Search results for " hadrons"
showing 10 items of 417 documents
"Table 3" of "Energy dependence of event shapes and of alpha(s) at LEP-2."
1999
Moments of the Thrust Minor distributions at cm energies 133, 161, 172 and 183 GeV.
"Table 28" of "Energy dependence of event shapes and of alpha(s) at LEP-2."
1999
Distribution of the Heavy Jet Masses (MH**2/EVIS**2) at cm energy 183 GeV.
"Table 30" of "Energy dependence of event shapes and of alpha(s) at LEP-2."
1999
Distribution of the Light Jet Masses (ML**2/EVIS**2) at cm energy 183 GeV.
Direct X(3872) production in e+e- collisions
2014
Direct production of the charmonium-like state $X(3872)$ in $e^+e^-$ collisions is considered in the framework of the vector meson dominance model. An order-of-magnitude estimate for the width $\Gamma(X\to e^+e^-)$ is found to be $\gtrsim$0.03 eV. The same approach applied to the $\chi_{c1}$ charmonium decay predicts the corresponding width of the order 0.1 eV in agreement with earlier estimates. Experimental perspectives for the direct production of the $1^{++}$ charmonia in $e^+e^-$ collisions are briefly discussed.
Precision Measurement of the Mass and Lifetime of the Ξ[0 over b] Baryon
2014
Using a proton-proton collision data sample corresponding to an integrated luminosity of 3 fb$^{-1}$ collected by LHCb at center-of-mass energies of 7 and 8 TeV, about 3800 $\Xi_b^0\to\Xi_c^+\pi^-$, $\Xi_c^+\to pK^-\pi^+$ signal decays are reconstructed. From this sample, the first measurement of the $\Xi_b^0$ baryon lifetime is made, relative to that of the $\Lambda_b^0$ baryon. The mass differences $M(\Xi_b^0)-M(\Lambda_b^0)$ and $M(\Xi_c^+)-M(\Lambda_c^+)$ are also measured with precision more than four times better than the current world averages. The resulting values are $\frac{\tau_{\Xi_b^0}}{\tau_{\Lambda_b^0}} = 1.006\pm0.018\pm0.010$, $M(\Xi_b^0) - M(\Lambda_b^0) = 172.44\pm0.39\pm…
Spectroscopy, lifetime and decay modes of the $T^-_{bb}$ tetraquark
2019
We present the first full-fledged study of the flavor-exotic isoscalar $T_{bb}^-\equiv b b \bar u \bar d$ tetraquark with spin and parity $J^P=1^+$. We report accurate solutions of the four-body problem in a quark model, characterizing the structure of the state as a function of the ratio $M_Q/m_q$ of the heavy to light quark masses. For such a standard constituent model, $T_{bb}^-$ lies approximately 150 MeV below the strong decay threshold $B^-\bar {B^*}^{0}$ and 105 MeV below the electromagnetic decay threshold $B^- \bar B^0 \gamma$. We evaluate the lifetime of $T_{bb}^-$, identifying the promising decay modes where the tetraquark might be looked for in future experiments. Its total deca…
Measurement of the spin density matrix for the rho(0), K*(0)(892) and phi produced in Z(0) decays
1997
The spin density matrix elements for the rho(0), K-*0(892) and phi produced in hadronic Z(0) decays are measured in the DELPHI detector. There is no evidence for spin alignment of the K-*0(892) and phi, in the region x(p) less than or equal to 0.3 (x(p) = p/p(beam)), where rho(00) = 0.33 +/- 0.05 and rho(00) = 0.30 +/- 0.04, respectively. In the fragmentation region, x(p) greater than or equal to 0.4, there is some indication for spin alignment of the rho(0) and K-*0(892), since rho(00) = 0.43 +/- 0.05 and rho(00) = 0.46 +/- 0.08, respectively. These values are compared with those found in meson-induced hadronic reactions. For the phi, rho(00) = 0.30 +/- 0.04 for x(p) greater than or equal …
Updated precision measurement of the average lifetime of B hadrons
1996
The measurement of the average lifetime of B hadrons using inclusively reconstructed secondary vertices has been updated using both an improved processing of previous data and additional statistics from new data. This has reduced the statistical and systematic uncertainties and gives \tau_{\mathrm{B}} = 1.582 \pm 0.011\ \mathrm{(stat.)} \pm 0.027\ \mathrm{(syst.)}\ \mathrm{ps.} Combining this result with the previous result based on charged particle impact parameter distributions yields \tau_{\mathrm{B}} = 1.575 \pm 0.010\ \mathrm{(stat.)} \pm 0.026\ \mathrm{(syst.)}\ \mathrm{ps.}
Charm and hidden charm scalar mesons in the nuclear medium
2009
We study the renormalization of the properties of low-lying charm and hidden charm scalar mesons in a nuclear medium, concretely of the D-s0(2317) and the theoretical hidden charm state X(3700). We find that for the D-s0(2317), with negligible width at zero density, the width becomes about 100 MeV at normal nuclear-matter density, while in the case of the X(3700) the width becomes as large as 200 MeV. We discuss the origin of this new width and trace it to reactions occurring in the nucleus, while offering a guideline for future experiments testing these changes. We also show how those medium modifications will bring valuable information on the nature of the scalar resonances and the mechan…
Pion-photon transition distribution amplitudes in the Nambu-Jona-Lasinio model
2007
12 pages, 6 figures.-- PACS nrs.: 13.60.-r; 11.10.St; 12.38.Lg; 24.10.Jv.-- ISI Article Identifier: 000251327200049.-- ArXiv pre-print available at: http://arxiv.org/abs/0707.3366