Wed·Sep 25, 2019Wednesday·September 25, 2019

1. 01*

   The HTL Lagrangian at NLO: the photon case

   Stefano Carignano🇪🇸 · Margaret E. Carrington🇨🇦 · Joan Soto🇪🇸

   We calculate the two loop hard correction to the photon self-energy in an electron-positron plasma (EPP) for arbitrary soft momenta. This provides the only missing ingredient to obtain the Hard Thermal Loop (HTL) effective Lagrangian at next-to-leading order (NLO), and the full photon propagator at the same order. This result can be easily extended to obtain the soft photon propagator in a quark gluon plasma. We use the Keldysh representation of the real time formalism in the massless fermion limit, and dimensional regularization (DR) to regulate any ultraviolet (UV), infrared (IR) or collinear divergences that appear in the intermediate steps of the calculation. In the limit of soft photon momenta, our result is finite. It not only provides an $\mathcal{O}(\alpha )$ correction to the Debye mass, but also a new non-local structure. A consistent regularization of radial and angular integrals is crucial to get this new structure. As an application we calculate the plasmon dispersion relations at NLO.

   hep-phPLB(2020)·22 citations
2. 02*

   Towards hardware acceleration for parton densities estimation

   Stefano Carrazza🇮🇹 · Juan Cruz-Martinez🇮🇹 · Jesús Urtasun-Elizari🇮🇹 · Emilio Villa🇮🇹

   In this proceedings we describe the computational challenges associated to the determination of parton distribution functions (PDFs). We compare the performance of the convolution of the parton distributions with matrix elements using different hardware instructions. We quantify and identify the most promising data-model configurations to increase PDF fitting performance in adapting the current code frameworks to hardware accelerators such as graphics processing units.

   hep-phcs.LGhep-exFrascati Phys.Ser.(2019)·4 citations
3. 03*

   The electroweak effective field theory from on-shell amplitudes

   Gauthier Durieux🇮🇱 · Teppei Kitahara🇮🇱 · Yael Shadmi🇮🇱 · Yaniv Weiss🇮🇱

   We apply on-shell methods to the bottom-up construction of electroweak amplitudes, allowing for both renormalizable and non-renormalizable interactions. We use the little-group covariant massive-spinor formalism, and flesh out some of its details along the way. Thanks to the compact form of the resulting amplitudes, many of their properties, and in particular the constraints of perturbative unitarity, are easily seen in this formalism. Our approach is purely bottom-up, assuming just the standard-model electroweak spectrum as well as the conservation of electric charge and fermion number. The most general massive three-point amplitudes consistent with these symmetries are derived and studied in detail, as the primary building blocks for the construction of scattering amplitudes. We employ a simple argument, based on tree-level unitarity of four-point amplitudes, to identify the three-point amplitudes that are non-renormalizable at tree level. This bottom-up analysis remarkably reproduces many low-energy relations implied by electroweak symmetry through the standard-model Higgs mechanism and beyond it. We then discuss four-point amplitudes. The gluing of three-point amplitudes into four-point amplitudes in the massive spinor helicity formalism is clarified. As an example, we work out the ${\psi }^c\psi Zh$ amplitude, including also the non-factorizable part. The latter is an all-order expression in the effective-field-theory expansion. Further constraints on the couplings are obtained by requiring perturbative unitarity. In the ${\psi }^c\psi Zh$ example, one for instance obtains the renormalizable-level relations between vector and fermion masses and gauge and Yukawa couplings. We supplement our bottom-up derivations with a matching of three- and four-point amplitude coefficients onto the standard-model effective field theory (SMEFT) in the broken electroweak phase.

   hep-phhep-thJHEP(2020)·125 citations
4. 04*

   Pion and kaon condensation at zero temperature in three-flavor $\chi$PT at nonzero isospin and strange chemical potentials at next-to-leading order

   Prabal Adhikari🇺🇸 · Jens O. Andersen🇳🇴

   We consider three-flavor chiral perturbation theory ($\chi$PT) at zero temperature and nonzero isospin (${\mu }_I$) and strange (${\mu }_S$) chemical potentials. The effective potential is calculated to next-to-leading order (NLO) in the ${\pi }^{\pm }$-condensed phase, the $K^{\pm }$-condensed phase, and the $K^0/{\bar{K}}^0$-condensed phase. It is shown that the transitions from the vacuum phase to these phases are second order and take place when, $|{\mu }_I|=m_{\pi }$, $|\frac{1}{2}{\mu }_I+{\mu }_S|=m_K$, and $|-\frac{1}{2}{\mu }_I+{\mu }_S|=m_K$, respectively at tree level and remains unchanged at NLO. The transition between the two condensed phases is first order. The effective potential in the pion-condensed phase is independent of ${\mu }_S$ and in the kaon-condensed phases, it only depends on the combinations $\pm \frac{1}{2}{\mu }_I+{\mu }_S$ and not separately on ${\mu }_I$ and ${\mu }_S$. We calculate the pressure, isospin density and the equation of state in the pion-condensed phase and compare our results with recent $(2+1)$-flavor lattice QCD data. We find that the three-flavor $\chi$PT results are in good agreement with lattice QCD for ${\mu }_I<200$ MeV, however for larger values $\chi$PT produces values for observables that are consistently above lattice results. For ${\mu }_I>200$ MeV, the two-flavor results are in better agreement with lattice data. Finally, we consider the observables in the limit of very heavy $s$-quarks, where they reduce to their two-flavor counterparts with renormalized couplings. The disagreement between the predictions of two and three flavor $\chi$PT can largely be explained by the differences in the experimental values of the low-energy constants.

