HEP Phenomenology·hep-ph

Tue·Feb 26, 2019Tuesday·February 26, 2019

41 papers—25 primary·16 cross-listed·reconstructed*

01*
Correlated Electric and Magnetic Dipole Moment in Natural Supersymmetry
Sibo Zheng🇨🇳
In the context of supersymmetry, the two-loop Barr-Zee diagrams which induce CP-violating electric dipole moment of electron due to superpartners simultaneously yield CP-conserving magnetic dipole moment of muon. In this paper, we derive the coherence between the electric and magnetic dipole moments at two-loop level due to stops, charginos or neutralinos-charginos. We also use the coherence to constrain superpartner masses and their CP-violating phases, in the light of recent ACME limit on the electric dipole moment of electron and future experiments about magnetic dipole moment of muon such as Fermilab E989 experiment.
hep-phhep-ex1 citation
02*
An Improved Standard Model Comes with Explicit CPV and Productive of BAU
Chilong Lin🇹🇼
In this manuscript, we present an explicit way to describe the violation of CP symmetry in the standard model (SM) of electroweak interactions. In such a way, complex Cabbibo-Kobayashi-Maskawa (CKM) matrices are achieved which stand for the violation of CP symmetry. At the beginning, two necessary but not sufficient conditions for yielding a complex CKM matrix are stated as criteria. Then we found an interesting condition between the real and imaginary parts of a Hermitian $3 \times 3$ matrix may provide extra relations among its parameters and reduce the number of them from eighteen down to five. In previous investigations, this can be done only down to nine. With another assumption among some of those parameters, the mass-matrix pattern is further simplified so as to be diagonalized analytically and in consequence four matrices which reveal $S_{N}$ symmetries among or between quark generations are obtained. In some of such $S_{N}$ -symmetric cases, the derived CKM matrices are complex which indicate that CP symmetry is violated accordingly. Taking the Jarlskog invariant as an estimate of the CPV strength, the value predicted by this model is orders stronger than the empirical value detected experimentally. However, that happens to fill partly the gap between the cosmologically observed amount of Baryon Asymmetry of the Universe (BAU) and that current Standard Model of particle physics predicts. It also proves the long suspected existence of BAU-productive eras in early universe if some fermions were indistinguishable, i.e., $S_{N}$ -symmetric, under circumstances of extremely high temperatures.
hep-phJ.Mod.Phys.·5 citations
03*
Constraining quark-hadron interface tension in the multi-messenger era
Cheng-Jun Xia🇨🇳 · Toshiki Maruyama🇯🇵 · Nobutoshi Yasutake🇯🇵 · Toshitaka Tatsumi🇯🇵
We study the interface effects of quark-hadron mixed phase in compact stars. The properties of nuclear matter are obtained based on the relativistic-mean-field model. For the quark phase, we adopt perturbation model with running quark masses and coupling constant. At certain choices of parameter sets, it is found that varying the quark-hadron interface tension will have sizable effects on the radii ( $Δ R \approx 600$ m) and tidal deformabilities ( $ΔΛ/Λ \approx 50%$ ) of hybrid stars. These provide possibilities for us to constrain the quark-hadron interface tension with future gravitational wave observations as well as the ongoing NICER mission.
hep-phastro-ph.HEPRD(2019)·43 citations
04*
Stueckelberg Bosons as an Ultralight Dark Matter Candidate
T.R. Govindarajan🇮🇳 · Nikhil Kalyanapuram🇮🇳
In this letter, we propose a new model of fuzzy dark matter based on Stueckelberg theory. Dark matter is treated as a Bose-Einstein condensate of Stueckelberg particles and the resulting cosmological effects are analyzed. Fits are understood for the density and halo sizes of such particles and comparison with existing models is made. Certain attractive properties of the model are demonstrated and lines for future work are laid out.
hep-phgr-qchep-thMod.Phys.Lett.A(2019)·6 citations
05*
Acoustic Rabi oscillations between gravitational quantum states and impact on symmetron dark energy
Gunther Cronenberg🇦🇹 · Philippe Brax🇫🇷 · Hanno Filter🇦🇹 · Peter Geltenbort🇫🇷 · Tobias Jenke🇫🇷 · Guillaume Pignol🇫🇷 · Mario Pitschmann🇦🇹 · Martin Thalhammer🇦🇹 · Hartmut Abele🇦🇹
The standard model of cosmology provides a robust description of the evolution of the universe. Nevertheless, the small magnitude of the vacuum energy is troubling from a theoretical point of view. An appealing resolution to this problem is to introduce additional scalar fields. However, these have so far escaped experimental detection, suggesting some kind of screening mechanism may be at play. Although extensive exclusion regions in parameter space have been established for one screening candidate - chameleon fields - another natural screening mechanism based on spontaneous symmetry breaking has also been proposed, in the form of symmetrons 11. Such fields would change the energy of quantum states of ultra-cold neutrons in the gravitational potential of the earth. Here we demonstrate a spectroscopic approach based on the Rabi resonance method that probes these quantum states with a resolution of E=2 x 10^(-15) eV. This allows us to exclude the symmetron as the origin of Dark Energy for a large volume of the three-dimensional parameter space.
hep-phgr-qcnucl-exNat.Phys.(2018)·89 citations
06*
Two-body charmed baryon decays involving vector meson with $S U (3)$ flavor symmetry
Y.K. Hsiao🇨🇳 · Yu Yao🇨🇳 · H.J. Zhao🇨🇳
We study the two-body anti-triplet charmed baryon decays of $B_{c} \to B_{n} V$ , with $B_{c} = (Ξ_{c}^{0}, - Ξ_{c}^{+}, Λ_{c}^{+})$ and $B_{n} (V)$ the baryon (vector meson) states. Based on the $S U (3)$ flavor symmetry, we predict that $B (Λ_{c}^{+} \to Σ^{+} ρ^{0}, Λ^{0} ρ^{+}) = (0.61 \pm 0.46, 0.74 \pm 0.34) %$ , in agreement with the experimental upper bounds of $(1.7, 6) %$ , respectively. We also find $B (Λ_{c}^{+} \to Ξ^{0} K^{*+}, Σ^{0} K^{*+}, Λ^{0} K^{*+}) = (8.7 \pm 2.7, 1.2 \pm 0.3, 2.0 \pm 0.5) \times 1 0^{- 3}$ to be compatible with the pseudoscalar counterparts. For the doubly Cabibbo-suppressed decay $Ξ_{c}^{+} \to pϕ$ , measured for the first time, we predict its branching ratio to be $(1.5 \pm 0.7) \times 1 0^{- 4}$ , together with $B (Ξ_{c}^{+} \to p K ˉ^{* 0}, Σ^{+} ϕ) = (7.8 \pm 2.2, 1.9 \pm 0.9) \times 1 0^{- 3}$ . The $B_{c} \to B_{n} V$ decays with $B ≃ O (1 0^{- 4} - 1 0^{- 3})$ are accessible to the BESIII, BELLEII and LHCb experiments.
hep-phPLB(2019)·39 citations
07*
Octet baryon electromagnetic form factor double ratios $(G_{E}^{*} / G_{M}^{*}) / (G_{E} / G_{M})$ in a nuclear medium
G. Ramalho🇧🇷 · J.P.B.C. de Melo🇧🇷 · K. Tsushima🇧🇷
The ratios of the baryon electric ( $G_{E}$ ) to magnetic ( $G_{M}$ ) form factors, $G_{E} / G_{M}$ , can provide us with important information on the structure of baryons in vacuum as demonstrated in recent studies for the proton and neutron systems. It has been argued that the corresponding in-medium ratios, $G_{E}^{*} / G_{M}^{*}$ , can also provide useful information on the electromagnetic structure of baryons in a nuclear medium. Although the ratios may not be measured directly in experiments except for the proton at present, the double ratios $(G_{E}^{*} / G_{M}^{*}) / (G_{E} / G_{M})$ can be directly related to the polarization-transfer measurements of bound baryons. In the present work we estimate, for the first time, the double ratios $(G_{E}^{*} / G_{M}^{*}) / (G_{E} / G_{M})$ for all the members of octet baryons in symmetric nuclear matter in the range $Q^{2} = 0$ --3 GeV $^{2}$ , where $Q^{2} = - q^{2}$ with $q$ being the four-momentum transfer.
hep-phhep-exnucl-exnucl-thPRD(2019)·16 citations
08*
Predicting neutrino oscillations with "bi-large" lepton mixing matrices
Peng Chen🇨🇳 · Gui-Jun Ding🇨🇳 · Rahul Srivastava🇪🇸 · José W. F. Valle🇪🇸
We propose two schemes for the lepton mixing matrix $U = U_{l}^{†} U_{ν}$ , where $U = U_{l}$ refers to the charged sector, and $U_{ν}$ denotes the neutrino diagonalization matrix. We assume $U_{ν}$ to be CP conserving and its three angles to be connected with the Cabibbo angle in a simple manner. CP violation arises solely from the $U_{l}$ , assumed to have the CKM form, $U_{l} ≃ V_{CKM}$ , suggested by unification. Oscillation parameters depend on a single parameter, leading to narrow ranges for the "solar" and "accelerator" angles $θ_{12}$ and $θ_{23}$ , as well as for the CP phase, predicted as $δ_{CP} \sim 1.3 π$ .
hep-phPLB(2019)·12 citations
09*
Comment on "Neutron lifetime and dark decay of the neutron and hydrogen''
Bartosz Fornal🇺🇸 · Benjamin Grinstein🇺🇸
The manuscript by Berezhiani (arXiv:1812.11089) proposes a model that has the neutron decaying into a mirror neutron with a branching fraction of 1%, alleviating the tension between neutron lifetime measurements in beam vs bottle experiments. We show that the model as proposed is inconsistent with experiment. Variations of the model may work at the expense of extreme breaking of the $Z_{2}$ symmetry between the Standard Model and its mirror copy.
hep-ph3 citations
10*
Positivity constraints on aQGC: carving out the physical parameter space
Qi Bi🇨🇳 · Cen Zhang🇨🇳 · Shuang-Yong Zhou🇨🇳
Searching for deviations in quartic gauge boson couplings (QGCs) is one of the main goals of the electroweak program at the LHC. We consider positivity bounds adapted to the Standard Model, and show that a set of positivity constraints on 18 anomalous QGC couplings can be derived, by requiring that the vector boson scattering amplitudes of specific channels and polarisations satisfy the fundamental principles of quantum field theory. We explicitly solve the positivity inequalities to remove their dependence on the polarisations of the external particles, and obtain 19 linear inequalities, 3 quadratic inequalities, and 1 quartic inequality that only involve the QGC parameters and the weak angle. These inequalities constrain the possible directions in which deviations from the standard QGC can occur, and can be used to guide future experimental searches. We study the morphology of the positivity bounds in the parameter space, and find that the allowed parameter space is carved out by the intersection of pyramids, prisms, and (approximately) cones. Altogether, they reduce the volume of the allowed parameter space to only 2.1% of the total. We also show the bounds for some benchmark cases, where one, two, or three operators, respectively, are turned on at a time, so as to facilitate a quick comparison with the experimental results.
hep-phhep-exJHEP(2019)·117 citations
11*
Coherent elastic neutrino-nucleus scattering as a precision test for the Standard Model and beyond: the COHERENT proposal case
O. G. Miranda🇲🇽 · G. Sanchez Garcia🇲🇽 · O. Sanders🇲🇽
Several experimental proposals expect to confirm the recent measurement of the coherent elastic neutrino-nucleus scattering (CEvNS). Motivated in particular by the next generation experiments of the COHERENT collaboration, we study their sensitivity to different tests of the Standard Model and beyond. We analyze the resolution that can be achieved by each future proposed detector in the measurement of the weak mixing angle; we also perform similar analysis in the context of Non-Standard Interaction (NSI) and in the case of an oscillation into a sterile neutrino state. We show that the future perspectives are interesting for these types of new physics searches.
hep-phAdv.High Energy Phys.(2019)·47 citations
12*
Kinematic distributions of the $η_{c}$ photoproduction in $e p$ collisions within the nonrelativistic QCD framework
Hong-Fei Zhang (College of Big Data Statistics, Guizhou University of Finance and Economics, Guiyang, China)🇨🇳 · Yu Feng (Department of Physics, College of Basic Medical Sciences, Army Medical University, Chongqing, China)🇨🇳 · Wen-Long Sang (School of Physical Science and Technology, Southwest University, Chongqing, China)🇨🇳 · Yu-Peng Yan (School of Physics and Center of Excellence in High Energy Physics and Astrophysics, Suranaree University of Technology, Nakhon Ratchasima, Thailand)🇹🇭
We study the $η_{c}$ photoproduction in $e p$ collisions in this paper. The short-distance coefficients for $c c ˉ (^{1} S_{0}^{[1]})$ , $c c ˉ (^{1} S_{0}^{[8]})$ , $c c ˉ (^{3} S_{1}^{[8]})$ , and $c c ˉ (^{1} P_{1}^{[8]})$ photoproductions are evaluated at leading order in $α_{s}$ expansion, where the color-singlet contribution is achieved for the first time. We have carefully analyzed different kinematic distributions of the cross sections and found that the color-singlet contribution is considerably suppressed comparing with the color-octet parts. This feature renders the $η_{c}$ photoproduction process an ideal laboratory to test the color-octet mechanism in nonrelativistic QCD. By taking different sets of long-distance matrix elements, we have observed some apparently distinguishable predictions, which can be utilized to scrutinize the validity of these matrix elements.
hep-phPRD(2019)·4 citations
13*
A Minimal SU(5) SuperGUT in Pure Gravity Mediation
Jason L. Evans🇰🇷 · Natsumi Nagata🇯🇵 · Keith A. Olive🇺🇸
The lack of evidence for low-scale supersymmetry suggests that the scale of supersymmetry breaking may be higher than originally anticipated. However, there remain many motivations for supersymmetry including gauge coupling unification and a stable dark matter candidate. Models like pure gravity mediation (PGM) evade LHC searches while still providing a good dark matter candidate and gauge coupling unification. Here, we study the effects of PGM if the input boundary conditions for soft supersymmetry breaking masses are pushed beyond the unification scale and higher dimensional operators are included. The added running beyond the unification scale opens up the parameter space by relaxing the constraints on $tan β$ . If higher dimensional operators involving the SU(5) adjoint Higgs are included, the mass of the heavy gauge bosons of SU(5) can be suppressed leading to proton decay, $p \to π^{0} e^{+}$ , that is within reach of future experiments. Higher dimensional operators involving the supersymmetry breaking field can generate additional contributions to the A- and B-terms of order $m_{3/2}$ . The threshold effects involving these A- and B-terms significantly impact the masses of the gauginos and can lead to a bino LSP. In some regions of parameter space the bino can be degenerate with the wino or gluino and give an acceptable dark matter relic density.
hep-phEPJC(2019)·20 citations
14*
Studies on photo- and electro-productions of $Λ (1405)$ via $γ^{(*)} p \to K^{*+} π^{0} Σ^{0}$
Seung-il Nam🇰🇷 · Atsushi Hosaka🇯🇵
We study the photo- and electro-productions of the vector kaon off the proton, i.e., $γ^{(*)} p \to K^{*+} π^{0} Σ^{0}$ , and investigate the line shape of the $π^{0} Σ^{0}$ invariant mass in an effective Lagrangian approach with the inclusion of a $K^{*} N Λ^{*}$ interaction. Relevant electromagnetic form factors for the neutral hyperons and charged strange mesons are constructed by considering experimental and theoretical information. We find that the $Λ^{*}$ peak is clearly observed for the photo- and electro-productions with the finite $K^{*} N Λ^{*}$ interaction, whereas the clear peak signals survive only for the electro-production, when we ignore the interaction. These different behaviors can be understood by different $Q^{2}$ dependences in the $K^{*}$ electromagnetic and $K^{*} \to γ K$ transition form factors. We suggest a photon-polarization asymmetry $Σ$ to extract information of the $K^{*} N Λ^{*}$ interaction. It turns out that $Σ$ near the $Λ^{*}$ peak region becomes negative with a finite $K^{*} N Λ^{*}$ interaction while positive without it for $Q^{2} = 0$ , due to the different naturalities of $K$ and $K^{*}$ exchanges. For $Q^{2} \neq = 0$ , we observe more obvious signals in the peak region due to the additional contribution of the longitudinal virtual photon for $Λ^{*}$ .
hep-phhep-exnucl-exnucl-thPRC(2019)·0 citations
15*
Probing DAMA/LIBRA in the full parameter space of WIMP effective models of inelastic scattering
Sunghyun Kang🇰🇷 · Stefano Scopel🇰🇷 · Gaurav Tomar (Sogang U.)🇰🇷
We discuss the compatibility of the combined annual modulation effect measured by DAMA/LIBRA-phase1 and DAMA/LIBRA-phase2 with an explanation in terms of inelastic scattering events induced by the most general Galilean-invariant effective contact interaction of a Weakly Interacting Massive Particle (WIMP) dark matter particle of spin 0, 1/2 or 1. We take into account all the possible interferences among operators by studying the intersections among the ellipsoidal surfaces of constant signal of DAMA and other experiments in the space of the coupling constants of the effective theory. In our analysis we assume a standard Maxwellian velocity distribution in the Galaxy. We find that, compared to the elastic case, inelastic scattering partially relieves but does not eliminate the existing tension between the DAMA effect and the constraints from the null results of other experiments. Such tension is very large in all the parameter space with the exception of a small region for WIMP mass $m_{χ} ≃$ 10 GeV and mass splitting $δ ≳$ 20 keV, where it is partially, but not completely relieved. In such region the bounds from fluorine targets are evaded in a kinematic way because the minimal WIMP incoming speed required to trigger upscatters off fluorine exceeds the maximal WIMP velocity in the Galaxy, or is very close to it. As a consequence, we also find that the residual tension between DAMA and other results is more sensitive on the astrophysical parameters compared to the elastic case. We find that the configurations with the smallest tension can produce enough yearly modulation in some of the DAMA bins in compliance with the constraints from other experiments, but the ensuing shape of the modulation spectrum is too steep compared to the measured one. For such configurations the recent COSINE-100 bound is evaded in a natural way due to their large expected modulation fractions.
hep-phPRD(2019)·30 citations
16*
Color reconnection as a possible mechanism of intermittency in the emission spectra of charged particles in PYTHIA-generated high-multiplicity $pp$ collisions at energies available at the CERN Large Hadron Collider
Buddhadeb Bhattacharjee🇮🇳 · Pranjal Sarma🇮🇳
Nonstatistical fluctuation in pseudorapidity ( $η$ ), azimuthal ( $ϕ$ ), and pseudorapidity-azimuthal ( $η - ϕ$ ) distribution spectra of primary particles of PYTHIA Monash (default) generated $pp$ events at $s =$ 2.76, 7, and 13 TeV have been studied using the scaled factorial moments technique. A weak intermittent type of emission could be realized for minimum-bias (MB) $pp$ events in $χ (η - ϕ)$ space and a much stronger intermittency could be observed in high-multiplicity (HM) $pp$ events in all $χ (η)$ , $χ (ϕ)$ , and $χ (η - ϕ)$ spaces at all the studied energies. For HM $pp$ events, at a particular energy, the intermittency index $α_{q}$ is found to be largest in two-dimensional $χ (η - ϕ)$ space and least in $χ (η)$ space, and no center of mass energy dependence of $α_{q}$ could be observed. The anomalous dimensions $d_{q}$ are observed to be increased with the order of the moment $q$ , suggesting a multifractal nature of the emission spectra of various studied events. While, the coefficient $λ_{q}$ is found to decrease monotonically with the order of the moment $q$ for two-dimensional analysis of MB $pp$ events as well as for one-dimensional analysis of HM $pp$ events, a clear minimum in $λ_{q}$ values could be observed from the two-dimensional HM $pp$ data analysis. For PYTHIA Monash generated sets of data, the strength of the intermittency is found to vary significantly with the variation of the strength of the color reconnection (CR) parameter, i.e., reconnection range RR, for RR = 0.0, 1.8 and 3.0, thereby, establishing a strong connection between the CR mechanism and the observed intermittent type of emission of primary charged particles of the studied high-multiplicity $pp$ events.
hep-phPRC(2019)·27 citations
17*
Twist-2 Pseudoscalar and Vector Meson Distribution Amplitudes in Light-Front Quark Model with Exponential-type Confining Potential
Nisha Dhiman🇮🇳 · Harleen Dahiya🇮🇳 · Chueng-Ryong Ji🇺🇸 · Ho-Meoyng Choi🇰🇷
We study the twist-2 distribution amplitudes (DAs) and the decay constants of pseudoscalar light ( $π$ , $K$ ) and heavy ( $D$ , $D_{s}$ , $B$ , $B_{s}$ ) mesons as well as the longitudinally and transversely polarized vector light ( $ρ$ , $K^{*}$ ) and heavy ( $D^{*}$ , $D_{s}^{*}$ , $B^{*}$ , $B_{s}^{*}$ ) mesons in the light-front quark model with the Coulomb plus exponential-type confining potential $V_{exp} = a + b e^{α r}$ in addition to the hyperfine interaction. We first compute the mass spectra of ground state pseudoscalar and vector light and heavy mesons and fix the model parameters necessary for the analysis, applying the variational principle with the trial wave function up to the first three lowest order harmonic oscillator (HO) wave functions $Φ (x, k_{⊥}) = \sum_{n = 1}^{3} c_{n} ϕ_{n S}$ . We then obtain the numerical results for the corresponding decay constants of light and heavy mesons. We estimate the DAs, analyze their variation as a function of momentum fraction and compute the first six $ξ$ -moments of the $B$ and $D$ mesons as well. We compare our results with the available experimental data as well as with the other theoretical model predictions.
hep-phnucl-thPRD(2019)·35 citations
18*
Radial and orbital Regge trajectories in heavy quarkonia
A.M. Badalian B.L.G. Bakker
The spectra of heavy quarkonia are studied in two approaches: with the use of the Afonin-Pusenkov representation of the Regge trajectory for the squared excitation energy $E^{2} (n l)$ (ERT), and using the relativistic Hamiltonian with the universal interaction. The parameters of the ERTs are extracted from experimental mass differences and their values in bottomonium: the intercept $a (b b ˉ) = 0.131$ GeV $^{2}$ , the slope of the orbital ERT $b_{l} (b b ˉ) = 0.50$ \,GeV $^{2}$ , and the slope of the radial ERT, $b_{n} (b b ˉ) = 0.724$ \,GeV $^{2}$ , appear to be smaller than those in charmonium, where $a (c c ˉ) = 0.381$ \,GeV $^{2}$ , $b_{l} (c c ˉ) = 0.686$ \,GeV $^{2}$ , and the radial slope $b_{n} (c c ˉ) = 1.074$ \,GeV $^{2}$ , which value is close to that in light mesons, $b_{n} (q q ˉ) = 1.1 (1)$ \,GeV $^{2}$ . For the resonances above the $D D ˉ$ threshold the masses of the $χ_{c 0} (n P)$ with $n = 2, 3, 4$ , equal to 4218\,MeV, 4503\,MeV, 4754\,MeV, are obtained, while above the $B B ˉ$ threshold the resonances $Υ (3^{3} D_{1})$ with the mass 10693\,MeV and $χ_{b 1} (4^{3} P_{1})$ with the mass 10756\,MeV are predicted.
hep-phhep-exPRD(2019)·25 citations
19*
Using an amplitude analysis to measure the photon polarisation in $B \to K π π γ$ decays
Violaine Bellée🇨🇭 · Preema Pais🇨🇭 · Albert Puig Navarro🇨🇭 · Frédéric Blanc🇨🇭 · Olivier Schneider🇨🇭 · Karim Trabelsi🇫🇷 · Giovanni Veneziano🇫🇷
A method is proposed to measure the photon polarisation parameter $λ_{γ}$ in $b \to s γ$ transitions using an amplitude analysis of $B \to K π π γ$ decays. Simplified models of the $K π π$ i system are used to simulate $B^{+} \to K^{+} π^{-} π^{+} γ$ and $B^{0} \to K^{+} π^{-} π^{0}$ decays, validate the amplitude analysis method, and demonstrate the feasibility of a measurement of the $λ_{γ}$ parameter irrespective of the model parameters. Similar sensitivities to $λ_{γ}$ are obtained with both the charged and neutral hadronic systems. In the absence of any background and distortion due to experimental effects, the statistical uncertainty expected from an analysis of $B^{+} \to K^{+} π^{-} π^{+} γ$ decays in an LHCb data set corresponding to an integrated luminosity of $9$ fb $^{- 1}$ is estimated to be $0.009$ . A similar measurement using $B^{0} \to K^{+} π^{-} π^{0}$ decays in a Belle II data sample corresponding to an integrated luminosity of $5$ ab $^{- 1}$ would lead to a statistical uncertainty of $0.018$
hep-phEPJC(2019)·8 citations
20*
Interpretation of the cosmic ray positron and electron excesses with an annihilating-decaying dark matter scenario
Lei Feng🇨🇳 · Zhaofeng Kang🇨🇳 · Qiang Yuan🇨🇳 · Peng-Fei Yin🇨🇳 · Yi-Zhong Fan🇨🇳
The precise measurements of energy spectra of cosmic ray positrons and/or electrons by recent experiments show clear excesses above 10 GeV. Moreover, a potential sharp spectral feature was suggested by the Dark Matter Particle Explorer (DAMPE) data. These results inspire quite a number of discussions on the connection with either the annihilation/decay of dark matter (DM) or the astrophysical origins. Here we discuss a DM scenario in which DM particles could annihilate and decay into standard model particle pairs simultaneously. In this model, the peak structure is due to the DM annihilation in a nearby subhalo and the broad positron/electron excesses are due to the decay of DM in the Milky Way. This model can reasonably explain the DAMPE and AMS-02 data of the total $e^{+} e^{-}$ spectra and the positron fraction, with model parameters being consistent with existing constraints. A simple realization of such a DM model is the spin-1 vector DM model.
hep-phJCAP(2020)·10 citations
21*
Core-corona effect in hadron collisions and muon production in air showers
Sebastian Baur🇧🇪 · Hans Dembinski🇩🇪 · Matias Perlin🇩🇪 · Tanguy Pierog🇩🇪 · Ralf Ulrich🇩🇪 · Klaus Werner🇫🇷
It is very well known that the fraction of energy in a hadron collision going into electromagnetic particles (electrons and photons, including those from decays) has a large impact on the number of muons produced in air shower cascades. Recent measurements at the LHC confirm features that can be linked to a mixture of different underlying particle production mechanisms such as a collective statistical hadronization (core) in addition to the expected string fragmentation (corona). Since the two mechanisms have a different electromagnetic energy fraction, we present a possible connection between statistical hadronization in hadron collisions and muon production in air showers. Using a novel approach, we demonstrate that the core-corona effect as observed at the LHC could be part of the solution for the lack of muon production in simulations of high energy cosmic rays. To probe this hypothesis, we study hadronization in high energy hadron collisions using calorimetric information over a large range of pseudorapidity in combination with the multiplicity of central tracks. As an experimental observable, we propose the production of energy in electromagnetic particles versus hadrons, as a function of pseudorapidity and central charged particle multiplicity.
hep-phPRD(2023)·63 citations
22*
On the origin of the $Y (4260)$
Susana Coito🇵🇱 · Francesco Giacosa🇵🇱
We study the relation between the $ψ (4160)$ and the $Y (4260)$ within an unitarized effective Lagrangian approach. The $Y (4260)$ arises as a manifestation of the $ψ (4160)$ , when a loop-driven decay of the type $ψ (4160) \to D_{s}^{*} D ˉ_{s}^{*} \to J / ψ f_{0} (980)$ is enhanced by the proximity of the pole, corresponding to the $ψ (4160)$ , to the \emph{almost} closed $D_{s}^{*} D ˉ_{s}^{*}$ decay channel. Other $f_{0}$ resonances that may add a non-negligible contribution, by the same mechanism, are not included for simplicity, but they are not expected to change the main conclusion. Within this picture, the $Y (4260)$ is not, therefore, an independent resonance, but rather a variation of the $ψ (4160)$ , which also explains why it is not seen in OZI-allowed decay channels in the experiment.
hep-phActa Phys.Polon.B(2020)·11 citations
23*
A Precise Determination of (Anti)neutrino Fluxes with (Anti)neutrino-Hydrogen Interactions
H. Duyang🇺🇸 · B. Guo🇺🇸 · S.R. Mishra🇺🇸 · R. Petti🇺🇸
We present a novel method to accurately determine the flux of neutrinos and antineutrinos, one of the dominant systematic uncertainty affecting current and future long-baseline neutrino experiments, as well as precision neutrino scattering experiment. Using exclusive topologies in $ν (ν ˉ)$ -hydrogen interactions, $ν_{μ} p \to μ^{-} p π^{+}$ , $ν ˉ_{μ} p \to μ^{+} p π^{-}$ , and $ν ˉ_{μ} p \to μ^{+} n$ with small hadronic energy, we achieve an overall accuracy on the relative fluxes better than 1\% in the energy range covering most of the available flux. Since we cannot rely on simulations nor model corrections at this level of precision, we present techniques to constrain all relevant systematic uncertainties using data themselves. The method can be implemented using the approach we recently proposed to collect high statistics samples of $ν (ν ˉ)$ -hydrogen interactions in a low-density and high-resolution detector, which could serve as part of the near detector complex in a long-baseline neutrino experiment, as well as a dedicated beam monitoring detector.
hep-phhep-exnucl-exnucl-th+1PLB(2019)·32 citations
24*
N = 5, 6, 7, 8: Nested hypothesis tests and truncation dependence of $∣ V_{c b} ∣$
Florian U. Bernlochner🇩🇪 · Zoltan Ligeti🇺🇸 · Dean J. Robinson🇺🇸
The determination of $∣ V_{c b} ∣$ from exclusive semileptonic $B \to D^{*} ℓ ν$ decays is sensitive to the choice of form factor parametrization. Larger $∣ V_{c b} ∣$ values are obtained fitting the BGL versus the CLN parametrization to recent Belle measurements. For the BGL parametrization, published fits use different numbers of parameters. We propose a method based on nested hypothesis tests to determine the optimal number of BGL parameters to fit the data, and find that six parameters are optimal to fit the Belle tagged and unfolded measurement. We further explore the differences between fits that use different numbers of parameters. The fits which yield $∣ V_{c b} ∣$ values in better agreement with determinations from inclusive semileptonic decays, tend to exhibit tensions with heavy quark symmetry expectations. These have to be resolved before the determinations of $∣ V_{c b} ∣$ from exclusive and inclusive decays can be considered understood.
hep-phPRD(2019)·46 citations
25*
Tensors for tending to tensions in $τ$ decays
Amol Dighe🇮🇳 · Subhajit Ghosh🇮🇳 · Girish Kumar🇮🇳 · Tuhin S. Roy🇮🇳
We propose a manifestly gauge invariant effective tensor operator that can account for the $C P$ asymmetry anomaly in $τ$ decays, contrary to the claim made in literature. Additionally, this operator can also help in resolving the long-standing discrepancy in the value of $V_{u s}$ extracted from inclusive $τ$ decays. By construction, the operator evades bounds from neutron electric dipole moment, while keeping the extraction of $V_{u s}$ from exclusive $τ$ decays unaffected. We explicitly provide a renormalizable model of flavor symmetries that yields the desired effective tensor operator.
hep-ph17 citations
26*
Dynamical enhancement of nonparaxial effects in the electromagnetic field of a vortex electron
Dmitry Karlovets🇷🇺
A quantum state of an electron influences its electromagnetic field. If a spatial profile of the electron wave packet is not Gaussian, the particle may acquire additional intrinsic multipole moments, which alter its field, especially at small distances. Here the fields of a vortex electron with orbital angular momentum $ℓ$ are obtained in a form of a multipole expansion with an electric quadrupole term kept by using the generalized (non-paraxial) Laguerre-Gaussian beams. The quadrupole contribution arises beyond a paraxial approximation, is linearly enhanced for highly twisted packets with $∣ ℓ ∣ ≫ 1$ , and can be important for the interactions of twisted beams with bulk matter and artificial structures. Moreover, this term results in an azimuthal asymmetry of the magnetic field in a rest frame of the electron, which appears thanks to the spreading of the packet with time. Thus, somewhat contrary to physical intuition, the spreading may enhance non-paraxial phenomena. For the available electron beams, this asymmetry can in principle be reliably detected, which would be experimental evidence of a non-paraxial effect with the vortex electrons.
↳ quant-phhep-phphysics.atom-phphysics.opticsPRA(2019)·10 citations
27*
Charm-Baryon Production in Proton-Proton Collisions
Min He🇨🇳 · Ralf Rapp🇺🇸
Recent measurements of charm-baryon production in proton-proton collisions at the LHC have found a surprisingly large yield relative to those of $D$ -mesons. We propose that this observation can be explained by the statistical hadronization model (SHM), by employing a largely augmented set of charm-baryon states beyond the current listings of the particle data group. We estimate the additional states using guidance from the relativistic quark model and from lattice QCD. Using charm- and strange-quark fugacity factors to account for the well-known suppression of heavy flavor in elementary collisions, we compute the yields and spectra of $D$ , $D_{s}$ and $Λ_{c}$ hadrons in proton-proton collisions at $s = 5$ \,TeV. Our main finding is that the enhanced feeddown from excited charm baryons can account for the $Λ_{c} / D^{0}$ ratio measured by ALICE at midrapidity, with some caveat for the forward-rapidity LHCb data. Furthermore, assuming independent fragmentation of charm quarks but with the hadronic ratios fixed by the SHM, the measured transverse-momentum ( $p_{T}$ ) spectra of $D$ -mesons and $Λ_{c}$ can also be described; in particular, the low- $p_{T}$ enhancement in the observed $Λ_{c} / D^{0}$ ratio is attributed to the enhanced feeddown from "missing" charm-baryon states. We comment on the implications of these findings for measurements of $D_{s}$ and $Λ_{c}$ in heavy-ion collisions.
↳ nucl-thhep-exhep-phnucl-exPLB(2019)·173 citations
28*
Event Shape Sorting: prospects and femtoscopy applications
Jakub Cimerman🇨🇿 · Boris Tomášik🇸🇰
We demonstrate the use of Event Shape Sorting in femtoscopy. The method allows to select events with similar distributions if hadrons in azimuthal angle. We show that also their correlation radii exhibit interesting dependence on azimuthal angle with anisotropies of different orders visible at the same time. We further demonstrate such features of the hadron distribution which can be hardly recognised by Event Shape Engineering, but shows up in Event Shape Sorting. Finally, the influence of statistical fluctuations on sorting is investigated.
↳ nucl-thhep-phnucl-exPoS(2019)·0 citations
29*
RMF models with $σ$ -scaled hadron masses and couplings for description of heavy-ion collisions below 2A GeV
K.A. Maslov🇷🇺 · D.N. Voskresensky🇷🇺
Within the relativistic mean-field framework with hadron masses and coupling constants dependent on the mean scalar field we study properties of nuclear matter at finite temperatures, baryon densities and isospin asymmetries relevant for heavy-ion collisions at laboratory energies below 2 $A$ GeV. Previously constructed (KVORcut-based and MKVOR-based) models for the description of the cold hadron matter, which differ mainly by the density dependence of the nucleon effective mass and symmetry energy, are extended for finite temperatures. The baryon equation of state, which includes nucleons and $Δ$ resonances is supplemented by the contribution of the pion gas described either by the vacuum dispersion relation or with taking into account the $s$ -wave pion-baryon interaction. Distribution of the charge between components is found. Thermodynamical characteristics on $T - n$ plane are considered. The energy-density and entropy-density isotherms are constructed and a dynamical trajectory of the hadron system formed in heavy-ion collisions is described. The effects of taking into account the $Δ$ isobars and the $s$ -wave pion-nucleon interaction on pion differential cross sections, pion to proton and $π^{-} / π^{+}$ ratios are studied. The liquid-gas first-order phase transition is studied within the same models in isospin-symmetric and asymmetric systems. We demonstrate that our models yield thermodynamic characteristics of the phase transition compatible with available experimental results. In addition, we discuss the scaled variance of baryon and electric charge in the phase transition region. Effect of the non-zero surface tension on spatial redistribution of the electric charge is considered for a possible application to heavy-ion collisions at low energies.
↳ nucl-thastro-ph.HEhep-phEPJA(2019)·6 citations
30*
Spin polarization of $Λ$ hyperons in $e^{+} e^{-} \to Λ Λ ˉ$ at BESIII
Cui Li🇸🇪 · Karin Schoenning (for the BESIII Collaboration)🇸🇪
The BESIII collaboration here reports the first observation of polarized $Λ$ and $Λ ˉ$ hyperons produced in two different processes: i) the resonant $e^{+} e^{-} \to J / ψ \to Λ Λ ˉ$ , using a data sample of 1.31 $\times$ 10 $^{9}$ $J / ψ$ events and ii) the non-resonant $e^{+} e^{-} \to γ^{*} \to Λ Λ ˉ$ , using a 66.9 pb $^{- 1}$ data sample collected at $s =$ 2.396 GeV. In $e^{+} e^{-} \to J / ψ \to Λ Λ ˉ$ , the phase between the electric and the magnetic amplitude is measured for the first time to be $42. 3^{o} \pm 0. 6^{o} \pm 0. 5^{o}$ . The multi-dimensional analysis enables a model-independent measurement of the decay parameters for $Λ \to p π^{-}$ ( $α_{-}$ ), $Λ ˉ \to p ˉ π^{+}$ ( $α_{+}$ ) and $Λ ˉ \to n ˉ π^{0}$ ( $α ˉ_{0}$ ). The obtained value $α_{-} = 0.750 \pm 0.009 \pm 0.004$ differs with ~5 $σ$ from the PDG value. This value, together with the measurement $α_{+} = - 0.758 \pm 0.010 \pm 0.007$ allow for the most precise test of CP violation in $Λ$ decays so far: $A_{C P} = (α_{-} + α_{+}) / (α_{-} - α_{+})$ of $- 0.006 \pm 0.012 \pm 0.007$ . The decay asymmetry $α ˉ_{0} = - 0.692 \pm 0.016 \pm 0.006$ is measured for the first time. The $e^{+} e^{-} \to Λ Λ ˉ$ reaction at $s =$ 2.396 GeV enables a first complete measurement of the time-like electric and magnetic form factor of any baryon, of the modulus of the ratio $R = ∣ G_{E} / G_{M} ∣$ and of the relative phase $ΔΦ = Φ_{E} - Φ_{M}$ . With the decay asymmetry parameters from the $J / ψ$ data, the obtained values are $R = 0.96 \pm 0.14 \pm 0.02$ and $ΔΦ = 3 7^{o} \pm 1 2^{o} \pm 6^{o}$ . In addition, the cross section has been measured with unprecedented precision to be $σ = 119.0 \pm 5.3 \pm 5.1$ pb, which corresponds to an effective form factor of $∣ G ∣ = 0.123 \pm 0.003 \pm 0.003$ .
