133,836 research outputs found
On the perturbative generation of the higher-derivative Lorentz-breaking terms
In this paper, we describe the perturbative generation of the
higher-derivative Lorentz-breaking terms for the gauge field, that is, the
Myers-Pospelov term and the higher-derivative Carroll-Field-Jackiw term. These
terms are explicitly calculated in the one-loop approximation and shown to be
finite and ambiguous.Comment: 12 pages, version accepted to PR
On the Adler-Bell-Jackiw anomaly in a Horava-Lifshitz-like QED
We show the absence of the ABJ anomaly for the Horava-Lifshitz-like QED with
any even . Besides of this, we study the graph contributing to the ABJ
anomaly at non-zero temperature and extend the Fujikawa's methodology of
studying the integral measure for our model.Comment: 9 pages, version accepted to EP
New powerful outburst of the unusual young star V1318 Cyg S (LkH{\alpha} 225)
Young double star V1318 Cyg, which is associated with a small isolated
star-forming region around HAeBe star BD+40o4124, has very unusual photometric
and spectral behavior. We present results of photometric and spectroscopic
observations in the optical range. We carried out BVRI CCD photometric
observations of V1318 Cyg from 2015 Sept. to 2017 July. For the same period we
acquired medium- and low-resolution spectra. Observations were performed with
the 2.6 m telescope. We analyze the historical light curve for V1318 Cyg and
demonstrate that the southern component, V1318 Cyg S, after being rather bright
in the 1970s (V14 mag) started to lower its brightness and in 1990
became practically invisible in the optical. After its reappearance in the
second half of the 1990s the star started to become very slowly brighter.
Between 2006 and 2010 V1318 Cyg S started brightening more quickly, and in 2015
had become brighter by more than five magnitudes in visible light. Since this
time V1318 Cyg S has remained at this maximum. Its spectrum shows little
variability and consists of a mixture of emission and absorption lines, which
has allowed for estimates of its spectral type as early Ae, with obvious
evidence of matter outflow. We derive its current A(V) 7.2 and L = 750
L(sun) thus confirming that V1318 Cyg S should belong to the Herbig Ae stars,
making it, along with BD+40o4124 and V1686 Cyg, the third luminous young star
in the group. It is very probable that we observe V1318 Cyg S near the pole and
that the inclination of its dense and slow ( 100 km/s) outflow is low.
The unusual variability and other features of V1318 Cyg S make it difficult to
classify this star among known types of eruptive young stars. It could be an
extreme, higher-mass example of an EXor, or an object of intermediate class
between EXors and FUors, like V1647 Ori.Comment: 9 pages, 7 figure
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