Tue·Sep 5, 2017Tuesday·September 5, 2017

1. 01*

   Collision Energy Dependence of Moments of Net-Kaon Multiplicity Distributions at RHIC

   STAR Collaboration: L. Adamczyk · J. R. Adams · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · N. N. Ajitanand · I. Alekseev · D. M. Anderson · R. Aoyama · A. Aparin · D. Arkhipkin and 339 other authors

   Fluctuations of conserved quantities such as baryon number, charge, and strangeness are sensitive to the correlation length of the hot and dense matter created in relativistic heavy-ion collisions and can be used to search for the QCD critical point. We report the first measurements of the moments of net-kaon multiplicity distributions in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV. The collision centrality and energy dependence of the mean ($M$), variance (${\sigma }^2$), skewness ($S$), and kurtosis ($\kappa$) for net-kaon multiplicity distributions as well as the ratio ${\sigma }^2/M$ and the products $S\sigma$ and $\kappa {\sigma }^2$ are presented. Comparisons are made with Poisson and negative binomial baseline calculations as well as with UrQMD, a transport model (UrQMD) that does not include effects from the QCD critical point. Within current uncertainties, the net-kaon cumulant ratios appear to be monotonic as a function of collision energy.

   nucl-exhep-exhep-phnucl-thPLB(2018)·175 citations
2. 02*

   Projectile Fragmentation of relativistic nuclei in peripheral Collisions

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

   A study of multiplicity distribution of singly charged, doubly charged, multi charged projectile fragments and shower particles have been carried out for the peripheral collisions in 16O-emulsion,22Ne-emulsion and 28Si-emulsion interactions at an incident momentum of (4.1-4.5) AGeV/c. Events having no target fragments have been designated as peripheral collision events. Percentage of peripheral events has been found to increase with the increase of projectile mass. Dispersion of the multiplicity distribution and its dependence on projectile mass for projectile fragments and shower particles has also been investigated. Dependence of average multiplicity of projectile fragments and shower particles on the mass of the projectile beam has been studied. Study of different fragmentation mode during the emission of multi charged projectile fragments has also been carried out.

   nucl-exEur.Phys.J.Plus(2019)·9 citations
3. 03*

   Importance of d-wave contributions in the charge symmetry breaking reaction $dd\to {}^4\text{He}{\pi }^0$

   P. Adlarson🇵🇱 · W. Augustyniak🇵🇱 · W. Bardan🇵🇱 · M. Bashkanov🇬🇧 · F.S. Bergmann🇩🇪 · M. Berłowski🇵🇱 · A. Bondar🇷🇺 · M. Büscher🇩🇪 · H. Calén🇸🇪 · I. Ciepał🇵🇱 · H. Clement🇩🇪 · E. Czerwiński🇵🇱 and 80 other authors

   This letter reports a first quantitative analysis of the contribution of higher partial waves in the charge symmetry breaking reaction $dd\to {}^4\text{He}{\pi }^0$ using the WASA-at-COSY detector setup at an excess energy of $Q=60$ MeV. The determined differential cross section can be parametrized as $\text{d}\sigma /\text{d}\Omega =a+b{\cos }^2{\theta }^{\ast }$, where ${\theta }^{\ast }$ is the production angle of the pion in the center-of-mass coordinate system, and the results for the parameters are $a=\left(1.55\pm 0.46(\text{stat}{)}_{-0.8}^{+0.32}(\text{syst})\right)$ pb/sr and $b=\left(13.1\pm 2.1(\text{stat}{)}_{-2.7}^{+1.0}(\text{syst})\right)$ pb/sr. The data are compatible with vanishing p-waves and a sizable d-wave contribution. This finding should strongly constrain the contribution of the $\Delta$ isobar to the $dd\to {}^4\text{He}{\pi }^0$ reaction and is, therefore, crucial for a quantitative understanding of quark mass effects in nuclear production reactions.

   nucl-exPLB(2018)·3 citations
4. 04*

   Tracking performance in high multiplicities environment at ALICE

   David Rohr (for the ALICE collaboration)🇨🇭

   In LHC Run 3, ALICE will increase the data taking rate significantly to 50\,kHz continuous read out of minimum bias Pb-Pb events. This challenges the online and offline computing infrastructure, requiring to process 50 times as many events per second as in Run 2, and increasing the data compression ratio from 5 to 20. Such high data compression is impossible by lossless ZIP-like algorithms, but it must use results from online reconstruction, which in turn requires online calibration. These important online processing steps are the most computing-intense ones, and will use GPUs as hardware accelerators. The new online features are already under test during Run 2 in the High Level Trigger (HLT) online processing farm. The TPC (Time Projection Chamber) tracking algorithm for Run 3 is derived from the current HLT online tracking and is based on the Cellular Automaton and Kalman Filter. HLT has deployed online calibration for the TPC drift time, which needs to be extended to space charge distortions calibration. This requires online reconstruction for additional detectors like TRD (Transition Radiation Detector) and TOF (Time Of Flight). We present prototypes of these developments, in particular a data compression algorithm that achieves a compression factor of~9 on Run 2 TPC data, and the efficiency of online TRD tracking. We give an outlook to the challenges of TPC tracking with continuous read out.

