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Of all publications in the section: 97
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Article
Aushev T., Mizuk R., Pakhlov P. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2019. Vol. 100. No. 3. P. 1-8.

We present the first measurements of the absolute branching fractions of Ξ+c decays into Ξ−π+π+ and pKπ+ final states. Our analysis is based on a data set of (772±11)×106 BB¯ pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB e+e− collider. We measure the absolute branching fraction of B¯0→Λ¯−cΞ+c with the Ξ+c recoiling against Λ¯−c in B¯0 decays resulting in B(B¯0→Λ¯−cΞ+c)=[1.16±0.42(stat.)±0.15(syst.)]×10−3 . We then measure the product branching fractions B(B¯0→Λ¯−cΞ+c)B(Ξ+c→Ξ−π+π+) and B(B¯0→Λ¯−cΞ+c)B(Ξ+cpKπ+) . Dividing these product branching fractions by B¯0→Λ¯−cΞ+c yields: B(Ξ+c→Ξ−π+π+)=[2.86±1.21(stat.)±0.38(syst.)]% and B(Ξ+cpKπ+)=[0.45±0.21(stat.)±0.07(syst.)]% . Our result for B(Ξ+c→Ξ−π+π+) can be combined with Ξ+c branching fractions measured relative to Ξ+c→Ξ−π+π+ to set the absolute scale for many Ξ+c branching fractions.

Added: Jun 5, 2020
Article
Arzymatov K., Belavin V., Boldyrev A. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2020. Vol. 102. No. 5. P. 1-11.

The first observation of the decay B0→D0¯D0K+π− is reported using proton-proton collision data corresponding to an integrated luminosity of 4.7  fb−1 collected by the LHCb experiment in 2011, 2012 and 2016. The measurement is performed in the full kinematically allowed range of the decay outside of the D*− region. The ratio of the branching fraction relative to that of the control channel B0→D*−D0K+ is measured to be R=(14.2±1.1±1.0)%, where the first uncertainty is statistical and the second is systematic. The absolute branching fraction of B0→D0¯D0K+π− decays is thus determined to be B(B0→D0¯D0K+π−)=(3.50±0.27±0.26±0.30)×10−4, where the third uncertainty is due to the branching fraction of the control channel. This decay mode is expected to provide insights to spectroscopy and the charm-loop contributions in rare semileptonic decays.

Added: Dec 6, 2020
Article
Arzymatov K., Belavin V., Borisyak M. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2020. Vol. 102. No. 11.

The decay Λ0b→ηc(1S)pK− is observed for the first time using a data sample of proton-proton collisions, corresponding to an integrated luminosity of 5.5  fb−1, collected with the LHCb experiment at a center-of-mass energy of 13 TeV. The branching fraction of the decay is measured, using the Λ0b→J/ψpK− decay as a normalization mode, to be B(Λ0b→ηc(1S)pK−)=(1.06±0.16±0.06+0.22−0.19)×10−4, where the quoted uncertainties are statistical, systematic and due to external inputs, respectively. A study of the ηc(1S)p mass spectrum is performed to search for the Pc(4312)+ pentaquark state. No evidence is observed and an upper limit of B(Λ0b→Pc(4312)+K−)×B(Pc(4312)+→ηc(1S)p)B(Λ0b→ηc(1S)pK−)<0.24 is obtained at the 95% confidence level.

Added: Sep 1, 2021
Article
Arbuzova E. V., Dolgov A. D., Novikov V.A. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2016. Vol. 94. No. 12. P. 123501-1-123501-17.

 

General features of spontaneous baryogenesis are studied. The relation between the time derivative of the (pseudo) Goldstone field and the baryonic chemical potential is revisited. It is shown that this relation essentially depends upon the representation chosen for the fermionic fields with nonzero baryonic number (quarks). The calculations of the cosmological baryon asymmetry are based on the kinetic equation generalized to the case of nonstationary background. The effects of the finite interval of the integration over time are also taken into consideration. All these effects combined lead to a noticeable deviation of the magnitude of the baryon asymmetry from the canonical results.

 

 

 

Added: Feb 8, 2018
Article
Calderon R., Felbacq D., Gannouji R. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2019. Vol. 100. No. 8. P. 083503.

