Challenges in semileptonic B decays Gambino, P.; Kronfeld, A. S.; Rotondo, M. ...
The European physical journal. C, Particles and fields,
10/2020, Volume:
80, Issue:
10
Journal Article
Peer reviewed
Open access
Two of the elements of the Cabibbo–Kobayashi–Maskawa quark mixing matrix,
|
V
ub
|
and
|
V
cb
|
, are extracted from semileptonic
B
decays. The results of the
B
factories, analysed in the light of ...the most recent theoretical calculations, remain puzzling, because for both
|
V
ub
|
and
|
V
cb
|
the exclusive and inclusive determinations are in clear tension. Further, measurements in the
τ
channels at Belle, Babar, and LHCb show discrepancies with the Standard Model predictions, pointing to a possible violation of lepton flavor universality. LHCb and Belle II have the potential to resolve these issues in the next few years. This article summarizes the discussions and results obtained at the MITP workshop held on April 9–13, 2018, in Mainz, Germany, with the goal to develop a medium-term strategy of analyses and calculations aimed at solving the puzzles. Lattice and continuum theorists working together with experimentalists have discussed how to reshape the semileptonic analyses in view of the much higher luminosity expected at Belle II, searching for ways to systematically validate the theoretical predictions in both exclusive and inclusive
B
decays, and to exploit the rich possibilities at LHCb.
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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.
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A
bstract
Production cross-sections of prompt charm mesons are measured with the first data from
pp
collisions at the LHC at a centre-of-mass energy of 13 TeV. The data sample corresponds to an ...integrated luminosity of 4.98 ± 0.19 pb
−1
collected by the LHCb experiment. The production cross-sections of
D
0
,
D
+
,
D
s
+
, and
D
*+
mesons are measured in bins of charm meson transverse momentum,
p
T
, and rapidity,
y
, and cover the range 0 <
p
T
< 15GeV/c and 2.0 <
y
< 4.5. The inclusive cross-sections for the four mesons, including charge conjugation, within the range of 1 <
p
T
< 8 GeV/c are found to be
σ
pp
→
D
0
X
=
2460
±
3
±
130
μ
b
σ
pp
→
D
+
X
=
1000
±
3
±
110
μ
b
σ
pp
→
D
s
+
X
=
460
±
13
±
100
μ
b
σ
pp
→
D
∗
+
X
=
880
±
5
±
140
μ
b
where the uncertainties are due to statistical and systematic uncertainties, respectively.
LHCb is planning major changes for its data processing and analysis workflows for LHC Run 3. Removing the hardware trigger, a software only trigger at 30 MHz will reconstruct events using final ...alignment and calibration information provided during the triggering phase. These changes pose a major strain on the online software framework which needs to improve significantly. The foreseen changes in the area of the core framework include a re-design of the event scheduling, introduction of concurrent processing, optimizations in processor cache accesses and code vectorization. Furthermore changes in the areas of event model, conditions data and detector description are foreseen. The changes in the data processing workflow will allow an unprecedented amount of signal events to be selected and therefore increase the load on the experiments simulation needs. Several areas of improvement for fast simulation are currently being investigated together with improvements needed in the area of distributed computing. Finally the amount of data stored needs to be reflected in the analysis computing model where individual user analysis on distributed computing resources will become inefficient. This contribution will give an overview of the status of those activities and future plans in the different areas from the perspective of the LHCb computing project.
The LHCb detector will be upgraded for the LHC Run 3 and will be readout at 30 MHz, corresponding to the full inelastic collision rate, with major implications on the full software trigger and ...offline computing. If the current computing model and software framework are kept, the data storage capacity and computing power required to process data at this rate, and to generate and reconstruct equivalent samples of simulated events, will exceed the current capacity by at least one order of magnitude. A redesign of the software framework, including scheduling, the event model, the detector description and the conditions database, is needed to fully exploit the computing power of multi-, many-core architectures, and coprocessors. Data processing and the analysis model will also change towards an early streaming of different data types, in order to limit storage resources, with further implications for the data analysis workflows. Fast simulation options will allow to obtain a reasonable parameterization of the detector response in considerably less computing time. Finally, the upgrade of LHCb will be a good opportunity to review and implement changes in the domains of software design, test and review, and analysis workflow and preservation. In this contribution, activities and recent results in all the above areas are presented.
