Tue·Oct 24, 2017Tuesday·October 24, 2017

1. 01*

   Searching for neutrinoless double beta decay with GERDA

   GERDA Collaboration: M. Agostini🇩🇪 · A.M. Bakalyarov🇷🇺 · M. Balata🇮🇹 · I. Barabanov🇷🇺 · L. Baudis🇨🇭 · C. Bauer🇩🇪 · E. Bellotti🇮🇹 · S. Belogurov🇷🇺 · A. Bettini🇮🇹 · L. Bezrukov🇷🇺 · T. Bode🇩🇪 · V. Brudanin🇷🇺 and 93 other authors

   The GERmanium Detector Array (GERDA) experiment located at the INFN Gran Sasso Laboratory (Italy), is looking for the neutrinoless double beta decay of Ge76, by using high-purity germanium detectors made from isotopically enriched material. The combination of the novel experimental design, the careful material selection for radio-purity and the active/passive shielding techniques result in a very low residual background at the Q-value of the decay, about 1e-3 counts/(keV kg yr). This makes GERDA the first experiment in the field to be background-free for the complete design exposure of 100 kg yr. A search for neutrinoless double beta decay was performed with a total exposure of 47.7 kg yr: 23.2 kg yr come from the second phase (Phase II) of the experiment, in which the background is reduced by about a factor of ten with respect to the previous phase. The analysis presented in this paper includes 12.4 kg yr of new Phase II data. No evidence for a possible signal is found: the lower limit for the half-life of Ge76 is 8.0e25 yr at 90% CL. The experimental median sensitivity is 5.8e25 yr. The experiment is currently taking data. As it is running in a background-free regime, its sensitivity grows linearly with exposure and it is expected to surpass 1e26 yr within 2018.

   nucl-exphysics.ins-detJ.Phys.Conf.Ser.(2020)·20 citations
2. 02*

   Pseudorapidity and transverse momentum dependence of flow harmonics in pPb and PbPb collisions

   CMS Collaboration

   Measurements of azimuthal angular correlations are presented for high-multiplicity pPb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV and peripheral PbPb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 2.76 TeV. The data used in this work were collected with the CMS detector at the CERN LHC. Fourier coefficients as functions of transverse momentum and pseudorapidity are studied using the scalar product method, 4-, 6-, and 8-particle cumulants, and the Lee-Yang zeros technique. The influence of event plane decorrelation is evaluated using the scalar product method and found to account for most of the observed pseudorapidity dependence.

   nucl-exhep-exPRC(2018)·50 citations
3. 03*

   Longitudinal asymmetry and its effect on pseudorapidity distributions in Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV

   ALICE Collaboration

   First results on the longitudinal asymmetry and its effect on the pseudorapidity distributions in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV at the Large Hadron Collider are obtained with the ALICE detector. The longitudinal asymmetry arises because of an unequal number of participating nucleons from the two colliding nuclei, and is estimated for each event by measuring the energy in the forward neutron-Zero-Degree-Calorimeters (ZNs). The effect of the longitudinal asymmetry is measured on the pseudorapidity distributions of charged particles in the regions $|\eta |<0.9$, $2.8<\eta <5.1$ and $-3.7<\eta <-1.7$ by taking the ratio of the pseudorapidity distributions from events corresponding to different regions of asymmetry. The coefficients of a polynomial fit to the ratio characterise the effect of the asymmetry. A Monte Carlo simulation using a Glauber model for the colliding nuclei is tuned to reproduce the spectrum in the ZNs and provides a relation between the measurable longitudinal asymmetry and the shift in the rapidity ($y_0$) of the participant zone formed by the unequal number of participating nucleons. The dependence of the coefficient of the linear term in the polynomial expansion, $c_1$, on the mean value of $y_0$ is investigated.

   nucl-exPLB(2018)·9 citations
4. 04*

   First Results from CUORE: A Search for Lepton Number Violation via $0\nu \beta \beta$ Decay of ${}^{130}$Te

   CUORE Collaboration: C. Alduino🇺🇸 · K. Alfonso🇺🇸 · E. Andreotti🇮🇹 · C. Arnaboldi🇮🇹 · F. T. Avignone III🇺🇸 · O. Azzolini🇮🇹 · I. Bandac🇺🇸 · T. I. Banks🇺🇸 · G. Bari🇮🇹 · M. Barucci🇮🇹 · J.W. Beeman🇺🇸 · F. Bellini🇮🇹 and 152 other authors

