Wed·Apr 12, 2017Wednesday·April 12, 2017

1. 01*

   The Case for an EeV Gravitino

   Emilian Dudas🇫🇷 · Yann Mambrini🇫🇷 · Keith Olive🇺🇸

   We consider the possibility that supersymmetry is broken above the inflationary mass scale and that the only "low" energy remnant of supersymmetry is the gravitino with mass of order the EeV scale. The gravitino in this class of models becomes a candidate for the dark matter of the Universe. To avoid the over-production of gravitinos from the decays of the next-to-lightest supersymmetric particle we argue that the supersymmetric spectrum must lie above the inflationary mass scale ($M_{\mathrm{SUSY}}>10^{-5}{M}_{\mathrm{P}}\sim 10^{13}$ GeV). Since $m_{3/2}\simeq M_{\mathrm{SUSY}}^2/M_{\mathrm{P}}$, we expect $m_{3/2}\gtrsim 0.2$ EeV. Cosmological constraints then predict a relatively large reheating temperature between $10^{10}$ and $10^{12}$ GeV.

   hep-phastro-ph.HEhep-thPRL(2017)·97 citations
2. 02*

   Jet observables and stops at 100 TeV collider

   JiJi Fan🇺🇸 · Prerit Jaiswal🇺🇸 · John Shing Chau Leung🇺🇸

   A future proton-proton collider with center of mass energy around 100 TeV will have a remarkable capacity to discover massive new particles and continue exploring weak scale naturalness. In this work we will study its sensitivity to two stop simplified models as further examples of its potential power: pair production of stops that decay to tops or bottoms and higgsinos; and stops that are either pair produced or produced together with a gluino and then cascade down through gluinos to the lightest superpartner (LSP). In both simplified models, super-boosted tops or bottoms with transverse momentum of order TeV will be produced abundantly and call for new strategies to identify them. We will apply a set of simple jet observables, including track-based jet mass, N-subjettiness and mass drop, to tag the boosted hadronic or leptonic decaying objects and suppress the Standard Model as well as possible SUSY backgrounds. Assuming 10% systematic uncertainties, the future 100 TeV collider can discover (exclude) stops with masses up to 6 (7) TeV with 3 inverse attobarns of integrated luminosity if the stops decay to higgsinos. If the stops decay through gluinos to LSPs, due to additional SUSY backgrounds from gluino pair production, a higher luminosity of about 30 inverse attobarns is needed to discover stops up to 6 TeV. We will also discuss how to use jet observables to distinguish simplified models with different types of LSPs. The boosted top or bottom tagging strategies developed in this paper could also be used in other searches at a 100 TeV collider. For example, the strategy could help discover gluino pair production with gluino mass close to 11 TeV with 3 inverse attobarns of integrated luminosity.

   hep-phPRD(2017)·7 citations
3. 03*

   3-D Glasma initial state from small-x evolution

   Björn Schenke🇺🇸 · Sören Schlichting🇺🇸

   We present an ab-initio approach to compute the longitudinal dependence of the initial state in heavy-ion collisions by including small-x evolution of the nuclear gluon distributions. Extending the IP-Glasma model by including JIMWLK rapidity evolution, we compute event-by-event rapidity distributions of produced gluons and the early time energy momentum tensor as a function of space-time rapidity and transverse coordinates. We show how the effects of small-x evolution manifest themselves in longitudinal (rapidity) correlations of event-by-event multiplicities and transverse geometry and compare our results to various phenomenological models and experimental observations.

   hep-phnucl-thNPA(2017)·2 citations
4. 04*

   Gluon Spectrum in Quark-Gluon Plasma under Strong Magnetic Fields

   Koichi Hattori🇨🇳 · Daisuke Satow🇩🇪

   We obtain the general expression of the gluon propagator at finite temperature ($T$) and in a magnetic field ($B$), for the case that the four transverse tensor structures appear in the gluon self-energy. By using this expression and a specific form of the one-loop gluon self-energy in the lowest Landau level approximation, we analyze the gluon spectrum in the strong magnetic field limit. As a result, we find that there exist two collective excitations of which the energies are of the order of $p\sim gT$ with $g$ being the coupling constant. One of the two excitations enjoys properties quite different from those of the collective excitations at $B=0$ which have been discussed by using the hard thermal loop approximation. We also discuss the static and dynamical screening effects, which are expected to be important for computation of transport coefficients in strong magnetic fields.

