Tue·Sep 15, 2015Tuesday·September 15, 2015

1. 01*

   High precision measurement of the associated strangeness production in proton proton interactions

   COSY-TOF Collaboration: S. Jowzaee🇩🇪 · E. Borodina🇩🇪 · H. Clement🇩🇪 · E. Doroshkevich🇩🇪 · R. Dzhygadlo🇩🇪 · K. Ehrhardt🇩🇪 · W. Eyrich🇩🇪 · W. Gast🇩🇪 · A. Gillitzer🇩🇪 · D. Grzonka🇩🇪 · F. Hauenstein🇩🇪 · P. Klaja🇩🇪 and 13 other authors

   A new high precision measurement of the reaction pp -> pK+Lambda at a beam momentum of 2.95 GeV/c with more than 200,000 analyzed events allows a detailed analysis of differential observables and their inter-dependencies. Correlations of the angular distributions with momenta are examined. The invariant mass distributions are compared for different regions in the Dalitz plots. The cusp structure at the N Sigma threshold is described with the Flatté formalism and its variation in the Dalitz plot is analyzed.

   nucl-exEPJA(2016)·19 citations
2. 02*

   Results of a search for neutrinoless double-beta decay using the COBRA demonstrator

   Joachim Ebert🇩🇪 · Matthew Fritts🇩🇪 · Daniel Gehre🇩🇪 · Claus Goessling🇩🇪 · Caren Hagner🇩🇪 · Nadine Heidrich🇩🇪 · Reiner Klingenberg🇩🇪 · Kevin Kroeninger🇩🇪 · Christian Nitsch🇩🇪 · Christian Oldorf🇩🇪 · Thomas Quante🇩🇪 · Silke Rajek🇩🇪 and 9 other authors

   Neutrinoless double-$\beta$ decay ($0\nu \beta \beta$ decay) is a hypothetical process that can occur if the neutrino is its own antiparticle. The COBRA collaboration operates a demonstrator to search for these decays at the Laboratori Nazionali del Gran Sasso in Italy using CdZnTe semiconductor detectors. The exposure of $234.7$kg\,d considered in this analysis was collected between September 2011 and February 2015. The analysis focuses on the decay of the nuclides ${}^{114}$Cd, ${}^{128}$Te, ${}^{70}$Zn, ${}^{130}$Te and ${}^{116}$Cd. A Bayesian analysis is performed to estimate the signal strength of $0\nu \beta \beta$ decay. No signal is observed for any of these nuclides. Therefore, the following half-life limits at 90% credibility are set: $T_{1/2}^{0\nu }>1.6\cdot 10^{21}$yr (${}^{114}$Cd), $T_{1/2}^{0\nu }>1.9\cdot 10^{21}$yr (${}^{128}Te$), $T_{1/2}^{0\nu }>6.8\cdot 10^{18}$yr (${}^{70}$Zn), $T_{1/2}^{0\nu }>6.1\cdot 10^{21}$yr (${}^{130}$Te), and $T_{1/2}^{0\nu }>1.1\cdot 10^{21}$yr (${}^{116}$Cd).

   nucl-exphysics.ins-detPRC(2016)·52 citations
3. 03*

   Nuclear medium effect on nuclear modification factor of protons and pions in intermediate-energy heavy ion collisions

   Ming Lv🇨🇳 · Yu-Gang Ma🇨🇳 · Jin-Hui Chen🇨🇳 · De-Qing Fang🇨🇳 · Guo-Qiang Zhang🇨🇳

   Nuclear modification factor ($R_{cp}$) of protons and pions are investigated by simulating Au + Au collisions from 0.8 to 1.8$A$ GeV in a framework of an isospin-dependent quantum molecular dynamics (IQMD) model. $R_{cp}$ of protons rises with the increase of \pt~ at different beam energies owing to radial flow and Cronin effect. The rate of increase of \rcp~ is suppressed at higher beam energies. The significant difference of $R_{cp}$ between protons and pions indicates different medium effects between protons and pions. By changing the in-medium nucleon-nucleon cross section, the $R_{cp}$ of protons changes a lot, while the $R_{cp}$ of pions does not. Taking the pion absorption into account, the $R_{cp}$ of pions becomes close to unity without $p_T$ dependence after deactivating the reaction $\pi N\to \Delta$, while there is nearly no change on proton. This suggests that the pion absorption plays a dominant role on pion dynamics and have slight effect for proton dynamics.

   ↳ nucl-thnucl-exPRC(2017)·5 citations
4. 04*

   Scaling properties of inclusive W${}^{\pm }$ production at hadron colliders

   François Arleo🇫🇷 · Émilien Chapon🇫🇷 · Hannu Paukkunen🇫🇮

   We consider the hadroproduction of W gauge bosons in their leptonic decay mode. Starting from the leading-order expressions, we show that by defining a suitable scaling variable the centre-of-mass dependence of the cross sections at the LHC energies can be essentially described by a simple power law. The scaling exponent is directly linked to the small-$x$ behaviour of parton distribution functions (PDF) which, at the high virtualities involved in W production, is largely dictated by QCD evolution equations. This entails a particularly simple scaling law for the lepton charge asymmetry and also predicts that measurements in different collision systems (p-p, p-$\bar{\mathrm{p}}$, p-Pb Pb-Pb) are straightforwardly related. The expectations are compared with the existing data and a very good overall agreement is observed. It is shown that the PDF uncertainty in certain cross-section ratios between nearby centre-of-mass energies can be significantly reduced by taking the ratios at fixed value of scaling variable instead of fixed rapidity.