   hep-phnucl-thJHEP(2020)·25 citations
5. 05*

   Novel matter effects on neutrino oscillations observables

   Adam Zettel🇺🇸 · Mihai Horoi🇺🇸

   In a recent article (arxiv:1803.06332) we noticed that the electron density in condensed matter exhibits large spikes close to the atomic nuclei. We showed that these spikes in the electron densities, 3-4 orders of magnitude larger than those inside the Sun's core, have no effect on the neutrino emission and absorption probabilities or on the neutrinoless double beta decay probability. However, it was not clear if the effect of these spikes is equivalent to that of an average constant electron density in matter. We investigated these effects by a direct integration of the coupled Dirac equations describing the propagation of flavor neutrinos into, through, and out of the matter. We found little evidence that these spikes affect the standard oscillations probabilities, but found a new fast and efficient algorithm of calculating these probabilities for neutrinos propagating through varying electron densities.

   hep-ph0 citations
6. 06*

   CutLang: a cut-based HEP analysis description language and runtime interpreter

   Gokhan Unel🇺🇸 · Sezen Sekmen🇰🇷 · Anna Monica Toon🇺🇸

   We present CutLang, an analysis description language and runtime interpreter for high energy collider physics data analyses. An analysis description language is a declerative domain specific language that can express all elements of a data analysis in an easy and unambiguous way. A full-fledged human readable analysis description language, incorporating logical and mathematical expressions, would eliminate many programming difficulties and errors, consequently allowing the scientist to focus on the goal, but not on the tool. In this paper, we discuss the guiding principles and scope of the CutLang language, implementation of the CutLang runtime interpreter and the CutLang framework, and demonstrate an example of top pair reconstruction.

   hep-phphysics.comp-phJ.Phys.Conf.Ser.(2020)·10 citations
7. 07*

   Standard Model of Particle Physics Violating Crypto-Nonlocal Realism

   Yu Shi🇨🇳 · Ji-Chong Yang🇨🇳

   It has been well established that quantum mechanics (QM) violates Bell inequalities (BI), which are consequences of local realism (LR). Remarkably QM also violates Leggett inequalities (LI), which are consequences of a class of nonlocal realism called crypto-nonlocal realism (CNR). Both LR and CNR assume that measurement outcomes are determined by preexisting objective properties, as well as hidden variables (HV) not considered in QM. We extend CNR and LI to include the case that the measurement settings are not externally fixed, but determined by hidden variables (HV). We derive a new version of LI, which is then shown to be violated by entangled $B_d$ mesons, if charge-conjugation-parity (CP) symmetry is indirectly violated, as indeed established. The experimental result is quantitatively estimated by using the indirect CP violation parameter, and the maximum of a suitably defined relative violation is about $2.7\%$. Our work implies that standard model (SM) of particle physics violates CNR. Our LI can also be tested in other systems such as photon polarizations.

   hep-phquant-phEPJC(2020)·10 citations
8. 08*

   Breaking of Lorentz Invariance in Electron-Proton Parity Violation

   Alexander Michel🇺🇸 · Marc Sher🇺🇸

   A popular framework for exploring Lorentz violation is the Standard Model Extension. This extension contains a large number of parameters that can be bounded in various experiments. Most studies, however, focus on the fermion or photon sector. Here, we consider Lorentz violation in the weak vector boson sector. The strongest bounds come from measurements of the asymmetry in Moller scattering. We study the bounds that can be obtained from future measurements of the parity violating asymmetry in deep inelastic electron-proton scattering at the EIC, the LHeC and the FCC-eh. For the FCC-eh, the bounds could be substantially improved over current bounds by including timing information.

   hep-phhep-exPRD(2019)·6 citations
9. 09*

   Single-spin asymmetries at two loops

   Sanjin Benic🇯🇵 · Yoshitaka Hatta🇺🇸 · Hsiang-nan Li🇹🇼 · Dong-Jing Yang🇹🇼

   We find a novel mechanism for generating transverse single-spin asymmetry (SSA) in semi-inclusive deep inelastic scattering, distinct from the known ones which involve the Sivers and Collins functions, or their collinear twist-three counterparts. It is demonstrated that a phase needed for SSA can be produced purely within a parton-level cross section starting at two loops. We identify the complete set of two-loop diagrams for SSA, and discuss their gauge invariance and collinear factorization which features the $g_T$ distribution function. In the $k_T$ factorization framework, many more sources for SSA exist, and contributions from all possible two-parton transverse-momentum-dependent parton distribution functions are presented up to two loops and twist three.

   hep-phPRD(2019)·27 citations
10. 10*

    Precision Model-Independent Bounds from Global Analysis of $b\to c\ell \nu$ Form Factors

