Tue·Oct 1, 2019Tuesday·October 1, 2019

1. 01*

   A new description of transverse momentum spectra of identified particles produced in proton-proton collisions at high energies

   Pei-Pin Yang🇨🇳 · Fu-Hu Liu🇨🇳 · Raghunath Sahoo🇮🇳

   The transverse momentum spectra of identified particles produced in high energy proton-proton ($p+p$) collisions are empirically described by a new method with the framework of participant quark model or the multisource model at the quark level, in which the source itself is exactly the participant quark. Each participant (constituent) quark contributes to the transverse momentum spectrum, which is described by the TP-like function, a revised Tsallis--Pareto-type function. The transverse momentum spectrum of the hadron is the convolution of two or more TP-like functions. For a lepton, the transverse momentum spectrum is the convolution of two TP-like functions due to two participant quarks, e.g. projectile and target quarks, taking part in the collisions. A discussed theoretical approach seems to describe the $p+p$ collisions data at center-of-mass energy $\sqrt{s}=200$ GeV, 2.76 TeV, and 13 TeV very well.

   ↳ hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2020)·12 citations
2. 02*

   Glauber model for small system using anisotropic and inhomogeneous density profile of proton

   Suman Deb🇮🇳 · Golam Sarwar🇮🇳 · Dhananjaya Thakur🇮🇳 · Pavish S. · Raghunath Sahoo🇮🇳 · Jan-e Alam🇮🇳

   Recent studies reveal that at high energies, collisions of small system like $p+p$ gives signatures similar to that widely observed in heavy ion collisions hinting towards a possibility of forming a medium with collective behaviour. With this motivation, we have used the Glauber model, which is traditionally applied to heavy ion collisions, in small system using anisotropic and inhomogeneous density profile of proton and found that the proposed model reproduces the charged particle multiplicity distribution of $p+p$ collisions at LHC energies very well. Collision geometric properties like mean impact parameter, mean number of binary collisions ($⟨N_{coll}⟩$) and mean number of participants ($⟨N_{part}⟩$) at different multiplicities are determined. Having estimated $⟨N_{coll}⟩$, we have calculated nuclear modification-like factor ($R_{HL}$) in $p+p$ collisions. We also estimated eccentricity and elliptic flow as a function of charged particle multiplicity using the linear response to initial geometry.

   ↳ hep-phnucl-exnucl-thPRD(2020)·10 citations
3. 03*

   Long-distance Contributions to Neutrinoless Double Beta Decay ${\pi }^{-}\to {\pi }^{+}ee$

   Xin-Yu Tuo🇨🇳 · Xu Feng🇨🇳 · Lu-Chang Jin🇺🇸

   Neutrinoless double beta decay, if detected, would prove that neutrinos are Majorana fermions and provide the direct evidence for lepton number violation. If such decay would exist in nature, then ${\pi }^{-}{\pi }^{-}\to ee$ and ${\pi }^{-}\to {\pi }^{+}ee$ (or equivalently ${\pi }^{-}{e}^{+}\to {\pi }^{+}{e}^{-}$) are the two simplest processes accessible via first-principle lattice QCD calculations. In this work, we calculate the long-distance contributions to the ${\pi }^{-}\to {\pi }^{+}ee$ transition amplitude using four ensembles at the physical pion mass with various volumes and lattice spacings. We adopt the infinite-volume reconstruction method to control the finite-volume effects arising from the (almost) massless neutrino. Providing the lattice QCD inputs for chiral perturbation theory, we obtain the low energy constant $g_{\nu }^{\pi \pi }(m_{\rho })=-10.89(28{)}_{\text{stat}}(74{)}_{\text{sys}}$, which is close to $g_{\nu }^{\pi \pi }(m_{\rho })=-11.96(31{)}_{\text{stat}}$ determined from the crossed-channel ${\pi }^{-}{\pi }^{-}\to ee$ decay.

