Nuclear Theory·nucl-th

Tuesday·March 3, 2015

15 papers—6 primary·9 cross-listed

07
Effect of event selection on jetlike correlation measurement in $d$ +Au collisions at $s_{NN} = 200$ GeV
STAR Collaboration: L. Adamczyk🇵🇱 · J. K. Adkins🇺🇸 · G. Agakishiev🇷🇺 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · I. Alekseev🇷🇺 · J. Alford🇺🇸 · A. Aparin🇷🇺 · D. Arkhipkin🇺🇸 · E. C. Aschenauer🇺🇸 · G. S. Averichev🇷🇺 · A. Banerjee🇮🇳 and 320 other authors
Dihadron correlations are analyzed in $s_{_{NN}} = 200$ GeV $d$ +Au collisions classified by forward charged particle multiplicity and zero-degree neutral energy in the Au-beam direction. It is found that the jetlike correlated yield increases with the event multiplicity. After taking into account this dependence, the non-jet contribution on the away side is minimal, leaving little room for a back-to-back ridge in these collisions.
↳ nucl-exnucl-thPLB(2015)·42 citations
08
Real-Time Dynamics of an Impurity in an Ideal Bose Gas in a Trap
A. G. Volosniev · H.-W. Hammer · N. T. Zinner
We investigate the behavior of a harmonically trapped system consisting of an impurity in a dilute ideal Bose gas after the boson-impurity interaction is suddenly switched on. As theoretical framework, we use a field theory approach in the space-time domain within the T-matrix approximation. We establish the form of the corresponding T-matrix and address the dynamical properties of the system. As a numerical application, we consider a simple system of a weakly interacting impurity in one dimension where the interaction leads to oscillations of the impurity density. Moreover, we show that the amplitude of the oscillations can be driven by periodically switching the interaction on and off.
↳ cond-mat.quant-gasnucl-thquant-phPRA(2015)·47 citations
09
Collisions in Chiral Kinetic Theory
Jing-Yuan Chen🇺🇸 · Dam T. Son🇺🇸 · Mikhail A. Stephanov🇺🇸
Using a covariant formalism, we construct a chiral kinetic theory Lorentz invariant to order $O (ℏ)$ which includes collisions. We find a new contribution to the particle number current due to the side jumps required by the conservation of angular momentum during collisions. We also find a conserved symmetric stress-energy tensor as well as the $H$ -function obeying Boltzmann's $H$ -theorem. We demonstrate their use by finding a general equilibrium solution and the values of the anomalous transport coefficients characterizing chiral vortical effect.
↳ hep-thcond-mat.mes-hallnucl-thPRL(2015)·171 citations
10
The Higgs Transverse Momentum Distribution at NNLL and its Theoretical Errors
Duff Neill🇺🇸 · Ira Z. Rothstein🇺🇸 · Varun Vaidya🇺🇸
In this letter, we present the NNLL-NNLO transverse momentum Higgs distribution arising from gluon fusion. In the regime $p_{⊥} ≪ m_{H}$ we include the resummation of the large logs at next to next-to leading order and then match on to the $α_{s}^{2}$ fixed order result near $p_{⊥} \sim m_{h}$ . By utilizing the rapidity renormalization group (RRG) we are able to smoothly match between the resummed, small $p_{⊥}$ regime and the fixed order regime. We give a detailed discussion of the scale dependence of the result including an analysis of the rapidity scale dependence. Our central value differs from previous results, in the transition region as well as the tail, by an amount which is outside the error band. This difference is due to the fact that the RRG profile allows us to smoothly turn off the resummation.
↳ hep-phhep-thnucl-thJHEP(2015)·70 citations
11
Deconfinement Transition at High Isospin Chemical Potential and Low Temperature
Thomas D. Cohen🇺🇸 · Srimoyee Sen🇺🇸
We consider QCD with two degenerate flavors of light quarks(up and down) at asymptotically high isospin chemical potential with zero baryon chemical potential and calculate for the first time a quantitative expression for the critical temperature of the deconfinement transition in this regime. At high isospin chemical potential and sufficiently low temperatures this theory becomes equivalent to a pure Yang-Mills theory and accordingly has a first order deconfinement phase transition. Although this was conjectured in a seminal paper by Son and Stephanov in the year 2001, the critical temperature of this deconfinement phase transition was not computed. This paper computes the energy scale associated with this transition as a function of the isospin chemical potential by relating the parameters of the equivalent Yang-Mills theory to those of the underlying theory. We also relate the equation of state in one strongly interacting regime of QCD namely at finite isospin density to that in pure Yang-Mills, with the latter being amenable to straightforward numerical calculation. Our results for the critical temperature of deconfinement transition can be compared with future lattice calculations.