   ↳ physics.ins-detnucl-ex13 citations
5. 05*

   Most Strange Dibaryon from Lattice QCD

   Shinya Gongyo🇯🇵 · Kenji Sasaki🇯🇵 · Sinya Aoki🇯🇵 · Takumi Doi🇯🇵 · Tetsuo Hatsuda🇯🇵 · Yoichi Ikeda🇯🇵 · Takashi Inoue🇯🇵 · Takumi Iritani🇯🇵 · Noriyoshi Ishii🇯🇵 · Takaya Miyamoto🇯🇵 · Hidekatsu Nemura🇯🇵

   The $\Omega \Omega$ system in the ${}^1{S}_0$ channel (the most strange dibaryon) is studied on the basis of the (2+1)-flavor lattice QCD simulations with a large volume (8.1 fm)${}^3$ and nearly physical pion mass $m_{\pi }\simeq 146$ MeV at a lattice spacing $a\simeq 0.0846$ fm. We show that lattice QCD data analysis by the HAL QCD method leads to the scattering length $a_0=4.6(6){(}_{-0.5}^{+1.2})\mathrm{fm}$, the effective range $r_{\mathrm{eff}}=1.27(3){(}_{-0.03}^{+0.06})\mathrm{fm}$ and the binding energy $B_{\Omega \Omega }=1.6(6){(}_{-0.6}^{+0.7})\mathrm{MeV}$. These results indicate that the $\Omega \Omega$ system has an overall attraction and is located near the unitary regime. Such a system can be best searched experimentally by the pair-momentum correlation in relativistic heavy-ion collisions.

   ↳ hep-lathep-exhep-phnucl-ex+1PRL(2018)·154 citations
6. 06*

   Abundance Uncertainties Obtained With the PizBuin Framework For Monte Carlo Reaction Rate Variations

   T. Rauscher🇬🇧 · N. Nishimura🇬🇧 · G. Cescutti · R. Hirschi🇬🇧 · A. St.J. Murphy🇬🇧

   Uncertainties in nucleosynthesis models originating from uncertainties in astrophysical reaction rates were estimated in a Monte Carlo variation procedure. Thousands of rates were simultaneously varied within individual, temperature-dependent errors to calculate their combined effect on final abundances. After a presentation of the method, results from application to three different nucleosynthesis processes are shown: the $\gamma$-process and the s-process in massive stars, and the main s-process in AGB stars (preliminary results). Thermal excitation of nuclei in the stellar plasma and the combined action of several reactions increase the final uncertainties above the level of the experimental errors. The total uncertainty, on the other hand, remains within a factor of two even in processes involving a large number of unmeasured rates, with some notable exceptions for nuclides whose production is spread over several stellar layers and for s-process branchings.

   ↳ astro-ph.SRastro-ph.HEnucl-exnucl-thAIP Conf.Proc.(2018)·2 citations
7. 07*

   Exclusive pion-induced Drell-Yan process at J-PARC for accessing the nucleon GPDs and soft nonfactorizable mechanism

   Kazuhiro Tanaka (Juntendo Univ.)🇯🇵

   Generalized parton distributions (GPDs) encoding multidimensional information of hadron partonic structure appear as the building blocks in a factorized description of hard exclusive reactions. The nucleon GPDs have been accessed by deeply virtual Compton scattering and deeply virtual meson production with lepton beam. A complementary probe with hadron beam is shown to be the exclusive pion-induced Drell-Yan process, ${\pi }^{-}p\to {\mu }^{+}{\mu }^{-}n$, as demonstrated by recent theoretical advances on describing this process in terms of QCD factorization as the partonic subprocess convoluted with the nucleon GPDs and the pion distribution amplitudes, and by the feasibility study for its measurement via a spectrometer at the High Momentum Beamline being constructed at J-PARC in Japan. We also discuss the possible soft partonic mechanisms beyond the QCD factorization framework, and present an estimate of the soft mechanisms at J-PARC kinematics, making use of dispersion relations and quark-hadron duality. Realization of the measurement of the exclusive pion-induced Drell-Yan process at J-PARC will provide a new test of QCD descriptions of a novel class of hard exclusive reactions, and also offer the possibility of experimentally accessing nucleon GPDs at large timelike virtuality.

   ↳ hep-phhep-exnucl-exnucl-thPoS(2018)·2 citations
8. 08*

   Double Gamow-Teller transitions and its relation to neutrinoless $\beta \beta$ decay

   Noritaka Shimizu🇯🇵 · Javier Menéndez🇯🇵 · Kentaro Yako🇯🇵

   We study the double Gamow-Teller (DGT) strength distribution of ${}^{48}$Ca with state-of-the-art large-scale nuclear shell model calculations. Our analysis shows that the centroid energy of the DGT giant resonance depends mostly on the isovector pairing interaction, while the resonance width is more sensitive to isoscalar pairing. Pairing correlations are also key in neutrinoless $\beta \beta$ ($0\nu \beta \beta$) decay. We find a simple relation between the centroid energy and width of the ${}^{48}$Ca DGT giant resonance and %the value of the $0\nu \beta \beta$ decay nuclear matrix element. More generally, we observe a very good linear correlation between the DGT transition to the ground state of the final nucleus and the $0\nu \beta \beta$ decay matrix element. The correlation, which originates on the dominant short-range character of both transitions, extends to heavier systems including several $\beta \beta$ emitters, and also holds in energy-density functional results. Our findings suggest that DGT experiments can be a very valuable tool to obtain information on the value of $0\nu \beta \beta$ decay nuclear matrix elements.

   ↳ nucl-thhep-exhep-phnucl-exPRL(2018)·103 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.