Tue·Mar 3, 2020Tuesday·March 3, 2020

1. 01*

   $CP$ violation from $\tau$, $t$ and $b$ dimension-6 Yukawa couplings -- interplay of baryogenesis, EDM and Higgs physics

   Elina Fuchs🇮🇱 · Marta Losada🇦🇪 · Yosef Nir🇮🇱 · Yehonatan Viernik🇮🇱

   We explore the implications of the Standard Model effective field theory (SMEFT) with dimension-six terms involving the Higgs boson and third-generation fermion fields on the rate of Higgs boson production and decay into fermions, on the electric dipole moments (EDMs) of the electron, and on the baryon asymmetry of the Universe. We study the consequences of allowing these additional terms for each flavor separately and for combinations of two flavors. We find that a complex $\tau$ Yukawa coupling can account for the observed baryon asymmetry $Y_B^{\mathrm{obs}}$ within current LHC and EDM bounds. A complex $b$ ($t$) Yukawa coupling can account for $4\%$ ($2\%$) of $Y_B^{\mathrm{obs}}$, whereas a combination of the two can reach $12\%$. Combining $\tau$ with either $t$ or $b$ enlarges the viable parameter space owing to cancellations in the EDM and in either Higgs production times decay or the total Higgs width, respectively. Interestingly, in such a scenario there exists a region in parameter space where the SMEFT contributions to the electron EDM cancel and collider signal strengths are precisely SM-like, while producing sufficient baryon asymmetry. Measuring $CP$ violation in Higgs decays to $\tau$ leptons is the smoking gun for this scenario.

   hep-phastro-ph.COhep-exJHEP(2020)·68 citations
2. 02*

   Reply to Robinson and Michaud, arXiv:2002.08893

   Noah Kurinsky🇺🇸 · Daniel Baxter🇺🇸 · Yonatan Kahn🇺🇸 · Gordan Krnjaic🇺🇸 · Peter Abbamonte🇺🇸

   We respond to Robinson and Michaud's (RM) comment (arXiv:2002.08893) on our recent preprint arXiv:2002.06937, in which we discuss recent excesses in low-threshold dark matter searches, and offer a potential unifying dark matter interpretation. We thank RM for their feedback, which highlights the critical need for future measurements to directly calibrate plasmon charge yields for low $\sim$ 10 eV energy depositions. RM objected to our assertion that plasmons generated at energy scales below 100~eV may have a large branching fraction into phonons. As we argue below, the points raised by RM do not invalidate our primary conclusions, as they pertain to a much different energy scale than we discuss in our paper.

   hep-phastro-ph.COcond-mat.mtrl-scihep-ex+14 citations
3. 03*

   Quantum Kinetic Equation for spin polarization of massive quarks from pQCD

   Shiyong Li🇺🇸

   We review the recent progress in formulating a quantum kinetic theory for the polarization of spin-$\frac{1}{2}$ massive quarks from the leading-log order of perturbative QCD.

   hep-phnucl-thNPA(2021)·2 citations
4. 04*

   Gluon Shadowing and Nuclear Entanglement

   Paolo Castorina🇮🇹 · Alfredo Iorio🇨🇿 · Daniele Lanteri🇮🇹 · Petr Lukes🇨🇿

   Relying on previous results that link entanglement entropy and parton distribution functions in deep inelastic scattering and focusing on the small Bjorken scaling region we present here indications that gluon shadowing might indeed be explained as due to a depletion of the entanglement entropy between observed and unobserved degrees of freedom per nucleon within a nucleus with respect to the free nucleon case. We apply to gluon shadowing the general Page approach to the calculation of the entanglement entropy in bipartite systems, giving physical motivations of the results.

   hep-phhep-thquant-phIJMPE(2021)·10 citations
5. 05*

   Application of dilaton chiral perturbation theory to $N_f=8$, $\mathrm{SU}(3)$ spectral data

   Maarten Golterman🇺🇸 · Ethan T. Neil🇺🇸 · Yigal Shamir🇮🇱

   We extend dilaton chiral perturbation theory (dChPT) to include the taste splittings in the Nambu--Goldstone sector observed in lattice simulations of near-conformal theories with staggered fermions. We then apply dChPT to a recent simulation by the LSD collaboration of the SU(3) gauge theory with 8 fermions in the fundamental representation, which is believed to exhibit near-conformal behavior in the infrared, and in which a light singlet scalar state, nearly degenerate with the pions, has been found. We find that the mesonic sector of this theory can be successfully described by dChPT, including, in particular, the mesonic taste splittings found in the simulation. We confirm that current simulations of this theory are in the "large-mass" regime.

   hep-phhep-lathep-thPRD(2020)·50 citations
6. 06*

   Analysis of Bose-Einstein correlation at 7 TeV by LHCb collaboration based on stochastic approach

   Takuya Mizoguchi🇯🇵 · Minoru Biyajima🇯🇵

   The Bose-Einstein correlation (BEC) in forward region ($2.0<\eta <4.8$) measured at 7 TeV in the Large Hadron Collider (LHC) by the LHCb collaboration is analyzed using two conventional formulas of different types named CF${}_{\mathrm{I}}$ and CF${}_{\mathrm{II}}$. The first formula is well known and contains the degree of coherence ($\lambda$) and the exchange function $E_{\mathrm{BE}}^2$ from the BE statistics. The second formula is an extended formula (CF${}_{\mathrm{II}}$) that contains the second degree of coherence ${\lambda }_2$ and the second exchange function $E_{\mathrm{B}{\mathrm{E}}_2}^2$ in addition to CF${}_{\mathrm{I}}$. To examine the physical meaning of the parameters estimated by CF${}_{\mathrm{II}}$, we analyze the LHCb BEC data by using a stochastic approach of the three-negative binomial distribution and the three-generalized Glauber-Lachs formula. Our results reveal that the BEC at 7 TeV consisted of three activity intervals defined by the multiplicity $n$ ([8, 18], [19, 35], and [36, 96]) can be well explained by CF${}_{\mathrm{II}}$.

   hep-phhep-exnucl-thInt.J.Mod.Phys.A(2020)·4 citations
7. 07*

   A direct link between unflavored leptogenesis and low-energy CP violation via the one-loop quantum corrections

   Zhi-zhong Xing🇨🇳 · Di Zhang🇨🇳

   In the type-I seesaw mechanism the Casas-Ibarra (CI) parametrization provides a convenient description of the Dirac neutrino mass matrix in terms of the light and heavy Majorana neutrino masses, the lepton flavor mixing matrix $U$ and an unknown complex orthogonal matrix $O$. If $O$ is assumed to be real, it will be impossible to generate {\it unflavored} thermal leptogenesis via the lepton-number-violating and CP-violating decays of the lightest heavy Majorana neutrino. We find that this observation can be invalidated after small but unavoidable quantum corrections to the CI parametrization are taken into account with the help of the one-loop renormalization-group equations (RGEs) between the seesaw and electroweak scales. We illustrate a novel and viable unflavored leptogenesis scenario of this kind based on the RGEs in the seesaw-extended standard model, and show its direct link to the CP-violating phases of $U$ at low energies.

   hep-phhep-exJHEP(2020)·23 citations
8. 08*

   Identifying $D_{sJ}^{\ast }(2860)$ as a four resonance states through strong decay analysis

