Resource
2016 EN
O. A. Gelfond · M. A. Vasiliev
$Sp(2M)$ invariant field equations in the space ${\cal M}_M$ with symmetricmatrix coordinates are classified. Analogous results are obtained forMinkowski-like subspaces of ${\cal M}_M$ which include usual $4d$ Minkowskispace as a particular case. The constructed equations are associated with thetensor products of the Fock (singleton) representation of $Sp(2M)$ of any rank${\mathbf{r }}$. The infinite set of higher-spin conserved currents multilinearin rank-one fields in ${\cal M}_M$ is found. The associated conserved chargesare supported by $({\mathbf{r }} M-\frac{{\mathbf{r }} ({\mathbf{r }}-1)}{2})-$dimensional differential forms in ${\cal M}_M$, that are closed byvirtue of the rank-$2{\mathbf{r }}$ field equations. The cohomology groups$H^p(\sigma^{\mathbf{r }}_-)$ with all $p$ and ${\mathbf{r }}$, which determinethe form of appropriate gauge fields and their field equations, are found bothfor ${\cal M}_M$ and for its Minkowski-like subspace.
Resource
2016 EN
PANDA Collaboration · B. P. Singh · W. Erni
+532 more
Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuablenew information on hadron structure appear as building blocks in the collinearfactorized description for several types of hard exclusive reactions. In thispaper, we address the possibility of accessing nucleon-to-pion ($\pi N$) TDAsfrom $\bar{p}p \to e^+e^- \pi^0$ reaction with the future \={P}ANDA detector atthe FAIR facility. At high center of mass energy and high invariant masssquared of the lepton pair $q^2$, the amplitude of the signal channel $\bar{p}p\to e^+e^- \pi^0$ admits a QCD factorized description in terms of $\pi N$ TDAsand nucleon Distribution Amplitudes (DAs) in the forward and backward kinematicregimes. Assuming the validity of this factorized description, we performfeasibility studies for measuring $\bar{p}p \to e^+e^- \pi^0$ with the\={P}ANDA detector. Detailed simulations on signal reconstruction efficiency aswell as on rejection of the most severe background channel, i.e. $\bar{p}p \to\pi^+\pi^- \pi^0$ were performed for the center of mass energy squared $s = 5$GeV$^2$ and $s = 10$ GeV$^2$, in the kinematic regions $3.0 0.5 $ in theproton-antiproton center of mass frame. Results of the simulation show that theparticle identification capabilities of the \={P}ANDA detector will allow toachieve a background rejection factor of $5\cdot 10^7$ ($1\cdot 10^7$) at low(high) $q^2$ for $s=5$ GeV$^2$, and of $1\cdot 10^8$ ($6\cdot 10^6$) at low(high) $q^2$ for $s=10$ GeV$^2$, while keeping the signal reconstructionefficiency at around $40\%$. At both energies, a clean lepton signal can bereconstructed with the expected statistics corresponding to $2$ fb$^{-1}$ ofintegrated luminosity. (.../...)
Resource
2016 EN
Alexandre Belin · Alexander Maloney
We investigate the stability of massless topological black holes in AdS_dwhen minimally coupled to a scalar field of negative mass-squared. In manycases such black holes are unstable even though the field is above the BF boundand the geometry is locally AdS. The instability depends on the choice ofboundary conditions for the scalars: scalars with non-standard (Neumann)boundary conditions tend to be more unstable, though scalars with standard(Dirichlet) boundary conditions can be unstable as well. This leads to anapparent mismatch between boundary and bulk results in the Vasiliev/Vector-likematter duality.
Resource
2016 EN
O. A. Gelfond · M. A. Vasiliev
Gauge invariant conserved conformal currents built from massless fields ofall spins in 4d Minkowski space-time and $AdS_4$ are described within theunfolded dynamics approach. The current cohomology associated with non-zeroconserved charges is found. The resulting list of charges is shown to match thespace of parameters of the conformal higher-spin symmetry algebra in fourdimensions.
Resource
2016 EN
STAR Collaboration · L. Adamczyk · J. K. Adkins
+328 more
We report the measurement of the leptonic ($e^{+}e^{-}$) decay channel of the$\phi$(1020) meson in Au+Au collisions at $\sqrt{s_{_{NN}}}$ = 200 GeV by theSTAR experiment. The transverse momentum ($p_{\rm T}$) spectrum is measured for0.1 $\le p_{\rm T} \le 2.5$ GeV/$c$ at mid-rapidity ($|y|\le1$). We obtain the$p_{\rm T}$-integrated $\phi$(1020) mass $M_{\phi}=1017.7\pm0.8 (\rm {stat.})\pm0.9 (\rm {sys.})$ MeV/$c^{2}$ and width $\Gamma_{\phi} = 8.0\pm 2.5(\rm{stat.}) \pm 2.3(\rm {sys.}) \textrm{MeV/}c^{2}$, which are within1.5\,$\sigma$ and 1.1\,$\sigma$ of the vacuum values, respectively. Nosignificant difference is observed in the measured $p_{\rm T}$ spectrum,$dN/dy$, or $\left$ of the $\phi$(1020) meson between the$e^{+}e^{-}$ and hadronic ($K^{+}K^{-}$) decay channels as measured by the sameexperiment. The experimental results are compared to a theoretical modelincluding medium-modified $\phi$(1020).
