HEP Phenomenology·hep-ph

Mon·Jul 17, 2017Monday·July 17, 2017

25 papers—19 primary·6 cross-listed·reconstructed*

01*
High-energy resummation in semi-hard processes at the LHC
Francesco Giovanni Celiberto🇮🇹
Semi-hard processes in the large COM energy limit offer us an exclusive chance to test the dynamics behind strong interactions in kinematical sectors so far unexplored. In the Regge limit, fixed-order calculations in pQCD based on collinear factorisation miss the effect of large energy logs, which are so large to compensate the small QCD coupling $α_{s}$ and must therefore be accounted for to all perturbative orders.. The BFKL approach represents the most powerful tool to resum to all orders these large logs both in the LLA and in the NLA. The inclusive hadroproduction of forward jets with high transverse momenta separated by a large rapidity interval at the LHC (Mueller--Navelet jets) has been one of the most studied reactions so far. Interesting observables associated to this process are the azimuthal correlations, showing a very good agreement with experimental data at the LHC. However, new BFKL-sensitive observables should be considered in the context of the LHC physics program. With the aim the to further and deeply probe the dynamics of QCD in the Regge limit, we give phenomenological predictions for four distinct semi-hard process. On one hand, we continue the analysis of reactions with two objects identified in the final state $(i)$ by addressing open problems in the Mueller--Navelet sector and $(ii)$ by studying the inclusive dihadron production in the full NLA BKFL accuracy. On the other hand, we show how inclusive multi-jet production processes allow us to define new, generalised and suitable BFKL observables, where transverse momenta and rapidities of the tagged jets, well separated in rapidity from each other, appear in new combinations. We give the first predictions for the inclusive three-jet production, encoding the effects of higher-order BFKL corrections. Then, making use of the same formalism, we present the first complete BFKL analysis for the four-jet production.
hep-phhep-th55 citations
02*
Indication for Double Parton Scatterings in W + Prompt J/Psi Production at the LHC
Jean-Philippe Lansberg🇫🇷 · Hua-Sheng Shao🇫🇷 · Nodoka Yamanaka🇫🇷
We re-analyse the associated production of a prompt J/psi and a W boson in pp collisions at the LHC following the results of the ATLAS Collaboration. We perform the first study of the Single-Parton-Scattering (SPS) contributions at the Next-to-Leading Order (NLO) in alpha_s in the Colour-Evaporation Model (CEM), an approach based on the quark-hadron-duality. Our study provides clear indications for Double-Parton-Scattering (DPS) contributions, in particular at low transverse momenta, since our SPS CEM evaluation, which can be viewed as a conservative upper limit of the SPS yields, falls short compared to the ATLAS experimental data by 3.1 standard deviations. We also determine a finite allowed region for sigma_eff, inversely proportional to the size of the DPS yields, corresponding to the otherwise opposed hypotheses, namely our NLO CEM evaluation and the LO direct Colour-Singlet (CS) Model contribution. In both cases, the resulting DPS yields are significantly larger than that initially assumed by ATLAS based on jet-related analyses but is consistent with their observed raw-yield azimuthal distribution and with their prompt J/psi+J/psi and Z + prompt J/psi data.
hep-phhep-exPLB(2018)·49 citations
03*
The quark propagator in the complex domain: A status report
Andreas Windisch🇺🇸
In these proceedings I review the status of an ongoing project that aims at solving the quark propagator Dyson-Schwinger equation in the complex domain. The novel aspect of the approach is that the non-analyticities arising throughout the iteration of the equation are to be taken into account in an appropriate way through dynamic contour deformation. Because of the complexity of the approach, these studies are undertaken in a heavily truncated scenario that serves as a toy model for the development of the numerical techniques that are required to treat the system in a mathematically sound way.
hep-phnucl-thActa Phys.Polon.Supp.(2017)·0 citations
04*
Spin 1 low lying meson spectra and the subtle link to the spin 0 mesons
Jorge Morais🇵🇹 · Brigitte Hiller🇵🇹 · Alexander A. Osipov🇷🇺
An NJL-type three-flavor quark model with a complete set of explicit chiral symmetry breaking terms is extended to include vector and axial vector effective interaction terms. The bosonized Lagrangian is written up to quadratic order in the bosonic fields and the role of the new interactions is analysed in detail. The model's parameters are fitted to yield reasonable values to the four low-lying spin 0 and spin 1 meson nonets' masses.
hep-phActa Phys.Polon.Supp.(2017)·0 citations
05*
A supersymmetric electroweak scale seesaw model
Jung Chang🇰🇷 · Kingman Cheung🇹🇼 · Hiroyuki Ishida🇹🇼 · Chih-Ting Lu🇹🇼 · Martin Spinrath🇹🇼 · Yue-Lin Sming Tsai🇹🇼
In this paper we propose a novel supersymmetric inverse seesaw model which has only one additional $Z_{6}$ symmetry. The field content is minimal to get a viable neutrino spectrum at tree-level. Interestingly, the inverse seesaw scale in our model is related to the scale of electroweak symmetry breaking. Due to that origin we are less biased about hierarchies and discuss three different types of the inverse seesaw mechanism with different phenomenologies. We can successfully reproduce neutrino masses and mixing and our model is consistent with current bounds on neutrinoless double beta decay, non-unitarity of the PMNS matrix and charged lepton flavor violation.
hep-phJHEP(2017)·14 citations
06*
Correlation functions of net-proton multiplicity distributions in Au + Au collisions at energies available at the BNL Relativistic Heavy Ion Collider from a multiphase transport model
Yufu Lin🇨🇳 · Lizhu Chen🇨🇳 · Zhiming Li🇨🇳
Fluctuations of conserved quantities are believed to be sensitive observables to probe the signature of the QCD phase transition and critical point. It was argued recently that measuring the genuine correlation functions (CFs) could provide cleaner information on possible nontrivial dynamics in heavy-ion collisions.With the AMPT (a multiphase transport) model, the centrality and energy dependence of various orders of CFs of net protons in Au + Au collisions at $s_{NN}$ =7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV are investigated. The model results show that the number of antiprotons is important and should be taken into account in the calculation of CFs at high energy and/or in peripheral collisions. It is also found that the contribution of antiprotons is more important for higher order correlations than for lower ones. The CFs of antiprotons and mixed correlations play roles comparable to those of protons at high energies. Finally, we make comparisons between the model calculation and experimental data measured in the STAR experiment at the BNL Relativistic Heavy Ion Collider.
hep-phhep-exnucl-exPRC(2017)·10 citations
07*
Impact of generalized Yukawa interactions on the lower Higgs mass bound
Holger Gies🇩🇪 · René Sondenheimer🇩🇪 · Matthias Warschinke🇩🇪
We investigate the impact of operators of higher canonical dimension on the lower Higgs mass consistency bound by means of generalized Higgs-Yukawa interactions. Analogously to higher-order operators in the bare Higgs potential in an effective field theory approach, the inclusion of higher-order Yukawa interactions, e.g., $ϕ^{3} ψ ˉ ψ$ , leads to a diminishing of the lower Higgs mass bound and thus to a shift of the scale of new physics towards larger scales by a few orders of magnitude without introducing a metastability in the effective Higgs potential. We observe that similar renormalization group mechanisms near the weak-coupling fixed point are at work in both generalizations of the microscopic action. Thus, a combination of higher-dimensional operators with generalized Higgs as well as Yukawa interactions does not lead to an additive shift of the lower mass bound, but relaxes the consistency bounds found recently only slightly. On the method side, we clarify the convergence properties of different projection and expansion schemes for the Yukawa potential used in the functional renormalization group literature so far.
hep-phhep-thEPJC(2017)·41 citations
08*
Multilepton signals of heavier electroweakinos at the LHC
Manimala Chakraborti🇩🇪 · Amitava Datta🇮🇳 · Nabanita Ganguly🇮🇳 · Sujoy Poddar🇮🇳
As sequel to a recent paper we examine the phenomenology of the full electroweakino sector of the pMSSM without invoking the adhoc but often employed assumption that the heavier ones are decoupled. We identify several generic models which illustrate the importance of the heavier electroweakinos and constrain them with the LHC $3 l$ + $E /_{T}$ data. The constraints are usually stronger than that for decoupled heavier electroweakinos indicating that the LHC data is already sensitive to their presence. We also take into account the constraints from the observed dark matter relic density of the universe and precisely measured anomalous magnetic moment of the muon. Using the allowed parameter space thus obtained, we show that in addition to the conventional $3 l$ + $E /_{T}$ signatures novel multilepton ( $m l$ ) + $E /_{T}$ final states with $m > 3$ , which are not viable in models with lighter electroweakinos only, can be observed before the next long shut down of the LHC.
hep-phJHEP(2017)·13 citations
09*
S-matrix formulation of thermodynamics with N-body scatterings
Pok Man Lo🇵🇱
We apply a phase space expansion scheme to incorporate the N-body scattering processes in the S-matrix formulation of statistical mechanics. A generalized phase shift function suitable for studying the thermal contribution of $N \to N$ processes is motivated and examined in various models. Using the expansion scheme, we revisit how the hadron resonance gas model emerges from the S-matrix framework, and consider an example of structureless scattering in which the phase shift function can be exactly worked out. Finally we analyze the influence of dynamics on the phase shift function in a simple example of 3- and 4-body scattering.
hep-phEPJC(2017)·44 citations
10*
Categorisation and Detection of Dark Matter Candidates from String/M-theory Hidden Sectors
Bobby S. Acharya🇬🇧 · Sebastian A. R. Ellis🇺🇸 · Gordon L. Kane🇺🇸 · Brent D. Nelson🇺🇸 · Malcolm Perry🇬🇧
We study well-motivated dark matter candidates arising from weakly-coupled hidden sectors in compactified string/ $M$ -theory. Imposing generic top-down constraints greatly restricts allowed candidates. By considering the possible mechanisms for achieving the correct dark matter relic density, we compile categories of viable dark matter candidates and annihilation mediators. We consider the case where supersymmetry breaking occurs via moduli stabilisation and is gravitationally mediated to the visible and other hidden sectors, without assuming sequestering of the sector in which supersymmetry is broken. We find that in this case, weakly-coupled hidden sectors only allow for fermionic dark matter. Additionally, most of the mechanisms for obtaining the full relic density only allow for a gauge boson mediator, such as a dark $Z^{'}$ . Given these considerations, we study the potential for discovering or constraining the allowed parameter space given current and future direct detection experiments, and direct production at the LHC. We also present a model of a hidden sector which would contain a satisfactory dark matter candidate.
hep-phhep-thJHEP(2018)·34 citations
11*
LHC Search for Right-handed Neutrinos in $Z^{'}$ Models
Peter Cox🇯🇵 · Chengcheng Han🇯🇵 · Tsutomu T. Yanagida🇯🇵
We consider right-handed neutrino pair production in generic $Z^{'}$ models. We propose a new, model-independent analysis using final states containing a pair of same-sign muons. A key aspect of this analysis is the reconstruction of the RH neutrino mass, which leads to a significantly improved sensitivity. Within the $U (1)_{(B - L)_{3}}$ model, we find that at the HL-LHC it will be possible to probe RH neutrino masses in the range $0.2 ≲ M_{N_{R}} ≲ 1.1$ TeV.
hep-phhep-exJHEP(2018)·37 citations
12*
Analytic approach to pion-kaon scattering and strange resonances
A.Rodas (U. Complutense, Madrid)🇪🇸
We review our analysis of $π K$ scattering using forward dispersion relations. The method yields a set of simple parameterizations that are compatible with forward dispersion relations up to 1.6 GeV while still describing the data. Once the partial waves are obtained, we calculate the poles in the complex plane by means of Padé approximants, thus avoiding a particular model for the pole parameterization. The resonances calculated below 1.8 GeV are the much debated scalar $κ$ -meson, nowadays known as $K_{0}^{*} (800)$ , the scalar $K_{0}^{*} (1430)$ , the $K^{*} (892)$ and $K_{1}^{*} (1410)$ vectors, the spin-two $K_{2}^{*} (1430)$ as well as the spin-three $K_{3}^{*} (1780)$ .
hep-phActa Phys.Polon.Supp.(2017)·0 citations
13*
An i2HDM Strongly Coupled to a non-Abelian Vector Resonance
Felipe Rojas-Abatte🇨🇱 · Maria Luisa Mora🇨🇱 · Jose Urbina🇨🇱 · Alfonso R. Zerwekh🇨🇱
We study the possibility of a Dark Matter candidate having its origin in an extended Higgs sector which, at least partially, is related to a new strongly interacting sector. More concretely, we consider an i2HDM (i.e. a Type-I Two Higgs Doublet Model supplemented with a Z_2 under which the non-standard scalar doublet is odd) based on the gauge group SU(2)_1 x SU(2)_2 x U(1)_Y. We assume that one of the scalar doublets and the standard fermion transform non-trivially under SU(2)_1 while the second doublet transforms under SU(2)_2. Our main hypothesis is that standard sector is weakly coupled while the gauge interactions associated to the second group is characterized by a large coupling constant. We explore the consequences of this construction for the phenomenology of the Dark Matter candidate and we show that the presence of the new vector resonance reduces the relic density saturation region, compared to the usual i2DHM, in the high Dark Matter mass range. In the collider side, we argue that the mono-Z production is the channel which offers the best chances to manifest the presence of the new vector field. We study the departures from the usual i2HDM predictions and show that the discovery of the heavy vector at the LHC is challenging even in the mono- $Z$ channel since the typical cross sections are of the order of 10^{-2} fb.
hep-phhep-exPRD(2017)·7 citations
14*
Flavor-singlet charm pentaquark
Yoya Irie🇯🇵 · Makoto Oka🇯🇵 · Shigehiro Yasui🇯🇵
A new type of charm pentaquark $P_{cs}$ with quark content $c c ˉ u d s$ in light-flavor singlet state is studied in the quark model. This state is analogous to the $P_{c}$ with $c c ˉ uu d$ in light-flavor octet, which was observed in LHC in 2015. Considering various combinations of color, spin and light flavor as internal quantum numbers in $P_{cs}$ , we investigate the mass ordering of the $P_{cs}$ 's by adopting both the one-gluon exchange interaction and the instanton-induced interaction in the quark model. The most stable configuration of $P_{cs}$ is identified to be total spin $1/2$ in which the $c c ˉ$ is combined to be color octet and spin $1$ , while the $u d s$ cluster is in a color octet state. The other color octet configurations, the total spin $1/2$ state with the $c c ˉ$ spin 0 and the state with total spin $3/2$ and $c c ˉ$ spin 1, are found as excited states. We also discuss possible decay modes of these charm pentaquarks.
hep-phPRD(2018)·20 citations
15*
Squark production in R-symmetric SUSY with Dirac gluinos: NLO corrections
Philip Diessner🇩🇪 · Wojciech Kotlarski🇩🇪 · Sebastian Liebschner🇩🇪 · Dominik Stöckinger🇩🇪
R-symmetry leads to a distinct realisation of SUSY with a significantly modified coloured sector featuring a Dirac gluino and a scalar colour octet (sgluon). We present the impact of R-symmetry on squark production at the 13 TeV LHC. We study the total cross sections and their NLO corrections from all strongly interacting states, their dependence on the Dirac gluino mass and sgluon mass as well as their systematics for selected benchmark points. We find that tree-level cross sections in the R-symmetric model are reduced compared to the MSSM but the NLO K-factors are generally larger in the order of ten to twenty per cent. In the course of this work we derive the required DREG $\to$ DRED transition counterterms and necessary on-shell renormalisation constants. The real corrections are treated using FKS subtraction, with results cross checked against an independent calculation employing the two cut phase space slicing method.
hep-phJHEP(2017)·36 citations
16*
Dark matter contribution to $b \to s μ^{+} μ^{-}$ anomaly in local $U (1)_{L_{μ} - L_{τ}}$ model
Seungwon Baek🇰🇷
We propose a local $U (1)_{L_{μ} - L_{τ}}$ model to explain $b \to s μ^{+} μ^{-}$ anomaly observed at the LHCb and Belle experiments. The model also has a natural dark matter candidate $N$ . We introduce $S U (2)_{L}$ -doublet colored scalar $q$ to mediate $b \to s$ transition at one-loop level. The $U (1)_{L_{μ} - L_{τ}}$ gauge symmetry is broken spontaneously by the scalar $S$ . All the new particles are charged under $U (1)_{L_{μ} - L_{τ}}$ . We can obtain $C_{9}^{μ, NP} \sim - 1$ to solve the $b \to s μ^{+} μ^{-}$ anomaly and can explain the correct dark matter relic density of the universe, $Ω_{DM} h^{2} \approx 0.12$ , simultaneously, while evading constraints from electroweak precision tests, neutrino trident experiments and other quark flavor-changing loop processes such as $b \to s γ$ and $B_{s} - B_{s}$ mixing. Our model can be tested by searching for $Z^{'}$ and new colored scalar at the LHC and $B \to K^{*} ν ν$ process at Belle-II.
