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Of all publications in the section: 32
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Article
Mironov A., Morozov A., Natanzon S. M. The European Physical Journal C - Particles and Fields. 2013. Vol. 73. No. 2. P. 1-10.

We review and explain an infinite-dimensional counterpart of the Hurwitz theory realization (Alexeevski and Natanzon, Math. Russ. Izv. 72:3-24, 2008) of algebraic open-closed-string model à la Moore and Lazaroiu, where the closed and open sectors are represented by conjugation classes of permutations and the pairs of permutations, i.e. by the algebra of Young diagrams and bipartite graphs, respectively. An intriguing feature of this Hurwitz string model is the coexistence of two different multiplications, reflecting the deep interrelation between the theory of symmetric and linear groups, S∞ and GL(∞).

Added: Mar 29, 2013
Article
Derkach D., Ustyuzhanin A., Likhomanenko T. The European Physical Journal C - Particles and Fields. 2016. Vol. 76. No. 7.

The oscillation frequency, TeV">TeVTeV. A combination of the two decay modes gives <span data-mathml="nsΔmd=(505.0±2.1±1.0)ns−1Δmd=(505.0±2.1±1.0)ns−1, where the first uncertainty is statistical and the second is systematic. This is the most precise single measurement of this parameter. It is consistent with the current world average and has similar precision.

 

Added: Oct 24, 2016
Article
Amburg N., Itoyama H., Mironov A. et al. The European Physical Journal C - Particles and Fields. 2020. Vol. 80. P. 471.

A novel functorial relationship in perturbative quantum field theory is pointed out that associates Feynman diagrams (FD) having no external line in one theory Th1Th1 with singlet operators in another one Th2Th2 having an additional U(N)U(N) symmetry and is illustrated by the case where Th1Th1 and Th2Th2 are respectively the rank r−1r−1 and the rank r complex tensor model. The values of FD in Th1Th1 agree with the large NN limit of the Gaussian average of those operators in Th2Th2. The recursive shift in rank by this FD functor converts numbers into vectors, then into matrices, then into rank 3 tensors and so on. This FD functor can straightforwardly act on the d dimensional tensorial quantum field theory (QFT) counterparts as well. In the case of rank 2-rank 3 correspondence, it can be combined with the geometrical pictures of the dual of the original FD, namely, equilateral triangulations (Grothendieck’s dessins d’enfant) to form a triality which may be regarded as a bulk-boundary correspondence.

Added: Sep 22, 2020
Article
Natanzon S. M., Mironov A., Morozov A. The European Physical Journal C - Particles and Fields. 2020. Vol. 80. No. 97. P. 1-16.

Spin Hurwitz numbers are related to characters of the Sergeev group, which are the expansion coefficients of the Q Schur functions, depending on odd times and on a subset of all Young diagrams. These characters involve two dual subsets: the odd partitions (OP) and the strict partitions (SP). The Q Schur functions Q_R with R\in SP are common eigenfunctions of cut-and-join operators W_Δwith Δ\in OP. The eigenvalues of these operators are the generalized Sergeev characters, their algebra is isomorphic to the algebra of Q Schur functions. Similarly to the case of the ordinary Hurwitz numbers, the generating function of spin Hurwitz numbers is a τ-function of an integrable hierarchy, that is, of the BKP type. At last, we discuss relations of the Sergeev characters with matrix models.

Added: Mar 2, 2020
Article
Аушев Т. А., Мизюк Р. В., Pakhlov P. et al. The European Physical Journal C - Particles and Fields. 2018. Vol. 78. No. 11. P. 1-8.

