Wed·May 9, 2018Wednesday·May 9, 2018

1. 01*

   The EDGES signal: An imprint from the mirror world?

   D. Aristizabal Sierra🇨🇱 · Chee Sheng Fong🇧🇷

   Recent results from the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) show an anomalous spectral feature at redshifts $z\sim 15-20$ in its 21-cm absorption signal. This deviation from cosmological predictions can be understood as a consequence of physics that either lower the hydrogen spin temperature or increases the radiation temperature through the injection of soft photons in the bath. In the latter case, standard model neutrino decays ${\nu }_i\to {\nu }_j\gamma$ induced by effective magnetic and electric transition moments (${\mu }_{\text{eff}}$) are precluded by the tight astrophysical constraints on ${\mu }_{\text{eff}}$. We show that if mirror neutrinos are present in the bath at early times, an analogous mechanism in the mirror sector can lead to a population of mirror photons that are then "processed" into visible photons through resonant conversion, thus accounting for the EDGES signal. We point out that the mechanism can work for mirror neutrinos which are either heavier than or degenerate with the standard model (SM) neutrinos, a scenario naturally realized in mirror twin Higgs models.

   hep-phPLB(2018)·22 citations
2. 02*

   Particle multiplicities in the central region of high-energy collisions from $k_T$-factorization with running coupling corrections

   Adrian Dumitru🇺🇸 · Andre V. Giannini🇧🇷 · Matthew Luzum🇧🇷 · Yasushi Nara🇯🇵

   Horowitz and Kovchegov have derived a $k_T$-factorization formula for particle production at small $x$ which includes running coupling corrections. We perform a first numerical analysis to confront the theory with data on the energy and centrality dependence of particle multiplicities at midrapidity in high-energy p+A (and A+A) collisions. Moreover, we point out a strikingly different dependence of the multiplicity per participant on $N_{\text{part}}$ in p+Pb vs.\ Pb+Pb collisions at LHC energies, and argue that the observed behavior follows rather naturally from the convolution of the gluon distributions of an asymmetric vs. symmetric projectile and target.

   hep-phnucl-thPLB(2018)·13 citations
3. 03*

   Constraints on a Light Leptophobic Mediator from LEP Data

   Manuel Drees🇩🇪 · Zhongyi Zhang🇩🇪

   We apply data taken at the $e^{+}{e}^{-}$ collider LEP in the 1990's at center-of-mass energy up to 209 GeV to constrain Dark Matter models with a light leptophobic spin-1 mediator $R$. We assume that the dark sector particle (DSP) is a spin-1/2 fermion $\chi$. This scenario is well studied in the context of LHC searches for mediator mass from 100 GeV to several TeV. Emission of the mediator off a quark or antiquark at LEP gives rise to di-jet plus missing energy and 4-jet signatures, which we use to limit the relevant couplings. We focus on scenarios with $2m_{\chi }>m_R$, which are poorly constrained by LHC data. We recast published searches by the ALEPH collaboration. For $m_{\chi }<20$ GeV the best bounds result from an analysis at $\sqrt{s}\simeq M_Z$ of di-jet plus missing energy events. For heavier DSP but $m_R<70$ GeV meaningful bounds can be derived from a four jet analysis at $\sqrt{s}=183$ GeV. Unfortunately published searches using four jet final states at $\sqrt{s}\simeq M_Z$ use only a small fraction of the total data sample. Moreover, all published searches for di-jet plus missing energy final states at $\sqrt{s}\ge 130$ GeV have poor efficiency for our model; we therefore design new cuts that combine good background rejection with higher efficiency. Re-analyzing the higher energy data using our new cuts, and an analysis of the complete four jet data sample taken at $\sqrt{s}\simeq M_Z$, can explore new regions of parameter space.

   hep-phhep-exJHEP(2018)·3 citations
4. 04*

   BaryoGEN, a Monte Carlo Generator for Sphaleron-Like Transitions in Proton-Proton Collisions

