Wed·Oct 16, 2019Wednesday·October 16, 2019

1. 01*

   Implications of the Gaia Sausage for Dark Matter Nuclear Interactions

   Jatan Buch🇺🇸 · JiJi Fan🇺🇸 · John Shing Chau Leung🇺🇸

   The advent of the Gaia era has led to potentially revolutionary understanding of dark matter (DM) dynamics in our galaxy, which has important consequences for direct detection (DD) experiments. In this paper, we study how the empirical DM velocity distribution inferred from Gaia-Sausage, a dominant substructure in the solar neighborhood, affects the interpretation of DD data. We survey different classes of operators in the non-relativistic effective field theory that could arise from several relativistic benchmark models and emphasize that the Gaia velocity distribution could modify both the total number of events as well as the shape of the differential recoil spectra, the two primary observables in DD experiments. Employing the euclideanized signal method, we investigate the effects of the Gaia distribution on reconstructing DM model parameters and identifying the correct DM model given a positive signal at future DD experiments. We find that for light DM with mass ~10 GeV, the Gaia distribution poses an additional challenge for characterizing DM interactions with ordinary matter, which may be addressed by combining complementary DD experiments with different targets and lowering the detection threshold. Meanwhile, for heavy DM with mass above ~30 GeV, depending on the type of DM model, there could be a (moderate) improvement in the sensitivity at future DD experiments.

   hep-phastro-ph.COastro-ph.GAPRD(2020)·26 citations
2. 02*

   The charged $Z_c$ and $Z_b$ structures in a constituent quark model approach

   Pablo G. Ortega🇪🇸 · Jorge Segovia🇪🇸 · David R. Entem🇪🇸 · Francisco Fernández🇪🇸

   The nature of the recently discovered $Z_c$ and $Z_b$ structures is intriguing. Their charge forces its minimal quark content to be $Q\bar{Q}q\bar{q}$ (where $Q=\{c,b\}$ and $q=\{u,d\}$). In this work we perform a molecular coupled-channels calculation of the $I^G(J^{PC})=1^{+}(1^{+-})$ charm and bottom sectors in the framework of a constituent quark model which satisfactorily describes a wide range of properties of (non-)conventional hadrons containing heavy quarks. All the relevant channels are included for each sector, i.e.: The $D^{(\ast )}{\bar{D}}^{\ast }+h.c.$, $\pi J/\psi$ and $\rho {\eta }_c$ channels for the $Z_c$ and $B^{(\ast )}{B}^{\ast }$ and ${\rm Y}(nS)\pi$ ($n=1,2,3$) channels for the $Z_b$ analysis. Possible structures of these resonances will be discussed.

   hep-phSciPost Phys.Proc.(2020)·3 citations
3. 03*

   Relativistic calculations of $R(D^{(\ast )})$, $R(D_s^{(\ast )})$, $R({\eta }_c)$ and $R(J/\psi )$

   Tian Zhou🇨🇳 · Tian-hong Wang🇨🇳 · Yue Jiang🇨🇳 · Xiao-Ze Tan🇨🇳 · Geng Li🇨🇳 · Guo-Li Wang🇨🇳

   Recently, the deviation of the ratios $R(D)$, $R(D^{\ast })$ and $R(J/\psi )$ have been found between experimental data and the Standard Model predictions, which may be the hint of New Physics. In this work, we calculate these ratios within the Standard Model by using the improved instantaneous Bethe-Salpeter method. The emphasis is pad to the relativistic correction of the form factors. The results are $R(D)=0.312_{-0.007}^{+0.006}$, $R(D^{\ast })=0.249_{-0.002}^{+0.001}$, $R(D_s)=0.320_{-0.009}^{+0.009}$, $R(D_s^{\ast })=0.251_{-0.003}^{+0.002}$, $R({\eta }_c)=0.384_{-0.042}^{+0.032}$, and $R(J/\psi )=0.267_{-0.011}^{+0.009}$, which are consistent with predictions of other models and the experimental data. The semileptonic decay rates and corresponding form factors at zero recoil are also given.

