Fri·Jan 8, 2021Friday·January 8, 2021

1. 01*

   Shape changes in the mirror nuclei ${}^{70}$Kr and ${}^{70}$Se

   K. Wimmer🇯🇵 · W. Korten🇫🇷 · P. Doornenbal🇯🇵 · T. Arici🇩🇪 · P. Aguilera🇨🇱 · A. Algora🇪🇸 · T. Ando🇯🇵 · H. Baba🇯🇵 · B. Blank🇫🇷 · A. Boso🇮🇹 · S. Chen🇯🇵 · A. Corsi🇫🇷 and 26 other authors

   We studied the proton-rich $T_z=-1$ nucleus ${}^{70}$Kr through inelastic scattering at intermediate energies in order to extract the reduced transition probability, $B(E2;0^{+}\to 2^{+})$. Comparison with the other members of the $A=70$ isospin triplet, ${}^{70}$Br and ${}^{70}$Se, studied in the same experiment, shows a $3\sigma$ deviation from the expected linearity of the electromagnetic matrix elements as a function of $T_z$. At present, no established nuclear structure theory can describe this observed deviation quantitatively. This is the first violation of isospin symmetry at this level observed in the transition matrix elements. A heuristic approach may explain the anomaly by a shape change between the mirror nuclei ${}^{70}$Kr and ${}^{70}$Se contrary to the model predictions.

   nucl-exnucl-thPRL(2021)·38 citations
2. 02*

   Multi-harmonic correlations of different flow amplitudes in Pb-Pb collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=2.76$ TeV

   ALICE Collaboration

   The event-by-event correlations between three flow amplitudes are measured for the first time in Pb--Pb collisions, using higher-order Symmetric Cumulants. We find that different three-harmonic correlations develop during the collective evolution of the medium, when compared with correlations that exist in the initial state. These new results cannot be interpreted in terms of previous lower-order flow measurements, since contributions from two-harmonic correlations are explicitly removed in the new observables. Comparison with Monte Carlo simulations provides new and independent constraints for the initial conditions and system properties of nuclear matter created in heavy-ion collisions.

   nucl-exhep-exPRL(2021)·25 citations
3. 03*

   First measurement of coherent ${\rho }^0$ photoproduction in ultra-peripheral Xe-Xe collisions at $\sqrt{{\mathbf{s}}_{\mathbf{NN}}}=5.44$ TeV

   ALICE Collaboration

   The first measurement of the coherent photoproduction of ${\rho }^0$ vector mesons in ultra-peripheral Xe-Xe collisions at $\sqrt{s_{\mathrm{NN}}}=5.44$ TeV is presented. This result, together with previous HERA $\gamma$p data and $\gamma$-Pb measurements from ALICE, describes the atomic number ($A$) dependence of this process, which is particularly sensitive to nuclear shadowing effects and to the approach to the black-disc limit of QCD at a semi-hard scale. The cross section of the $\mathrm{Xe}+\mathrm{Xe}\to {\rho }^0+\mathrm{Xe}+\mathrm{Xe}$ process, measured at midrapidity through the decay channel ${\rho }^0\to {\pi }^{+}{\pi }^{-}$, is found to be $\mathrm{d}\sigma /\mathrm{d}y=131.5\pm 5.6{(stat.)}_{-16.9}^{+17.5}(syst.)$ mb. The ratio of the continuum to resonant contributions for the production of pion pairs is also measured. In addition, the fraction of events accompanied by electromagnetic dissociation of either one or both colliding nuclei is reported. The dependence on $A$ of cross section for the coherent ${\rho }^0$ photoproduction at a centre-of-mass energy per nucleon of the $\gamma A$ system of $W_{\gamma A,n}=65$ GeV is found to be consistent with a power-law behaviour $\sigma (\gamma A\to {\rho }^{0}A)\propto A^{\alpha }$ with a slope $\alpha =0.96\pm 0.02(syst.)$. This slope signals important shadowing effects, but it is still far from the behaviour expected in the black-disc limit.

   nucl-exhep-exPLB(2021)·55 citations
4. 04*

   Net-baryon number fluctuations

   C. Schmidt🇩🇪 · J. Goswami🇩🇪 · G. Nicotra🇩🇪 · F. Ziesché🇩🇪 · P. Dimopoulos🇮🇹 · F. Di Renzo🇮🇹 · S. Singh🇮🇹 · K. Zambello🇮🇹

   The appearance of large, none-Gaussian cumulants of the baryon number distribution is commonly discussed as a signal for the QCD critical point. We review the status of the Taylor expansion of cumulant ratios of baryon number fluctuations along the freeze-out line and also compare QCD results with the corresponding proton number fluctuations as measured by the STAR Collaboration at RHIC. To further constrain the location of a possible QCD critical point we discuss poles of the baryon number fluctuations in the complex plane. Here we use not only the Taylor coefficients obtained at zero chemical potential but perform also calculations of Taylor expansion coefficients of the pressure at purely imaginary chemical potentials.

   ↳ hep-lathep-phnucl-exnucl-thActa Phys. Pol. B Proc. Suppl. 14, 241 (2…·19 citations
5. 05*

   A novel approach for nearly-coincident events rejection

   M. Borghesi🇮🇹 · M. De Gerone🇮🇹 · M. Faverzani🇮🇹 · M. Fedkevych🇩🇪 · E. Ferri🇮🇹 · G. Gallucci🇮🇹 · A. Giachero🇮🇹 · A. Nucciotti🇮🇹 · A. Puiu🇮🇹

   We present a novel technique, called DSVP (Discrimination through Singular Vectors Projections), to discriminate spurious events within a dataset. The purpose of this paper is to lay down a general procedure which can be tailored for a broad variety of applications. After describing the general concept, we apply the algorithm to the problem of identifying nearly coincident events in low temperature microcalorimeters in order to push the time resolution close to its intrinsic limit. In fact, from simulated datasets it was possible to achieve an effective time resolution even shorter than the sampling time of the system considered. The obtained results are contextualized in the framework of the HOLMES experiment, which aims at directly measuring the neutrino mass with the calorimetric approach, allowing to significally improve its statistical sensitivity.

   ↳ physics.ins-detnucl-exEPJC(2021)·10 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.