ترغب بنشر مسار تعليمي؟ اضغط هنا

Probing Nucleon Strangeness with Neutrinos: Nuclear Model Dependences

58   0   0.0 ( 0 )
 نشر من قبل Maria Barbaro
 تاريخ النشر 1996
  مجال البحث
والبحث باللغة English
 تأليف M.B. Barbaro




اسأل ChatGPT حول البحث

The extraction of the nucleons strangeness axial charge, Delta_s, from inclusive, quasielastic neutral current neutrino cross sections is studied within the framework of the plane-wave impulse approximation. We find that the value of Delta_s can depend significantly on the choice of nuclear model used in analyzing the quasielastic cross section. This model-dependence may be reduced by one order of magnitude when Delta_s is extracted from the ratio of total proton to neutron yields. We apply this analysis to the interpretation of low-energy neutrino cross sections and arrive at a nuclear theory uncertainty of plus/minus 0.03 on the value of Delta_s expected to be determined from the ratio of proton and neutron yields measured by the LSND collaboration. This error compares favorably with estimates of the SU(3)-breaking uncertainty in the value of Delta_s extracted from inclusive, polarized deep-inelastic structure function measurements. We also point out several general features of the quasielastic neutral current neutrino cross section and compare them with the analogous features in inclusive, quasielastic electron scattering.



قيم البحث

اقرأ أيضاً

112 - T. J. Hobbs , Mary Alberg , 2014
Determining the nonperturbative $sbar{s}$ content of the nucleon has attracted considerable interest and been the subject of numerous experimental searches. These measurements used a variety of reactions and place important limits on the vector form factors observed in parity-violating (PV) elastic scattering and the parton distributions determined by deep inelastic scattering (DIS). In spite of this progress, attempts to relate information obtained from elastic and DIS experiments have been sparse. To ameliorate this situation, we develop an interpolating model using light-front wave functions capable of computing both DIS and elastic observables. This framework is used to show that existing knowledge of DIS places significant restrictions on our wave functions. The result is that the predicted effects of nucleon strangeness on elastic observables are much smaller than those tolerated by direct fits to PV elastic scattering data alone. Using our model, we find $-0.024 le mu_s le 0.035$, and $-0.137 le rho^D_s le 0.081$ for the strange contributions to the nucleon magnetic moment and charge radius. The model we develop also independently predicts the nucleons strange spin content $Delta s$ and scalar density $langle N| bar{s}s | N rangle$, and for these we find agreement with previous determinations.
The Omega-bar/Omega ratio originating from string decays is predicted to be larger than unity in proton-proton interaction at SPS energies. The anti-omega dominance increases with decreasing beam energy. This surprising behavior is caused by the comb inatorics of quark-antiquark production in small and low-mass strings. Since this behavior is not found in a statistical description of hadron production in proton-proton collisions, it may serve as a key observable to probe the hadronization mechanism in such collisions.
We report on a novel ab initio approach for nuclear few- and many-body systems with strangeness. Recently, we developed a relevant no-core shell model technique which we successfully applied in first calculations of lightest $Lambda$ hypernuclei. The use of a translationally invariant finite harmonic oscillator basis allows us to employ large model spaces, compared to traditional shell model calculations, and use realistic nucleon-nucleon and nucleon-hyperon interactions (such as those derived from EFT). We discuss formal aspects of the methodology, show first demonstrative results for ${}_{Lambda}^3$H, ${}_{Lambda}^4$H and ${}^4_Lambda$He, and give outlook.
Kaon production in pion-nucleon collisions in nuclear matter is studied in the resonance model. To evaluate the in-medium modification of the reaction amplitude as a function of the baryonic density we introduce relativistic, mean-field potentials fo r the initial, final and intermediate mesonic and baryonic states. These vector and scalar potentials were calculated using the quark-meson coupling (QMC) model. The in-medium kaon production cross sections in pion-nucleon interactions for reaction channels with $Lambda$ and $Sigma$ hyperons in the final state were calculated at the baryonic densities appropriate to relativistic heavy ion collisions. Contrary to earlier work which has not allowed for the change of the cross section in medium, we find that the data for kaon production are consistent with a repulsive $K^+$-nucleus potential.
A linear correlation is found between the magnitude of nucleon-nucleon short-range correlations and the nuclear binding energy per nucleon with pairing energy removed. By using this relation, the strengths of nucleon-nucleon short-range correlations of some unmeasured nuclei are predicted. Discussions on nucleon-nucleon pairing energy and nucleon-nucleon short-range correlations are made. The found nuclear dependence of nucleon-nucleon short-range correlations may shed some lights on the short-range structure of nucleus.
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