We perform here a global analysis of the growth index γ behavior from deep in the matter era till the far future. For a given cosmological model in general relativity (GR) or in modified gravity, the value of γ(Ω_m) is unique when the decaying mode of scalar perturbations is negligible. However, γ_∞, the value of γ in the asymptotic future, is unique even in the presence of a non-negligible decaying mode today. Moreover, γ becomes arbitrarily large deep in the matter era. Only in the limit of a vanishing decaying mode do we get a finite γ , from the past to the future in this case. We find further a condition for γ(Ω_m) to be monotonically decreasing (or increasing). This condition can be violated inside GR for varying w_{DE} though generically γ(Ω_m) will be monotonically decreasing (like ΛCDM ), except in the far future and past. A bump or a dip in Geff can also lead to a significant and rapid change in the slope dγ/dΩ_m . On a ΛCDM background, a γ substantially lower (higher) than 0.55 with a negative (positive) slope reflects the opposite evolution of G_{eff}. In Dvali-Gabadadze-Porrati (DGP) models, γ(Ω_m) is monotonically increasing except in the far future. While DGP gravity becomes weaker than GR in the future and w^{DGP}→ -1 , we still get γ_∞^{DGP} = γ_∞^{ΛCDM} = 2/3 . In contrast, despite G_eff^{DGP}→G in the past, γ does not tend to its value in GR because dG_{eff}^{DGP}/ dΩ_m |_{-∞} ≠ 0.

Added: Feb 18, 2020
Article
Akhmedov E., Popov F., Godazgar H. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2016. Vol. 93. P. 024029.

We study the expectation value of the energy momentum tensor during thin shell collapse for a massive, real, scalar field theory. At tree-level, we find thermal, Hawking-type, behaviour for the energy flux. Using the Schwinger-Keldysh technique, we calculate two-loop corrections to the tree-level correlation functions and show that they exhibit secular growth, suggesting the breakdown of the perturbation theory.

Added: Jan 22, 2016
Article
Akhmedov E., Федор П., Слепухин В. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2013. Vol. 88. No. 2. P. 024021.

We study massive real scalar $\phi^4$ theory in the expanding Poincare patch of de Sitter space. We calculate the leading two-loop infrared contribution to the two-point function in this theory. We do that for the massive fields both from the principal and complementary series. As can be expected at this order light fields from the complementary series show stronger infrared effects than the heavy fields from the principal one. For the principal series, unlike the complementary one, we can derive the kinetic equation from the system of Dyson--Schwinger equation, which allows us to sum up the leading infrared contributions from all loops. We find two peculiar solutions of the kinetic equation. One of them describes the stationary Gibbons--Hawking-type distribution for the density per comoving volume. Another solution shows explosive (square root of the pole in finite proper time) growth of the particle number density per comoving volume. That signals the possibility of the destruction of the expanding Poincare patch even by the very massive fields. We conclude with the consideration of the infrared divergences in global de Sitter space and in its contracting Poincare patch.

Added: Aug 31, 2013
Article
Akhmedov E., Buividovich P. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2008. Vol. 78. P. 104005.
Added: Feb 26, 2013
Article
Valba O. V., Gorsky A. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2021. Vol. 103. No. 10.

We discuss numerically the nonperturbative effects in exponential random graphs which are analogue of eigenvalue instantons in matrix models. The phase structure of exponential random graphs with chemical potential for C4 μ4 and degree preserving constraint is clarified. The first order phase transition at critical value of chemical potential for C4 μRRG 4 into bipartite phase with a formation of fixed number of bipartite clusters is found for ensemble of random regular graphs (RRG). We consider the similar phase transition in mean field version of combinatorial quantum gravity based of the Ollivier graph curvature for RRG supplemented with hard-core constraint and show that a order of a phase transition at μCRRG 4 and the structure of emerging phase depend on a vertex degree d in RRG. For d ¼ 3 the bipartite closed ribbon emerges at μ4 > μCRRG 4 while for d > 3 the ensemble of isolated or weakly interacting hypercubes supplemented with the bipartite closed ribbon gets emerged at the first order phase transition with a clearcut hysteresis. If the additional connectedness condition is imposed the phase at μ4 > μCRRG 4 gets identified as the closed chain of weakly coupled hypercubes. Since the ground state of isolated hypercube is the thermofield double we suggest that the dual holographic picture involves multiboundary wormholes. Treating RRG as a model of a Hilbert space for a interacting many-body system we discuss the patterns of the Hilbert space fragmentation at the phase transition. We also briefly comment on a possible relation of the found phase transition to the problem of holographic interpretation of a partial deconfinement transition in the gauge theories.

