نتایج جستجو برای: charge radius
تعداد نتایج: 187015 فیلتر نتایج به سال:
A Majorana neutrino is characterized by just one flavor diagonal electromagnetic form factor: the anapole moment, that in the static limit corresponds to the axial vector charge radius 〈 r2 A 〉 . As is the case for the vector charge radius of a Dirac neutrino, proving that this quantity is a well defined physical quantity is non trivial. I will first describe briefly the origin of the long stan...
Sen has shown that tachyon condensation in Dbrane–anti-Dbrane configurations can lead to remarkable connections between string theories. A consequence of his results is that there is a minimal value of the radial coördinate r c ∝ √ α ′ g 1/(9−p) such that Dpbrane charge cannot be localized to values smaller than r c. At this value of r c the curvature and the gradient of the Ramond-Ramond field...
We review the status of the proton charge radius puzzle. Emphasis is given to the various experiments initiated to resolve the conflict between the muonic hydrogen results and the results from scattering and regular hydrogen spectroscopy. 1 The proton charge radius puzzle The historical route to the proton charge radius (rp) is from elastic electron-proton scattering. In a completely complement...
The rainbow truncation of the quark Dyson–Schwinger equation is combined with the ladder Bethe–Salpeter equation for the dressed quark-photon vertex to study the low-momentum behavior of the pion electromagnetic form factor. With model gluon parameters previously fixed by the pion mass and decay constant, the pion charge radius rπ is found to be in excellent agreement with the data. When the of...
We have obtained a new limit on the electron neutrino effective charge radius from a new evaluation of the weak mixing angle by a combined fit of all electron(anti)neutrino electron elastic scattering measurements. Weak mixing angle is found to be sin θW = 0.259±0.025 in the low energy regime below 100 MeV. The electron neutrino charge radius squared is bounded to be in the range −0.13× 10 cm <...
The Σ− mean squared charge radius has been measured in the space-like Q range 0.035–0.105 GeV/c by elastic scattering of a Σ− beam off atomic electrons. The measurement was performed with the SELEX (E781) spectrometer using the Fermilab hyperon beam at a mean energy of 610 GeV/c. We obtain 〈r2 ch〉Σ− = (0.61 ± 0.12 (stat.) ± 0.09 (syst.)) fm. The proton and π− charge radii were measured as well ...
• Thompson modeled an atom as a sphere of radius ∼ 1Å (typical atom radius) lled uniformly by a cloud of positive charge Ze. Inside this cloud there are Z point-like electrons which sit still at their equilibrium positions determined by Coulomb forces. Under various circumstances, for example at by raising temperature, electrons can be excited into vibrating or orbiting motion. Such accelerated...
The growth processes of Tetragonal single crystals of solid solution (Cd0.6Zn0.32Mn0.08)3As2, space group P42/nmc, has been synthesized by Bridgman method. Conductivity and magnetoresistance of (Cd0.6Zn0.32Mn0.08)3As2 were measured in the range 1.6K to 300K and in magnetic field up to 25 T. Crossover from Mott variable-range-hopping conductivity mechanism close to helium temperatures. In this w...
The neutron is electrically neutral, but its substructure consists of charged quarks so it may have an internal charge distribution. In fact it is known to have a negative mean square charge radius (MSCR), the second moment of the radial charge density. In other words the neutron has a positive core and negative skin. In the first Born approximation the neutron MSCR can be simply related to the...
The charge radii of Σ and π have been determined by direct elastic scattering on shell electrons. The measurement was performed in the framework of the Selex (E781) charm hadroproduction experiment at Fermilab which employs a 600 GeV/c high-intensity Σ/π beam and a three-stage magnetic spectrometer covering 0.1 ≤ xF ≤ 1.0. Scattering angles and momenta of both hadron and electron were measured ...
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