Phys. Lett. B

A search for long-lived particles was performed with data corresponding to an integrated luminosity of 2.6 fb −1 collected at a center-of-mass energy of 13 TeV by the CMS experiment in 2015. The analysis exploits two customized topological trigger algorithms, and uses the multiplicity of displaced jets to search for the presence of a signal decay occurring at distances between 1 and 1000 mm. The results can be interpreted in a variety of different models. For pair-produced long-lived particles decaying to two b quarks and two leptons with equal decay rates between lepton flavors, cross sections larger than 2.5 fb are excluded for proper decay lengths between 70–100 mm for a long-lived particle mass of 1130 GeV at 95% confidence. For a specific model of pair-produced, long-lived top squarks with R-parity violating decays to a b quark and a lepton, masses below 550–1130 GeV are excluded at 95% confidence for equal branching fractions between lepton flavors, depending on the squark decay length. This mass bound is the most stringent to date for top squark proper decay lengths greater than 3 mm.

Phys.Part.Nucl.

In frames of the nonlocal and nonpolynomial quantum theory of the one component scalar field in $D$-dimensional spacetime, stated by G.V. Efimov, the expansion of the $\mathcal{S}$-matrix is revisited for different interaction Lagrangians and for some kinds of Gaussian propagators modified by different ultraviolet form factors $F$ which depend on some length parameter $l$. The expansion of the $\mathcal{S}$-matrix is of the form of a grand canonical partition function of some $(D + N)$-dimensional ($N \geqslant 1$) classical gas with interaction. The toy model of the realistic quantum field theory (QFT) is considered where the $\mathcal{S}$-matrix is calculated in closed form. Then, the functional Schwinger–Dyson and Schrödinger equations for the $\mathcal{S}$-matrix in Efimov representation are derived. These equations play a central role in the present paper. The functional Schwinger–Dyson and Schrödinger equations in Efimov representation do not involve explicit functional derivatives but involve a shift of the field which is the $\mathcal{S}$-matrix argument. The asymptotic solutions of the Schwinger–Dyson equation are obtained in different limits. Also, the solution is found in one heuristic case allowing us to study qualitatively the behavior of the $\mathcal{S}$-matrix for an arbitrary finite value of its argument. Self-consistency equations, which arise during the process of derivation, are of a great interest. Finally, in the light of the discussion of QFT functional equations, ultraviolet form factors and extra dimensions, the connection with functional (in terms of the Wilson–Polchinski and Wetterich–Morris functional equations) and holographic renormalization groups (in terms of the functional Hamilton–Jacobi equation) is made. In addition the Hamilton–Jacobi equation is formulated in an unconventional way.

Phys. Rev. Lett.

Jet substructure observables have significantly extended the search program for physics beyond the standard model at the Large Hadron Collider. The state-of-the-art tools have been motivated by theoretical calculations, but there has never been a direct comparison between data and calculations of jet substructure observables that are accurate beyond leading-logarithm approximation. Such observables are significant not only for probing the collinear regime of QCD that is largely unexplored at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider. This Letter documents a measurement of the first jet substructure quantity at a hadron collider to be calculated at next-to-next-to-leading-logarithm accuracy. The normalized, differential cross section is measured as a function of log10ρ2, where ρ is the ratio of the soft-drop mass to the ungroomed jet transverse momentum. This quantity is measured in dijet events from 32.9  fb-1 of s=13  TeV proton-proton collisions recorded by the ATLAS detector. The data are unfolded to correct for detector effects and compared to precise QCD calculations and leading-logarithm particle-level Monte Carlo simulations.

Phys. Rev. D

The process e+e-→Ds*+Ds0*(2317)-+c.c. is observed for the first time with the data sample of 567  pb-1 collected with the BESIII detector operating at the BEPCII collider at a center-of-mass energy s=4.6  GeV. The statistical significance of the Ds0*(2317)± signal is 5.8σ and the mass is measured to be (2318.3±1.2±1.2)  MeV/c2. The absolute branching fraction B(Ds0*(2317)±→π0Ds±) is measured as 1.00−0.14+0.00(stat)−0.14+0.00(syst) for the first time. The uncertainties are statistical and systematic, respectively.