   The CUORE experiment, a ton-scale cryogenic bolometer array, recently began operation at the Laboratori Nazionali del Gran Sasso in Italy. The array represents a significant advancement in this technology, and in this work we apply it for the first time to a high-sensitivity search for a lepton-number--violating process: ${}^{130}$Te neutrinoless double-beta decay. Examining a total TeO${}_2$ exposure of 86.3 kg$\cdot$yr, characterized by an effective energy resolution of (7.7 $\pm$ 0.5) keV FWHM and a background in the region of interest of (0.014 $\pm$ 0.002) counts/(keV$\cdot$kg$\cdot$yr), we find no evidence for neutrinoless double-beta decay. The median statistical sensitivity of this search is $7.0\times 10^{24}$ yr. Including systematic uncertainties, we place a lower limit on the decay half-life of $T_{1/2}^{0\nu }$(${}^{130}$Te) > $1.3\times 10^{25}$ yr (90% C.L.). Combining this result with those of two earlier experiments, Cuoricino and CUORE-0, we find $T_{1/2}^{0\nu }$(${}^{130}$Te) > $1.5\times 10^{25}$ yr (90% C.L.), which is the most stringent limit to date on this decay. Interpreting this result as a limit on the effective Majorana neutrino mass, we find $m_{\beta \beta }<(110-520)$ meV, where the range reflects the nuclear matrix element estimates employed.

   nucl-exhep-exphysics.ins-detPRL(2018)·393 citations
5. 05*

   Beta decays in investigations and searches for rare effects

   V.I. Tretyak🇺🇦

   Current status of experimental investigations of rare single beta decays (48Ca, 50V, 96Zr, 113Cd, 113mCd, 115In, 123Te, 180mTa, 222Rn) is reviewed. Nuclei which decay through single beta decay very often constitute backgrounds in studies of rare effects like double beta decay, solar neutrinos or dark matter. Summary of correction factors used in description of forbidden beta decays is also briefly given.

   nucl-exastro-ph.IMnucl-thAIP Conf.Proc.(2017)·3 citations
6. 06*

   The collective behavior of the partons and its influence on the jet suppression in heavy ion collisions

   M.K. Suleymanov (COMSATS University Islamabad, Pakistan)🇵🇰

   We discuss the physical picture that a parton interaction with a coherent group of partons can lead to more jet quenching effect in the hot and dense matter created by heavy ion collisions at RHIC and LHC energies. We came to this picture after analyzing the behaviour of the nuclear modification factor as a function of $p_T$ for the charged particles produced in the most central Pb-Pb collisions at 2.76 A TeV. In the interval, $7-50GeV/c$ the values of the factor as a function of $p_T$ increases almost linearly with a slope is very close to expected one for the inverse Compton effect. Around $p_T\simeq 60$ GeV/c, a regime change occurs, which is characteristic for the phenomenon. We propose that this similarity can be explained by the inverse Compton effect for partons, which occurs via a collective parton group formation ( through the appearance of a new string as a result of the fusion of strings) and its interactions with single partons in the interval of $5<p_T<10GeV/c$. In the case of a coherent collision with a parton that has a lower energy than the group, the parton can gain energy through the inverse Compton effect, resulting in its acceleration and shifting to the region of $p_T>10$ GeV/c. After losing a significant part of its energy new string will decay into partons with lower energies - slowed partons in the interval of $p_T<5GeV/c$. This enhancement in the jet quenching can be observed in the interval of $2<p_T<20GeV/c$.

   nucl-ex2 citations
7. 07*

   Search for nucleon decays with EXO-200

   J.B. Albert · G. Anton · I. Badhrees · P.S. Barbeau · R. Bayerlein · D. Beck · V. Belov · M. Breidenbach · T. Brunner · G.F. Cao · W.R. Cen · C. Chambers and 83 other authors

   A search for instability of nucleons bound in ${}^{136}$Xe nuclei is reported with 223 kg$\cdot$yr exposure of ${}^{136}$Xe in the EXO-200 experiment. Lifetime limits of 3.3$\times 10^{23}$ and 1.9$\times 10^{23}$ yrs are established for nucleon decay to ${}^{133}$Sb and ${}^{133}$Te, respectively. These are the most stringent to date, exceeding the prior decay limits by a factor of 9 and 7, respectively.

