We present a new extraction of the effective strong coupling constant αs,g1(Q2). The result agrees with a previous determination and extends the measurement of the low and high Q2 behavior of ...αs,g1(Q2) that was previously deduced from sum rules. In particular, it experimentally verifies the lack of Q2-dependence of αs,g1(Q2) in the low Q2 limit. This fact is necessary for application of the AdS/CFT correspondence to QCD calculations. We provide a parameterization of αs,g1(Q2) that can equivalently be used to parameterize the Q2-dependence of the generalized Gerasimov–Drell–Hearn and Bjorken sums.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We present a first attempt to experimentally extract an effective strong coupling constant that we define to be a low Q2 extension of a previous definition by S. Brodsky et al. following an initial ...work of G. Grunberg. Using Jefferson Lab data and sum rules, we establish its Q2-behavior over the complete Q2-range. The result is compared to effective coupling constants inferred from different processes and to calculations based on Schwinger–Dyson equations, hadron spectroscopy or lattice QCD. Although the connection between the experimentally extracted effective coupling constants and the calculations is not established it is interesting to note that their behaviors are similar.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The search for permanent electric dipole moments in non-degenerate systems has become a very active field of research in recent years. The experimental sensitivity has reached limits to probe physics ...beyond the Standard Model with high accuracy. This talk will review and summarize some of the ongoing efforts.
We report a new determination of the strange quark contribution to the proton's magnetic form factor at a four-momentum transfer Q2=0.1 (GeV/c)2 from parity-violating e–p elastic scattering. The ...result uses a revised analysis of data from the SAMPLE experiment which was carried out at the MIT-Bates Laboratory. The data are combined with a calculation of the proton's axial form factor GeA to determine the strange form factor GsM(Q2=0.1)=0.37±0.20±0.26±0.07. The extrapolation of GsM to its Q2=0 limit and comparison with calculations is also discussed.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The radioactive radium-225 (Ra225) atom is a favorable case to search for a permanent electric dipole moment. Because of its strong nuclear octupole deformation and large atomic mass, Ra225 is ...particularly sensitive to interactions in the nuclear medium that violate both time-reversal symmetry and parity. We have developed a cold-atom technique to study the spin precession of Ra225 atoms held in an optical dipole trap, and demonstrated the principle of this method by completing the first measurement of its atomic electric dipole moment, reaching an upper limit of d(Ra225) 25.0x10-22 e cm (95% confidence).
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Methods for optical calibration of the BigBite hadron spectrometer Mihovilovič, M.; Širca, S.; Allada, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2012, Volume:
686
Journal Article
Peer reviewed
Open access
The techniques for the optical calibration of Jefferson Lab's large-acceptance magnetic hadron spectrometer, BigBite, have been examined. The most consistent and stable results were obtained using a ...method based on singular value decomposition. In spite of the complexity of the optics, the particles' positions and momenta at the target have been precisely reconstructed from the coordinates measured in the detectors by means of a single back-tracing matrix. The technique is applicable to any similar magnetic spectrometer and any particle type. For 0.55GeV/c protons, we have established a vertex resolution of 1.2cm, angular resolutions of 7mrad and 13mrad (in-plane and out-of-plane, respectively), and a relative momentum resolution of 1.6%.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
High precision photon flux determination for photon tagging experiments Teymurazyan, A.; Ahmidouch, A.; Ambrozewicz, P. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2014, Volume:
767, Issue:
C
Journal Article
Peer reviewed
The Jefferson Laboratory PrimEx Collaboration has developed and implemented a method to control the tagged photon flux in photoproduction experiments at the 1% level over the photon energy range from ...4.9 to 5.5GeV. This method has been successfully implemented in a high precision measurement of the neutral pion lifetime. Here, we outline the experimental equipment and the analysis techniques used to accomplish this. These include the use of a total absorption counter for absolute flux calibration, a pair spectrometer for online relative flux monitoring, and a new method for post-bremsstrahlung electron counting.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
We present experimental results of the first high-precision test of quark-hadron duality in the spin-structure function g_{1} of the neutron and 3He using a polarized 3He target in the ...four-momentum-transfer-squared range from 0.7 to 4.0 (GeV/c);{2}. Global duality is observed for the spin-structure function g_{1} down to at least Q;{2}=1.8 (GeV/c);{2} in both targets. We have also formed the photon-nucleon asymmetry A1 in the resonance region for 3He and found no strong Q2 dependence above 2.2 (GeV/c);{2}.
Full text
Available for:
CMK, CTK, FMFMET, IJS, NUK, PNG, UM
PDF