↳ hep-exhep-phJ.Phys.Conf.Ser.(2019)·0 citations
31*
Real-time quantum dynamics, path integrals and the method of thimbles
Zong-Gang Mou🇳🇴 · Paul M. Saffin🇬🇧 · Anders Tranberg🇳🇴 · Simon Woodward🇬🇧
Direct numerical evaluation of the real-time path integral has a well-known sign problem that makes convergence exponentially slow. One promising remedy is to use Picard-Lefschetz theory to flow the domain of the field variables into the complex plane, where the integral is better behaved. By Cauchy's theorem, the final value of the path integral is unchanged. Previous analyses have considered the case of real scalar fields in thermal equilibrium, employing a closed Schwinger-Keldysh time contour, allowing the evaluation of the full quantum correlation functions. Here we extend the analysis by not requiring a closed time path, instead allowing for an initial density matrix for out-of-equilibrium initial value problems. We are able to explicitly implement Gaussian initial conditions, and by separating the initial time and the later times into a two-step Monte-Carlo sampling, we are able to avoid the phenomenon of multiple thimbles. In fact, there exists one and only one thimble for each sample member of the initial density matrix. We demonstrate the approach through explicitly computing the real-time propagator for an interacting scalar in 0+1 dimensions, and find very good convergence allowing for comparison with perturbation theory and the classical-statistical approximation to real-time dynamics.
↳ hep-lathep-phhep-thJHEP(2019)·35 citations
32*
Anomaly-induced transport phenomena from the imaginary-time formalism
Masaru Hongo🇯🇵 · Yoshimasa Hidaka🇯🇵
A derivation of the anomaly-induced transport phenomena---the chiral magnetic/vortical effect---is revisited based on the imaginary-time formalism of quantum field theory. Considering the simplest anomalous system composed of a single Weyl fermion, we provide two derivations: perturbative (one-loop) evaluation of the anomalous transport coefficient, and the anomaly matching for the local thermodynamic functional.
↳ hep-thcond-mat.mes-hallcond-mat.stat-mechhep-ph+1Particles(2019)·13 citations
33*
Initial state radiation correction and its effect to data-taking scheme for $σ^{B} (e^{+} e^{-} \to Z H)$ measurement
Shuang Han🇨🇳 · Gang Li🇨🇳 · Xiang Zhou🇨🇳 · Quan-Lin Jie🇨🇳
The measurement of Born cross section of $e^{+} e^{-} \to Z H$ process is one of the major goals of the future Circular Electron Positron Collider, which may reach a precision of 0.5%. Such unprecedented precision must be guaranteed by both theoretical and experimental sides, such as the calculations of high order corrections, the knowledge of the $σ^{B} (e^{+} e^{-} \to Z H)$ line shape. The uncertainty of radiative correction factor due to lack of knowledge of the $σ^{B} (e^{+} e^{-} \to Z H)$ line shape is evaluated in this work. Therefore, the dedicated data-taking schemes are proposed in order to precisely calculate the ISR correction factor.
↳ hep-exhep-phInt.J.Mod.Phys.A(2019)·0 citations
34*
Longitudinal conductivity of hot magnetized collisional QCD medium in the inhomogeneous electric field
Manu Kurian🇮🇳 · Vinod Chandra🇮🇳
The longitudinal current density induced by the inhomogeneous electric field in the hot magnetized quark-gluon plasma has been investigated and utilized in obtaining the conductivity of the medium. The analysis has been done in the regime where inhomogeneity of the field is small so that the collision effect could be significant. The modeling of the QCD medium is based on a quasiparticle description where the medium effects have been encoded in the effective quarks, antiquarks and gluons. The temperature dependence of the linear longitudinal current density (in terms of the electric field) and the additional components of current density due to the inhomogeneity of electric field (in terms of its derivatives) have been obtained by solving the $(1 + 1) -$ dimensional effective covariant kinetic theory with a proper collision term. The conductivity has been obtained from the current density in the presence of the inhomogeneous field. The collisional aspects of the medium have been captured by including both thermal relaxation approximation and the Bhatnagar-Gross-Krook collision kernels in the analysis. Further, the hot QCD medium effects and higher Landau level contributions to the current density and the conductivity have been investigated. It has been seen that the effects of inhomogeneity of the field and the mean field corrections to the current density and the conductivity are more visible in the temperature regions which are not far from the transition temperature.
↳ nucl-thhep-phPRD(2019)·20 citations
35*
Lattice study of QCD at finite chiral density: topology and confinement
N.Yu. Astrakhantsev🇨🇭 · V.V. Braguta🇷🇺 · A.Yu. Kotov🇷🇺 · D.D. Kuznedelev🇷🇺 · A.A. Nikolaev🇬🇧
In this paper we study the properties of QCD at nonzero chiral density $ρ_{5}$ , which is introduced through chiral chemical potential $μ_{5}$ . The study is performed within lattice simulation of QCD with dynamical rooted staggered fermions. We first check that $ρ_{5}$ is generated at nonzero $μ_{5}$ and in the chiral limit observe $ρ_{5} \sim Λ_{QC D}^{2} μ_{5}$ . We also test the possible connection between confinement and topological fluctuations. To this end, we measured the topological susceptibility $χ_{\mbox t o p}$ and string tension $σ$ for various values of $μ_{5}$ . We observed that both string tension and chiral susceptibility grow with $μ_{5}$ and there is a strong correlation between these quantities. We thus conclude that the chiral chemical potential enhances topological fluctuations and that these fluctuations can indeed be closely related to the strength of confinement.
