Thu·Jan 30, 2020Thursday·January 30, 2020

1. 01*

   Two-Component Axionic Dark Matter Halos

   Gennady P. Berman🇺🇸 · Vyacheslav N. Gorshkov🇺🇦 · Vladimir I. Tsifrinovich🇺🇸 · Marco Merkli🇨🇦 · Vladimir V. Tereshchuk🇺🇦

   We consider a two-component dark matter halo (DMH) of a galaxy containing ultra-light axions (ULA) of different mass. The DMH is described as a Bose-Einstein condensate (BEC) in its ground state. In the mean-field (MF) limit we have derived the integro-differential equations for the spherically symmetrical wave functions of the two DMH components. We studied numerically the radial distribution of the mass density of ULA and constructed the parameters which could be used to distinguish between the two- and one-component DMH. We also discuss an interesting connection between the BEC MF ground state of a one-component DMH and Hawking temperature and entropy of a corresponding Black Hole, and Unruh temperature.

   hep-phastro-ph.GAcond-mat.othergr-qcMod.Phys.Lett.A(2020)·5 citations
2. 02*

   Low energy doubly-virtual Compton scattering from di-lepton electroproduction on a nucleon

   Vladyslav Pauk🇩🇪 · Carl E. Carlson🇺🇸 · Marc Vanderhaeghen🇩🇪

   We propose a new way to experimentally determine the subleading low-energy structure constant of doubly-virtual Compton scattering on a proton. Such empirical determination will reduce the theoretical model error in estimates of the hadronic correction to the muonic hydrogen Lamb shift. We demonstrate that the di-lepton forward-backward asymmetry in the $e^{-}p\to e^{-}p{e}^{-}{e}^{+}$ process, which can be accessed at electron scattering facilities, yields a large sensitivity to this so far unknown low-energy constant.

   hep-phnucl-thPRC(2020)·8 citations
3. 03*

   Detecting Light Boson Dark Matter through Conversion into Magnon

   So Chigusa🇯🇵 · Takeo Moroi🇯🇵 · Kazunori Nakayama🇯🇵

   Light boson dark matter such as axion or hidden photon can be resonantly converted into a magnon in a magnetic insulator under the magnetic field, which can be detected experimentally. We provide a quantum mechanical formulation for the magnon event rate and show that the result is consistent with that obtained by a classical calculation. Besides, it is pointed out that the experimental setup of the QUAX proposal for the axion detection also works as a detector of hidden photon dark matter. It has good sensitivity in the mass range around 1 meV, which is beyond astrophysical constraints.

   hep-phPRD(2020)·64 citations
4. 04*

   Review of proton and nuclear shape fluctuations at high energy

   Heikki Mäntysaari🇫🇮

   Determining the inner structure of protons and nuclei in terms of their fundamental constituents has been one of the main tasks of high energy nuclear and particle physics experiments. This quest started as a mapping of the (average) parton densities as a function of longitudinal momentum fraction and resolution scale. Recently, the field has progressed to more differential imaging, where one important development is the description of the event-by-event quantum fluctuations in the wave function of the colliding hadron. In this Review, recent developments on the extraction of proton and nuclear transverse geometry with event-by-event fluctuations from collider experiments at high energy is presented. The importance of this fundamentally interesting physics in other collider experiments like in studies of the properties of the Quark Gluon Plasma is also illustrated.

   hep-phhep-exnucl-exnucl-thRept.Prog.Phys.(2020)·103 citations
5. 05*

   Confronting Experimental Data with Heavy-Ion Models: Rivet for Heavy Ions

   Christian Bierlich🇸🇪 · Andy Buckley🇬🇧 · Christian Holm Christensen🇩🇰 · Peter Harald Lindenov Christiansen🇸🇪 · Cody B. Duncan🇦🇺 · Jan Fiete Grosse-Oetringhaus🇨🇭 · Przemyslaw Karczmarczyk🇵🇱 · Patrick Kirchgaeßer🇩🇪 · Jochen Klein🇮🇹 · Leif Lönnblad🇸🇪 · Roberto Preghenella🇮🇹 · Christine O. Rasmussen🇸🇪 · Maria Stefaniak🇵🇱 · Vytautas Vislavicus🇩🇰

