Jones rondull lohoruroy of phvsim, unioersit,v michigan, am arbor, mi 48109, usa received 3 i august 198 i we consider the predictions for the weak mixing angle 0w and the scale m of unification in a. Pdf the substructure of the weak bosons and the weak. June 2018 slide 15 the total estimated uncertainty is 19. Of particular importance is the em coupling strength esince it. In this experiment you will count w and z mediated neutrino interactions, measure the relative couplings. The data correspond to integrated luminosities of 18. It is the angle by which spontaneous symmetry breaking rotates the original w 0 and b 0 vector boson plane, producing as a result the z 0 boson, and the photon. It is the angle by which spontaneous symmetry breaking rotates the original w 0 and b 0 vector boson plane, producing as a result the z 0 boson, and.
Measurement of the weak mixing angle with the drellyan process in protonproton collisions at the lhc. Is the tunable weak mixing angle weinberg angle of the. We include higher orders in the perturbative qcd expansion, as well as updated phenomenological and theoretical input, and obtain the result sin 2. Measurement of the weak mixing angle in moller scattering thesis by klejda bega in partial ful. Volume 237, issues 34, 22 march 1990, pages 537544. Z0 particles gives us the value of the weak mixing angle. Within the context of the standard model, theqe w measurement yields a determination of the weak mixing angle sin2. They can be used to extract values for the weak mixing angle, a fundamental parameter of the electroweak sector of the standard model. Experimentally, the weak mixing angle is measured very precisely with errors of order o10. Need to control impact on weak mixing angle at level well below 10. Pdf measurement of the weak mixing angle with the drell. The substructure of the weak bosons and the weak mixing angle. We report a preliminary result using 50% of the accumulated data sample for the rightleft parityviolating crosssection asymmetry apv in the elastic scattering of 45 and 48 gev polarized electron beams with unpolarized electrons in a liquid hydrogen target. Apart from providing a comprehensive test of the electroweak theory at the quantumloop level, such measurements allow indirect access to new.
Quantities with the superscript ferm do not contain the twoloop electroweak bosonic corrections, whereas those with the. We present a measurement of the fundamental parameter of the standard model, the weak mixing angle sin2. The mixing between zand y is what one naturally thinks of when speaking about the weak mixing angle. Weinberg angle derivation from discrete subgroups of su2. Thereasonforthediscrepancy is unknown but see 7, although one can surmise ei. From parity violation in ep scattering to the running of the weak mixing angle kyle shiells. Low energy measurements of the weak mixing angle request pdf. Why is the weak mixing angle in electroweak theory not consistent with the experimental result. The neutral higgs field circled breaks the electroweak symmetry and interacts with other particles to give them mass.
In this experiment you will count w and z mediated neutrino interactions, measure the relative couplings of w and z bosons and extract this parameter. Weak mixing angle in the thomson limit springerlink. A precision measurement of the weak mixing angle in m. The two most precise independent determinations of sin2 w di er by 3 their average is consistent with other electroweak measurements and with the theoretical prediction for the weak mixing angle assuming the 126 gev. A discussion based on the slac e158 moller scattering ee experiment. It relates for example the masses of the wboson and the zboson or the electric charge e with weak isospin g. The specific value of the angle is an unfixed parameter. The experiment utilizes a 48 gev longitudinally polarized electron beam on unpolarized atomic electrons in a target of liquid hydrogen to measure the parityviolating asymmetry apv in m. We report a measurement of the effective leptonic weak mixing angle sin2. Mar 30, 2018 we present a calculation of the weak mixing angle in the m s. William barter university of manchester weak mixing angle measurements hlhelhc. Measurement of the effective weak mixing angle in z events.
In the region m 12 900 gev, the two angles are separated from each other. The dispersion of points around the central value for m 12. Lowenergy measurements of the weak mixing angle 5 elegantly incorporated while weak neutral current e ects continued to be observed at about the predicted rate. In the standard model of particle physics, the cabibbokobayashimaskawa matrix, ckm matrix, quark mixing matrix, or km matrix is a unitary matrix which contains information on the strength of the flavourchanging weak interaction. For weak charged interactions cc quark flavour is not conserved, lepton universality for weak neutral interaction nc quark and lepton flavour are conserved useful hints photon only interacts electromagnetically neutrinos and z0 only interact weakly only quarks and gluons interact strongly if more than 1 possibility, faster reaction wins. W, is a parameter that describes the mixing of the gauge bosons related to the u 1 y and the third component of s u 2 l to give rise to the mass eigenstates of the. Pdf precise measurement of the weak mixing angle in neutrino. Its treelevel value has been measured with high precision at energies near the z0 pole. O y 0 b d d b 0 b d d t b t 0 b s s b 0 s s t b t significant contribution only from top loop m m v v 2 m2 o. It relates the masses of the w and z bosons and determines their relative couplings to matter. The pattern of weak isospin, t 3, and weak hypercharge, y w, of the known elementary particles, showing the electric charge, q, along the weak mixing angle. Bosonic corrections to the effective weak mixing angle at o. The main reference is precision measurement of the weak.
The usefulness of an effective weak mixing angle to parameterise the electroweak couplings of quarks and leptons measured at lep is discussed. It is used to determine the relationship between the w and z bosons masses. A precision measurement of the weak mixing angle in moller. Measurement of the effective leptonic weak mixing angle. Measurement of the e ective leptonic weak mixing angle using. For two generations of quarks, there are no cp violating phases, as shown by the counting of the previous section. Weak charged current changes lepton and quark flavours w boson transforms.
