Tue·Nov 20, 2018Tuesday·November 20, 2018

1. 01*

   Observation of a Be double-Lambda hypernucleus in the J-PARC E07 experiment

   H. Ekawa🇯🇵 · K. Agari🇯🇵 · J. K. Ahn🇰🇷 · T. Akaishi🇯🇵 · Y. Akazawa🇰🇷 · S. Ashikaga🇯🇵 · B. Bassalleck🇺🇸 · S. Bleser🇩🇪 · Y. Endo🇯🇵 · Y. Fujikawa🇯🇵 · N. Fujioka🇯🇵 · M. Fujita🇮🇹 and 91 other authors

   A double-$\Lambda$ hypernucleus, ${}_{\Lambda \Lambda }\mathrm{Be}$, was observed by the J-PARC E07 collaboration in nuclear emulsions tagged by the $(K^{-},K^{+})$ reaction. This event was interpreted as a production and decay of ${}_{\Lambda \Lambda }^{10}\mathrm{Be}$, ${}_{\Lambda \Lambda }^{11}\mathrm{Be}$, or ${}_{\Lambda \Lambda }^{12}{\mathrm{Be}}^{\ast }$ via ${\Xi }^{-}$ capture in ${}^{16}\mathrm{O}$. By assuming the capture in the atomic 3D state, the binding energy of two $\Lambda$ hyperons($B_{\Lambda \Lambda }$) of these double-$\Lambda$ hypernuclei are obtained to be $15.05\pm 0.11\mathrm{MeV}$, $19.07\pm 0.11\mathrm{MeV}$, and $13.68\pm 0.11\mathrm{MeV}$, respectively. Based on the kinematic fitting, ${}_{\Lambda \Lambda }^{11}\mathrm{Be}$ is the most likely explanation for the observed event.

   nucl-exPTEP(2019)·55 citations
2. 02*

   Search for the ${\Sigma }^{\ast }$ state in ${\Lambda }_c^{+}\to {\pi }^{+}{\pi }^0{\pi }^{-}{\Sigma }^{+}$ decay by triangle singularity

   Ju-Jun Xie🇨🇳 · Eulogio Oset🇪🇸

   A ${\Sigma }^{\ast }$ resonance with spin-parity $J^P=1/2^{-}$ and mass in the vicinity of the $\bar{K}N$ threshold has been predicted in the unitary chiral approach and inferred from the analysis of CLAS data on the $\gamma p\to K^{+}{\pi }^0{\Sigma }^0$ reaction. In this work, based on the dominant Cabibbo favored weak decay mechanism, we perform a study of ${\Lambda }_c^{+}\to {\pi }^{+}{\pi }^0{\Sigma }^{\ast }$ with the possible ${\Sigma }^{\ast }$ state decaying into ${\pi }^{-}{\Sigma }^{+}$ through a triangle diagram. This process is initiated by ${\Lambda }_c^{+}\to {\pi }^{+}{\bar{K}}^{\ast }N$, then the ${\bar{K}}^{\ast }$ decays into $\bar{K}\pi$ and $\bar{K}N$ produce the ${\Sigma }^{\ast }$ through a triangle loop containing ${\bar{K}}^{\ast }N\bar{K}$ which develops a triangle singularity. We show that the ${\pi }^{-}{\Sigma }^{+}$ state is generated from final state interaction of $\bar{K}N$ in $S$-wave and isospin $I=1$, and the ${\Lambda }_c^{+}\to {\pi }^{+}{\pi }^0{\pi }^{-}{\Sigma }^{+}$ decay can be used to study the possible ${\Sigma }^{\ast }$ state around the $\bar{K}N$ threshold. The proposed decay mechanism can provide valuable information on the nature of the ${\Sigma }^{\ast }$ resonance and can in principle be tested by facilities such as LHCb, BelleII and BESIII.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2019)·27 citations
3. 03*

   Nucleon form factors and root-mean-square radii on a (10.8 fm${)}^4$ lattice at the physical point

   Eigo Shintani🇯🇵 · Ken-Ichi Ishikawa🇯🇵 · Yoshinobu Kuramashi🇯🇵 · Shoichi Sasaki🇯🇵 · Takeshi Yamazaki🇯🇵