   hep-phPRD(2018)·44 citations
5. 05*

   Froissart bound and self-similarity based models of proton structure functions

   D. K. Choudhury🇮🇳 · Baishali Saikia🇮🇳

   Froissart Bound implies that the total proton-proton cross-section (or equivalently structure function) cannot rise faster than the logarithmic growth ${\log }^{2}s\sim {\log }^{2}1/x$, where \textit{s} is the square of the center of mass energy and \textit{x} is the Bjorken variable. Compatibility of such behavior with the notion of self-similarity in a model of structure function suggested by us sometime back is now generalized to more recent improved self-similarity based models and compare with recent data as well as with the model of Block, Durand, Ha and McKay. Our analysis suggests that Froissart bound compatible self-similarity based models are possible with ${\log }^{2}1/x$ rise in limited $x-Q^2$ ranges of HERA data, but their phenomenological ranges validity are narrower than the corresponding models having power law rise in $1/x$.

   hep-phInt.J.Mod.Phys.A(2018)·2 citations
6. 06*

   Pion radiative weak decay from the instanton vacuum

   Sang-In Shim🇰🇷 · Hyun-Chul Kim🇰🇷

   We investigate the vector and axial-vector form factors for the pion radiative weak decays ${\pi }^{+}\to e^{+}{\nu }_e\gamma$ and ${\pi }^{+}\to e^{+}{\nu }_e{e}^{+}{e}^{-}$, based on the gauged effective chiral action from the instanton vacuum in the large $N_c$ limit. The nonlocal contributions, which arise from the gauging of the action, enhance the vector form factor by about $20\%$, whereas the axial-vector form factor is reduced by almost $30\%$. Both the results for the vector and axial-vector form factors at the zero momentum transfer are in good agreement with the experimental data. The dependence of the form factors on the momentum transfer is also studied. The slope parameters are computed and compared with other works.

   hep-phhep-exnucl-thPLB(2017)·5 citations
7. 07*

   Hollowness in pp scattering

   Wojciech Broniowski🇵🇱 · Enrique Ruiz Arriola🇪🇸

   It is argued that the hollowness effect (depletion in the absorptive part of the scattering cross section at small values of the impact parameter) in the proton-proton scattering at the the LHC energies finds its origin in the quantum nature of the process, resulting in large values of the real part of the eikonal phase. The effect cannot be reconciled with an incoherent superposition of the absorption from the proton constituents, thus suggests the change of this basic paradigm of high-energy scattering.

   hep-phhep-exActa Phys.Polon.B(2017)·11 citations
8. 08*

   Cosmic-ray fermion decay by emission of on-shell W bosons with CPT violation

   D. Colladay🇺🇸 · J. P. Noordmans🇵🇹 · R. Potting🇵🇹

   We study CPT and Lorentz violation in the electroweak gauge sector of the Standard Model in the context of the Standard-Model Extension. In particular, we consider the Lorentz-violating and CPT-odd Chern-Simons like parameter for the W boson, which is thus far unbounded by experiment. We demonstrate that any non-zero value of this parameter implies that, for sufficiently large energies, one of the polarization modes of the W boson propagates with spacelike four-momentum. In this scenario, emission of W bosons by ultra-high-energy cosmic rays is possible. We calculate the induced fermion energy-loss rate and we deduce the first limit on the pertinent Lorentz- and CPT-violating parameter that couples to the W boson. Consistency between the quantum description in various reference frames is preserved by using a recently formulated covariant quantization procedure for massive photons and applying it to the W bosons.

   hep-phPRD(2017)·17 citations
9. 09*

   Associated $t\bar{t}H$ production at the LHC: theoretical predictions at NLO+NNLL accuracy

   Anna Kulesza🇩🇪 · Leszek Motyka🇵🇱 · Tomasz Stebel🇵🇱 · Vincent Theeuwes🇺🇸

   We perform threshold resummation of soft gluon corrections to the total cross section and the invariant mass distribution for the process $pp\to t\bar{t}H$. The resummation is carried out at next-to-next-to-leading-logarithmic (NNLL) accuracy using the direct QCD Mellin space technique in the three-particle invariant mass kinematics. After presenting analytical expressions we discuss the impact of resummation on the numerical predictions for the associated Higgs boson production with top quarks at the LHC. We find that NLO+NNLL resummation leads to predictions for which the central values are remarkably stable with respect to scale variation and for which theoretical uncertainties are reduced in comparison to NLO predictions.