   hep-phInt.J.Mod.Phys.A(2020)·13 citations
4. 04*

   Chemical equilibration of QGP in hadronic collisions

   Aleksi Kurkela🇨🇭 · Aleksas Mazeliauskas🇨🇭

   We performed state-of-the-art QCD effective kinetic theory simulations of chemically equilibrating QGP in longitudinally expanding systems. We find that chemical equilibration takes place after hydrodynamization, but well before local thermalization. By relating the transport properties of QGP and the system size we estimate that hadronic collisions with final state multiplicities $d{N}_{\text{ch}}/d\eta >10^2$ live long enough to reach approximate chemical equilibrium for all collision systems. Therefore we expect the saturation of strangeness enhancement to occur at the same multiplicity in proton-proton, proton-nucleus and nucleus-nucleus collisions.

   hep-phnucl-exnucl-thSpringer Proc.Phys.(2020)·2 citations
5. 05*

   Central exclusive diffractive production of two-pion continuum at hadron colliders

   R.A. Ryutin🇷🇺

   Calculations of central exclusive diffractive di-pion continuum production are presented in the Regge-eikonal approach. Data from ISR, STAR, CDF and CMS were analyzed and compared with theoretical description. We also consider theoretical predictions for LHC, possible nuances and problems of calculations and prospects of investigations at present and future hadron colliders.

   hep-phEPJC(2019)·7 citations
6. 06*

   Four-particle scattering amplitudes in QCD at NNLO to higher orders in the dimensional regulator

   Taushif Ahmed🇩🇪 · Johannes Henn🇩🇪 · Bernhard Mistlberger🇺🇸

   We compute all helicity amplitudes for four-particle scattering in massless QCD with $n_f$ fermion flavours to next-to-next-to-leading order (NNLO) in perturbation theory. In particular, we consider all possible configurations of external quarks and gluons. We evaluate the amplitudes in terms of a Laurent series in the dimensional regulator to the order required for future next-to-next-to-next-to-leading order (N${}^3$LO) calculations. The coefficients of the Laurent series are given in terms of harmonic polylogarithms that can readily be evaluated numerically. We present our findings in the conventional dimensional regularisation and in the t'Hooft-Veltman schemes.

   hep-phhep-thJHEP(2019)·30 citations
7. 07*

   ${\theta }_{23}=\pi /4$ and $\delta =-\pi /2$ In Neutrino Mixing, Which Convention?

   Junxing Pan🇨🇳 · Jin Sun🇨🇳 · Xiao-Gang He🇹🇼

   Considerable information has been obtained about neutrino mixing matrix. Present data show that in the particle data group (PDG) parameterization, the 2-3 mixing angle and the CP violating phase are consistent with ${\theta }_{23}=\pi /4$ and ${\delta }_{PDG}=-\pi /2$, respectively. A lot of efforts have been devoted to constructing models in realizing a mixing matrix with these values. However, the particular angles and phase are parameterization convention dependent. The meaning about the specific values for mixing angle and phase needs to be clarified. Using the well known 9 independent ways of parameterizing the mixing matrix, we show in detail how the mixing angles and phase change with conventions even with the 2-3 mixing angle to be $\pi /4$ and the CP violating phase to be $-\pi /2$. The original Kaobayashi-Maskawa and an additional one belong to such a category. The other 6 parameterizations have mixing angles and phase very different values from those in the PDG parameterization although the physical effects are the same. Therefore one should give the specific parameterization convention when making statements about values for mixing angles and phase.

   hep-phhep-exInt.J.Mod.Phys.A(2020)·7 citations
8. 08*

   Constraints on anomalous couplings of the Higgs boson from pair production searches