   ↳ hep-phhep-exnucl-exnucl-thEPJC(2016)·12 citations
5. 05*

   Symmetry violations in nuclear and neutron $\beta$ decay

   K.K. Vos🇳🇱 · H.W. Wilschut🇳🇱 · R.G.E. Timmermans🇳🇱

   The role of $\beta$ decay as a low-energy probe of physics beyond the Standard Model is reviewed. Traditional searches for deviations from the Standard Model structure of the weak interaction in $\beta$ decay are discussed in the light of constraints from the LHC and the neutrino mass. Limits on the violation of time-reversal symmetry in $\beta$ decay are compared to the strong constraints from electric dipole moments. Novel searches for Lorentz symmetry breaking in the weak interaction in $\beta$ decay are also included, where we discuss the unique sensitivity of $\beta$ decay to test Lorentz invariance. We end with a roadmap for future $\beta$-decay experiments.

   ↳ hep-phhep-exnucl-exnucl-thRMP(2015)·71 citations
6. 06*

   Non-Relativistic Approximation of Dirac Equation for Slow Fermions Coupled to the Chameleon and Torsion Fields in the Gravitational Field of the Earth

   A. N. Ivanov🇦🇹 · M. Wellenzohn🇦🇹

   We analyse a non-relativistic approximation of the Dirac equation for slow fermions, coupled to the chameleon field and torsion in the spacetime with the Schwarzschild metric, taken in the weak gravitational field of the Earth approximation. We follow the analysis of the Dirac equation in the curved spacetime with torsion, proposed by Kostelecky (Phys. Rev. D69, 105009 (2004)), and apply the Foldy--Wouthuysen transformations. We derive the effective low-energy gravitational potentials for slow fermions, coupled to the gravitational field of the Earth, the chameleon field and to torsion with minimal and non-minimal couplings.

   ↳ gr-qcastro-ph.IMhep-phnucl-ex+1PRD(2015)·10 citations
7. 07*

   Pentaquarks and Tetraquarks at LHCb

   Sheldon Stone🇺🇸

   Exotic resonant structures found in ${\Lambda }_b^0$ and ${\overline{B}}^0$ decays into charmonium in the LHCb experiment are discussed. Examination of the $J/\psi p$ system in ${\Lambda }_b^0\to J/\psi K^{-}p$ decays shows two states each of which must be composed of $uudc\overline{c}$ quarks, and thus are called charmonium pentaquarks. Their masses are $4380\pm 8\pm 29$~MeV and $4449.8\pm 1.7\pm 2.5$~MeV, and their corresponding widths ($\Gamma$) are $205\pm 18\pm 86$ MeV, and $39\pm 5\pm 19$ MeV. The preferred $J^P$ assignments are of opposite parity, with one state having spin 3/2 and the other 5/2. Models of internal binding of the pentaquark states are discussed. Finally, another mesonic state is discussed, the $Z(4430{)}^{-}$ that decays into ${\psi }^{\prime }{\pi }^{-}$ and was first observed by the Belle collaboration in $B^0\to {\psi }^{\prime }{K}^{+}{\pi }^{-}$ decays. Using a sample of approximately 25,000 signal events, LHCb determines the $J^P$ to be $1^{+}$.

   ↳ hep-exhep-phnucl-exnucl-thPoS(2015)·13 citations
8. 08*

   Electromagnetic fields and anomalous transports in heavy-ion collisions --- A pedagogical review

   Xu-Guang Huang🇨🇳

   The hot and dense matter generated in heavy-ion collisions may contain domains which are not invariant under P and CP transformations. Moreover, heavy-ion collisions can generate extremely strong magnetic fields as well as electric fields. The interplay between the electromagnetic field and triangle anomaly leads to a number of macroscopic quantum phenomena in these P- and CP-odd domains known as the anomalous transports. The purpose of the article is to give a pedagogical review of various properties of the electromagnetic fields, the anomalous transports phenomena, and their experimental signatures in heavy-ion collisions.

   ↳ nucl-thhep-phnucl-exRept.Prog.Phys.(2016)·359 citations
9. 09*

   Reduction of the $K^{\ast }$ meson abundance in heavy ion collisions

   Sungtae Cho🇰🇷 · Su Houng Lee🇰🇷

   We study the $K^{\ast }$ meson reduction in heavy ion collisions by focusing on the hadronic effects on the $K^{\ast }$ meson abundance. We evaluate the absorption cross sections of the $K^{\ast }$ and $K$ meson by light mesons in the hadronic matter, and further investigate the variation in the meson abundances for both particles during the hadronic stage of heavy ion collisions. We show how the interplay between the interaction of the $K^{\ast }$ meson and kaon with light mesons in the hadronic medium determines the final yield difference of the statistical hadronization model to the experimental measurements. For the central Au+Au collision at $\sqrt{s_{NN}}=200$ GeV, we find that the $K^{\ast }/K$ yield ratio at chemical freeze-out decreases by $36\%$ during the expansion of the hadronic matter, resulting in the final ratio comparable to STAR measurements of 0.23 $\pm 0.05$.

