Mon·May 6, 2019Monday·May 6, 2019

1. 01*

   Global view of QCD axion stars

   Joshua Eby🇮🇱 · Madelyn Leembruggen🇺🇸 · Lauren Street🇺🇸 · Peter Suranyi🇺🇸 · L.C.R. Wijewardhana🇺🇸

   Taking a comprehensive view, including a full range of boundary conditions, we reexamine QCD axion star solutions based on the relativistic Klein-Gordon equation (using the Ruffini-Bonazzola approach) and its non-relativistic limit, the Gross-Pitaevskii equation. A single free parameter, conveniently chosen as the central value of the wavefunction of the axion star, or alternatively the chemical potential with range $-m<\mu <0$ (where $m$ is the axion mass), uniquely determines a spherically-symmetric ground state solution, the axion condensate. We clarify how the interplay of various terms of the Klein-Gordon equation determines the properties of solutions in three separate regions: the structurally stable (corresponding to a local energy minimum) dilute and dense regions, and the intermediate, structurally unstable transition region. From the Klein-Gordon equation, one can derive alternative equations of motion including the Gross-Pitaevskii and Sine-Gordon equations, which have been used previously to describe axion stars in the dense region. In this work, we clarify precisely how and why such methods break down as the binding energy increases, emphasizing the necessity of using the full relativistic Klein-Gordon approach. Finally, we point out that, even after including perturbative axion number violating corrections, solutions to the equations of motion, which assume approximate conservation of axion number, break down completely in the regime with strong binding energy, where the magnitude of the chemical potential approaches the axion mass.

   hep-phastro-ph.COhep-thPRD(2019)·57 citations
2. 02*

   QCD equation of state at finite baryon density with fugacity expansion

   Volodymyr Vovchenko🇩🇪 · Jan Steinheimer🇩🇪 · Owe Philipsen🇩🇪 · Horst Stoecker🇩🇪

   We explore the QCD equation of state at finite baryon density through an expansion in baryon number fugacity, making use of the recent lattice data on the four leading Fourier coefficients of the expansion. A state-of-the-art description of the lattice data at both imaginary ${\mu }_B$ and ${\mu }_B=0$ is provided by the cluster expansion model (CEM). The CEM pressure function has three temperature dependent input parameters, which we fix by parameterizing the available lattice QCD data. This results in a crossover model of the QCD equation of state at finite baryon density, which can be used in fluid dynamical simulations of heavy-ion collisions.

   hep-phnucl-thPoS(2019)·6 citations
3. 03*

   Strong and electromagnetic amplitudes of the $J/\psi$ decays into baryons and their relative phase

   Rinaldo Baldini Ferroli🇮🇹 · Alessio Mangoni🇮🇹 · Simone Pacetti🇮🇹 · Kai Zhu🇨🇳

   The Feynman amplitude for the decay of the $J/\psi$ meson into baryon-antibaryon can be written as a sum of three sub-amplitudes: a purely strong, a purely electromagnetic and a mixed strong-electromagnetic. Assuming that the strong and mixed strong-electromagnetic sub-amplitudes have the same phase, the branching ratio of the decay contains an interference term that depends on the relative phase $\phi$ between strong and electromagnetic sub-amplitudes. In this work we calculate this phase, by using an effective strong Lagrangian density and considering, as final states, pairs of baryons, $\mathcal{B}\overline{\mathcal{B}}$, belonging to the spin-1/2 SU(3) octet. Moreover, we obtain the purely strong, purely electromagnetic and mixed strong-electromagnetic contributions to the total branching ratio and hence the moduli of the corresponding sub-amplitudes, for each pair of baryons. Of particular interest is the mixed strong-electromagnetic contribution that, not only is determined for the first time, but it is proven to be crucial, in the framework of our model, for the correct description of the decay mechanism. Finally we use the purely electromagnetic branching ratio to calculate the Born non-resonant cross section of the annihilation processes $e^{+}{e}^{-}\to \mathcal{B}\overline{\mathcal{B}}$ at the $J/\psi$ mass. By taking advantage from all available data, we obtain the relative phase between strong and electromagnetic sub-amplitudes: $\phi =(73\pm 8{)}^{\circ }$.