Added: Aug 17, 2021
Article
Сапронов А. А., Aad G., Glazov A. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2017. Vol. 96. No. 7. P. 072002-1-072002-36.

Jet energy scale measurements and their systematic uncertainties are reported for jets measured with the ATLAS detector using proton-proton collision data with a center-of-mass energy of s=13  TeV, corresponding to an integrated luminosity of 3.2  fb-1 collected during 2015 at the LHC. Jets are reconstructed from energy deposits forming topological clusters of calorimeter cells, using the anti-kt algorithm with radius parameter R=0.4. Jets are calibrated with a series of simulation-based corrections and in situ techniques. In situ techniques exploit the transverse momentum balance between a jet and a reference object such as a photon, Z boson, or multijet system for jets with 20<pT<2000  GeV and pseudorapidities of |η|<4.5, using both data and simulation. An uncertainty in the jet energy scale of less than 1% is found in the central calorimeter region (|η|<1.2) for jets with 100<pT<500  GeV. An uncertainty of about 4.5% is found for low-pT jets with pT=20  GeV in the central region, dominated by uncertainties in the corrections for multiple proton-proton interactions. The calibration of forward jets (|η|>0.8) is derived from dijet pT balance measurements. For jets of pT=80  GeV, the additional uncertainty for the forward jet calibration reaches its largest value of about 2% in the range |η|>3.5 and in a narrow slice of 2.2<|η|<2.4.

Added: Aug 7, 2018
Article
M.I.Vysotsky, Zhemchugov E. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2016. Vol. 93. No. 9. P. 094029-1-094029-9.

In an experiment currently being performed at the Institute for High Energy Physics, Serpukhov, Russia, a beam of charged kaons is directed on a copper target. In the electromagnetic field of the target nuclei, two reactions occur: K γ → K π0 and Kγ→Kπ+. A peculiar distinction between these two reactions is that there is a chiral anomaly contribution in the former reaction, but not in the latter. This contribution can be directly seen through comparison of the cross sections of these reactions near the threshold. We derive expressions for these cross sections taking into account the anomaly and the contribution of the lightest vector mesons.

Added: Jan 23, 2018
Article
Derkach D., Guschin M., Kazeev N. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2019. Vol. 100. No. 3. P. 031102-1-031102-11.

The production fractions of ¯B0s and Λ0b hadrons, normalized to the sum of B− and ¯B0 fractions, are measured in 13 TeV pp collisions using data collected by the LHCb experiment, corresponding to an integrated luminosity of 1.67  fb−1. These ratios, averaged over the b hadron transverse momenta from 4 to 25 GeV and pseudorapidity from 2 to 5, are 0.122±0.006 for ¯B0s, and 0.259±0.018 for Λ0b, where the uncertainties arise from both statistical and systematic sources. The Λ0b ratio depends strongly on transverse momentum, while the ¯B0s ratio shows a mild dependence. Neither ratio shows variations with pseudorapidity. The measurements are made using semileptonic decays to minimize theoretical uncertainties. In addition, the ratio of D+ to D0 mesons produced in the sum of ¯B0 and B− semileptonic decays is determined as 0.359±0.006±0.009, where the uncertainties are statistical and systematic.

Added: Mar 11, 2020
Article
Аушев Т. А., Мизюк Р. В., Pakhlova G. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2019. Vol. 100. No. 1. P. 1-9.

We report a measurement of the branching fraction and final-state asymmetry for the B0?KS0K±p± decays. The analysis is based on a data sample of 711 fb-1 collected at the ?(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain a branching fraction of (3.60±0.33±0.15)×10-6 and a final-state asymmetry of (-8.5±8.9±0.2)%, where the first uncertainties are statistical and the second are systematic. Hints of peaking structures are found in the differential branching fractions measured as functions of Dalitz variables. © 2019 authors. Published by the American Physical Society.

Added: Oct 28, 2020
Article
Аушев Т. А., Мизюк Р. В., Pakhlov P. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2018. Vol. 97. No. 3. P. 1-8.