   Cameron Bravo🇺🇸 · Jay Hauser🇺🇸

   Sphaleron and instanton solutions of the Standard Model provide violation of baryon and lepton numbers and could lead to spectacular events at the LHC or future colliders. Certain models of new physics can also lead to sphaleron-like vacuum transitions. This nonperturbative physics could be relevant to the generation of the matter-antimatter asymmetry of the universe. We have developed BaryoGEN, an event generator that facilitates the exploration of sphaleron-like transitions in proton-proton collisions with minimal assumptions. BaryoGEN outputs standard Les Houches Event files that can be processed by PYTHIA, and the code is publicly available. We also discuss various approaches to experimental searches for such transitions in proton-proton collisions.

   hep-phJHEP(2018)·7 citations
5. 05*

   Muon $g-2$ and Dark Matter in the MSSM

   Peter Cox🇯🇵 · Chengcheng Han🇯🇵 · Tsutomu T. Yanagida🇯🇵

   We investigate the possibility that both dark matter and the long-standing discrepancy in the anomalous magnetic moment of the muon may be explained within the MSSM. In light of the stringent bounds from direct detection, we argue that the most promising viable scenarios have bino-like dark matter produced via either bino-wino or bino-slepton co-annihilation. We find that the combination of next-generation direct detection experiments and the LHC will be able to probe much of the interesting parameter space, however a future high-energy collider is needed to comprehensively explore this scenario.

   hep-phPRD(2018)·52 citations
6. 06*

   Rapidity gap distribution in diffractive deep-inelastic scattering and parton genealogy

   A.H. Mueller🇺🇸 · S. Munier🇫🇷

   We propose a partonic picture for high-mass diffractive dissociation events in onium-nucleus scattering, which leads to simple and robust predictions for the distribution of the sizes of gaps in diffractive dissociation of virtual photons off nuclei at very high energies. We show that the obtained probability distribution can formally be identified to the distribution of the decay time of the most recent common ancestor of a set of objects generated near the edge of a branching random walk, and explain the physical origin of this appealing correspondence. We then use the fact that the diffractive cross section conditioned to a minimum rapidity gap size obeys a set of Balitsky-Kovchegov equations in order to test numerically our analytical predictions. Furthermore, we show how simulations in the framework of a Monte Carlo implementation of the QCD evolution support our picture.

   hep-phPRD(2018)·18 citations
7. 07*

   Towards the minimal seesaw model for the prediction of neutrino CP violation

   Yusuke Shimizu🇯🇵 · Kenta Takagi🇯🇵 · Morimitsu Tanimoto🇯🇵

   We discuss the minimal seesaw model for the Dirac CP violating phase of the lepton mixing matrix. We introduce two right-handed Majorana neutrinos and obtain several textures of the tri-maximal lepton mixing matrices. Moreover, we discuss the observed baryon asymmetry of the universe through the leptogenesis mechanism. As the result, we obtain the specific model which predicts the negative sign of maximal Dirac CP violating phase and normal hierarchy of neutrino masses.

   hep-ph1 citation
8. 08*

   Probing transition form factors in the rare $B\to K^{\ast }\nu \bar{\nu }$ decay

   Mohammad Ahmady🇨🇦 · Alexandre Leger🇨🇦 · Zoe McIntyre🇨🇦 · Alexander Morrison🇨🇦 · Ruben Sandapen🇨🇦

   We compare the Standard Model (SM) predictions for the differential branching ratio of the rare $B\to K^{\ast }\nu \bar{\nu }$ decays using $B\to K^{\ast }$ form factors obtained from holographic light-front QCD (hLFQCD) and Sum Rules (SR) Distribution Amplitudes. For the total branching ratio, we predict $\mathcal{B}\mathcal{R}(\text{process}{)}_{\mathrm{hLFQCD}}=(6.36_{-0.74}^{+0.59})\times 10^{-6}$ and $\mathcal{B}\mathcal{R}(\text{process}{)}_{\mathrm{SR}}=(8.14_{-0.17}^{+0.16})\times 10^{-6}$. More interestingly, we find that the two model predictions for the differential branching ratio are sufficiently different at low momentum transfer, so that future measurements at Belle II may be able to discriminate between them. We also confirm numerically that the $K^{\ast }$ longitudinal polarization fraction $F_L$ has little sensitivity to the non-perturbative form factors and is thus an excellent observable to probe New Physics signals. We predict $F_L=0.40_{-0.01}^{+0.02}(0.41\pm 0.01)$ using hLFQCD (SR).

