Tue·Sep 11, 2018Tuesday·September 11, 2018

1. 01*

   Linear Sigma EFT for Nearly Conformal Gauge Theories

   T. Appelquist🇺🇸 · R. C. Brower🇺🇸 · G. T. Fleming🇺🇸 · A. Gasbarro🇺🇸 · A. Hasenfratz🇺🇸 · J. Ingoldby🇺🇸 · J. Kiskis🇺🇸 · J. C. Osborn🇺🇸 · C. Rebbi🇺🇸 · E. Rinaldi🇺🇸 · D. Schaich🇨🇭 · P. Vranas🇺🇸 · E. Weinberg🇺🇸 · O. Witzel (for the LSD Collaboration)🇺🇸

   We construct a generalized linear sigma model as an effective field theory (EFT) to describe nearly conformal gauge theories at low energies. The work is motivated by recent lattice studies of gauge theories near the conformal window, which have shown that the lightest flavor-singlet scalar state in the spectrum ($\sigma$) can be much lighter than the vector state ($\rho$) and nearly degenerate with the PNGBs ($\pi$) over a large range of quark masses. The EFT incorporates this feature. We highlight the crucial role played by the terms in the potential that explicitly break chiral symmetry. The explicit breaking can be large enough so that a limited set of additional terms in the potential can no longer be neglected, with the EFT still weakly coupled in this new range. The additional terms contribute importantly to the scalar and pion masses. In particular, they relax the inequality $M_{\sigma }^2\ge 3M_{\pi }^2$, allowing for consistency with current lattice data.

   hep-phhep-latPRD(2018)·21 citations
2. 02*

   On the low-energy spectrum of an SU(2) gauge theory with dynamical fermions

   Milan Vujinovic🇦🇹 · Reinhard Alkofer🇦🇹

   The spectrum of light bound states in an SU(2) gauge theory with two flavors of fundamentally charged fermions is investigated by solving the Bethe-Salpeter equations in the respective channels within a 3PI-type (i.e., beyond rainbow-ladder) truncation including self-consistently a correspondingly truncated fermion--gauge-boson vertex. Remarkable differences with respect to the meson spectrum of an SU(3) gauge theory are found although in our approach these are not as pronounced as indicated by some recent respective investigations within lattice gauge field theory.

   hep-phPRD(2018)·7 citations
3. 03*

   Triple Higgs Boson Coupling in Gauge-Higgs Unification

   Yuki Adachi🇯🇵 · Nobuhito Maru🇯🇵

   We consider the triple coupling of the Higgs boson in the context of the gauge-Higgs unification scenario. We show that the triple coupling of the Higgs boson in this scenario generically deviates from SM prediction since the Higgs potential in this scenario has a periodicity. We calculate the coupling in the five-dimensional $SU(3)$ x $U(1{)}_X$ gauge-Higgs unification model and obtain 70% deviation from the SM prediction.

   hep-ph3 citations
4. 04*

   Augmenting the Gauge-Gravity Correspondence to include Hadron Polarizabilities

   Pervez Hoodbhoy🇵🇰

   ADS/CFT models have achieved considerable success in describing hadronic properties such as masses and Regge trajectories. Even if the minimal vertex that couples photons to structureless spin-zero fields is used, one still ends up with electromagnetic form factors of hadrons that are in fair to good agreement with experiment. However, contradicting both experiment and intuition, this minimal model gives zero for hadronic electric and magnetic polarizabilities. We show here that if effective vertices are used, and axial and vector mesons are allowed to propagate as intermediate states, then the static polarizabilities can in principle be computed from ADS/CFT.

   hep-phnucl-thPRD(2018)·0 citations
5. 05*

   Flavor violation in chromo- and electromagnetic dipole moments induced by $Z^{\prime }$ gauge bosons and a brief revisit of the Standard Model

   J. I. Aranda (1)🇲🇽 · D. Espinosa-Gomez (1)🇲🇽 · J. Montano (1)🇲🇽 · B. Quezadas-Vivian (1)🇲🇽 · F. Ramirez-Zavaleta (1)🇲🇽 · E. S. Tututi (1) ((1) Facultad de Ciencias Fisico-Matematicas, Universidad Michoacana de San Nicolas de Hidalgo)🇲🇽

