Fri·Dec 21, 2018Friday·December 21, 2018

1. 01*

   Using Nab to determine correlations in unpolarized neutron decay

   L. J. Broussard🇺🇸 · S. Baeßler🇺🇸 · T. L. Bailey🇺🇸 · N. Birge🇺🇸 · J. D. Bowman🇺🇸 · C. B. Crawford🇺🇸 · C. Cude-Woods🇺🇸 · D. E. Fellers🇺🇸 · N. Fomin🇺🇸 · E. Frlež🇺🇸 · M. T. W. Gericke🇨🇦 · L. Hayen🇧🇪 and 19 other authors

   The Nab experiment will measure the ratio of the weak axial-vector and vector coupling constants $\lambda =g_A/g_V$ with precision $\delta \lambda /\lambda \sim 3\times 10^{-4}$ and search for a Fierz term $b_F$ at a level $\Delta b_F<10^{-3}$. The Nab detection system uses thick, large area, segmented silicon detectors to very precisely determine the decay proton's time of flight and the decay electron's energy in coincidence and reconstruct the correlation between the antineutrino and electron momenta. Excellent understanding of systematic effects affecting timing and energy reconstruction using this detection system are required. To explore these effects, a series of ex situ studies have been undertaken, including a search for a Fierz term at a less sensitive level of $\Delta b_F<10^{-2}$ in the beta decay of ${}^{45}$Ca using the UCNA spectrometer.

   nucl-exphysics.ins-detHyperfine Interact.(2019)·30 citations
2. 02*

   Slow neutron production as a probe of hadron formation in high-energy ${\gamma }^{\ast }A$ reactions

   A.B. Larionov🇩🇪 · M. Strikman🇺🇸

   Deep Inelastic Scattering (DIS) experiments at the planned Electron-Ion Collider will be affected by details of the hadron formation inside the nuclear volume. Besides semi-inclusive particle production experiments decays of the target nucleus via emission of neutrons provide an additional opportunity to probe this domain. This paper reports on the hybrid dynamical+statistical calculations of low-energy neutron production in muon- and virtual photon-induced collisions with nuclei. We confirm the conclusion that the E665 data on neutron production in ${\mu }^{-}$ + Pb DIS at 470 GeV indicate a strong suppression of the final state interaction for hadrons with momenta above $\sim 1$ GeV/c. Ultraperipheral heavy-ion collisions at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) can be used to test this suppression. The calculations of the neutron multiplicity distributions and $p_t$-spectra in photon - nucleus collisions at the energies accessible at the LHC and RHIC are presented for several models of hadron formation. We argue that studies of neutron production in ultraperipheral heavy ion collisions open a new window on the small-$x$ dynamics and hadron component of the photon wave function.

   ↳ hep-phhep-exnucl-exnucl-thPRC(2020)·13 citations
3. 03*

   Chiral crossover in QCD at zero and non-zero chemical potentials

   A. Bazavov🇺🇸 · H.-T. Ding🇨🇳 · P. Hegde🇮🇳 · O. Kaczmarek🇩🇪 · F. Karsch🇩🇪 · N. Karthik🇺🇸 · E. Laermann🇩🇪 · Anirban Lahiri🇩🇪 · R. Larsen🇺🇸 · S.-T. Li🇨🇳 · Swagato Mukherjee🇺🇸 · H. Ohno🇯🇵 and 5 other authors

   We present results for pseudo-critical temperatures of QCD chiral crossovers at zero and non-zero values of baryon ($B$), strangeness ($S$), electric charge ($Q$), and isospin ($I$) chemical potentials ${\mu }_{X=B,Q,S,I}$. The results were obtained using lattice QCD calculations carried out with two degenerate up and down dynamical quarks and a dynamical strange quark, with quark masses corresponding to physical values of pion and kaon masses in the continuum limit. By parameterizing pseudo-critical temperatures as $T_c({\mu }_X)=T_c(0)\left[1-{\kappa }_2^X({\mu }_X/T_c(0){)}^2-{\kappa }_4^X({\mu }_X/T_c(0){)}^4\right]$, we determined ${\kappa }_2^X$ and ${\kappa }_4^X$ from Taylor expansions of chiral observables in ${\mu }_X$. We obtained a precise result for $T_c(0)=(156.5\pm 1.5)\mathrm{MeV}$. For analogous thermal conditions at the chemical freeze-out of relativistic heavy-ion collisions, i.e., ${\mu }_S(T,{\mu }_B)$ and ${\mu }_Q(T,{\mu }_B)$ fixed from strangeness-neutrality and isospin-imbalance, we found ${\kappa }_2^B=0.012(4)$ and ${\kappa }_4^B=0.000(4)$. For ${\mu }_B\lesssim 300\mathrm{MeV}$, the chemical freeze-out takes place in the vicinity of the QCD phase boundary, which coincides with the lines of constant energy density of $0.42(6){GeV/fm}^3$ and constant entropy density of $3.7(5){\mathrm{fm}}^{-3}$.

