Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userA Combination of CDF and DO Limits on the Branching Ratio of B_s(d) to mu+ mu- Decays
74
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We combine the results of CDF and DO searches for the rare decays B_s to mu+ mu- and B_d to mu+ mu-. The experiments use 364 pb-1 and 300 pb-1 of data respectively. The limits on the branching ratios are obtained by normalizing the estimated sensitivity to the decay B+ to J/psi K+, taking into account the fragmentation ratios f_u/f_s(d). The combined results exclude branching ratios of BR(B_s to mu+ mu-) > 1.5x10-7 and BR(B_d to mu+ mu- > 4.0x10-8 at 95% confidence level. These are the most stringent limits on these decays at the present time.
rate research
Read More
We study the prospects of measurement of the branching ratio of $h to mu ^+ mu ^-$ at the International Linear Collider (ILC). The study is performed at center-of-mass energies of 250 GeV and 500 GeV, using fully-simulated MC samples with the International Large Detector (ILD) model. For both center-of-mass energies, the two final states $qoverline{q}h$ and $ u overline{ u}h$ have been analyzed. For an integrated luminosity of 2000 fb$^{-1}$ at 250 GeV and 4000 fb$^{-1}$ at 500 GeV, corresponding to the H20 running scenario as well as its staged version, the precision on $sigma times mathrm{BR}(h to mu ^+ mu ^-)$ is estimated.
The pure leptonic decay B_s -> mu mu is strongly suppressed in the Standard Model (SM), but can have large enhancements in Supersymmetry, especially at large values of tanbe. New limits on this decay channel from recent LHC data have been used to claim that these limits restrict the SUSY parameter space even more than the direct searches. However, direct searches are hardly dependent on tanbe, while BR(B_s -> mu mu) is proportional to tanbe^6. The relic density constraint requires large tanbe in a large region of the parameter space, which can lead to large values of B_s -> mu mu. Nevertheless, the experimental upper limit on BR(B_s -> mu mu) is not constraining the parameter space of the CMSSM more than the direct searches and the present Higgs limits, if combined with the relic density. We also observe SUSY parameter regions with negative interferences, where the B_s -> mu mu value is up to a factor three below the SM expectation, even at large values of tanbe.
A search for non-resonant D+(s) to pi+mu+mu- and D+(s) to pi-mu+mu+ decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 1.0 fb-1, at sqrt(s) = 7 TeV recorded by the LHCb experiment in 2011. No signals are observed and the 90% (95%) confidence level (CL) limits on the branching fractions are B(D+ to pi+mu+mu-) < 7.3 (8.3) x 10-8, B(Ds+ to pi+mu+mu-) < 4.1 (4.8) x 10-7, B(D+ to pi-mu+mu+) < 2.2 (2.5) x 10-8, B(Ds+ to pi-mu+mu+) < 1.2 (1.4) x 10-7. These limits are the most stringent to date.
The ratio of branching fractions ${cal{R}}(D^{*-})equiv {cal{B}}(B^0 to D^{*-} tau^+ u_{tau})/{cal{B}}(B^0 to D^{*-} mu^+ u_{mu})$ is measured using a data sample of proton-proton collisions collected with the LHCb detector at center-of-mass energies of 7 and 8 Tev, corresponding to an integrated luminosity of 3$~$fb$^{-1}$. For the first time ${cal{R}}(D^{*-})$ is determined using the $tau$ lepton decays with three charged pions in the final state. The $B^0 to D^{*-} tau^+ u_{tau}$ yield is normalized to that of the $B^0to D^{*-} pi^+pi^-pi^+$ mode, providing a measurement of ${cal{B}}(B^0to D^{*-}tau^+ u_{tau})/{cal{B}}(B^0to D^{*-}pi^+pi^-pi^+) = 1.97 pm 0.13 pm 0.18$, where the first uncertainty is statistical and the second systematic. The value of ${cal{B}}(B^0 to D^{*-} tau^+ u_{tau}) = (1.42 pm 0.094 pm 0.129 pm 0.054)% $ is obtained, where the third uncertainty is due to the limited knowledge of the branching fraction of the normalization mode. Using the well-measured branching fraction of the $B^0 to D^{*-} mu^+ u_{mu}$ decay, a value of ${cal{R}}(D^{*-}) = 0.291 pm 0.019 pm 0.026 pm 0.013$ is established, where the third uncertainty is due to the limited knowledge of the branching fractions of the normalization and $B^0to D^{*-}mu^+ u_{mu}$ modes. This measurement is in agreement with the Standard Model prediction and with previous results.
We report on a measurement of the decay $K_Lrightarrowmu^+mu^-gamma$ from Fermilab experiment E799. We observe $207$ candidate signal events with an estimated background of $10.5 pm 4.0$ events and establish $B(K_Lrightarrowmu^+mu^-gamma) = (3.23pm 0.23(stat) pm 0.19(sys))times 10^{-7}$. This provides the first measurement of the $Kgammagamma^*$ form factor in the muonic Dalitz decay mode of the $K_L$.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
