Search results for "Charm"
showing 10 items of 390 documents
"Table 5" of "Study of D*+ production in nu/mu charged current interactions in the NOMAD experiment."
2002
Total yield of charged D* mesons per CC events.
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…
Dielectron production in proton-proton and proton-lead collisions at √sNN=5.02TeV
2020
The first measurements of dielectron production at midrapidity (|ηe| < 0.8) in proton–proton and proton–lead collisions at √sNN = 5.02 TeV at the LHC are presented. The dielectron cross section is measured with the ALICE detector as a function of the invariant mass mee and the pair transverse momentum pT, ee in the ranges mee < 3.5 GeV/c2 and pT, ee < 8 GeV/c, in both collision systems. In proton–proton collisions, the charm and beauty cross sections are determined at midrapidity from a fit to the data with two different event generators. This complements the existing dielectron measurements performed at √s = 7 and 13 TeV. The slope of the √s dependence of the three measurements is…
Amplitude analysis and branching-fraction measurement of D-s(+) -> K-S(0)pi(+)pi(0)
2022
Journal of high energy physics 2021(6), 181 (2021). doi:10.1007/JHEP06(2021)181
Measurement of the spin of the Xi(1530) resonance
2008
The properties of the Xi(1530) resonance are investigated in the Lambdac+ --> Xi- pi+ K+ decay process. The data sample was collected with the BaBar detector at the SLAC PEP-II asymmetric-energy e+ e- collider operating at center of mass energies 10.58 and 10.54 GeV. The corresponding integrated luminosity is approximately 230 inverse fb. The spin of the Xi(1530) is established to be 3/2. The existence of an S-wave amplitude in the Xi- pi+ system is inferred, and its interference with the Xi(1530)0 amplitude provides the first clear demonstration of the Breit-Wigner phase motion expected for the Xi(1530). The P_1(cos[theta(Xi-)]) Legendre polynomial moment indicates the presence of a sig…
Lateral distribution of muons in IceCube cosmic ray events
2013
In cosmic ray air showers, the muon lateral separation from the center of the shower is a measure of the transverse momentum that the muon parent acquired in the cosmic ray interaction. IceCube has observed cosmic ray interactions that produce muons laterally separated by up to 400 m from the shower core, a factor of 6 larger distance than previous measurements. These muons originate in high pT (>2 GeV/c) interactions from the incident cosmic ray, or high-energy secondary interactions. The separation distribution shows a transition to a power law at large values, indicating the presence of a hard pT component that can be described by perturbative quantum chromodynamics. However, the ra…
Odd parity bottom-flavored baryon resonances
2013
The LHCb Collaboration has recently observed two narrow baryon resonances with beauty. Their masses and decay modes look consistent with the quark model orbitally excited states Lambda(b)(5912) and Lambda(b)*(5920), with quantum numbers J(P) = 1/2(-) and 3/2(-), respectively. We predict the existence of these states within a unitarized meson-baryon coupled-channel dynamical model, which implements heavy-quark spin symmetry. Masses, quantum numbers and couplings of these resonances to the different meson-baryon channels are obtained. We find that the resonances Lambda(0)(b)(5912) and Lambda(0)(b)(5920) are heavy-quark spin symmetry partners, which naturally explains their approximate mass de…
A strategy to study the role of the charm quark in explaining the Delta{I}=1/2 rule
2004
We present a strategy designed to separate several possible origins of the well-known enhancement of the Delta{I}=1/2 amplitude in non-leptonic kaon decays. In particular, we seek to disentangle the contribution of physics at the typical QCD scale (soft-gluon exchange) from the effects at the scale of the charm quark mass. This is achieved by considering QCD with an unphysically light charm quark, so that the theory possesses an approximate SU(4)_L x SU(4)_R chiral symmetry. By computing the relevant operator matrix elements and monitoring their values as the charm quark mass departs from the SU(4)-symmetric situation, the role of the charm quark can be assessed. We study the influence of t…
Measurement of the partial width of the decay of the Z0 into charm quark pairs
1990
A determination of the partial width Γc̄ of the Z0 boson into charm quark pairs is presented, based on a total sample of 36 900 Z0 hadronic decays measured with the DELPHI detector at the LEP collider. The production rate of cc events is derived from the inclusive analysis of charged pions coming from the decay of charmed meson D*+-→D0π+ and D*-→D̄0π- where the π± is constrained by kinematics to have a low pT with respect to the jet axis. The probability to procedure these π± from D*± decay in cc events is taken to be 0.31±0.05 as measured at √S = 10.55 GeV. The measured relative partial width Γ∞/Γh = 0.162± 0.030(stat.) ± 0.050(syst.) is in good agreement with the standard model value of 0…