   The Rivet library is an important toolkit in particle physics, and serves as a repository for analysis data and code. It allows for comparisons between data and theoretical calculations of the final state of collision events. This paper outlines several recent additions and improvements to the framework to include support for analysis of heavy ion collision simulated data. The paper also presents examples of these recent developments and their applicability in implementing concrete physics analyses.

   hep-phhep-exnucl-exnucl-thEPJC(2020)·25 citations
6. 06*

   Scale and Scheme Variations in Unitarized NLO Merging

   Leif Gellersen🇸🇪 · Stefan Prestel🇸🇪

   Precision background predictions with well-defined uncertainty estimates are important for interpreting collider-physics measurements and for planning future high-energy collider experiments. It is especially important to estimate the perturbative uncertainties in predictions of inclusive measurements of jet observables, that are designed to be largely insensitive to non-perturbative effects such as the structure of beam-remnants, multi-parton scattering or hadronization. In this study, we discuss possible pit-falls in defining the perturbative uncertainty of unitarized next-to-leading order multi-jet merged predictions, using the PYTHIA event generator as our vehicle. For this purpose, we consider different choices of unitarized NLO merging schemes as well as consistent variations of renormalization scales in different parts of the calculation. Such a combined discussion allows to rank the contribution of scale variations to the error budget in comparison to other contributions due to algorithmic choices that are often assumed fixed. The scale uncertainty bands of different merging schemes largely overlap, but differences between the "central" predictions in different schemes can remain comparable to scale uncertainties even for very well-separated jets, or be larger than scale uncertainties in transition regions between calculations of different jet multiplicity. The availability of these variations within PYTHIA will enable more systematic studies of perturbative uncertainties in precision background calculations in the future.

   hep-phPRD(2020)·6 citations
7. 07*

   The Higgs-portal for vector Dark Matter and the Effective Field Theory approach: a reappraisal

   Giorgio Arcadi🇮🇹 · Abdelhak Djouadi🇫🇷 · Marumi Kado🇮🇹

   We reanalyze the effective field theory approach for the scenario in which the particles that account for the dark matter (DM) in the universe are vector states that interact only or mainly through the Standard Model-like Higgs boson observed at the LHC. This model-independent and simple approach, with a minimal set of new input parameters, is widely used as a benchmark in DM searches and studies in astroparticle and collider physics. We show that this effective theory could be the limiting case of ultraviolet complete models, taking as an example the one based on a spontaneously broken U(1) gauge symmetry that incorporates a dark gauge boson and an additional scalar that mixes with the standard Higgs boson. Hence, despite the presence of the new degrees of freedom, measurements of the invisible decay branching ratio of the Higgs boson, as performed at colliders such as the CERN LHC, can be interpreted consistently in such an effective framework and can be made complementary to results of DM searches in direct detection experiments.

   hep-phPLB(2020)·48 citations
8. 08*

   Simulation of an experiment on looking for sterile neutrinos at nuclear reactor

   S. V. Silaeva🇷🇺 · V. V. Sinev🇷🇺

   The simulation of an experiment on looking for sterile neutrinos at a nuclear reactor at short distances is presented. It has been shown that statistical fluctuations in experimental bins always imitate the oscillatory behavior of the spectrum. An amplitude of the detectable oscillations decreases when statistics grows up in case of oscillations absence, while mass parameter tends to be accidental. When we simulate spectra in a detector with oscillations the parameters found in fitting become close to parameters applied to spectra starting from statistics 10${}^5$ events in near detector.

   hep-phhep-ex3 citations
9. 09*

   Polarized NLO EW $e^{+}{e}^{-}$ cross section calculations with ReneSANCe-v1.0.0

   Renat Sadykov🇷🇺 · Vitaly Yermolchyk🇷🇺

   In this paper we present a new Monte Carlo event generator ReneSANCe for simulation of processes at electron-positron colliders. In the current release of the generator the Bhabha scattering ($e^{+}{e}^{-}\to e^{-}{e}^{+}$) and Higgs-strahlung ($e^{+}{e}^{-}\to ZH$) process are implemented. Based on the SANC (Support for Analytic and Numeric Calculations for experiments at colliders) modules, the new generator takes into account complete one-loop and some higher-order electroweak radiative corrections with finite particle masses and polarizations. The new generator effectively operates in the collinear region and at the $ZH$ production threshold. It is constructed in such a way that new processes can be easily added. The paper contains a theoretical description of the SANC approach, numerical validations and manual.

   hep-phComput.Phys.Commun.(2020)·31 citations
10. 10*

    Natural Philosophy versus Philosophy of Naturalness

    Goran Senjanovic🇮🇹

    I reflect on some of the basic aspects of present day Beyond the Standard Model particle physics, focusing mostly on the issues of naturalness, in particular on the so-called hierarchy problem. To all of us, physics as natural science emerged with Galileo and Newton, and led to centuries of unparalleled success in explaining and often predicting new phenomena of nature. I argue here that the long standing obsession with the hierarchy problem as a guiding principle for the future of our field has had the tragic consequence of deviating high energy physics from its origins as natural philosophy, and turning it into a philosophy of naturalness.

    hep-phhep-exhep-thphysics.hist-phMod.Phys.Lett.A(2020)·11 citations
11. 11*

    Muon g-2 vs LHC Run 2 in Supersymmetric Models

    Motoi Endo🇯🇵 · Koichi Hamaguchi🇯🇵 · Sho Iwamoto🇮🇹 · Teppei Kitahara🇮🇱

    Supersymmetric models with sub-TeV charginos and sleptons have been a candidate for the origin of the long-standing discrepancy in the muon anomalous magnetic moment (g-2). By gathering all the available LHC Run 2 results, we investigate the latest LHC constraints on models that explain the anomaly by their chargino contribution to the muon g-2. It is shown that the parameter regions where sleptons are lighter than charginos are strongly disfavored. In contrast, we find that the models with $m_{{\tilde{\mu }}_{\mathrm{L}}}\gtrsim m_{{\tilde{\chi }}_1^{\pm }}$ are still widely allowed, where the lighter chargino dominantly decays into a W-boson and a neutralino.

    hep-phhep-exJHEP(2020)·45 citations
12. 12*

    Precise determination of ${\alpha }_s$ from relativistic quarkonium sum rules

    Diogo Boito🇧🇷 · Vicent Mateu🇪🇸

    We determine the strong coupling ${\alpha }_s(m_Z)$ from dimensionless ratios of roots of moments of the charm- and bottom-quark vector and charm pseudo-scalar correlators, dubbed $R_q^{X,n}\equiv (M_q^{X,n}{)}^{\frac{1}{n}}/(M_q^{X,n+1}{)}^{\frac{1}{n+1}}$, with $X=V,P$, as well as from the $0$-th moment of the charm pseudo-scalar correlator, $M_c^{P,0}$. In the quantities we use, the mass dependence is very weak, entering only logarithmically, starting at $\mathcal{O}({\alpha }_s^2)$. We carefully study all sources of uncertainties, paying special attention to truncation errors, and making sure that order-by-order convergence is maintained by our choice of renormalization scale variation. In the computation of the experimental uncertainty for the moment ratios, the correlations among individual moments are properly taken into account. Additionally, in the perturbative contributions to experimental vector-current moments, ${\alpha }_s(m_Z)$ is kept as a free parameter such that our extraction of the strong coupling is unbiased and based only on experimental data. The most precise extraction of ${\alpha }_s$ from vector correlators comes from the ratio of the charm-quark moments $R_c^{V,2}$ and reads ${\alpha }_s(m_Z)=0.1168\pm 0.0019$, as we have recently discussed in a companion letter. From bottom moments, using the ratio $R_b^{V,2}$, we find ${\alpha }_s(m_Z)=0.1186\pm 0.0048$. Our results from the lattice pseudo-scalar charm correlator agree with the central values of previous determinations, but have larger uncertainties due to our more conservative study of the perturbative error. Averaging the results obtained from various lattice inputs for the $n=0$ moment we find ${\alpha }_s(m_Z)=0.1177\pm 0.0020$. Combining experimental and lattice information on charm correlators into a single fit we obtain ${\alpha }_s(m_Z)=0.1170\pm 0.0014$, which is the main result of this article.

