Electrons, new physics, and the future of parity-violation

There is no question that contemporary western civilization has beendominant in the field of science since the Renaissance. Western scientificsuperiority is not limited to specific scientific disciplines, but is rather anovetall scientific domination covering both the so-called exact and thehuman-social sciences. Western science is the primary reference for specialistsin such ateas as physics, chemistry, biology, medicine, economics,psychology, and sociology. It is in this sense that Third World underdevelopmentis not only economic, social, and industrial; it also suffersfrom scientific-cultutal underdevelopment, or what we call "The OtherUnderdevelopment" (Dhaouadi 1988).The imptessive progress of western science since Newton and Descartesdoes not meari, however, that it has everything tight or perfect. Infact, its flaws ate becoming mote visible. In the last few decades, westernscience has begun to experience a shift from what is called classical scienceto new science. Classical science was associated with the celestialmechanics of Copernicus, Kepler, Newton, the new physics of Galileo,and the philosophy of Descartes. Descartes introduced a radical divisionbetween mind and matter, while Newton and his fellows presented a newscience that looked at the world as a kind of giant clock The laws of thisworld were time-reversible, for it was held that there was no differencebetween past and future. As the laws were deterministic, both the pastand the future could be predicted once the present was known.The vision of the emerging new science tends to heal the division betweenmatter and spirit and to do away with the mechanical dimension ...

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Searching for Z′ bosons at the P2 experiment

Journal of High Energy Physics ◽

10.1007/jhep06(2021)039 ◽

2021 ◽

Vol 2021 (6) ◽

Author(s):

P. S. Bhupal Dev ◽

Werner Rodejohann ◽

Xun-Jie Xu ◽

Yongchao Zhang

Keyword(s):

Parity Violation ◽

Z Bosons ◽

Gauge Coupling ◽

New Physics ◽

Polarized Electrons ◽

Mixing Angles ◽

Charge Assignment ◽

Wide Range ◽

Discovery Potential ◽

Left And Right

Abstract The P2 experiment aims at high-precision measurements of the parity-violating asymmetry in elastic electron-proton and electron-12C scatterings with longitudinally polarized electrons. We discuss here the sensitivity of P2 to new physics mediated by an additional neutral gauge boson Z′ of a new U(1)′ gauge symmetry. If the charge assignment of the U(1)′ is chiral, i.e., left- and right-handed fermions have different charges under U(1)′, additional parity-violation is induced directly. On the other hand, if the U(1)′ has a non-chiral charge assignment, additional parity-violation can be induced via mass or kinetic Z-Z′ mixing. By comparing the P2 sensitivity to existing constraints, we show that in both cases P2 has discovery potential over a wide range of Z′ mass. In particular, for chiral models, the P2 experiment can probe gauge couplings at the order of 10−5 when the Z′ boson is light, and heavy Z′ bosons up to 79 (90) TeV in the proton (12C) mode. For non-chiral models with mass mixing, the P2 experiment is sensitive to mass mixing angles smaller than roughly 10−4, depending on model details and gauge coupling magnitude.

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FROM HADRONIC PARITY VIOLATION TO PARITY-VIOLATING ELECTRON SCATTERING AND TESTS OF THE STANDARD MODEL

Modern Physics Letters A ◽

10.1142/s0217732308027643 ◽

2008 ◽

Vol 23 (17n20) ◽

pp. 1266-1277 ◽

Cited By ~ 1

Author(s):

WILLEM T. H. VAN OERS

Keyword(s):

Standard Model ◽

Electron Scattering ◽

Parity Violation ◽

New Physics ◽

Theoretical Interpretation ◽

Weak Mixing Angle ◽

Weak Mixing ◽

Mixing Angle ◽

The Standard Model ◽

Analyzing Power

Searches for parity violation in hadronic systems started soon after the evidence for parity violation in β-decay of 60 Co was presented by Madame Chien-Shiung Wu and in π and μ decay by Leon Lederman in 1957. The early searches for parity violation in hadronic systems did not reach the sensitivity required and only after technological advances in later years was parity violation unambiguously established. Within the meson-exchange description of the strong interaction, theory and experiment meet in a set of seven weak meson-nucleon coupling constants. Even today, after almost five decades, the determination of the seven weak meson-nucleon couplings is incomplete. Parity violation in nuclear systems is rather complex due to the intricacies of QCD. More straight forward in terms of interpretation are measurements of the proton-proton parity-violating analyzing power (normalized differences in scattering yields for positive and negative helicity incident beams), for which there exist three precision experiments (at 13.6, at 45, and 221 MeV). To-date, there are better possibilities for theoretical interpretation using effective field theory approaches. The situation with regard to the measurement of the parity-violating analyzing power or asymmetry in polarized electron scattering is quite different. Although the original measurements were intended to determine the electro-weak mixing angle, with the current knowledge of the electro-weak interaction and the great precision with which electro-weak radiative corrections can be calculated, the emphasis has been to study the structure of the nucleon, and in particular the strangeness content of the nucleon. A whole series of experiments (the SAMPLE experiment at MIT-Bates, the G0 experiment and HAPPEX experiments at Jefferson Laboratory (JLab), and the PVA4 experiment at MAMI) have indicated that the strange quark contributions to the charge and magnetization distributions of the nucleon are tiny. These measurements if extrapolated to zero degrees and zero momentum transfer have also provided a factor five improvement in the knowledge of the neutral weak couplings to the quarks. Choosing appropriate kinematics in parity-violating electron-proton scattering permits nucleon structure effects on the measured analyzing power to be precisely controlled. Consequently, a precise measurement of the ‘running’ of sin 2θw or the electro-weak mixing angle has become within reach. The [Formula: see text] experiment at Jefferson Laboratory is to measure this quantity to a precision of about 4%. This will either establish conformity with the Standard Model of quarks and leptons or point to New Physics as the Standard Model must be encompassed in a more general theory required, for instance, by a convergence of the three couplings (strong, electromagnetic, and weak) to a common value at the GUT scale. The upgrade of CEBAF at Jefferson Laboratory to 12 GeV, will allow a new measurement of sin 2θW in parity-violating electron-electron scattering with an improved precision to the current better measurement (the SLAC E158 experiment) of the ‘running’ of sin 2θW away from the Z0 pole. Preliminary design studies of such an experiment show that a precision comparable to the most precise individual measurements at the Z0 pole (to about ±0.00025) can be reached. The result of this experiment will be rather complementary to the [Formula: see text] experiment in terms of sensitivity to New Physics.

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