   hep-phPLB(2019)·36 citations
4. 04*

   Flavored Axions

   Robert Ziegler🇨🇭

   Precision flavor experiments can look for the QCD axion complementarily to usual searches with axion helio- and haloscopes, allowing to test PQ breaking scales as high as $10^{12}\mathrm{GeV}$. Such searches are sensitive to flavor-violating axion couplings, which are generic and potentially sizable whenever SM fermions carry flavor non-universal PQ charges. A particularly predictive scenario is obtained when PQ is identified with the simplest FN flavor symmetry, so that all flavor-violating axion couplings are related to Yukawa hierarchies, up to $\mathcal{O}(1)$ coefficients.

   hep-phPoS(2019)·7 citations
5. 05*

   One-loop corrections to multiscale effective vertices in the EFT for Multi-Regge processes in QCD

   Maxim Nefedov🇩🇪

   The computation of one-loop corrections to the ${\gamma }^{\star }{Q}_{+}q$ and $g{R}_{+}g$ effective vertices in the framework of gauge-invariant effective theory for Multi-Regge processes in QCD is reviewed. Due to consistent implementation of the "tilted Wilson line" regularization for rapidity divergences, the gauge-invariance has been preserved at all stages of calculation independently on the rapidity regulator and cancellation of the power-like dependence on the regularization variable is traced. Only single-logarithmic rapidity divergence is left in the final result.

   hep-phhep-thPoS(2019)·6 citations
6. 06*

   Alternative coalescence model for deuteron, tritium, helium-3 and their antinuclei

   M. Kachelriess🇳🇴 · S. Ostapchenko🇩🇪 · J. Tjemsland🇳🇴

   Antideuteron and antihelium nuclei have been proposed as a detection channel for dark matter annihilations and decays in the Milky Way, due to the low astrophysical background expected. To estimate both the signal for various dark matter models and the astrophysical background, one employs usually the coalescence model in a Monte Carlo framework. This allows one to treat the production of antinuclei on an event-by-event basis, taking thereby into account momentum correlations between the antinucleons involved in the process. This approach lacks however an underlying microscopic picture, and the numerical value of the coalescence parameter obtained from fits to different reactions varies considerably. Here we propose instead to combine event-by-event Monte Carlo simulations with a microscopic coalescence picture based on the Wigner function representations of the produced antinuclei states. This approach allows us to include in a semi-classical picture both the size of the formation region, which is process dependent, and momentum correlations. The model contains a single, universal parameter which is fixed by fitting the production spectra of antideuterons in proton-proton interactions, measured at the Large Hadron Collider. Using this value, the model describes well the production of various antinuclei both in electron-positron annihilation and in proton-proton collisions.

   hep-phEPJA(2020)·54 citations
7. 07*

   Primordial Black Holes as Silver Bullets for New Physics at the Weak Scale

   Gianfranco Bertone🇳🇱 · Adam Coogan🇳🇱 · Daniele Gaggero🇪🇸 · Bradley J. Kavanagh🇳🇱 · Christoph Weniger🇳🇱

   Observational constraints on gamma rays produced by the annihilation of weakly interacting massive particles around primordial black holes (PBHs) imply that these two classes of Dark Matter candidates cannot coexist. We show here that the successful detection of one or more PBHs by radio searches (with the Square Kilometer Array) and gravitational waves searches (with LIGO/Virgo and the upcoming Einstein Telescope) would set extraordinarily stringent constraints on virtually all weak-scale extensions of the Standard Model with stable relics, including those predicting a WIMP abundance much smaller than that of Dark Matter. Upcoming PBHs searches have in particular the potential to rule out almost the entire parameter space of popular theories such as the minimal supersymmetric standard model and scalar singlet Dark Matter.

   hep-phastro-ph.HEPRD(2019)·55 citations
8. 08*

   Distinguishing Dirac and Majorana neutrinos by their gravi-majoron decays

   Lena Funcke🇨🇦 · Georg Raffelt🇩🇪 · Edoardo Vitagliano🇩🇪

   Neutrinos may acquire small Dirac or Majorana masses by new low-energy physics in terms of the chiral gravitational anomaly, as proposed by Dvali and Funcke (2016). This model predicts fast neutrino decays, ${\nu }_i\to {\nu }_j+\varphi$ and ${\nu }_i\to {\bar{\nu }}_j+\varphi$, where the gravi-majorons $\varphi$ are pseudoscalar Nambu-Goldstone bosons. The final-state neutrino and antineutrino distributions differ depending on the Dirac or Majorana mass of the initial state. This opens a channel for distinguishing these cases, for example in the spectrum of high-energy astrophysical neutrinos. In particular, we put bounds on the neutrino lifetimes in the Majorana case, ${\tau }_2/m_2>1.1\times 10^{-3}(6.7\times 10^{-4})s/eV$ and ${\tau }_3/m_3>2.2\times 10^{-5}(1.3\times 10^{-4})s/eV$ at 90% CL for hierarchical (degenerate) masses, using data from experiments searching for antineutrino appearance from the Sun.