   hep-phPRD(2018)·10 citations
9. 09*

   Measuring quark polarizations at ATLAS and CMS

   Yevgeny Kats🇮🇱

   Being able to measure the polarization of quarks produced in various processes at the LHC would be of fundamental significance. Measuring the polarizations of quarks produced in new physics processes, once discovered, can provide crucial information about the new physics Lagrangian. In a series of recent papers, we have investigated how quark polarization measurements can be done in practice. The polarizations of heavy quarks (b and c) are expected to be largely preserved in the lightest baryons they hadronize into, the Lambda_b and Lambda_c, respectively. Furthermore, it is known experimentally that s-quark polarization is preserved as well, in Lambda baryons. We study how ATLAS and CMS can measure polarizations of b, c and s quarks using certain decays of these baryons. We propose to use the Standard Model ttbar and Wc samples to calibrate these measurements. We estimate that the Run 2 dataset will suffice for measuring the quark polarizations in these Standard Model samples with precisions of order 10%. We also propose various additional measurements for the near and far future that would help characterize the polarization transfer from the quarks to the baryons.

   hep-phhep-exFrascati Phys.Ser.(2017)·1 citation
10. 10*

    Reanalysis of ${\Omega }_c\to {\Xi }_c^{+}{K}^{-}$ decay in QCD

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

    The strong coupling constants of newly observed ${\Omega }_c^0$ baryons with spin $J=\frac{1}{2}$ and $J=\frac{3}{2}$ decaying into ${\Xi }_c^{+}{K}^{-}$ are estimated within light cone QCD sum rules. The calculations are performed within two different scenarios on quantum numbers of ${\Omega }_c$ baryons: a) all newly observed ${\Omega }_c$ baryons are negative parity baryons, i.e., the ${\Omega }_c(3000)$, ${\Omega }_c(3050)$, ${\Omega }_c(3066)$, and ${\Omega }_c(3090)$ have quantum numbers $J^P={\frac{1}{2}}^{-}$ and $J^P={\frac{3}{2}}^{-}$ states respectively; b) the states ${\Omega }_c(3000)$ and ${\Omega }_c(3050)$ have quantum numbers $J^P={\frac{1}{2}}^{-}$ and $J^P={\frac{1}{2}}^{+}$, while the states ${\Omega }_c(3066)$ and ${\Omega }_c(3090)$ have the quantum numbers $J^P={\frac{3}{2}}^{-}$ and $J^P={\frac{3}{2}}^{+}$, respectively. By using the obtained results on the coupling constants, we calculate the decay widths of the corresponding decays. The results on decay widths are compared with the experimental data of LHC Collaboration. We found out that the predictions on decay widths within these scenarios are considerably different from the experimental data, i.e., both considered scenarios are ruled out.

    hep-phAdv.High Energy Phys.(2018)·7 citations
11. 11*

    Boer-Mulders effect in the unpolarized pion induced Drell-Yan process at COMPASS within TMD factorization

    Xiaoyu Wang🇨🇳 · Wenjuan Mao🇨🇳 · Zhun Lu🇨🇳

    We investigate the theoretical framework of the $\cos 2\varphi$ azimuthal asymmetry contributed by the coupling of two Boer-Mulders functions in the dilepton production unpolarized $\pi p$ Drell-Yan process by applying the transverse momentum dependent factorization at leading order. We adopt the model calculation results of the unpolarized distribution function $f_1$ and Boer-Mulders function $h_1^{\perp }$ of pion meson from the light-cone wave functions. We take into account the transverse momentum evolution effects for both the distribution functions of pion and proton by adopting the existed extraction of the nonperturbative Sudakov form factor for the pion and proton distribution functions. An approximate kernel is included to deal with the energy dependence of the Boer-Mulders function related twist-3 correlation function $T_{q,F}^{(\sigma )}(x,x)$ needed in the calculation. We numerically estimate the Boer-Mulders asymmetry ${\nu }_{BM}$ as the functions of $x_p$, $x_{\pi }$, $x_F$ and $q_T$ considering the kinematics at COMPASS Collaboration.