J. Phys. Conf. Ser.

Any time you modify an implementation within a program, change compiler version or operating system, you should also do regression testing. You can do regression testing by rerunning existing tests against the changes to determine whether this breaks anything that worked prior to the change and by writing new tests where necessary. At LHCb we have a huge codebase which is maintained by many people and can be run within different setups. Such situations lead to the crucial necessity to guide refactoring with a central profiling system that helps to run tests and find the impact of changes. In our work we present a software architecture and tools for running a profiling system. This system is responsible for systematically running regression tests, collecting and comparing results of these tests so changes between different setups can be observed and reported. The main feature of our solution is that it is based on a microservices architecture. Microservices break a large project into loosely coupled modules, which communicate with each other through simple APIs. Such modular architectural style helps us to avoid general pitfalls of monolithic architectures such as hard to understand a codebase as well as maintaining a large codebase and ineffective scalability. Our solution also allows to escape a complexity of microservices deployment process by using software containers and services management tools. Containers and service managers let us quickly deploy linked modules in development, production or in any other environments. Most of the developed modules are generic which means that the proposed architecture and tools can be used not only in LHCb but adopted for other experiments and companies.

J. Phys. Conf. Ser.

The ATLAS EventIndex has been running in production since mid-2015, reliably collecting information worldwide about all produced events and storing them in a central Hadoop infrastructure at CERN. A subset of this information is copied to an Oracle relational database for fast dataset discovery, event-picking, crosschecks with other ATLAS systems and checks for event duplication. The system design and its optimization is serving event picking from requests of a few events up to scales of tens of thousand of events, and in addition, data consistency checks are performed for large production campaigns. Detecting duplicate events with a scope of physics collections has recently arisen as an important use case. This paper describes the general architecture of the project and the data flow and operation issues, which are addressed by recent developments to improve the throughput of the overall system. In this direction, the data collection system is reducing the usage of the messaging infrastructure to overcome the performance shortcomings detected during production peaks; an object storage approach is instead used to convey the event index information, and messages to signal their location and status. Recent changes in the Producer/Consumer architecture are also presented in detail, as well as the monitoring infrastructure.

Phys. Lett. B

A search for gauge-mediated supersymmetry (SUSY) in final states with photons and large missing transverse momentum is presented. The data sample of pp collisions at s=13TeV was collected with the CMS detector at the CERN LHC and corresponds to an integrated luminosity of 35.9 fb −1 . Data are compared with models in which the lightest neutralino has bino- or wino-like components, resulting in decays to photons and gravitinos, where the gravitinos escape detection. The event selection is optimized for both electroweak (EWK) and strong production SUSY scenarios. The observed data are consistent with standard model predictions, and limits are set in the context of a general gauge mediation model in which gaugino masses up to 980 GeV are excluded at 95% confidence level. Gaugino masses below 780 and 950 GeV are excluded in two simplified models with EWK production of mass-degenerate charginos and neutralinos. Stringent limits are set on simplified models based on gluino and squark pair production, excluding gluino (squark) masses up to 2100 (1750) GeV depending on the assumptions made for the decay modes and intermediate particle masses. This analysis sets the highest mass limits to date in the studied EWK models, and in the considered strong production models when the mass difference between the gauginos and the squarks or gluinos is small.

Phys. Part. Nucl.

Borexino is continuing to take data and presenting the new results. The most recent Borexino results are discussed and plans for the nearest future are presented.

Fiz.Elem.Chast.Atom.Yadra

The differential cross section of the reaction pp → {pp}$_{s}$ π$^{0}$, where {pp}$_{s}$ is the proton pair in the$^{1}$ S$_{0}$ state at a small excitation energy E$_{pp}$ < 3 MeV, is calculated using the box diagram with the excitation of the Δ-isobar. The model demonstrates a clear bump observed in the experimental data at the beam energy of ∼0.6 GeV and the zero diproton outgoing angle, however, its absolute value strongly depends on the off-shell extrapolation of the πNΔ vertex factor and underestimates the data.

Phys. Part. Nucl.

We suggest a possible explanation of the reactor antineutrino anomaly derived from a covariant quantum field-theoretical approach to neutrino oscillations. Some disadvantages of the currently prevailing interpretation of the anomaly, based upon the sterile neutrino hypothesis are pointed out.

Phys. Part. Nucl.

This article presents the development of the A.M. Baldin approach using a description relativistic nuclear interactions in the four velocity space. This approach allows one to perform calculations of pion yields in hadron-hadron interactions in the central rapidity region depending on the transverse momentum. Results of our calculations have coincided with experimental data in a wide energy range with high precision. This approach gives a good description of the experimental results at high (LHC) and at lower energies (the Nuclotron).

Phys. Part. Nucl.

The old and new experimental studies of dibaryon resonances are reviewed, and their results are interpreted theoretically. Main emphasis is made on the research in this and related areas of relativistic nuclear physics carried out at the Joint Institute for Nuclear Research (JINR) in Dubna, starting from its foundation in mid-1950s. The dibaryon studies are shown to be pivotal for JINR together with the research in such related areas as the cumulative processes, subthreshold production of mesons, single and double pion production in NN collisions, and short-range NN correlations in nuclei.