Mon·Mar 16, 2020Monday·March 16, 2020

1. 01*

   LHC at 10: the physics legacy

   Michelangelo Mangano🇨🇭

   Ten years into the LHC physics programme, I reflect on the vast amount of extraordinary results that have emerged so far.

   hep-phhep-exhep-thCERN Cour.(2020)·9 citations
2. 02*

   Active neutrino oscillations and double beta decay characteristics with sterile neutrinos contributions

   V. V. Khruschov🇷🇺 · S. V. Fomichev🇷🇺 · S. V. Semenov🇷🇺

   Light sterile neutrinos contributions both for active neutrinos oscillations and neutrinoless double beta decay characteristics are estimated in the framework of the phenomenological model with three active and three sterile neutrinos assuming the Majorana nature of neutrino. Appearance and survival probabilities for active neutrinos with contributions of eV-sterile neutrinos in application to the short-baseline anomalies in neutrino data are obtained at the same test values of the model parameters. Modified graphical dependences for the survival probability of electron neutrinos/antineutrinos and the probability of appearance of electron neutrinos/antineutrinos in muon neutrino/antineutrino beams as functions of distance and other model parameters at different neutrino energies, and also as functions of the ratio of the distance to the neutrino energy are presented. A significant difference was found between the probability curves of the considered neutrino model and the simple sinusoidal curves of the neutrino model with one sterile neutrino. Effective electron neutrino masses for the beta decay and the neutrinoless double beta decay are estimated with account of eV-sterile neutrinos contributions. Besides, the two-neutrino double beta decay characteristics for selenium-82 are calculated. These findings can be used for interpretation and prediction of results of ground-based experiments on search for the sterile neutrinos as well as the neutrinoless double beta decay.

   hep-phPhys.Atom.Nucl.(2021)·3 citations
3. 03*

   Revisiting wrong sign Yukawa coupling of type II two-Higgs-doublet model in light of the recent LHC data

   Lei Wang · Hong-Xin Wang · Xiao-Fang Han

   In light of the recent LHC Higgs data, we examine the parameter space of type II two-Higgs-doublet model in which the 125 GeV Higgs has the wrong sign Yukawa couplings. Combining related theoretical and experimental limits, we find that the LHC Higgs data exclude most of the parameter space of the wrong sign Yukawa coupling. For $m_H=$ 600 GeV, the allowed samples are mainly distributed in several corners and narrow bands of m_A<20 GeV, 30 GeV<m_A<120 GeV, 240 GeV<m_A<300 GeV, 380 GeV <m_A<430 GeV, and 480 GeV<m_A<550 GeV. For m_A=600 GeV, m_H is required to be less than 470 GeV. The light pseudo-scalar with a mass of 20 GeV is still allowed in case of the wrong sign Yukawa coupling of 125 GeV Higgs.

   hep-phCPC(2020)·19 citations
4. 04*

   LFV and g-2 in non-universal SUSY models with light higgsinos

   Chengcheng Han🇰🇷 · M.L. López-Ibáñez🇨🇳 · Aurora Melis🇪🇸 · Óscar Vives🇪🇸 · Lei Wu🇨🇳 · Jin Min Yang🇨🇳

   We consider a supersymmetric type-I seesaw framework with non-universal scalar masses at the GUT scale to explain the long-standing discrepancy of the anomalous magnetic moment of the muon. We find that it is difficult to accommodate the muon g-2 while keeping charged-lepton flavor violating processes under control for the conventional SO(10)-based relation between the up sector and neutrino sector. However, such tension can be relaxed by adding a Georgi-Jarlskog factor for the Yukawa matrices, which requires a non-trivial GUT-based model. In this model, we find that both observables are compatible for small mixings, CKM-like, in the neutrino Dirac Yukawa matrix.