    hep-phhep-exEPJC(2018)·20 citations
12. 12*

    The large-Nc limit of borelized spectral sum rules and the slope of radial Regge trajectories

    S. S. Afonin🇷🇺 · T. D. Solomko🇷🇺

    We put forward a new phenomenological method for calculating the slope of radial trajectories from values of ground states and vacuum condensates. The method is based on a large-$N_c$ extension of borelized spectral sum rules. The approach is applied to the light non-strange vector, axial, and scalar mesons. The extracted values of slopes proved to be approximately universal and are in the interval $1.4\pm 0.1$ GeV${}^2$. As a by-product, the given method leads to prediction of the second radial trajectory with ground state mass lying near 0.6 GeV.

    hep-phInt.J.Mod.Phys.A(2018)·7 citations
13. 13*

    Modification of jet structure in high-multiplicity pp collisions due to multiple-parton interactions and observing a multiplicity-independent characteristic jet size

    Zoltán Varga🇭🇺 · Róbert Vértesi🇭🇺 · Gergely Gábor Barnaföldi🇭🇺

    We study the multiplicity dependence of jet structures in pp collisions using Monte Carlo event generators. We give predictions for multiplicity-differential jet structures and present evidence for a non-trivial jet shape dependence on charged hadron event multiplicity, that can be used as a sensitive tool to experimentally differentiate between equally well-preforming simulation tunes. We also propose a way to validate the presence and extent of effects such as multiple parton interactions (MPI) or color reconnection (CR), based on the detection of non-trivial jet shape modification in high-multiplicity events at high pT. Using multiplicity-dependent jet structure observables in various pT windows might also help understanding the interplay between jet particles and the underlying event (UE). We introduce a multiplicity-independent characteristic jet size measure, and use a simplistic model to aid its physical interpretation.

    hep-phAdv.High Energy Phys.(2019)·16 citations
14. 14*

    The gluon and charm content of the deuteron

    Stanley J. Brodsky🇺🇸 · Kelly Yu-Ju Chiu🇺🇸 · Jean-Philippe Lansberg🇫🇷 · Nodoka Yamanaka🇫🇷

    We evaluate the frame-independent gluon and charm parton-distribution functions (PDFs) of the deuteron utilizing light-front quantization and the impulse approximation. We use a nuclear wave function obtained from solving the nonrelativistic Schroedinger equation with the realistic Argonne v18 nuclear force, which we fold with the proton PDF. The predicted gluon distribution in the deuteron (per nucleon) is a few percent smaller than that of the proton in the domain x_{bj} = Q^2 / (2 p_N \cdot q) \sim 0.4, whereas it is strongly enhanced for x_{bj} larger than 0.6. We discuss the applicability of our analysis and comment on how to extend it to the kinematic limit x_{bj} \to 2. We also analyze the charm distribution of the deuteron within the same approach by considering both the perturbatively and non-perturbatively generated (intrinsic) charm contributions. In particular, we note that the intrinsic-charm content in the deuteron will be enhanced due to 6-quark "hidden-color" QCD configurations.

    hep-phhep-exnucl-exnucl-thPLB(2018)·23 citations
15. 15*

    Anatomy of $b\to c\tau \nu$ anomalies

    Aleksandr Azatov🇮🇹 · Debjyoti Bardhan🇮🇱 · Diptimoy Ghosh🇮🇹 · Francesco Sgarlata🇮🇹 · Elena Venturini🇮🇹