   ↳ hep-exnucl-exphysics.ins-detPRD(2018)·23 citations
8. 08*

   Direct photon spectrum and elliptic flow produced from Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV at the CERN Large Hadron Collider within an integrated hydrokinetic model

   V.Yu. Naboka🇺🇦 · Yu.M. Sinyukov🇺🇦 · G.M. Zinovjev🇺🇦

   The photon transverse momentum spectrum and its anisotropy from Pb+Pb collisions at the CERN Large Hadron Collider energy $\sqrt{s_{NN}}=2.76$ TeV are investigated within the integrated hydrokinetic model (iHKM). Photon production is accumulated from the different processes at the various stages of relativistic heavy ion collisions: from the primary hard photons of very early stage of parton collisions to the thermal photons from equilibrated quark-gluon and hadron gas stages. Along the way a hadronic medium evolution is treated in two distinct, in a sense opposite, approaches: chemically equilibrated and chemically frozen system expansion. Studying the centrality dependence of the results obtained allows us to conclude that a relatively strong transverse momentum anisotropy of thermal radiation is suppressed by prompt photon emission which is an isotropic. We find out that this effect is getting stronger as centrality increases because of the simultaneous increase in the relative contribution of prompt photons in the soft part of the spectra. The substantial results obtained in iHKM with nonzero viscosity ($\eta /s=0.08$) for photon spectra and $v_2$ coefficients are mostly within the error bars of experimental data, but there is some systematic underestimation of both observables for the near central events. We claim that a situation could be significantly improved if an additional photon radiation that accompanies the presence of a deconfined environment is included. Since a matter of a space-time layer where hadronization takes place is actively involved in anisotropic transverse flow, both positive contributions to the spectra and $v_2$ are considerable, albeit such an argument needs further research and elaboration.

   ↳ hep-phnucl-exnucl-thPRC(2018)·11 citations
9. 09*

   Ring like correlation in relativistic heavy ion collision: an experimental probe using continuous wavelet transform approach

   Gopa Bhoumik🇮🇳 · Argha Deb🇮🇳 · Swarnapratim Bhattacharyya🇮🇳 · Dipak Ghosh🇮🇳

   Continuous wavelet transform approach has been applied to the pseudo-rapidity distribution of shower particles produced in 16O-AgBr interactions at 60 AGeV and 32S-AgBr interactions at 200 AgeV. Multiscale analysis of wavelet pseudo-rapidity spectra has been performed in order to find out the presence of ring-like correlation, which could be either due to production of Cherenkov gluons or due to propagation of Mach Shock wave through excited nuclear matter. This approach fulfils the basic requirement of both effects that they lead to an overabundance of considered particles at some typical pseudo-rapidities. Comparison of experimental results with that obtained from analyzing events generated by FRITIOF code are not reproduced.

   ↳ hep-exnucl-exIJMPE(2019)·1 citation
10. 10*

    New results on heavy-flavour in heavy-ion collisions with LHCb

    Jiajia Qin🇨🇳

    Heavy-flavour quarks are important to probe Quark-Gluon Plasma(QGP) properties. Cold Nuclear Matter(CNM) effects can be accessed by $p$Pb collisions. LHCb is a heavy-flavour precision experiment and has collected large collision data samples. Production cross-section measurements of prompt $D^0$ at $\sqrt{s_{\mathrm{NN}}}$= 5 TeV and $J/\psi$ at $\sqrt{s_{\mathrm{NN}}}$= 8.16 TeV are presented.

    ↳ hep-exnucl-ex0 citations
11. 11*

    Phenomenological study of the pp -> pi+ pn reaction

    G.Faeldt🇸🇪 · C.Wilkin🇬🇧

    Fully constrained bubble chamber data on the pp -> pi+ pn and pp -> pi+ d reactions are used to investigate the ratio of the counting rates for the two processes as function of the pn excitation energy Q. Though it is important to include effects associated with the p-wave nature of pion production, the data are insufficient to establish unambiguously the dependence on Q. The angular distributions show the presence of higher partial waves which seem to be anomalously large at small Q. The dispersion relation method to determine scattering lengths is extended to encompass cases where, as for the pp -> pi+ pn reaction, there is a bound state and, in a test example, it is shown that the values deduced for the low energy neutron-proton scattering parameters are significantly influenced by the pion p-wave behavior.