   ↳ hep-lathep-phhep-thnucl-ex+1PLB(2019)·878 citations
4. 04*

   Elastic differential cross-section measurement at $\sqrt{s}=13$ TeV by TOTEM

   TOTEM Collaboration: G. Antchev🇧🇬 · P. Aspell🇨🇭 · I. Atanassov🇧🇬 · V. Avati🇵🇱 · J. Baechler🇨🇭 · C. Baldenegro Barrera🇺🇸 · V. Berardi🇮🇹 · M. Berretti🇫🇮 · E. Bossini🇮🇹 · U. Bottigli🇮🇹 · M. Bozzo🇮🇹 · H. Burkhardt🇨🇭 and 64 other authors

   The TOTEM collaboration has measured the elastic proton-proton differential cross section $\mathrm{d}\sigma /\mathrm{d}t$ at $\sqrt{s}=13$ TeV LHC energy using dedicated ${\beta }^{\ast }=90$ m beam optics. The Roman Pot detectors were inserted to 10$\sigma$ distance from the LHC beam, which allowed the measurement of the range $[0.04$ GeV${}^2$$;4$GeV${}^2$$]$ in four-momentum transfer squared $|t|$. The efficient data acquisition allowed to collect about 10${}^9$ elastic events to precisely measure the differential cross-section including the diffractive minimum (dip), the subsequent maximum (bump) and the large-$|t|$ tail. The average nuclear slope has been found to be $B=(20.40\pm 0.002^{\mathrm{stat}}\pm 0.01^{\mathrm{syst}})$GeV${}^{-2}$ in the $|t|$-range $0.04$GeV${}^2$ to $0.2$GeV${}^2$. The dip position is $|t_{\mathrm{dip}}|=(0.47\pm 0.004^{\mathrm{stat}}\pm 0.01^{\mathrm{syst}})$GeV${}^2$. The differential cross section ratio at the bump vs. at the dip $R=1.77\pm 0.01^{\mathrm{stat}}$ has been measured with high precision. The series of TOTEM elastic pp measurements show that the dip is a permanent feature of the pp differential cross-section at the TeV scale.

   ↳ hep-exhep-phnucl-exEPJC(2019)·130 citations
5. 05*

   Low-lying dipole strengths for probable $p$-wave one-neutron halos in the medium mass region

   Manju (IITR) · J. Singh (Uni Hokkaido)🇯🇵 · Shubhchintak (ULB)🇺🇸 · R. Chatterjee (IITR)🇮🇳

   The one-neutron halos lying in the island of inversion around $N=20$ has provided the podium, to study the variation of total low-lying dipole strength with the neutron separation energy. We study three probable p-wave one-neutron halo candidates 31Ne and 34Na and 37Mg lying in the island of inversion. A simple analytic model has been used for the calculation of the total low-lying dipole strength for the medium mass p-wave one-neutron halos. A correction factor to this analytical model has been estimated with a realistic Woods-Saxon potential. A comparison of these analytic calculations has been made with the those performed by a finite-range distorted-wave Born approximation theory of the Coulomb dissociation. We also make an estimate of the one-neutron separation energies of 31Ne, 34Na and 37Mg.

   ↳ nucl-thnucl-exEPJA(2019)·14 citations
6. 06*

   Elastic differential cross-section $\mathrm{d}\sigma /\mathrm{d}t$ at $\sqrt{s}=$2.76 TeV and implications on the existence of a colourless 3-gluon bound state

   TOTEM Collaboration: G. Antchev🇧🇬 · P. Aspell🇨🇭 · I. Atanassov🇧🇬 · V. Avati🇵🇱 · J. Baechler🇨🇭 · C. Baldenegro Barrera🇺🇸 · V. Berardi🇮🇹 · M. Berretti🇫🇮 · E. Bossini🇮🇹 · U. Bottigli🇮🇹 · M. Bozzo🇮🇹 · H. Burkhardt🇨🇭 and 63 other authors

   The proton-proton elastic differential cross section $\mathrm{d}\sigma /\mathrm{d}t$ has been measured by the TOTEM experiment at $\sqrt{s}=2.76$ TeV energy with ${\beta }^{\ast }=11$ m beam optics. The Roman Pots were inserted to 13 times the transverse beam size from the beam, which allowed to measure the differential cross-section of elastic scattering in a range of the squared four-momentum transfer ($|t|$) from $0.36$ GeV${}^2$ to $0.74$ GeV${}^2$. The differential cross-section can be described with an exponential in the $|t|$-range between $0.36$ GeV${}^2$ and $0.54$ GeV${}^2$, followed by a diffractive minimum (dip) at $|t_{\mathrm{dip}}|=0.61\pm 0.03$ GeV${}^2$ and a subsequent maximum (bump). The ratio of the $\mathrm{d}\sigma /\mathrm{d}t$ at the bump and at the dip is $1.7\pm 0.2$. When compared to the $\mathrm{p}\bar{\mathrm{p}}$ measurement of the D0 experiment at $\sqrt{s}=1.96$ TeV, a significant difference can be observed. Under the condition that the effects due to the energy difference between TOTEM and D0 can be neglected, the result provides evidence for a colourless 3-gluon bound state exchange in the $t$-channel of the proton-proton elastic scattering.

   ↳ hep-exhep-phnucl-exEPJC(2020)·122 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.