ترغب بنشر مسار تعليمي؟ اضغط هنا

First Test of Lorentz Invariance in the Weak Decay of Polarized Nuclei

262   0   0.0 ( 0 )
 نشر من قبل A. Sytema
 تاريخ النشر 2013
  مجال البحث
والبحث باللغة English




اسأل ChatGPT حول البحث

A new test of Lorentz invariance in the weak interactions has been made by searching for variations in the decay rate of spin-polarized 20Na nuclei. This test is unique to Gamow-Teller transitions, as was shown in the framework of a recently developed theory that assumes a Lorentz symmetry breaking background field of tensor nature. The nuclear spins were polarized in the up and down direction, putting a limit on the amplitude of sidereal variations of the form |(Gamma_{up} - Gamma_{down})| / (Gamma_{up} + Gamma_{down}) < 3 * 10^{-3}. This measurement shows a possible route toward a more detailed testing of Lorentz symmetry in weak interactions.



قيم البحث

اقرأ أيضاً

We search for a dependence of the lifetime of $^{20}text{Na}$ nuclei on the nuclear spin direction. Such a directional dependence would be evidence for Lorentz-invariance violation in weak interactions. A difference in lifetime between nuclei that ar e polarized in the east and west direction is searched for. This difference is maximally sensitive to the rotation of the Earth, while the sidereal dependence is free from most systematic errors. The experiment sets a limit of $2times 10^{-4}$ at 90 % C.L. on the amplitude of the sidereal variation of the relative lifetime differences, an improvement by a factor 15 compared to an earlier result.
78 - H. P. Mumm , A. Garcia , L. Grout 2004
We describe an apparatus used to measure the triple-correlation term (D hat{sigma}_ncdot p_etimes p_ u) in the beta-decay of polarized neutrons. The D-coefficient is sensitive to possible violations of time reversal invariance. The detector has an oc tagonal symmetry that optimizes electron-proton coincidence rates and reduces systematic effects. A beam of longitudinally polarized cold neutrons passes through the detector chamber, where a small fraction beta-decay. The final-state protons are accelerated and focused onto arrays of cooled semiconductor diodes, while the coincident electrons are detected using panels of plastic scintillator. Details regarding the design and performance of the proton detectors, beta detectors and the electronics used in the data collection system are presented. The neutron beam characteristics, the spin-transport magnetic fields, and polarization measurements are also described.
168 - I. Altarev , C. A. Baker , G. Ban 2009
A clock comparison experiment, analyzing the ratio of spin precession frequencies of stored ultracold neutrons and $^{199}$Hg atoms is reported. %57 No daily variation of this ratio could be found, from which is set an upper limit on the Lorentz inva riance violating cosmic anisotropy field $b_{bot} < 2 times 10^{-20} {rm eV}$ (95% C.L.). This is the first limit for the free neutron. This result is also interpreted as a direct limit on the gravitational dipole moment of the neutron $|g_n| < 0.3 $eV/$c^2$ m from a spin-dependent interaction with the Sun. Analyzing the gravitational interaction with the Earth, based on previous data, yields a more stringent limit $|g_n| < 3 times 10^{-4} $eV/$c^2 $m.
A novel test of time-reversal invariance in proton-deuteron scattering is planned as an internal target transmission experiment at the cooler synchrotron COSY. The P-even, T-odd observable is the polarization correlation $A_{y,xz}$ of the total cross section measured using a polarized internal proton beam (polarization $p_y$) and an internal polarized deuterium target (tensor polarization $p_{xz}$). Measuring this observable is a true null test of time reversal invariance and therefore allows to reach a high accuracy. Sufficient luminosity can be obtained using a window-less storage cell placed on the axis of the proton beam. Tensor polarized atoms are produced in an atomic beam source based on Stern-Gerlach separation in permanent sextupole magnets and adiabatic high frequency transitions. The total cross section correlation is measured by monitoring the beam transmission in the COSY storage ring mode of operation. The proton beam momentum will be in the range 2-3 GeV/c. This momentum is ideally suited to test possible short range contributions, i.e. natural parity charged $rho$-type and unnatural parity $a_1$-type meson exchange contributions. The feasibility of the experiment, systematic errors and the expected accuracy are discussed.
We propose a way to recover Lorentz invariance of the perturbative S matrix in the Discrete Light-Cone Quantization (DLCQ) in the continuum limit without spoiling the trivial vacuum.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا