اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدTheoretical Analysis of Antineutron-Nucleus Data needed for Antineutron Mirrors in Neutron-Antineutron Oscillation Experiments
195
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
The values of the antineutron-nucleus scattering lengths, and in particular their imaginary parts, are needed to evaluate the feasibility of using neutron mirrors in laboratory experiments to search for neutron-antineutron oscillations. We analyze existing experimental and theoretical constraints on these values with emphasis on low $A$ nuclei and use the results to suggest materials for the neutron/antineutron guide and to evaluate the systematic uncertainties in estimating the neutron-antineutron oscillation time. As an example we discuss a scenario for a future neutron-antineutron oscillation experiment proposed for the European Spallation Source. We also suggest future experiments which can provide a better determination of the values of antineutron-nuclei scattering lengths.
قيم البحث
اقرأ أيضاً
We consider the possibility of neutron-antineutron ($n-bar n$) conversion, in which the change of a neutron into an antineutron is mediated by an external source, as can occur in a scattering process. We develop the connections between $n-{bar n}$ co
nversion and $n-{bar n}$ oscillation, in which a neutron spontaneously tranforms into an antineutron, noting that if $n-{bar n}$ oscillation occurs in a theory with B-L violation, then $n-{bar n}$ conversion can occur also. We show how an experimental limit on $n-{bar n}$ conversion could connect concretely to a limit on $n-{bar n}$ oscillation, and vice versa, using effective field theory techniques and baryon matrix elements computed in the M.I.T. bag model.
Two-loop anomalous dimensions and one-loop renormalization scheme matching factors are calculated for six-quark operators responsible for neutron-antineutron transitions. When combined with lattice QCD determinations of the matrix elements of these o
perators, our results can be used to reliably predict the neutron-antineutron vacuum transition time, $tau_{nbar{n}}$, in terms of basic parameters of baryon-number violating beyond-the-Standard-Model theories. The operators are classified by their chiral transformation properties, and a basis in which there is no operator mixing due to strong interactions is identified. Operator projectors that are required for non-perturbative renormalization of the corresponding lattice QCD six-quark operator matrix elements are constructed. A complete calculation of $delta m = 1/tau_{nbar{n}}$ in a particular beyond-the-Standard-Model theory is presented as an example to demonstrate how operator renormalization and results from lattice QCD are combined with experimental bounds on $delta m$ to constrain the scale of new baryon-number violating physics. At the present computationally accessible lattice QCD matching scale of $sim$ 2 GeV, the next-to-next-to-leading-order effects calculated in this work correct the leading-order plus next-to-leading-order $delta m$ predictions of beyond-the-Standard-Model theories by $< 26%$. Next-to-next-to-next-to-leading-order effects provide additional unknown corrections to predictions of $delta m$ that are estimated to be $< 7%$.
We point out that if neutron--antineutron oscillation is observed in a free neutron oscillation experiment, it will put an upper limit on the strengths of Lorentz invariance violating (LIV) mass operators for neutrons at the level of $10^{-23}$ GeV o
r so, which would be the most stringent LIV limit for neutrons. We also study constraints on $Delta B=2$ LIV operators and find that for one particular operator degaussing is not necessary to obtain a visible signal. We also note that observation of $n-bar{n}$ oscillation signal in the nucleon decay search experiment involving nuclei does not lead to any limit on LIV operators since the nuclear potential difference between neutron and antineutrons will mask any Lorentz violating effect.
Experimental observation of nucleon instability is one of the missing key components required for the explanation of baryon asymmetry of the universe. Proton decays with the modes and rates predicted by(B-L)-conserving schemes of Grand Unification ar
e not observed experimentally. There are reasons to believe that (B-L) might not be conserved in nature, thus leading to the nucleon decay into lepton+(X) and to phenomena such as Majorana masses of neutrinos, neutrinoless double-beta decays, and most spectacularly to the transitions of neutron to anti-neutron. The energy scale where (B-L) violation takes place cannot be predicted by theory and therefore has to be explored by experiments. Different experimental approaches to searching for (B-L)-violating transition of neutron to antineutron are discussed in this paper. Most powerful search for neutron to antineutron transitions can be performed in a new reactor-based experiment at HFIR reactor (ORNL) where sensitivity can be >1,000 times higher than in the previous experiments.
This paper summarizes the relevant theoretical developments, outlines some ideas to improve experimental searches for free neutron-antineutron oscillations, and suggests avenues for future improvement in the experimental sensitivity.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