hep-phPLB(2018)·75 citations
17*
Production of vector resonances at the LHC via WZ-scattering: a unitarized EChL analysis
R. L. Delgado🇪🇸 · A. Dobado🇪🇸 · D. Espriu🇪🇸 · C. Garcia-Garcia🇪🇸 · M.J. Herrero🇪🇸 · X. Marcano🇪🇸 · J.J. Sanz-Cillero🇪🇸
In the present work we study the production of vector resonances at the LHC by means of the vector boson scattering $W Z \to W Z$ and explore the sensitivities to these resonances for the expected future LHC luminosities. We are assuming that these vector resonances are generated dynamically from the self interactions of the longitudinal gauge bosons, $W_{L}$ and $Z_{L}$ , and work under the framework of the electroweak chiral Lagrangian to describe in a model independent way the supposedly strong dynamics of these modes. The properties of the vector resonances, mass, width and couplings to the $W$ and $Z$ gauge bosons are derived from the inverse amplitude method approach. We implement all these features into a single model, the IAM-MC, adapted for MonteCarlo, built in a Lagrangian language in terms of the electroweak chiral Lagrangian and a chiral Lagrangian for the vector resonances, which mimics the resonant behavior of the IAM and provides unitary amplitudes. The model has been implemented in MadGraph, allowing us to perform a realistic study of the signal versus background events at the LHC. In particular, we have focused our study on the $pp \to W Z j j$ type of events, discussing first on the potential of the hadronic and semileptonic channels of the final $W Z$ , and next exploring in more detail the clearest signals. These are provided by the leptonic decays of the gauge bosons, leading to a final state with $ℓ_{1}^{+} ℓ_{1}^{-} ℓ_{2}^{+} ν j j$ , $ℓ = e, μ$ , having a very distinctive signature, and showing clearly the emergence of the resonances with masses in the range of 1.5-2.5 TeV, which we have explored.
hep-phJHEP(2017)·50 citations
18*
US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report
Marco Battaglieri🇮🇹 · Alberto Belloni🇺🇸 · Aaron Chou🇺🇸 · Priscilla Cushman🇺🇸 · Bertrand Echenard🇺🇸 · Rouven Essig🇺🇸 · Juan Estrada🇺🇸 · Jonathan L. Feng🇺🇸 · Brenna Flaugher🇺🇸 · Patrick J. Fox🇺🇸 · Peter Graham🇺🇸 · Carter Hall🇺🇸 and 239 other authors
This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.
hep-phastro-ph.COhep-ex948 citations
19*
Constraints on vector resonances from a strong Higgs sector
A. E. Cárcamo Hernández🇨🇱 · Bastián Díaz Sáez🇨🇱 · Claudio O. Dib🇨🇱 · Alfonso Zerwekh🇨🇱
We consider a scenario of a composite Higgs arising from a strong sector. We assume that the lowest lying composite states are the Higgs scalar doublet and a massive vector triplet, whose dynamics below the compositeness scale are described in terms of an effective Lagrangian. Electroweak symmetry breaking takes place through a vacuum expectation value just as in the Standard Model, but with the vector resonances strongly coupled to the Higgs field. We determine the constraints on this scenario imposed by (i) the Higgs diphoton decay rate, (ii) the electroweak precision tests and (iii) searches of heavy resonances at the LHC in the final states $l^{+} l^{-}$ and $l ν_{l}$ ( $l = e, μ$ ), $τ^{+} τ^{-}$ , $j j$ , $t t ˉ$ , $W Z$ , $W W$ , $W H$ and $Z H$ . We find that the heavy vector resonances should have masses that are constrained to be in the range $2.1$ - $3$ TeV. On the other hand, the mixing of the heavy vectors with the Standard Model gauge bosons is constrained to be in the range $tan ϑ \sim 0.1 - 0.3$ , which is consistent with the assumption that the Higgs couples weakly to the Standard sector, even though it couples strongly to the heavy vector resonances.
hep-phPRD(2017)·11 citations
20*
dRGT theory of massive gravity from spontaneous symmetry breaking
Mahdi Torabian🇮🇷
In this note we propose a topological action for a Poincare times diffeomorphism invariant gauge theory. We show that there is Higgs phase where the gauge symmetry is spontaneous broken to a diagonal Lorentz subgroup and gives the Einstein-Hilbert action plus the dRGT potential terms. In this vacuum, there are five (three from Goldstone modes) propagating degrees of freedom which form polarizations of a massive spin 2 particle, an extra healthy heavy scalar (Higgs) mode and no Boulware-Deser ghost mode. We further show that the action can be derived in a limit from a topological de Sitter invariant gauge theory in 4 dimensions.
↳ hep-thgr-qchep-phPLB(2018)·4 citations
21*
Signatures of Compact Halos of Sterile-Neutrino Dark Matter
Florian Kuhnel🇸🇪 · Tommy Ohlsson🇸🇪
We investigate compact halos of sterile-neutrino dark matter and examine observable signatures with respect to neutrino and photon emission. Primarily, we consider two cases: primordial black-hole halos and ultra-compact mini-halos. In both cases, we find that there exists a broad range of possible parameter choices such that detection in the near future with X-ray and gamma-ray telescopes might be well possible. In fact, for energies above $10 TeV$ , the neutrino telescope IceCube would be a splendid detection machine for such macroscopic dark-matter candidates.
↳ astro-ph.COgr-qchep-phPRD(2017)·5 citations
22*
Masses and decay constants of D(s)* and B(s)* mesons with Nf = 2 + 1 + 1 twisted mass fermions
V. Lubicz🇮🇹 · A. Melis🇪🇸 · S. Simula🇮🇹
We present a lattice calculation of the masses and decay constants of $D_{(s)}^{*}$ and $B_{(s)}^{*}$ mesons using the gauge configurations produced by the European Twisted Mass Collaboration (ETMC) with $N_{f} = 2 + 1 + 1$ dynamical quarks at three values of the lattice spacing $a \sim (0.06 - 0.09)$ fm. Pion masses are simulated in the range $M_{π} ≃ (210 - 450)$ MeV, while the strange and charm sea-quark masses are close to their physical values. We compute the ratios of vector to pseudoscalar masses and decay constants for various values of the heavy-quark mass $m_{h}$ in the range $0.7 m_{c}^{phys} ≲ m_{h} ≲ 3 m_{c}^{phys}$ . In order to reach the physical b-quark mass, we exploit the Heavy Quark Effective Theory prediction that, in the static limit of infinite heavy-quark mass, the considered ratios are equal to one. At the physical point our results are: $M_{D^{*}} / M_{D} = 1.0769 (79)$ , $M_{D_{s}^{*}} / M_{D_{s}} = 1.0751 (56)$ , $f_{D^{*}} / f_{D} = 1.078 (36),$ $f_{D_{s}^{*}} / f_{D_{s}} = 1.087 (20)$ , $M_{B^{*}} / M_{B} = 1.0078 (15)$ , $M_{B_{s}^{*}} / M_{B_{s}} = 1.0083 (10)$ , $f_{B^{*}} / f_{B} = 0.958 (22)$ and $f_{B_{s}^{*}} / f_{B_{s}} = 0.974 (10)$ . Combining them with the experimental values of the pseudoscalar meson masses (used as input to fix the quark masses) and the values of the pseudoscalar decay constants calculated by ETMC, we get: $M_{D^{*}} = 2013 (14) MeV$ , $M_{D_{s}^{*}} = 2116 (11) MeV$ , $f_{D^{*}} = 223.5 (8.4) MeV$ , $f_{D_{s}^{*}} = 268.8 (6.6) MeV$ , $M_{B^{*}} = 5320.5 (7.6) MeV$ , $M_{B_{s}^{*}} = 5411.36 (5.3) MeV$ , $f_{B^{*}} = 185.9 (7.2) MeV$ and $f_{B_{s}^{*}} = 223.1 (5.4) MeV$ .