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

   Bottomonia production and polarization in the NRQCD with $k_T$-factorization. II: ${\rm Y}(2S)$ and ${\chi }_b(2P)$ mesons

   N.A. Abdulov🇷🇺 · A.V. Lipatov🇷🇺

   The ${\rm Y}(2S)$ production and polarization at high energies is studied in the framework of $k_T$-factorization approach. Our consideration is based on the non-relativistic QCD formalism for bound states formation and off-shell production amplitudes for hard partonic subprocesses. The direct production mechanism, feed-down contributions from radiative ${\chi }_b(3P)$ and ${\chi }_b(2P)$ decays and contributions from ${\rm Y}(3S)$ decays are taken into account. The transverse momentum dependent gluon densities in a proton were derived from the Ciafaloni-Catani-Fiorani-Marchesini evolution equation as well as from the Kimber-Martin-Ryskin prescription. Treating the non-perturbative color octet transitions in terms of the mulitpole radiation theory, we extract the corresponding non-perturbative matrix elements for ${\rm Y}(2S)$ and ${\chi }_b(2P)$ mesons from a combined fit to ${\rm Y}(2S)$ transverse momenta distributions measured by the CMS and ATLAS Collaborations at the LHC energies $\sqrt{s}=7$ and $13$ TeV and from the relative production rate $R_{{\rm Y}(2S)}^{{\chi }_b(2P)}$ measured by the LHCb Collaboration at $\sqrt{s}=7$ and $8$ TeV. Then we apply the extracted values to investigate the polarization parameters ${\lambda }_{\theta }$, ${\lambda }_{\varphi }$ and ${\lambda }_{\theta \varphi }$, which determine the ${\rm Y}(2S)$ spin density matrix. Our predictions have a good agreement with the currently available data within the theoretical and experimental uncertainties.

   hep-phEPJC(2020)·7 citations
6. 06*

   Vacuum Decay in the Standard Model: Analytical Results with Running and Gravity

   J.R. Espinosa🇪🇸

   A tunneling bounce driving the decay of a metastable vacuum must respect an integral constraint dictated by simple scaling arguments that is very useful to determine key properties of the bounce. After illustrating how this works in a simple toy model, the Standard Model Higgs potential is considered, including quartic coupling running and gravitational corrections as sources of scale invariance breaking. This approach clarifies the existence of the bounce and leads to simple and accurate analytical results in an expansion in the breaking parameters. Using the so-called tunneling-potential approach (generalized for nonminimal coupling to gravity) the integral constraint and the tunneling action are extended to second order in perturbations.

   hep-phJCAP(2020)·25 citations
7. 07*

   Meson-baryon scattering in resummed baryon chiral perturbation theory using time-ordered perturbation theory

   X.-L. Ren🇩🇪 · E. Epelbaum🇩🇪 · J. Gegelia🇩🇪 · Ulf-G. Meißner🇩🇪

   Integral equations for meson-baryon scattering amplitudes are obtained by utilizing time-ordered perturbation theory for a manifestly Lorentz-invariant formulation of baryon chiral perturbation theory. Effective potentials are defined as sums of two-particle irreducible contributions of time-ordered diagrams and the scattering amplitudes are obtained as solutions of integral equations. Ultraviolet renormalizability is achieved by solving integral equations for the leading order amplitude and including higher order corrections perturbatively. As an application of the developed formalism, pion-nucleon scattering is considered.

   hep-phnucl-thEPJC(2020)·8 citations
8. 08*

   LHC Hunting the Odderon: Is It Really Catched?

   Vladimir A. Petrov🇷🇺

   We give a short survey of recent LHC experiments and related theory topics concerning the Odderon problem.

   hep-ph1 citation
9. 09*

   Bridging resonant leptogenesis and low-energy CP violation with an RGE-modified seesaw relation

   Zhi-zhong Xing🇨🇳 · Di Zhang🇨🇳

   We propose a special type-I seesaw scenario in which the Yukawa coupling matrix $Y_{\nu }^{}$ can be fully reconstructed by using the light Majorana neutrino masses $m_i^{}$, the heavy Majorana neutrino masses $M_i^{}$ and the PMNS lepton flavor mixing matrix $U$. It is the RGE-induced correction to the seesaw relation that helps interpret the observed baryon-antibaryon asymmetry of the Universe via flavored resonant thermal leptogenesis with $M_1^{}\simeq M_2^{}\ll M_3^{}$. We show that our idea works well in either the $\tau$-flavored regime with equilibrium temperature $T\simeq M_1^{}\in (10^9,10^{12}]$ GeV or the $(\mu +\tau )$-flavored regime with $T\simeq M_1^{}\in (10^5,10^9]$ GeV, provided the light neutrinos have a normal mass ordering. We find that the same idea is also viable for a {\it minimal} type-I seesaw model with two nearly degenerate heavy Majorana neutrinos.

