اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدLimit on the production of a light vector gauge boson in phi meson decays with the KLOE detector
222
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
We present a new limit on the production of a light dark-force mediator with the KLOE detector at DAPHNE. This boson, called U, has been searched for in the decay phi --> eta U, U --> e+ e-, analyzing the decay eta --> pi0 pi0 pi0 in a data sample of 1.7 fb-1. No structures are observed in the e+e- invariant mass distribution over the background. This search is combined with a previous result obtained from the decay eta --> pi+ pi- pi0, increasing the sensitivity. We set an upper limit at 90% C.L. on the ratio between the U boson coupling constant and the fine structure constant of alpha/alpha < 1.7x10^-5 for 30<M_U<400 MeV and alpha/alpha < 8x10^-6 for the sub-region 50<M_U<210 MeV. This result assumes the Vector Meson Dominance expectations for the phietagamma^* transition form factor. The dependence of this limit on the transition form factor has also been studied.
قيم البحث
اقرأ أيضاً
We have searched for a light vector boson $U$, the possible carrier of a dark force, with the KLOE detector at the DA$Phi$NE epm collider, motivated by astrophysical evidence for the presence of dark matter in the universe. Using epm collisions colle
cted with an integrated luminosity of $239.3$~pb$^{-1}$, we look for a dimuon mass peak in the reaction epmto$mu^+ mu^-$gam, corresponding to the decay $Utomu^+mu^-$. We find no evidence for a $U$ vector boson signal. We set a 90% CL upper limit for the mixing parameter squared between the photon and the $U$ boson of 1.6$times$10$^{-5}$ to 8.6$times$10$^{-7}$ for the mass region $520<m_{rm U}<980$ MeV.
We have studied the e+e- -> omegapi0 cross section in the sqrt(s) interval 1000-1030 MeV using the pi+pi-pi0pi0 and pi0pi0gamma final states with a sample of ~600 pb^-1 collected with the KLOE detector at DAFNE. By fitting the observed interference p
attern around M_phi for both final states, we extract the ratio of the decay widths Gamma(omega->pi0gamma)/Gamma(omega->pi+pi-pi0) = 0.0897 +- 0.0016 and derive the branching fractions BR(omega -> pi+pi-pi0)= (90.24 +- 0.19)%, BR(omega -> pi0gamma) = (8.09 +- 0.14)%. The parameters describing the e+e- -> omegapi0 reaction around M_phi are also used to extract the branching fraction for the OZI and G-parity violating phi -> omegapi0 decay: BR(phi->omegapi0) = (4.4 +- 0.6)x10^-5.
The recent interest in a light gauge boson in the framework of an extra U(1) symmetry motivates searches in the mass range below 1 GeV. We present a search for such a particle, the dark photon, in ${rm e^+ e^-}rightarrow {rm U}gamma$, U$rightarrow
pi^+pi^-$ based on 28 million $mathrm{e^+ e^-} rightarrow pi^+ pi^-gamma$ events collected at DA$Phi$NE by the KLOE experiment. The $pi^+ pi^-$ production by initial-state radiation compensates for a loss of sensitivity of previous KLOE ${rm U} rightarrow mathrm{e^+ e^-}$, $mu^+mu^-$ searches due to the small branching ratios in the $rho-omega$ resonance region. We found no evidence for a signal and set a limit at 90% CL on the mixing strength between the photon and the dark photon, $varepsilon^2$, in the U mass range between $527$ and $987$~MeV. Above 700 MeV this new limit is more stringent than previous ones.
We searched for the $mu^+mu^-$ decay of a light vector gauge boson, also known as dark photon, in the $e^+ e^- to mu^+ mu^- gamma_{rm ISR}$ process by means of the Initial State Radiation (ISR) method. We used 1.93~fb$^{-1}$ of data collected by the
KLOE experiment at the DA$Phi$NE $phi$-factory. No structures have been observed over the irreducible $mu^+ mu^-$ background. A 90% CL limit on the ratio $varepsilon^2=alpha^{prime}/alpha$ between the dark coupling constant and the fine structure constant of $ 3times 10^{-6}-2times 10^{-7}$ has been set in the dark photon mass region between 519 MeV and 973 MeV. This new limit has been combined with the published result obtained investigating the hypothesis of the dark photon decaying into hadrons in $e^+ e^- to pi^+ pi^- gamma_{rm ISR}$ events. The combined 90% CL limit increases the sensitivity especially in the $rho-omega$ interference region and excludes $varepsilon^2$ greater than $(13-2)times 10^{-7}$. For dark photon masses greater than 600 MeV the combined limit is lower than 8~$times, 10^{-7}$ resulting more stringent than present constraints from other experiments.
We describe the status of the analyses in progress on light meson spectroscopy in the KLOE experiment. We present the analyses of phi decays into f0(980)gamma and a0(980)gamma, the Dalitz plot analysis of the eta to pie+ pie- pie0 decay, the branchin
g ratio measurement of eta to pie0 gamma gamma, the upper limits on Br(eta to 3 gamma) and Br(eta to pie^+ pie^-), the measurement of the ratio Br(phi to eta gamma)/Br(phi to eta gamma) and phi leptonic width measurements.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