    In recent times, one of the strongest hints of Physics Beyond the Standard Model (BSM) has been the anomaly in the ratios $R_D$ and $R_{D^{\ast }}$ measured in the charged current decays of $B$-mesons. In this work, we perform a comprehensive analysis of these decay modes, first in a model independent way and subsequently, in the context of composite Higgs models. We discuss in depth as to how linearly realised $\mathrm{SU}(2{)}_{\mathrm{L}}\times \mathrm{U}(1{)}_{\mathrm{Y}}$ symmetry imposes severe constraint on the various scenarios because of correlations with other $\Delta F=1$ processes and $Z\tau \tau$ and $Z\nu \nu$ couplings. In the composite Higgs paradigm with partial compositeness, we show that, irrespective of the flavour structure of the composite sector, constraints from $\Delta F=2$ processes bring the compositeness scale down to $\sim 650$ GeV which is in tension with electroweak precision observables. In the presence of composite leptoquarks, the situation improves only marginally (a factor of $\sqrt{2}$ in the compositeness scale), thus making the new states soon discoverable by direct searches at the LHC. We also comment on the possible explanation of the $R_{K,K^{\ast }}$ anomalies within the composite Higgs framework.

    hep-phhep-exJHEP(2018)·86 citations
16. 16*

    Higgs Mechanism in Nonlocal Field Theories

    Manami Noumi Hashi🇯🇵 · Hiroshi Isono🇹🇭 · Toshifumi Noumi🇯🇵 · Gary Shiu🇺🇸 · Pablo Soler🇩🇪

    We study spontaneous gauge symmetry breaking and the Higgs mechanism in nonlocal field theories. Motivated by the level truncated action of string field theory, we consider a class of nonlocal field theories with an exponential factor of the d'Alembertian attached to the kinetic and mass terms. Modifications of this kind are known to make mild the UV behavior of loop diagrams and thus have been studied not only in the context of string theory but also as an alternative approach to quantum gravity. In this paper we argue that such a nonlocal theory potentially includes a ghost mode near the nonlocal scale in the particle spectrum of the symmetry broken phase. This is in sharp contrast to local field theories and would be an obstruction to making a simple nonlocal model a UV complete theory. We then discuss a possible way out by studying nonlocal theories with extra symmetries such as gauge symmetries in higher spacetime dimensions.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2018)·22 citations
17. 17*

    Calculating charged particle observables using modified Wood Saxon model in HIJING for U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV

    S. K. Tripathy🇮🇳 · M. Younus🇮🇳 · Z. Naik🇮🇳 · P. K. Sahu🇮🇳

    We have implemented spherical harmonics in default Wood Saxon distribution of the HIJING model and calculated various physical observables such as transverse momentum, charged particle multiplicity, nuclear modification factor and particle ratios for charged particles at top RHIC energy with collisions of Uranium (U) nuclei. Results have been compared with available experimental data. We observe that, a particular type of collision configuration can produce significant magnitude change in observables. We have noticed that the tip-tip configuration shows higher magnitude of particle yield in central collisions, while the body-body configuration shows higher value in the cases of peripheral collisions, with the flip in the trend occurring for the mid-central U+U collisions. We observe that particle ratios are independent of configuration type.

    ↳ nucl-thhep-phNPA(2018)·5 citations
18. 18*

    Scheme-Independent Calculations of Anomalous Dimensions of Baryon Operators in Conformal Field Theories

    John A. Gracey🇬🇧 · Thomas A. Ryttov🇩🇰 · Robert Shrock🇺🇸

    We present the first analytic scheme-independent series calculations of anomalous dimensions of several types of baryon operators at an infrared fixed point (IRFP) in an asymptotically free SU(3) gauge theory with $N_f$ fermions. Separately, for an asymptotically free gauge theory with a gauge group $G$ and $N_f$ fermions in a representation $R$ of $G$, we consider physical quantities at an IRFP, including the anomalous dimension of gauge-invariant fermion bilinears and the derivative of the beta function. These quantities have been calculated in series expansions whose coefficients have been proved to be scheme-independent at each order. We illustrate the scheme independence using a variety of schemes, including the RI${}^{\prime }$ scheme and several types of momentum subtraction (MOM) schemes.

    ↳ hep-thhep-lathep-phPRD(2018)·24 citations
19. 19*

    Search for the Chiral Magnetic Effect in Relativistic Heavy-Ion Collisions

    Jie Zhao🇺🇸

    Relativistic heavy-ion collisions provide an ideal environment to study the emergent phenomena in quantum chromodynamics (QCD). The chiral magnetic effect (CME) is one of the most interesting, arising from the topological charge fluctuations of QCD vacua, immersed in a strong magnetic field. Since the first measurement nearly a decade ago of the possibly CME-induced charge correlation, extensive studies have been devoted to background contributions to those measurements. Many new ideas and techniques have been developed to reduce or eliminate the backgrounds. This article reviews these developments and the overall progress in the search for the CME.

