Mon·May 16, 2016Monday·May 16, 2016

1. 01*

   Genuine T, CP, CPT asymmetry parameters for the entangled ${\mathbf{B}}_{\mathbf{d}}$ system

   Jose Bernabeu🇪🇸 · Francisco J. Botella🇪🇸 · Miguel Nebot (IFIC - U. Valencia)🇪🇸

   The precise connection between the theoretical T, CP, CPT asymmetries, in terms of transition probabilities between the filtered neutral meson $B_d$ states and the experimental asymmetries between the double decay rate intensities for Flavour-CP eigenstate decay products in a B-factory of entangled states, is established. This allows the identification of genuine Asymmetry Parameters in the time distribution of the asymmetries and their measurability by disentangling genuine and possible fake terms. We express the nine asymmetry parameters -- three different observables for each one of the three symmetries -- in terms of the ingredients of the Weisskopf-Wigner dynamical description of the entangled $B_d$-meson states and we obtain a global fit to their values from the BaBar collaboration experimental results. The possible fake terms are all compatible with zero and the information content of the nine asymmetry parameters is indeed different. The non-vanishing $\Delta {\mathcal{S}}_c^{\mathrm{T}}=-0.687\pm 0.020$ and $\Delta {\mathcal{S}}_c^{\mathrm{CP}}=-0.680\pm 0.021$ are impressive separate direct evidence of Time-Reversal-violation and CP-violation in these transitions and compatible with Standard Model expectations. An intriguing 2$\sigma$ effect for the Re($\theta$) parameter responsible of CPT-Violation appears which, interpreted as an upper limit, leads to $|M_{{\bar{B}}^0{\bar{B}}^0}-M_{B^0{B}^0}|<4.0\times 10^{-5}$ eV at 95\% C.L. for the diagonal flavour terms of the mass matrix. It contributes to the CP-violating $\Delta {\mathcal{C}}_c^{\mathrm{CP}}$ asymmetry parameter in an unorthodox manner -- in its $\cos (\Delta Mt)$ time dependence --, and it is accessible in facilities with non-entangled $B_d$'s, like the LHCb experiment.

   hep-phhep-exJHEP(2016)·22 citations
2. 02*

   Unification of Gauge Couplings in Radiative Neutrino Mass Models

   Claudia Hagedorn🇩🇰 · Tommy Ohlsson🇸🇪 · Stella Riad🇸🇪 · Michael A. Schmidt🇦🇺

   We investigate the possibility of gauge coupling unification in various radiative neutrino mass models, which generate neutrino masses at one- and/or two-loop level. Renormalization group running of gauge couplings is performed analytically and numerically at one- and two-loop order, respectively. We study three different classes of neutrino mass models: (I) minimal ultraviolet completions of the dimension-7 $\Delta L=2$ operators which generate neutrino masses at one- and/or two-loop level without and with dark matter candidates, (II) models with dark matter which lead to neutrino masses at one-loop level and (III) models with particles in the adjoint representation of $\mathrm{SU}(3)$. In class (I), gauge couplings unify in a few models and adding dark matter amplifies the chances for unification. In class (II), about a quarter of the models admit gauge coupling unification. In class (III), none of the models leads to gauge coupling unification. Regarding the scale of unification, we find values between $10^{14}$ GeV and $10^{16}$ GeV for models belonging to class (I) without dark matter, whereas models in class (I) with dark matter as well as models of class (II) prefer values in the range $5\cdot 10^{10}-5\cdot 10^{14}$ GeV.

   hep-phJHEP(2016)·41 citations
3. 03*

   Vortical fluid and $\Lambda$ spin correlations in high-energy heavy-ion collisions

   Long-Gang Pang (FIAS)🇩🇪 · Hannah Petersen (FIAS and ITP)🇩🇪 · Qun Wang (USTC)🇨🇳 · Xin-Nian Wang (CCNU and LBNL)🇨🇳

   Fermions become polarized in a vortical fluid due to spin-vorticity coupling. The spin polarization density is proportional to the local fluid vorticity at the next-to-leading order of a gradient expansion in a quantum kinetic theory. Spin correlations of two $\Lambda$-hyperons can therefore reveal the vortical structure of the dense matter in high-energy heavy-ion collisions. We employ a (3+1)D viscous hydrodynamic model with event-by-event fluctuating initial conditions from A MultiPhase Transport (AMPT) model to calculate the vorticity distributions and $\Lambda$ spin correlations. The azimuthal correlation of the transverse spin is shown to have a cosine form plus an offset due to a circular structure of the transverse vorticity around the beam direction and global spin polarization. The longitudinal spin correlation shows a structure of vortex-pairing in the transverse plane due to the convective flow of hot spots in the radial direction. The dependence on colliding energy, rapidity, centrality and sensitivity to the shear viscosity are also investigated.

   hep-phnucl-exnucl-thPRL(2016)·230 citations
4. 04*

   On the Origin of the $XYZ$ Mesons

   A. Valcarce🇪🇸 · J. Vijande🇪🇸

   In this talk we present a mechanism giving rise to exotic $XYZ$ four-quark states in the meson spectra within a constituent quark model approach. We discuss its generalization to five-quark states in the heavy baryon sector. Finally, we revise some other works in the literature and experimental data where this mechanism may be working.

   hep-phnucl-thAIP Conf.Proc.(2016)·0 citations
5. 05*

   Deeply bound $\Xi$ tribaryon

   H. Garcilazo🇲🇽 · A. Valcarce🇪🇸

   We have used realistic local interactions based on the recent update of the strangeness $-2$ Nijmegen ESC08c potential to calculate the bound state problem of the $\Xi NN$ system in the $(I)J^P=(\frac{1}{2}){\frac{3}{2}}^{+}$ state. We found that this system presents a deeply bound state lying $13.5$ MeV below the $\Xi d$ threshold. Since in lowest order, pure S$-$wave configuration, this system can not decay into the open $\Lambda \Lambda N$ channel, its decay width is expected to be very small. We have also recalculated the $(I)J^P=(\frac{3}{2}){\frac{1}{2}}^{+}$ state and we have compared with results of quark-model based potentials.

   hep-phnucl-thPRC(2016)·33 citations
6. 06*

   Predictions for the Majorana CP Violation Phases in the Neutrino Mixing Matrix and Neutrinoless Double Beta Decay

   I. Girardi🇮🇹 · S. T. Petcov🇮🇹 · A. V. Titov🇮🇹

   We obtain predictions for the Majorana phases ${\alpha }_{21}/2$ and ${\alpha }_{31}/2$ of the $3\times 3$ unitary neutrino mixing matrix $U=U_e^{†}{U}_{\nu }$, $U_e$ and $U_{\nu }$ being the $3\times 3$ unitary matrices resulting from the diagonalisation of the charged lepton and neutrino Majorana mass matrices, respectively. We focus on forms of $U_e$ and $U_{\nu }$ permitting to express ${\alpha }_{21}/2$ and ${\alpha }_{31}/2$ in terms of the Dirac phase $\delta$ and the three neutrino mixing angles of the standard parametrisation of $U$, and the angles and the two Majorana-like phases ${\xi }_{21}/2$ and ${\xi }_{31}/2$ present, in general, in $U_{\nu }$. The concrete forms of $U_{\nu }$ considered are fixed by, or associated with, symmetries (tri-bimaximal, bimaximal, etc.), so that the angles in $U_{\nu }$ are fixed. For each of these forms and forms of $U_e$ that allow to reproduce the measured values of the three neutrino mixing angles ${\theta }_{12}$, ${\theta }_{23}$ and ${\theta }_{13}$, we derive predictions for phase differences $({\alpha }_{21}/2-{\xi }_{21}/2)$, $({\alpha }_{31}/2-{\xi }_{31}/2)$, etc., which are completely determined by the values of the mixing angles. We show that the requirement of generalised CP invariance of the neutrino Majorana mass term implies ${\xi }_{21}=0$ or $\pi$ and ${\xi }_{31}=0$ or $\pi$. For these values of ${\xi }_{21}$ and ${\xi }_{31}$ and the best fit values of ${\theta }_{12}$, ${\theta }_{23}$ and ${\theta }_{13}$, we present predictions for the effective Majorana mass in neutrinoless double beta decay for both neutrino mass spectra with normal and inverted ordering.