Using a data sample of 980 fb-1 of e+e- annihilation data taken with the Belle detector operating at the KEKB asymmetric-energy e+e- collider, we report the results of a study of the decays of the Ωc0 charmed baryon into hadronic final states. We report the most precise measurements to date of the relative branching fractions of the Ωc0 into Ω-π+π0, Ω-π+π-π+, Ξ-K-π+π+, and Ξ0K-π+, as well as the first measurements of the branching fractions of the Ωc0 into Ξ-K̄0π+, Ξ0K̄0, and ΛK̄0K̄0, all with respect to the Ω-π+ decay. In addition, we investigate the resonant substructure of these modes. Finally, we present a limit on the branching fraction for the decay Ωc0→Σ+K-K-π+. © 2018 authors.

Added: Oct 28, 2020
Article
Аушев Т. А., Мизюк Р. В., Pakhlov P. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2020. P. 1-11.

We report branching fraction measurements of four decay modes of the Λ+c baryon, each of which includes an η meson and a Λ baryon in the final state, and all of which are measured relative to the Λ+cpKpi+ decay mode. The results are based on a 980 fb−1 data sample collected by the Belle detector at the KEKB asymmetric-energy e+e− collider. Two decays, ηΣ0π+ and Λ(1670)π+, are observed for the first time, while the measurements of the other decay modes, Λ+cηΛπ+ and ηΣ(1385)+, are more precise than those made previously. We obtain B(Λ+cηΛπ+)/B(Λ+cpKπ+) = 0.293±0.003±0.014, B(Λ+cηΣ0π+)/B(Λ+cpKπ+) = 0.120±0.006±0.006, B(Λ+c→Λ(1670)π+)×B(Λ(1670)→ηΛ)/B(Λ+cpKπ+) = (5.54±0.29±0.73)×10−2, and B(Λ+cηΣ(1385)+)/B(Λ+cpKπ+) = 0.192±0.006±0.016. The mass and width of the Λ(1670) are also precisely determined to be 1674.3±0.8±4.9 MeV/c2 and 36.1±2.4±4.8 MeV, respectively, where the uncertainties are statistical and systematic, respectively.

Added: Nov 27, 2020
Article
Аушев Т. А., Мизюк Р. В., Pakhlov P. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2018. Vol. 98. No. 11. P. 1-29.

We report measurements of sin2β and cos2β using a time-dependent Dalitz plot analysis of B0→D(∗)h0 with D→KS0π+π- decays, where the light unflavored and neutral hadron h0 is a π0, η, or ω meson. The analysis uses a combination of the final data sets of the BaBar and Belle experiments containing 471×106 and 772×106 BB pairs collected at the (4S) resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. We measure sin2β=0.80±0.14(stat)±0.06(syst)±0.03(model) and cos2β=0.91±0.22(stat)±0.09(syst)±0.07(model). The result for the direct measurement of the angle is β=(22.5±4.4(stat)±1.2(syst)±0.6(model))°. The last quoted uncertainties are due to the composition of the D0→KS0π+π- decay amplitude model, which is newly established by a Dalitz plot amplitude analysis of a high-statistics e+e-→cc data sample as part of this analysis. We find the first evidence for cos2β>0 at the level of 3.7 standard deviations. The measurement excludes the trigonometric multifold solution π/2-β=(68.1±0.7)° at the level of 7.3 standard deviations and therefore resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle. The hypothesis of β=0° is ruled out at the level of 5.1 standard deviations, and thus CP violation is observed in B0→D(∗)h0 decays. The measurement assumes no direct CP violation in B0→D(∗)h0 decays. © 2018 authors. Published by the American Physical Society.

Added: Oct 28, 2020
Article
Ratnikov F., Ustyuzhanin A., Derkach D. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2019. Vol. 100. No. 11. P. 112006.

The production fraction of the B−c meson with respect to the sum of B− and B¯0 mesons is measured in both 7 and 13 TeV center-of-mass energy pppp collisions produced by the Large Hadron Collider (LHC), using the LHCb detector. The rate, approximately 3.7 per mille, does not change with energy, but shows a transverse momentum dependence. The B−c − Bc+ production asymmetry is also measured, and is consistent with zero within the determined statistical and systematic uncertainties of a few percent.

Added: Sep 16, 2020
Article
A. Boldyrev, D. Derkach, M. Hushchyn et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2019. Vol. 100. No. 11. P. 112006-1-112006-17.