   The electromagnetic dipole moments of the tau lepton and the chromoelectromagnetic dipole moments of the top quark are estimated via flavor-changing neutral currents, mediated by a new neutral massive gauge boson. We predict them in the context of models beyond the Standard Model with extended current sectors, in which simple analytic expressions for the dipole moments are presented. For the different $Z^{\prime }$ gauge boson considered, the best prediction for the magnetic dipole moment of the tau lepton, $|a_{\tau }|$, is of the order of $10^{-8}$, while the highest value for the electric one, $|d_{\tau }|$, corresponds to $10^{-24}$ $e$cm; our main result for the chromomagnetic dipole moment of the top quark, $|{\hat{\mu }}_t|$, is $10^{-6}$, and the value for the chromoelectric one, $|d_t|$, can be as high as $10^{-22}$ $e$cm. We compare our results, revisiting the corresponding Standard Model predictions, in which the chromomagnetic dipole moment of the top quark is carefully evaluated, finding explicit imaginary contributions.

   hep-phPRD(2018)·20 citations
6. 06*

   Fractal structure of hadrons and non-extensive statistics

   Eugenio Megias🇪🇸 · Airton Deppman🇧🇷 · Tobias Frederico🇧🇷 · Debora P. Menezes🇧🇷

   The role played by non-extensive thermodynamics in physical systems has been under intense debate for the last decades. Some possible mechanisms that could give rise to non-extensive statistics have been formulated along the last few years, in particular the existence of a fractal structure in thermodynamic functions for hadronic systems. We investigate the properties of such fractal thermodynamical systems, in particular the fractal scale invariance is discussed in terms of the Callan-Symanzik~equation. Finally, we propose a diagrammatic method for calculations of relevant quantities.

   hep-phcond-mat.stat-mechnucl-thEPJ Web Conf.(2018)·0 citations
7. 07*

   Effect of an absorbing medium on particle oscillations

   Valeriy Nazaruk🇷🇺

   Particle oscillations in absorbing matter are considered. The approach based on the optical potential is shown to be inapplicable in the strong absorption region. Models with Hermitian Hamiltonian are analyzed. They give an increase of the process width in comparison with the model based on the optical potential.

   hep-phnucl-thPRC(2019)·1 citation
8. 08*

   Analytic Computing Methods for Precision Calculations in Quantum Field Theory

   Johannes Blümlein🇩🇪 · Carsten Schneider🇦🇹

   An overview is presented on the current status of main mathematical computation methods for the multi-loop corrections to single scale observables in quantum field theory and the associated mathematical number and function spaces and algebras. At present massless single scale quantities can be calculated analytically in QCD to 4-loop order and single mass and double mass quantities to 3-loop order, while zero scale quantities have been calculated to 5-loop order. The precision requirements of the planned measurements, particularly at the FCC-ee, form important challenges to theory, and will need important extensions of the presently known methods.

   hep-phhep-thmath-phmath.MPInt.J.Mod.Phys.A(2018)·58 citations
9. 09*

   Resonant state $D_0^{\ast }(2400)$ in the quasi-two-body $B$ meson decays

   Wen-Fei Wang🇨🇳

   We study four quasi-two-body decay processes including $D_0^{\ast }(2400)$ as the intermediate state in perturbative QCD (PQCD) approach. The branching fraction predicted in this work for the decay mode $B^{-}\to D_0^{\ast }(2400{)}^0{\pi }^{-}\to D^{+}{\pi }^{-}{\pi }^{-}$ agree with the data from Belle, BaBar and LHCb Collaborations. The PQCD prediction of the branching ratio for the decay ${\bar{B}}^0\to D_0^{\ast +}{K}^{-}\to D^0{\pi }^{+}{K}^{-}$ is consistent with the value given by LHCb. For the decays ${\bar{B}}^0\to D_0^{\ast +}{\pi }^{-}\to D^0{\pi }^{+}{\pi }^{-}$ and $B^{-}\to D_0^{\ast 0}{K}^{-}\to D^{+}{\pi }^{-}{K}^{-}$, the PQCD predicted branch ratios are $2.85_{-0.80}^{+1.23}({\omega }_B{)}_{-0.81}^{+1.05}({\omega }_{D\pi }{)}_{-0.31}^{+0.33}(a_{D\pi }{)}_{-0.05}^{+0.06}({\Gamma }_{D_0^{\ast +}})\times 10^{-4}$ and $4.65_{-1.30}^{+1.89}({\omega }_B{)}_{-1.24}^{+1.51}({\omega }_{D\pi }{)}_{-0.38}^{+0.40}(a_{D\pi }{)}_{-0.18}^{+0.22}({\Gamma }_{D_0^{\ast 0}})\times 10^{-5}$, respectively. We analyze the experimental branching fractions using the ratios $R_{D_0^{\ast 0}}$ and $R_{D_0^{\ast +}}$ which are related to the decays with the neutral and charged $D_0^{\ast }(2400)$, respectively. The available experimental results for the quasi-two-body decays including $D_0^{\ast }(2400)$ are not in agreement with the isospin relation and $SU(3)$ flavor symmetry.