   Petr Mandrik🇷🇺

   The study of the anomalous non-resonant $HH$ production is presented from the point of view of effective field theory (EFT) parameterization. The searches for $pp\to HH\to \gamma \gamma WW$, $pp\to HH\to \gamma \gamma bb$ and $pp\to HH\to bbbb$ processes by ATLAS experiment at the Large Hadron Collider (LHC) are reproduced. The selection efficiencies and exclusion limits on the $HH$ production cross sections for different Beyond Standard Model (BSM) EFT benchmark models are obtained using the fast Monte-Carlo simulation of the ATLAS detector.

   hep-phhep-exEPJ Web Conf.(2019)·1 citation
9. 09*

   Studying the gluon TMDs with $J/\psi$- and ${\rm Y}$-pair production at the LHC

   Florent Scarpa🇳🇱 · Daniël Boer🇳🇱 · Miguel G. Echevarria🇮🇹 · Jean-Philippe Lansberg🇫🇷 · Cristian Pisano🇮🇹 · Marc Schlegel🇺🇸

   We report on how $J/\psi$- and ${\rm Y}$-pair production are promising processes to access the polarised and unpolarised gluon TMDs at the LHC. We present the formalism used, as well as resulting observables that could be extracted from data.

   hep-phhep-exPoS(2019)·2 citations
10. 10*

    Radiative decays in charmonium beyond the p/m approximation

    R. Bruschini🇪🇸 · P. González🇪🇸

    We analyze the theoretical description of radiative decays in charmonium. We use an elementary emission decay model to build the most general electromagnetic transition operator. We show that accurate results for the widths can be obtained from a simple quark potential model reasonably fitting the spectroscopy if the complete form of the operator is used instead of its standard p/m approximation and the experimental masses are properly implemented in the calculation.

    hep-phPRD(2020)·10 citations
11. 11*

    Re-examination of the rare decay $B_s\to \varphi {\mu }^{+}{\mu }^{-}$ using holographic light-front QCD

    Mohammad Ahmady🇨🇦 · Spencer Keller🇨🇦 · Michael Thibodeau🇨🇦 · Ruben Sandapen🇨🇦

    We calculate the Standard Model (SM) predictions for the differential branching ratio of the rare $B_s\to \varphi {\mu }^{+}{\mu }^{-}$ decays using $B_s\to \varphi$ transition form factors (TFFs) obtained using holographic light-front QCD (hQCD) instead of the traditional QCD sum rules (QCDSR) . Our predictions for the differential branching ratio is in better agreement with the LHCb data. Also, we find that the hQCD prediction for $R_{K^{\ast }\varphi }$, the ratio of the branching fraction of $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ to that of $B_s\to \varphi {\mu }^{+}{\mu }^{-}$ , is in excellent agreement with both the LHCb and CDF results in low $q^2$ range.

    hep-phPRD(2019)·11 citations
12. 12*

    A non-perturbative approach to the study of confinement-deconfinement phase transition in S U(3) dual QCD formulation

    Garima Punetha🇮🇳 · H.C. Chandola🇮🇳

    We provide an analytical derivation of the confinement deconfinement phase transition to QCD in the pure gluon sector at finite temperature within the framework of S U(3) dual QCD formulation. The mechanism of color confinement has been explained by adopting magnetic symmetry to extract magnetic monopoles in a gauge invariant way and produce magnetic condensation of S U(3) dual QCD vacuum which guarantees the dual Meissner effect. The deconfinement phase transition has been described by constructing the effective potential at finite temperature in the imaginary time formalism. The magnetic monopole condensate acts as an order parameter for both the confinement deconfinement phase and has been observed to be associated with the appearance/disappearance of magnetic monopole condensate. The evidence of the confinement deconfinement phase transition is further confirmed by the appearance/disappearance of the dual Meissner effect and the existence/breaking of flux tube with temperature. The gauge-invariant vector and scalar glueball masses at finite temperature have been obtained from the minimization of the effective potential at finite temperature which seems to demonstrate a first order deconfinement phase transition associated with the restoration of magnetic symmetry.

