The LHCb experiment at CERN has decided to optimise its physics reach by removing the first level hardware trigger for 2020 and beyond. In addition to requiring fully redesigned front-end electronics ...this design creates interesting challenges for the data-acquisition and the rest of the online computing system. Such a system can only be realized within realistic cost using as much off-the-shelf hardware as possible. Relevant technologies evolve very quickly and thus the system design is architecture-centred and tries to avoid to depend too much on specific technologies. In this paper we describe the design, the motivations for various choices and the current favoured options for the implementation, and the status of the R&D. We will cover the back-end readout, which contains the only custom-made component, the event-building, the event-filter infrastructure, and storage.
We discuss tests of the charged Higgs sector of the Two Higgs Doublet Model (2HDM) of Type II in the light of recent flavour physics data. Particular attention is paid to recent measurement of purely ...leptonic decays of heavy-light mesons, which depart more or less significantly from the Standard Model (SM) predictions. We derive constraints on the parameters of the 2HDM type II from leptonic and semileptonic $\Delta F=1$ decays as well as loop processes ($b \to s \gamma$ or $Z\to\bar{b}b$) sensitive to charged Higgs contributions. The outcome of this work is that while 2HDM Type II can fit individual observable through fine-tuning schemes, in a combined analysis it does not perform better than the SM by favouring a decoupling solution. Assuming that 2HDM Type II is realized in Nature, constraints on its parameters ($m_{H^+}$ and $\tan \beta$) are derived. A limit on the charged Higgs mass $m_{H^+} > 304 {\rm GeV}$ at 95% CL is obtained irrespective of the value of $\tan \beta$. This limit is dominated by the $b\to s \gamma$ branching ratio measurement. All results have been obtained with the \ckmfitter analysis package, featuring the frequentist statistical approach \rfit to handle theoretical uncertainties.
We perform model-independent statistical analyses of three scenarios accommodating new physics (NP) in Delta F = 2 flavor-changing neutral current amplitudes. In a scenario in which NP in B sub(d) - ...B sub(d) mixing and B sub(s) - B sub(s) mixing is uncorrelated, we find the parameter point representing the standard model disfavored by 2.4 standard deviations. However, recent LHCb data on B sub(s) neutral meson mixing forbid a good accommodation of the DO data on the semileptonic CP asymmetry A sub(SL). We introduce a fourth scenario with NP in both (ProQuest: Formulae and/or non-USASCII text omitted) and (ProQuest: Formulae and/or non-USASCII text omitted), which can accommodate all data. We discuss the viability of this possibility and emphasize the importance of separate measurements of the CP asymmetries in semileptonic B sub(d) and B sub(s) decays. All results have been obtained with the CKMfitter analysis package, featuring the frequentisi statistical approach and using Rfit to handle theoretical uncertainties.
Anatomy of new physics in B - B ¯ mixing Lenz, A.; Nierste, U.; Charles, J. ...
Physical review. D, Particles, fields, gravitation, and cosmology,
02/2011, Letnik:
83, Številka:
3
Journal Article
B, D and K decays Buchalla, G.; Komatsubara, T. K.; Muheim, F. ...
European physical journal. C, Particles and fields (Print),
09/2008, Letnik:
57, Številka:
1-2
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
The present report documents the results of Working Group 2:
B
,
D
and
K
decays, of the workshop on Flavor in the Era of the LHC, held at CERN from November 2005 through March 2007.
With the advent ...of the LHC, we will be able to probe New Physics (NP) up to energy scales almost one order of magnitude larger than it has been possible with present accelerator facilities. While direct detection of new particles will be the main avenue to establish the presence of NP at the LHC, indirect searches will provide precious complementary information, since most probably it will not be possible to measure the full spectrum of new particles and their couplings through direct production. In particular, precision measurements and computations in the realm of flavor physics are expected to play a key role in constraining the unknown parameters of the Lagrangian of any NP model emerging from direct searches at the LHC.
The aim of Working Group 2 was twofold: on the one hand, to provide a coherent up-to-date picture of the status of flavor physics before the start of the LHC; on the other hand, to initiate activities on the path towards integrating information on NP from high-
p
T
and flavor data.
This report is organized as follows: in Sect. 1, we give an overview of NP models, focusing on a few examples that have been discussed in some detail during the workshop, with a short description of the available computational tools for flavor observables in NP models. Section 2 contains a concise discussion of the main theoretical problem in flavor physics: the evaluation of the relevant hadronic matrix elements for weak decays. Section 3 contains a detailed discussion of NP effects in a set of flavor observables that we identified as “benchmark channels” for NP searches. The experimental prospects for flavor physics at future facilities are discussed in Sect. 4. Finally, Sect. 5 contains some assessments on the work done at the workshop and the prospects for future developments.
A sensitivity study on the measurement of the CKM angle from decays is conducted using the D-meson reconstructed in the quasi flavour-specific modes , , and , as well as CP-eigenstate modes and , ...where the notation corresponds to a or meson. The LHCb experiment is presented as a use case. A statistical uncertainty of approximately can be achieved with the collision data collected in the LHCb experiment from 2011 to 2018. The sensitivity to should be of the order after accumulating 23 fb-1 of collision data by 2025, whereas it is expected to improve further by 300 fb-1 by the second half of the 2030 decade. The accuracy is dependent on the strong parameters and , which together with describe the interference between the leading amplitudes of the decays.
The B0, B0s, B+ and Λ0b hadron production asymmetries are measured using a data sample corresponding to an integrated luminosity of 3.0 fb−1, collected by the LHCb experiment in proton-proton ...collisions at centre-of-mass energies of 7 and 8 TeV. The measurements are performed as a function of transverse momentum and rapidity of the b hadrons within the LHCb detector acceptance. The overall production asymmetries, integrated over transverse momentum and rapidity, are also determined.
Our knowledge of the quark-mixing matrix and of CP violation has been tremendously improved thanks to the B factories and Tevatron: the KM mechanism is the dominant source of CP violation at the ...electroweak scale. LHCb is one of the six experiments being constructed on the Large Hadron Collider accelerator at CERN. It is a next generation of flavor-physics experiments which will perform precision tests of CP violation and study rare phenomena to unveil physics beyond the Standard Model, if any, in the interactions of charm- and beauty-hadron decays. The current build status of the detector is given followed by selected topics of the expected physics reach.
The production cross-section of J/ψ pairs is measured using a data sample of pp collisions collected by the LHCb experiment at a centre-of-mass energy of s√=13TeV, corresponding to an integrated ...luminosity of 279±11pb−1. The measurement is performed for J/ψ mesons with a transverse momentum of less than 10GeV/c in the rapidity range 2.0<y<4.5. The production cross-section is measured to be 13.5±0.9±0.8nb. The first uncertainty is statistical, and the second is systematic. The differential cross-sections as functions of several kinematic variables of the J/ψ pair are measured and compared to theoretical predictions.
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