   hep-phPLB(2019)·15 citations
10. 10*

    Relativistic effects in the semileptonic $B_c$ decays to charmonium with the Bethe-Salpeter method

    Zi-Kan Geng🇨🇳 · Tianhong Wang🇨🇳 · Yue Jiang🇨🇳 · Geng Li🇨🇳 · Xiao-Ze Tan🇨🇳 · Guo-Li Wang🇨🇳

    Relativistic effects are important in the rigorous study of heavy quarks. In this paper, we study the relativistic corrections of semileptonic $B_c$ decays to charmonium with the instantaneous Bethe-Salpeter method. Within the Bethe-Salpeter framework, we use two methods to study the relativistic effects. One of them is to expand the transition amplitude in powers of $\vec{q}$ which is the relative momentum between the quark and antiquark, and the other is to expand the amplitude base on the wave functions. In the level of decay width, the results show that, for the transition of $B_c\to {\eta }_c$, the relativistic correction is about $22\%$; for $B_c\to J/\psi$, it is about $19\%$; the relativistic effects of $1P$ final states are about $14\sim 46\%$ larger than those of $1S$ final states; for $2S$ final states, they are about $19\sim 28\%$ larger than those of $1S$ final states; for $3S$ final states, they are about $12\sim 13\%$ larger than those of $2S$ final states; for $2P$ final states, they are about $10\sim 14\%$ larger than those of $1P$ final states; for $3P$ final states, they are about $7\sim 12\%$ larger than those of $2P$ final states. We conclude that the relativistic corrections of the $B_c$ decays to the orbitally or radially excited charmonium (2S, 3S, 1P, 2P, 3P) are quite large.

    hep-phPRD(2019)·27 citations
11. 11*

    Dynamical picture for the exotic XYZ states

    Mikhail A. Ivanov🇷🇺

    We present a dynamical approach for description of the multi-quark states that is based on an effective interaction Lagrangian describing the coupling of hadrons to their constituent quarks. First, we explore the consequences of treating the $X(3872)$ meson as a tetraquark bound state. We calculate the decay widths of the observed channels and conclude that for reasonable values of the size parameter of the $X(3872)$ one finds consistency with the available experimental data. Then we have critically checked the tetraquark picture for the $Z_c(3900)$ state by analyzing its strong decays. We found that $Z_c(3900)$ has a much more stronger coupling to $D{D}^{\ast }$ than to $J/\psi \pi$ that is in discord with experiment. As an alternative we have employed a molecular-type four-quark current to describe the decays of the $Z_c(3900)$ state as the charged particle in the isotriplet. We found that a molecular-type current gives the values of the above decays in accordance with the experimental observation. By using molecular-type four-quark currents for the recently observed resonances $Z_b(10610)$ and $Z_b(10650)$, we have calculated their two-body decay rates into a bottomonium state plus a light meson as well as into B-meson pairs.

