Search results for "annihilation"
showing 10 items of 1016 documents
Measurement of the form factors in the decayD+→ωe+νeand search for the decayD+→ϕe+νe
2015
Using 2.92 fb(-1) of electron-positron annihilation data collected at a center-of-mass energy of root s = 3.773 GeV with the BESIII detector, we present an improved measurement of the branching fra ...
B-physics results from LEP
1996
Abstract The LEP collider continues to improve our knowledge and understanding of B-physics. Recent results are presented in the areas of B-hadron lifetimes, BB oscillations, B-spectroscopy and rare B-decays.
QED box amplitude in heavy fermion production
2002
We evaluate the two-photon box contribution to heavy fermion production in electron positron annihilation, that provides O(alpha^2) electromagnetic corrections to the Born cross section. The study of its non-relativistic expansion, relevant at energies close to the threshold of production, is also performed. We also verify that the threshold expansion of the one-loop integrals correctly reproduces our results, thus extending the applicability of this technique to heavy fermion production diagrams.
Measurement of the Inclusive Charmless Semileptonic Branching Ratio ofBMesons and Determination of|Vub|
2004
We report a measurement of the inclusive charmless semileptonic branching fraction of B mesons in a sample of 89 x 10(6) (-)BB events recorded with the BABAR detector at the Upsilon(4S) resonance. Events are selected by fully reconstructing the decay of one B meson and identifying a charged lepton from the decay of the other B meson. The number of signal events is extracted from the mass distribution of the hadronic system accompanying the lepton and is used to determine the ratio of branching fractions B((-)B-->X(u)lnu;)/B((-)B-->Xlnu;)=[2.06+/-0.25(stat)+/-0.23(syst)+/-0.36(theo)]x10(-2). Using the measured branching fraction for inclusive semileptonic B decays, we find B((-)B-->X(u)lnu;)…
Observation of a Charged Charmoniumlike Structure ine+e−→(D*D¯*)±π∓ats=4.26 GeV
2014
We study the process e(+)e(-) -> (D* (D) over bar*)(+/-)pi(-/+) at a center-of-mass energy of 4.26 GeV using a 827 pb(-1) data sample obtained with the BESIII detector at the Beijing Electron Positron Collider. Based on a partial reconstruction technique, the Born cross section is measured to be (137 +/- 9 +/- 15) pb. We observe a structure near the (D* (D) over bar*)(+/-) threshold in the pi(-/+) recoil mass spectrum, which we denote as the Z(c)(+/-) (4025). The measured mass and width of the structure are (4026.3 +/- 2.6 +/- 3.7) MeV/c(2) and (24.8 +/- 5.6 +/- 7.7) MeV, respectively. Its production ratio sigma(e(+)e(-) -> Z(c)(+/-)(4025)pi(-/+)-> (D* (D) over bar*)(+/-)pi(-/+)/sigma(e(+)e…
Electronic Processes in Solid State: Dirac Framework
2019
The present paper proposes canonical Dirac framework adapted for application to the electronic processes in solid state. The concern is a spatially periodic structure of atoms distinguished by birth and annihilation of particle states excited due to interaction with the electromagnetic field. This implies replacing the conventional energy-momentum relation specific of the canonical Dirac framework and permissible for particle physics by a case specific relation available for the solid state. The advancement is a unified and consistent mathematical framework incorporating the Hilbert space, the quantum field, and the special relativity. Essential details of the birth and annihilation of the …
Dark matter synchrotron emission and radio observations
2012
We compute the synchrotron emission induced by electrons produced by DM annihilations inside our galaxy. The signal is compared with observations in a large range of frequencies, from 22 MHz up to 1420 MHz. We set constraints on the DM mass and annihilation cross-section and highlight the impact of astrophysical uncertainties.
Antideuterons as an indirect dark matter signature: design and preparation for a balloon-born GAPS experiment
2008
The General Antiparticle Spectrometer (GAPS) exploits low energy antideuterons produced in neutralino-neutralino annihilations as an indirect dark matter (DM) signature that is effectively free from background. When an antiparticle is captured by a target material, it forms an exotic atom in an excited state which quickly decays by emitting X-rays of precisely defined energy and a correlated pion signature from nuclear annihilation. We have successfully demonstrated the GAPS method in an accelerator environment and are currently planning a prototype flight from Japan for 2009. This will lead to a long duration balloon (LDB) mission that will complement existing and planned direct DM searche…
Right-handed neutrino magnetic moments
2009
PACS numbers: 14.60.St, 13.15.+g, 13.35.Hb, 13.66.Hk
The topology dependence of charged particle multiplicities in three-jet events
1997
A study of individual jet and whole-event charged particle multiplicities in three-jet events measured in e(+)e(-) annihilation at the Z reveals a significant topology dependence. Mean jet multiplicities are inadequately described by jet energies; interjet angles must also be specified. Quantitative tests suggest that it is necessary to use transverse-momentum-like scales to describe the data. RI ANTONELLI, ANTONELLA/C-6238-2011; Passalacqua, Luca/F-5127-2011; Murtas, Fabrizio/B-5729-2012; St.Denis, Richard/C-8997-2012; Sanchez, Federico/F-5809-2012; Forti, Francesco/H-3035-2011; Ferrante, Isidoro/F-1017-2012