We report evidence for the charged charmed-strange baryon Ξ c(2930) + with a signal significance of 3.9σ with systematic errors included. The charged Ξ c(2930) + is found in its decay to KS0Λc+ in the substructure of B¯0→KS0Λc+Λ¯c- decays. The measured mass and width are [2942.3 ± 4.4 (stat.) ± 1.5 (syst.)] MeV/c2 and [14.8 ± 8.8 (stat.) ± 2.5 (syst.)] MeV, respectively, and the product branching fraction is B(B¯0→Ξc(2930)+Λ¯c-)B(Ξc(2930)+→K¯0Λc+)=[2.37±0.51(stat.)±0.31(syst.)]×10-4. We also measure B(B¯0→K¯0Λc+Λ¯c-)=[3.99±0.76(stat.)±0.51(syst.)]×10-4 with greater precision than previous experiments, and present the results of a search for the charmonium-like state Y(4660) and its spin partner, Yη, in the Λc+Λ¯c- invariant mass spectrum. No clear signals of the Y(4660) or Yη are observed and the 90% credibility level (C.L.) upper limits on their production rates are determined. These measurements are obtained from a sample of (772 ± 11) × 10 6BB¯ pairs collected at the Υ (4 S) resonance by the Belle detector at the KEKB asymmetric energy electron-positron collider. © 2018, The Author(s).

Added: Oct 28, 2020
Article
Godunov S., Rozanov A., M.I.Vysotsky et al. The European Physical Journal C - Particles and Fields. 2016. Vol. 76. No. 1. P. 1-6.

An extension of the Standard Model with an additional Higgs singlet is analyzed. Bounds on singlet admixture for the 125 GeV h boson from electroweak radiative corrections and data on h production and decays are obtained. The possibility of double h production enhancement at 14 TeV LHC due to a heavy Higgs contribution is considered.  

Added: Jan 25, 2018
Article
Motohashi H., Starobinsky Alexei A. The European Physical Journal C - Particles and Fields. 2017. Vol. 77. No. 8. P. 1-8.

The previously introduced class of two-parametric phenomenological inflationary models in general relativity in which the slow-roll assumption is replaced by the more general, constant-roll condition is generalized to the case of f(R) gravity. A simple constant-roll condition is defined in the original Jordan frame, and exact expressions for a scalaron potential in the Einstein frame, for a function f(R) (in the parametric form) and for inflationary dynamics are obtained. The region of the model parameters permitted by the latest observational constraints on the scalar spectral index and the tensor-to-scalar ratio of primordial metric perturbations generated during inflation is determined.

 

Added: Feb 15, 2018
Article
Shvydkin P., Glazov A., Olness F. et al. The European Physical Journal C - Particles and Fields. 2018. Vol. 78. No. 8. P. 1-14.

Fits to the final combined HERA deep-inelastic scattering cross-section data within the conventional DGLAP framework of QCD have shown some tension at low x and low Q2. A resolution of this tension incorporating ln(1/x)-resummation terms into the HERAPDF fits is investigated using the xFitter program. The kinematic region where this resummation is important is delineated. Such high-energy resummation not only gives a better description of the data, particularly of the longitudinal structure function FL, it also results in a gluon PDF which is steeply rising at low x for low scales, Q2≃2.5 GeV2, contrary to the fixed-order NLO and NNLO gluon PDF.

Added: Aug 7, 2018
Article
M. Borisyak, Derkach D., Ratnikov F. et al. The European Physical Journal C - Particles and Fields. 2017. Vol. 10. No. C77. P. 678-690.

A search for the decay K0S→μ+μ− is performed, based on a data sample of proton-proton collisions corresponding to an integrated luminosity of 3 fb−1, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The observed yield is consistent with the background-only hypothesis, yielding a limit on the branching fraction of B(K0S→μ+μ−)<0.8 (1.0)×10−9 at 90% (95%) confidence level. This result improves the previous upper limit on the branching fraction by an order of magnitude. 

Added: Oct 23, 2017
Article
Аушев Т. А., Мизюк Р. В., Pakhlov P. et al. The European Physical Journal C - Particles and Fields. 2018. Vol. 78. No. 8. P. 1-10.

We study bottomonium production in association with an η meson in e+e- annihilations near the Υ(5 S) , at a centre-of-mass energy of s=10.866 GeV. The results are based on the 121.4 fb- 1 data sample collected by the Belle experiment at the asymmetric-energy KEKB collider. Only the η meson is reconstructed and the missing-mass spectrum of η candidates is investigated. We observe the e+e-→ ηΥJ(1 D) process and find evidence for the e+e-→ ηΥ(2 S) process, while no significant signals of Υ(1 S) , hb(1 P) , nor hb(2 P) are found. Cross sections for the studied processes are reported. © 2018, The Author(s).

