Thu·Jul 2, 2015Thursday·July 2, 2015

1. 01*

   $\varphi$-meson production at forward rapidity in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV and in pp collisions at $\sqrt{s}$ = 2.76 TeV

   ALICE Collaboration

   The first study of $\varphi$-meson production in p-Pb collisions at forward and backward rapidity, at a nucleon-nucleon centre-of-mass energy $\sqrt{s_{\mathrm{NN}}}=5.02$~TeV, has been performed with the ALICE apparatus at the LHC. The $\varphi$-mesons have been identified in the dimuon decay channel in the transverse momentum ($p_{\mathrm{T}}$) range $1<p_{\mathrm{T}}<7$ GeV/$c$, both in the p-going ($2.03<y<3.53$) and the Pb-going ($-4.46<y<-2.96$) directions, where $y$ stands for the rapidity in the nucleon-nucleon centre-of-mass, the integrated luminosity amounting to $5.01\pm 0.19$~nb${}^{-1}$ and $5.81\pm 0.20$~nb${}^{-1}$, respectively, for the two data samples. Differential cross sections as a function of transverse momentum and rapidity are presented. The forward-backward ratio for $\varphi$-meson production is measured for $2.96<|y|<3.53$, resulting in a ratio $\sim 0.5$ with no significant $p_{\mathrm{T}}$ dependence within the uncertainties. The $p_{\mathrm{T}}$ dependence of the $\varphi$ nuclear modification factor $R_{\mathrm{pPb}}$ exhibits an enhancement up to a factor 1.6 at $p_{\mathrm{T}}$ = 3-4 GeV/$c$ in the Pb-going direction. The $p_{\mathrm{T}}$ dependence of the $\varphi$-meson cross section in pp collisions at $\sqrt{s}$ = 2.76 TeV, which is used to determine a reference for the p-Pb results, is also presented here for $1<p_{\mathrm{T}}<5$ GeV/$c$ and $2.5<y<4$ for a $78\pm 3$~nb${}^{-1}$ integrated luminosity sample.

   nucl-exhep-exPLB(2017)·36 citations
2. 02*

   Materials with low DC magnetic susceptibility for sensitive magnetic measurements

   Rakshya Khatiwada🇺🇸 · Lawrence Dennis · Rachel Kendrick · Marjan Khosravi · Michael Peters · Erick Smith · Mike Snow🇺🇸

   Materials with very low DC magnetic susceptibility have many scientific applications. To our knowledge however, relatively little research has been conducted with the goal to produce a totally nonmagnetic material. This phrase in our case means after spatially averaging over macroscopic volumes, it possesses an average zero DC magnetic susceptibility. We report measurements of the DC magnetic susceptibility of three different types of nonmagnetic materials at room temperature: (I) solutions of paramagnetic salts and diamagnetic liquids, (II) liquid gallium-indium alloys and (III) pressed powder mixtures of tungsten and bismuth. The lowest measured magnetic susceptibility among these candidate materials is in the order of 10^-9 cgs volume susceptibility units, about two orders of magnitude smaller than distilled water. In all cases, the measured concentration dependence of the magnetic susceptibility is consistent with that expected for the weighted sum of the susceptibilities of the separate components within experimental error. These results verify the Wiedemann additivity law and thereby realize the ability to produce materials with small but tunable magnetic susceptibility. For our particular scientific application, we are also looking for materials with the largest possible number of neutrons and protons per unit volume. The gallium-indium alloys fabricated and measured in this work possess to our knowledge the smallest ratio of volume magnetic susceptibility to nucleon number density per unit volume for a room temperature liquid, and the tungsten-bismuth pressed powder mixtures possess to our knowledge the smallest ratio of volume magnetic susceptibility to nucleon number density per unit volume for a room temperature solid. This ratio is a figure of merit for a certain class of precision experiments that search for possible exotic spin-dependent forces of Nature.

   ↳ physics.ins-detnucl-exphysics.atom-phMeasur.Sci.Tech.(2016)·4 citations
3. 03*

   Bottomonium Mesons and Strategies for Their Observation

   Stephen Godfrey🇨🇦 · Kenneth Moats (Carleton University)🇨🇦

   The $B$-factories and Large Hadron Collider experiments have demonstrated the ability to observe and measure the properties of bottomonium mesons. In order to discover missing states it is useful to know their properties to develop a successful search strategy. To this end we calculate the masses and decay properties of excited bottomonium states. We use the relativized quark model to calculate the masses and wavefunctions and the ${}^3{P}_0$ quark-pair creation model to calculate decay widths to open bottom. We also summarize results for radiative transitions, annihilation decays, hadronic transitions and production cross sections which are used to develop strategies to find these states. We find that the $b\bar{b}$ system has a rich spectroscopy that we expect to be substantially extended by the LHC and $e^{+}{e}^{-}$ experiments in the near future. Some of the most promising possibilities at the LHC are observing the ${\chi }_{b(1,2)}(3P)$, ${\chi }_{b(1,2)}(4P)$ and ${\eta }_b(3S)$ states in $\gamma {\mu }^{+}{\mu }^{-}$ final states that proceed via radiative transitions through ${\rm Y}(nS)$ intermediate states and $1^3{D}_J$ and $2^3{D}_J$ into $\gamma \gamma {\mu }^{+}{\mu }^{-}$ final states proceeding via $1^3{P}_J\to 1^3{S}_1$ and $2^3{P}_J\to 2^3{S}_1$ intermediate states respectively. Some of the most interesting possibilities in $e^{+}{e}^{-}$ collisions are studying the $1^3{D}_J$ states via $4\gamma$ cascades starting with the ${\rm Y}(3S)$ and the $3^3{P}_J$ states in $\gamma \gamma {\mu }^{+}{\mu }^{-}$ final states starting with the ${\rm Y}(4S)$ and proceeding via ${\rm Y}(nS)$ intermediate states. Completing the bottomonium spectrum is an important validation of lattice QCD calculations and a test of our understanding of bottomonium states in the context of the quark model.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2015)·183 citations
4. 04*

   Neutrinoless Double Beta Decay

   Heinrich Päs🇩🇪 · Werner Rodejohann🇩🇪

   We review the potential to probe new physics with neutrinoless double beta decay $(A,Z)\to (A,Z+2)+2e^{-}$. Both the standard long-range light neutrino mechanism as well as short-range mechanisms mediated by heavy particles are discussed. We also stress aspects of the connection to lepton number violation at colliders and the implications for baryogenesis.

   ↳ hep-phhep-exnucl-exnucl-thNew J.Phys.(2015)·153 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.