    Thomas D. Cohen🇺🇸 · Henry Lamm🇺🇸 · Richard F. Lebed🇺🇸

    We present a model-independent global analysis of hadronic form factors for the semileptonic decays $b\to c\ell \nu$ that exploits lattice-QCD data, dispersion relations, and heavy-quark symmetries. The analysis yields predictions for the relevant form factors, within quantifiable bounds. These form factors are used to compute the semileptonic ratios $R(H_c)$ and various decay-product polarizations. In particular, we find $R(D_s^{\ast })=0.20(3)$ and $R(J/\psi )=0.25(3)$, predictions that can be compared to results of upcoming LHCb measurements. In developing this treatment, we obtain leading-order NRQCD results for the nonzero-recoil relations between the $B_c^{+}\to \{J/\psi ,{\eta }_c\}$ form factors.

    hep-phhep-exhep-latnucl-thPRD(2019)·30 citations
11. 11*

    DAMPE Excess from Leptophilic Vector Dark Matter: Model Independent Approach

    Seyed Yaser Ayazi🇮🇷 · Ahmad Mohamadnejad🇮🇷

    We study all extensions of the Standard Model (SM) with a vector dark matter (VDM) candidate which can explain the peak structure observed by recent DAMPE experiment in electron-positron cosmic ray spectrum. In this regard, we consider all leptophilic renormalizable VDM-SM interactions through scalar, spinor, and vector mediators. We show that only two out of six possible models could produce DAMPE signal by annihilation of VDM with the mass about 1.5 TeV in a nearby subhalo whilst simultaneously satisfying constraints from DM relic density, direct/indirect detection, and the collider bounds. These two models are the ones with scalar/pseudoscalar mediator $\varphi$ with $M_{\varphi }\in [1500,3000]$ GeV.

    hep-phJ.Phys.G(2020)·9 citations
12. 12*

    $J/\psi$ decay into $\varphi (\omega )$ and vector-vector molecular states

    R. Molina🇧🇷 · L. R. Dai🇨🇳 · L. S. Geng🇨🇳 · E. Oset🇪🇸

    Based on the picture that the $f_0(1370),f_0(1710),f_2(1270),f_2^{\prime }(1525),{\bar{K}}_2^{\ast 0}(1430)$ resonances are dynamically generated from the vector-vector interaction, we study the decays $J/\psi \to \varphi (\omega )f_0(1370)[f_0(1710)]$, $J/\psi \to \varphi (\omega )f_2(1270)[f_2^{\prime }(1525)]$, and $J/\psi \to K^{\ast 0}{\bar{K}}_2^{\ast 0}(1430)$ and make predictions for seven independent ratios that can be done among them. The starting mechanism is that the $J/\psi$ decays into three vectors, followed by the final state interaction of a pair of them. The weights of the different three vector primary channels are obtained from the basic assumption that the $J/\psi$ ($c\bar{c}$) is an SU(3) singlet. By means of only one free parameter we predict four ratios in good agreement with experiment, make two extra predictions for rates yet unmeasured, and disagree on one data for which only upper bounds are reported. Further measurements are most welcome to complete the information required for these ratios that are testing the nature of these resonances as dynamically generated.

    hep-phEPJA(2020)·12 citations
13. 13*

    Investigation of Effects of New Physics in ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ Decay

    Xiao-Long Mu🇨🇳 · Ying Li🇨🇳 · Zhi-Tian Zou🇨🇳 · Bin Zhu🇨🇳

    Recent experimental results of $\mathcal{R}(D^{(\ast )})$ deviate from the standard model (SM) by $3.1\sigma$, suggesting a new physics (NP) that affects the $b\to c\tau {\bar{\nu }}_{\tau }$ transition. Motivated by this, we investigate the possible NP effects in the ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ decay. For this purpose, assuming the neutrinos are left-handed, we calculate in detail the helicity amplitudes of ${\Lambda }_b\to {\Lambda }_c\ell {\bar{\nu }}_{\ell }$ decays with all possible four-fermion operators. Within the latest results of ${\Lambda }_b\to {\Lambda }_c$ form factors from lattice QCD calculations, we study these decays in a model-independent manner. The differential and total branching fractions and other observables are calculated. In SM, we obtain the ratio $\mathcal{R}({\Lambda }_c)=0.33\pm 0.01$. Supposing that NP only affects the third generation fermions, we present the correlations among $\mathcal{R}(D)$, $\mathcal{R}(D^{\ast })$ and $\mathcal{R}({\Lambda }_c)$. We perform a minimum ${\chi }^2$ fit of the wilson coefficient of each operator to the latest experimental data of different observables. It is found that the left-handed scalar operator ${\mathcal{O}}_{SL}$ affects the branching fraction remarkably, and the ratio $\mathcal{R}({\Lambda }_c)$ can be enhanced by $30\%$. For other operators, the ratio amounts to $0.38\pm 0.02$, which is larger than prediction of SM by $20\%$. Using the fitted values of the wilson coefficients of the single NP operators, we also give a prognosis for the physical observables of ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$. Furthermore, we also study the effects of three typical NP models on ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$. We hope our results can be tested in the current LHCb experiment and the future high energy experiments.

    hep-phhep-exPRD(2019)·55 citations
14. 14*

    Suppression of quarkonia in PbPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV

    Vineet Kumar🇮🇳 · Prashant Shukla🇮🇳 · Abhijit Bhattacharyya🇮🇳

    We study different processes responsible for the modification of quarkonia yields in the medium produced in PbPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV. The quarkonia and heavy flavour cross sections are estimated using the measurements in pp collisions at LHC energies and shadowing corrections are obtained using the EPS09 parametrizations. A kinetic model is used which incorporates quarkonia suppression inside the Quark Gluon Plasma (QGP), suppression due to hadronic comovers, and regeneration from recombination of heavy quark pairs. The quarkonia dissociation cross section due to gluon collisions, including both color-electric dipole and color-magnetic dipole transitions, has been employed. The regeneration rate is obtained using the principle of detailed balance. The effect of these processes on the nuclear modification factors for both $\text{Jpsi}$ and ${\rm Y}$ in different ranges of transverse momentum $\text{pT}$ and rapidity has been studied for PbPb collisions at $\text{sNN}=$ 5.02 TeV. The calculations are compared with the available results from LHC experiments. Both the suppression and regeneration due to a QGP are effective in the low and intermediate $\text{pT}$ range. The large observed suppression of $\text{Jpsi}$ at $\text{pT}>$ 10 GeV/$c$ is larger than the suppression expected due to gluon dissociation.

    hep-phnucl-exnucl-thJ.Phys.G(2020)·5 citations
15. 15*

    Diffractive Physics at the LHC

    Maciej Trzebinski🇵🇱

    Diffractive processes possible to be measured at the LHC are listed and briefly discussed. This includes soft (elastic scattering, exclusive meson pair production, diffractive bremsstrahlung) and hard (single and double Pomeron exchange jets, $\gamma$+jet, W/Z, jet-gap-jet, exclusive jets) processes as well as Beyond Stanrad Model phenomena (anomalous gauge couplings, magnetic monopoles).

    hep-phUkr.J.Phys.(2019)·4 citations
16. 16*

    A systematical study of the chiral magnetic effects at the RHIC and LHC energies

    Bang-Xiang Chen🇨🇳 · Sheng-Qin Feng🇨🇳

    Considering the magnetic field response of the QGP medium, we perform a systematical study of the chiral magnetic effect(CME), and make a comparison it with the experimental results for the background-subtracted correlator $H$ at the energies of the RHIC Beam Energy Scan (BES) and LHC energy. The CME signals from our computations show a centrality trend and beam energy dependence that are qualitatively consistent with the experimental measurements of the charge dependent correlations. The time evolution of the chiral electromagnetic current at the RHIC and LHC energies is systematically studied. The dependence of the time-integrated current signal on the beam energy $\sqrt{s}$ with different centralities is investigated. Our phenomenological analysis shows that the time-integrated electromagnetic current is maximal near the collision energy $\sqrt{s}\approx 39$ GeV. The qualitative trend of the induced electromagnetic current is in agreement with the CME experimental results at the RHIC and LHC energies.

    hep-phCPC(2020)·14 citations
17. 17*

    Gluonic vertices and the gluon propagator in Landau gauge Yang-Mills theory

    Markus Q. Huber🇩🇪

    Correlation functions of Landau gauge Yang-Mills theory are calculated from their equations of motion. Solutions for the three- and four-gluon vertices and the role of two-loop diagrams in the gluon propagator equation are discussed.

    hep-phhep-lathep-thActa Phys.Polon.Supp.(2020)·4 citations
18. 18*

    Vacuum polarization corrections to the $n=2$ and $n=3$ levels in muonic ${}^4$He

    Wayne W. Repko🇺🇸 · Stanley F. Radford🇺🇸 · Duane A. Dicus🇺🇸

    The $n=2$ and $n=3$ levels for muonic Helium are calculated using a potential that includes all one-loop and recoil effects. Electronic vacuum polarization corrections are calculated using an extension of Kinoshita and Nio method. For $n=2$, the results are $2p_{1/2}-2s_{1/2}=1375.05\pm 1.4$ meV and $2p_{3/2}-2s_{1/2}=1521.65\pm 1.4$ meV, essentially in agreement with the latest summary of the current calculations. The $n=3$ results are summarized in tabular form and give $3p_{1/2}-3s_{1/2}=394.76\pm 0.43$ meV and $3d_{3/2}-3p_{3/2}=111.40$ meV.

    hep-phPRD(2020)·1 citation
19. 19*

    Dynamical nonextensivity or nonextensive dynamics?