    ↳ nucl-thnucl-exPRC(2018)·0 citations
12. 12*

    Role of deformation in odd-even staggering in reaction cross sections for ${}^{30,31,32}$Ne and ${}^{36,37,38}$Mg isotopes

    Y. Urata · K. Hagino · H. Sagawa🇯🇵

    We discuss the role of pairing anti-halo effect in the observed odd-even staggering in reaction cross sections for ${}^{30,31,32}$Ne and ${}^{36,37,38}$Mg isotopes by taking into account the ground state deformation of these nuclei. To this end, we construct the ground state density for the ${}^{30,31}$Ne and ${}^{36,37}$Mg nuclei based on a deformed Woods-Saxon potential, while for the ${}^{32}$Ne and ${}^{38}$Mg nuclei we also take into account the pairing correlation using the Hartree-Fock-Bogoliubov method. We demonstrate that, when the one-neutron separation energy is small for the odd-mass nuclei, a significant odd-even staggering still appears even with finite deformation, although the degree of staggering is somewhat reduced compared to the spherical case. This implies that the pairing anti-halo effect in general plays an important role in generating the odd-even staggering in reaction cross sections for weakly bound nuclei.

    ↳ nucl-thnucl-exPRC(2017)·21 citations
13. 13*

    Short range correlations and the isospin dependence of nuclear correlation functions

    Reynier Cruz-Torres🇺🇸 · Axel Schmidt🇺🇸 · Gerald A. Miller🇺🇸 · Lawrence B. Weinstein🇺🇸 · Nir Barnea🇮🇱 · Ronen Weiss🇮🇱 · Eliezer Piasetzky🇮🇱 · Or Hen🇺🇸

    Pair densities and associated correlation functions provide a critical tool for introducing many-body correlations into a wide-range of effective theories. Ab initio calculations show that two-nucleon pair-densities exhibit strong spin and isospin dependence. However, such calculations are not available for all nuclei of current interest. We therefore provide a simple model, which involves combining the short and long separation distance behavior using a single blending function, to accurately describe the two-nucleon correlations inherent in existing ab initio calculations. We show that the salient features of the correlation function arise from the features of the two-body short-range nuclear interaction, and that the suppression of the pp and nn pair-densities caused by the Pauli principle is important. Our procedure for obtaining pair-density functions and correlation functions can be applied to heavy nuclei which lack ab initio calculations.

    ↳ nucl-thnucl-exPLB(2018)·43 citations
14. 14*

    Enhancements of high order cumulants across the 1st order phase transition boundary

    Lijia Jiang🇩🇪 · Shanjin Wu🇨🇳 · Huichao Song🇨🇳

    In this proceeding, we investigate the dynamical evolution of the $\sigma$ field with a trajectory across the 1st order phase transition boundary, using Langevin dynamics from the linear sigma model. We find the high order cumulants of the $\sigma$ field are largely enhanced during the dynamical evolution, compared with the equilibrium values, due to the supercooling effect of the first order phase transition.

    ↳ nucl-thnucl-exEPJ Web Conf.(2018)·7 citations
15. 15*

    Chiral interactions up to next-to-next-to-next-to-leading order and nuclear saturation

    C. Drischler🇩🇪 · K. Hebeler🇩🇪 · A. Schwenk🇩🇪

    We present an efficient Monte Carlo framework for perturbative calculations of infinite nuclear matter based on chiral two-, three-, and four-nucleon interactions. The method enables the incorporation of all many-body contributions in a straightforward and transparent way, and makes it possible to extract systematic uncertainty estimates by performing order-by-order calculations in the chiral expansion as well as the many-body expansion. The versatility of this new framework is demonstrated by applying it to chiral low-momentum interactions, exhibiting a very good many-body convergence up to fourth order. Following these benchmarks, we explore new chiral interactions up to next-to-next-to-next-to-leading order (N${}^3$LO). Remarkably, simultaneous fits to the triton and to saturation properties can be achieved, while all three-nucleon low-energy couplings remain natural. The theoretical uncertainties of nuclear matter are significantly reduced when going from next-to-next-to-leading order to N${}^3$LO.

    ↳ nucl-thastro-ph.HEnucl-exPRL(2019)·391 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.