Weak mixing angle results at slc unt digital library. An ultraprecise measurement of the weak mixing angle. The e158 experiment at slac has made the first measurement of parity violation in electronelectron m\\oller scattering. Review of weak mixing angle results at slc and lep unt. Differences between pdfs from different global fits need to be understood. Measurement of the e ective leptonic weak mixing angle. Pdf precision measurement of the weak mixing angle in. The weak mixing angle and the search for new physics the weak mixing angle, denoted as q w, is an important parameter of the standard model. Lowenergy measurements of the weak mixing angle 7 abandoned, because its use induced large misleading o m2 tm 2 w radiative corrections to weak neutral current processes. That angle, understood in that sense defines the distribution of the vector current between 7 and z it surfaces in the fact that the em charge is proportional to sin 0, and that the vector part of the neutral current of fermions as coupling to. From parity violation in ep scattering to the running of. Measuring the weak mixing angle in the dune near detector. Measurement of the effective leptonic weak mixing angle using.
Pdf the authors present a highstatistics precision measurement of the weak mixing angle done at fermilab experiment e770 using the ratio. Table 3 higgs boson mass dependence of mw and sin2. The experiment utilizes a 48 gev longitudinally polarized electron beam on unpolarized atomic electrons in a target of liquid hydrogen to measure the parityviolating asymmetry apv in moller scattering. Pdf the substructure of the weak bosons and the weak mixing. Quark mixing and ckm matrix physikalisches institut. Key words weak neutral currents, weak mixing angle, precision. Little attention until thooft proved renormalizability 1971 weak neutral currents discovered 1972 neutrino scattering. Technically, it specifies the mismatch of quantum states of quarks when they propagate freely and when they take part in the weak interactions. The evolution of ew theory the weak mixing angle an ode to. W weinberg glashow or weak mixing angle most important electroweak parameter.
Twoloop electroweak contributions to the effective weak mixing angle, with a. The weinberg angle or weak mixing angle is a parameter in the weinbergsalam theory of the. The e ective leptonic weak mixing angle is measured to be 0. This angle is related to the probability that a neutrino will interact with matter to produce a scattered neutrino plus the remains of the target. The weak mixing angle is also known as weinberg angle. Measurement of the effective weak mixing angle in p. The effective leptonic weak mixing angle is measured to be 0. In partial fulfillment of the requirements for the degree of. Why is the weak mixing angle in electroweak theory not. Cabibbos solution consisted of postulating weak universality to resolve the first issue, along with a mixing angle. Pdf replicas that offer good descriptions of the observed afb. An ultraprecise measurement of the weak mixing angle using. If they assume that the minimal standard model provides a complete description of the quark and lepton couplings to the z boson, they find sinsup 2 thetasub wsup eff 0. Universal quantum corrections are absorbed into an effective, running weak mixing.
When i first saw the weinberg angle while sitting in the slac control room during e158, i wondered why the modern physics community named a 30 degree angle from basic trigonometry after a contemporary and then spent billions of dollars measuring. Apart from providing a comprehensive test of the electroweak theory at the quantumloop level, such measurements allow indirect. Pdf measurement of the weak mixing angle with the drellyan. On the definition of the weak mixing angle sciencedirect. Lowenergy measurements of the weak mixing angle annual. Pdf uncertainty is obtained as the standard deviation of the. The full supersymmetric one loop corrections to the effective weak mixing angle, experimentally determined in lep and sld experiments, are considered.
Measurement of the effective weak mixing angle in pp. The weak mixing angle is the central parameter of this unified theory. Lowenergy measurements of the weak mixing angle arxiv. The predictions of the mssm are discussed in the light of recent lep and sld precision data. Oct 27, 2017 when i first saw the weinberg angle while sitting in the slac control room during e158, i wondered why the modern physics community named a 30 degree angle from basic trigonometry after a contemporary and then spent billions of dollars measuring. W weak mixing weinberg angle w and z0 acquire mass via higgs mechanism. Within the standard model, weak neutral current amplitudes are functions of the weak mixing angle sin2 w. The weinberg angle or weak mixing angle is a parameter in the weinbergsalam theory of the electroweak interaction, part of the standard model of particle physics, and is usually denoted as. In some experiments for the weak mixing angle we get the values close to 0.
Measuring the weak mixing angle in the dune near detector complex. Measurement of the weak mixing angle in moller scattering. Universal quantum corrections are absorbed into an effective, running weak mixing angle. Current lhcb analysis has smaller pdf uncertainties than atlas, but a larger stat. The result would yield a measurement of the weak charge of the electron qe w to a fractional accuracy of 2. The weak mixing angle is one of the parameters of the standard model, our theory of particle interactions. Also, the radion can contribute to the s 2 process, but it turns out to be negligible. W is one of the parameter of the standard model specified in weinbergsalam theory of the electroweak interaction. Measurement of the weak mixing angle using the forward. Weak mixing angle at low energies jens erler1 and michael j. In particle physics, we describe interactions as exchanges of particles. In the standard model, the qe w measurement yields a determination of the weak mixing angle sin2. Measurement of the weak mixing angle using the forwardbackward.
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