2,620 research outputs found
LHCb trigger streams optimization
The LHCb experiment stores around collision events per year. A
typical physics analysis deals with a final sample of up to events.
Event preselection algorithms (lines) are used for data reduction. Since the
data are stored in a format that requires sequential access, the lines are
grouped into several output file streams, in order to increase the efficiency
of user analysis jobs that read these data. The scheme efficiency heavily
depends on the stream composition. By putting similar lines together and
balancing the stream sizes it is possible to reduce the overhead. We present a
method for finding an optimal stream composition. The method is applied to a
part of the LHCb data (Turbo stream) on the stage where it is prepared for user
physics analysis. This results in an expected improvement of 15% in the speed
of user analysis jobs, and will be applied on data to be recorded in 2017.Comment: Submitted to CHEP-2016 proceeding
Unitary boundary pairs for isometric operators in Pontryagin spaces and generalized coresolvents
An isometric operator V in a Pontryagin space H is called standard, if its
domain and the range are nondegenerate subspaces in H. A description of
coresolvents for standard isometric operators is known and basic underlying
concepts that appear in the literature are unitary colligations and
characteristic functions. In the present paper generalized coresolvents of
non-standard Pontryagin space isometric operators are described. The methods
used in this paper rely on a new general notion of boundary pairs introduced
for isometric operators in a Pontryagin space setting. Even in the Hilbert
space case this notion generalizes the earlier concept of boundary triples for
isometric operators and offers an alternative approach to study operator valued
Schur functions without any additional invertibility requirements appearing in
the ordinary boundary triple approach.Comment: 42 page
Bitangential interpolation in generalized Schur classes
Bitangential interpolation problems in the class of matrix valued functions
in the generalized Schur class are considered in both the open unit disc and
the open right half plane, including problems in which the solutions is not
assumed to be holomorphic at the interpolation points. Linear fractional
representations of the set of solutions to these problems are presented for
invertible and singular Hermitian Pick matrices. These representations make use
of a description of the ranges of linear fractional transformations with
suitably chosen domains that was developed in a previous paper.Comment: Second version, corrected typos, changed subsection 5.6, 47 page
A functional model, eigenvalues, and finite singular critical points for indefinite Sturm-Liouville operators
Eigenvalues in the essential spectrum of a weighted Sturm-Liouville operator
are studied under the assumption that the weight function has one turning
point. An abstract approach to the problem is given via a functional model for
indefinite Sturm-Liouville operators. Algebraic multiplicities of eigenvalues
are obtained. Also, operators with finite singular critical points are
considered.Comment: 38 pages, Proposition 2.2 and its proof corrected, Remarks 2.5, 3.4,
and 3.12 extended, details added in subsections 2.3 and 4.2, section 6
rearranged, typos corrected, references adde
Using machine learning to speed up new and upgrade detector studies: a calorimeter case
In this paper, we discuss the way advanced machine learning techniques allow
physicists to perform in-depth studies of the realistic operating modes of the
detectors during the stage of their design. Proposed approach can be applied to
both design concept (CDR) and technical design (TDR) phases of future detectors
and existing detectors if upgraded. The machine learning approaches may speed
up the verification of the possible detector configurations and will automate
the entire detector R\&D, which is often accompanied by a large number of
scattered studies. We present the approach of using machine learning for
detector R\&D and its optimisation cycle with an emphasis on the project of the
electromagnetic calorimeter upgrade for the LHCb detector\cite{lhcls3}. The
spatial reconstruction and time of arrival properties for the electromagnetic
calorimeter were demonstrated.Comment: Talk presented on CHEP 2019 conferenc
Deep learning for inferring cause of data anomalies
Daily operation of a large-scale experiment is a resource consuming task,
particularly from perspectives of routine data quality monitoring. Typically,
data comes from different sub-detectors and the global quality of data depends
on the combinatorial performance of each of them. In this paper, the problem of
identifying channels in which anomalies occurred is considered. We introduce a