   hep-phhep-exPLB(2020)·19 citations
10. 10*

    New approach to neutrino masses and leptogenesis with Occam's razor

    D. M. Barreiros🇵🇹 · F. R. Joaquim🇵🇹 · T. T. Yanagida🇨🇳

    The minimal type-I seesaw framework with texture-zero Yukawa and mass matrices inspired by Occam's razor is incompatible with normally-ordered neutrino masses (currently preferred by data) when lepton mixing originates solely from the neutrino sector. Moreover, the lightest right-handed neutrino mass required to generate the observed baryon asymmetry of the Universe via leptogenesis ($M_1\sim 10^{14}$ GeV) is in conflict with vanilla scenarios for Peccei-Quinn) axion dark matter where the reheating temperature of the Universe is typically below $10^{12}$ GeV. In this work, we present a new Occam's razor setup which overcomes these problems by including charged-lepton mixing parametrized by a single angle, which is predicted to be very close to the quark Cabibbo angle. Furthermore, the atmospheric mixing angle lies in the second octant and the leptogenesis scale is lowered to $\sim 5.5\times 10^{10}$ GeV, lifting the tension with the axion dark-matter hypothesis.

    hep-phPRD(2020)·15 citations
11. 11*

    Fully coherent energy loss effects on light hadron production in pA collisions

    François Arleo🇫🇷 · Florian Cougoulic🇺🇸 · Stéphane Peigné🇫🇷

    We single out the role of fully coherent induced gluon radiation on light hadron production in pA collisions. The effect has the same general features as for quarkonium production, however with a richer color structure as the induced radiation depends on the global color charge of the partonic subprocess final state. Baseline predictions for light hadron nuclear suppression in pPb collisions at the LHC are provided, taking into account only the effect of fully coherent energy loss, which proves to be of the same order of magnitude as gluon shadowing or saturation. This underlines the need to include fully coherent energy loss in phenomenological studies of hadron production in pA collisions.

    hep-phJHEP(2020)·29 citations
12. 12*

    Momentum Anisotropy of Leptons from Two Photon Processes in Heavy Ion Collisions

    Bo-Wen Xiao🇨🇳 · Feng Yuan🇺🇸 · Jian Zhou🇨🇳

    We investigate the azimuthal angular correlation between the lepton transverse momentum $P_{\perp }$ and the impact parameter $b_{\perp }$ in non-central heavy-ion collisions, where the leptons are produced through two-photon scattering. Among the Fourier harmonic coefficients, a significant $v_4$ asymmetry is found for the typical kinematics at RHIC and LHC with a mild dependence on the $P_{\perp }$, whereas $v_2$ is power suppressed by the lepton mass over $P_{\perp }$. This unique prediction, if confirmed from the experiments, shall provide crucial information on the production mechanism for the dilepton in two-photon processes.

    hep-phhep-exnucl-exnucl-thPRL(2020)·37 citations
13. 13*

    Constraining SMEFT operators with associated $h\gamma$ production in Weak Boson Fusion

    Anke Biekötter🇬🇧 · Raquel Gomez-Ambrosio🇬🇧 · Parisa Gregg🇬🇧 · Frank Krauss🇬🇧 · Marek Schönherr🇬🇧

    We consider the associated production of a Higgs boson and a photon in weak boson fusion in the Standard Model (SM) and the Standard Model Effective Theory (SMEFT), with the Higgs boson decaying to a pair of bottom quarks. Analysing events in a cut-based analysis and with multivariate techniques we determine the sensitivity of this process to the bottom-Yukawa coupling in the SM and to possible CP-violation mediated by dimension-6 operators in the SMEFT.

    hep-phPLB(2021)·24 citations
14. 14*

    Semiclassical Approximation meets Keldysh-Schwinger diagrammatic technique: Scalar ${\phi }^4$

    A.A. Radovskaya🇷🇺 · A.G. Semenov🇷🇺

    We study the evolution of the non-equilibrium quantum fields from a highly excited initial state in two approaches: the standard Keldysh-Schwinger diagram technique and the semiclassical expansion. We demonstrate explicitly that these two approaches coincide if the coupling constant $g$ and the Plank constant $\hslash$ are small simultaneously. Also, we discuss loop diagrams of the perturbative approach, which are summed up by the leading order term of the semiclassical expansion. As an example, we consider shear viscosity for the scalar field theory at the leading semiclassical order. We introduce the new technique that unifies both semiclassical and diagrammatic approaches and open the possibility to perform the resummation of the semiclassical contributions.

    hep-phcond-mat.stat-mechhep-thnucl-thEPJC(2021)·23 citations
15. 15*

    Comments on a new `full colour' parton shower

    Jack Holguin🇬🇧 · Jeffrey R. Forshaw🇬🇧 · Simon Plätzer🇦🇹

    A new parton shower algorithm has been presented with the claim of providing soft-gluon resummation at `full colour' (arXiv:2001.11492). In this paper we show that the algorithm does not succeed in this goal. We show that full colour accuracy requires the Sudakov factors to be defined at amplitude level and that the simple parton-shower unitarity argument employed in arXiv:2001.11492 is not sufficient.

    hep-phhep-ex10 citations
16. 16*

    Building a consistent parton shower

    Jeffrey R. Forshaw🇬🇧 · Jack Holguin🇬🇧 · Simon Plätzer🇦🇹

    Modern parton showers are built using one of two models: dipole showers or angular ordered showers. Both have distinct strengths and weaknesses. Dipole showers correctly account for wide-angle, soft gluon emissions and track the leading flows in QCD colour charge but they are known to mishandle partonic recoil. Angular ordered showers keep better track of partonic recoil and correctly include large amounts of wide-angle, soft physics but azimuthal averaging means they are known to mishandle some correlations. In this paper, we derive both approaches from the same starting point; linking our understanding of the two showers. This insight allows us to construct a new dipole shower that has all the strengths of a standard dipole shower together with those of an angular ordered shower. We show that this new approach corrects the next-to-leading-log errors previously observed in parton showers and improves their sub-leading-colour accuracy.

    hep-phhep-exJHEP(2020)·131 citations
17. 17*

    DPS mechanism for associated $c\bar{c}b\bar{b}$ production in $AA$ UPCs

    Edgar Huayra🇧🇷 · Emmanuel G. de Oliveira🇧🇷 · Roman Pasechnik🇸🇪

    We discuss the associated $c\bar{c}$ and $b\bar{b}$ quark pairs production in the double-parton scattering (DPS) process in ultraperipheral (UPCs) $AA$ collisions. We derive an analogue of the inclusive DPS pocket formula and the photon-energy dependent effective cross section considering an overlap between the hard SPS scatterings. We provide numerical predictions for the DPS cross sections for the $c\bar{c}b\bar{b}$ production process at the typical energies of $AA$ UPCs at the LHC and FCC colliders and also characterize the $A$ dependence of the total UPC DPS cross section.

    hep-phEPJC(2020)·7 citations
18. 18*

    Fifth Force and Hyperfine Splitting in Bound Systems

    Ulrich D. Jentschura🇺🇸

    Two recent experimental observations at the ATOMKI Institute of the Hungarian Academy of Sciences (regarding the angular emission pattern of electron-positron pairs from nuclear transitions from excited states in 8Be and 4He) indicate the possible existence of a particle of a rest mass energy of roughly 17 MeV. The so-called X17 particle constitutes a virtual state in the process, preceding the emission of the electron-positron pair. Based on the symmetry of the nuclear transitions ($1^{+}$ to $0^{+}$ and $0^{-}$ to $0^{+}$), the X17 could either be a vector, or a pseudoscalar particle. Here, we calculate the effective potentials generated by the X17, for hyperfine interactions in simple atomic systems, for both the pseudoscalar as well as the vector X17 hypotheses. The effective Hamiltonians are obtained in a general form which is applicable to both electronic as well as muonic bound systems. The effect of virtual annihilation and its contribution to the hyperfine splitting also is considered. Because of the short range of the X17-generated potentials, the most promising pathway for the observation of the X17-mediated effects in bound systems concerns hyperfine interactions, which, for $S$ states, are given by modifications of short-range (Dirac-delta) potentials in coordinate space. For the pseudoscalar hypothesis, the exchange of one virtual X17 quantum between the bound lepton and the nucleus exclusively leads to hyperfine effects, but does not affect the Lamb shift. Effects due to the X17 are shown to be drastically enhanced for muonic bound systems. Prospects for the detection of hyperfine effects mediated by X17 exchange are analyzed for muonic deuterium, muonic hydrogen, muonium, true muonium (${\mu }^{+}{\mu }^{-}$ bound system), and positronium.