    hep-phhep-exEPJ Web Conf.(2018)·4 citations
12. 12*

    Deuterons at LHC: "snowballs in hell" via hydrodynamics and hadronic afterburner

    Dmytro Oliinychenko🇺🇸 · Long-Gang Pang🇺🇸 · Hannah Elfner🇩🇪 · Volker Koch🇺🇸

    The deuteron yield in Pb+Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV is consistent with thermal production at a freeze-out temperature of $T=155$ MeV. The existence of deuterons with binding energy of 2.2 MeV at this temperature was described as "snowballs in hell". We provide a microscopic explanation of this phenomenon, utilizing relativistic hydrodynamics and switching to a hadronic afterburner at the above mentioned temperature of $T=155$ MeV. The measured deuteron $p_T$-spectra and coalescence parameter $B_2(p_T)$ are reproduced without free parameters, only by implementing experimentally known cross-sections of deuteron reactions with hadrons, most importantly $\pi d\leftrightarrow \pi np$.

    hep-phPRC(2019)·135 citations
13. 13*

    Chiral phase transition within the linear sigma model in the Tsallis nonextensive statistics based on density operator

    Masamichi Ishihara🇯🇵

    We studied the chiral phase transition for small $|1-q|$ within the Tsallis nonextensive statistics of the entropic parameter $q$, where the quantity $|1-q|$ is the measure of the deviation from the Boltzmann-Gibbs statistics. We adopted the normalized $q$-expectation value in this study. We applied the free particle approximation and the massless approximation in the calculations of the expectation values. We estimated the critical physical temperature, and obtained the chiral condensate, the sigma mass, and the pion mass, as functions of the physical temperature $T_{\mathrm{ph}}$ for various $q$. We found the following facts. The $q$-dependence of the critical physical temperature is $1/\sqrt{q}$. The chiral condensate at $q$ is smaller than that at $q^{\prime }$ for $q>q^{\prime }$. The $q$-dependence of the pion mass and that of the sigma mass reflect the $q$-dependence of the condensate. The pion mass at $q$ is heavier than that at $q^{\prime }$ for $q>q^{\prime }$. The sigma mass at $q$ is heavier than that at $q^{\prime }$ for $q>q^{\prime }$ at high physical temperature, while the sigma mass at $q$ is lighter than that at $q^{\prime }$ for $q>q^{\prime }$ at low physical temperature. The quantities which are functions of the physical temperature $T_{\mathrm{ph}}$ and the entropic parameter $q$ are described by only the effective physical temperature defined as $\sqrt{q}{T}_{\mathrm{ph}}$ under the approximations.

    hep-phnucl-thIJMPE(2019)·2 citations
14. 14*

    Exploring dark matter, neutrino mass and $R_{K^{(\ast )},\varphi }$ anomalies in $L_{\mu }-L_{\tau }$ model

    Shivaramakrishna Singirala🇮🇳 · Suchismita Sahoo🇮🇳 · Rukmani Mohanta🇮🇳

    We investigate Majorana dark matter in a new variant of $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge extension of Standard Model, where the scalar sector is enriched with an inert doublet and a $(\bar{3},1,1/3)$ scalar leptoquark. We compute the WIMP-nucleon cross section in leptoquark portal and the relic density mediated by inert doublet components, leptoquark and the new $Z^{\prime }$ boson. We constrain the parameter space consistent with Planck limit on relic density, PICO-60 and LUX bounds on spin-dependent direct detection cross section. Furthermore, we constrain the new couplings from the present experimental data on $\mathrm{Br}(\tau \to \mu {\nu }_{\tau }{\bar{\nu }}_{\mu })$, $\mathrm{Br}(B\to X_s\gamma )$, $\mathrm{Br}(B^0\to K^0{\mu }^{+}{\mu }^{-})$, $\mathrm{Br}(B^{+}\to K^{+}{\tau }^{+}{\tau }^{-})$ and $B_s-\overline{B_s}$ mixing, which occur at one-loop level in the presence of $Z^{\prime }$ and leptoquark. Using the allowed parameter space, we estimate the form factor independent $P_{4,5}^{\prime }$ observables and the lepton non-universality parameters $R_K$, $R_{K^{\ast }}$ and $R_{\varphi }$. We also briefly discuss about the neutrino mass generation at one-loop level and the viable parameter region to explain current neutrino oscillation data.

    hep-phPRD(2019)·40 citations
15. 15*

    Near threshold kaon-kaon interaction in the reactions e+ e- --> K+ K- gamma and e+ e- --> K0 K0bar gamma

    L. Lesniak🇵🇱 · F. Sobczuk🇵🇱 · M. Silarski🇵🇱 · F. Morawski🇵🇱

    Strong interactions between pairs of the K+ K- and K0 K0bar mesons can be studied in radiative decays of phi(1020) mesons. We present a theoretical model of the reactions e+ e- --> phi --> K+ K- gamma and e+ e- --> phi --> K0 K0bar gamma. The K+ K- and K0 K0bar effective mass dependence of the differential cross sections is derived. The total cross sections and the branching fractions for the two radiative phi decays are calculated.

    hep-phEPJ Web Conf.(2019)·0 citations
16. 16*

    Examining the neutrino option

    Ilaria Brivio🇩🇰 · Michael Trott🇩🇰

    The neutrino option is a scenario where the electroweak scale, and thereby the Higgs mass, is generated simultaneously with neutrino masses in the seesaw model. This occurs via the leading one loop and tree level diagrams matching the seesaw model onto the Standard Model Effective Field Theory. We advance the study of this scenario by determining one loop corrections to the leading order matching results systematically, performing a detailed numerical analysis of the consistency of this approach with Neutrino data and the Standard Model particle masses, and by examining the embedding of this scenario into a more ultraviolet complete model. We find that the neutrino option remains a viable and intriguing scenario to explain the origin of observed particle masses.

    hep-phJHEP(2019)·30 citations
17. 17*

    Renormalization Group Effects in Dark Matter Interactions

    Fady Bishara🇬🇧 · Joachim Brod🇺🇸 · Benjamin Grinstein🇺🇸 · Jure Zupan🇺🇸

    We present a renormalization-group (RG) analysis of dark matter interactions with the standard model, where dark matter is allowed to be a component of an electroweak multiplet, and has a mass at or below the electroweak scale. We consider, in addition to the gauge interactions, the complete set of effective operators for dark matter interactions with the standard model above the weak scale, up to and including mass dimension six. We calculate the RG evolution of these operators from the high scale Lambda down to the weak scale, and perform the matching to the tower of effective theories below the weak scale. We also summarize the RG evolution below the weak scale and the matching to the nonrelativistic nuclear interactions. We present several numerical examples and show that in certain cases the dark matter - nucleus scattering rate can change by orders of magnitude when the electroweak running is included.

    hep-phJHEP(2020)·47 citations
18. 18*

    Weak Neutral Current Axial Form Factor Using $(\bar{\nu })\nu$-Nucleon Scattering and Lattice QCD Inputs

    Raza Sabbir Sufian🇺🇸 · Keh-Fei Liu🇺🇸 · David G. Richards🇺🇸

    We present a determination of the neutral current weak axial charge $G_A^Z(0)=-0.654(3{)}_{\mathrm{stat}}(5{)}_{\mathrm{sys}}$ using the strange quark axial charge $G_A^s(0)$ calculated with lattice QCD. We then perform a phenomenological analysis, where we combine the strange quark electromagnetic form factor from lattice QCD with (anti)neutrino-nucleon scattering differential cross section from MiniBooNE experiments in a momentum transfer region $0.24\lesssim Q^2\lesssim 0.71$ GeV${}^2$ to determine the neutral current weak axial form factor $G_A^Z(Q^2)$ in the range of $0\lesssim Q^2\le 1$ GeV${}^2$. This yields a phenomenological value of $G_A^Z(0)=-0.687(89{)}_{\mathrm{stat}}(40{)}_{\mathrm{sys}}$. The value of $G_A^Z(0)$ constrained by the lattice QCD calculation of $G_A^s(0)$, when compared to its phenomenological determination, provides a significant improvement in precision and accuracy and can be used to provide a constraint on the fit to $G_A^Z(Q^2)$ for $Q^2>0$. This constrained fit leads to an unambiguous determination of (anti)neutrino-nucleon neutral current elastic scattering differential cross section near $Q^2=0$ and can play an important role in numerically isolating nuclear effects in this region. We show a consistent description of $G_A^Z(Q^2)$ obtained from the (anti)neutrino-nucleon scattering cross section data requires a nonzero contribution of the strange quark electromagnetic form factor. We demonstrate the robustness of our analysis by providing a post-diction of the BNL E734 experimental data.