    hep-phhep-latJHEP(2020)·23 citations
13. 13*

    Rare kaon decays and CP violation

    Antonio Pich🇪🇸

    Owing to the strong suppression of flavour-changing neutral-current transitions in the Standard Model, rare kaon decays constitute a superb tool to constrain hypothetical new-physics interactions. At the same time, they provide many interesting tests of the Standard Model itself, being sensitive both to short-distance electroweak scales and to the long-distance QCD dynamics. A brief overview of the current status is presented. The Standard Model prediction for the direct CP-violating ratio ${\epsilon }^{\prime }/\epsilon$ is also discussed.

    hep-phPoS(2020)·2 citations
14. 14*

    Cross-conductivity: novel transport coefficients to constrain the hadronic degrees of freedom of nuclear matter

    Jean-Bernard Rose🇩🇪 · Moritz Greif🇩🇪 · Jan Hammelmann🇩🇪 · Jan A. Fotakis🇩🇪 · Gabriel S. Denicol🇧🇷 · Hannah Elfner🇩🇪 · Carsten Greiner🇩🇪

    In general, the constituents of the bulk matter produced in heavy-ion collisions carry, besides electric charge, multiple other conserved quantum numbers like baryon number and strangeness. Therefore, an electric field will not only generate an electric current but, at the same time, also currents in baryon number and strangeness. We propose that the impact of the electric field on these conserved currents should be characterized by additional transport coefficients, which we call cross-conductivities. In this paper, we introduce and present a calculation of these cross-conductivities from the Green-Kubo formalism within the transport code SMASH for different chemical compositions of hadron resonance gases. We find that the coefficients underlie an ordering in the active degrees of freedom and that thus the chemical composition of the system plays a crucial role. Further, we argue that in future comparisons of lattice QCD calculations with these findings, one could constrain which degrees of freedom and their corresponding charge properties are relevant for the QCD dynamics of the system.

    ↳ nucl-thhep-phPRD(2020)·29 citations
15. 15*

    Number of constituent quark scaling of elliptic flows in high multiplicity p-Pb collisions at $\sqrt{s_{NN}}=$ 5.02 TeV

    Wenbin Zhao🇨🇳 · Che Ming Ko🇺🇸 · Yu-Xin Liu🇨🇳 · Guang-You Qin🇨🇳 · Huichao Song🇨🇳

    We briefly summarize our recent study on the number of constituent quark (NCQ) scaling of hadron elliptic flows in high multiplicity p-Pb collisions at $\sqrt{s_{NN}}=$ 5.02 TeV. With the inclusion of hadron production via the quark coalescence model at intermediate $p_T$, the viscous hydrodynamics at low $p_T$, and jet fragmentation at high $p_T$, our $Hydro-Coal-Frag$ model provides a nice description of the $p_T$-spectra and differential elliptic flow $v_2(p_T)$ of pions, kaons and protons over the $p_T$ range from 0 to 6 GeV. Our results demonstrate that including the quark coalescence is essential for reproducing the observed approximate NCQ scaling of hadron $v_2$ at intermediate $p_T$ in experiments, indicating strongly the existence of partonic degrees of freedom and the formation of quark-gluon plasma in high multiplicity p--Pb collisions at the LHC.

    ↳ nucl-thhep-phnucl-exNPA(2021)·2 citations
16. 16*

    Neutron stars with a generalized Proca hair and spontaneous vectorization

    Ryotaro Kase🇯🇵 · Masato Minamitsuji🇵🇹 · Shinji Tsujikawa🇯🇵

    In a class of generalized Proca theories, we study the existence of neutron star solutions with a nonvanishing temporal component of the vector field $A_{\mu }$ approaching 0 toward spatial infinity, as they may be the endpoints of tachyonic instabilities of neutron star solutions in general relativity with $A_{\mu }=0$. Such a phenomenon is called spontaneous vectorization, which is analogous to spontaneous scalarization in scalar-tensor theories with nonminimal couplings to the curvature or matter. For the nonminimal coupling $\beta XR$, where $\beta$ is a coupling constant and $X=-A_{\mu }{A}^{\mu }/2$, we show that there exist both 0-node and 1-node vector-field solutions, irrespective of the choice of the equations of state of nuclear matter. The 0-node solution, which is present only for $\beta =-\mathcal{O}(0.1)$, may be induced by some nonlinear effects such as the selected choice of initial conditions. The 1-node solution exists for $\beta =-\mathcal{O}(1)$, which suddenly emerges above a critical central density of star and approaches the general relativistic branch with the increasing central density. We compute the mass $M$ and radius $r_s$ of neutron stars for some realistic equations of state and show that the $M$-$r_s$ relations of 0-node and 1-node solutions exhibit notable difference from those of scalarized solutions in scalar-tensor theories. Finally, we discuss the possible endpoints of tachyonic instabilities.

    ↳ gr-qcastro-ph.HEhep-phhep-thPRD(2020)·55 citations
17. 17*

    From correlation functions to event shapes in QCD

    D. Chicherin🇩🇪 · J.M. Henn🇩🇪 · E. Sokatchev🇫🇷 · K. Yan🇩🇪

    We present a method for calculating event shapes in QCD based on correlation functions of conserved currents. The method has been previously applied to the maximally supersymmetric Yang-Mills theory, but we demonstrate that supersymmetry is not essential. As a proof of concept, we consider the simplest example of a charge-charge correlation at one loop (leading order). We compute the correlation function of four electromagnetic currents and explain in detail the steps needed to extract the event shape from it. The result is compared to the standard amplitude calculation. The explicit four-point correlation function may also be of interest for the CFT community.

    ↳ hep-thhep-phJHEP(2021)·37 citations
18. 18*

    Evolution of quasiperiodic structures in non-ideal hydrodynamic description of phase transitions

    D. N. Voskresensky🇷🇺

    Various phase transitions could have taken place in the early Universe, and may occur in the course of heavy-ion collisions and supernova explosions, in proto-neutron stars, cold compact stars, and in the condensed matter at terrestrial conditions. Most generally, the dynamics of the density and temperature at first- and second-order phase transitions can be described with the help of the equations of non-ideal hydrodynamics. In the given work some novel solutions are found describing the evolution of quasiperiodic structures that are formed in the course of the phase transitions. Although this consideration is very general, particular examples of quark-hadron and nuclear liquid-gas first-order phase transitions to the uniform k_0=0 state and pion condensate second-order phase transition to non-uniform k_0\neq 0 state in dense baryon matter are considered.

    ↳ nucl-thhep-phUniverse(2020)·3 citations
19. 19*

    Axion Constraints from Quiescent Soft Gamma-ray Emission from Magnetars

    Sheridan J. Lloyd (1)🇬🇧 · Paula M. Chadwick (1)🇬🇧 · Anthony M. Brown (1)🇬🇧 · Huai-ke Guo (2)🇺🇸 · Kuver Sinha (2) ((1) Centre for Advanced Instrumentation, Dept. of Physics, University of Durham, Durham, UK, (2) Department of Physics and Astronomy, University of Oklahoma, Norman, USA)🇺🇸

    Axion-like-particles (ALPs) emitted from the core of a magnetar can convert to photons in its magnetosphere. The resulting photon flux is sensitive to the product of $(i)$ the ALP-nucleon coupling $G_{an}$ which controls the production cross section in the core and $(ii)$ the ALP-photon coupling $g_{a\gamma \gamma }$ which controls the conversion in the magnetosphere. We study such emissions in the soft-gamma-ray range (300 keV to 1 MeV), where the ALP spectrum peaks and astrophysical backgrounds from resonant Compton upscattering are expected to be suppressed. Using published quiescent soft-gamma-ray flux upper limits in 5 magnetars obtained with $CGRO$ COMPTEL and $INTEGRAL$ SPI/IBIS/ISGRI, we put limits on the product of the ALP-nucleon and ALP-photon couplings. We also provide a detailed study of the dependence of our results on the magnetar core temperature. We further show projections of our result for future $Fermi$-GBM observations. Our results motivate a program of studying quiescent soft-gamma-ray emission from magnetars with the $Fermi$-GBM.