   Keval Gandhi🇮🇳 · Ajay Kumar Rai🇮🇳 · Takayuki Matsuki🇯🇵

   Experimentally observed excited strange charmed mesons $D_{s0}^{\ast }(2317{)}^{\pm }$, $D_{s1}(2460{)}^{\pm }$, $D_{s1}(2536{)}^{\pm }$, $D_{s2}^{\ast }(2573{)}^{\pm }$, $D_{s1}^{\ast }(2700{)}^{\pm }$, $D_{s1}^{\ast }(2860{)}^{\pm }$, $D_{s3}^{\ast }(2860{)}^{\pm }$, and $D_{sJ}(3040{)}^{\pm }$ are identified tentatively according to their spin, parity, and masses. Using the heavy quark effective theory in the leading order approximation, we study their strong decays to ground state charmed mesons plus light pseudoscalar mesons. The branching ratios are classified, $(D_{s0}^{\ast }(2317),D_{s1}(2460))$ as $(1^3{P}_0,1P_1)$ and $(D_{s1}(2536),D_{s2}^{\ast }(2573))$ as $(1P_1^{\prime },1^3{P}_2)$, in heavy quark doublets. The $D_{s1}^{\ast }(2700)$ as $2^3{S}_1$ and its spin partner, $2^1{S}_0$ is still missing in the experiment. Its strong decay behavior is predicted. The assignment of $D_{sJ}^{\ast }(2860)$ as four resonance states $D_{s1}^{\ast }(2860)$, $D_{s2}^{\ast }(2860)$, $D_{s2}^{\ast \prime }(2860)$, $D_{s3}^{\ast }(2860)$ is favored, where for $D_{s3}^{\ast }(2860{)}^{\pm }$ the mass should be expected to higher than 2.86 GeV. The $D_{sJ}(3040)$ is more likely to be 2$P_1$ state. We construct the Regge trajectories of experimentally observed strange charmed mesons in $(M^2,J)$ and $(M^2,n_r)$ planes, which estimate the masses of $1^3{D}_3$, $1^3{F}_4$, $1D_2$, $1^1{F}_3$, $1D_2^{\prime }$, $1F_3^{\prime }$, $3^3{S}_1$, and $3P_1$ states with fixing the slopes and intercepts of the Regge lines. Moreover, the strong decay rates and the branching ratios of these higher excited states are also examined, which distinguished the dominant decay channels for these higher excited states. Our results could provide some important clues in LHCb, BESIII, KEK-B, and the forthcoming Belle II and $\overline{\text{mbox}\text{sffamily}P}${\sffamily ANDA} experiments.

   hep-ph4 citations
9. 09*

   Predictive $S_4$ flavon model with ${\text{TM}}_1$ mixing and baryogenesis through leptogenesis

   Mainak Chakraborty🇮🇳 · R. Krishnan🇮🇳 · Ambar Ghosal🇮🇳

   We use $S_4$ discrete group to construct a neutrino flavour model which leads to $T{M}_1$ mixing and is consistent with the neutrino oscillation data. Using the model's constrained parameter space, we predict the values of Dirac $CP$ phase and the light neutrino mass as $-1<\sin \delta <-0.9$ and $1.7<m_1(\text{meV})<5.5$ respectively. We thoroughly examine the usefulness of this model in explaining the observed baryon asymmetry of the Universe. Near-maximal breaking of CP symmetry (arising due to the ${\text{TM}}_1$ constraint) helps us in generating adequate baryon asymmetry through leptogenesis. We study the evolution of the asymmetry (generated due to the decay of the heavy Majorana neutrinos) starting from the primordial Universe in two different ways (i)explicitly solving network of Boltzmann equations, (ii) using approximate analytic solution and we have shown the extent of their equivalence. Nearly accurate analytical fits are used thereafter to evaluate baryon asymmetry for the whole parameter space allowed by $3\sigma$ global fit of oscillation data and to impose a constraint on the yet unbounded mass scale parameter of Dirac neutrino mass matrix. Furthermore, significant contribution of $N_2$ decay in the context of flavoured leptogenesis is also estimated.

   hep-phJHEP(2020)·17 citations
10. 10*

    Novel Interpretation Strategy for Searches of Singly Produced Vector-like Quarks at the LHC

    Avik Roy🇺🇸 · Nikiforos Nikiforou🇺🇸 · Nuno Castro🇵🇹 · Timothy Andeen🇺🇸

    Vector-like Quarks (VLQs) are potential signatures of physics beyond the Standard Model at the TeV energy scale and major efforts have been put forward at both ATLAS and CMS experiments in search of these particles. In order to make these search results more relatable in the context of most plausible theories of VLQs, it is deemed important to present the analysis results in a general fashion. We investigate the challenges associated with such interpretations of singly produced VLQ searches and propose a generalized, semi-analytical framework that allows a model-independent casting of the results in terms of unconstrained, free parameters of the VLQ Lagrangian. We also propose a simple parameterization of the correction factor to the single VLQ production cross-section at large decay widths. We illustrate how the proposed framework can be used to conveniently represent statistical limits by numerically reinterpreting results from benchmark ATLAS and CMS analyses.

    hep-phhep-exPRD(2020)·52 citations
11. 11*

    Renormalization group evolution induced leptogenesis in the minimal seesaw model with the trimaximal mixing and mu-tau reflection symmetry