   hep-phNPB(2016)·51 citations
7. 07*

   Pinning down neutrino oscillation parameters in the 2-3 sector with a mgnetised atmospheric neutrino detector: a new study

   Lakshmi S. Mohan🇮🇳 · D. Indumathi🇮🇳

   We determine the sensitivity to neutrino oscillation parameters from a study of atmospheric neutrinos in a magnetised detector such as the ICAL at the proposed India-based Neutrino Observatory. In such a detector that can {\em separately} count ${\nu }_{\mu }$ and ${\overline{\nu }}_{\mu }$-induced events, the relatively smaller (about 5\%) uncertainties on the neutrino--anti-neutrino flux ratios translate to a constraint in the ${\chi }^2$ analysis that results in a significant improvement in the precision with which neutrino oscillation parameters such as ${\sin }^2{\theta }_{23}$ can be determined. Such an effect is unique to all magnetisable detectors and constitutes a great advantage in determining neutrino oscillation parameters using such detectors. Such a study has been performed for the first time here. Along with an increase in the kinematic range compared to earlier analyses, this results in sensitivities to oscillation parameters in the 2--3 sector that are comparable to or better than those from accelerator experiments where the fluxes are significantly higher. For example, the $1\sigma$ precisions on ${\sin }^2{\theta }_{23}$ and $|\Delta m_{32(31)}^2|$ achievable for 500 kTon yr exposure of ICAL are $\sim 9\%$ and $\sim 2.5\%$ respectively for both normal and inverted hierarchies. The mass hierarchy sensitivity achievable with this combination when the true hierarchy is normal (inverted) for the same exposure is $\Delta {\chi }^2\approx 8.5$ ($\Delta {\chi }^2\approx 9.5$).

   hep-phEPJC(2017)·30 citations
8. 08*

   Unquenching the meson spectrum: a model study of excited $\rho$ resonances

   George Rupp🇵🇹 · Susana Coito🇨🇳 · Eef van Beveren🇵🇹

   Quark models taking into account the dynamical effects of hadronic decay often produce very different predictions for mass shifts in the hadron spectrum. The consequences for meson spectroscopy can be dramatic and completely obscure the underlying confining force. Recent unquenched lattice calculations of mesonic resonances that also include meson-meson interpolators provide a touchstone for such models, despite the present limitations in applicability. On the experimental side, the $\rho (770)$ meson and its several observed radial recurrences are a fertile testing ground for both quark models and lattice computations. Here we apply a unitarised quark model that has been successful in the description of many enigmatic mesons to these vector $\rho$ resonances and the corresponding $P$-wave $\pi \pi$ phase shifts. This work is in progress, with encouraging preliminary results.

   hep-phhep-exActa Phys.Polon.Supp.(2016)·9 citations
9. 09*

   Charge specific baryon mass relations with deformed SU_q(3) flavor symmetry

   Niels G. Gresnigt🇨🇳

   The quantum group $S{U}_q(3)=U_q(su(3))$ is taken as a baryon flavor symmetry. Accounting for electromagnetic contributions to baryons masses to zeroth order, new charge specific $q$-deformed octet and decuplet baryon mass formulas are obtained. These new mass relations have errors of only 0.02\% and 0.08\% respectively; a factor of 20 reduction compared to the standard Gell-Mann-Okubo mass formulas. A new relation between the octet and decuplet baryon masses that is accurate to 1.2\% is derived. An explicit formula for the Cabibbo angle, taken to be $\frac{\pi }{14}$, in terms of the deformation parameter $q$ and spin parity $J^P$ of the baryons is obtained.

