ترغب بنشر مسار تعليمي؟ اضغط هنا

Charge asymmetry in electron/positron energy loss in nuclear Bremsstrahlung

41   0   0.0 ( 0 )
 نشر من قبل Roman Nikolaevich Lee
 تاريخ النشر 2021
  مجال البحث
والبحث باللغة English




اسأل ChatGPT حول البحث

We calculate the leading Coulomb correction to the energy loss in the electron-nucleus Bremsstrahlung for arbitrary energy of the incoming particle. This correction determines the charge asymmetry, i.e., the difference of electron and positron energy loss. The result is presented in terms of the classical polylogarithms $mathrm{Li}_2$ and $mathrm{Li}_3$. We use modern multiloop methods based on the IBP reduction and on the differential equations for master integrals. We provide both the threshold and the high-energy asymptotics of the found asymmetry and compare them with the available results.

قيم البحث

اقرأ أيضاً

We calculate the rate of collisional decay of the axial charge in an ultrarelativistic electron-positron plasma, also known as the chirality flipping rate. We find that contrary to the existing estimates, the chirality flipping rate appears already i n the first order in the fine-structure constant $alpha$ and is therefore orders of magnitude greater than previously believed. The main channels for the rapid relaxation of the axial charge are the collinear emission of a weakly damped photon and the Compton scattering. The latter contributes to the $mathcal{O}(alpha)$ result because of the infrared divergence in its cross section, which is regularized on the soft scale $sim eT$ due to the thermal corrections. Our results are important for the description of the early Universe processes (such as leptogenesis or magnetogenesis) that affect differently left- and right-chiral fermions of the Standard Model, as discussed in more details in the companion Letter.
There has been much interest in the blowout regime of plasma wakefield acceleration (PWFA), which features ultra-high fields and nonlinear plasma motion. Using an exact analysis, we examine here a fundamental limit of nonlinear PWFA excitation, by an infinitesimally short, relativistic electron beam. The beam energy loss in this case is shown to be linear in charge even for nonlinear plasma response, where a normalized, unitless charge exceeds unity. The physical basis for this effect is discussed, as are deviations from linear behavior observed in simulations with finite length beams.
The bottom quark forward-backward asymmetry $A_{rm{FB}}$ is a key observable in electron-positron collisions at the $Z^{0}$ peak. In this paper, we employ the Principle of Maximum Conformality (PMC) to fix the $alpha_s$-running behavior of the next-t o-next-to-leading order QCD corrections to $A_{rm{FB}}$. The resulting PMC scale for this $A_{rm{FB}}$ is an order of magnitude smaller than the conventional choice $mu_r=M_Z$. This scale has the physically reasonable behavior and reflects the virtuality of its QCD dynamics, which is independent to the choice of renormalization scale. Our analyses show that the effective momentum flow for the bottom quark forward-backward asymmetry should be $mu_rll M_Z$ other than the conventionally suggested $mu_r=M_Z$. Moreover, the convergence of perturbative QCD series for $A_{rm{FB}}$ is greatly improved using the PMC. Our prediction for the bare bottom quark forward-backward asymmetry is refined to be $A^{0,b}_{rm FB}=0.1004pm0.0016$, which diminishes the well known tension between the experimental determination for this (pseudo) observable and the respective Standard Model fit to $2.1sigma$.
We review in some detail the QCD corrections to the measurement of the forward-backward charge asymmetry of heavy quarks in the $mathrm{e^+e^-rightarrow Qoverline{Q}(g)}$ process at the Z pole. We show that the size of these corrections can be reduce d by an order of magnitude by using simple cuts on jet acollinearity. Such a reduction is expected to lead to systematic uncertainties at the $Delta mathrm{A_{FB}^{0,Q}} approx 10^{-4}$ level, opening up the path to high precision electroweak measurements with heavy flavors at future high luminosity $mathrm{e^+e^-}$ colliders like the FCC-ee.
Process of muon (pion) pair production with small invariant mass in the electron-positron high-energy annihilation, accompanied by emission of hard photon at large angles, is considered. We find that the Dell-Yan picture for differential cross sectio n is valid in the charge-even experimental set-up. Radiative corrections both for electron block and for final state block are taken into account.
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