This article reports world averages of measurements of
b
-hadron,
c
-hadron, and
τ
-lepton properties obtained by the Heavy Flavor Averaging Group using results available through summer 2016. For the ...averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters,
C
P
violation parameters, parameters of semileptonic decays, and Cabbibo–Kobayashi–Maskawa matrix elements.
Abstract This article reports world averages of measurements of b-hadron, c-hadron, and $$\tau $$ τ -lepton properties obtained by the Heavy Flavor Averaging Group using results available through ...summer 2016. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, $$C\!P$$ C P violation parameters, parameters of semileptonic decays, and Cabbibo–Kobayashi–Maskawa matrix elements.
This paper reports world averages of measurements of
b
-hadron,
c
-hadron, and
τ
-lepton properties obtained by the Heavy Flavour Averaging Group using results available through September 2018. In ...rare cases, significant results obtained several months later are also used. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters,
C
P
violation parameters, parameters of semileptonic decays, and Cabibbo–Kobayashi–Maskawa matrix elements.
Abstract
We present a measurement of the Michel parameters of the $\tau$ lepton, $\bar{\eta}$ and $\xi\kappa$, in the radiative leptonic decay $\tau^- \rightarrow \ell^- \nu_{\tau} \bar{\nu}_{\ell} ...\gamma$ using 711 f$\mathrm{b}^{-1}$ of collision data collected with the Belle detector at the KEKB $e^+e^-$ collider. The Michel parameters are measured in an unbinned maximum likelihood fit to the kinematic distribution of $e^+e^-\rightarrow\tau^+\tau^-\rightarrow (\pi^+\pi^0 \bar{\nu}_\tau)(\ell^-\nu_{\tau}\bar{\nu}_{\ell}\gamma)$$(\ell=e$ or $\mu)$. The measured values of the Michel parameters are $\bar{\eta} = -1.3 \pm 1.5 \pm 0.8$ and $\xi\kappa = 0.5 \pm 0.4 \pm 0.2$, where the first error is statistical and the second is systematic. This is the first measurement of these parameters. These results are consistent with the Standard Model predictions within their uncertainties, and constrain the coupling constants of the generalized weak interaction.
Display omitted
First evidence of a structure in the J/ψΛ invariant mass distribution is obtained from an amplitude analysis of Ξb-→J/ψΛK- decays. The observed structure is consistent with being due ...to a charmonium pentaquark with strangeness with a significance of 3.1σ including systematic uncertainties and look-elsewhere effect. Its mass and width are determined to be 4458.8±2.9-1.1+4.7MeV and 17.3±6.5-5.7+8.0MeV, respectively, where the quoted uncertainties are statistical and systematic. The structure is also consistent with being due to two resonances. In addition, the narrow excited Ξ- states, Ξ1690- and Ξ1820-, are seen for the first time in a Ξb- decay, and their masses and widths are measured with improved precision. The analysis is performed using pp collision data corresponding to a total integrated luminosity of 9 fb-1, collected with the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV.
The Belle II Physics Book Kou, E; Bishara, F; Brod, J ...
Progress of theoretical and experimental physics,
12/2019, Letnik:
2019, Številka:
12
Journal Article
Recenzirano
Odprti dostop
We present the physics program of the Belle II experiment, located on the intensity frontier SuperKEKB e+e- collider. Belle II collected its first collisions in 2018, and is expected to operate for ...the next decade. It is anticipated to collect 50/ab of collision data over its lifetime. This book is the outcome of a joint effort of Belle II collaborators and theorists through the Belle II theory interface platform (B2TiP), an effort that commenced in 2014. The aim of B2TiP was to elucidate the potential impacts of the Belle II program, which includes a wide scope of physics topics: B physics, charm, tau, quarkonium, electroweak precision measurements and dark sector searches. It is composed of nine working groups (WGs), which are coordinated by teams of theorist and experimentalists conveners: Semileptonic and leptonic B decays, Radiative and Electroweak penguins, φ1 and φ2 (time-dependent CP violation) measurements, φ3 measurements, Charmless hadronic B decay, Charm, Quarkonium(like), tau and low-multiplicity processes, new physics and global fit analyses. This book highlights "golden- and silver-channels", i.e. those that would have the highest potential impact in the field. Theorists scrutinised the role of those measurements and estimated the respective theoretical uncertainties, achievable now as well as prospects for the future. Experimentalists investigated the expected improvements with the large dataset expected from Belle II, taking into account improved performance from the upgraded detector.
Angular analysis of the rare decay Bs0→ ϕμ+μ Ackernley, T.; Balagura, V.; Belyaev, I. ...
The journal of high energy physics,
11/2021, Letnik:
2021, Številka:
11
Journal Article
Recenzirano
Odprti dostop
A
bstract
An angular analysis of the rare decay
B
s
0
→ ϕμ
+
μ
−
is presented, using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, ...corresponding to an integrated luminosity of 8.4 fb
−
1
. The observables describing the angular distributions of the decay
B
s
0
→ ϕμ
+
μ
−
are determined in regions of
q
2
, the square of the dimuon invariant mass. The results are consistent with Standard Model predictions.
Quantum chromodynamics, the theory of the strong force, describes interactions of coloured quarks and gluons and the formation of hadronic matter. Conventional hadronic matter consists of baryons and ...mesons made of three quarks and quark-antiquark pairs, respectively. Particles with an alternative quark content are known as exotic states. Here a study is reported of an exotic narrow state in the (DD0)-D-0 pi(+) mass spectrum just below the D*+D-0 mass threshold produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The state is consistent with the ground isoscalar T-cc(+), tetraquark with a quark content of cc (u) over bar(d) over bar and spin-parity quantum numbers J(P) =1(+). Study of the DD mass spectra disfavours interpretation of the resonance as the isovector state. The decay structure via intermediate off-shell D*(+) mesons is consistent with the observed D-0 pi(+) mass distribution. To analyse the mass of the resonance and its coupling to the DID system, a dedicated model is developed under the assumption of an isoscalar axial-vector T-cc(+), state decaying to the D*D channel. Using this model, resonance parameters including the pole position, scattering length, effective range and compositeness are determined to reveal important information about the nature of the T-cc(+), state. In addition, an unexpected dependence of the production rate on track multiplicity is observed.
A
bstract
The
ϒ
(1
S
)
μ
+
μ
−
invariant-mass distribution is investigated for a possible exotic meson state composed of two
b
quarks and two
b
¯
quarks,
X
b
b
¯
b
b
¯
. The analysis is based on a ...data sample of
pp
collisions recorded with the LHCb detector at centre-of-mass energies
s
=
7
, 8 and 13 TeV, corresponding to an integrated luminosity of 6.3 fb
−1
. No significant excess is found, and upper limits are set on the product of the production cross-section and the branching fraction as functions of the mass of the
X
b
b
¯
b
b
¯
state. The limits are set in the fiducial volume where all muons have pseudorapidity in the range 2
.
0
,
5
.
0, and the
X
b
b
¯
b
b
¯
state has rapidity in the range 2
.
0
,
4
.
5 and transverse momentum less than 15 GeV/
c
.
PDF