    hep-phphysics.atom-phPRA(2020)·11 citations
19. 19*

    Fibre inflation and precision CMB data

    Sukannya Bhattacharya🇮🇳 · Koushik Dutta🇮🇳 · Mayukh Raj Gangopadhyay🇮🇳 · Anshuman Maharana🇮🇳 · Kajal Singh🇮🇳

    Generic features of models of inflation obtained from string compactifications are the correlations between the model parameters and the postinflationary evolution of the universe. Thus, the postinflationary evolution depends on the inflationary model parameters and accurate inflationary predictions require that this be incorporated in the evolution of the primordial spectrum. The fibre inflation model is a promising model of inflation constructed in type IIB string theory. This model has two interesting features in its postinflationary evolution. The reheating temperature of the model is directly correlated with the model parameters. The model also necessarily predicts some dark radiation, which can be sizable for certain choices of discrete parameters in the model. We analyze this model in detail using publicly available codes - ModeChord and CosmoMC with the latest Planck+BICEP2/Keck array data to constrain the model parameters and $N_{\mathrm{pivot}}$ (the number of $e$-foldings between horizon exit of the CMB pivot mode and the end of inflation). We also carry out the same analysis using the publicly available code Cobaya. We find the results of both the analysis to be in agreement. Our analysis provides the basic methods necessary to extract precise inflationary prediction in string models incorporating correlations between model parameters and postinflationary evolution.

    ↳ astro-ph.COhep-phhep-thPRD(2020)·19 citations
20. 20*

    Collins-Soper Kernel for TMD Evolution from Lattice QCD

    Phiala Shanahan🇺🇸 · Michael Wagman🇺🇸 · Yong Zhao🇺🇸

    The Collins-Soper kernel relates transverse momentum-dependent parton distribution functions (TMDPDFs) at different energy scales. For small parton transverse momentum $q_T\sim {\Lambda }_{\text{QCD}}$, this kernel is non-perturbative and can only be determined with controlled uncertainties through experiment or first-principles calculations. This work presents the first exploratory determination of the Collins-Soper kernel using the lattice formulation of Quantum Chromodynamics. In a quenched calculation, the $N_f=0$ kernel is determined at scales in the range 250 MeV $<q_T<2$ GeV, and an analysis of the remaining systematic uncertainties is undertaken.

    ↳ hep-lathep-phnucl-thPRD(2020)·137 citations
21. 21*

    New class of violation of local constant field approximation in intense crossed laser pulse scenarios

    E. Raicher🇩🇪 · Q.Z. Lv🇩🇪 · C.H. Keitel🇩🇪 · K.Z. Hatsagortsyan🇩🇪

    It is commonly assumed that in ultrastrong laser fields, when the strong field parameter of the laser field $\xi$ is larger than one, the electron radiation is well described by the local constant field approximation (LCFA). We discuss the failure of this conjecture, considering radiation of an ultrarelativistic electron interacting with strong counterpropagating laser waves. A deviation from LCFA, in particular in the high-frequency domain, is shown to occur even at $\xi \gg 1$ because of the appearance of an additional small time scale in the trajectory. Moreover, we identify a new class of LCFA violation, when the radiation formation length becomes smaller than the one via LCFA. It is characterized by a broad and smooth spectrum rather than an harmonic structure. A similar phenomenon is also demonstrated in the scenario of an electron colliding with an ultrashort laser pulse. The relevance to laser-plasma kinetic simulations is discussed.

