119116726
Shocks and universal statistics in (1+1)-dimensional relativistic turbulence
We propose that statistical averages in relativistic turbulence exhibit universal properties. We consider analytically the velocity and temperature differences structure functions in the (1+1)-dimensional relativistic turbulence in which shock waves provide the main contribution to the structure functions in the inertial range. We study shock scattering, demonstrate the stability of the shock waves, and calculate the anomalous exponents. We comment on the possibility of finite time blowup singularities.
7546995
Supersymmetry Changing Bubbles in String Theory
We give examples of string compactifications to 4d Minkowski space with different amounts of supersymmetry that can be connected by spherical domain walls. The tension of these domain walls is tunably lower than the 4d Planck scale. The ``stringy'' description of these walls is known in terms of certain configurations of wrapped Dirichlet and NS branes. This construction allows us to connect a variety of vacua with 4d = 4,3,2,1 supersymmetry.
14339384
Heterotic moduli stabilization with fractional Chern-Simons invariants
We show that fractional flux from Wilson lines can stabilize the moduli of heterotic string compactifications on Calabi-Yau threefolds. We observe that the Wilson lines used in GUT symmetry breaking naturally induce a fractional flux. When combined with a hidden-sector gaugino condensate, this generates a potential for the complex structure moduli, Kahler moduli, and dilaton. This potential has a supersymmetric AdS minimum at moderately weak coupling and large volume. Notably, the necessary ingredients for this construction are often present in realistic models. We explore the type IIA dual phenomenon, which involves Wilson lines in D6-branes wrapping a three-cycle in a Calabi-Yau threefold, and comment on the nature of the fractional instantons that change the Chern-Simons invariant.
118103986
Aspects of the string theory landscape: Compactification and evolution
18223996
Beauty is attractive: Moduli trapping at enhanced symmetry points
We study quantum effects on moduli dynamics arising from the production of particles which are light at points of enhanced symmetry in moduli space. The resulting forces trap the moduli at these points. Moduli trapping occurs in time-dependent quantum field theory, as well as in systems of moving D-branes, where it leads the branes to combine into stacks. Trapping also occurs in the presence of gravity, though the range over which the moduli can roll is limited by Hubble friction. We observe that a scalar field trapped on a steep potential can induce a stage of acceleration of the universe, which we call trapped inflation. Moduli trapping ameliorates the cosmological moduli problem and may affect vacuum selection. In particular, rolling moduli are most powerfully attracted to the points of greatest symmetry. Given suitable assumptions about the dynamics of the very early universe, this effect might help to explain why among the plethora of possible vacuum states of string theory, we appear to live in one with a large number of (spontaneously broken) symmetries.
1748432
Dynamical dimension change in supercritical string theory
We study tree-level solutions to heterotic string theory in which the number of spacetime dimensions 10+n changes dynamically due to closed string tachyon condensation. Taking the large-n limit, we compute the amount by which the dilaton gradient changes during the condensation process. At leading order in n we find that the change in the invariant magnitude of the dilaton gradient compensates the change in spacelike central charge on the worldsheet, so that the total worldsheet central charges are equal at early and late times. This result supports our interpretation of the worldsheet theory as a CFT of critical central charge which describes a dynamical reduction in the total number of spacetime dimensions.
118457798
New structure around 3250 MeV in the baryonic B decay and the $D^{*}_{0}(2400)N$ molecular hadron
In this work, we first propose the isovector $nD^{*}_{0}(2400)^{0}$ molecular state to explain the enhancement structure around 3250 MeV (Xc(3250)0) in the $\varSigma_{c}^{++}\pi^{-}\pi^{-}$ invariant mass spectrum newly observed by the BaBar Collaboration. Under this molecular state configuration, both the analysis of the mass spectrum and the study of its dominant decay channel can well shed light on its resonance parameters measured by BaBar. Our investigation also shows that the isovector $nD^{*}_{0}(2400)^{0}$ molecular state can decay into $\varSigma_{c}^{++}\pi^{-}\pi^{-}$, which is consistent with experimental observation. These studies provide direct support to the isovector $nD^{*}_{0}(2400)^{0}$ molecular state assignment to Xc(3250)0.
119278047
Charged charmoniumlike state $Z_c(3900)^±$ via meson photoproduction
In this work, we explore the production of the newly observed charged charmoniumlike state $Z_c(3900)^\pm$ by the photoproduction process $\gamma p\to Z_c(3900)^+n$. Our numerical result indicates that the maximum of the calculated total cross section of $\gamma p\to Z_c(3900)^+n$ can reach up to the order of $0.1 \mu b$. Furthermore, the Dalitz plot analysis is performed by considering the Pomeron exchange as the background contribution. This analysis shows that the $Z_c(3900)^+$ signal can be distinguished from the background easily and the best energy window of searching for $Z_c(3900)^+$ is $\sqrt{s}\simeq7$ GeV, which is important information for further experimental study of $Z_c(3900)^+$ by meson photoproduction.
119289992
Is radio jet power linearly proportional to the product of central black hole mass and Eddington ratio in AGN?
A model for the relation between radio jet power and the product of central black hole (BH) mass and Eddington ratio of AGN is proposed, and the model is examined with data from the literature. We find that radio jet power positively correlates but not linearly with the product of BH mass (m in solar mass) and Eddington ratio (λ), and the power law indices (μ) are significantly less than unity for relatively low accretion (λ<0.1) AGN, Pj∝(λm)μ, in the radio galaxies and the Seyfert galaxies. This leads to a negative correlation between radio loudness and λm for the low luminosity AGN, i.e. R∝(λm)ρ with ρ=(7/6)μ−1<0, which may be attributed to a contribution of BH spin to total jet power assuming that the spin induced jet is gradually suppressed as the accretion rate increases. Whereas, for the high-z quasars which often show the slope μ≥1, a positive correlation between the radio loudness and disc luminosity is predicted. We discuss that the jet powers of the high-z FRII quasars are likely dominated by the accretion disc rather than by the BH spin.
118328964
SUBSTRUCTURE IN BULK VELOCITIES OF MILKY WAY DISK STARS
We find that Galactic disk stars near the anticenter exhibit velocity asymmetries in both the Galactocentric radial and vertical components across the midplane as well as azimuthally. These findings are based on Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) spectroscopic velocities for a sample of ~400, 000 F-type stars, combined with proper motions from the PPMXL catalog for which we have derived corrections to the zero points based in part on spectroscopically discovered galaxies and QSOs from LAMOST. In the region within 2 kpc outside the Sun's radius and ±2 kpc from the Galactic midplane, we show that stars above the plane exhibit net outward radial motions with downward vertical velocities, while stars below the plane have roughly the opposite behavior. We discuss this in the context of other recent findings, and conclude that we are likely seeing the signature of vertical disturbances to the disk due to an external perturbation.
116899209
Anomalous radiative transitions between $h_b(nP)$ and $\eta_b(mS)$ and hadronic loop effect
In this work, we introduce the hadronic loop contribution to explain the anomalous radiative transitions between $h_b(nP)$ and $\eta_b(mS)$, which was recently observed by the Belle Collaboration. Our calculation shows that the hadronic loop mechanism associated with these known decay mechanisms can explain why there exist anomalous radiative transitions between $h_b(nP)$ and $\eta_b(mS)$. This study deepens our understanding of the decay mechanism of higher bottomonium radiative decays.