    ↳ astro-ph.HEhep-phPRD(2021)·16 citations
20. 20*

    All-inclusive interacting dark sector cosmologies

    Weiqiang Yang🇨🇳 · Eleonora Di Valentino🇬🇧 · Olga Mena🇪🇸 · Supriya Pan🇮🇳 · Rafael C. Nunes🇧🇷

    In this paper we explore possible extensions of Interacting Dark Energy cosmologies, where Dark Energy and Dark Matter interact non-gravitationally with one another. In particular, we focus on the neutrino sector, analyzing the effect of both neutrino masses and the effective number of neutrino species. We consider the Planck 2018 legacy release data combined with several other cosmological probes, finding no evidence for new physics in the dark radiation sector. The current neutrino constraints from cosmology should be therefore regarded as robust, as they are not strongly dependent on the dark sector physics, once all the available observations are combined. Namely, we find a total neutrino mass $M_{\nu }<0.15$ eV and a number of effective relativistic degrees of freedom of $N_{\mathrm{eff}}=3.03_{-0.33}^{+0.33}$, both at 95\% CL, which are close to those obtained within the $\Lambda$CDM cosmology, $M_{\nu }<0.12$ eV and $N_{\mathrm{eff}}=3.00_{-0.35}^{+0.36}$ for the same data combination.

    ↳ astro-ph.COgr-qchep-phPRD(2020)·95 citations
21. 21*

    Charmonium contribution to $B \rightarrow K\ell^+\ell^-: testing the factorization approximation on the lattice

    Katsumasa Nakayama🇩🇪 · Tsutomu Ishikawa🇯🇵 · Shoji Hashimoto🇯🇵

    We report the current status of a study of charmonium contribution to $B\to K{\ell }^{+}{\ell }^{-}$ on the lattice. Our lattice calculation tests the factorization approximation for this contribution. In order to control the problem of the artificial divergence, we focus on the low $q^2$ region with a small b-quark mass. We also take into account the renormalization constants of relevant four-quark operators calculated through the temporal moments. Results suggest a violation of the factorization approximation.

    ↳ hep-lathep-phPoS(2020)·6 citations
22. 22*

    Investigating non-Gaussianity in Cosmic Microwave Background Temperature Maps using Spherical Harmonic Phases

    Sarvesh Kumar Yadav · Rajib Saha🇮🇳

    In this article, we extend previous studies based on CMB spherical harmonic phases (SHP) to examine the validity of the hypothesis that the temperature field of the CMB is consistent with a Gaussian random field (GRF). The null hypothesis is that the corresponding CMB SHP are independent and identically distributed in terms of a uniform distribution in the interval [0, 2$\pi$] \citep{1986ApJ...304...15B,2013rossmanith}. We devise a new model-independent method where we use ordered and non-parametric Rao's statistic, based on sample arc-lengths to comprehensively test uniformity and independence of SHP. We performed our analysis on the scales limited by spherical harmonic modes $\le$ 128, to restrict ourselves to signal-dominated regions. To find the non-uniform or dependent sets of SHP, we calculate the statistic for the data and 10000 Monte Carlo simulated uniformly random sets of SHP and use 0.05 and 0.001 $\alpha$ levels to distinguish between statistically significant and highly significant detections. We first establish the performance of our method using simulated Gaussian, non-Gaussian CMB temperature maps, along with observed non-Gaussian 100 and 143 GHz Planck channel maps. We find that our method performs efficiently and accurately in detecting phase correlations generated in all of the non-Gaussian simulations and observed foreground contaminated 100 and 143 GHz Planck channel temperature maps. We apply our method on the Planck satellite mission's final released CMB temperature anisotropy maps- COMMANDER, SMICA, NILC, and SEVEM along with WMAP 9 year released ILC map. We report that SHP corresponding to some of the $m$-modes is non-uniform, some of the $\ell$ mode SHP and neighboring mode pair SHP are correlated in cleaned CMB maps. The detection of non-uniformity or correlation in the SHP indicates the presence of non-Gaussian signals in the foreground minimized CMB maps.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2022)·3 citations
23. 23*

    Implications of Milky Way Substructures for the Nature of Dark Matter

    María Benito🇪🇪 · Juan Carlos Criado🇪🇪 · Gert Hütsi🇪🇪 · Martti Raidal🇪🇪 · Hardi Veermäe🇪🇪

    We study how the indirect observation of dark matter substructures in the Milky Way, using recent stellar stream studies, translates into constraints for different dark matter models. Particularly, we use the measured number of dark subhalos in the mass range $10^7-10^9{\mathrm{M}}_{\odot }$ to constrain modifications of the subhalo mass function compared to the cold dark matter scenario. We obtain the lower bounds $m_{\mathrm{WDM}}>3.2\mathrm{keV}$ and $m_{\mathrm{FDM}}>5.2\times 10^{-21}\mathrm{eV}$ on the warm dark matter and fuzzy dark matter particle mass, respectively. When dark matter is coupled to a dark radiation bath, we find that kinetic decoupling must take place at temperatures higher than $T_{\mathrm{kd}}>0.7\mathrm{keV}$. We also discuss future prospects of stellar stream observations.

    ↳ astro-ph.COastro-ph.GAhep-phPRD(2020)·43 citations
24. 24*

    A dS obstruction and its phenomenological consequences

    Miguel Montero🇺🇸 · Thomas Van Riet🇧🇪 · Victoria Venken🇧🇪

    In this note we observe that positive runaway potentials can generically be stabilized by abelian $p$-form fluxes, leading to parametrically controlled de Sitter solutions after compactification to a lower dimension. When compactifying from 4d to 2d the dS solutions are metastable, whereas all higher dimensional cases are unstable. The existence of these dS solutions require that a certain inequality involving the derivatives of the potential and $p$-form gauge coupling is satisfied. This inequality is not satisfied in simple stringy examples (outside of the scope of Maldacena-Nuñez), which unsurprisingly avoid this route to dS solutions. We can apply our techniques to construct $d{S}_2$ solutions in the Standard Model plus an additional runaway scalar such as quintessence. Demanding that these are avoided leads to (weak) phenomenological constraints on the time variation of the fine structure constant and QCD axion-photon coupling.

    ↳ hep-thhep-phJHEP(2020)·20 citations
25. 25*

    Production of ${}^4\mathrm{Li}$ and $p-{}^3\mathrm{He}$ correlation function in relativistic heavy-ion collisions

    Sylwia Bazak🇵🇱 · Stanislaw Mrowczynski🇵🇱

    The thermal and coalescence models both describe well yields of light nuclei produced in relativistic heavy-ion collisions at LHC. We propose to measure the yield of ${}^4\mathrm{Li}$ and compare it to that of ${}^4\mathrm{He}$ to falsify one of the models. Since the masses of ${}^4\mathrm{He}$ and ${}^4\mathrm{Li}$ are almost equal, the yield of ${}^4\mathrm{Li}$ is about 5 times bigger than that of ${}^4\mathrm{He}$ in the thermal model because of different numbers of spin states of the two nuclides. Their internal structures are, however, very different: the alpha particle is well bound and compact while ${}^4\mathrm{Li}$ is weakly bound and loose. Consequently, the ratio of yields of ${}^4\mathrm{Li}$ to ${}^4\mathrm{He}$ is significantly smaller in the coalescence model and it strongly depends on the collision centrality. Since the nuclide ${}^4\mathrm{Li}$ is unstable and it decays into ${}^3\mathrm{He}$ and $p$, the yield of ${}^4\mathrm{Li}$ can be experimentally obtained through a measurement of the $p-{}^3\mathrm{He}$ correlation function. The function carries information not only about the yield of ${}^4\mathrm{Li}$ but also about the source of ${}^3\mathrm{He}$ and allows one to determine through a source-size measurement whether of ${}^3\mathrm{He}$ is directly emitted from the fireball or it is formed afterwards. We compute the correlation function taking into account the $s-$wave scattering and Coulomb repulsion together with the resonance interaction responsible for the ${}^4\mathrm{Li}$ nuclide. We discuss how to infer information about an origin of ${}^3\mathrm{He}$ from the correlation function, and finally a method to obtain the yield of ${}^4\mathrm{Li}$ is proposed.

    ↳ nucl-thhep-phnucl-exEPJA(2020)·27 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.