   hep-phPRD(2020)·66 citations
9. 09*

   Light majoron cold dark matter from topological defects and the formation of boson stars

   Mario Reig🇪🇸 · José W.F. Valle🇪🇸 · Masaki Yamada🇺🇸

   We show that for a relatively light majoron ($\ll 100$ eV) non-thermal production from topological defects is an efficient production mechanism. Taking the type I seesaw as benchmark scheme, we estimate the primordial majoron abundance and determine the required parameter choices where it can account for the observed cosmological dark matter. The latter is consistent with the scale of unification. Possible direct detection of light majorons with future experiments such as PTOLEMY and the formation of boson stars from the majoron dark matter are also discussed.

   hep-phastro-ph.COJCAP(2019)·33 citations
10. 10*

    Dark Radiation and Superheavy Dark Matter from Black Hole Domination

    Dan Hooper🇺🇸 · Gordan Krnjaic🇺🇸 · Samuel D. McDermott🇺🇸

    If even a relatively small number of black holes were created in the early universe, they will constitute an increasingly large fraction of the total energy density as space expands. It is thus well-motivated to consider scenarios in which the early universe included an era in which primordial black holes dominated the total energy density. Within this context, we consider Hawking radiation as a mechanism to produce both dark radiation and dark matter. If the early universe included a black hole dominated era, we find that Hawking radiation will produce dark radiation at a level $\Delta N_{\mathrm{eff}}\sim 0.03-0.2$ for each light and decoupled species of spin 0, 1/2, or 1. This range is well suited to relax the tension between late and early-time Hubble determinations, and is within the reach of upcoming CMB experiments. The dark matter could also originate as Hawking radiation in a black hole dominated early universe, although such dark matter candidates must be very heavy ($m_{\mathrm{DM}}>10^{11}$ GeV) if they are to avoid exceeding the measured abundance.

    hep-phastro-ph.COJHEP(2019)·234 citations
11. 11*

    The Collinear Limit of the Energy-Energy Correlator

    Lance J. Dixon🇺🇸 · Ian Moult🇺🇸 · Hua Xing Zhu🇨🇳

    The energy-energy-correlator (EEC) observable in $e^{+}{e}^{-}$ annihilation measures the energy deposited in two detectors as a function of the angle between the detectors. The collinear limit, where the angle between the two detectors approaches zero, is of particular interest for describing the substructure of jets produced at hadron colliders as well as in $e^{+}{e}^{-}$ annihilation. We derive a factorization formula for the leading power asymptotic behavior in the collinear limit of a generic quantum field theory, which allows for the resummation of logarithmically enhanced terms to all orders by renormalization group evolution. The relevant anomalous dimensions are expressed in terms of the timelike data of the theory, in particular the moments of the timelike splitting functions, which are known to high perturbative orders. We relate the small angle and back-to-back limits to each other via the total cross section and an integral over intermediate angles. This relation provides us with the initial conditions for quark and gluon jet functions at order ${\alpha }_s^2$. In QCD and in $\mathcal{N}=1$ super-Yang-Mills theory, we then perform the resummation to next-to-next-to-leading logarithm, improving previous calculations by two perturbative orders. We highlight the important role played by the non-vanishing $\beta$ function in these theories, which while subdominant for Higgs decays to gluons, dominates the behavior of the EEC in the collinear limit for $e^{+}{e}^{-}$ annihilation, and in $\mathcal{N}=1$ super-Yang-Mills theory. In conformally invariant $\mathcal{N}=4$ super-Yang-Mills theory, reciprocity between timelike and spacelike evolution can be used to express our factorization formula as a power law with exponent equal to the spacelike twist-two spin-three anomalous dimensions, thus providing a connection between timelike and spacelike approaches.