Added: Oct 28, 2020
Article
Derkach D., Guschin M., Kazeev N. et al. The European Physical Journal C - Particles and Fields. 2020. Vol. 80. No. 3. P. 1-23.

The cross-sections of 𝜓(2𝑆) meson production in proton-proton collisions at 𝑠√=13 TeV are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of 275 pb−1. The production cross-sections for prompt 𝜓(2𝑆) mesons and those for 𝜓(2𝑆) mesons from b-hadron decays (𝜓(2𝑆)-from- 𝑏) are determined as functions of the transverse momentum, 𝑝T, and the rapidity, y, of the 𝜓(2𝑆) meson in the kinematic range 2<𝑝T<20 GeV/𝑐 and 2.0<𝑦<4.5

. The production cross-sections integrated over this kinematic region are

𝜎( prompt 𝜓(2𝑆),13 TeV)=1.430±0.005 (stat)±0.099 (syst)μb,𝜎(𝜓(2𝑆)-from- 𝑏,13 TeV)=0.426±0.002 (stat)±0.030 (syst)μb.

A new measurement of 𝜓(2𝑆)

production cross-sections in pp collisions at 𝑠√=7 TeV is also performed using data collected in 2011, corresponding to an integrated luminosity of 614 pb−1. The integrated production cross-sections in the kinematic range 3.5<𝑝T<14 GeV/𝑐 and 2.0<𝑦<4.5

are

𝜎( prompt 𝜓(2𝑆),7 TeV)=0.471±0.001 (stat)±0.025 (syst)μb,𝜎(𝜓(2𝑆)-from- 𝑏,7 TeV)=0.126±0.001 (stat)±0.008 (syst)μb.

All results show reasonable agreement with theoretical calculations.

Added: Mar 11, 2020
Article
Derkach D., Guschin M., Kazeev N. et al. The European Physical Journal C - Particles and Fields. 2020. Vol. 80. No. 3. P. 185.

The cross-sections of 𝜓(2𝑆)ψ(2S) meson production in proton-proton collisions at 𝑠√=13 TeVs=13 TeV are measured with a data sample collected by the LHCb detector corresponding to an integrated luminosity of 275 pb−1275 pb−1. The production cross-sections for prompt 𝜓(2𝑆)ψ(2S) mesons and those for 𝜓(2𝑆)ψ(2S) mesons from b-hadron decays (𝜓(2𝑆)-from- 𝑏ψ(2S)-from- b) are determined as functions of the transverse momentum, 𝑝TpT, and the rapidity, y, of the 𝜓(2𝑆)ψ(2S) meson in the kinematic range 2<𝑝T<20 GeV/𝑐2<pT<20 GeV/c and 2.0<𝑦<4.52.0<y<4.5. The production cross-sections integrated over this kinematic region are

𝜎( prompt 𝜓(2𝑆),13 TeV)=1.430±0.005 (stat)±0.099 (syst)μb,𝜎(𝜓(2𝑆)-from- 𝑏,13 TeV)=0.426±0.002 (stat)±0.030 (syst)μb.σ( prompt ψ(2S),13 TeV)=1.430±0.005 (stat)±0.099 (syst)μb,σ(ψ(2S)-from- b,13 TeV)=0.426±0.002 (stat)±0.030 (syst)μb.

A new measurement of 𝜓(2𝑆)ψ(2S) production cross-sections in pp collisions at 𝑠√=7 TeVs=7 TeV is also performed using data collected in 2011, corresponding to an integrated luminosity of 614 pb−1614 pb−1. The integrated production cross-sections in the kinematic range 3.5<𝑝T<14 GeV/𝑐3.5<pT<14 GeV/c and 2.0<𝑦<4.52.0<y<4.5 are

𝜎( prompt 𝜓(2𝑆),7 TeV)=0.471±0.001 (stat)±0.025 (syst)μb,𝜎(𝜓(2𝑆)-from- 𝑏,7 TeV)=0.126±0.001 (stat)±0.008 (syst)μb.σ( prompt ψ(2S),7 TeV)=0.471±0.001 (stat)±0.025 (syst)μb,σ(ψ(2S)-from- b,7 TeV)=0.126±0.001 (stat)±0.008 (syst)μb.

All results show reasonable agreement with theoretical calculations.