    Zhen-hua Zhao🇨🇳

    In this paper, we consider the imbedding of the popular and well-motivated trimaximal mixing and $\mu$-$\tau$ reflection symmetry (which can help us shape the forms of the neutrino mass matrix) in the minimal seesaw model (which contains much fewer parameters than the general seesaw model) with two TeV-scale right-handed neutrinos (for realizing a low-scale seesaw) of nearly degenerate masses (for realizing a resonant leptogenesis). However, either for the trimaximal mixing scenario (which is realized through the Form Dominance approach here) or for the $\mu$-$\tau$ reflection symmetry scenario, leptogenesis cannot proceed. To address this issue, we consider the possibility that the special forms of the neutrino mass matrix for the trimaximal mixing and $\mu$-$\tau$ reflection symmetry are slightly broken by the renormalization group evolution effect, thus allowing leptogenesis to proceed. It is found that in the normal case of the neutrino mass ordering, the baryon asymmetry thus generated can reproduce the observed value. For completeness, we have also extended our analysis to the scenario that two right-handed neutrinos are not nearly degenerate any more. Unfortunately, in this scenario the final baryon asymmetry is smaller than the observed value by several orders of magnitude.

    hep-phJHEP(2021)·24 citations
12. 12*

    Sector Showers for Hadron Collisions

    Helen Brooks🇦🇺 · Christian T Preuss🇦🇺 · Peter Skands🇦🇺

    In conventional parton showers (including ones based on dipoles/antennae), a given $(\mathrm{Born}+m)$-parton configuration can typically be reached via $\mathcal{O}(m!)$ different "shower histories". In the context of matrix-element-correction and merging procedures, accounting for these histories mandates fairly complex and resource-intensive algorithms. A so far little-explored alternative in the shower context is to divide the branching phase spaces into distinct "sectors", each of which only receives contributions from a single branching kernel. This has a number of consequences including making the shower operator bijective; i.e., each parton configuration now has a single unique "inverse". As a first step towards developing a full-fledged matrix-element-correction and merging procedure based on such showers, we here extend the sector approach for antenna showers to hadron-hadron collisions, including mass and helicity dependence.

    hep-phhep-exJHEP(2020)·53 citations
13. 13*

    Search for electric dipole moments

    Klaus Kirch🇨🇭 · Philipp Schmidt-Wellenburg🇨🇭

    Searches for permanent electric dipole moments of fundamental particles and systems with spin are the experiments most sensitive to new CP violating physics and a top priority of a growing international community. We briefly review the current status of the field emphasizing on the charged leptons and lightest baryons.

    hep-phhep-exEPJ Web Conf.(2020)·15 citations
14. 14*

    Chirality transfer & chiral turbulence in gauge theories

    M. Mace🇫🇮 · N. Mueller🇺🇸 · S. Schlichting🇩🇪 · S. Sharma🇮🇳

    Chirality transfer between fermions and gauge fields plays a crucial role for understanding the dynamics of anomalous transport phenomena such as the Chiral Magnetic Effect. In this proceeding we present a first principles study of these processes based on classical-statistical real-time lattice simulations of strongly coupled QED $(e^2{N}_f=64)$. Our simulations demonstrate that a chirality imbalance in the fermion sector triggers chiral plasma instabilities in the gauge field sector, which ultimately lead to the generation of long range helical magnetic fields via a self-similar turbulent cascade of the magnetic helicity.

    hep-phastro-ph.COhep-thNPA(2021)·4 citations
15. 15*

    Constraints on non-Newtonian gravity and axionlike particles from measuring the Casimir force in nanometer separation range

    G. L. Klimchitskaya🇷🇺 · P. Kuusk🇪🇪 · V. M. Mostepanenko🇷🇺

    We obtain constraints on the Yukawa-type corrections to Newton's gravitational law and on the coupling constant of axionlike particles to nucleons following from the experiment on measuring the Casimir force between an Au-coated microsphere and a silicon carbide plate. For this purpose, both the Yukawa-type force and the force due to two-axion exchange between nucleons are calculated in the experimental configuration. In the interaction range of Yukawa force exceeding 1 nm and for axion masses above 17.8 eV, the obtained constraints are much stronger than those found previously from measuring the lateral Casimir force between sinusoidally corrugated surfaces. These results are compared with the results of other laboratory experiments on constraining non-Newtonian gravity and axionlike particles in the relevant interaction ranges.