   hep-phEPJA(2016)·3 citations
10. 10*

    Reionization and dark matter decay

    Isabel M. Oldengott🇩🇪 · Daniel Boriero🇩🇪 · Dominik J. Schwarz🇩🇪

    Cosmic reionization and dark matter decay can impact observations of the cosmic microwave sky in a similar way. A simultaneous study of both effects is required to constrain unstable dark matter from cosmic microwave background observations. We compare two reionization models with and without dark matter decay. We find that a reionization model that fits also data from quasars and star forming galaxies results in tighter constraints on the reionization optical depth ${\tau }_{\text{reio}}$, but weaker constraints on the spectral index $n_{\text{s}}$ than the conventional parametrization. We use the Planck 2015 data to constrain the effective decay rate of dark matter to ${\Gamma }_{\mathrm{eff}}<2.9\times 10^{-25}/$s at $95$\% C.L. This limit is robust and model independent. It holds for any type of decaying dark matter and it depends only weakly on the chosen parametrization of astrophysical reionization. For light dark matter particles that decay exclusively into electromagnetic components this implies a limit of $\Gamma <5.3\times 10^{-26}/$s at $95$\% C.L. Specifying the decay channels, we apply our result to the case of keV-mass sterile neutrinos as dark matter candidates and obtain constraints on their mixing angle and mass, which are comparable to the ones from the diffuse X-ray background.

    ↳ astro-ph.COhep-phJCAP(2016)·36 citations
11. 11*

    Applying Bayesian parameter estimation to relativistic heavy-ion collisions: simultaneous characterization of the initial state and quark-gluon plasma medium

    Jonah E. Bernhard🇺🇸 · J. Scott Moreland🇺🇸 · Steffen A. Bass🇺🇸 · Jia Liu🇺🇸 · Ulrich Heinz🇺🇸

    We quantitatively estimate properties of the quark-gluon plasma created in ultra-relativistic heavy-ion collisions utilizing Bayesian statistics and a multi-parameter model-to-data comparison. The study is performed using a recently developed parametric initial condition model, TRENTO, which interpolates among a general class of particle production schemes, and a modern hybrid model which couples viscous hydrodynamics to a hadronic cascade. We calibrate the model to multiplicity, transverse momentum, and flow data and report constraints on the parametrized initial conditions and the temperature-dependent transport coefficients of the quark-gluon plasma. We show that initial entropy deposition is consistent with a saturation-based picture, extract a relation between the minimum value and slope of the temperature-dependent specific shear viscosity, and find a clear signal for a nonzero bulk viscosity.

    ↳ nucl-thhep-phnucl-exPRC(2016)·595 citations
12. 12*

    Mirror quintic vacua: hierarchies and inflation

    Nana Cabo Bizet🇿🇦 · Oscar Loaiza-Brito🇲🇽 · Ivonne Zavala🇬🇧

    We study the moduli space of type IIB string theory flux compactifications on the mirror of the CY quintic 3-fold in P4. We focus on the dynamics of the four dimensional moduli space, defined by the axio-dilaton {\tau} and the complex structure modulus z. The z-plane has critical points, the conifold, the orbifold and the large complex structure with non trivial monodromies. We find the solutions to the Picard-Fuchs equations obeyed by the periods of the CY in the full z-plane as a series expansion in z around the critical points to arbitrary order. This allows us to discard fake vacua, which appear as a result of keeping only the leading order term in the series expansions. Due to monodromies vacua are located at a given sheet in the z-plane. A dS vacuum appears for a set of fluxes. We revisit vacua with hierarchies among the 4D and 6D physical scales close to the conifold point and compare them with those found at leading order in [1, 2]. We explore slow-roll inflationary directions of the scalar potential by looking at regions where the multi-field slow-roll parameters {\epsilon} and {\eta} are smaller than one. The value of {\epsilon} depends strongly on the approximation of the periods and to achieve a stable value, several orders in the expansion are needed. We do not find realisations of single field axion monodromy inflation. Instead, we find that inflationary regions appear along linear combinations of the four real field directions and for certain configurations of fluxes.