    hep-phhep-thPRD(2019)·213 citations
12. 12*

    Prospects for Dark Boson at the LHC

    Himadri Roy🇮🇳

    Non-Abelian Vector Boson Dark Matter (VBDM), arising from an $SU(2{)}_N$ extension of the Standard Model (SM) has been studied. The Dark Matter (DM) is stabilized by imposing an additional discrete global symmetry $S^{{}^{\prime }}$ with charges, such that it satisfies $S=S^{{}^{\prime }}+T_{3N}$ even when $SU(2{)}_N$ is completely broken. This model, apart from a single-component DM also offers a two-component DM augmented by a scalar and a vector boson, which lives over a large parameter space evading strong direct search bounds. Apart from potential DM candidates, this model also explains the smallness of neutrino masses through the $inverse$ $seesaw$ $mechanism$. We have computed tree-unitarity bound to limit the scalar mass spectrum in our model. Phenomenological aspects of the model have been discussed. Further, we have analyzed the possible collider signatures at the Large Hadron Collider (LHC) and its future implications.

    hep-ph0 citations
13. 13*

    Screening without screening: baryon energy at high baryon density

    Jeff Greensite🇺🇸 · Evan Owen🇺🇸

    We compute the Coulomb interaction energy of dense sets of static quarks in a compact volume (much smaller than the lattice volume) containing one quark per lattice site. The quark color charges are combined into either a set of three-quark nucleon states, or into a non-factorizable "one big hadron" state. In both cases we find that the energy per quark is roughly constant as the volume of quarks increases. A surprise is that if we construct the nucleon states from sets of three quarks chosen at random in the volume, then the energy per quark remains roughly constant, even as the average distance between quarks in a nucleon state grows as the volume increases. This energy dependence of a nucleon in a dense medium is at odds with the behavior of an isolated nucleon as quark separation increases, and for static quarks it is not easily explicable in terms of some version of Debye screening.

    ↳ hep-lathep-phPRD(2019)·0 citations
14. 14*

    Effective repulsion in dense quark matter from non-perturbative gluon exchange

    Yifan Song🇺🇸 · Gordon Baym🇺🇸 · Tetsuo Hatsuda🇯🇵 · Toru Kojo🇨🇳

    A moderately strong vector repulsion between quarks in dense quark matter is needed to explain how a quark core can support neutron stars heavier than two solar masses. We study this repulsion, parametrized by a four-fermion interaction with coupling g_V, in terms of non-perturbative gluon exchange in QCD in the Landau gauge. Matching the energy of quark matter, g_V n_q^2 (where n_q is the number density of quarks) with the quark exchange energy calculated in QCD with a gluon propagator parametrized by a finite gluon mass m_g and a frozen coupling alpha_s, at moderate quark densities, we find that gluon masses m_g in the range 200 - 600 MeV and alpha_s = 2 - 4 lead to a g_V consistent with neutron star phenomenology. Estimating the effects of quark masses and a color-flavor-locked (CFL) pairing gap, we find that g_V can be well approximated by a flavor-symmetric, decreasing function of density. We briefly discuss similar matchings for the isovector repulsion and for the pairing attraction.

    ↳ astro-ph.HEhep-phnucl-thPRD(2019)·46 citations
15. 15*

    Linking multipole vectors and pseudoentropies for CMB analysis

    Marvin Pinkwart🇩🇪 · Peter Schupp🇩🇪 · Dominik J. Schwarz🇩🇪

    Multipole vectors and pseudoentropies provide powerful tools for a numerically fast and vivid investigation of possible statistically anisotropic, respectively non-Gaussian signs in CMB temperature fluctuations. After reviewing and linking these two conceptions we compare their application to data analysis using the Planck 2015 NILC full sky map.

    ↳ astro-ph.COhep-phquant-ph0 citations
16. 16*

    Dark matter from scalar field fluctuations

    Tommi Tenkanen🇺🇸

    Dark matter (DM) may have its origin in a pre-Big Bang epoch, the cosmic inflation. Here, we consider for the first time a broad class of scenarios where a massive free scalar field unavoidably reaches an equilibrium between its classical and quantum dynamics in a characteristic time scale during inflation and sources the DM density. The study gives the abundance and perturbation spectrum of any DM component sourced by the scalar field. We show that this class of scenarios generically predicts enhanced structure formation, allowing one to test models where DM interacts with matter only gravitationally.