   hep-phPRD(2018)·69 citations
10. 10*

    Dynamics of Electroweak Phase Transition In Singlet-Scalar Extension of the Standard Model

    Gowri Kurup🇺🇸 · Maxim Perelstein🇺🇸

    An addition to the Standard Model of a real, gauge-singlet scalar field, coupled via a Higgs portal interaction, can reopen the possibility of a strongly first-order electroweak phase transition (EWPT) and successful electroweak baryogenesis (EWBG). If a discrete symmetry that forbids doublet-singlet mixing is present, this model is notoriously difficult to test at the Large Hadron Collider. As a result, it emerged as a useful benchmark for evaluating the capabilities of proposed future colliders to conclusively test EWPT and EWBG. In this paper, we evaluate the bubble nucleation temperature throughout the parameter space of this model where a first-order transition is expected. We find that in large parts of this parameter space, bubbles in fact do not nucleate at any finite temperature, eliminating these models as viable EWBG scenarios. This constraint eliminates most of the region where a "two-step" phase transition is naively predicted, while the "one-step" transition region is largely unaffected. In addition, expanding bubble walls must not reach relativistic speeds during the transition for baryon asymmetry to be generated. We show that this condition further reduces the parameter space with viable EWBG.

    hep-phPRD(2017)·158 citations
11. 11*

    Loop suppressed light fermion masses with $U(1{)}_R$ gauge symmetry

    Takaaki Nomura🇰🇷 · Hiroshi Okada🇹🇼

    We propose a model with two Higgs doublet where quark and charged-lepton masses in the first and second families are induced at one-loop level, and neutrino masses are induced at the two-loop level. In our model we introduce an extra $U(1{)}_R$ gauge symmetry that plays a crucial role in achieving desired terms in no conflict with anomaly cancellation. We show the mechanism to generate fermion masses, the resultant mass matrices and Yukawa interactions in mass eigenstates, and discuss several interesting phenomenologies such as muon anomalous magnetic dipole moment and dark matter candidate that are arisen from this model.

    hep-phPRD(2017)·27 citations
12. 12*

    Higgs boson mass corrections in the $\mu \nu$SSM with effective potential methods

    Hai-Bin Zhang🇨🇳 · Tai-Fu Feng🇨🇳 · Xiu-Yi Yang🇨🇳 · Shu-Min Zhao🇨🇳 · Guo-Zhu Ning🇨🇳

    To solve the $\mu$ problem of the MSSM, the $\mu$ from $\nu$ Supersymmetric Standard Model ($\mu \nu$SSM) introduces three singlet right-handed neutrino superfields ${\hat{\nu }}_i^c$, which lead to the mixing of the neutral components of the Higgs doublets with the sneutrinos, producing a relatively large CP-even neutral scalar mass matrix. In this work, we analytically diagonalize the CP-even neutral scalar mass matrix and analyze in detail how the mixing impacts the lightest Higgs boson mass. We also give an approximate expression for the lightest Higgs boson mass. Simultaneously, we consider the radiative corrections to the Higgs boson masses with effective potential methods.

    hep-phPRD(2017)·7 citations
13. 13*

    Colorful Twisted Top Partners and Partnerium at the LHC

    Yevgeny Kats🇮🇱 · Matthew McCullough🇨🇭 · Gilad Perez🇮🇱 · Yotam Soreq🇺🇸 · Jesse Thaler🇺🇸

    In scenarios that stabilize the electroweak scale, the top quark is typically accompanied by partner particles. In this work, we demonstrate how extended stabilizing symmetries can yield scalar or fermionic top partners that transform as ordinary color triplets but carry exotic electric charges. We refer to these scenarios as "hypertwisted" since they involve modifications to hypercharge in the top sector. As proofs of principle, we construct two hypertwisted scenarios: a supersymmetric construction with spin-0 top partners, and a composite Higgs construction with spin-1/2 top partners. In both cases, the top partners are still phenomenologically compatible with the mass range motivated by weak-scale naturalness. The phenomenology of hypertwisted scenarios is diverse, since the lifetimes and decay modes of the top partners are model dependent. The novel coupling structure opens up search channels that do not typically arise in top-partner scenarios, such as pair production of top-plus-jet resonances. Furthermore, hypertwisted top partners are typically sufficiently long lived to form "top-partnerium" bound states that decay predominantly via annihilation, motivating searches for rare narrow resonances with diboson decay modes.