   We present the nucleon form factors and root-mean-square (RMS) radii measured on a (10.8 fm${)}^4$ lattice at the physical point. We compute the form factors at small momentum transfer region in $q^2\le 0.102$ GeV${}^2$ with the standard plateau method choosing four source-sink separation times $t_{\mathrm{sep}}$ from 0.84 to 1.35 fm to examine the possible excited state contamination. We obtain the electric and magnetic form factors and their RMS radii for not only the isovector channel but also the proton and neutron ones without the disconnected diagram. We also obtain the axial-vector coupling and the axial radius from the axial-vector form factor. We find that these three form factors do not show large $t_{\mathrm{sep}}$ dependence in our lattice setup. On the other hand, the induced pseudoscalar and pseudoscalar form factors show the clear effects of the excited state contamination, which affect the generalized Goldberger-Treiman relation.

   ↳ hep-lathep-phnucl-exnucl-thPRD(2019)·132 citations
4. 04*

   Studying parton correlations via double parton scatterings in associated quarkonium production at the LHC and the Tevatron

   Nodoka Yamanaka🇫🇷 · Jean-Philippe Lansberg🇫🇷 · Hua-Sheng Shao🇫🇷 · Yu-Jie Zhang🇨🇳

   Quarkonium production in proton-proton (pp) collision provides interesting means to study the parton content and their correlations in the proton. Recent LHC and Tevatron data of J/psi + Z, J/psi + W and J/psi +J/psi production suggest the relevance of double parton scatterings (DPSs) as opposed to single parton scatterings (SPSs). In this proceedings contribution, we review the corresponding SPS contributions and discuss their upper limits set up by quark-hadron duality. These allow us to perform an improved extraction of the DPS yields and of their implications.

   ↳ hep-phhep-exnucl-exnucl-thPoS(2019)·1 citation
5. 05*

   Non-identical particle femtoscopy in Pb$-$Pb collisions at $\sqrt{{\text{s}}_{\mathrm{NN}}}=2.76$ TeV measured with ALICE

   Ashutosh Kumar Pandey (for the ALICE Collaboration)🇮🇳

   Two-particle femtoscopic correlations between non-identical charged particles for different charge combinations are measured in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV with ALICE at the LHC. The three-dimensional two-particle correlation functions are studied in different centrality bins. The femtoscopic source size parameter ($R_{Out}$) and emission asymmetry ($\mu$) are extracted. It is observed that the average source size of the system and emission asymmetry between particles increase from peripheral to central events.

   ↳ hep-exnucl-exPoS(2019)·0 citations
6. 06*

   $S$-factor and scattering parameters from ${}^3$He + ${}^4$He $\to {}^7$Be + $\gamma$ data

   Xilin Zhang🇺🇸 · Kenneth M. Nollett · Daniel R. Phillips🇺🇸

   We use the next-to-leading-order (NLO) amplitude in an effective field theory (EFT) for ${}^3$He + ${}^4$He $\to {}^7$Be + $\gamma$ to perform the extrapolation of higher-energy data to solar energies. At this order the EFT describes the capture process using an s-wave scattering length and effective range, the asymptotic behavior of ${}^7$Be and its excited state, and short-distance contributions to the E1 capture amplitude. We use a Bayesian analysis to infer the multi-dimensional posterior of these parameters from capture data below 2 MeV. The total $S$-factor $S(0)=0.578_{-0.016}^{+0.015}$ keV b at 68% degree of belief. We also find significant constraints on ${}^3$He-${}^4$He scattering parameters.

   ↳ nucl-thnucl-exSpringer Proc.Phys.(2020)·6 citations
7. 07*

   Deep-inelastic and quasielastic electron scattering from $A=3$ nuclei

   A. J. Tropiano🇺🇸 · J. J. Ethier🇳🇱 · W. Melnitchouk🇺🇸 · N. Sato🇺🇸

   We perform a combined analysis of inclusive electron scattering data from $A=3$ nuclei in the deep-inelastic and quasielastic scattering regions, using Monte Carlo analysis methods and the nuclear weak binding approximation to establish the range over which the data can be described within the same theoretical framework. Comparison with quasielastic ${}^3$He cross sections from SLAC and Jefferson Lab suggests that most features of the $x\gtrsim 1$ data can be reasonably well described in the impulse approximation with finite-$Q^2$ nuclear smearing functions for momentum transfers $Q^2\gtrsim 1$ GeV${}^2$. For the DIS region, we analyze the recent ${}^3$He to deuterium cross section ratio from the Jefferson Lab E03-103 experiment to explore the possible isospin dependence of the nuclear effects. We discuss the implications of this for the MARATHON experiment at Jefferson Lab, and outline how a Bayesian analysis of ${}^3$He, ${}^3$H and deuterium data can robustly determine the free neutron structure function.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2019)·19 citations
8. 08*