    Jacek Rożynek🇵🇱 · Grzegorz Wilk🇵🇱

    Dense matter is usually described using some kind of mean field theory (MFT) model based on Boltzmann-Gibbs (BG) extensive statistics. However, in many cases the conditions justifying the use of BG statistics are not fulfilled because the systems considered are explicitly nonextensive. In such cases one either enriches the original MFT by adding some dynamical elements violating extensivity (like, for example, long range correlations or intrinsic fluctuations), or one replaces the BG statistics by its nonextensive counterpart characterized by some nonextensivity parameter q 1 (for q -> 1 one returns to the extensive situation). In this work, using a simple quasi-particle description of dense matter (with interaction modelled by effective fugacities, z) we discuss the mutual interplay of non-extensiveness and dynamics (i.e., q and z).

    hep-phEur.Phys.J.ST(2020)·3 citations
20. 20*

    Jets with electrons from boosted top quarks

    Suman Chatterjee🇮🇳 · Rohini Godbole🇮🇳 · Tuhin S. Roy🇮🇳

    We propose a method to identify jets consisting of all the visible remnants of boosted top particles when these decay semileptonically to electrons. Within these jets, the electron shower overlaps with the shower initiated by the $b$ quark, which makes the identification of the electron hard. Even if an electron inside a jet is identified, it is difficult to pinpoint whether the electron rich jet is indeed due to top quark decay or not, since the invisible neutrino carries away a nontrivial part of the energy-momentum of the original top quark. Broadly speaking, the method proposed here has three key components. It uses the distribution of energy in various parts of the detector to identify whether the observed jet is consistent with a jet containing an energetic electron. It uses the substructure of the jet to determine the momentum associated with the electron. Finally, it constructs new variables that carry tell-tale features of top quark decay kinematics using an extra ansatz that, there exists a massless invisible four-momentum \emph{roughly} collimated to the electron, which reconstructs a $W$ and a top when it is combined with the electron and the full jet respectively. We demonstrate the efficacy of this proposal using simulated data and show that our method not only reduces the backgrounds from light flavor jets, $b$ jets from QCD, and hadronic top jets, it can also tell apart jets rich in electrons but not due to top quark decays.

    hep-phhep-exJHEP(2020)·14 citations
21. 21*

    Comment on the article by D. Borah and B. Karmakar "Linear seesaw for Dirac neutrinos with A4 flavour symmetry", Phys. Lett. B789 (2019) 59-70, arXiv: 1806.10685

    V. V. Vien🇻🇳 · H. N. Long🇻🇳 · A. E. Cárcamo Hernández🇨🇱

    D. Borah and B. Karmakar in Phys. Lett. B789 (2019) have proposed an A4 flavoured linear seesaw model to realise light Dirac neutrinos. In this comment article, we show that some neutrino Yukawa interactions were missed in the model, thus implying that a different formula would be needed to determine the effective neutrino mass matrix, with significantly different results. Our result shows that, unlike stated in Phys. Lett. B789 (2019), that the inverted neutrino mass spectrum is not ruled out.

    hep-phPLB(2019)·3 citations
22. 22*

    $\Delta M_s$ theory precision confronts flavour anomalies

    Luca Di Luzio🇮🇹 · Matthew Kirk🇮🇹 · Alexander Lenz🇬🇧 · Thomas Rauh🇨🇭

    Based on recent HQET sum rule and lattice calculations we present updated Standard Model predictions for the mass differences of neutral $B$ mesons: $\Delta M_s^{\mathrm{SM}}=\left(18.4_{-1.2}^{+0.7}\right)\text{mbox}{ps}^{-1}$ and $\Delta M_d^{\mathrm{SM}}=\left(0.533_{-0.036}^{+0.022}\right)\text{mbox}{ps}^{-1}$ and study their impact on new physics models that address the present hints of anomalous data in $b\to s\ell \ell$ transitions. We also examine future prospects of further reducing the theory uncertainties and discuss the implications of a 2025 scenario with $\Delta M_s^{\text{SM 2025}}=\left(18.4\pm 0.5\right)\text{mbox}{ps}^{-1}$. In particular, the latter yields upper bounds $M_{Z^{\prime }}\lesssim 9\text{TeV}$ and $M_{S_3}\lesssim 30\text{TeV}$ for the minimal $Z^{\prime }$ and $S_3$ lepto-quark explanations of the $b\to s\ell \ell$ anomalies, respectively.

    hep-phJHEP(2019)·180 citations
23. 23*

    Clustering of $\bar{B}\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$ kinematic distributions with ClusterKinG

    Jason Aebischer🇩🇪 · Thomas Kuhr🇩🇪 · Kilian Lieret🇩🇪

    New Physics can manifest itself in kinematic distributions of particle decays. The parameter space defining the shape of such distributions can be large which is challenging for both theoretical and experimental studies. Using clustering algorithms, the parameter space can however be dissected into subsets (clusters) which correspond to similar kinematic distributions. Clusters can then be represented by benchmark points, which allow for less involved studies and a concise presentation of the results. We demonstrate this concept using the Python package ClusterKinG, an easy to use framework for the clustering of distributions that particularly aims to make these techniques more accessible in a High Energy Physics context. As an example we consider $\bar{B}\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$ distributions and discuss various clustering methods and possible implications for future experimental analyses.

    hep-phhep-exJHEP(2020)·15 citations
24. 24*

    What if Planet 9 is a Primordial Black Hole?