↳ hep-phhep-thnucl-thNPA(2015)·35 citations
12
Lorentz Coherence and the Proton Form Factor
Young S. Kim🇺🇸
The dipole cutoff behavior for the proton form factor has been and still is one of the major issues in high-energy physics. It is shown that this dipole behavior comes from the coherence between the Lorentz contraction of the proton size and the decreasing wavelength of the incoming photon signal. The contraction rates are the same for both cases. This form of coherence is studied also in the momentum-energy space. The coherence effect in this space can be explained in terms of two overlapping wave functions.
↳ hep-phnucl-thquant-phPhys.Scripta(2015)·0 citations
13
Photoproduction of $Λ (1405)$ with the two-pole structure
Seung-il Nam🇰🇷 · Hyun-Kyu Jo🇰🇷
We investigate the $Λ (1405, 1/ 2^{-}) \equiv Λ^{*}$ photoproduction off the proton target, i.e. $γ p \to K^{+} Λ^{*}$ , considering explicitly its two-pole structure, the higher ( $Λ_{H}^{*} : 1430 MeV$ ) and lower ( $Λ_{L}^{*} : 1390 MeV$ ) mass-pole contributions, suggested by the chiral-unitary model (ChUM) approaches. For this purpose, we construct a two-body process model, which mimics the Dalitz process, $γ p \to K^{+} π Σ$ , assuming that the mass of $Λ^{*}$ as the invariant mass of $π$ and $Σ$ , i.e. $M_{Λ^{*}} \sim M_{π Σ}$ . We employ the effective Lagrangian method with the tree-level Born approximation, using the gauge-invariant prescription for the phenomenological form factors. We provide the numerical results for the energy and angular dependences, $π$ - $Σ$ invariant-mass distribution, and so on. It turns out that the model parameters determined from ChUM reproduce the experimental data qualitatively well, supporting the two-pole structure. Moreover, the nucleon resonance contribution near the threshold plays an important role to describe the data.
↳ hep-phnucl-th9 citations
14
Analysing powers and spin correlations in deuteron-proton charge exchange at 726 MeV
S. Dymov🇩🇪 · T. Azaryan🇷🇺 · Z. Bagdasarian🇩🇪 · S. Barsov🇷🇺 · J. Carbonell🇫🇷 · D. Chiladze🇬🇪 · R. Engels🇩🇪 · R. Gebel🇩🇪 · K. Grigoryev🇩🇪 · M. Hartmann🇩🇪 · A. Kacharava🇩🇪 · A. Khoukaz🇩🇪 and 27 other authors
The charge exchange of vector polarised deuterons on a polarised hydrogen target has been studied in a high statistics experiment at the COSY-ANKE facility at a deuteron beam energy of Td = 726 MeV. By selecting two fast protons at low relative energy E_{pp}, the measured analysing powers and spin correlations are sensitive to interference terms between specific neutron-proton charge-exchange amplitudes at a neutron kinetic energy of Tn ~ 1/2 Td =363 MeV. An impulse approximation calculation, which takes into account corrections due to the angular distribution in the diproton, describes reasonably the dependence of the data on both E_{pp} and the momentum transfer. This lends broad support to the current neutron-proton partial-wave solution that was used in the estimation.
↳ nucl-exnucl-thPLB(2015)·2 citations
15
Deeply virtual Compton scattering at small- $x$ in future Electron - Ion Colliders
V. P. Goncalves🇧🇷 · D. S. Pires🇧🇷
The study of exclusive processes in the future electron-ion ( $e A$ ) colliders will be an important tool to investigate the QCD dynamics at high energies as they are in general driven by the gluon content of the target which is strongly subject to parton saturation effects. In this paper we compute the coherent and incoherent cross sections for the deeply virtual Compton scattering (DVCS) process relying on the color dipole approach and considering different models for the dipole - proton scattering amplitude. The dependencies of the cross sections with the energy, photon virtuality, nuclear mass number and squared momentum transfer are analysed in detail. We demonstrate that the ratio between the incoherent and coherent cross sections decreases at smaller values of $Q^{2}$ and increases at smaller values of $A$ . We show that the coherent cross section dominates at small $t$ and exhibits the typical diffractive pattern, with the number of dips in the range $∣ t ∣ \leq 0.3$ GeV $^{2}$ increasing with the mass atomic number. Our results indicate that the position of the dips are independent of the model used to treat the dipole - proton interaction as well as of the center-of-mass energy.
↳ hep-phhep-exnucl-exnucl-thPRC(2015)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE