Wed·May 30, 2018Wednesday·May 30, 2018

1. 01*

   Common Origin of Dirac Neutrino Mass and Freeze-in Massive Particle Dark Matter

   Debasish Borah🇮🇳 · Biswajit Karmakar🇮🇳 · Dibyendu Nanda🇮🇳

   Motivated by the fact that the origin of tiny Dirac neutrino masses via the standard model Higgs field and non-thermal dark matter populating the Universe via freeze-in mechanism require tiny dimensionless couplings of similar order of magnitudes $(\sim 10^{-12})$, we propose a framework that can dynamically generate such couplings in a unified manner. Adopting a flavour symmetric approach based on $A_4$ group, we construct a model where Dirac neutrino coupling to the standard model Higgs and dark matter coupling to its mother particle occur at dimension six level involving the same flavon fields, thereby generating the effective Yukawa coupling of same order of magnitudes. The mother particle for dark matter, a complex scalar singlet, gets thermally produced in the early Universe through Higgs portal couplings followed by its thermal freeze-out and then decay into the dark matter candidates giving rise to the freeze-in dark matter scenario. Some parts of the Higgs portal couplings of the mother particle can also be excluded by collider constraints on invisible decay rate of the standard model like Higgs boson. We show that the correct neutrino oscillation data can be successfully produced in the model which predicts normal hierarchical neutrino mass. The model also predicts the atmospheric angle to be in the lower octant if the Dirac CP phase lies close to the presently preferred maximal value.

   hep-phJCAP(2018)·49 citations
2. 02*

   Universal Extra Dimension models with gravity mediated decays after LHC Run II data

   Kirtiman Ghosh🇮🇳 · Durmus Karabacak🇹🇷 · S. Nandi🇺🇸

   In the 'fat-brane' realization of Universal Extra Dimension (UED) models, the gravity mediated decays of Kaluza-Klein (KK) excitations of the Standard Model (SM) particles offer interesting collider signals. Colored level-1 KK-particles (quarks $q^1$ and/or gluons $g^1$) are pair-produced at the colliders due to conserved KK-parity. These particles, then, cascade decay into lighter level-1 KK-particle in association with one or more SM particles until producing lightest KK particle (LKP). The gravity mediation allows LKP to decay into photon or $Z$-boson plus gravity excitation, hence resulting in di-photon/$ZZ$/$Z\gamma$ plus missing transverse energy signatures at collider experiments. Alternatively, pair-produced level-1 KK quarks/gluons may directly decay into the corresponding SM quark/gluon and a gravity excitation resulting in di-jet plus missing transverse energy signal. The ATLAS Collaboration has recently communicated the results for di-photon and multi-jet plus missing transverse energy searches with $36.1$ inverse-femtobarn of integrated luminosity at $13$ TeV center-of-mass energy. No significant excess of events above the SM expectation was observed in both searches. We constrain the 'fat-brane' UED model parameters, namely the fundamental Planck mass $M_D$ and the size of small extra dimensions $R$, in the light of above-mentioned ATLAS searches.

   hep-phhep-thPLB(2019)·8 citations
3. 03*

   Dipolar dark matter and CMB B-mode polarization

   S. Mahmoudi🇮🇷 · M. Haghighat🇮🇷 · S. Modares Vamegh🇮🇷 · R. Mohammadi🇮🇷

   We consider dark matter as singlet fermionic particles which carrying magnetic dipole moment to explore its contribution on the polarization of cosmic microwave background (CMB) photons. We show that Dirac fermionic dark matter has no contribution on the CMB polarization. However, in the case of Majorana dark matter this type of interaction leads to the B-mode polarization in presence of primordial scalar perturbations which is in contrast with standard scenario for the CMB polarization. We numerically calculate the B-mode power spectra and plot $C_l^{BB}$ for different dark matter masses and the $r$-parameter. We show that the dark matter with masses less than 100MeV have valuable contribution on $C_l^{BB}$. Meanwhile, the dark matters with mass $m_d\le 50MeV$ for $r=0.07$ ( $m_d\le 80MeV$ for $r=0.09$) can be excluded experimentally. Furthermore, our results put a bound on the magnetic dipole moment about $M\le 10^{-16}ecm$ in agreement with the other reported constraints.