    Jakub Scholtz🇬🇧 · James Unwin🇺🇸

    We highlight that the anomalous orbits of Trans-Neptunian Objects (TNOs) and an excess in microlensing events in the 5-year OGLE dataset can be simultaneously explained by a new population of astrophysical bodies with mass several times that of Earth ($M_{\oplus }$). We take these objects to be primordial black holes (PBHs) and point out the orbits of TNOs would be altered if one of these PBHs was captured by the Solar System, inline with the Planet 9 hypothesis. Capture of a free floating planet is a leading explanation for the origin of Planet 9 and we show that the probability of capturing a PBH instead is comparable. The observational constraints on a PBH in the outer Solar System significantly differ from the case of a new ninth planet. This scenario could be confirmed through annihilation signals from the dark matter microhalo around the PBH.

    hep-phastro-ph.COastro-ph.EPPRL(2020)·90 citations
25. 25*

    Stability of Axion Dark Matter-Photon Conversion

    Emi Masaki🇯🇵 · Arata Aoki🇯🇵 · Jiro Soda🇯🇵

    It is known that a coherently oscillating axion field is a candidate of the dark matter. In the presence of the oscillating axion, the photon can be resonantly produced through the parametric amplification. In the universe, there also exist cosmological magnetic fields which are coherent electromagnetic fields. In the presence of magnetic fields, an axion can be converted into a photon, and vice versa. Thus, it is interesting to investigate what happens for the axion-photon system in the presence of both the axion dark matter and the magnetic fields. This system can be regarded as a coupled system of the axion and the photon whose equations contain the Mathieu type terms. We find that the instability condition is changed in the presence of magnetic fields in contrast to the conventional Mathieu equation. The positions of bifurcation points between stable and unstable are shifted and new instability bands appear. This is because the resonantly amplified axion can be converted to photon, and vice versa.

    hep-phastro-ph.COhep-thPRD(2020)·25 citations
26. 26*

    Nonperturbative potential for study of quarkonia in QGP

    Dibyendu Bala🇮🇳 · Saumen Datta🇮🇳

    A thermal potential can be defined to facilitate understanding the behavior of quarkonia in quark-gluon plasma. A nonperturbative evaluation of this potential from lattice QCD is difficult, as it involves real-time corelation function, and has often involved the use of Bayesian analysis, with its associated systematics. In this work we show that using the properties of the static quarkonia thermal correlation functions, one can directly extract a thermal potential for quarkonia from Euclidean Wilson loop data. This leads to a controlled extraction, and allows us to judge the suitability of various model potentials. We also discuss the phenomenology of quarkonia in the gluonic plasma.

    ↳ hep-lathep-phPRD(2020)·55 citations
27. 27*

    Multi-TeV flaring from high energy blazars: An evidence of the photohadronic process

    Sarira Sahu🇲🇽 · Carlos E. Lopez Fortin🇲🇽 · Shigehiro Nagataki🇯🇵

    The high energy peaked blazars are known to undergo episodes of flaring in GeV-TeV gamma-rays involving different time scales and the flaring mechanism is not well understood despite long term simultaneous multiwavelength observations. These gamma-rays en route to Earth undergo attenuation by the extra galactic background light. Using the photohadronic model, where the seed photons follow a power-law spectrum and a template extragalactic background light model, we derive a simple relation between the observed multi-TeV gamma-ray flux and the intrinsic flux with a single parameter. We study 42 flaring epochs of 23 blazars and excellent fit to most of the observed spectra are obtained, strengthening the photohadronic origin of multi-TeV gamma-rays. We can also constrain the power spectrum of the seed photons during the flaring period. The blazars of unknown redshifts, whose multi-TeV flaring spectra are known, stringent bounds on the former can be placed using the photohadronic model.

    ↳ astro-ph.HEhep-phApJL(2019)·33 citations
28. 28*

    Dynamics of Revolving D-Branes at Short Distances

    Satoshi Iso🇯🇵 · Noriaki Kitazawa🇯🇵 · Hikaru Ohta🇯🇵 · Takao Suyama🇯🇵

    We study the behavior of the effective potential between revolving D$p$-branes at all ranges of the distance $r$, interpolating $r\gg l_s$ and $r\ll l_s$ ($l_s$ is the string length). Since the one-loop open string amplitude cannot be calculated exactly, we instead employ an efficient method of $partialmodulartransformation$. The method is to perform the modular transformation partially in the moduli parameter and rewrite the amplitude into a sum of contributions from both of the open and closed string massless modes. It is nevertheless free from the double counting and can approximate the open string amplitudes with less than $3\%$ accuracy. From the D-brane effective field theory point of view, this amounts to calculating the one-loop threshold corrections of infinitely many open string massive modes. We show that threshold corrections to the ${\omega }^2{r}^2$ term of the moduli field $r$ cancel among them, where $\omega$ is the angular frequency of the revolution and sets the scale of supersymmetry breaking. This cancellation suggests a possibility to solve the hierarchy problem of the Higgs mass in high scale supersymmetry breaking models.

