Tue·Feb 20, 2018Tuesday·February 20, 2018

1. 01*

   Neutron lifetime, dark matter and search for sterile neutrino

   A. P. Serebrov🇷🇺 · R.M. Samoilov🇷🇺 · I.A. Mitropolsky🇷🇺 · A.M. Gagarsky🇷🇺

   A review is focused on experimental measurements on neutron lifetime. The latest measurements with a gravitational trap (PNPI NRC KI) and a magnetic trap (LANL, USA) confirmed PNPI result of 2005. The results of measurements with storage of ultra cold neutrons are in agreement, yet, there is discrepancy with a beam experiment by $3.5\sigma$ (1% of decay probability), which is discussed in literature as "neutron anomaly" along with the ideas of explaining it by decay into dark matter partially. The second part of the paper is devoted to so called "reactor antineutrino anomaly", which refers to deficiency of the measured flux of antineutrino from reactor in respect to the calculated flux by $3\sigma$(deviation by 6.6%). Specific feature of the proposal in this paper lies in the fact that both anomalies can be accounted for by one and the same phenomenon of oscillation in baryon sector between a neutron and a neutron of dark matter $n\to n^{\prime }$ with mass $m_{n^{\prime }}$, somewhat less than mass $m_n$ of an ordinary neutron. Calculations of the proposed model require one free parameter: mass difference $m_n-m_{n^{\prime }}$ if one normalizes probability of oscillations for a free neutron on "neutron anomaly" 1%, then, having succeeded to interpret 6.6% of neutron anomaly in calculations, one can determine mass difference. According to preliminary estimations, the mass difference is $m_n-m_{n^{\prime }}\approx$ 3 MeV. However, the analysis of cumulative yields of isotopes occurs in fission fragments was performed and it does not confirm possibility of existence of additional decay channel with emission of dark matter neutron with mass difference $m_n-m_{n^{\prime }}\approx$ 3 MeV. The result of the analysis is the conclusion that for mirror neutrons the region of the mass difference $m_n-m_{n^{\prime }}\ge$ 3 MeV is closed. The region of the mass difference $m_n-m_{n^{\prime }}\le$ 2 MeV turned out to be not closed.

   nucl-ex19 citations
2. 02*

   Electroweak probes with ATLAS

   Alexander Milov (for the ATLAS Collaboration)🇮🇱

   Measuring electroweak bosons in relativistic heavy ion collisions at high energy provide an opportunity to understand temporal evolution of the quark-gluon plasma created in such collisions by constraining the initial state of the interaction. Due to lack of color charges the bosons and or particles produced in their leptonic decays are unaffected by the quark-gluon plasma and therefore preserve the information about the very early stage of the collision when they were born. This singles electroweak bosons as a unique and very interesting class of observables in heavy ion collisions. The ATLAS experiment at LHC measures production of electroweak bosons in pp, p+Pb, and Pb + Pb collisions systems. A review of the existing results is given in this proceeding that includes studies made with isolated photons to constraint kinematic properties and flavour composition of associated jets, measurements of W and Z bosons used to estimate nuclear modification of parton distribution function and the production rates of the bosons used to verify geometric models implied to estimate event centrality. A novel analysis on measuring two-particle correlations in pp collisions where the Z boson is registered is also discussed in the proceeding. This is the first attempt to break into the initial geometry of the pp collisions by constraining the impact parameter with a hard scattering process. It shows that the strength of the two particle correlations in such collision is 1.08+/-0.06 above the inclusive. To make the measurement ATLAS solves the technical problem of measuring the underlying event in high pileup condition.

   nucl-exPoS(2019)·0 citations
3. 03*

   Acoustic scaling of linear and mode-coupled anisotropic flow; implications for precision extraction of the specific shear viscosity

   Peifeng Liu🇺🇸 · Roy A. Lacey (SUNY Stony Brook Chemistry Dept & SUNY Stony Brook Physics Dept.)🇺🇸

   The ${\mathrm{n}}^{\mathrm{th}}$-order linear flow coefficients ${\mathrm{v}}_{\mathrm{n}}^{\mathrm{L}}(\mathrm{n}=2,3,4,5)$, and the corresponding nonlinear mode-coupled ($\mathrm{mc}$) coefficients ${\mathrm{v}}_{4,(2,2)}^{\mathrm{mc}}$, ${\mathrm{v}}_{5,(2,3)}^{\mathrm{mc}}$, ${\mathrm{v}}_{6,(3,3)}^{\mathrm{mc}}$ and ${\mathrm{v}}_{6,(2,2,2)}^{\mathrm{mc}}$, are studied for Pb+Pb collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=2.76$ TeV. Both sets of coefficients indicate a common acoustic scaling pattern of exponential viscous modulation, with a rate proportional to the square of the harmonic numbers and the mean transverse momenta (respectively), and inversely proportional to the cube root of the charged particle multiplicity ($({\mathrm{N}}_{\mathrm{ch}}{)}^{1/3}$), that characterizes the dimensionless size of the systems produced in the collisions. These patterns and their associated scaling parameters, provide new stringent constraints for eccentricity independent estimates of the specific shear viscosity ($\eta /s$) and the viscous correction to the thermal distribution function for the matter produced in the collisions. They also give crucial constraints for extraction of the initial-state eccentricity spectrum.