    hep-phJHEP(2017)·16 citations
14. 14*

    Magnetic field instability driven by anomalous magnetic moments of massive fermions and electroweak interaction with background matter

    Maxim Dvornikov (IZMIRAN, Tomsk State University)🇷🇺

    It is shown that the electric current of massive fermions along the external magnetic field can be excited in the case when particles possess anomalous magnetic moments and electroweakly interact with background matter. This current is calculated on the basis of the exact solution of the Dirac equation in the external fields. It is shown that the magnetic field becomes unstable if this current is taken into account in the Maxwell equations. Considering a particular case of a degenerate electron gas, which can be found in a neutron star, it is revealed that the seed magnetic field can be significantly enhanced. The application of the results to astrophysics is also discussed.

    hep-phastro-ph.HEJETP Lett.(2017)·4 citations
15. 15*

    Heavy Baryons and their Exotics from Instantons in Holographic QCD

    Yizhuang Liu🇺🇸 · Ismail Zahed🇺🇸

    We use a variant of the $D4$-$D8$ construction that includes two chiral and one heavy meson, to describe heavy-light baryons and their exotics as heavy mesons bound to a flavor instanton in bulk. At strong coupling, the heavy meson is shown to {\it always bind} in the form of a flavor instanton zero mode in the fundamental representation. The ensuing instanton moduli for the heavy baryons exhibits both chiral and heavy quark symmetry. We detail how to quantize it, and derive model independent mass relations for heavy bayons with a single-heavy quark in leading order, in overall agreement with the reported baryonic spectra with one charm or bottom. We also discuss the low-lying masses and quantum assignments for the even and odd parity states, some of which are yet to be observed. We extend our analysis to double-heavy pentaquarks with hidden charm and bottom. In leading order, we find a pair of doube-heavy iso-doublets with $I{J}^{\pi }=\frac{1}{2}{\frac{1}{2}}^{-},\frac{1}{2}{\frac{3}{2}}^{-}$ assignments for all heavy flavor combinations. We also find five new Delta-like pentaquark states with $I{J}^{\pi }=\frac{3}{2}{\frac{1}{2}}^{-},\frac{3}{2}{\frac{3}{2}}^{-},\frac{3}{2}{\frac{5}{2}}^{-}$ assignments for both charm and bottom.

    hep-phhep-thPRD(2017)·39 citations
16. 16*

    Singlet-Doublet Fermionic Dark Matter, Neutrino Mass and Collider Signatures

    Subhaditya Bhattacharya🇮🇳 · Nirakar Sahoo🇮🇳 · Narendra Sahu🇮🇳

    We propose a minimal extension of the standard model (SM) by including a scalar triplet with hypercharge 2 and two vector-like leptons: one doublet and a singlet, to explain simulatenously the non-zero neutrino mass and dark matter (DM) content of the Universe. The DM emerges out as a mixture of the neutral component of vector-like lepton doublet and singlet, being odd under a discrete $Z_2$ symmetry. After electroweak symmetry breaking the triplet scalar gets an induced vev, which give Majorana masses not only to the light neutrinos but also to the DM. Due to the Majorana mass of DM, the $Z$ mediated elastic scattering with nucleon is forbidden. However, the Higgs mediated direct detection cross-section of the DM gives an excellent opportunity to probe it at Xenon-1T. The DM can not be detected at collider. However, the charged partner of the DM (often next-to-lightest stable particle) can give large dispalced vertex signature at the Large Hadron Collider (LHC).

    hep-phPRD(2017)·54 citations
17. 17*

    Explanation of the 17 MeV Atomki Anomaly in a $U(1{)}^{\prime }$-Extended 2-Higgs Doublet Model

    Luigi Delle Rose🇬🇧 · Shaaban Khalil🇪🇬 · Stefano Moretti🇬🇧

    Motivated by an anomaly observed in the decay of an excited state of Beryllium by the Atomki collaboration, we study an extension of the Standard Model with a gauged $U(1{)}^{\prime }$ symmetry in presence of a 2-Higgs Doublet Model structure of the Higgs sector. We show that this scenario complies with a variety of experimental results and is able to explain the potential presence of a resonant spin-1 gauge boson, $Z^{\prime }$, with a mass of 17 MeV in the Atomki experimental data, for appropriate choices of $U(1{)}^{\prime }$ charges and Yukawa interactions.

    hep-phPRD(2017)·80 citations
18. 18*

    Are the new excited ${\Omega }_c$ baryons negative parity states?