    ↳ hep-thhep-phJHEP(2020)·2 citations
29. 29*

    Nucleon strange electromagnetic form factors

    C. Alexandrou (Univ. of Cyprus & The Cyprus Inst.)🇨🇾 · S. Bacchio (The Cyprus Inst.)🇨🇾 · M. Constantinou (Temple Univ.)🇺🇸 · J. Finkenrath (The Cyprus Inst.)🇨🇾 · K. Hadjiyiannakou (The Cyprus Inst.)🇨🇾 · K. Jansen (DESY-Zeuthen)🇩🇪 · G. Koutsou (The Cyprus Inst.)🇨🇾

    The role of the strange quarks on the low-energy interactions of the proton can be probed through the strange electromagnetic form factors. Knowledge of these form factors provides essential input for parity-violating processes and contributes to the understanding of the sea quark dynamics. We determine the strange electromagnetic form factors of the nucleon within the lattice formulation of Quantum Chromodynamics using simulations that include light, strange and charm quarks in the sea all tuned to their physical mass values. We employ state-of-the-art techniques to accurately extract the form factors for values of the momentum transfer square up to 0.8~GeV${}^2$. We find that both the electric and magnetic form factors are statistically non-zero. We obtain for the strange magnetic moment ${\mu }^s=-0.017(4)$, the strange magnetic radius $⟨r_M^2{⟩}^s=-0.015(9)$~fm${}^2$, and the strange charge radius $⟨r_E^2{⟩}^s=-0.0048(6)$~fm${}^2$.

    ↳ hep-lathep-phnucl-exnucl-thPRD(2020)·40 citations
30. 30*

    The $ϵ$-regime of dilaton chiral perturbation theory

    Taro V. Brown🇩🇰 · Maarten Golterman🇺🇸 · Svend Krøjer🇩🇰 · Yigal Shamir🇮🇱 · K. Splittorff🇩🇰

    The $ϵ$-regime of dilaton chiral perturbation theory is introduced. We compute the dilaton mass, the chiral condensate and the topological susceptibility in the $ϵ$-regime, as a function of the fermion mass. The microscopic spectral density of the Dirac operator is obtained from dilaton chiral perturbation theory. Our main result is that the chiral condensate and the spectral density are related to their counterparts from ordinary chiral perturbation theory via a simple scaling relation. This relation originates from the mass dependence of the dilaton potential, and is valid in both the $ϵ$-regime and the $p$-regime. In the $ϵ$-regime, moreover, all results agree with the universal predictions to leading order in $ϵ$.

    ↳ hep-lathep-phhep-thPRD(2019)·17 citations
31. 31*

    Oscillon of Ultra-Light Axion-like Particle

    Masahiro Kawasaki🇯🇵 · Wakutaka Nakano🇯🇵 · Eisuke Sonomoto🇯🇵

    Ultra-light axion-like particle (ULAP) is one of attractive candidates for cold dark matter. Because the de Broglie wavelength of ULAP with mass $\sim 10^{-22}\mathrm{eV}$ is $\mathcal{O}(\mathrm{kpc})$, the suppression of the small scale structure by the uncertainty principle can solve the core-cusp problem. Frequently, ULAP is assumed to be uniformly distributed in the present universe. In typical ULAP potentials, however, strong self-resonance at the beginning of oscillation invokes the large fluctuations, which may cause the formation of the dense localized object, oscillon. % Such a dense object lives for a long time, it may affect the cosmological evolution. In this paper, we confirm the oscillon formation in a ULAP potential by numerical simulation and analytically derive its lifetime.

    ↳ astro-ph.COhep-phJCAP(2020)·39 citations
32. 32*

    (Gravitational) Vacuum Cherenkov Radiation

    Marco Schreck🇧🇷

    This work reviews our current understanding of Cherenkov-type processes in vacuum that may occur due to a possible violation of Lorentz invariance. The description of Lorentz violation is based on the Standard Model Extension (SME). To get an overview as general as possible, the most important findings for vacuum Cherenkov radiation in Minkowski spacetime are discussed. After doing so, special emphasis is put on gravitational Cherenkov radiation. For a better understanding, the essential properties of the gravitational SME are recalled in this context. The common grounds and differences of vacuum Cherenkov radiation in Minkowski spacetime and in the gravity sector are emphasized.

    ↳ hep-thhep-phSymmetry(2018)·16 citations
33. 33*

    Formal Developments for Lorentz-Violating Dirac Fermions and Neutrinos

    J.A.A.S. Reis🇧🇷 · M. Schreck🇧🇷

    The current paper is a technical work that is focused on Lorentz violation for Dirac fermions as well as neutrinos, described within the nonminimal Standard-Model Extension. We intend to derive two theoretical results. The first is the full propagator of the single-fermion Dirac theory modified by Lorentz violation. The second is the dispersion equation for a theory of $N$ neutrino flavors that enables the description of both Dirac and Majorana neutrinos. As the matrix structure of the neutrino field operator is very involved for generic $N$, we will use sophisticated methods of linear algebra to achieve our objectives. Our main finding is that the neutrino dispersion equation has the same structure in terms of Lorentz-violating operators as that of a modified single-fermion Dirac theory. The results will be valuable for phenomenological studies of Lorentz-violating Dirac fermions and neutrinos.