   hep-phastro-ph.COastro-ph.HEEPJC(2020)·7 citations
4. 04*

   Study of $B\to \pi \ell {\nu }_{\ell }$ and $B^{+}\to {\eta }^{(\prime )}{\ell }^{+}{\nu }_{\ell }$ decays and determination of $|V_{ub}|$

   Sergi Gonzàlez-Solís🇨🇳 · Pere Masjuan🇪🇸

   We reassess the $B\to \pi \ell {\nu }_{\ell }$ differential branching ratio distribution experimental data released by the BaBar and Belle Collaborations supplemented with all lattice calculations of the $B\to \pi$ form factor shape available up to date obtained by the HPQCD, FNAL/MILC and RBC/UKQCD Collaborations. Our study is based on the method of Padé approximants, and includes a detailed scrutiny of each individual data set that allow us to obtain $|V_{ub}|=3.53(8{)}_{\mathrm{stat}}(6{)}_{\mathrm{syst}}\times 10^{-3}$. The semileptonic $B^{+}\to {\eta }^{(\prime )}{\ell }^{+}{\nu }_{\ell }$ decays are also addressed and the $\eta$-${\eta }^{\prime }$ mixing discussed.

   hep-phhep-exhep-latPRD(2018)·14 citations
5. 05*

   A possible interpretation of the newly observed $\Omega (2012)$ state

   Li-Ye Xiao🇨🇳 · Xian-Hui Zhong🇨🇳

   Inspired by the newly observed $\Omega (2012)$ state at Belle II, we investigate the two-body strong decays of $\Omega$ baryons up to $N=2$ shell within the chiral quark model. Our results indicate that: (i) the newly observed $\Omega (2012)$ state could be assigned to the spin-parity $J^P=3/2^{-}$ state $|70{,}^{2}10,1,1,{\frac{3}{2}}^{-}⟩$ and the experimental data can be reasonably described. However, the spin-parity $J^P=1/2^{-}$ state $|70{,}^{2}10,1,1,{\frac{1}{2}}^{-}⟩$ and spin-parity $J^P=3/2^{+}$ state $|56{,}^{4}10,2,0,{\frac{3}{2}}^{+}⟩$ can't be completely excluded. (ii) The $D$-wave states in the $N=2$ shell are most likely to be narrow states with a width of dozens of MeV and have a good potential to be observed in the $\Xi K$ and/or $\Xi (1530)K$ channels in future experiments. The $\Omega (2250)$ resonance listed in PDG may be a good candidate of the $J^P=5/2^{+}$ $1D$ wave state $|56{,}^{4}10,2,2,5/2^{+}⟩$.

   hep-phPRD(2018)·50 citations
6. 06*

   Central and peripheral hadron-nucleus collisions in the Additive Quark Model

   G.H. Arakelyan🇦🇲 · Yu.M. Shabelski🇷🇺 · A.G. Shuvaev🇷🇺

   Peripheral nucleon-nucleus collisions occur at the high energies mainly through the interaction with one constituent quark from the incident nucleon. The central collisions should involve all three constituent quarks and each of them can interact several times. We calculate the average number of quark-nucleus interactions for both the cases in good agreement with the experimental data on $\varphi$-meson, $K^{\ast 0}$ and all charged secondaries productions in $p+Pb$ collisions at LHC energy $\sqrt{s}=5$ TeV.

   hep-phMod.Phys.Lett.A(2019)·1 citation
7. 07*

   Neutralino/chargino pair production at NLO+NLL with resummation-improved PDFs for LHC Run II

