ترغب بنشر مسار تعليمي؟ اضغط هنا

Unparticle Induced Baryon Number Violating Nucleon Decays

63   0   0.0 ( 0 )
 نشر من قبل Xiao-Gang He
 تاريخ النشر 2008
  مجال البحث فيزياء
والبحث باللغة English
 تأليف Xiao-Gang He




اسأل ChatGPT حول البحث

We study baryon number violating nucleon decays induced by unparticle interactions with the standard model particles. We find that the lowest dimension operators which cause nucleon decays can arise at dimension 6 + (d_s-3/2) with the unparticles being a spinor of dimension d_s=d_U +1/2. For scalar and vector unparticles of dimension d_U, the lowest order operatoers arise at 6+d_U and 7+d_U dimensions,respectively. Comparing the spinor unparticle induced n to O^s_U and experimental bound on invisible decay of a neutron from KamLAND, we find that the scale for unparticle physics is required to be larger than 10^{10} GeV for d_U < 2 if the couplings are set to be of order one. For scalar and vector unparticles, the dominant baryon number violating decay modes are nto bar u + O_U (O^mu_U) and p to e^+ + O_U (O^mu_U). The same experimental bound puts the scales for scalar and vector unparticle to be larger than 10^{7} and 10^{5} GeV for d_U <2 with couplings set to be of order one. Data on, p to e^+ invisible, puts similar constraints on unparticle interactions.

قيم البحث

اقرأ أيضاً

It is known that limits on baryon-violating nucleon decays do not, in general, imply corresponding suppression of $n - bar n$ transitions. In the context of a model with fermions propagating in higher dimensions, we investigate a related question, na mely the implications of limits on $Delta L=-1$ proton and bound neutron decays mediated by four-fermion operators for rates of nucleon decays mediated by $k$-fermion operators with $k =6$ and $k=8$. These include a variety of nucleon and dinucleon decays to dilepton and trilepton final states with $Delta L=-3, -2, 1$, and $2$. We carry out a low-energy effective field theory analysis of relevant operators for these decays and show that, in this extra-dimensional model, the rates for these decays are strongly suppressed and hence are in accord with experimental limits.
Recently there has been much interest in the use of single-jet mass and jet substructure to identify boosted particles decaying hadronically at the LHC. We develop these ideas to address the challenging case of a neutralino decaying to three quarks i n models with baryonic violation of R-parity. These decays have previously been found to be swamped by QCD backgrounds. We demonstrate for the first time that such a decay might be observed directly at the LHC with high significance, by exploiting characteristics of the scales at which its composite jet breaks up into subjets.
We consider effects of $n-bar n$ oscillations and resultant matter instability due to dinucleons decays. We point out that existing upper bounds on the rates for the dinucleon decays $nn to 2pi^0$, $nn to pi^+pi^-$, and $np to pi^+pi^0$ imply upper b ounds on the rates for dinucleon decays to dileptons $nn to e^+ e^-$, $nn to mu^+mu^-$, $nn to u_ell bar u_ell$, and $np to ell^+ u_ell$, where $ell=e, mu, tau$. We present estimates for these upper bounds. Our bounds are substantially stronger than corresponding limits from direct searches.
We search for lepton-number- and baryon-number-violating decays $tau^{-}tooverline{p}e^{+}e^{-}$, $pe^{-}e^{-}$, $overline{p}e^{+}mu^{-}$, $overline{p}e^{-}mu^{+}$, $overline{p}mu^{+}mu^{-}$, and $pmu^{-}mu^{-}$ using 921 fb$^{-1}$ of data, equivalen t to $(841pm12)times 10^6$ $tau^{+}tau^{-}$ events, recorded with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. In the absence of a signal, $90%$ confidence-level upper limits are set on the branching fractions of these decays in the range $(1.8$-$4.0)times 10^{-8}$. We set the worlds first limits on the first four channels and improve the existing limits by an order of magnitude for the last two channels.
Earlier estimates have argued that the baryon number violating scattering cross-section in the laboratory is exponentially small so it will never be observed, even for incoming 2-particle energy well above the sphaleron energy of 9 TeV. However, we a rgue in arXiv:1505.03690 that, due to the periodic nature of the sphaleron potential, the event rate for energies above the sphaleron energy may be high enough to be observed in the near future. That is, there is a discrepancy of about 70 orders of magnitude between the two estimates. Here we argue why and how the multi-sphaleron processes are crucial to the event rate estimate, a very important resonant tunneling property that has not been taken into account before. We also summarize the input assumptions and reasoning adopted in our estimate, when compared to the earlier estimates.
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