    hep-ph0 citations
13. 13*

    The "96 GeV excess" in the N2HDM

    T. Biekötter🇩🇪 · M. Chakraborti🇪🇸 · S. Heinemeyer🇪🇸

    The CMS collaboration reported an intriguing $\sim 3\sigma$ (local) excess at $96$GeV in the light Higgs-boson search in the diphoton decay mode. This mass coincides with a $\sim 2\sigma$ (local) excess in the $b\bar{b}$ final state at LEP. We present the interpretation of this possible signal as the lightest Higgs boson in the 2 Higgs Doublet Model with an additional real Higgs singlet (N2HDM). We show that the type II and type IV (flipped) of the N2HDM can perfectly accommodate both excesses simultaneously, while being in agreement with all experimental and theoretical constraints. The excesses are most easily accommodated in the type II N2HDM, which resembles the Yukawa structure of supersymmetric models. We discuss the experimental prospects for constraining our explanation via charged Higgs-boson decays at the LHC or direct production of the $\sim 96$GeV Higgs boson at a future lepton collider like the ILC.

    hep-ph11 citations
14. 14*

    Particle-number distribution in large fluctuations at the tip of branching random walks

    A.H. Mueller🇺🇸 · S. Munier🇫🇷

    We investigate properties of the particle distribution near the tip of one-dimensional branching random walks at large times $t$, focusing on unusual realizations in which the rightmost lead particle is very far ahead of its expected position - but still within a distance smaller than the diffusion radius $\sim \sqrt{t}$. Our approach consists in a study of the generating function $G_{\Delta x}(\lambda )={\sum }_n{\lambda }^n{p}_n(\Delta x)$ for the probabilities $p_n(\Delta x)$ of observing $n$ particles in an interval of given size $\Delta x$ from the lead particle to its left, fixing the position of the latter. This generating function can be expressed with the help of functions solving the Fisher-Kolmogorov-Petrovsky-Piscounov (FKPP) equation with suitable initial conditions. In the infinite-time and large-$\Delta x$ limits, we find that the mean number of particles in the interval grows exponentially with $\Delta x$, and that the generating function obeys a nontrivial scaling law, depending on $\Delta x$ and $\lambda$ through the combined variable $[\Delta x-f(\lambda ){]}^3/\Delta x^2$, where $f(\lambda )\equiv -\ln (1-\lambda )-\ln [-\ln (1-\lambda )]$. From this property, one may conjecture that the growth of the typical particle number with the size of the interval is slower than exponential, but, surprisingly enough, only by a subleading factor at large $\Delta x$. The scaling we argue is consistent with results from a numerical integration of the FKPP equation.

    ↳ cond-mat.stat-mechhep-phPRE(2020)·7 citations
15. 15*

    Continuous renormalization group $\beta$ function from lattice simulations

    Anna Hasenfratz🇺🇸 · Oliver Witzel🇺🇸

    We present a real-space renormalization group transformation with continuous scale change to calculate the continuous renormalization group $\beta$ function in non-perturbative lattice simulations. Our method is motivated by the connection between Wilsonian renormalization group and the gradient flow transformation. It does not rely on the perturbative definition of the renormalized coupling and is also valid at non-perturbative fixed points. Although our method requires an additional extrapolation compared to traditional step scaling calculations, it has several advantages which compensates for this extra step even when applied in the vicinity of the perturbative fixed point. We illustrate our approach by calculating the $\beta$ function of 2-flavor QCD and show that lattice predictions from individual lattice ensembles, even without the required continuum and finite volume extrapolations, can be very close to the result of the full analysis. Thus our method provides a non-perturbative framework and intuitive understanding into the structure of strongly coupled systems, in addition to being complementary to existing lattice determinations.

    ↳ hep-lathep-phPRD(2020)·45 citations
16. 16*

    Exploring the tension between nature and the Standard Model: the muon g-2

    Marina Krstic Marinkovic🇮🇪 · Nuno Cardoso🇵🇹

    Anomalous magnetic moment of the muon (muon g-2) is one of the most precisely measured quantities in particle physics. At the same time, it can be evaluated in the Standard Model with an unprecedented accuracy. The Muon g-2 experiment at Fermilab has started the major data collection and the aimed four-fold increase in precision will shed light on the current discrepancy between the theory prediction and the measured value. This renders a comparable improvement of the precision in the SM theory an essential ingredient in order to fully exploit the expected increase of precision in experimental results. For all these reasons, the muon g-2 is considered to be a great testing ground for new physics. Hadronic contributions are the dominant sources of uncertainty in the theoretical prediction of the muon g-2. A reciprocal effort to a precise determination of the leading hadronic contribution to the muon g-2 using lattice gauge theories is a direct measurement of the hadronic contributions to the running of the fine structure constant recently proposed by the MUonE experiment. A hybrid strategy including both experimental and lattice data sets is expected to give an independent check of the dispersive results from $e^{+}{e}^{-}$ annihilation, which dominate the current world average.

    ↳ hep-lathep-phJ.Phys.Conf.Ser.(2020)·1 citation
17. 17*

    Progress Towards Ramsey Hyperfine Spectroscopy in ASACUSA

    A. Nanda (On behalf of the ASACUSA-CUSP Collaboration)🇦🇹

    This proceedings contribution reports on progress on the design of a Ramsey-type spectrometer that will be used for the spectroscopy of the ground-state hyperfine structure of both hydrogen and deuterium.

    ↳ physics.ins-dethep-exhep-phphysics.atom-ph1 citation
18. 18*

    Differentiable probabilistic programming for strong gravitational lensing

    Marco Chianese🇳🇱

    The difficult task of observing Dark Matter subhaloes is of paramount importance since it would constrain Dark Matter particle properties (cold or warm relic) and confirm once again the longstanding $\Lambda$CDM model. In the near future the new generation of ground and space surveys will observe thousands of strong gravitational lensing systems providing a unique probe of Dark Matter substructures. Here, we describe a new strong lensing analysis pipeline that combines deep Convolutional Neural Networks with physical models and exploits traditional sampling techniques such as Hamiltonian Monte Carlo. Using simulated strong gravitational lensing systems, we discuss first results and characterize the accuracy of the reconstruction of the main lensing parameters.

    ↳ astro-ph.COastro-ph.GAastro-ph.IMhep-phPoS(2020)·1 citation
19. 19*

    Constraining power of open likelihoods, made prior-independent

    S. Gariazzo🇪🇸

    One of the most criticized features of Bayesian statistics is the fact that credible intervals, especially when open likelihoods are involved, may strongly depend on the prior shape and range. Many analyses involving open likelihoods are affected by the eternal dilemma of choosing between linear and logarithmic prior, and in particular in the latter case the situation is worsened by the dependence on the prior range under consideration. In this letter, we revive a simple method to obtain constraints that depend neither on the prior shape nor range and, using the tools of Bayesian model comparison, extend it to overcome the possible dependence of the bounds on the choice of free parameters in the numerical analysis. An application to the case of cosmological bounds on the sum of the neutrino masses is discussed as an example.