    hep-phPRD(2020)·27 citations
16. 16*

    Dipole Subtraction vs. Phase Space Slicing in NLO NRQCD Heavy-Quarkonium Production Calculations

    Mathias Butenschoen🇩🇪 · Bernd A. Kniehl🇩🇪

    We compare two approaches to evaluate cross sections of heavy-quarkonium production at next-to-leading order in nonrelativistic QCD involving $S$- and $P$-wave Fock states: the customary approach based on phase space slicing and the approach based on dipole subtraction recently elaborated by us. We find reasonable agreement between the numerical results of the two implementations, but the dipole subtraction implementation outperforms the phase space slicing one both with regard to accuracy and speed.

    hep-phNPB(2020)·10 citations
17. 17*

    Electric charge quantization in 331 Models with exotic charges

    David Romero Abad🇵🇪 · Jose Reyes Portales🇵🇪 · Elmer Ramirez Barreto🇵🇪

    The extensions of the Standard Model based on the $SU(3{)}_C\otimes SU(3{)}_L\otimes U(1{)}_X$ gauge group are known as 331 Models. Different properties such as the fermion assignment and the electric charges of the exotic spectrum, that defines a particular 331 model, are fixed by a $\beta$ parameter. In this article we study the electric charge quantization in two versions of the 331 models, set by the conditions $\beta =1/\left(3\sqrt{3}\right)$ and $\beta =0$. In these frameworks, arise exotic particles, for instance, new leptons and gauge bosons with a fractional electric charge. Additionally, depending on the version, quarks with non-standard fractional electric charges or even neutral appear. Considering the definition of electric charge operator as a linear combination of the group generators that annihilates the vacuum, classical constraints from the invariance of the lagrangian, and gauge and mixed gauge-gravitational anomalies cancellation, the quantization of the electric charge can be verified in both versions.

    hep-phhep-thPramana(2020)·2 citations
18. 18*

    The landscape of QCD axion models

    Luca Di Luzio🇩🇪 · Maurizio Giannotti🇺🇸 · Enrico Nardi🇮🇹 · Luca Visinelli🇳🇱

    We review the landscape of QCD axion models. Theoretical constructions that extend the window for the axion mass and couplings beyond conventional regions are highlighted and classified. Bounds from cosmology, astrophysics and experimental searches are reexamined and updated.

    hep-phastro-ph.COastro-ph.SRhep-ex+1Phys.Rept.(2020)·1186 citations
19. 19*

    Fingerprinting the contribution of colored scalars to the $H^{+}{W}^{-}Z(\gamma )$ vertex

    Nabarun Chakrabarty🇮🇳 · Indrani Chakraborty🇮🇳 · Dilip Kumar Ghosh🇮🇳

    Color-octet scalars arise in various Grand Unification scenarios and also in other models of new physics. They are also postulated for minimal flavour violation. Purely phenomenological imprints of such scalars are therefore worth looking at. Motivated by this, we perform a complete one-loop calculation of the $H^{+}\to W^{+}Z(\text{g})$ decay in a two Higgs doublet model augmented by a color-octet $SU(2{)}_L$ scalar doublet. The computation is conveniently segregated into colorless and colored components. The color-octet part of the amplitude, being scaled by the color-factor, provides an overall enhancement to the form factors. Crucial constraints from perturbative unitarity, positivity of the scalar potential, oblique parameters, Higgs signal strengths and direct search of a charged Higgs and color-octet scalars are folded-in into the analysis. Sensitivity of the loop-induced $H^{+}\to W^{+}Z(\text{g})$ vertex to other model parameters is elucidated. Finally, the prospect of observing a loop-induced $H^{+}\to W^{+}Z(\text{g})$ interaction at the future hadronic collisions is also discussed.

    hep-phEPJC(2020)·7 citations
20. 20*

    First extraction of the $\Lambda$ polarising fragmentation function from Belle $e^{+}{e}^{-}$ data