   nucl-exnucl-thPRC(2018)·31 citations
4. 04*

   Differential Cross Section for $\gamma d\to \omega d$ using CLAS at Jefferson Lab

   T. Chetry (1 and 2) · K. Hicks (1 and 2) · N. Compton (1 and 2) · M. Sargsian (3) ((1) Ohio University, (2) CLAS Collaboration, (3) Florida International University)

   The cross section for coherent $\omega$-meson photoproduction off the deuteron has been measured for the first time as a function of the momentum transfer $t=(P_{\gamma }-P_{\omega }{)}^2$ and photon energy $E_{\gamma }$ using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The cross sections are measured in the energy range $1.4<E_{\gamma }<3.4$ GeV. A model based on $\omega -N$ rescattering is consistent with the data at low and intermediate momentum transfer, $|t|$. For $2.8<E_{\gamma }<3.4$ GeV, the total cross-section of $\omega -N$ scattering, based on fits within the framework of the Vector Meson Dominance model, is in the range of 30-40 mb.

   nucl-exhep-exPLB(2018)·6 citations
5. 05*

   Multifractal analysis of charged particle multiplicity distribution in the framework of Renyi entropy

   Swarnapratim Bhattacharyya🇮🇳 · Maria Haiduc🇷🇴 · Alina Tania Neagu🇷🇴 · Elena Firu🇷🇴

   A study of multifractality and multifractal specific heat has been carried out for the produced shower particles in nuclear emulsion detector for 16O-AgBr, 28Si-AgBr and 32S-AgBr interactions at 4.5AGeV/c in the framework of Renyi entropy. Experimental results have been compared with the prediction of Ultra Relativistic Quantum Molecular Dynamics (UrQMD) model. Our analysis reveals the presence of multifractality in the multiparticle production process in high energy nucleus-nucleus interactions. Degree of multifractality is found to be higher for the experimental data and it increases with the increase of projectile mass. The investigation of quark-hadron phase transition in the multiparticle production in 16O-AgBr, 28Si-AgBr and 32S-AgBr interactions at 4.5 AGeV/c in the framework of Ginzburg-Landau theory from the concept of multifractality has also been presented. Evidence of constant multifractal specific heat has been obtained for both experimental and UrQMD simulated data.

   nucl-exAdv.High Energy Phys.(2018)·4 citations
6. 06*

   Twist-3 GPDs in Deeply-Virtual Compton Scattering

   Fatma Aslan🇺🇸 · Matthias Burkardt🇺🇸 · Cédric Lorcé🇫🇷 · Andreas Metz🇺🇸 · Barbara Pasquini🇮🇹

   The sub-leading power of the scattering amplitude for deeply-virtual Compton scattering (DVCS) off the nucleon contains leading-twist and twist-3 generalized parton distributions (GPDs). We point out that in DVCS, at twist-3 accuracy, one cannot address any individual twist-3 GPD. This complication appears on top of the deconvolution issues familiar from the twist-2 DVCS amplitude. Accessible are exclusively linear combinations involving both vector and axial-vector twist-3 GPDs. This implies, in particular, that the (kinetic) orbital angular momentum of quarks can hardly be constrained by twist-3 DVCS observables. Moreover, using the quark-target model, we find that twist-3 GPDs can be discontinuous. The discontinuities however cancel in the DVCS amplitude, which further supports the hypothesis of factorization at twist-3 accuracy.

   ↳ hep-phhep-exnucl-exPRD(2018)·35 citations
7. 07*

   Theoretical analysis on the $K^{-}{}^3\text{He}\to \Lambda pn$ reaction for the $\bar{K}NN$ bound-state search in the J-PARC E15 experiment

   Takayasu Sekihara (1) · Eulogio Oset (2) · Angels Ramos (3) ((1) JAEA, Ibaraki, (2) Valencia U. & Valencia U., IFIC, (3) Barcelona U. & ICC, Barcelona U.)

   We theoretically analyze the $K^{-}{}^3\text{He}\to \Lambda pn$ reaction for the $\bar{K}NN$ bound-state search in the J-PARC E15 experiment. We find that, by detecting a fast and forward neutron in the final state, an almost on-shell $\bar{K}$ is guaranteed, which is essential to make a bound state with two nucleons from ${}^3\text{He}$. Then, this almost on-shell $\bar{K}$ can bring a signal of the $\bar{K}NN$ bound state in the $\Lambda p$ invariant-mass spectrum, although it inevitably brings a kinematic peak above the $\bar{K}NN$ threshold as well. As a consequence, we predict two peaks across the $\bar{K}NN$ threshold in the spectrum: the lower peak coming from the $\bar{K}NN$ bound state, and the higher one originating from the kinematics.

   ↳ nucl-thhep-phnucl-exPoS(2018)·4 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.