   ↳ hep-lathep-phnucl-exnucl-thPRD(2019)·56 citations
4. 04*

   Ion detector for Accelerator Mass Spectrometry based on low-pressure TPC with THGEM readout

   A. Bondar🇷🇺 · A. Buzulutskov · E. Frolov · V. Parkhomchuk · A. Petrozhitskiy · T. Shakirova · A. Sokolov🇷🇺

   A new technique for ion identification in Accelerator Mass Spectrometry (AMS) has been proposed by measuring the ion track ranges using a low-pressure TPC. As a proof of principle, a low-pressure TPC with charge readout using a THGEM multiplier was developed. The tracks of alpha particles from various radioactive sources were successfully recorded in the TPC. The track ranges were measured with a high accuracy, reaching the 2% resolution level. Using these results and the SRIM code simulation, it is shown that the isobaric boron and beryllium ions can be effectively separated at ten sigma level. It is expected that this technique will be applied in the AMS facility in Novosibirsk for dating geological objects, in particular for the geochronology of Cenozoic Era.

   ↳ physics.ins-detnucl-exJINST(2020)·2 citations
5. 05*

   Effects of curvature of the symmetry energy in Sn+Sn reactions at 270 MeV/nucleon

   Ya-Fei Guo🇨🇳 · Gao-Chan Yong🇨🇳

   Based on the Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, the isotope Sn+Sn reactions at 270 MeV/nucleon are investigated. It is shown that nucleon and meson observables in the Sn+Sn reactions at 270 MeV/nucleon cannot effectively probe the high-density symmetry energy. These observables, however, are sensitive to the curvature of the symmetry energy. It thus sheds light on the study of the high-density behavior of the nuclear symmetry energy by extracting the curvature of the symmetry energy through the interpretation of forthcoming RIBF/RIKEN related data.

   ↳ nucl-thnucl-ex2 citations
6. 06*

   Form factors for the Nucleon-to-Roper electromagnetic transition at large-$Q^2$

   José Rodríguez-Quintero🇪🇸 · Daniele Binosi🇮🇹 · Chen Chen🇩🇪 · Ya Lu🇨🇳 · Craig D. Roberts🇨🇳 · Jorge Segovia🇪🇸

   We report on a recent calculation of all Roper-related electromagnetic transtions form factors, covering the range of energies that next-to-come planned experiments are expected to map. Direct reliable calculations were performed, within a Poincaré covariant approach of the three-body bound-state problem, up to $Q^2/m_N^2$=6; approximated then by applying the Schlessinger point method and the results eventually extended up to $Q^2/m_N^2\simeq$12 via analytic continuation.

   ↳ nucl-thhep-phnucl-exEPJ Web Conf.(2020)·8 citations
7. 07*

   Process-independent effective coupling and the pion structure function

   José Rodríguez-Quintero🇪🇸 · Lei Chang🇨🇳 · Khépani Raya🇨🇳 · Craig D. Roberts🇨🇳

   We sketch the calculation of the pion structure functions within the DSE framework, following two alternative albeit consistent approaches, and discuss then their QCD evolution, the running driven by an effective charge, from a hadronic scale up to any larger one accessible to experiment.

   ↳ hep-phnucl-exnucl-thJ.Phys.Conf.Ser.(2020)·9 citations
8. 08*

   Unified Description of Polarized and Unpolarized Quark Distributions in the Proton

   Tianbo Liu🇺🇸 · Raza Sabbir Sufian🇺🇸 · Guy F. de Téramond🇨🇷 · Hans Günter Dosch🇩🇪 · Stanley J. Brodsky🇺🇸 · Alexandre Deur🇺🇸

   We propose a unified new approach to describe polarized and unpolarized quark distributions in the proton based on the gauge-gravity correspondence, light-front holography, and the generalized Veneziano model. We find that the spin-dependent quark distributions are uniquely determined in terms of the unpolarized distributions by chirality separation without the introduction of additional free parameters. The predictions are consistent with existing experimental data and agree with perturbative QCD constraints at large longitudinal momentum $x$. In particular, we predict the sign reversal of the polarized down-quark distribution in the proton at $x=0.8\pm 0.03$, a key property of nucleon substructure which will be tested very soon in upcoming experiments.

   ↳ hep-phhep-exnucl-exnucl-thPRL(2020)·43 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.