    Umberto D'Alesio🇮🇹 · Francesco Murgia🇮🇹 · Marco Zaccheddu🇮🇹

    We present a thorough phenomenological analysis of the experimental data from Belle Collaboration for the transverse $\Lambda$ and $\bar{\Lambda }$ polarisation, measured in $e^{+}{e}^{-}$ annihilation processes, for the case of inclusive (plus a jet) and associated production with a light charged hadron. This allows for the first ever extraction of the quark polarising fragmentation function for a $\Lambda$ hyperon, a transverse momentum dependent distribution giving the probability that an unpolarised quark fragments into a transversely polarised spin-1/2 hadron.

    hep-phPRD(2020)·61 citations
21. 21*

    $\Delta (27)$ framework for cobimaximal neutrino mixing models

    A. E. Cárcamo Hernández🇨🇱 · Ivo de Medeiros Varzielas🇵🇹

    We propose a simple framework based on $\Delta (27)$ that leads to the successful cobimaximal lepton mixing ansatz, thus providing a predictive explanation for leptonic mixing observables. We explore first the effective neutrino mass operators, then present a specific model realization based on type I seesaw, and also propose a model with radiative 1-loop seesaw which features viable dark matter candidates.

    hep-phPLB(2020)·25 citations
22. 22*

    Highly polarised gamma photons from electron-laser collisions

    S. Tang🇬🇧 · B. King🇬🇧 · H. Hu🇨🇳

    We detail a method to produce a GeV-photon source with polarisation purity exceeding $96\%$ and $89\%$ for linear and circular polarisation respectively and with a brilliance of the order of $10^{21}\text{photons}/(\text{s}{\text{mm}}^2{\text{mrad}}^{2}0.1\%\text{BW})$. Using currently available multi-GeV electron bunches and laser pulses of moderately relativistic intensities, we show how the weakly nonlinear regime can produce photons polarised mainly parallel to the laser field. We demonstrate the robustness of this scheme by considering electron bunches of various emissivities colliding with linearly and circularly-polarised laser pulses at a range of angles.

    hep-phphysics.opticsPLB(2020)·38 citations
23. 23*

    Data based two-body current contribution to neutrino-nucleus cross section

    Tomasz Bonus🇵🇱 · Jan T. Sobczyk🇵🇱 · Michał Siemaszko🇵🇱 · Cezary Juszczak🇵🇱

    A phenomenological model of two-body current (2p2h) contribution to neutrino cross section is introduced. Predictions of the Valencia model for 2p2h are modified using recent CC0pi measurements from T2K and MINERvA experiments. Our results suggest a significant increase of the 2p2h cross section at neutrino energies bigger than 1 GeV and also a redistribution of 2p2h events as function of energy and momentum transfer. This may have a big impact on neutrino energy reconstruction in neutrino oscillation parameters.

    ↳ hep-exhep-phPRC(2020)·14 citations
24. 24*

    Entering the Era of Dark Matter Astronomy? Near to Long-Term Forecasts in X-Ray and Gamma-Ray Bands

    Dawei Zhong🇨🇳 · Mauro Valli🇺🇸 · Kevork N. Abazajian🇺🇸

    We assess Galactic Dark Matter (DM) sensitivities to photons from annihilation and decay using the spatial and kinematic information determined by state-of-the-art simulations in the Latte suite of Feedback In Realistic Environments (FIRE-2). For kinematic information, we study the energy shift pattern of DM narrow emission lines predicted in FIRE-2 and discuss its potential as DM-signal diagnosis, showing for the first time the power of symmetric observations around $l=0^{\circ }$. We find that the exposures needed to resolve the line separation of DM to gas by XRISM at $5\sigma$ to be large, $\gtrsim 4$ Ms, while exposures are smaller for Athena ($\lesssim 50$ ks) and Lynx ($\lesssim 100$ ks). We find that large field-of-view exposures remain the most sensitive methods for detection of DM annihilation or decay by the luminosity of signals in the field of view dominating velocity information. The $\sim$4 sr view of the Galactic Center region by the Wide Field Monitor (WFM) aboard the eXTP mission will be highly sensitive to DM signals, with a prospect of $\sim 10^5$ to $10^6$ events from the 3.5 keV line in a 100 ks exposure, with the range dependent on photon acceptance in WFM's field of view. We also investigate detailed all-sky luminosity maps for both DM annihilation and decay signals - evaluating the signal-to-noise for a DM detection with realistic X-ray and gamma-ray backgrounds - as a guideline for what could be a forthcoming era of DM astronomy.