   J. Fiaschi🇩🇪 · M. Klasen🇩🇪

   We make use of recently released parton density functions (PDFs) with threshold-resummation improvement to consistently calculate theoretical predictions for neutralino and chargino pair production at next-to-leading order and next-to-leading logarithmic accuracy. The updated cross sections have been computed for experimentally relevant higgsino and gaugino search channels at the ongoing Run II of the LHC. A factorisation method is applied to exploit the smaller PDF uncertainty of the global PDF sets and to avoid complications arising in the refitting of threshold-resummation improved PDF replicas in Mellin space. The reduction of the scale uncertainty due to the resummation is, however, explicitly taken into account. As expected, the resummation contributions in the PDF fits partially compensate the cross section enhancements induced by those in the partonic matrix elements.

   hep-phhep-exPRD(2018)·102 citations
8. 08*

   Lepton Flavor Violating Dilepton Dijet Signatures from Sterile Neutrinos at Proton Colliders

   Stefan Antusch🇨🇭 · Eros Cazzato🇨🇭 · Oliver Fischer🇩🇪 · A. Hammad🇨🇭 · Kechen Wang🇨🇳

   In this article we investigate the prospects of searching for sterile neutrinos in lowscale seesaw scenarios via the lepton flavour violating (but lepton number conserving) dilepton dijet signature. In our study, we focus on the final state $e^{\pm }{\mu }^{\mp }jj$ at the HL-LHC and the FCC-hh (or the SppC). We perform a multivariate analysis at the detector level including the dominant SM backgrounds from di-top, di-boson, and tri-boson. Under the assumption of the active-sterile neutrino mixings $|V_{lN}{|}^2=|{\theta }_e{|}^2=|{\theta }_{\mu }{|}^2$ and $|V_{\tau N}{|}^2=|{\theta }_{\tau }{|}^2=0$, the sensitivities on the signal production cross section times branching ratio $\sigma (pp\to l^{\pm }N)\times \mathrm{BR}(N\to l^{\mp }jj)$ and on $|V_{lN}{|}^2$ for sterile neutrino mass $M_N$ between 200 and 1000 GeV are derived. For the benchmark $M_N=500$ GeV, when ignoring systematic uncertainties at the HL-LHC (FCC-hh/SppC) with 3 (20) ${\mathrm{ab}}^{-1}$ luminosity, the resulting 2-$\sigma$ limits on $|V_{lN}{|}^2$ are $4.9\times 10^{-3}$ ($7.0\times 10^{-5}$), while the 2 -$\sigma$ limit on $\sigma \times \mathrm{BR}$ are $4.4\times 10^{-2}$ ($1.6\times 10^{-2}$) fb, respectively. The effect of the systematic uncertainty is also studied and found to be important for sterile neutrinos with smaller masses. We also comment on searches with ${\tau }^{\pm }{\mu }^{\mp }jj$ and ${\tau }^{\pm }{e}^{\mp }jj$ final states.

   hep-phhep-exJHEP(2018)·46 citations
9. 09*

   Establishing a Search for $b\to s{\ell }^{+}{\ell }^{-}$ Anomalies at the LHC

   Yoav Afik🇮🇱 · Jonathan Cohen🇮🇱 · Eitan Gozani🇮🇱 · Enrique Kajomovitz🇮🇱 · Yoram Rozen🇮🇱

   One of the fundamental predictions of the Standard Model is Lepton Flavour Universality. Any deviation from this prediction would indicate the existence of physics beyond the Standard Model. Recent LHCb measurements present a pattern of deviations from this prediction in rare B-meson decays. While not yet statistically significant (currently $2.2-2.6\sigma$), these measurements show an imbalance in the ratio of B-meson decays to a pair of muons in association with a Kaon and decays to a pair of electrons in association with a Kaon. If the measured deviations are indeed present in nature, new physics may mediate interactions involving a pair of same flavour leptons, a $b$- and an $s$-quark. We present the prospect for a search of new physics in this type of interactions at the LHC, in a process that involves an $s$-quark, and a final state with two leptons and a $b$-jet. The proposed search can improve the sensitivity to new physics in these processes by a factor of four compared to current searches with in the total dataset expected at the LHC.