   Elucidating the multiplicity dependence of J/$\psi$ production in proton-proton collisions with PYTHIA8

   S. G. Weber🇩🇪 · A. Dubla🇩🇪 · A. Andronic🇩🇪 · A. Morsch🇨🇭

   A study of prompt and non-prompt J/$\psi$ production as a function of charged-particle multiplicity in inelastic proton--proton (pp) collisions at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV based on calculations using the PYTHIA8 Monte Carlo is reported. Recent experimental data shows an intriguing stronger-than-linear increase of the self-normalized J/$\psi$ yield with multiplicity; several models, based on initial or final state effects, have been able to describe the observed behaviour. In this paper, the microscopic reasons for this behaviour, like the role of multiple parton interactions, colour reconnections and auto-correlations are investigated. It is observed that the stronger-than-linear increase and the transverse momentum ($p_{\mathrm{T}}$) dependence, contrary to what is predicted by the other available models, can be attributed to auto-correlation effects only. In absence of auto-correlation effects, the increase of the yield of J/$\psi$ with multiplicity -- and in general for all hard processes -- is weaker than linear for multiplicities exceeding about three times the mean multiplicity. The possibility of disentangling auto-correlation effects from other physical phenomena by measuring the charged-particle multiplicity in different pseudo-rapidity and azimuthal regions relative to the J/$\psi$ direction is investigated. In this regard, it is suggested to extend the experimental measurements of J/$\psi$ production as a function of the charged-particle multiplicity by determining the multiplicity in several azimuthal regions and in particular in the Transverse region with respect to the direction of the J/$\psi$ meson.

   ↳ nucl-thhep-phnucl-exEPJC(2019)·61 citations
9. 09*

   The QCD Phase Diagram from Statistical Model Analysis

   Reinhard Stock🇩🇪 · Francesco Becattini🇮🇹 · Marcus Bleicher🇩🇪 · Jan Steinheimer🇩🇪

   In high multiplicity nucleus-nucleus collisions baryon-antibaryon annihilation and regeneration occur during the final hadronic expansion phase, thus distorting the initial equilibrium multiplicity ratios. We quantify the modifications employing the hybrid UrQMD transport model and apply them to the grand canonical partition functions of the Statistical Hadronization Model(SHM). We analyze minimum bias and central Pb+Pb collision data at SPS and LHC energy. We explain the Pion to Proton ratio puzzle. We also reproduce the deuteron to proton ratio at LHC energy by the SHM, and by UrQMD after attaching a phase space coalescence process. We discuss the resulting (T,${\mu }_B$) diagram.

   ↳ nucl-thnucl-exNPA(2019)·9 citations
10. 10*

    Three-loop formula for quark and gluon contributions to the QCD trace anomaly

    Kazuhiro Tanaka (Juntendo Univ.)🇯🇵

    In the QCD energy-momentum tensor $T^{\mu \nu }$, the terms that contribute to physical matrix elements are expressed as the sum of the gauge-invariant quark part and gluon part. Each part undergoes the renormalization due to the interactions among quarks and gluons, although the total tensor $T^{\mu \nu }$ is not renormalized thanks to the conservation of energy and momentum. Recently it has been shown that, through the renormalization, each of the quark and gluon parts of $T^{\mu \nu }$ receives a definite amount of anomalous trace contribution, such that their sum reproduces the well-known QCD trace anomaly, $T_{\mu }^{\mu }=(\beta /2g)F^{\mu \nu }{F}_{\mu \nu }+m(1+{\gamma }_m)\bar{\psi }\psi$, and the corresponding formulas have been derived up to two-loop order. We extend this result to the three-loop order, working out all the relevant three-loop renormalization structure for the quark and gluon energy-momentum tensors in the (modified) minimal subtraction scheme in the dimensional regularization. We apply our three-loop formula of the quark/gluon decomposition of the trace anomaly to calculate the anomaly-induced mass structure of nucleons as well as pions.

    ↳ hep-phhep-exnucl-exnucl-thJHEP(2019)·49 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.