    ↳ hep-thhep-phSymmetry(2019)·5 citations
34. 34*

    Trans-Planckian Censorship and the Swampland

    Alek Bedroya🇺🇸 · Cumrun Vafa🇺🇸

    In this paper, we propose a new Swampland condition, the Trans-Planckian Censorship Conjecture (TCC), based on the idea that in a consistent quantum theory of gravity sub-Planckian quantum fluctuations should remain quantum and never become larger than the Hubble horizon and freeze in an expanding universe. TCC leads to conditions that are similar to the refined dS Swampland conjecture. For example, applied to the case of cosmologies driven only by a scalar field, the TCC imposes an upper bound of $2/\sqrt{d-2}$ on the asymptotic value of $|V^{\prime }|/V$. Additionally, it implies that a monotonically decreasing potential across $[{\varphi }_1,{\varphi }_2]$ satisfies $V({\varphi }_2)\le A\cdot \exp (-2({\varphi }_2-{\varphi }_1))/\sqrt{(d-1)(d-2)})$ for some $\mathcal{O}(1)$ constant $A$. Like the dS Swampland conjecture, the TCC forbids long-lived meta-stable dS spaces, but allows sufficiently short-lived ones.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2020)·489 citations
35. 35*

    How sound are our ultra-light axion approximations?

    Tessa Cookmeyer · Daniel Grin · Tristan L. Smith

    Ultra-light axions (ULAs) are a promising dark-matter candidate. ULAs may have implications for small-scale challenges to the $\Lambda$CDM model, and arise in string scenarios. ULAs are already constrained by cosmic microwave background (CMB) experiments and large-scale structure surveys, and will be probed with much greater sensitivity by future efforts. It is challenging to compute observables in ULA scenarios with sufficient speed and accuracy for cosmological data analysis because the ULA field oscillates rapidly. In past work, an effective fluid approximation has been used to make these computations feasible. Here this approximation is tested against an exact solution of the ULA equations, comparing the induced error of CMB observables with the sensitivity of current and future experiments. In the most constrained mass range for a ULA dark matter component ($10^{-27}\mathrm{eV}\le m_{\mathrm{ax}}\le 10^{-25}\mathrm{eV}$), the induced bias on the allowed ULA fraction of dark matter from Planck data is less than $1\sigma$. In the cosmic-variance limit (including temperature and polarization data), the bias is $\lesssim 2\sigma$ for primary CMB anisotropies, with more severe biases (as high as $\sim 4\sigma$) resulting for less reliable versions of the effective fluid approximation. If all of the standard cosmological parameters are fixed by other measurements, the expected bias rises to $4-20\sigma$ (well beyond the validity of the Fisher approximation), though the required level of degeneracy breaking will not be achieved by any planned surveys.

    ↳ astro-ph.COgr-qchep-phPRD(2020)·32 citations
36. 36*

    Resonance Electroproduction and the Origin of Mass

    Craig D. Roberts🇨🇳

    One of the greatest challenges within the Standard Model is to discover the source of visible mass. Indeed, this is the focus of a "Millennium Problem", posed by the Clay Mathematics Institute. The answer is hidden within quantum chromodynamics (QCD); and it is probable that revealing the origin of mass will also explain the nature of confinement. In connection with these issues, this perspective describes insights that have recently been drawn using contemporary methods for solving the continuum bound-state problem in relativistic quantum field theory and how they have been informed and enabled by modern experiments on nucleon-resonance electroproduction.

    ↳ nucl-thhep-lathep-phnucl-exEPJ Web Conf.(2020)·8 citations
37. 37*

    Trans-Planckian Censorship and Inflationary Cosmology

    Alek Bedroya🇺🇸 · Robert Brandenberger🇨🇦 · Marilena Loverde🇺🇸 · Cumrun Vafa🇺🇸

    We study the implications of the recently proposed Trans-Planckian Censorship Conjecture (TCC) for early universe cosmology and in particular inflationary cosmology. The TCC leads to the conclusion that if we want inflationary cosmology to provide a successful scenario for cosmological structure formation, the energy scale of inflation has to be lower than $10^9$ GeV. Demanding the correct amplitude of the cosmological perturbations then forces the generalized slow-roll parameter $ϵ$ of the model to be very small ($<10^{-31}$). This leads to the prediction of a negligible amplitude of primordial gravitational waves. For slow-roll inflation models, it also leads to severe fine tuning of initial conditions.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2020)·275 citations
38. 38*

    Lev Lipatov: my friend and renowned physicist

    Eugene Levin (Rev AvivU./UTFSM)🇮🇱

    These notes are written for the book "From the past to the future: the legacy of Lev Lipatov", editors: Jochen Bartels et all, which will be published by WS. I tried to share with you the atmosphere and the flavour of everyday life in Gribov's theory department, where Lev matured as an independent researcher and wrote all his breakthrough papers.

    ↳ physics.hist-phhep-phhep-th1 citation
39. 39*

    Binary Pulsars as probes for Spin-2 Ultralight Dark Matter

    Juan Manuel Armaleo🇦🇷 · Diana López Nacir🇦🇷 · Federico R.Urban🇨🇿

    Binary pulsars can be excellent probes of ultra-light dark matter. We consider the scenario where the latter is represented by a spin-2 field. The coherent oscillations of the dark matter field perturb the dynamics of binary systems, leading to secular effects for masses that resonate with the binary systems. For the range $10^{-23}$eV $\lesssim m\lesssim 10^{-17}$eV we show that current timing data could potentially constrain the universal coupling strength of dark matter to ordinary matter at the level of $\alpha \simeq 10^{-5}$.

    ↳ astro-ph.HEastro-ph.COgr-qchep-phJCAP(2020)·40 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.