Added: Dec 7, 2020
Article
Khachatryan V., Ratnikov F. The European Physical Journal C - Particles and Fields. 2016. Vol. 76. No. 10. P. 536.

A measurement of the decorrelation of azimuthal angles between the two jets with the largest transverse momenta is presented for seven regions of leading jet transverse momentum up to 2.2TeVTeV. The analysis is based on the proton-proton collision data collected with the CMS experiment at a centre-of-mass energy of 8TeVTeV corresponding to an integrated luminosity of 19.7fb−1fb−1. The dijet azimuthal decorrelation is caused by the radiation of additional jets and probes the dynamics of multijet production. The results are compared to fixed-order predictions of perturbative quantum chromodynamics (QCD), and to simulations using Monte Carlo event generators that include parton showers, hadronization, and multiparton interactions. Event generators with only two outgoing high transverse momentum partons fail to describe the measurement, even when supplemented with next-to-leading-order QCD corrections and parton showers. Much better agreement is achieved when at least three outgoing partons are complemented through either next-to-leading-order predictions or parton showers. This observation emphasizes the need to improve predictions for multijet production.

 

Added: Oct 21, 2016
Article
Khachatryan V., Ratnikov F. The European Physical Journal C - Particles and Fields. 2016. Vol. 76. No. 8. P. 469.

The differential cross section and charge asymmetry for inclusive pp→W±+X→μ±ν+Xpp→W±+X→μ±ν+Xproduction at s√=8TeVs=8TeV are measured as a function of muon pseudorapidity. The data sample corresponds to an integrated luminosity of 18.8fb−1fb−1 recorded with the CMS detector at the LHC. These results provide important constraints on the parton distribution functions of the proton in the range of the Bjorken scaling variable x from 10−310−3 to 10−110−1.

 

Added: Oct 21, 2016
Article
Aaboud M., Glazov A., et a. et al. The European Physical Journal C - Particles and Fields. 2016. Vol. 76. No. 12. P. 1-42.

he algorithms used by the ATLAS Collaboration to reconstruct and identify prompt photons are described. Measurements of the photon identification efficiencies are reported, using 4.9 fb−1 of pp collision data collected at the LHC at s√=7   TeV and 20.3 fb−1 at s√=8   TeV . The efficiencies are measured separately for converted and unconverted photons, in four different pseudorapidity regions, for transverse momenta between 10  GeV and 1.5  TeV . The results from the combination of three data-driven techniques are compared to the predictions from a simulation of the detector response, after correcting the electromagnetic shower momenta in the simulation for the average differences observed with respect to data. Data-to-simulation efficiency ratios used as correction factors in physics measurements are determined to account for the small residual efficiency differences. These factors are measured with uncertainties between 0.5% and 10% in 7  TeV data and between 0.5% and 5.6% in 8  TeV data, depending on the photon transverse momentum and pseudorapidity.

Added: Aug 7, 2018
Article
Ratnikov F. The European Physical Journal C - Particles and Fields. 2014. Vol. 74. No. 10. P. 3076.

Observation of the diphoton decay mode of the recently discovered Higgs boson and measurement of some of its properties are reported. The analysis uses the entire dataset collected by the CMS experiment in proton-proton collisions during the 2011 and 2012 LHC running periods. The data samples correspond to integrated luminosities of 5.1 fb-1fb-1 at s√=7TeVs=7TeV and 19.7 fb-1fb-1 at 8 TeVTeV  . A clear signal is observed in the diphoton channel at a mass close to 125 GeVGeV  with a local significance of 5.7σ5.7σ , where a significance of 5.2σ5.2σ is expected for the standard model Higgs boson. The mass is measured to be 124.70±0.34GeV=124.70±0.31(stat)±0.15(syst)GeV124.70±0.34GeV=124.70±0.31(stat)±0.15(syst)GeV, and the best-fit signal strength relative to the standard model prediction is 1.14+0.26−0.23=1.14±0.21(stat)+0.09−0.05(syst)+0.13−0.09(theo)1.14−0.23+0.26=1.14±0.21(stat)−0.05+0.09(syst)−0.09+0.13(theo) . Additional measurements include the signal strength modifiers associated with different production mechanisms, and hypothesis tests between spin-0 and spin-2 models.