    ↳ astro-ph.HEhep-phPRD(2020)·21 citations
25. 25*

    From Quantum Foundations of Quantum Field Theory, String Theory and Quantum Gravity to Dark Matter and Dark Energy

    Djordje Minic🇺🇸

    We review our recent work on quantum foundations of quantum mechanics, quantum field theory and quantum gravity (formulated as metastring theory) and various implications for the problems of dark matter and dark energy. The first point concerns the new understanding of quantum theory via the concept of quantum (modular) spacetime endowed with manifest non-locality that is consistent with causality. This view implies the consistency of the fundamental length and Lorentz symmetry, based on the principle of relative (observer dependent) locality. The geometry of such quantum spacetime is encoded in the new concept of Born geometry. This in turn leads to a novel understanding of quantum field theory in a manifestly bi-local representation endowed with metaparticle quanta. A fully dynamical quantum spacetime, with a dynamical Born geometry, leads to quantum gravity (a quantum theory of dynamical geometry of quantum non-locality) in the guise of metastring theory. This generic formulation of string theory implies a radiatively stable positive cosmological constant (viewed as a curvature of the dual spacetime) as a model of dark energy in the observed classical spacetime, as well as metaparticle quanta (the zero modes of the metastring) as the natural quanta of dark matter in this approach.

    ↳ hep-thgr-qchep-ph15 citations
26. 26*

    Are latest detected events of gravitational waves in favor of some models of inflation based on string theory?

    Basem Ghayour🇮🇳 · Jafar Khodagholizadeh🇮🇷 · M. Afkani🇮🇷 · M. R. Torkamani🇮🇷 · Ali Vahedi🇮🇷

    The general potential of power-law inflation is as $V(\varphi )\propto {\varphi }^n$ with scalar field $\varphi$. The behavior of inflation is often known as power-law expansion like $S(\eta )\propto {\eta }^{1+\beta }$ with $1+\beta <0$. In this paper, the theoretical spectra of relic gravitational waves are compared with the measured strain sensitivity of Advanced LIGO and VIRGO, corresponding to the latest detected events of gravitational waves. The results show tight constraints on $\beta$ and $n$. Also, the obtained constraints indicate that special types of the potential of inflation, prototype, and KKLTI models, which are originated from string theory, are more suitable than other models. Our analysis shows that there exist some more chances for the detection of relic gravitational waves.

    ↳ astro-ph.COhep-phhep-thInt.J.Mod.Phys.D(2021)·2 citations
27. 27*

    $B_c\to B_{s(d)}$ form factors from lattice QCD

    Laurence J. Cooper🇬🇧 · Christine T. H. Davies🇬🇧 · Judd Harrison🇬🇧 · Javad Komijani🇬🇧 · Matthew Wingate🇬🇧

    We present results of the first lattice QCD calculations of $B_c\to B_s$ and $B_c\to B_d$ weak matrix elements. Form factors across the entire physical $q^2$ range are then extracted and extrapolated to the physical-continuum limit before combining with CKM matrix elements to predict the semileptonic decay rates $\Gamma (B_c^{+}\to B_s^0\overline{\ell }{\nu }_{\ell })=26.2(1.2)\times 10^9{\text{s}}^{-1}$ and $\Gamma (B_c^{+}\to B^0\overline{\ell }{\nu }_{\ell })=1.65(10)\times 10^9{\text{s}}^{-1}$. The lattice QCD uncertainty is comparable to the CKM uncertainty here. Results are derived from correlation functions computed on MILC Collaboration gauge configurations with a range of lattice spacings including 2+1+1 flavours of dynamical sea quarks in the Highly Improved Staggered Quark (HISQ) formalism. HISQ is also used for the propagators of the valence light, strange, and charm quarks. Two different formalisms are employed for the bottom quark: non-relativistic QCD (NRQCD) and heavy-HISQ. Checking agreement between these two approaches is an important test of our strategies for heavy quarks on the lattice. From chained fits of NRQCD and heavy-HISQ data, we obtain the differential decay rates $d\Gamma /d{q}^2$ as well as integrated values for comparison to future experimental results.

