Nuclear Theory·nucl-th

Tuesday·May 31, 2016

12 papers—5 primary·7 cross-listed

06
[Submitted on 1 Apr 2016] (cross-list from astro-ph.HE)
The influence of quantum vacuum friction on pulsars
Jaziel G. Coelho · Jonas P. Pereira · José C. N. de Araujo
We firstly revisit the energy loss mechanism known as quantum vacuum friction (QVF), clarifying some of its subtleties. Then we investigate the observables that could easily differentiate QVF from the classical magnetic dipole radiation for pulsars with braking indices (n) measured accurately. We show this is specially the case for the time evolution of a pulsar's magnetic dipole direction ( $ϕ ˙$ ) and surface magnetic field ( $B ˙_{0}$ ). As it is well known in the context of the classic magnetic dipole radiation, $n < 3$ would only be possible for positive $(B ˙_{0} / B_{0} + ϕ ˙ / tan ϕ)$ , which, for instance, leads to $B ˙_{0} > 0$ ( $ϕ ˙ > 0$ ) when $ϕ$ ( $B_{0}$ ) is constant. On the other hand, we show that QVF can result in very contrasting predictions with respect to the above ones. Finally, even in the case $B ˙_{0}$ in both aforesaid models for a pulsar has the same sign, for a given $ϕ$ , we show that they give rise to different associated timescales, which could be another way to falsify QVF.
Comments:
7 pages, 3 figures. Accepted for publication in ApJ
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
1604.00430 [pdf]
ApJ(2016)·16 citations
07
[Submitted on 28 May 2016] (cross-list from hep-ph)
Bethe-Salpeter bound-state structure in Minkowski space
C. Gutierrez🇧🇷 · V. Gigante🇧🇷 · T. Frederico🇧🇷 · G. Salmè🇮🇹 · M. Viviani🇮🇹 · Lauro Tomio🇧🇷
The quantitative investigation of the scalar Bethe-Salpeter equation in Minkowski space, within the ladder-approximation framework, is extended to include the excited states. This study has been carried out for an interacting system composed by two massive bosons exchanging a massive scalar, by adopting (i) the Nakanishi integral representation of the Bethe-Salpeter amplitude, and (ii) the formally exact projection onto the null plane. Our analysis, on one hand, confirms the reliability of the method already applied to the ground state and, on the other one, extends the investigation from the valence distribution in momentum space to the corresponding quantity in the impact-parameter space, pointing out some relevant features, like (i) the equivalence between Minkowski and Euclidean transverse-momentum amplitudes, and (ii) the leading exponential fall-off of the valence wave function in the impact-parameter space.
Comments:
15 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1605.08837 [pdf]
PLB(2016)·32 citations
08
[Submitted on 28 May 2016] (cross-list from hep-ph)
Asymmetric vector mesons produced in nuclear collisions
I.M. Dremin🇷🇺 · V.A. Nechitailo🇷🇺
It is argued that the experimentally observed phenomenon of asymmetric shapes of vector mesons produced in nuclear media during high energy nucleus-nucleus collisions can be explained as Fano-Feshbach resonances. It has been observed that the mass distributions of lepton pairs created at meson decays decline from the traditional Breit-Wigner shape with some excess in the low-mass wing of the resonance. It is clear that the whole phenomenon is related to some interaction with the nuclear medium. Moreover, it can be further detalized in quantum mechanics as the interference of direct and continuum states in Fano-Feshbach effect. To reveal the nature of the interaction it is proposed to use a phenomenological model of the additional contribution due to Cherenkov gluons. They can be created because of the excess of the refractivity index over 1 just in the low-mass wing as required by the classical Cherenkov treatment. In quantum mechanics, this requirement is related to the positive real part of the interaction amplitude in this wing. The corresponding parameters are found from the comparison with $ρ$ -meson data and admit reasonable explanation.
Comments:
11 pages, 2 Figures. arXiv admin note: text overlap with arXiv:1505.06297
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1605.08850 [pdf]
EPJA(2016)·0 citations
09
[Submitted on 29 May 2016] (cross-list from hep-ph)
Right-Handed Neutrinos and T-Violating, P-Conserving Interactions
Basem Kamal El-Menoufi🇺🇸 · Michael J. Ramsey-Musolf🇺🇸 · Chien-Yeah Seng🇺🇸
We show that experimental probes of the P-conserving, T-violating triple correlation in polarized neutron or nuclear $β$ -decay provide a unique probe of possible T-violation at the TeV scale in the presence of right-handed neutrinos. In contrast to other possible sources of semileptonic T-violation involving only left-handed neutrinos, those involving right-handed neutrinos are relatively unconstrained by present limits on the permanent electric dipole moments of the electron, neutral atoms, and the neutron. On the other hand, LHC results for $pp \to e +$ missing transverse energy imply that an order of magnitude of improvement in $D$ -coefficient sensitivity would be needed for discovery. Finally, we discuss the interplay with the scale of neutrino mass and naturalness considerations.