    ↳ hep-thgr-qchep-phJHEP(2016)·47 citations
13. 13*

    Improved limits on interactions of low-mass spin-0 dark matter from atomic clock spectroscopy

    Y. V. Stadnik🇦🇺 · V. V. Flambaum🇦🇺

    Low-mass (sub-eV) spin-0 dark matter particles, which form a coherently oscillating classical field $\varphi ={\varphi }_0\cos (m_{\varphi }t)$, can induce oscillating variations in the fundamental constants through their interactions with the Standard Model sector. We calculate the effects of such possible interactions, which may include the linear interaction of $\varphi$ with the Higgs boson, on atomic and molecular transitions. Using recent atomic clock spectroscopy measurements, we derive new limits on the linear interaction of $\varphi$ with the Higgs boson, as well as its quadratic interactions with the photon and light quarks. For the linear interaction of $\varphi$ with the Higgs boson, our derived limits improve on existing constraints by up to $2-3$ orders of magnitude.

    ↳ physics.atom-phastro-ph.COhep-phnucl-thPRA(2016)·71 citations
14. 14*

    From Extended theories of Gravity to Dark Matter

    Sayantan Choudhury🇮🇳 · Manibrata Sen🇮🇳 · Soumya Sadhukhan🇮🇳

    In this work, we propose different models of extended theories of gravity, which are minimally coupled to the SM fields, to explain the possibility of a dark matter (DM) candidate, without ad-hoc additions to the Standard Model (SM). We modify the gravity sector by allowing quantum corrections motivated from local $f(R)$ gravity, and non-minimally coupled gravity with SM sector and dilaton field. Using an effective field theory (EFT) framework, we constrain the scale of the EFT and DM mass. We consider two cases-Light DM (LDM) and Heavy DM (HDM), and deduce upper bounds on the DM annihilation cross section to SM particles.

    ↳ hep-thastro-ph.COgr-qchep-phActa Phys.Polon.Supp.(2016)·3 citations
15. 15*

    Sensitivity of atom interferometry to ultralight scalar field dark matter

    Andrew A. Geraci🇺🇸 · Andrei Derevianko🇺🇸

    We discuss the use of atom interferometry as a tool to search for Dark Matter (DM) composed of ultra-light scalar fields. Previous work on ultra-light DM detection using accelerometers has considered the possibility of equivalence principle violating effects whereby gradients in the dark matter field can directly produce relative accelerations between media of differing composition. In atom interferometers, we find that time-varying phase signals from oscillatory, or dilaton-like, DM can also arise due to changes in the atom rest mass that can occur between light-pulses throughout the interferometer sequence as well as changes in the earth's gravitational field. We estimate that several orders of magnitude of unexplored phase space for light DM fields can be probed with our proposed method.

    ↳ physics.atom-phastro-ph.IMhep-phPRL(2016)·89 citations
16. 16*

    Study of the phase diagram of dense two-color QCD within lattice simulation

    V. V. Braguta🇷🇺 · E.-M. Ilgenfritz🇷🇺 · A. Yu. Kotov🇷🇺 · A. V. Molochkov🇷🇺 · A. A. Nikolaev🇷🇺

    In this paper we carry out a low-temperature scan of the phase diagram of dense two-color QCD with $N_f=2$ quarks. The study is conducted using lattice simulation with rooted staggered quarks. At small chemical potential we observe the hadronic phase, where the theory is in a confining state, chiral symmetry is broken, the baryon density is zero and there is no diquark condensate. At the critical point $\mu =m_{\pi }/2$ we observe the expected second order transition to Bose-Einstein condensation of scalar diquarks. In this phase the system is still in confinement in conjunction with non-zero baryon density, but the chiral symmetry is restored in the chiral limit. We have also found that in the first two phases the system is well described by chiral perturbation theory. For larger values of the chemical potential the system turns into another phase, where the relevant degrees of freedom are fermions residing inside the Fermi sphere, and the diquark condensation takes place on the Fermi surface. In this phase the system is still in confinement, chiral symmetry is restored and the system is very similar to the quarkyonic state predicted by SU($N_c$) theory at large $N_c$.

