ترغب بنشر مسار تعليمي؟ اضغط هنا

Oscillation of heavy sterile neutrino in decay of $B to mu e pi$

44   0   0.0 ( 0 )
 نشر من قبل Gorazd Cvetic
 تاريخ النشر 2015
  مجال البحث
والبحث باللغة English




اسأل ChatGPT حول البحث

In a scenario with two almost mass degenerate heavy sterile Majorana neutrinos with a mass $sim 1$ GeV, we present the semileptonic decay widths of heavy charged pseudoscalars such as $B$ mesons, either lepton-number-violating ($B^{pm} to mu^{pm} e^{pm} pi^{mp}$), or lepton-number-conserving ($B^{pm} to mu^{pm} e^{mp} pi^{pm}$), mediated by such on-shell neutrinos. It had been explained in the literature that such decays may be eventually detected, and that they can present even detectable CP violation effects. In this work we point out that, in addition, such decays may present detectable effects of heavy neutrino oscillation, allowing us to extract the oscillation length and thus the heavy neutrino mass difference $Delta M_N$, as well as a CP-violating Majorana phase.

قيم البحث

اقرأ أيضاً

Distinguishing the Dirac and Majorana nature of neutrinos remains one of the most important tasks in neutrino physics. By assuming that the $tau^- to pi^- mu^- e^+ u$ (or $bar{ u}$) decay is resonantly enhanced by the exchange of an intermediate mas s sterile neutrino $N$, we show that the energy spectrum of emitted pions and muons can be used to easily distinguish between the Dirac and Majorana nature of $N$. This method takes advantage of the fact that the flavor of light neutrinos is not identified in the tau decay under consideration. We find that it is particularly advantageous, because of no competing background events, to search for $N$ in the mass range $m_e + m_{mu} leqslant m_N leqslant m_{mu} + m_{pi}$, where $m_X$ denotes the mass of particle $X in { e, mu, pi, N }$.
Heavy neutrinos were sought in pion decays $pi^+ rightarrow mu^+ u$ by examining the observed muon energy spectrum for extra peaks in addition to the expected peak for a massless neutrino. No evidence for heavy neutrinos was observed. Upper limits w ere set on the neutrino mixing matrix $|U_{mu i}|^2$ in the neutrino mass region of 15.7--33.8 MeV/c$^2$, improving on previous results by an order of magnitude.
A discovery of the rare decay $B^{+} rightarrow pi^{+} mu^{+} mu^{-}$ is presented. This decay is observed for the first time, with 5.2 $sigma$ significance. The observation is made using $pp$ collision data, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected with the LHCb detector. The measured branching fraction is (2.3 $pm$ 0.6 (stat.) $pm$ 0.1 (syst.))$times 10^{-8}$, and the ratio of the $B^{+} rightarrow pi^{+} mu^{+} mu^{-}$ and $B^{+} rightarrow K^{+} mu^{+} mu^{-}$ branching fractions is measured to be 0.053 $pm$ 0.014 (stat.) $pm$ 0.001 (syst.).
A high statistics data sample of the $K^{+}tomu^{+} u_{mu}$ decay was accumulated by the OKA experiment in 2012. The missing mass analysis was performed to search for the decay channel $K^{+}tomu^{+} u_{H}$ with a hypothetic stable heavy neutrino in the final state. The obtained missing mass spectrum does not show peaks which could be attributed to existence of stable heavy neutrinos in the mass range (220 $< m_{ u_{H}} <$ 375) MeV$/c^{2}$. As a result, we obtain upper limits on the branching ratio and on the value of the mixing element $|U_{mu H}|^{2}$.
In recent times, several discrepancies at the level of $(2-3)sigma$ have been observed in the decay processes mediated by flavour changing neutral current (FCNC) transitions $b to s ell^+ ell^-$, which may be considered as the smoking-gun signal of N ew Physics (NP). These intriguing hints of NP have attracted a lot of attention and many attempts are made to look for the possible NP signature in other related processes, which are mediated through the same quark-level transitions. In this work, we perform a comprehensive analysis of the FCNC decays of $B$ meson to axial vector mesons $ K_1(1270)$ and $ K_1(1400)$, which are admixture of the $1^3P_1$ and $1^1P_1$ states $K_{1A}$ and $K_{1B}$, in a model independent framework. Using the $ B to K_1$ form factors evaluated in the light cone sum rule approach, we investigate the rare exclusive semileptonic decays $ B to K_1(1270) mu^+ mu^-$ and $ B to K_1(1400) mu^+ mu^-$. Considering all the possible relevant operators for $b to s ell^+ ell^-$ transitions, we study their effects on various observables such as branching fractions, lepton flavor universality violating ratio ($R_{K_1})$, forward-backward asymmetries, and lepton polarization asymmetries of these processes. These results will not only enhance the theoretical understanding of the mixing angle but also serve as a good tool for probing New Physics.
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