    ↳ nucl-exhep-exhep-phnucl-thInt.J.Mod.Phys.A(2018)·29 citations
20. 20*

    Cosmological constraints on $\gamma$-gravity models

    Clara Álvarez Luna🇪🇸 · Spyros Basilakos🇬🇷 · Savvas Nesseris🇪🇸

    In this paper we place observational constraints on the well-known $\gamma$-gravity $f(R)$ model using the latest cosmological data, namely we use the latest growth rate, Cosmic Microwave Background, Baryon Acoustic Oscillations, Supernovae type Ia and Hubble parameter data. Performing a joint likelihood analysis we find that the $\gamma$-gravity model is in very good agreement with observations. Utilizing the AIC statistical test we statistically compare the current $f(R)$ model with $\Lambda$CDM cosmology and find that they are statistically equivalent. Therefore, $\gamma$-gravity can be seen as a useful scenario toward testing deviations from General Relativity. Finally, we note that we find somewhat higher values for the $f(R)$ best-fit values compared to those mentioned in the past in the literature and we argue that this could potential alleviate the halo-mass function problem.

    ↳ astro-ph.COgr-qchep-phPRD(2018)·14 citations
21. 21*

    Interplay between the holographic QCD phase diagram and entanglement entropy

    David Dudal🇧🇪 · Subhash Mahapatra🇮🇳

    In earlier work, we introduced a dynamical Einstein--Maxwell--dilaton model which mimics essential features of QCD (thermodynamics) below and above deconfinement. Although there are some subtle differences in the confining regime of our model as compared to the standard results, we do have a temperature dependent dual metric below $T_c$ as well, allowing for a richer and more realistic holographic modeling of the QCD phase structure. We now discuss how these features leave their imprints on the associated entanglement entropy when a strip region is introduced in the various phases. We uncover an even so rich structure in the entanglement entropy, consistent with the thermodynamical transitions, while again uncloaking some subtleties. Thanks to the temperature dependent confining geometry, we can present an original quantitative prediction for the phase diagram in terms of temperature and strip length, reporting a critical end point at the deconfinement temperature. We also generalize to the case with chemical potential.

    ↳ hep-thgr-qchep-lathep-phJHEP(2018)·82 citations
22. 22*

    Curvature of the pseudocritical line in QCD: Taylor expansion matches analytic continuation

    Claudio Bonati🇮🇹 · Massimo D'Elia🇮🇹 · Francesco Negro🇮🇹 · Francesco Sanfilippo🇮🇹 · Kevin Zambello🇮🇹

    We determine the curvature of the pseudo-critical line of $N_f=2+1$ QCD with physical quark masses via Taylor expansion in the quark chemical potentials. We adopt a discretization based on stout improved staggered fermions and the tree level Symanzik gauge action; the location of the pseudocritical temperature is based on chiral symmetry restoration. Simulations are performed on lattices with different temporal extent ($N_t=6,8,10$), leading to a continuum extrapolated curvature $\kappa =0.0145(25)$, which is in very good agreement with the continuum extrapolation obtained via analytic continuation and the same discretization, $\kappa =0.0135(20)$. This result eliminates the possible tension emerging when comparing analytic continuation with earlier results obtained via Taylor expansion.

    ↳ hep-lathep-phhep-thPRD(2018)·156 citations
23. 23*

    A plausible solution to the problem of initial conditions for inflation

    Suratna Das🇮🇳 · Raghavan Rangarajan🇮🇳

    We propose yet another solution to the initial condition problem of inflation associated with homogeneity beyond the horizon at the onset of inflation, in cases where inflation is preceded by a radiation era. One may argue that causality will allow for smoothness over the causal horizon scale $H^{-1}$, but for thermal inflationary scenarios, the background inflaton field will only be correlated over the thermal correlation length $\zeta \sim T^{-1}$ which is much smaller than $H^{-1}$. We argue, with examples, that if the number of relativistic degrees of freedom in the pre-inflationary era is very large $(>10^4)$ then the thermal correlation length can be of the order of the causal horizon size alleviating the initial conditions problem of inflation.

