ترغب بنشر مسار تعليمي؟ اضغط هنا

Mixing Angle of Hadrons in QCD: A New View

44   0   0.0 ( 0 )
 نشر من قبل Altug Ozpineci
 تاريخ النشر 2010
  مجال البحث
والبحث باللغة English




اسأل ChatGPT حول البحث

A new method for calculation of the mixing angle between the hadrons within QCD sum rules is proposed. In this method, the mixing is expressed in terms of quark and gluon degrees of freedom. As an application, the detailed calculation of the mixing angle between heavy cascade baryons Xi_Q and Xi_Q, Q=c,~b is presented and it is found that the mixing angle between Xi_b (Xi_c) and Xi_b (Xi_c) is given by theta_b = 6.4^circ pm 1.8 ^circ (theta_c = 5.5^circ pm 1.8^circ).

قيم البحث

اقرأ أيضاً

88 - M. Woods 2004
The E158 experiment at SLAC has made the first measurement of parity violation in electron-electron (Moller) scattering. We report a preliminary result using 50% of the accumulated data sample for the right-left parity-violating cross-section asymmet ry (APV) in the elastic scattering of 45 and 48 GeV polarized electron beams with unpolarized electrons in a liquid hydrogen target. We find APV = (-160 +- 21 (stat.) +- 17 (syst.)) parts per billion, with a significance of 6.3sigma for observing parity violation. In the context of the Standard Model, this yields a measurement of the weak mixing angle, sin^2(thetaW-MSBAR)(Q^2 = 0.026 GeV^2) = 0.2379 +- 0.0016 (stat.) +- 0.0013 (syst.). We also present preliminary results for the first observation of a single-spin transverse asymmetry in Moller scattering.
The $Sigma$--$Lambda$ mixing angle is calculated in framework of the QCD sum rules. We find that our prediction for the mixing angle is $(1.00pm 0.15)^0$ which is in good agreement with the quark model prediction, and approximately two times larger than the recent lattice QCD calculations.
The propagation of colored quarks through strongly interacting systems, and their subsequent evolution into color-singlet hadrons, are phenomena that showcase unique facets of Quantum Chromodynamics (QCD). Medium-stimulated gluon bremsstrahlung, a fu ndamental QCD process, induces broadening of the transverse momentum of the parton, and creates partonic energy loss manifesting itself in experimental observables that are accessible in high energy interactions in hot and cold systems. The formation of hadrons, which is the dynamical enforcement of the QCD confinement principle, is very poorly understood on the basis of fundamental theory, although detailed models such as the Lund string model or cluster hadronization models can generally be tuned to capture the main features of hadronic final states. With the advent of the technical capability to study hadronic final states from lepton scattering with good particle identification and at high luminosity, a new opportunity has appeared. Study of the characteristics of parton propagation and hadron formation as they unfold within atomic nuclei are now being used to understand the coherence and spatial features of these processes and to refine new experimental tools that will be used in future experiments. Fixed-target data on nuclei with lepton and hadron beams, and collider experiments involving nuclei, all make essential contact with these topics and they elucidate different aspects of these same themes. In this paper, a survey of the most relevant recent data and its potential interpretation will be followed by descriptions of planned experiments at Jefferson Lab following the completion of the 12 GeV upgrade, and feasible measurements at a future Electron-Ion Collider.
98 - Paul Hoyer 2021
Bound state perturbation theory is well established for QED atoms. Today the hyperfine splitting of Positronium is known to $O(alpha^7logalpha)$. Whereas standard expansions of scattering amplitudes start from free states, bound states are expanded a round eigenstates of the Hamiltonian including a binding potential. The eigenstate wave functions have all powers of $alpha$, requiring a choice in the ordering of the perturbative expansion. Temporal $(A^0=0)$ gauge permits an expansion starting from valence Fock states, bound by their instantaneous gauge field. This formulation is applicable in any frame and seems promising even for hadrons in QCD. The $O(alpha_s^0)$ confining potential is determined (up to a universal scale) by a homogeneous solution of Gauss law.
We have obtained a new limit on the electron neutrino effective charge radius from a new evaluation of the weak mixing angle by a combined fit of all electron-(anti)neutrino electron elastic scattering measurements. Weak mixing angle is found to be s in^2 theta_W=0.259 pm 0.025 in the low energy regime below 100 MeV. The electron neutrino charge radius squared is bounded to be in the range -0.13 10^-32 cm^2 < r^2 < 3.32 10^-32 cm^2 at 90 % C.L. Both results improve previously published analyses. We also discuss perspectives of future experiments to improve these constraints.
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