Resource
2016 EN
S. Sheludiakov · J. Ahokas · J. Järvinen
+6 more
We report on a study of the exchange tunneling reactionD+HD$\rightarrow$D$_{2}$+H in a pure solid HD matrix and in a D$_{2}$ matrixwith 0.23$\%$ HD admixture at temperatures between 130$\,$mK and 1.5$\,$K. Wefound that the exchange reaction rates,$k_{exHD}\sim3\times10^{-27}$cm$^{3}$s$^{-1}$ in the pure HD matrix, and$k_{exD_{2}}=9(4)\times10^{-28}$cm$^{-3}$ in the D$_{2}$ matrix are nearlyindependent of temperature within this range. This confirms quantum tunnellingnature of these reactions, and their ability to proceed at temperatures down toabsolute zero. Based on these observations we concluded that exchange tunnelingreaction H+H$_{2}\rightarrow$H$_{2}$+H should also proceed in a H$_{2}$ matrixat the lowest temperatures. On contrary, the recombination of H atoms in solidH$_{2}$ and D atoms in solid D$_{2}$ is substantially suppressed at the lowesttemperatures as a result of increasing of violation for resonance tunneling ofatoms when they approach each other.
Resource
2016 EN
STAR Collaboration · L. Adamczyk · J. K. Adkins
+329 more
We present measurements of 2$^{nd}$ order azimuthal anisotropy ($v_{2}$) atmid-rapidity $(|y|<1.0)$ for light nuclei d, t, $^{3}$He (for $\sqrt{s_{NN}}$ =200, 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV) and anti-nuclei $\bar{\rm d}$($\sqrt{s_{NN}}$ = 200, 62.4, 39, 27, and 19.6 GeV) and $^{3}\bar{\rm He}$($\sqrt{s_{NN}}$ = 200 GeV) in the STAR (Solenoidal Tracker at RHIC)experiment. The $v_{2}$ for these light nuclei produced in heavy-ion collisionsis compared with those for p and $\bar{\rm p}$. We observe mass ordering innuclei $v_{2}(p_{T})$ at low transverse momenta ($p_{T}<2.0$ GeV/$c$). We alsofind a centrality dependence of $v_{2}$ for d and $\bar{\rm d}$. The magnitudeof $v_{2}$ for t and $^{3}$He agree within statistical errors. Light-nuclei$v_{2}$ are compared with predictions from a blast wave model. Atomic massnumber ($A$) scaling of light-nuclei $v_{2}(p_{T})$ seems to hold for $p_{T}/A< 1.5$ GeV/$c$. Results on light-nuclei $v_{2}$ from atransport-plus-coalescence model are consistent with the experimentalmeasurements.
Resource
2016 EN
Nikolay N. Vasiliev
The most studied and most successful language models were developed andevaluated mainly for English and other close European languages, such asFrench, German, etc. It is important to study applicability of these models toother languages. The use of vector space models for Russian was recentlystudied for multiple corpora, such as Wikipedia, RuWac, lib.ru. These modelswere evaluated against word semantic similarity task. For our knowledge Twitterwas not considered as a corpus for this task, with this work we fill the gap.Results for vectors trained on Twitter corpus are comparable in accuracy withother single-corpus trained models, although the best performance is currentlyachieved by combination of multiple corpora.
Resource
2016 EN
Alexander Vasiliev
We propose a generalization of the quantum hashing technique based on thenotion of the small-bias sets. These sets have proved useful in different areasof computer science, and here their properties give an optimal construction forsuccinct quantum presentation of elements of any finite abelian group, whichcan be used in various computational and cryptographic scenarios. The knownquantum fingerprinting schemas turn out to be the special cases of the proposedquantum hashing for the corresponding abelian group.
Resource
2016 EN
Thomas Basile · Nicolas Boulanger
We derive and spell out the structure constants of the $\mathbb{Z}_2$-gradedalgebra $\mathfrak{shs}[\lambda]\,$ by using deformed-oscillators techniques in$Aq(2;\nu)\,$, the universal enveloping algebra of the Wigner-deformedHeisenberg algebra in 2 dimensions. The use of Weyl ordering of the deformedoscillators is made throughout the paper, via the symbols of the operators andthe corresponding associative, non-commutative star product. The deformedoscillator construction was used by Vasiliev in order to construct the higherspin algebras in three spacetime dimensions. We derive an expression for thestructure constants of $\mathfrak{shs}[\lambda]\,$ and show that they must obeya recurrence relation as a consequence of the associativity of the starproduct. We solve this condition and show that the $\mathfrak{hs}[\lambda]\,$structure constants are given by those postulated by Pope, Romans and Shen forthe Lone Star product.