We present a program to calculate the total cross section for top-quark pair production in hadronic collisions. The program takes into account recent theoretical developments such as approximate ...next-to-next-to-leading order perturbative QCD corrections and it allows for studies of the theoretical uncertainty by separate variations of the factorization and renormalization scales. In addition it offers the possibility to obtain the cross section as a function of the running top-quark mass. The program can also be applied to a hypothetical fourth quark family provided the QCD couplings are standard.
Program title: Hathor
Catalogue identifier: AEID_v1_0
Program summary URL:
http://cpc.cs.qub.ac.uk/summaries/AEID_v1_0.html
Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland
Licensing provisions: GNU GPL 3
No. of lines in distributed program, including test data, etc.: 5405
No. of bytes in distributed program, including test data, etc.: 327 718
Distribution format: tar.gz
Programming language: C++, Fortran, Java
Computer: Standard PCs (x86, x86_64 processors)
Operating system: Linux
RAM: 256 MB
Classification: 11.1
External routines: Interface to LHAPDF for the user's choice of parton distribution functions, see
http://projects.hepforge.org/lhapdf/
Nature of problem: Computation of total cross section in perturbative QCD.
Solution method: Numerical integration of hard parton cross section convoluted with parton distribution functions.
Running time: A few seconds to a few minutes on standard desktop PCs or notebooks, depending on the chosen options.
We present an up-to-date profile of the Cabibbo-Kobayashi-Maskawa matrix with emphasis on the interpretation of recent CP-violation results from the B factories. For this purpose, we review all ...relevant experimental and theoretical inputs from the contributing domains of electroweak interaction. We give the “standard” determination of the apex of the Unitarity Triangle, namely the Wolfenstein parameters \(\overline\rho\) and \(\overline\eta\), by means of a global CKM fit. The fit is dominated by the precision measurement of \(\sin 2 \beta\) by the B factories. A detailed numerical and graphical study of the impact of the results is presented. We propose to include \(\sin 2\alpha\) from the recent measurement of the time-dependent CP-violating asymmetries in \(B^0\to\rho^ + \rho^-\), using isospin relations to discriminate the penguin contribution. The constraint from \(\varepsilon^\prime/\varepsilon\) is discussed. We study the impact from the branching fraction measurement of the rare kaon decay \(K^ + \to\pi^ + \nu\overline\nu\), and give an outlook into the reach of a future measurement of \(K^0_L\to\pi^0\nu\overline\nu\). The B system is investigated in detail. We display the constraint on \(2\beta + \gamma\) and \(\gamma\) from \(B^0\to D^{(*)\pm}\pi^\mp\) and \(B^ + \to D^{(*)0}K^ + \) decays, respectively. A significant part of this paper is dedicated to the understanding of the dynamics of B decays into \(\pi\pi\), \(K\pi\), \(\rho\pi\), \(\rho\rho\) and modes related to these by flavor symmetry. Various phenomenological approaches and theoretical frameworks are discussed. We find a remarkable agreement of the \(\pi\pi\) and \(K\pi\) data with the other constraints in the unitarity plane when the hadronic matrix elements are calculated within QCD Factorization, where we apply a conservative treatment of the theoretical uncertainties. A global fit of QCD Factorization to all \(\pi\pi\) and \(K\pi\) data leads to precise predictions of the related observables. However sizable phenomenological power corrections are preferred. Using an isospin-based phenomenological parameterization, we analyze separately the \(B\to K\pi\) decays, and the impact of electroweak penguins in response to recent discussions. We find that the present data are not sufficiently precise to constrain either electroweak parameters or hadronic amplitude ratios. We do not observe any unambiguous sign of New Physics, whereas there is some evidence for potentially large non-perturbative rescattering effects. Finally we use a model-independent description of a large class of New Physics effects in both \(B^0\overline B^0\) mixing and B decays, namely in the \(b\to d\) and \(b\to s\) gluonic penguin amplitudes, to perform a new numerical analysis. Significant non-standard corrections cannot be excluded yet, however Standard Model solutions are favored in most cases. In the appendix to this paper we propose a frequentist method to extract a confidence level on \(\Delta m_s\) from the experimental information on \(B^0_s \overline B_s^0\) oscillation. In addition we describe a novel approach to combine potentially inconsistent measurements. All results reported in this paper have been obtained with the numerical analysis package CKMfitter, featuring the frequentist statistical approach Rfit.