The production fraction of the B−c meson with respect to the sum of B− and ¯B0 mesons is measured in both 7 and 13 TeV center-of-mass (c.m.) energy pp collisions produced by the Large Hadron Collider (LHC), using the LHCb detector. The rate, approximately 3.7 per mille, does not change with energy, but shows a transverse momentum dependence. The B−c−B+c production asymmetry is also measured and is consistent with zero within the determined statistical and systematic uncertainties of a few percent.

Added: Feb 20, 2020
Article
Аушев Т. А., Мизюк Р. В., Pakhlov P. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2018. Vol. 98. No. 1. P. 1-9.

We report a measurement of the branching fractions of the decays B→D(∗)πν. The analysis uses 772×106 BB. pairs produced in e+e-→(4S) data recorded by the Belle experiment at the KEKB asymmetric-energy e+e- collider. The tagging B meson in the decay is fully reconstructed in a hadronic decay mode. On the signal side, we reconstruct the decay B→D(∗)πν(=e,μ). The measured branching fractions are B(B+→D-π++ν)=[4.55±0.27 (stat.)±0.39 (syst.)]×10-3, B(B0→D.0π-+ν)=[4.05±0.36 (stat.)±0.41 (syst.)]×10-3, B(B+→D∗-π++ν)=[6.03±0.43 (stat.)±0.38 (syst.)]×10-3, and B(B0→D.∗0π-+ν)=[6.46±0.53 (stat.)±0.52 (syst.)]×10-3. These are in good agreement with the current world-average values. © 2018 authors. Published by the American Physical Society.

Added: Oct 28, 2020
Article
Boldyrev A., Derkach D., Guschin M. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2020. Vol. 102. No. 1. P. 012011.

A measurement of the branching fraction of the decay B0s→K0SK0S is performed using proton–proton collision data corresponding to an integrated luminosity of 5  fb−1 collected by the LHCb experiment between 2011 and 2016. The branching fraction is determined to be B(B0s→K0SK0S)=[8.3±1.6(stat)±0.9(syst)±0.8(norm)±0.3(fs/fd)]×10−6, where the first uncertainty is statistical, the second is systematic, and the third and fourth are due to uncertainties on the branching fraction of the normalization mode B0→ϕK0S and the ratio of hadronization fractions fs/fd. This is the most precise measurement of this branching fraction to date. Furthermore, a measurement of the branching fraction of the decay B0→K0SK0S is performed relative to that of the B0s→K0SK0S channel, and is found to be B(B0→K0SK0S)B(B0s→K0SK0S)=[7.5±3.1(stat)±0.5(syst)±0.3(fs/fd)]×10−2.

Added: Sep 16, 2020
Article
Аушев Т. А., Мизюк Р. В., Pakhlov P. et al. Physical Review D - Particles, Fields, Gravitation and Cosmology. 2019. Vol. 100. No. 5. P. 1-32.

We present a new measurement of the Cabibbo-Kobayashi-Maskawa matrix element |Vcb| from B0→D∗-ℓ+νℓ decays, reconstructed with the full Belle data set of 711 fb-1 integrated luminosity. Two form factor parametrizations, originally conceived by the Caprini-Lellouch-Neubert (CLN) and the Boyd, Grinstein and Lebed (BGL) groups, are used to extract the product F(1)ηEW|Vcb| and the decay form factors, where F(1) is the normalization factor and ηEW is a small electroweak correction. In the CLN parametrization we find F(1)ηEW|Vcb|=(35.06±0.15±0.56)×10-3, ρ2=1.106±0.031±0.007, R1(1)=1.229±0.028±0.009, R2(1)=0.852±0.021±0.006. For the BGL parametrization we obtain F(1)ηEW|Vcb|=(34.93±0.23±0.59)×10-3, which is consistent with the world average when correcting for F(1)ηEW. The branching fraction of B0→D∗-ℓ+νℓ is measured to be B(B0→D∗-ℓ+νℓ)=(4.90±0.02±0.16)%. We also present a new test of lepton flavor universality violation in semileptonic B decays, B(B0→D∗-e+ν)B(B0→D∗-μ+ν)=1.01±0.01±0.03. The errors quoted correspond to the statistical and systematic uncertainties, respectively. This is the most precise measurement of F(1)ηEW|Vcb| and form factors to date and the first experimental study of the BGL form factor parametrization in an experimental measurement. © 2019 authors. Published by the American Physical Society.

Added: Oct 28, 2020