Abstract
Two of the elements of the Cabibbo–Kobayashi–Maskawa quark mixing matrix,
$$|V_{ub}|$$
|
V
ub
|
and
$$|V_{cb}|$$
|
V
cb
|
, are extracted from semileptonic
B
decays. The results of the
B
...factories, analysed in the light of the most recent theoretical calculations, remain puzzling, because for both
$$|V_{ub}|$$
|
V
ub
|
and
$$|V_{cb}|$$
|
V
cb
|
the exclusive and inclusive determinations are in clear tension. Further, measurements in the
$$\tau $$
τ
channels at Belle, Babar, and LHCb show discrepancies with the Standard Model predictions, pointing to a possible violation of lepton flavor universality. LHCb and Belle II have the potential to resolve these issues in the next few years. This article summarizes the discussions and results obtained at the MITP workshop held on April 9–13, 2018, in Mainz, Germany, with the goal to develop a medium-term strategy of analyses and calculations aimed at solving the puzzles. Lattice and continuum theorists working together with experimentalists have discussed how to reshape the semileptonic analyses in view of the much higher luminosity expected at Belle II, searching for ways to systematically validate the theoretical predictions in both exclusive and inclusive
B
decays, and to exploit the rich possibilities at LHCb.
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Data preservation in high energy physics Basaglia, T.; Bellis, M.; Blomer, J. ...
European physical journal. C, Particles and fields,
09/2023, Volume:
83, Issue:
9
Journal Article
Peer reviewed
Open access
Data preservation is a mandatory specification for any present and future experimental facility and it is a cost-effective way of doing fundamental research by exploiting unique data sets in the ...light of the continuously increasing theoretical understanding. This document summarizes the status of data preservation in high energy physics. The paradigms and the methodological advances are discussed from a perspective of more than ten years of experience with a structured effort at international level. The status and the scientific return related to the preservation of data accumulated at large collider experiments are presented, together with an account of ongoing efforts to ensure long-term analysis capabilities for ongoing and future experiments. Transverse projects aimed at generic solutions, most of which are specifically inspired by open science and FAIR principles, are presented as well. A prospective and an action plan are also indicated.
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We report the measurement of the Cabibbo-Kobayashi-Maskawa CP-violating angle γ through a Dalitz plot analysis of neutral D-meson decays to K(S)(0) π+ π- and K(S)(0) K+ K- produced in the processes ...B∓ → DK∓, B∓ D* K∓ with D* → Dπ(0), Dγ, and B∓ → DK*∓ with K*∓ → K(S)(0) π∓, using 468 million BB pairs collected by the BABAR detector at the PEP-II asymmetric-energy e+ e- collider at SLAC. We measure γ = (68 ± 14 ± 4 ± 3)° (modulo 180°), where the first error is statistical, the second is the experimental systematic uncertainty, and the third reflects the uncertainty in the description of the neutral D decay amplitudes. This result is inconsistent with γ = 0 (no direct CP violation) with a significance of 3.5 standard deviations.
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Superalloys are a potential material class for selection in some tribological systems, particularly those subjected to wear. When subject to cavitation erosion, the cobalt-based alloys are often ...applied. Surface treatments have been employed to improve the tribological resistance without loss of corrosion performance for several class of materials. In this context, the thermochemical treatment of low temperature plasma carbonitriding was carried out in a superalloy of the Co-Cr-Fe system in order to improve cavitation erosion resistance. The carbonitriding treatments were performed at temperature of 380 °C over a period of 3, 9 and 15 h. The gas mixture was composed of 72.5% H2, 25% N2 and 2.5% CH4. After the thermochemical treatment, phases formation was identified by X-ray diffraction and the glow discharge optical emission spectroscopy was used for mass concentration depth profiling of carbon and nitrogen. Cavitation erosion resistance of specimens were evaluated by a vibratory test. Mass losses were periodically measured as a function of exposure time during test. Specimens were evaluated in terms of mean depth of erosion, incubation time and mass loss. In addition, the cavitation erosion mechanism was investigated by scanning electron microscopy observation of damaged surfaces. S-phase formation was observed for all treatments. Results showed that low temperature plasma carbonitriding and the formation of expanded phase are effective to increase cavitation erosion resistance of the studied cobalt-based alloy when treatment was carried out during 3 and 9 h.
•Cavitation erosion resistance of the plasma carbonitrided Stellite 250 alloy was studied.•S-phase dual layer was formed after low-temperature plasma carbonitriding.•The thermochemical treatment improves the hardness of Stellite 250 alloy.•Low-temperature plasma carbonitriding performed at 380 °C during 3 and 9 h provided higher cavitation erosion resistance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We study the process e+e- -> pi+pi-pi+pi-gamma, with a photon emitted from the initial-state electron or positron, using 454.3 fb^-1 of data collected with the BABAR detector at SLAC, corresponding ...to approximately 260,000 signal events. We use these data to extract the non-radiative sigma(e+e- ->pi+pi-pi+pi-) cross section in the energy range from 0.6 to 4.5 Gev. The total uncertainty of the cross section measurement in the peak region is less than 3%, higher in precision than the corresponding results obtained from energy scan data.
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