Added: Oct 21, 2016
Article
Kononov Y., Morozov A. The European Physical Journal C - Particles and Fields. 2016. No. August.

A remarkable feature of Schur functions—the common eigenfunctions of cut-and-join operators from W∞W∞—is that they factorize at the peculiar two-parametric topological locus in the space of time variables, which is known as the hook formula for quantum dimensions of representations of Uq(SLN)Uq(SLN) and which plays a big role in various applications. This factorization survives at the level of Macdonald polynomials. We look for its further generalization to generalized Macdonald polynomials (GMPs), associated in the same way with the toroidal Ding–Iohara–Miki algebras, which play the central role in modern studies in Seiberg-Witten–Nekrasov theory. In the simplest case of the first-coproduct eigenfunctions, where GMP depend on just two sets of time variables, we discover a weak factorization—on a one- (rather than four-) parametric slice of the topological locus, which is already a very non-trivial property, calling for proof and better understanding.

 

Added: Sep 16, 2016
Article
Kamenshchik A. Y., Starobinsky Alexei A., Tronconi A. et al. The European Physical Journal C - Particles and Fields. 2018. Vol. 78. No. 3. P. 1-12.

We have considered the Pauli-Zeldovich mechanism for the cancellation of the ultraviolet divergences in vacuum energy. This mechanism arises because bosons and fermions give contributions of the opposite signs. In contrast with the preceding papers devoted to this topic wherein mainly free fields were studied, here we have taken their interactions into account to the lowest order of perturbation theory. We have constructed some simple toy models having particles with spin 0 and spin 1/2, where masses of the particles are equal while the interactions can be quite non-trivial.

Added: Jul 3, 2018
Article
Сапронов А. А., Bardin D. The European Physical Journal C - Particles and Fields. 2017. Vol. 77. No. 5. P. 1-53.

This report was prepared in the context of the LPCC Electroweak Precision Measurements at the LHC WG (https://lpcc.web.cern.ch/lpcc/index.php?page=electroweak_wg) and summarizes the activity of a subgroup dedicated to the systematic comparison of public Monte Carlo codes, which describe the Drell–Yan processes at hadron colliders, in particular at the CERN Large Hadron Collider (LHC). This work represents an important step towards the definition of an accurate simulation framework necessary for very high-precision measurements of electroweak (EW) observables such as the W boson mass and the weak mixing angle. All the codes considered in this report share at least next-to-leading-order (NLO) accuracy in the prediction of the total cross sections in an expansion either in the strong or in the EW coupling constant. The NLO fixed-order predictions have been scrutinized at the technical level, using exactly the same inputs, setup and perturbative accuracy, in order to quantify the level of agreement of different implementations of the same calculation. A dedicated comparison, again at the technical level, of three codes that reach next-to-next-to-leading-order (NNLO) accuracy in quantum chromodynamics (QCD) for the total cross section has also been performed. These fixed-order results are a well-defined reference that allows a classification of the impact of higher-order sets of radiative corrections. Several examples of higher-order effects due to the strong or the EW interaction are discussed in this common framework. Also the combination of QCD and EW corrections is discussed, together with the ambiguities that affect the final result, due to the choice of a specific combination recipe. All the codes considered in this report have been run by the respective authors, and the results presented here constitute a benchmark that should be always checked/reproduced before any high-precision analysis is conducted based on these codes. In order to simplify these benchmarking procedures, the codes used in this report, together with the relevant input files and running instructions, can be found in a repository at https://twiki.cern.ch/twiki/bin/view/Main/DrellYanComparison.

Added: Feb 25, 2018
Article
Godunov S., Machet B., M.I.Vysotsky. The European Physical Journal C - Particles and Fields. 2017. Vol. 77. No. 11. P. 2-12.

We re-examine the physics of supercritical nuclei, specially focusing on the scattering phase δ and its dependence on the energy ε of the diving electronic level, for which we give both exact and approximate formulas. The Coulomb potential Zα/r is rounded to the constant Zα/R for r<R. We confirm the resonant behavior of δ that we investigate in detail. In addition to solving the Dirac equation for an electron, we solve it for a positron, in the field of the same nucleus. This clarifies the interpretation of the resonances. Our results are compared with claims made in previous works.

Added: Jan 11, 2018
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