    ↳ hep-lathep-phPRD(2020)·42 citations
28. 28*

    On dimension of tetrads in effective gravity

    G.E. Volovik🇫🇮

    Two different sources of emergent gravity lead to the inverse square of length dimension of metric field, $[g_{\mu \nu }]=1/[l{]}^2$, as distinct from the conventional dimensionless metric, $[g_{\mu \nu }]=1$, for $c=1$. In both scenarios all the physical quantities, which obey diffeomorphism invariance, such as the Newton constant, the scalar curvature, the cosmological constant, particle masses, fermionic and scalar bosonic fields, etc., are dimensionless.

    ↳ gr-qccond-mat.otherhep-phJETP Lett.(2020)·3 citations
29. 29*

    Constraints on charm-anticharm asymmetry in the nucleon from lattice QCD

    Raza Sabbir Sufian🇺🇸 · Tianbo Liu🇺🇸 · Andrei Alexandru🇺🇸 · Stanley J. Brodsky🇺🇸 · Guy F. de Téramond🇨🇷 · Hans Günter Dosch🇩🇪 · Terrence Draper🇺🇸 · Keh-Fei Liu🇺🇸 · Yi-Bo Yang🇨🇳

    We present the first lattice QCD calculation of the charm quark contribution to the nucleon electromagnetic form factors $G_{E,M}^c(Q^2)$ in the momentum transfer range $0\le Q^2\le 1.4$ $\mathrm{Ge}{\mathrm{V}}^2$. The quark mass dependence, finite lattice spacing and volume corrections are taken into account simultaneously based on the calculation on three gauge ensembles including one at the physical pion mass. The nonzero value of the charm magnetic moment ${\mu }_M^c=-0.00127(38{)}_{\mathrm{stat}}(5{)}_{\mathrm{sys}}$, as well as the Pauli form factor, reflects a nontrivial role of the charm sea in the nucleon spin structure. The nonzero $G_E^c(Q^2)$ indicates the existence of a nonvanishing asymmetric charm-anticharm sea in the nucleon. Performing a nonperturbative analysis based on holographic QCD and the generalized Veneziano model, we study the constraints on the $[c(x)-\bar{c}(x)]$ distribution from the lattice QCD results presented here. Our results provide complementary information and motivation for more detailed studies of physical observables that are sensitive to intrinsic charm and for future global analyses of parton distributions including asymmetric charm-anticharm distribution.

    ↳ hep-lathep-exhep-phnucl-thPLB(2020)·52 citations
30. 30*

    Towards a general parametrization of the warm dark matter halo mass function

    Mark R. Lovell (University of Iceland)🇮🇸

    Studies of flux anomalies statistics and perturbations in stellar streams have the potential to constrain models of warm dark matter (WDM), including sterile neutrinos. Producing these constraints requires a parametrization of the WDM mass function relative to that of the cold dark matter (CDM) equivalent. We use five WDM models with half-mode masses, $M_{\mathrm{hm}}=[1.3,35]\times 10^8$~$M_{\odot }$, spread across simulations of the Local Group, lensing ellipticals and the $z=2$ universe, to generate such a parametrization: we fit parameters to a functional form for the WDM-to-CDM halo mass function ratio, $n_{\mathrm{WDM}}(M_X)/n_{\mathrm{CDM}}(M_X)$, of ($1+(\alpha M_{\mathrm{hm}}/M_X{)}^{\beta }{)}^{\gamma }$. For $M_X\equiv$ virial mass of central halos we obtain $\alpha =2.3$, $\beta =0.8$, and $\gamma =-1.0$, and this fit is steeper than the extended Press-Schechter formalism predicts. For $M_X\equiv$ mass of subhalos we instead obtain $\alpha =4.2$, $\beta =2.5$ and $\gamma =-0.2$; in both mass definitions the scatter is $\sim 20$~per~cent. The second fit typically underestimates the relative abundance of $z=2$ WDM subhaloes at the tens of per cent level. We caution that robust constraints will require bespoke simulations and a careful definition of halo mass, particularly for subhalos of mass $<10^8{M}_{\odot }$.

    ↳ astro-ph.COastro-ph.GAhep-phApJ(2020)·43 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.