    T.M.Aliev🇹🇷 · S.Bilmis🇹🇷 · M.Savci🇹🇷

    We calculate the mass and residue of the newly observed ${\Omega }_c(3000)$ and ${\Omega }_c(3066)$ states with quantum numbers $J^P={\frac{1}{2}}^{-}$ and ${\frac{3}{2}}^{-}$ within QCD sum rules. Our predictions on masses are in good agreement with the experimental results.

    hep-phMod.Phys.Lett.A(2020)·35 citations
19. 19*

    Higgsplosion: Solving the Hierarchy Problem via rapid decays of heavy states into multiple Higgs bosons

    Valentin V. Khoze🇬🇧 · Michael Spannowsky🇬🇧

    We introduce and discuss two inter-related mechanisms operative in the electroweak sector of the Standard Model at high energies. Higgsplosion, the first mechanism, occurs at some critical energy in the 25 to 10^3 TeV range, and leads to an exponentially growing decay rate of highly energetic particles into multiple Higgs bosons. We argue that this a well-controlled non-perturbative phenomenon in the Higgs-sector which involves the final state Higgs multiplicities n in the regime n \lambda >> 1 where \lambda is the Higgs self-coupling. If this mechanism is realised in nature, the cross-sections for producing ultra-high multiplicities of Higgs bosons are likely to become observable and even dominant in this energy range. At the same time, however, the apparent exponential growth of these cross-sections at even higher energies will be tamed and automatically cut-off by a related Higgspersion mechanism. As a result, and in contrast to previous studies, multi-Higgs production does not violate perturbative unitarity. Building on this approach, we then argue that the effects of Higgsplosion alter quantum corrections from very heavy states to the Higgs boson mass. Above a certain energy, which is much smaller than their masses, these states would rapidly decay into multiple Higgs bosons. The heavy states become unrealised as they decay much faster than they are formed. The loop integrals contributing to the Higgs mass will be cut off not by the masses of the heavy states, but by the characteristic loop momenta where their decay widths become comparable to their masses. Hence, the cut-off scale would be many orders of magnitude lower than the heavy mass scales themselves, thus suppressing their quantum corrections to the Higgs boson mass.

    hep-phhep-thNPB(2018)·56 citations
20. 20*

    Effects of enhanced bulk viscosity near the QCD critical point

    Akihiko Monnai🇫🇷 · Swagato Mukherjee🇺🇸 · Yi Yin🇺🇸

    Search for the conjectured QCD critical point is one of the major scientific goals for the Beam Energy Scan program at RHIC. The growth of the correlation length is a universal feature for systems near criticality, and bulk viscosity exhibits the strongest dependence on the correlation length. We investigate its effects using a relativistic hydrodynamic model to find that rapidity distributions of charged particles and net baryon number are visibly modified if the fireball passes through the vicinity of the QCD critical point on the phase diagram. We also discuss how critical modification of dilepton emission rate may leave imprints on invariant mass spectra.

    ↳ nucl-thhep-phnucl-exNPA(2017)·6 citations
21. 21*

    RG scaling relations at chiral phase transition in two-flavor QCD

    K.-I. Ishikawa🇯🇵 · Y. Iwasaki🇯🇵 · Yu Nakayama🇯🇵 · T. Yoshie🇯🇵

    We investigate the nature of the chiral phase transition in the massless two-flavor QCD using the renormalization group improved gauge action and the Wilson quark action on $32^3\times 16$, $24^3\times 12$, and $16^3\times 8$ lattices. Based on the renormalization group equation, we derive the scaling relation for the effective masses of mesons at the chiral phase transition point. If the chiral phase transition is second order, the effective masses as a function of the rescaled time/space do not depend on the lattice size and show the universal behavior. We find that our numerical simulations on the three sizes of lattices are excellently on the scaling curves, which is consistent with the second order phase transition.