    ↳ astro-ph.COhep-phphysics.data-anEPJC(2020)·19 citations
20. 20*

    Frame Covariance in Quantum Gravity

    Kieran Finn🇬🇧 · Sotirios Karamitsos🇬🇧 · Apostolos Pilaftsis🇬🇧

    We develop a quantum effective action for scalar-tensor theories of gravity which is both spacetime diffeomorphism invariant and field reparameterisation (frame) invariant beyond the classical approximation. We achieve this by extending the Vilkovisky-DeWitt formalism, treating both the scalar fields and the components of the gravitational tensor field as coordinates describing a manifold. By using tensors covariant under diffeomorphisms of this manifold, we show that scalar-tensor theories can be written in a form that is manifestly frame invariant at both classical and quantum levels. In~the same context, we show that in order to maintain manifest frame invariance, we must modify the Feynman rules of theories with a non-trivial field space. We show that one such theory is General Relativity by demonstrating explicitly that it has a non-zero field-space Riemann tensor. Thus, when constructing theories of quantum gravity, we must deal not only with curved spacetime, but also with a curved field space. Finally, we address the cosmological frame problem by tracing its origin to the existence of a new model function that appears in the path integral measure. Once this function is fixed, we find that frame transformations have no effect on the quantisation of the theory. The uniqueness of our improved quantum effective action is discussed.

    ↳ hep-thgr-qchep-phPRD(2020)·53 citations
21. 21*

    Spin Polarizations in a Covariant Angular-Momentum-Conserved Chiral Transport Model

    Shuai Y.F. Liu🇺🇸 · Yifeng Sun🇮🇹 · Che Ming Ko🇺🇸

    Using a covariant and angular-momentum-conserved chiral transport model, which takes into account the spin-orbit interactions of chiral fermions in their scatterings via the side jumps, we study the quark spin polarization in quark matter. For a system of rotating and unpolarized massless quarks in an expanding box, we find that side jumps can dynamically polarize the quark spin and result in a final quark spin polarization consistent with that of thermally equilibrated massless quarks in a self-consistent vorticity field. For the quark matter produced in noncentral relativistic heavy ion collisions, we find that in the medium rest frame both the quark local spin polarizations in the direction perpendicular to the reaction plane and along the longitudinal beam direction show an azimuthal angle dependence in the transverse plane similar to those observed in experiments for the Lambda hyperon.

    ↳ nucl-thhep-phnucl-exPRL(2020)·107 citations
22. 22*

    Accessing the axion via compact object binaries

    Michael Kavic🇺🇸 · Steven L. Liebling🇺🇸 · Matthew Lippert🇺🇸 · John H. Simonetti🇺🇸

    Black holes in binaries with other compact objects can provide natural venues for indirect detection of axions or other ultralight fields. The superradiant instability associated with a rapidly spinning black hole leads to the creation of an axion cloud which carries energy and angular momentum from the black hole. This cloud will then decay via gravitational wave emission. We show that the energy lost as a result of this process tends toward an outspiraling of the binary orbit. A given binary system is sensitive to a narrow range of axion masses, determined by the mass of the black hole. Pulsar-black hole binaries, once detected in the electromagnetic band, will allow high-precision measurements of black hole mass loss via timing measurements of the companion pulsar. This avenue of investigation is particularly promising in light of the recent preliminary announcements of two candidate black hole-neutron star mergers by LIGO/VIRGO (#S190814bv and #S190426c). We demonstrate that for such a binary system with a typical millisecond pulsar and a 3-solar-mass black hole, axions with masses between $2.7\times 10^{-12}$ eV and $3.2\times 10^{-12}$ eV are detectable. Recent gravitational wave observations by LIGO/VIRGO of binary black hole mergers imply that, for these binaries, gravitational radiation from the rotating quadrupole moment is a dominant effect, causing an inspiraling orbit. With some reasonable assumptions about the period of the binary when it formed and the spins of the black holes, these observations rule out possible axion masses between $3\times 10^{-13}$ eV and $6\times 10^{-13}$ eV. Future binary black hole observations, for example by LISA, are expected to provide more robust bounds. In some circumstances, neutron stars may also undergo superradiant instabilities, and binary pulsars could be used to exclude axions with certain masses and matter couplings.

    ↳ astro-ph.HEgr-qchep-phhep-thJCAP(2020)·37 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.