A
bstract
The time-dependent
CP
asymmetry in
B
0
→
K
res
γ → π
+
π
−
K
S
γ is sensitive to the photon polarisation in the quark level process
b
→
s
γ. While this polarisation is predominantly ...left-handed in the standard model, it could be modified by the existence of new physics contributions that may possess different
CP
properties. In this paper, we derive the
CP
violation formulae for
B
0
→
K
res
γ → π
+
π
−
K
S
γ including the most dominant intermediate states. We propose a new observable that could be measured in a time-dependent amplitude analysis of
B
0
→ π
+
π
−
K
S
γ decays, providing a stringent contraint on the photon polarisation. We discuss the future prospects for obtaining such constraints from measurements at Belle II and LHCb.
The time-dependent CP asymmetry in B0 → Kresγ → π+π−KSγ is sensitive to the photon polarisation in the quark level process b → sγ. While this polarisation is predominantly left-handed in the standard ...model, it could be modified by the existence of new physics contributions that may possess different CP properties. In this paper, we derive the CP violation formulae for B0 → Kresγ → π+π−KSγ including the most dominant intermediate states. We propose a new observable that could be measured in a time-dependent amplitude analysis of B0 → π+π−KSγ decays, providing a stringent contraint on the photon polarisation. We discuss the future prospects for obtaining such constraints from measurements at Belle II and LHCb.
Using recent measurements of the b-quark fragmentation distribution obtained in e+e−→bb̄ events, registered at the Z pole, the non-perturbative QCD component of the distribution has been extracted ...independently of any hadronic physics modelling. This distribution depends only on the way the perturbative QCD component has been denned. When the perturbative QCD component is taken from a parton shower Monte Carlo, the non-perturbative QCD component is rather similar with those obtained from the Lund or Bowler models. When the perturbative QCD component is the result of an analytic NLL computation, the non-perturbative QCD component has to be extended in a non-physical region and thus cannot be described by any hadronic modelling. In the two examples, used to characterize these two situations, which are studied at present, it happens that the extracted non-perturbative QCD distribution has the same shape, being simply translated to higher-x values in the second approach, illustrating the ability of the analytic perturbative QCD approach to account for softer gluon radiation than with a parton shower generator.
Abstract Production of ... mesons in proton-lead collisions at a nucleon-nucleon centre-of-mass energy ... = 5 TeV is studied with the LHCb detector. The analysis is based on a data sample ...corresponding to an integrated luminosity of 1.6 nb-1. The ... mesons of transverse momenta up to 15 GeV/c are reconstructed in the dimuon decay mode. The rapidity coverage in the centre-of-mass system is 1.5 < y < 4.0 (forward region) and -5.0 < y < -2.5 (backward region). The forward-backward production ratio and the nuclear modification factor for ...(1S) mesons are determined. The data are compatible with the predictions for a suppression of ...(1S) production with respect to proton-proton collisions in the forward region, and an enhancement in the backward region. The suppression is found to be smaller than in the case of prompt J/psi mesons. Figure not available: see fulltext.
This paper focuses on mechanical aspects of chromatin biological functioning. Within a basic geometric modeling of the chromatin assembly, we give a complete set of elastic constants (twist and bend ...persistence lengths, stretch modulus and twist-stretch coupling constant) of the so-called 30-nm chromatin fiber, in terms of DNA elastic properties and geometric properties of the fiber assembly. The computation naturally embeds the fiber within a current analytical model known as the "extensible wormlike rope," allowing a straightforward prediction of the force-extension curves. We show that these elastic constants are strongly sensitive to the linker length, up to 1 bp, or equivalently to its twist, and might locally reach very low values, yielding a highly flexible and extensible domain in the fiber. In particular, the twist-stretch coupling constant, reflecting the chirality of the chromatin fiber, exhibits steep variations, and sign changes when the linker length is varied. We argue that this tunable elasticity might be a key feature for chromatin function, for instance, in the initiation and regulation of transcription.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) The energy flow created in pp collisions at ... is studied within the pseudorapidity range 1.9<eta<4.9 with data collected ...by the LHCb experiment. The measurements are performed for inclusive minimum-bias interactions, hard scattering processes and events with an enhanced or suppressed diffractive contribution. The results are compared to predictions given by Pythia-based and cosmic-ray event generators, which provide different models of soft hadronic interactions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract A combination of measurements sensitive to the CKM angle γ from LHCb is performed. The inputs are from analyses of time-integrated B + arrow right DK +, B 0 arrow right DK 0, B 0 arrow right ...DK +pi- and B + arrow right DK +pi+pi- tree-level decays. In addition, results from a time-dependent analysis of B s 0 arrow rightD s K ± decays are included. The combination yields γ=(72.2 -7.3 +6.8 )°, where the uncertainty includes systematic effects. The 95.5% confidence level interval is determined to be γ 55.9, 85.2°. A second combination is investigated, also including measurements from B + arrow right Dpi+ and B + arrow right Dpi+pi-pi+ decays, which yields compatible results. Figure not available: see fulltext.
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, CP violation parameters, parameters of semileptonic decays, and Cabibbo–Kobayashi–Maskawa matrix elements.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Abstract A measurement of the inclusive Z arrow right ττ cross-section in pp collisions at ... is presented based on a ...dataset of 1.0 fb^sup -1^ collected by the LHCb detector. Candidates for Z arrow right tau tau decays are identified through reconstructed final states with two muons, a muon and an electron, a muon and a hadron, or an electron and a hadron. The production cross-section for Z bosons, with invariant mass between 60 and 120 GeV/c ^sup 2^, which decay to tau leptons with transverse momenta greater than 20 GeV/c and pseudorapidities between 2.0 and 4.5, is measured to be sigma^sub pparrow rightZarrow rightττ^ = 71.4 ± 3.5 ± 2.8 ± 2.5 pb; the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the integrated luminosity. The ratio of the cross-sections for Z arrow right tau tau to Z arrow right mumu is determined to be 0.93 ± 0.09, where the uncertainty is the combination of statistical, systematic, and luminosity uncertainties of the two measurements.Figure not available: see fulltext.
We measure the total branching fraction of the flavor-changing neutral-current process B → X s ℓ + ℓ − , along with partial branching fractions in bins of dilepton and hadronic system ( X s ) mass, ...using a sample of 471 × 1 0 6 Υ ( 4 S ) → B ¯ B events recorded with the BABAR detector. The admixture of charged and neutral B mesons produced at PEP-II2 are reconstructed by combining a dilepton pair with 10 different X s final states. Extrapolating from a sum over these exclusive modes, we measure a lepton-flavor-averaged inclusive branching fraction B ( B → X s ℓ + ℓ − ) = 6.7 3 + 0.70 − 0.64 ( stat ) + 0.34 − 0.25 ( exp syst ) ± 0.50 ( model syst ) × 1 0 − 6 for m 2 ℓ + ℓ − > 0.1 GeV 2 / c 4 . Restricting our analysis exclusively to final states from which a decaying B meson's flavor can be inferred, we additionally report measurements of the direct C P asymmetry A C P in bins of dilepton mass; over the full dilepton mass range, we find A C P = 0.04 ± 0.11 ± 0.01 for a lepton-flavor-averaged sample.
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