    ↳ physics.plasm-phhep-phPRResearch(2021)·20 citations
22. 22*

    Surface waves in a collisional quark-gluon plasma

    K. Baiseitov🇰🇿 · Z. A. Moldabekov🇰🇿 · D. Blaschke🇷🇺 · N. Djienbekov🇰🇿 · T. S. Ramazanov🇰🇿

    Surface waves propagating in the semi-bounded collisional hot QCD medium (quark-gluon plasma) are considered. To investigate the effect of collisions as damping and non-ideality factor, the longitudinal and transverse dielectric functions of the quark-gluon plasma are used within the Bhatnagar-Gross-Krook (BGK) approach. The results were obtained both analytically and numerically in the long wavelength limit. First of all, collisions lead to smaller values of surface wave frequency and their stronger damping. Secondly, the results show that non-ideality leads to the appearance of a new branch of surface waves compared to the collisionless case. The relevance of the surface excitations (waves) for the QGP realized in experiments is discussed.

    ↳ physics.plasm-phhep-phPhys.Part.Nucl.Lett.(2020)·3 citations
23. 23*

    Gravity in the Era of Equality: Towards solutions to the Hubble problem without fine-tuned initial conditions

    Miguel Zumalacarregui🇩🇪

    Discrepant measurements of the Universe's expansion rate ($H_0$) may signal physics beyond the standard cosmological model. Here I describe two early modified gravity mechanisms that reconcile the value of $H_0$ by increasing the expansion rate in the era of matter-radiation equality. These mechanisms, based on viable Horndeski theories, require significantly less fine-tuned initial conditions than early dark energy with oscillating scalar fields. In Imperfect Dark Energy at Equality (IDEE), the initial energy density dilutes slower than radiation but faster than matter, naturally peaking around the era of equality. The minimal IDEE model, a cubic Galileon, is too constrained by the cosmic microwave background (Planck) and baryon acoustic oscillations (BAO) to relieve the $H_0$ tension. In Enhanced Early Gravity (EEG), the scalar field value modulates the cosmological strength of gravity. The minimal EEG model, an exponentially coupled cubic Galileon, gives a Planck+BAO value $H_0=68.7\pm 1.5$ (68\% c.l.), reducing the tension with SH0ES from $4.4\sigma$ to $2.6\sigma$. Additionally, Galileon contributions to cosmic acceleration may reconcile $H_0$ via Late-Universe Phantom Expansion (LUPE). Combining LUPE, EEG and $\Lambda$ reduces the tension between Planck, BAO and SH0ES to $2.5\sigma$. I will also describe additional tests of coupled Galileons based on local gravity tests, primordial element abundances and gravitational waves. While further model building is required to fully resolve the $H_0$ problem and satisfy all available observations, these examples show the wealth of possibilities to solve cosmological tensions beyond Einstein's General Relativity.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2020)·128 citations
24. 24*

    The Halo Void (Dust) Model of Large Scale Structure

    Rodrigo Voivodic🇧🇷 · Henrique Rubira🇩🇪 · Marcos Lima🇧🇷

    Within the Halo Model of large scale structure, all matter is contained in dark matter halos. This simple yet powerful framework has been broadly applied to multiple data sets and enriched our comprehension of how matter is distributed in the Universe. In this work we extend this assumption by allowing for matter to rest not only inside halos but also within cosmic voids and in between halos and voids (which we call 'dust'). This assumption leads to additional contributions (1Void, 2Void, Halo-Void, etc.) to the predictions of correlation functions, spectra and profiles for both halos and voids. Whereas the Halo Model can only make predictions for halo quantities, the Halo Void Model extends those for void statistics and halo-void cross-correlations. We provide recipes for all new ingredients of the Halo Void (Dust) Model, such as the void abundance, linear bias and density profile and test their validity in a N-body simulation. Including voids and dust into the calculations improves the transition between the 1Halo and the 2Halo terms by up to $\sim 6\%$. It also eliminates the need to include low-mass structures on the normalization of large-scale terms, suggesting that halos and voids are complementary cosmic structures to effectively describe matter distribution on large scales of the Universe.

    ↳ astro-ph.COgr-qchep-phJCAP(2020)·34 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.