   hep-phhep-exJHEP(2018)·39 citations
10. 10*

    Supersymmetry in the Double-Heavy Hadronic Spectrum

    Marina Nielsen🇧🇷 · Stanley J. Brodsky🇺🇸 · Guy F. de Téramond🇨🇷 · Hans Günter Dosch🇩🇪 · Fernando S. Navarra🇧🇷 · Liping Zou🇨🇳

    Relativistic light-front bound-state equations for double-heavy mesons, baryons and tetraquarks are constructed in the framework of supersymmetric light front holographic QCD. Although heavy quark masses strongly break conformal symmetry, supersymmetry and the holographic embedding of semiclassical light-front dynamics still holds. The theory, derived from five-dimensional anti-de Sitter space, predicts that the form of the confining potential in the light-front Hamiltonian is harmonic even for heavy quarks. Therefore, the basic underlying supersymmetric mechanism, which transforms meson-baryon and baryon-tetraquark wave functions into each other, can also be applied to the double-heavy sector; one can then successfully relate the masses of the double-heavy mesons to double-heavy baryons and tetraquarks. The dependence of the confining potential on the hadron mass scale agrees completely with the one derived in heavy light systems from heavy quark symmetry. We also make predictions for higher excitations of the charmonium and bottomonium states. In particular, the remarkable equality of the Regge slopes in the orbital angular momentum, $L$, and the principal quantum number, $n$, is predicted to remain valid.

    hep-phPRD(2018)·42 citations
11. 11*

    Consistency test of the AMS-02 antiproton excess with direct detection data based on the effective field theory approach

    Ming-Yang Cui🇨🇳 · Wei-Chih Huang🇩🇰 · Yue-Lin Sming Tsai🇹🇼 · Qiang Yuan🇨🇳

    The potential antiproton excess in the AMS-02 data is of much interest and can probably come from dark matter annihilations. Based on the effective field theory approach, in this work we investigate the compatibility of the DM interpretation of the AMS-02 antiproton excess and the null results from direct detection experiments, LUX, PandaX-II, and XENON1T. We focus on dimension-five and -six operators with fermion DM. Only one of dimension-five and one of dimension-six operators can successfully account for the antiproton excess, while the rest either are excluded by direct detection or require very small cut-off scales which invalidate the effective field theory approach.

    hep-phastro-ph.HEJCAP(2018)·8 citations
12. 12*

    Photon isolation and jet substructure

    Eleanor Hall🇺🇸 · Jesse Thaler🇺🇸

    We introduce soft drop isolation, a new photon isolation criterion inspired by jet substructure techniques. Soft drop isolation is collinear safe and is equivalent to Frixione isolation at leading non-trivial order in the small R limit. However, soft drop isolation has the interesting feature of being democratic, meaning that photons can be treated equivalently to hadrons for initial jet clustering. Taking advantage of this democratic property, we define an isolated photon subjet: a photon that is not isolated from its parent jet but is isolated within its parent subjet after soft drop declustering. The kinematics of this isolated photon subjet can be used to expose the QED splitting function, in which a quark radiates a photon, and we verify this behavior using both a parton shower generator and a perturbative calculation in the collinear limit.

    hep-phhep-exJHEP(2018)·22 citations
13. 13*

    Strange form factors of nucleon with nonlocal chiral effective Lagrangian

    Fangcheng He🇨🇳 · P. Wang🇨🇳

    The strange form factors of nucleon are studied with the nonlocal chiral effective Lagrangian. One loop contributions from both octet and decuplet intermediate states are included. The relativistic regulator is obtained by the nonlocal Lagrangian where the gauge link is introduced to guarantee the local gauge symmetry. With the kaon loop, the calculated charge form factor is positive, while the magnetic form factor is negative. The strange magnetic moment is $-0.041_{-0.014}^{+0.012}$ with $\Lambda =0.9\pm 0.1$ determined from the nucleon electromagnetic form factors. Our results are comparable with the recent lattice simulation.

