Search results for "Invariant Mass"
showing 10 items of 280 documents
The radiative decay of the Lambda(1405) and its two-pole structure
2007
We evaluate theoretically the radiative decay widths into $\gamma\Lambda$ and $\gamma\Sigma^0$ of the two poles of the $\Lambda(1405)$ found in chiral unitary theories and we find quite different results for each of the two poles. We show that, depending on which reaction is used to measure the $\Lambda(1405)$ radiative decays, one gives more weight to one or the other pole, resulting in quite different shapes in the $\gamma\Lambda(\Sigma^0)$ invariant mass distributions. Our results for the high-energy pole agree with those of the empirical determination of the $\gamma\Lambda$ and $\gamma\Sigma^0$ radiative widths (based on an isobar model fitting of the $K^-p$ atom data), which are someti…
An upper limit for the τ neutrino mass from τ → 5π(π0)ντ decays
1995
An upper limit for the tau-neutrino mass has been determined from the decay tau -> 5pi+- \nu_tau using data collected with the OPAL detector from 1991 to 1995 in e+e- collisions at \sqrt{s} ~ M_Z. A limit of 43.2 MeV at 95% CL is obtained using a two-dimensional method in the 5pi invariant mass and energy distribution from 22 selected events. Combining this result with OPAL's previously published measurement using tau+tau- -> 3h+- \bar{nu}_tau 3h-+ \nu_tau decays, a new combined limit of m_{nu_tau} < 27.6 MeV (95% CL) is obtained.
Observation of a Charged(DD¯*)±Mass Peak ine+e−→πDD¯*ats=4.26 GeV
2014
We report on a study of the process e(+)e(-) -> pi(+/-) (D (D) over bar*)(-/+) at root s = 4.26 GeV using a 525 pb(-1) data sample collected with the BESIII detector at the BEPCII storage ring. A distinct charged structure is observed in the (D (D) over bar*)(-/+) invariant mass distribution. When fitted to a mass- dependent- width Breit- Wigner line shape, the pole mass and width are determined to be M-pole (3883: 9 +/- 1.5 (stat) +/- 4.2 dsyst__ MeV= c(2) and Gamma(pole) = (24: 8 +/- 3.3 (stat) +/- 11: 0 (syst)) MeV. The mass and width of the structure, which we refer to as Z(c)(3885), are 2 sigma and 1 sigma, respectively, below those of the Z(c)(3900) -> pi(+/-) J/psi peak observed by B…
Improved limit on the electron-antineutrino rest mass from tritium ß-decay
1993
Abstract The endpoint region of the β-spectrum of tritium was remeasured by an electrostatic spectrometer with magnetic guiding field. It enabled the search for a rest mass of the electron-antineutrino with improved precision. The result is m2v=−39±34stat±15syst(eV/c2)2, from which an upper limit of mv m( T )−m( 3 He )=18 591±3 eV /c 2 .
Dalitz plot analyses ofB0→D−D0K+andB+→D¯0D0K+decays
2015
We present Dalitz plot analyses for the decays of B mesons to D^−D^0K^+ and D^0D^0K^+. We report the observation of the D^∗_(s1)(2700)^+ resonance in these two channels and obtain measurements of the mass M(D^∗_(s1)(2700)+)=2699^(+14)_(−7) MeV/c^2 and of the width Γ(D^∗_(s1)(2700)+)=127^(+24)_(−19) MeV, including statistical and systematic uncertainties. In addition, we observe an enhancement in the D^0K^+ invariant mass around 2350–2500 MeV/c^2 in both decays B^0→D^−D^0K^+ and B^+→D^0D^0K^+, which we are not able to interpret. The results are based on 429 fb^(−1) of data containing 471×10^6BB pairs collected at the Υ(4S) resonance with the BABAR detector at the SLAC National Accelerato…
Study of the rare Bs0 and B0 decays into the π+π−μ+μ− final state
2015
A search for the rare decays B0s→π+π−μ+μ− and B0→π+π−μ+μ− is performed in a data set corresponding to an integrated luminosity of 3.0 fb−1 collected by the LHCb detector in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV. Decay candidates with pion pairs that have invariant mass in the range 0.5-1.3 GeV/c2 and with muon pairs that do not originate from a resonance are considered. The first observation of the decay B0s→π+π−μ+μ− and the first evidence of the decay B0→π+π−μ+μ− are obtained and the branching fractions are measured to be B(B0s→π+π−μ+μ−)=(8.6±1.5(stat)±0.7(syst)±0.7(norm))×10−8 and B(B0→π+π−μ+μ−)=(2.11±0.51(stat)±0.15(syst)±0.16(norm))×10−8, where the third unc…
A new upper limit of the electron anti neutrino rest mass from tritium β-decay
1993
Abstract A new upper limit of the electron anti neutrino rest mass has been deduced from the tritium β-decay spectrum. A source of molecular tritium has been investigated with a new solenoid retarding spectrometer. The results are m ν ϵ 2 = −38.8 ± 34.1 stat ± 15.1 syst (eV) 2 /c 4 from which we conclude m ν ϵ ≤ 7.2 eV/c 2 with 95% c.l. Our β-endpoint corresponds to a 3H-3He atomic mass difference of Δm( 3 H- 3 He) = 18590.8 ± 3 eV/c 2 (1σ) .
Hypernuclear spectroscopy of products from Li-6 projectiles on a carbon target at 2 A GeV
2013
WOS: 000322848900009
"Table 1" of "Search for pairs of highly collimated photon-jets in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector"
2018
Distribution of the reconstructed diphoton mass for data events passing the analysis selection, in the low-$\Delta E$ category. There are no data events above 2700 GeV.
"Table 2" of "Search for pairs of highly collimated photon-jets in $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector"
2018
Distribution of the reconstructed diphoton mass for data events passing the analysis selection, in the high-$\Delta E$ category. There are no data events above 2700 GeV.