The ATLAS experiment is going to replace the current Inner Detector with an all new inner tracker (ITk) in the ATLAS detector for HL-LHC at CERN. Silicon strip detectors cover the outer layers of the ...barrel and the endcap sections. We have designed and fabricated a prototype single-sided n+-in-p AC-coupled silicon strip sensor for the outer barrel layer with long strips (LS), ATLAS17LS. It is of the maximum allowable size to fit in a 6-in. silicon wafer, with an outer dimension of 9.80(width)×9.76(length)cm2. The sensor features two rows of LS strip segments, 4.83 cm strip length per segment, a strip pitch of 75.5 μm, and a slim edge design. We have implemented technology for high voltage operation of up to 1000V, with a good signal collection after irradiation fluence of 5.6 × 1014neq∕cm2at the end of HL-LHC operation.
We had two objectives for the ATLAS17LS fabrication: qualification of the sensor design and fabrication quality, and providing an adequate number of the sensors for prototyping the building blocks of the strip detector. The sensors were fabricated in 3 batches by HPK with standard wafers from the foundry (320 μm physical thickness). Additional 10 sensors were fabricated with a thinner active thickness of 240 μm to investigate the influence of active thickness on charge collection. Another additional 5 sensors, with special passivation to investigate the influence of passivation on humidity sensitivity. The visual inspection of fabricated sensors revealed an inadequacy that the designed metal width of 10 μm was too narrow. The initial measurements by the vendor showed that the sensors fulfilled the specifications: onset voltages of Microdischarge VMD above the operation voltage VOP (700V for the 1st and 2nd batches; 500V for the 3rd batch, which has improved the yield), leakage currents of < 0.1μA/cm2 at VOP, full depletion voltages VFD< 330V, and rates of bad strips <<1%.
Several recent studies performed on constraints of a fourth generation of quarks and leptons suffer from the ad-hoc assumption that 3 × 3 unitarity holds for the first three generations in the ...neutrino sector. Only under this assumption is one able to determine the Fermi constant
G
F
from the muon lifetime measurement with the claimed precision of
G
F
= 1.16637(1) × 10
−5
GeV
−2
. We study how well
G
F
can be extracted within the framework of four generations from leptonic and radiative μ and τ decays, as well as from
K
ℓ3
decays and leptonic decays of charged pions, and we discuss the role of lepton universality tests in this context. In the combined fit to leptonic and radiative μ and τ decays,
K
ℓ3
decays and leptonic decays of charged pions we find a p-value of 2.6 % for the fourth generation matrix element |
U
e
4
| = 0 of the neutrino mixing matrix. We emphasize that constraints on a fourth generation from quark and lepton flavour observables and from electroweak precision observables can only be obtained in a consistent way if these three sectors are considered simultaneously.
We report on a new approach to a global CKM matrix analysis taking into account most recent experimental and theoretical results. The statistical framework (Rfit) developed in this paper advocates ...frequentist statistics. Other approaches, such as Bayesian statistics or the 95% CL scan method are also discussed. We emphasize the distinction of a model testing and a model dependent, metrological phase in which the various parameters of the theory are estimated. Measurements and theoretical parameters entering the global fit are thoroughly discussed, in particular with respect to their theoretical uncertainties. Graphical results for confidence levels are drawn in various one and two-dimensional parameter spaces. Numerical results are provided for all relevant CKM parameterizations, the CKM elements and theoretical input parameters. Predictions for branching ratios of rare K and B meson decays are obtained. A simple, predictive SUSY extension of the Standard Model is discussed.
Current methods to extract the quark-mixing matrix element |
V
tb
| from single-top-production measurements assume that |
V
tb
|≫|
V
td
|,|
V
ts
|: top quarks decay into
b
quarks with 100 % branching ...fraction,
s
-channel single-top production is always accompanied by a
b
quark and initial-state contributions from
d
and
s
quarks in the
t
-channel production of single top quarks are neglected. Triggered by a recent measurement of the ratio
performed by the D0 collaboration, we consider a |
V
tb
| extraction method that takes into account non zero
d
- and
s
-quark contributions both in production and decay. We propose a strategy that allows to extract consistently and in a model-independent way the quark-mixing matrix elements |
V
td
|, |
V
ts
|, and |
V
tb
| from the measurement of
R
and from single-top measured event yields. As an illustration, we apply our method to the Tevatron data using a CDF analysis of the measured single-top event yield with two jets in the final state, one of which is identified as a
b
-quark jet. We constrain the |
V
tq
| matrix elements within a four-generation scenario by combining the results with those obtained from direct measurements in flavor physics and determine the preferred range for the top-quark decay width within different scenarios.
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