    hep-phPRD(2018)·19 citations
14. 14*

    Opening a New Window onto the Universe with IceCube

    Markus Ahlers🇩🇰 · Francis Halzen🇺🇸

    Weakly interacting neutrinos are ideal astronomical messengers because they travel through space without deflection by magnetic fields and, essentially, without absorption. Their weak interaction also makes them notoriously difficult to detect, with observation of high-energy neutrinos from distant sources requiring kilometer-scale detectors. The IceCube project transformed a cubic kilometer of natural Antarctic ice at the geographic South Pole into a Cherenkov detector. It discovered a flux of cosmic neutrinos in the energy range from 10 TeV to 10 PeV, predominantly extragalactic in origin. Their corresponding energy density is close to that of high-energy photons detected by gamma-ray satellites and ultra-high-energy cosmic rays observed with large surface detectors. Neutrinos are therefore ubiquitous in the nonthermal universe, suggesting a more significant role of protons (nuclei) relative to electrons than previously anticipated. Thus, anticipating an essential role for multimessenger astronomy, IceCube is planning significant upgrades of the present instrument as well as a next-generation detector. Similar detectors are under construction in the Mediterranean Sea and Lake Baikal.

    ↳ astro-ph.HEhep-phPPNP(2018)·165 citations
15. 15*

    Bulk viscosity coefficient of hadronic matter

    Sabyasachi Ghosh🇮🇳 · Sandeep Chatterjee🇮🇳 · Bedangadas Mohanty🇮🇳

    The bulk viscosity coefficient of hadronic matter has been estimated in this present work, where the thermodynamical equilibrium quantity like speed of sound in the medium has been obtained by using standard hadron resonance gas model. Whereas, the non-equilibrium quantity like thermal widths of medium constituents have been calculated in the framework field theory at finite temperature. Our values of bulk viscosity coefficient are in agreement with some earlier estimations.

    ↳ nucl-thhep-phnucl-exSpringer Proc.Phys.(2018)·0 citations
16. 16*

    From homogeneous matter to finite nuclei: Role of the effective mass

    Hana Gil🇰🇷 · Panagiota Papakonstantinou🇰🇷 · Chang Ho Hyun🇰🇷 · Yongseok Oh🇰🇷

    Recent astronomical observations, nuclear-reaction experiments, and microscopic calculations have placed new constraints on the nuclear equation of state (EoS) and revealed that most nuclear structure models fail to satisfy those constraints upon extrapolation to infinite matter. A reverse procedure for imposing EoS constraints on nuclear structure has been elusive. Here we present for the first time a method to generate a microscopic energy density functional (EDF) for nuclei from a given immutable EoS. The method takes advantage of a natural Ansatz for homogeneous nuclear matter, the Kohn-Sham framework, and the Skyrme formalism. We apply it to the realistic nuclear EoS of Akmal-Pandharipande-Ravenhall and describe successfully closed-(sub)shell nuclei. In the process, we provide predictions for the neutron skin thickness of nuclei based directly on the given EoS. Crucially, bulk and static nuclear properties are found practically independent of the assumed effective mass value - a unique result in bridging EDF of finite and homogeneous systems in general.

    ↳ nucl-thhep-phPRC(2019)·46 citations
17. 17*

    ${\Lambda }^{\ast }(1405)$-matter: stable or unstable?

    Jaroslava Hrtánková🇨🇿 · Nir Barnea🇮🇱 · Eliahu Friedman🇮🇱 · Avraham Gal🇮🇱 · Jiří Mareš🇨🇿 · Martin Schäfer🇨🇿

