup 2} are constrained at the one-dimensional 90% C.L. to sin{sup 2{theta}}{sub 13}<0.04(0.09) and 1.9(1.7)x10{sup -3}<{Delta}m{sup 2}<2.6(2.7)x10{sup -3} eV{sup 2}. The atmospheric mixing angle is within 0.407{<=}sin{sup 2{theta}}{sub 23{<=}}0.583 at 90% C.L.

Neutron and weak-charge distributions of the 48Ca nucleus

Abstract: What is the size of the atomic nucleus? This deceivably simple question is difficult to answer. Although the electric charge distributions in atomic nuclei were measured accurately already half a century ago, our knowledge of the distribution of neutrons is still deficient. In addition to constraining the size of atomic nuclei, the neutron distribution also impacts the number of nuclei that can exist and the size of neutron stars. We present an ab initio calculation of the neutron distribution of the neutron-rich nucleus Ca-48. We show that the neutron skin (difference between the radii of the neutron and proton distributions) is significantly smaller than previously thought. We also make predictions for the electric dipole polarizability and the weak form factor; both quantities that are at present targeted by precision measurements. Based on ab initio results for Ca-48, we provide a constraint on the size of a neutron star.

The ASAS-SN catalogue of variable stars I: The Serendipitous Survey

Abstract: The All-Sky Automated Survey for Supernovae (ASAS-SN) is the first optical survey to routinely monitor the whole sky with a cadence of $\sim2-3$ days down to V$\lesssim17$ mag. ASAS-SN has monitored the whole sky since 2014, collecting $\sim100-500$ epochs of observations per field. The V-band light curves for candidate variables identified during the search for supernovae are classified using a random forest classifier and visually verified. We present a catalog of 66,179 bright, new variable stars discovered during our search for supernovae, including 27,479 periodic variables and 38,700 irregular variables. V-band light curves for the ASAS-SN variables are available through the ASAS-SN variable stars database (this https URL). The database will begin to include the light curves of known variable stars in the near future along with the results for a systematic, all-sky variability survey.

The Rate of Binary Black Hole Mergers Inferred from Advanced LIGO Observations Surrounding GW150914

Abstract: A transient gravitational-wave signal, GW150914, was identified in the twin Advanced LIGO detectors on September 14, 2015 at 09:50:45 UTC. To assess the implications of this discovery, the detectors remained in operation with unchanged configurations over a period of 39 d around the time of the signal. At the detection statistic threshold corresponding to that observed for GW150914, our search of the 16 days of simultaneous two-detector observational data is estimated to have a false alarm rate (FAR) of < 4.9 × 10^(−6) yr^(−1), yielding a p-value for GW150914 of < 2 × 10^(−7). Parameter estimation followup on this trigger identifies its source as a binary black hole (BBH) merger with component masses (m_1, m_2) = (36^(+5)_(−4), 29^(+4)_(−4)) M_⊙ at redshift z = 0.09^(+0.03)_(−0.04) (median and 90\% credible range). Here we report on the constraints these observations place on the rate of BBH coalescences. Considering only GW150914, assuming that all BBHs in the Universe have the same masses and spins as this event, imposing a search FAR threshold of 1 per 100 years, and assuming that the BBH merger rate is constant in the comoving frame, we infer a 90% credible range of merger rates between 2--53 Gpc^(−3) yr^(−1) (comoving frame). Incorporating all search triggers that pass a much lower threshold while accounting for the uncertainty in the astrophysical origin of each trigger, we estimate a higher rate, ranging from 13--600 Gpc^(−3) yr^(−1) depending on assumptions about the BBH mass distribution. All together, our various rate estimates fall in the conservative range 2--600 Gpc^(−3) yr^(−1).