    ↳ astro-ph.COgr-qchep-phInt.J.Mod.Phys.D(2019)·2 citations
24. 24*

    Evaporating the Milky Way halo and its satellites with inelastic self-interacting dark matter

    Mark Vogelsberger (MIT)🇺🇸 · Jesús Zavala (University of Iceland)🇮🇸 · Katelin Schutz (Berkeley)🇺🇸 · Tracy R. Slatyer (MIT)🇺🇸

    Self-interacting dark matter provides a promising alternative for the cold dark matter paradigm to solve potential small-scale galaxy formation problems. Nearly all self-interacting dark matter simulations so far have considered only elastic collisions. Here we present simulations of a galactic halo within a generic inelastic model using a novel numerical implementation in the Arepo code to study arbitrary multi-state inelastic dark matter scenarios. For this model we find that inelastic self-interactions can: (i) create larger subhalo density cores compared to elastic models for the same cross section normalisation; (ii) lower the abundance of satellites without the need for a power spectrum cutoff; (iii) reduce the total halo mass by about 10%; (iv) inject the energy equivalent of O(100) million Type II supernovae in galactic haloes through level de-excitation; (v) avoid the gravothermal catastrophe due to removal of particles from halo centers. We conclude that a ~5 times larger elastic cross section is required to achieve the same central density reduction as the inelastic model. This implies that well-established constraints on self-interacting cross sections have to be revised if inelastic collisions are the dominant mode. In this case significantly smaller cross sections can achieve the same core density reduction thereby increasing the parameter space of allowed models considerably.

    ↳ astro-ph.GAhep-phMNRAS(2019)·106 citations
25. 25*

    Investigating the high-frequency spectral features of SNRs Tycho, W44 and IC443 with the Sardinia Radio Telescope

    S. Loru🇮🇹 · A. Pellizzoni🇮🇹 · E. Egron🇮🇹 · S. Righini🇮🇹 · M. N. Iacolina🇮🇹 · S. Mulas🇮🇹 · M. Cardillo🇮🇹 · M. Marongiu🇮🇹 · R. Ricci🇮🇹 · M. Bachetti🇮🇹 · M. Pilia🇮🇹 · A. Trois🇮🇹 and 11 other authors

    The main characteristics in the radio continuum spectra of Supernova Remnants (SNRs) result from simple synchrotron emission. In addition, electron acceleration mechanisms can shape the spectra in specific ways, especially at high radio frequencies. These features are connected to the age and the peculiar conditions of the local interstellar medium interacting with the SNR. Whereas the bulk radio emission is expected at up to $20-50$ GHz, sensitive high-resolution images of SNRs above 10 GHz are lacking and are not easily achievable, especially in the confused regions of the Galactic Plane. In the framework of the early science observations with the Sardinia Radio Telescope in February-March 2016, we obtained high-resolution images of SNRs Tycho, W44 and IC443 that provided accurate integrated flux density measurements at 21.4 GHz: 8.8 $\pm$ 0.9 Jy for Tycho, 25 $\pm$ 3 Jy for W44 and 66 $\pm$ 7 Jy for IC443. We coupled the SRT measurements with radio data available in the literature in order to characterise the integrated and spatially-resolved spectra of these SNRs, and to find significant frequency- and region-dependent spectral slope variations. For the first time, we provide direct evidence of a spectral break in the radio spectral energy distribution of W44 at an exponential cutoff frequency of 15 $\pm$ 2 GHz. This result constrains the maximum energy of the accelerated electrons in the range $6-13$ GeV, in agreement with predictions indirectly derived from AGILE and \textit{Fermi}-LAT gamma-ray observations. With regard to IC443, our results confirm the noticeable presence of a bump in the integrated spectrum around $20-70$ GHz that could result from a spinning dust emission mechanism.

    ↳ astro-ph.HEastro-ph.GAhep-phMNRAS(2019)·16 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.