   ↳ nucl-thhep-phnucl-exPRC(2018)·27 citations
10. 10*

    Pseudorapidity correlations in heavy ion collisions from viscous fluid dynamics

    Akihiko Monnai🇺🇸 · Bjoern Schenke🇺🇸

    We demonstrate by explicit calculations in 3+1 dimensional viscous relativistic fluid dynamics how two-particle pseudorapidity correlation functions in heavy ion collisions at the LHC and RHIC depend on the number of particle producing sources and the transport properties of the produced medium. In particular, we present results for the Legendre coefficients of the two-particle pseudorapidity correlation function in Pb+Pb collisions at 2760 GeV and Au+Au collisions at 200 GeV from viscous hydrodynamics with three dimensionally fluctuating initial conditions. Our results suggest that these coefficients provide important constraints on initial state fluctuations and the transport properties of the quark gluon plasma.

    ↳ nucl-thhep-phnucl-exPLB(2016)·43 citations
11. 11*

    Two-particle correlations in pseudorapidity in a hydrodynamic model

    Piotr Bozek🇵🇱 · Wojciech Broniowski🇵🇱 · Adam Olszewski🇵🇱

    Two-particle pseudorapidity correlations of hadrons produced in Pb+Pb collisions at 2.76 TeV at the CERN Large Hadron Collider are analyzed in the framework of a model based on viscous 3+1-dimensional hydrodynamics with the Glauber initial condition. Based on our results, we argue that the correlation from resonance decays, formed at a late stage of the evolution, produce significant effects. In particular, their contribution to the event averages of the coefficients of the expansion in the Legendre basis explain 60-70% of the experimental values. We have proposed an accurate way to compute these <a_n a_m> coefficients, independent of the binning in pseudorapidity, and tested a double expansion of the two-particle correlation function in the azimuth and pseudorapidity, which allows us to investigate the pseudorapidity correlations between harmonics of the collective flow. In our model, these quantities are also dominated by non-flow effects from the resonance decays. Finally, our method can be used to compute higher-order cumulants for the expansion in orthonormal polynomials which offers a suitable way of eliminating the non-flow effects from the correlation analyses.

    ↳ nucl-thhep-phnucl-exPRC(2015)·21 citations
12. 12*

    Photonuclear reactions with Zinc: A case for clinical linacs

    I. Boztosun🇹🇷 · H. {\DJ}apo · M. Karakoç · S.F. Özmen · Y. Çeçen · A. Çoban · T. Caner · E.Bayram · T.R. Saito🇩🇪 · T. Akdoğan🇺🇸 · V. Bozkurt🇩🇪 · Y. Kuçuk · D. Kaya · M.N. Harakeh🇳🇱

    The use of bremsstrahlung photons produced by a linac to induce photonuclear reactions is wide spread. However, using a clinical linac to produce the photons is a new concept. We aimed to induce photonuclear reactions on zinc isotopes and measure the subsequent transition energies and half-lives. For this purpose, a bremsstrahlung photon beam of 18 MeV endpoint energy produced by the Philips SLI-25 linac has been used. The subsequent decay has been measured with a well-shielded single HPGe detector. The results obtained for transition energies are in good agreement with the literature data and in many cases surpass these in accuracy. For the half-lives, we are in agreement with the literature data, but do not achieve their precision. The obtained accuracy for the transition energies show what is achievable in an experiment such as ours. We demonstrate the usefulness and benefits of employing clinical linacs for nuclear physics experiments.

    ↳ physics.ins-detnucl-exEur.Phys.J.Plus(2015)·5 citations
13. 13*

    Robust characteristics of nongaussian fluctuations from the NJL model

    Jiunn-Wei Chen🇹🇼 · Jian Deng🇨🇳 · Hiroaki Kohyama🇹🇼 · Lance Labun🇺🇸

    We evaluate the third- and fourth-order baryon, charge and strangeness susceptibilities near a chiral critical point using the Nambu-Jona-Lasinio model. We identify robust qualitative behaviours of the susceptibilities along hypothetical freeze-out lines that agree with previous model studies. Quantitatively, baryon number fluctuations are the largest in magnitude and thus offer the strongest signal when freeze-out occurs farther away from a critical point. Charge and strangeness susceptibilities also diverge at a critical point, but the area where the divergence dominates is smaller, meaning freeze-out must occur closer to a critical point for a signal to be visible in these observables. In case of strangeness, this is attributable to the relatively large strange quark mass. Plotting the third- and fourth-order susceptibilities against each other along the freeze-out line exhibits clearly their non-montonicity and robust features.

    ↳ hep-phnucl-exnucl-thPRD(2016)·52 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.