    ↳ hep-lathep-phhep-th2 citations
22. 22*

    Investigation into the limits of perturbation theory at low Q^2 using HERA deep inelastic scattering data

    I. Abt🇩🇪 · A.M. Cooper-Sarkar🇬🇧 · B. Foster🇬🇧 · V. Myronenko🇩🇪 · K. Wichmann🇩🇪 · M. Wing🇬🇧

    A phenomenological study of the final combined HERA data on inclusive deep inelastic scattering (DIS) has been performed. The data are presented and investigated for a kinematic range extending from values of the four-momentum transfer, $Q^2$, above 10${}^4$ GeV${}^2$ down to the lowest values observable at HERA of $Q^2$ = 0.045 GeV${}^2$ and Bjorken $x$, $x_{\mathrm{Bj}}$ = 6 $\cdot$ 10${}^{-7}$. The data are well described by fits based on perturbative quantum chromodynamics (QCD) using collinear factorisation and evolution of the parton densities encompassed in the DGLAP formalism from the highest $Q^2$ down to $Q^2$ of a few GeV${}^2$. The Regge formalism can describe the data up to $Q^2\approx$ 0.65 GeV${}^2$. The complete data set can be described by a new fit using the ALLM parameterisation. The region between the Regge and the perturbative QCD regimes is of particular interest.

    ↳ hep-exhep-phPRD(2017)·24 citations
23. 23*

    Investigating the "kink" plot as a signal of the onset of deconfinement

    Michał Naskręt🇵🇱

    One of the physics goals of the NA61/SHINE collaboration at the CERN Super Proton Synchrotron is to study the phase diagram of hadronic matter. To this end, a series of heavy ion collision measurements are performed. It is believed that above a certain collision energy and system size a phase transition between hadronic matter and quark-gluon plasma occurs. A number of observables has been developed to determine which of the phases was created at the early stage of the collision. This report discusses the dependence of the ratio of the mean number of produced pions to the mean number of wounded nucleons on the Fermi energy measure. For comparison with other measurements this is often presented in the form of the the "kink" plot. This plot is presented enriched with preliminary results for Ar+Sc central collisions at 13A, 19A, 30A, 40A, 75A and 150A GeV/c beam momentum. The results are finally compared to data from other experiments.

    ↳ hep-exhep-phLith.J.Phys.(2017)·1 citation
24. 24*

    More on Polyakov Loops in the Deconfined Phase and Gauge/String Duality

    Oleg Andreev🇷🇺

    We consider a multi-string configuration that provides a new way to compute the expectation value of the Polyakov loop in a five-dimensional framework known as AdS/QCD. The obtained results are in reasonably good agreement with those obtained by lattice simulations for pure SU(3) gauge theory and also by the usual single string configuration.

    ↳ hep-thhep-lathep-phPRD(2017)·2 citations
25. 25*

    Bayesian truncation errors in chiral effective field theory: nucleon-nucleon observables

    J.A. Melendez🇺🇸 · S. Wesolowski🇺🇸 · R.J. Furnstahl🇺🇸

    Chiral effective field theory (EFT) predictions are necessarily truncated at some order in the EFT expansion, which induces an error that must be quantified for robust statistical comparisons to experiment. In previous work, a Bayesian model for truncation errors of perturbative expansions was adapted to EFTs. The model yields posterior probability distribution functions (pdfs) for these errors based on expectations of naturalness encoded in Bayesian priors and the observed order-by-order convergence pattern of the EFT. A first application was made to chiral EFT for neutron-proton scattering using the semi-local potentials of Epelbaum, Krebs, and Meißner (EKM). Here we extend this application to consider a larger set of regulator parameters, energies, and observables as a general example of a statistical approach to truncation errors. The Bayesian approach allows for statistical validations of the assumptions and enables the calculation of posterior pdfs for the EFT breakdown scale. The statistical model is validated for EKM potentials whose convergence behavior is not distorted by regulator artifacts. For these cases, the posterior for the breakdown scale is consistent with EKM assumptions.