    A recent suggestion [PLB 774 (2017) 522] that purely-${\Lambda }^{\ast }(1405)$ nuclei provide the absolute minimum energy in charge-neutral baryon matter for baryon-number $A\gtrsim 8$, is tested within RMF calculations. A broad range of ${\Lambda }^{\ast }$ interaction strengths, commensurate with $(\bar{K}\bar{K}NN{)}_{I=0}$ binding energy assumed to be of order 100 MeV, is scanned. It is found that the binding energy per ${\Lambda }^{\ast }$, $B/A$, saturates for $A\gtrsim 120$ with values of $B/A$ considerably below 100 MeV, implying that ${\Lambda }^{\ast }(1405)$ matter is highly unstable against strong decay to $\Lambda$ and $\Sigma$ hyperon aggregates. The central density of ${\Lambda }^{\ast }$ matter is found to saturate as well, at roughly twice nuclear matter density. Moreover, it is shown that the underlying very strong $\bar{K}N$ potentials, fitted for isospin $I=0$ to the mass and width values of ${\Lambda }^{\ast }(1405)$, fail to reproduce values of single-nucleon absorption fractions deduced across the periodic table from $K^{-}$ capture-at-rest bubble chamber experiments.

    ↳ nucl-thhep-phnucl-exPLB(2018)·15 citations
18. 18*

    Deuteron production from phase-space coalescence in the UrQMD approach

    Sukanya Sombun🇹🇭 · Kristiya Tomuang🇹🇭 · Ayut Limphirat🇹🇭 · Paula Hillmann🇩🇪 · Christoph Herold🇹🇭 · Jan Steinheimer🇩🇪 · Yupeng Yan🇹🇭 · Marcus Bleicher🇩🇪

    UrQMD phase-space coalescence calculations for the production of deuterons are compared with available data for various reactions from the GSI/FAIR energy regime up to LHC. It is found that the production process of deuterons, as reflected in their rapidity and transverse momentum distributions in p+p, p+A and A+A collisions at a beam energies starting from the GSI energy regime around 1 AGeV and up to the LHC, are in good agreement with experimental data. We further explore the energy and centrality dependence of the d/p ratios. Finally, we discuss anti-deuteron production for selected systems. Overall, a good description of the experimental data is observed. The results are also compatible with thermal model estimates. Most importantly this good description is based only on a single set of coalescence parameters that is independent of energy system size and can also be applied for anti-deuterons.

    ↳ nucl-thhep-phnucl-exPRC(2019)·120 citations
19. 19*

    Resonant feedback for axion and hidden sector dark matter searches

    Edward J. Daw🇬🇧

    Resonant feedback circuits are proposed as an alternative to normal modes of conducting wall cavities or lumped circuits in searches for hidden sector particles. The proposed method offers several potential advantages over the most sensitive axion searches to date, that employ cavity resonators, including coverage of a wider range of axion masses, the ability to probe many axion masses simultaneously, and the elimination of experimentally troublesome mechanical tuning rod mechanisms. After an outline of the proposed method, we present a noise budget for a straw-man experiment configuration. We show that the proposed experiment has the potential to probe the axion mass range 2-40 micro-eV with 38 days of integration time. Other existing and proposed resonant searches for hidden sector particles may also benefit from this approach to detection.

    ↳ physics.ins-dethep-exhep-phNucl.Instrum.Meth.A(2019)·8 citations
20. 20*

    The `unitarity problem' of Higgs inflation in the light of collapse dynamics

    Suratna Das🇮🇳

    Higgs inflation scenario is one of the most compelling models of inflation at present time. It not only explains the observed data well, but also provides means to include the inflaton field within the well understood Standard Model of particle physics, without invoking any need for its extension. Despite this, due to the requirement of large non-minimal coupling to the curvature scalar of the inflaton field, or in this case the Higgs field, this model suffers from a problem often called as the `unitarity' or the `naturalness' problem. On the other hand, to address the longstanding `interpretational issue' of quantum to classical transition of the primordial modes, the collapse dynamics of quantum mechanics has recently been included into the inflationary mechanism. We show that inclusion of such collapse mechanism in Higgs inflation helps alleviate the `unitarity problem' to a great deal.