generic deep learning model and prove that, under reasonable assumptions, the
model learns to identify 'channels' which are affected by an anomaly. Such
model could be used for data quality manager cross-check and assistance and
identifying good channels in anomalous data samples. The main novelty of the
method is that the model does not require ground truth labels for each channel,
only global flag is used. This effectively distinguishes the model from
classical classification methods. Being applied to CMS data collected in the
year 2010, this approach proves its ability to decompose anomaly by separate
channels.Comment: Presented at ACAT 2017 conference, Seattle, US
Boundary triplets for skew-symmetric operators and the generation of strongly continuous semigroups
We give a self-contained and streamlined exposition of a generation theorem
for C0-semigroups based on the method of boundary triplets. We apply this
theorem to port-Hamiltonian systems where we discuss recent results appearing
in stability and control theory. We give detailed proofs and require only a
basic knowledge of operator and semigroup theory.Comment: 19 page
SchrĂśdinger operators with δ and δâ˛-potentials supported on hypersurfaces
Self-adjoint SchrĂśdinger operators with δ and δâ˛-potentials supported on a smooth compact hypersurface are defined explicitly via boundary conditions. The spectral properties of these operators are investigated, regularity results on the functions in their domains are obtained, and analogues of the BirmanâSchwinger principle and a variant of Kreinâs formula are shown. Furthermore, Schattenâvon Neumann type estimates for the differences of the powers of the resolvents of the SchrĂśdinger operators with δ and δâ˛-potentials, and the SchrĂśdinger operator without a singular interaction are proved. An immediate consequence of these estimates is the existence and completeness of the wave operators of the corresponding scattering systems, as well as the unitary equivalence of the absolutely continuous parts of the singularly perturbed and unperturbed SchrĂśdinger operators. In the proofs of our main theorems we make use of abstract methods from extension theory of symmetric operators, some algebraic considerations and results on elliptic regularity
Update of the Unitarity Triangle Analysis
We present the status of the Unitarity Triangle Analysis (UTA), within the
Standard Model (SM) and beyond, with experimental and theoretical inputs
updated for the ICHEP 2010 conference. Within the SM, we find that the general
consistency among all the constraints leaves space only to some tension
(between the UTA prediction and the experimental measurement) in BR(B -> tau
nu), sin(2 beta) and epsilon_K. In the UTA beyond the SM, we allow for New
Physics (NP) effects in (Delta F)=2 processes. The hint of NP at the 2.9 sigma
level in the B_s-\bar B_s mixing turns out to be confirmed by the present
update, which includes the new D0 result on the dimuon charge asymmetry but not
the new CDF measurement of phi_s, being the likelihood not yet released.Comment: 4 pages, 2 figures, Proceedings of the 35th International Conference
of High Energy Physics - ICHEP2010 (July 22-28, 2010, Paris
Spin-dependent recombination mechanisms for quintet bi-excitons generated through singlet fission
We investigate the physical mechanisms for spin-dependent recombination of a
strongly bound pair of triplet excitons generated by singlet fission and
forming a spin quintet (total spin of two) bi-exciton. For triplet excitons the
spin-dependent recombination pathways can involve intersystem crossing or
triplet-triplet annihilation back to the singlet ground state. However the
modeling of spin-dependent recombination for quintets is still an open
question. Here we introduce two theoretical models and compare their
predictions with the broadband optically detected magnetic resonance spectrum
of a long lived quintet bi-exciton with known molecular structure. This
spectrum measures the change in the fluorescence signal induced by microwave
excitation of each of the ten possible spin transitions within the quintet
manifold as function of the magnetic field. While most of the experimental
features can be reproduced for both models, the behavior of some of the
transitions is only consistent with the quintet spin-recombination model
inspired by triplet intersystem crossing which can reproduce accurately the
experimental two-dimensional spectrum with a small number of kinetic
parameters. Thus quantitative analysis of the broadband optically detected
magnetic resonance signal enables quantitative understanding of the dominant
spin-recombination processes and estimation of the out-of equilibrium spin
populations.Comment: optimization code available at https://github.com/yneter/ampodm
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