    ↳ nucl-thhep-phnucl-exphysics.data-anPRC(2017)·190 citations
26. 26*

    Baryons still trace dark matter: probing CMB lensing maps for hidden isocurvature

    Tristan L. Smith🇺🇸 · Julian B. Muñoz🇺🇸 · Rhiannon Smith🇺🇸 · Kyle Yee🇺🇸 · Daniel Grin🇺🇸

    Compensated isocurvature perturbations (CIPs) are primordial fluctuations that balance baryon and dark-matter isocurvature to leave the total matter density unperturbed. The effects of CIPs on the cosmic microwave background (CMB) anisotropies are similar to those produced by weak lensing of the CMB: smoothing of the power spectrum, and generation of non-Gaussian features. Previous work considered the CIP effects on the CMB power-spectrum but neglected to include the CIP effects on estimates of the lensing potential power spectrum (though its contribution to the non-Gaussian, connected, part of the CMB trispectrum). Here, the CIP contribution to the standard estimator for the lensing potential power-spectrum is derived, and along with the CIP contributions to the CMB power-spectrum, Planck data is used to place limits on the root-mean-square CIP fluctuations on CMB scales, ${\Delta }_{\mathrm{rms}}^2(R_{\mathrm{CMB}})$. The resulting constraint of ${\Delta }_{\mathrm{rms}}^2(R_{\mathrm{CMB}})<4.3\times 10^{-3}$ using this new technique improves on past work by a factor of $\sim 3$. We find that for Planck data our constraints almost reach the sensitivity of the optimal CIP estimator. The method presented here is currently the most sensitive probe of the amplitude of a scale-invariant CIP power spectrum placing an upper limit of $A_{\mathrm{CIP}}<0.017$ at 95% CL. Future measurements of the large-scale CMB lensing potential power spectrum could probe CIP amplitudes as low as ${\Delta }_{\mathrm{rms}}^2(R_{\mathrm{CMB}})=8\times 10^{-5}$ ($A_{\mathrm{CIP}}=3.2\times 10^{-4}$).

    ↳ astro-ph.COhep-phPRD(2017)·27 citations
27. 27*

    PBH dark matter from axion inflation

    Valerie Domcke🇫🇷 · Francesco Muia🇬🇧 · Mauro Pieroni🇫🇷 · Lukas T. Witkowski🇫🇷

    Protected by an approximate shift symmetry, axions are well motivated candidates for driving cosmic inflation. Their generic coupling to the Chern-Simons term of any gauge theory gives rise to a wide range of potentially observable signatures, including equilateral non-Gaussianites in the CMB, chiral gravitational waves in the range of direct gravitational wave detectors and primordial black holes (PBHs). In this paper we revisit these predictions for axion inflation models non-minimally coupled to gravity. Contrary to the case of minimally coupled models which typically predict scale-invariant mass distributions for the generated PBHs at small scales, we demonstrate how broadly peaked PBH spectra naturally arises in this setup. For specific parameter values, all of dark matter can be accounted for by PBHs.

    ↳ astro-ph.COhep-phhep-thJCAP(2017)·116 citations
28. 28*

    Directional dark matter detection sensitivity of a two-phase liquid argon detector

    M. Cadeddu · M. Lissia · P. Agnes · G. Batignani · W. M. Bonivento · B. Bottino · M. Caravati · A. Cocco · G. Covone · A. de Candia · S. Catalanotti · V. Cataudella and 29 other authors

    We examine the sensitivity of a large scale two-phase liquid argon detector to the directionality of the dark matter signal. This study was performed under the assumption that, above 50 keV of recoil energy, one can determine (with some resolution) the direction of the recoil nucleus without head-tail discrimination, as suggested by past studies that proposed to exploit the dependence of columnar recombination on the angle between the recoil nucleus direction and the electric field. In this paper we study the differential interaction recoil rate as a function of the recoil direction angle with respect to the zenith for a detector located at the Laboratori Nazionali del Gran Sasso and we determine its diurnal and seasonal modulation. Using a likelihood-ratio based approach we show that, with the angular information alone, 100 events are enough to reject the isotropic hypothesis at three standard deviation level. For an exposure of 100 tonne years this would correspond to a spin independent WIMP-nucleon cross section of about 10^-46 cm^2 at 200 GeV WIMP mass. The results presented in this paper provide strong motivation for the experimental determination of directional recoil effects in two-phase liquid argon detectors.

    ↳ astro-ph.COhep-phphysics.ins-detJCAP(2019)·23 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.