    ↳ astro-ph.COgr-qchep-phquant-phJCAP(2018)·3 citations
21. 21*

    Trans-Ejecta High-Energy Neutrino Emission from Binary Neutron Star Mergers

    Shigeo S. Kimura🇺🇸 · Kohta Murase🇺🇸 · Imre Bartos🇺🇸 · Kunihito Ioka🇯🇵 · Ik Siong Heng🇬🇧 · Peter Mészáros🇺🇸

    The observations of a macronova/kilonova accompanied by gravitational waves from a binary neutron star merger (GW170817) confirmed that neutron star coalescences produce copious ejecta. The coincident gamma-ray detection implies the existence of a relativistic jet in this system. During the jet's propagation within the ejecta, high-energy photons and neutrinos can be produced. The photons are absorbed by the ejecta, while the neutrinos escape and can be detected. Here, we estimate such trans-ejecta neutrino emission, and discuss how neutrino observations could be used to differentiate between gamma-ray burst emission scenarios. We find that neutrinos from the internal shocks inside the ejecta may be detectable by IceCube within a few years of operation, and will likely be detected with IceCube-Gen2. The neutrino signals coincident with gravitational waves would enable us to reveal the physical quantities of the choked jets even without electromagnetic signals.

    ↳ astro-ph.HEgr-qchep-phPRD(2018)·92 citations
22. 22*

    Dark Matter Interactions, Helium, and the CMB

    Roland de Putter🇺🇸 · Olivier Doré🇺🇸 · Jérôme Gleyzes🇺🇸 · Daniel Green🇺🇸 · Joel Meyers🇨🇦

    The cosmic microwave background (CMB) places a variety of model-independent constraints on the strength interactions of the dominant component of dark matter with the Standard Model. Percent-level subcomponents of the dark matter can evade the most stringent CMB bounds by mimicking the behavior of baryons, allowing for larger couplings and novel experimental signatures. However, in this note, we will show that such tightly coupled subcomponents leave a measurable imprint on the CMB that is well approximated by a change to the helium fraction, $Y_{\mathrm{He}}$. Using the existing constraint on $Y_{\mathrm{He}}$, we derive a new upper limit on the fraction of tightly coupled dark matter, $f_{\mathrm{TCDM}}$, of $f_{\mathrm{TCDM}}<0.006$ (95\% C.I.). We show that future CMB experiments can reach $f_{\mathrm{TCDM}}<0.001$ (95\% C.I.) and confirm that the bounds derived in this way agree with the results of a complete analysis. We briefly comment on the implications for model building, including milli-charged dark matter.

    ↳ astro-ph.COhep-phPRL(2019)·43 citations
23. 23*

    Efficient Computation of Galaxy Bias with Neutrinos and Other Relics

    Julian B. Muñoz🇺🇸 · Cora Dvorkin🇺🇸

    Cosmological data can be used to search for---and characterize---light particles in the standard model, if these populate our Universe. In addition to the well-known effect of these light relics in the background cosmology, usually parametrized through a change in the effective number $N_{\mathrm{eff}}$ of neutrino species, these particles can become nonrelativistic at later times, affecting the growth of matter fluctuations due to their thermal velocities. An extensively studied example is that of massive neutrinos, which are known to produce a suppression in the matter power spectrum due to their free streaming. Galaxies, as biased traces of matter fluctuations, can therefore provide us with a wealth of information about both known and unknown degrees of freedom in the standard model. To harness this information, however, the galaxy bias has to be determined in the presence of massive relics, which is expected to vary with scale. Here we present the code RelicFast, which efficiently computes the scale-dependent bias induced by relics of different masses, spins, and temperatures, through spherical collapse and the peak-background split. Using this code, we find that, in general, the bias induced by light relics partially compensates the suppression of power, and should be accounted for in any search for relics with galaxy data. In particular, for the case of neutrinos, we find that both the normal and inverted hierarchies present a percent-level step in the Lagrangian bias, with a size scaling linearly with the neutrino-mass sum, in agreement with recent simulations. RelicFast can compute halo bias in under a second, allowing for this effect to be properly included for different cosmologies, and light relics, at little computational cost.

    ↳ astro-ph.COhep-phPRD(2018)·59 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.