    ↳ hep-lathep-phnucl-thPRD(2016)·93 citations
17. 17*

    Thermalization and hydrodynamization in the color-flux-tube model

    Radoslaw Ryblewski🇵🇱

    The study of transverse-momentum spectra of quarks and gluons produced by the color electric flux tube decaying through the Schwinger tunneling mechanism is reviewed. The hints for a fast hydrodynamization in the ultra-relativistic heavy-ion collisions are found.

    ↳ nucl-thhep-phActa Phys.Polon.Supp.(2016)·0 citations
18. 18*

    Constraints on interacting dark energy models from Planck 2015 and redshift-space distortion data

    André A. Costa🇧🇷 · Xiao-Dong Xu🇿🇦 · Bin Wang🇨🇳 · E. Abdalla🇧🇷

    We investigate phenomenological interactions between dark matter and dark energy and constrain these models by employing the most recent cosmological data including the cosmic microwave background radiation anisotropies from Planck 2015, Type Ia supernovae, baryon acoustic oscillations, the Hubble constant and redshift-space distortions. We find that the interaction in the dark sector parameterized as an energy transfer from dark matter to dark energy is strongly suppressed by the whole updated cosmological data. On the other hand, an interaction between dark sectors with the energy flow from dark energy to dark matter is proved in better agreement with the available cosmological observations. This coupling between dark sectors is needed to alleviate the coincidence problem.

    ↳ astro-ph.COgr-qchep-phJCAP(2017)·144 citations
19. 19*

    Large mass hierarchies from strongly-coupled dynamics

    Andreas Athenodorou🇨🇾 · Ed Bennett🇬🇧 · Georg Bergner🇨🇭 · Daniel Elander🇿🇦 · C.-J. David Lin🇹🇼 · Biagio Lucini🇬🇧 · Maurizio Piai🇬🇧

    Besides the Higgs particle discovered in 2012, with mass 125 GeV, recent LHC data show tentative signals for new resonances in diboson as well as diphoton searches at high center-of-mass energies (2 TeV and 750 GeV, respectively). If these signals are confirmed (or other new resonances are discovered at the TeV scale), the large hierarchies between masses of new bosons require a dynamical explanation. Motivated by these tentative signals of new physics, we investigate the theoretical possibility that large hierarchies in the masses of glueballs could arise dynamically in new strongly-coupled gauge theories extending the standard model of particle physics. We study lattice data on non-Abelian gauge theories in the (near-)conformal regime as well as a simple toy model in the context of gauge/gravity dualities. We focus our attention on the ratio $R$ between the mass of the lightest spin-2 and spin-0 resonances, that for technical reasons is a particularly convenient and clean observable to study. For models in which (non-perturbative) large anomalous dimensions arise dynamically, we show indications that this mass ratio can be large, with $R>5$. Moreover, our results suggest that $R$ might be related to universal properties of the IR fixed point. Our findings provide an interesting step towards understanding large mass ratios in the non-perturbative regime of quantum field theories with (near) IR conformal behaviour.

    ↳ hep-thhep-lathep-phJHEP(2016)·32 citations
20. 20*

    Scattering amplitudes from a deconstruction of Feynman diagrams

    M. Maniatis🇨🇱 · C. M. Reyes🇨🇱

    We show how to apply the BCFW recursion relation to Feynman loop integrals with the help of the Feynman-tree theorem. We deconstruct in this way all Feynman diagrams in terms of on-shell subamplitudes. Every cut originating from the Feynman-tree theorem corresponds to an integration over the phase space of an unobserved particle pair. We argue that we can calculate scattering amplitudes alternatively by the construction of on-shell and gauge-invariant subamplitudes.

    ↳ hep-thhep-ph5 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.