↳ hep-lathep-phhep-thEPJA(2021)·26 citations
36*
Summary of the 2018 CKM working group on semileptonic and leptonic $b$ -hadron decays
Christopher Bouchard🇬🇧 · Lu Cao🇩🇪 · Patrick Owen🇨🇭
A summary of WG II of the CKM 2018 conference on semileptonic and leptonic $b$ -hadron decays is presented. This includes discussions on the CKM matrix element magitudes $∣ V_{u b} ∣$ and $∣ V_{c b} ∣$ , lepton universality tests such as $R (D^{*})$ and leptonic decays. As is usual for semileptonic and leptonic decays, much discussion is devoted towards the interplay between theoretical QCD calculations and the experimental measurements.
↳ hep-exhep-lathep-ph6 citations
37*
Reheating Constraints on Inflaton, Dark Matter: Swampland Conjecture
Md Riajul Haque🇮🇳 · Debaprasad Maity🇮🇳
In this paper, we studied the phenomenological consequences of recently proposed swampland conjecture on the inflationary models though constraints on reheating. If dark matter is assumed to be produced during reheating, the conjecture will provide further constraints on the dark matter parameter space through its current relic abundance. As has been pointed out already and also analyzed in our present paper any successful inflationary scenario is in clear tension with the aforementioned conjecture in its current form. However considering the swampland parameters to be free and constrained by the inflationary observables, we studied in detail its consequence on the reheating and dark matter phenomenology. We point out the connection between swampland conjecture and the scalar spectral index $n_{s}$ by PLANCK within current $2 σ$ range, and associated constraints imposed on the reheating temperature and the dark matter annihilation cross-section.
↳ hep-thhep-phPRD(2019)·24 citations
38*
Ultrahigh-energy cosmic rays: Anomalies, QCD, and LHC data
David d'Enterria🇨🇭
Measurements of proton and nuclear collisions at the Large Hadron Collider at nucleon-nucleon c.m. energies up to $s_{N N} =$ 13 TeV, have improved our understanding of hadronic interactions at the highest energies reached in collisions of cosmic rays with nuclei in the earth atmosphere, up to $s_{N N} \approx 450$ TeV. The Monte Carlo event generators (EPOS, QGSJET, and SIBYLL) commonly used to describe the air showers generated by ultrahigh-energy cosmic rays (UHECR, with $E_{C R} \approx 1 0^{17}$ -- $1 0^{20}$ eV) feature now, after parameter retuning based on LHC Run-I data, more consistent predictions on the nature of the cosmic rays at the tail of the measured spectrum. However, anomalies persist in the data that cannot be accommodated by the models. Among others, the total number of muons (as well as their maximum production depth) remains significantly underestimated (overestimated) by all models. Comparisons of EPOS, QGSJET, and SIBYLL predictions to the latest LHC data, and to collider MC generators such as PYTHIA, indicate that improved description of hard multiple minijet production and nuclear effects may help reduce part of the data--model discrepancies, shed light on the UHECR composition approaching the observed $E_{C R} \approx 1 0^{20}$ eV cutoff, and uncover any potential new physics responsible of the observed anomalies.
↳ astro-ph.HEhep-exhep-phnucl-ex+1EPJ Web Conf.(2019)·6 citations
39*
Relativistic Hydrodynamic Fluctuations
Xin An🇺🇸 · Gokce Basar🇺🇸 · Mikhail Stephanov🇺🇸 · Ho-Ung Yee🇺🇸
We present a general systematic formalism for describing dynamics of fluctuations in an arbitrary relativistic hydrodynamic flow, including their feedback (known as long-time hydrodynamic tails). The fluctuations are described by two-point equal-time correlation functions. We introduce a definition of equal time in a situation where the local rest frame is determined by the local flow velocity, and a method of taking derivatives and Wigner transforms of such equal-time correlation functions, which we call confluent. We find that the equations for confluent Wigner functions not only resemble kinetic equations, but that the kinetic equation for phonons propagating on an arbitrary background nontrivially matches the equations for Wigner functions, including relativistic inertial and Coriolis forces due to acceleration and vorticity of the flow. We also describe the procedure of renormalization of short-distance singularities which eliminates cutoff dependence, allowing efficient numerical implementation of these equations.
↳ hep-thcond-mat.stat-mechhep-phnucl-thPRC(2019)·93 citations
40*
Metastability in Quadratic Gravity
Alberto Salvio🇮🇹
Quadratic gravity is a UV completion of general relativity, which also solves the hierarchy problem. The presence of 4 derivatives implies via the Ostrogradsky theorem that the $c l a ss i c a l$ Hamiltonian is unbounded from below. Here we solve this issue by showing that the relevant solutions are not unstable but metastable. When the energies are much below a threshold (that is high enough to describe the whole cosmology) runaways are avoided. Remarkably, the chaotic inflation theory of initial conditions ensures that such bound is satisfied and we work out testable implications for the early universe. The possible instability occurring when the bound is violated not only is compatible with cosmology but would also explain why we live in a homogeneous and isotropic universe.
↳ gr-qcastro-ph.COhep-phhep-thPRD(2019)·81 citations
41*
Ruling out 3 keV warm dark matter using 21 cm-EDGES data
Atrideb Chatterjee🇮🇳 · Pratika Dayal🇳🇱 · Tirthankar Roy Choudhury🇮🇳 · Anne Hutter🇳🇱
Weakly interacting cold dark matter (CDM) particles, which are otherwise extremely successful in explaining various cosmological observations, exhibit a number of problems on small scales. One possible way of solving these problems is to invoke (so-called) warm dark matter (WDM) particles with masses $m_{x} \sim$ keV. Since the formation of structure is delayed in such WDM models, it is natural to expect that they can be constrained using observations related to the first stars, e.g., the 21 cm signal from cosmic dawn. In this work, we use a detailed galaxy formation model, Delphi, to calculate the 21 cm signal at high-redshifts and compare this to the recent EDGES observations. We find that while CDM and 5 keV WDM models can obtain a 21 cm signal within the observed redshift range, reproducing the amplitude of the observations requires the introduction of an excess radio background. On the other hand, WDM models with $m_{x} \leq 3$ keV can be ruled out since they are unable to match either the redshift range or the amplitude of the EDGES signal, irrespective of the parameters used. Comparable to values obtained from the low-redshift Lyman Alpha forest, our results extend constraints on the WDM particle to an era inaccessible by any other means; additional forthcoming 21 cm data from the era of cosmic dawn will be crucial in refining such constraints.
↳ astro-ph.COastro-ph.GAhep-phMNRAS(2019)·51 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.