Comments:
6 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1605.09060 [pdf]
PLB(2017)·10 citations
10
[Submitted on 30 May 2016] (cross-list from hep-th)
A semi-classical recipe for wobbly limp noodles in partonic soup
R. W. Moerman🇿🇦 · W. A. Horowitz🇿🇦
We compute the average squared distance, $s^{2} (t)$ , travelled by a light-flavour off-mass-shell coloured parton in a strongly-coupled $N = 4$ $S U (N_{c})$ super-symmetric Yang Mills plasma using the gauge/string duality. In fact, we derive a closed integral expression for $s^{2} (t; a)$ in $A d S_{3}$ -Schwarzschild, which interpolates between a heavy quark when $a = 0$ and a light quark when $a = 1$ , that we evaluate analytically for small virtualities - labelled $s_{small}^{2} (t; a)$ . For arbitrary virtualities, we show that for asymptotically early times the motion is ballistic, $s^{2} (t; a)_{t ≪ β} \sim t^{2}$ , while at asymptotically late times the motion is diffusive, $s^{2} (t; a)_{t ≫ β} = s_{small}^{2} (t; a) \sim 2 D (a) t$ , from which we are able to extract the diffusion coefficient $D (a)$ . Motivated by the apparent universality of the late time behaviour, we compute $s_{small}^{2} (t; a, d)$ and $D (a, d)$ for an arbitrary $A d S_{d}$ -Schwarzschild geometry. From $D (a, d)$ we then compute for the first time the dynamic, time-dependent transverse momentum squared per unit path length picked up by a high momentum light quark in a strongly-coupled plasma, the transport coefficient $q^(t)$ , which is critically important for phenomenology in heavy ion collisions.
Comments:
36 pages, 7 figures
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1605.09285 [pdf]
21 citations
11
[Submitted on 30 May 2016] (cross-list from cond-mat.mes-hall)
Renormalization group analysis of graphene with a supercritical Coulomb impurity
Yusuke Nishida
We develop a field-theoretic approach to massless Dirac fermions in a supercritical Coulomb potential. By introducing an Aharonov--Bohm solenoid at the potential center, the critical Coulomb charge can be made arbitrarily small for one partial-wave sector, where a perturbative renormalization group analysis becomes possible. We show that a scattering amplitude for reflection of particle at the potential center exhibits the renormalization group limit cycle, i.e., log-periodic revolutions as a function of the scattering energy, revealing the emergence of discrete scale invariance. This outcome is further incorporated in computing the induced charge and current densities, which turn out to have power-law tails with coefficients log-periodic with respect to the distance from the potential center. Our findings are consistent with the previous prediction obtained by directly solving the Dirac equation and can in principle be realized by graphene experiments with charged impurities.
Comments:
7 pages; published version
Subjects:
Mesoscale and Nanoscale Physics (cond-mat.mes-hall); Nuclear Theory (nucl-th)
arXiv:
1605.09309 [pdf]
PRB(2016)·6 citations
12
[Submitted on 24 May 2016] (cross-list from cond-mat.stat-mech)
Non- Markovian Quantum Stochastic Equation For Two Coupled Oscillators
E.X. Alpomishev · Z. Kanokov
The system of nonlinear Langevin equations was obtained by using Hamiltonian's operator of two coupling quantum oscillators which are interacting with heat bath. By using the analytical solution of these equations, the analytical expressions for transport coefficients was found. Generalized Langevin equations and fluctuation-dissipation relations are derived for the case of a nonlinear non-Markovian noise. The explicit expressions for the time-dependent friction and diffusion coefficients are presented for the case of linear couplings in the coordinate between the collective two coupled harmonic oscillators and heat bath.
Comments:
17 pages. arXiv admin note: text overlap with arXiv:gr-qc/9403054 by other authors
Subjects:
Statistical Mechanics (cond-mat.stat-mech); Nuclear Theory (nucl-th)
arXiv:
1605.09327 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE

The influence of quantum vacuum friction on pulsars

Bethe-Salpeter bound-state structure in Minkowski space

Asymmetric vector mesons produced in nuclear collisions

Right-Handed Neutrinos and T-Violating, P-Conserving Interactions

A semi-classical recipe for wobbly limp noodles in partonic soup

Renormalization group analysis of graphene with a supercritical Coulomb impurity

Non- Markovian Quantum Stochastic Equation For Two Coupled Oscillators

Affiliations