253 research outputs found
Different approaches to calculate the decay width
The rare decay, currently under analysis by the
NA48/2 Collaboration, is considered. We have performed two theoretical
approaches to calculate the differential decay width -- in the kaon rest frame,
where we use Cabibbo-Maksimovicz variables, and in the center-of-mass system of
the lepton pair. The latter essentially simplifies the computations. A
comparison between the two approaches has been performed. We have also found
the dependencies of the differential decay rate as a function of the virtual
photon and dipion system massesComment: 10 pages,5 figure
Minimally Invasive Urological Interventions in Outpatient Clinic on the Example of Prostate Biopsy
One of the main directions of improving medical care was the introduction of inpatient forms of medical care for patients who do not require round-the-clock supervision.Aim of the research: to prove the effectiveness and economic feasibility of minimally invasive procedures in outpatient conditions.Materials and methods. The study included 3524 patients in the period from 2010 to 2017, who underwent transrectal prostate biopsy on the basis of the Department of urology of polyclinic No. 195 of the Western district of Moscow. For comparison, the patients were taken, who underwent a biopsy of the prostate gland at the base hospital No. 31, No. 51, No. 17.Results. The average number of biopsies performed in hospital No. 31, No. 51 and No. 17 for the year amounted to 344 biopsies, and the average detectability of prostate cancer was 142 (41.3 %). The average number of biopsies per year in the urology department of the branch number 2 GP No. 195 amounted to 440.5, and the average detectability of prostate cancer – 152.8 (34.7 %). Thus, with comparable inpatient detection of prostate cancer in one large outpatient urology center, an average of 28 % more biopsies are performed (440.5 versus 344) than in 3 hospitals over a comparable period of time.Conclusions. Inpatient technologies can reduce the burden on hospitals. The development of hospital-replacing forms is determined by the need of the population and for efficient use of financial and technical resources of health care
Cusps in K_L --> 3 pi decays
The pion mass difference generates a pronounced cusp in K --> 3 pi decays,
the strength of which is related to the pi pi S-wave scattering lengths. We
apply an effective field theory framework developed earlier to evaluate the
amplitudes for K_L --> 3 pi decays in a systematic manner, where the strictures
imposed by analyticity and unitarity are respected automatically. The
amplitudes for the decay eta --> 3 pi are also given.Comment: 15 pages, 3 figures, uses Elsevier styl
Enhancement of low-mass dileptons in ultraperipheral collisions
It is shown that production of low-mass -pairs in ultraperipheral
nuclear collisions is enhanced due to the Sommerfeld-Gamow-Sakharov (SGS)
factor. This effect is especially strong near the threshold of creation of
unbound -pairs with low masses in the two-photon fusion. Coulomb
attraction of the non-relativistic components of such pairs may lead to the
increased intensity of 511 keV photons. It can be recorded at the NICA collider
and has some astrophysical implications. The analogous effect can be observed
at LHC in dilepton production.Comment: 10 p., 3 Fig
The electromagnetic effects in decay
The final state interaction of pions in decay allows one to obtain
the value of the isospin and angular momentum zero scattering length
.We take into account the electromagnetic interaction of pions and
isospin symmetry breaking effects caused by different masses of neutral and
charged pions and estimate the impact of these effects on the procedure of
scattering length extraction from decay.Comment: 8 pages,1 figur
Final state interaction in kaons decays
The kaons decays to the pairs of charged and neutral pions are considered in
the framework of the non-relativistic quantum mechanics. The general
expressions for the decay amplitudes to the two different channels accounting
for the strong interaction between pions are obtained. The developed approach
allows one to estimate the contribution of terms of any order in strong
interaction and correctly takes into account the electromagnetic interaction
between the pions in the final state.Comment: 8 page
Radiative corrections in K --> 3 pi decays
We investigate radiative corrections to K --> 3 pi decays. In particular, we
extend the non-relativistic framework developed recently to include real and
virtual photons and show that, in a well-defined power counting scheme, the
results reproduce corrections obtained in the relativistic calculation. Real
photons are included exactly, beyond the soft-photon approximation, and we
compare the result with the latter. The singularities generated by pionium near
threshold are investigated, and a region is identified where standard
perturbation theory in the fine structure constant alpha may be applied. We
expect that the formulae provided allow one to extract S-wave pi pi scattering
lengths from the cusp effect in these decays with high precision.Comment: 57 pages, 17 figure
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