    ↳ astro-ph.COgr-qchep-phPRL(2019)·72 citations
17. 17*

    Nucleon isovector charges and twist-2 matrix elements with $N_f=2+1$ dynamical Wilson quarks

    Tim Harris🇩🇪 · Georg von Hippel🇩🇪 · Parikshit Junnarkar🇮🇳 · Harvey B. Meyer🇩🇪 · Konstantin Ottnad🇩🇪 · Jonas Wilhelm🇩🇪 · Hartmut Wittig🇩🇪 · Linus Wrang🇩🇪

    We present results from a lattice QCD study of nucleon matrix elements at vanishing momentum transfer for local and twist-2 isovector operator insertions. Computations are performed on gauge ensembles with non-perturbatively improved $N_f=2+1$ Wilson fermions, covering four values of the lattice spacing and pion masses down to $M_{\pi }\approx 200$MeV. Several source-sink separations (typically ~1.0fm to ~1.5fm) allow us to assess excited-state contamination. Results on individual ensembles are obtained from simultaneous two-state fits across all observables and all available source-sink separations with the energy gap as a common fit parameter. Renormalization has been performed non-perturbatively using the Rome-Southampton method for all but the finest lattice spacing for which an extrapolation has been used. Physical results are quoted in the $\overline{MS}$ scheme at a scale of $\mu =2$GeV and are obtained from a combined chiral, continuum and finite-size extrapolation. For the nucleon isovector axial, scalar and tensor charges we find physical values of $g_A^{u-d}=1.242(25{)}_{\text{stat}}(\genfrac{}{}{0ex}{}{+00}{-31}{)}_{\text{sys}}$, $g_S^{u-d}=1.13(11{)}_{\text{stat}}(\genfrac{}{}{0ex}{}{+07}{-06}{)}_{\text{sys}}$ and $g_T^{u-d}=0.965(38{)}_{\text{stat}}(\genfrac{}{}{0ex}{}{+13}{-41}{)}_{\text{sys}}$, respectively, where individual systematic errors in each direction from the chiral, continuum and finite-size extrapolation have been added in quadrature. Our final results for the isovector average quark momentum fraction and the isovector helicity and transversity moments are given by $⟨x{⟩}_{u-d}=0.180(25{)}_{\text{stat}}(\genfrac{}{}{0ex}{}{+14}{-06}{)}_{\text{sys}}$, $⟨x{⟩}_{\Delta u-\Delta d}=0.221(25{)}_{\text{stat}}(\genfrac{}{}{0ex}{}{+10}{-00}{)}_{\text{sys}}$ and $⟨x{⟩}_{\delta u-\delta d}=0.212(32{)}_{\text{stat}}(\genfrac{}{}{0ex}{}{+20}{-10}{)}_{\text{sys}}$, respectively.

    ↳ hep-lathep-phnucl-thPRD(2019)·93 citations
18. 18*

    The light-ray OPE and conformal colliders

    Murat Kologlu🇺🇸 · Petr Kravchuk🇨🇭 · David Simmons-Duffin🇺🇸 · Alexander Zhiboedov🇨🇭

    We derive a nonperturbative, convergent operator product expansion (OPE) for null-integrated operators on the same null plane in a CFT. The objects appearing in the expansion are light-ray operators, whose matrix elements can be computed by the generalized Lorentzian inversion formula. For example, a product of average null energy (ANEC) operators has an expansion in the light-ray operators that appear in the stress-tensor OPE. An important application is to collider event shapes. The light-ray OPE gives a nonperturbative expansion for event shapes in special functions that we call celestial blocks. As an example, we apply the celestial block expansion to energy-energy correlators in N=4 Super Yang-Mills theory. Using known OPE data, we find perfect agreement with previous results both at weak and strong coupling, and make new predictions at weak coupling through 4 loops (NNNLO).

    ↳ hep-thhep-phJHEP(2021)·221 citations
19. 19*

    A note on supergravity inflation in braneworld

    Mudassar Sabir🇨🇳 · Waqas Ahmed🇨🇳 · Yungui Gong🇨🇳 · Shan Hu🇨🇳 · Tianjun Li🇨🇳 · Lina Wu🇨🇳

    We discuss supergravity inflation in braneworld cosmology for the class of potentials $V(\varphi )=\alpha {\varphi }^n\exp (-{\beta }^{\mathrm{m}}{\varphi }^{\mathrm{m}})$ with $m=1,2$. These minimal SUGRA models evade the $\eta$ problem due to a broken shift symmetry and can easily accommodate the observational constraints. In the high energy regime $V/\lambda \gg 1$, the numerical predictions and approximate analytic formulas are given for the scalar spectral index $n_s$ and tensor-to-scalar ratio $r$. The models with smaller $n$ are preferred while the models with larger $n$ are out of the $2\sigma$ region. Remarkably, the ${\rho }^2/\lambda$ correction to the energy density in Friedmann equation results in sub-Planckian inflaton excursions $\Delta \varphi <1$.

    ↳ hep-thgr-qchep-phInt.J.Mod.Phys.A(2021)·10 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.