↳ hep-lathep-phPRD(2017)·76 citations
23*
Gravitational wave production from preheating: parameter dependence
Daniel G. Figueroa🇨🇭 · Francisco Torrenti🇪🇸
Parametric resonance is among the most efficient phenomena generating gravitational waves (GWs) in the early Universe. The dynamics of parametric resonance, and hence of the GWs, depend exclusively on the resonance parameter $q$ . The latter is determined by the properties of each scenario: the initial amplitude and potential curvature of the oscillating field, and its coupling to other species. Previous works have only studied the GW production for fixed value(s) of $q$ . We present an analytical derivation of the GW amplitude dependence on $q$ , valid for any scenario, which we confront against numerical results. By running lattice simulations in an expanding grid, we study for a wide range of $q$ values, the production of GWs in post-inflationary preheating scenarios driven by parametric resonance. We present simple fits for the final amplitude and position of the local maxima in the GW spectrum. Our parametrization allows to predict the location and amplitude of the GW background today, for an arbitrary $q$ . The GW signal can be rather large, as $h^{2} Ω_{GW} (f_{p}) ≲ 1 0^{- 11}$ , but it is always peaked at high frequencies $f_{p} ≳ 1 0^{7}$ Hz. We also discuss the case of spectator-field scenarios, where the oscillatory field can be e.g.~a curvaton, or the Standard Model Higgs.
↳ astro-ph.COhep-phJCAP(2017)·129 citations
24*
On the Power Spectrum of Dark Matter Substructure in Strong Gravitational Lenses
Ana Diaz Rivero🇺🇸 · Francis-Yan Cyr-Racine🇺🇸 · Cora Dvorkin🇺🇸
Studying the smallest self-bound dark matter structure in our Universe can yield important clues about the fundamental particle nature of dark matter. Galaxy-scale strong gravitational lensing provides a unique way to detect and characterize dark matter substructures at cosmological distances from the Milky Way. Within the cold dark matter (CDM) paradigm, the number of low-mass subhalos within lens galaxies is expected to be large, implying that their contribution to the lensing convergence field is approximately Gaussian and could thus be described by their power spectrum. We develop here a general formalism to compute from first principles the substructure convergence power spectrum for different populations of dark matter subhalos. As an example, we apply our framework to two distinct subhalo populations: a truncated Navarro-Frenk-White subhalo population motivated by standard CDM, and a truncated cored subhalo population motivated by self-interacting dark matter (SIDM). We study in detail how the subhalo abundance, mass function, internal density profile, and concentration affect the amplitude and shape of the substructure power spectrum. We determine that the power spectrum is mostly sensitive to a specific combination of the subhalo abundance and moments of the mass function, as well as to the average tidal truncation scale of the largest subhalos included in the analysis. Interestingly, we show that the asymptotic slope of the substructure power spectrum at large wave number reflects the internal density profile of the subhalos. In particular, the SIDM power spectrum exhibits a characteristic steepening at large wave number absent in the CDM power spectrum, opening the possibility of using this observable, if at all measurable, to discern between these two scenarios.
↳ astro-ph.COhep-phPRD(2018)·63 citations
25*
Damping of gravitational waves by matter
Gordon Baym🇺🇸 · Subodh P. Patil🇩🇰 · C. J. Pethick🇩🇰
We develop a unified description, via the Boltzmann equation, of damping of gravitational waves by matter, incorporating collisions. We identify two physically distinct damping mechanisms -- collisional and Landau damping. We first consider damping in flat spacetime, and then generalize the results to allow for cosmological expansion. In the first regime, maximal collisional damping of a gravitational wave, independent of the details of the collisions in the matter is, as we show, significant only when its wavelength is comparable to the size of the horizon. Thus damping by intergalactic or interstellar matter for all but primordial gravitational radiation can be neglected. Although collisions in matter lead to a shear viscosity, they also act to erase anisotropic stresses, thus suppressing the damping of gravitational waves. Damping of primordial gravitational waves remains possible. We generalize Weinberg's calculation of gravitational wave damping, now including collisions and particles of finite mass, and interpret the collisionless limit in terms of Landau damping. While Landau damping of gravitational waves cannot occur in flat spacetime, the expansion of the universe allows such damping by spreading the frequency of a gravitational wave of given wavevector.
↳ gr-qcastro-ph.COhep-phhep-thPRD(2017)·53 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.