Biomedical subjects

M S Dubrovin

Publications and source records attributed to M S Dubrovin.

5 recordsLinked to original sources

PubMed2001

Measurement of J/psi production in continuum e(+)e(-) annihilations near square root of s = 10.6 GeV.

The production of J/psi mesons in continuum e(+)e(-) annihilations has been studied with the BABAR detector at energies near the Upsilon(4S) resonance. The mesons are distinguished from J/psi production in B decays through their center-of-mass momentum and energy. We measure the cross section e(+)e(-)-->J/psi X to be 2.52+/-0.21+/-0.21 pb. We set a 90% C.L. upper limit on the branching fraction for direct Upsilon(4S)-->J/psi X decays at 4.7 x 10(-4).

Journal Article↗

PubMed2001

Measurement of branching fractions and search for CP-violating charge asymmetries in charmless two-body B decays into pions and kaons.

We present measurements, based on a sample of approximately 23x10(6) BB pairs, of the branching fractions and a search for CP-violating charge asymmetries in charmless hadronic decays of B mesons into two-body final states of kaons and pions. We find the branching fractions B(B0-->pi(+)pi(-)) = (4.1+/-1.0+/-0.7)x10(-6), B(B0-->K+pi(-)) = (16.7+/-1.6+/-1.3)x10(-6), B(B+-->K+pi(0)) = (10.8(+2.1)(-1.9)+/-1.0)x10(-6), B(B+-->K0pi(+)) = (18.2(+3.3)(-3.0)+/-2.0)x10(-6), B(B0-->K0pi(0)) = (8.2(+3.1)(-2.7)+/-1.2)x10(-6). We also report 90% confidence level upper limits for B meson decays to the pi(+)pi(0), K+K-, and K0K+ final states. In addition, charge asymmetries have been found to be consistent with zero, where the statistical precision is in the range of +/-0.10 to +/-0.18, depending on the decay mode.

Journal Article↗

PubMed2001

Measurement of the decays B--> phiK and B--> phiK*.

We have observed the decays B--> phiK and phiK(*) in a sample of over 45 million B mesons collected with the BABAR detector at the PEP-II collider. The measured branching fractions are B(B+--> phiK+) = (7.7(+1.6)(-1.4)+/-0.8)x10(-6), B(B0--> phiK0) = (8.1(+3.1)(-2.5)+/-0.8)x10(-6), B(B+--> phiK(*+)) = (9.7(+4.2)(-3.4)+/-1.7)x10(-6), and B(B0--> phiK(*0)) = (8.7(+2.5)(-2.1)+/-1.1)x10(-6). We also report the upper limit B(B+--> phipi(+))<1.4x10(-6) ( 90% C.L.).

Journal Article↗

PubMed2001

Direct measurement of the phi(1020) leptonic branching ratio.

The process e(+)e(-)-->mu(+)mu(-) has been studied by the SND detector at the VEPP-2M e(+)e(-) collider in the phi(1020)-resonance energy region. The measured effective phi meson leptonic branching ratio B(phi-->l(+)l(-)) identical with square root of B(phi-->e(+)e(-))B(phi-->mu(+)mu(-))] = (2.89 +/- 0.10 +/- 0.06) x 10(-4) agrees well with the Particle Data Group value B(phi-->e(+)e(-)) = (2.91 +/- 0.07) x 10(-4), confirming mu-e universality. Without additional assumption of mu-e universality the branching ratio B(phi-->mu(+)mu(-)) = (2.87 +/- 0.20 +/- 0.14) x 10(-4) was obtained.

Journal Article↗

PubMed1998

One- and Two-Coordinate Detectors in BINP.

One- and two-coordinate detectors with proportional chambers developed at the Budker Institute of Nuclear Physics (BINP) are presented. The parallax-free 10 MHz one-coordinate OD-3.1 and OD-3.2 detectors are used in synchrotron radiation powder diffraction and SAXS experiments. The two-coordinate DED-3 detector with a multiwire proportional chamber (MWPC) is used in Laue diffraction. The latest modification of this detector, DED-5, with a working area of 384 x 384 mm, is briefly described. The micro-strip detector prototype MSGC-100 has passed test synchrotron radiation experiments and the next modification (MSGC-500), with 500 channels for high energy, is under construction. The one-coordinate MWPC OD-160 detector, with an angle aperture of 160 degrees and a count rate of 3.3 GHz, is under construction. It will be used for high-resolution powder diffraction. Two types of gas chamber will be used: L for low energies (5-30 keV) and H for high energies (30-70 keV). A 16 degrees section with an H-chamber has been produced and tested on the synchrotron radiation beamline.

Journal Article↗