    hep-phhep-latnucl-exnucl-thJHEP(2020)·17 citations
19. 19*

    keV Neutrino Dark Matter in a Fast Expanding Universe

    Anirban Biswas🇮🇳 · Debasish Borah🇮🇳 · Dibyendu Nanda🇮🇳

    We study the possibility of keV neutrino dark matter in the minimal $U(1{)}_{B-L}$ gauge extension of the standard model where three right handed neutrinos are automatically included due to the requirement of anomaly cancellations. Without considering extra additional particles or symmetries, we consider the lightest right handed neutrino to be in the keV mass range which is kinematically long lived. Due to gauge interactions, such a keV neutrino can be thermally produced in the early Universe followed by decoupling while being relativistic. The final relic abundance of such keV neutrino typically overclose the Universe requiring additional mechanism to bring it under observed limits. We propose a non-standard cosmological history where a scalar field $\varphi$, that redshifts faster than radiation dominates the Universe prior to the radiation dominated era. We show that such a non-standard phase can keep the abundance of thermally generated keV neutrino dark matter within observed relic abundance. We constrain the non-standard phase, $U(1{)}_{B-L}$ parameters from these requirements and also briefly comment upon the observational aspects of such keV neutrino dark matter.

    hep-phastro-ph.COPLB(2018)·24 citations
20. 20*

    Probing top-quark couplings indirectly at Higgs factories

    Gauthier Durieux🇩🇪 · Jiayin Gu🇩🇪 · Eleni Vryonidou🇨🇭 · Cen Zhang🇨🇳

    We perform a global effective-field-theory analysis to assess the combined precision on Higgs couplings, triple gauge-boson couplings, and top-quark couplings, at future circular $e^{+}{e}^{-}$ colliders, with a focus on runs below the $t\bar{t}$ production threshold. Deviations in the top-quark sector entering as one-loop corrections are consistently taken into account in Higgs and diboson processes. We find that future lepton colliders running at center-of-mass energies below the $t\bar{t}$ production threshold can still provide useful information on top-quark couplings, by measuring virtual top-quark effects. With rate and differential measurements, the indirect individual sensitivity achievable is better than at the high-luminosity LHC. However, strong correlations between the extracted top-quark and Higgs couplings are also present and lead to much weaker global constraints on top-quark couplings. This implies that a direct probe of top-quark couplings above the $t\bar{t}$ production threshold is helpful also for the determination of Higgs and triple-gauge-boson couplings. In addition, we find that below the $e^{+}{e}^{-}\to t\bar{t}h$ production threshold, the top-quark Yukawa coupling can be determined by its loop corrections to all Higgs production and decay channels. Degeneracy with the $ggh$ coupling can be resolved, and even a global limit is competitive with the prospects of a linear collider above the threshold. This provides an additional means of determining the top-quark Yukawa coupling indirectly at lepton colliders.

    hep-phhep-exCPC(2018)·58 citations
21. 21*

    Evaluation of particle--anti-particle scaled correlation within effective models

    Andre Garcia🇧🇷 · Volker Koch🇺🇸 · Marcus Benghi Pinto🇧🇷

    Correlations and fluctuations of physical quantities are known to play an important role in phase transitions and critical phenomena. In recent years some experimental attempts were made in the scope of the Beam Energy Scan program to locate a possible critical point in the QCD phase diagram. In this work we use the Nambu--Jona-Lasinio model to investigate the off-diagonal quark susceptibility, which is related to the quark--anti-quark scaled correlation at the mean field level. We show that this correlation has a significant peak near the critical point and, therefore, may be a useful quantity to measure in experiment. We further study the effects of a repulsive vector coupling, which reduces the strength of the scaled correlation near the critical point.

    ↳ nucl-thhep-phnucl-exNPA(2020)·3 citations
22. 22*

    Quantum Out-of-Equilibrium Cosmology

    Sayantan Choudhury🇩🇪 · Arkaprava Mukherjee🇮🇳 · Prashali Chauhan🇮🇳 · Sandipan Bhattacherjee🇮🇳

    In this work, our prime focus is to study the one to one correspondence between the conduction phenomena in electrical wires with impurity and the scattering events responsible for particle production during stochastic inflation and reheating implemented under a closed quantum mechanical system in early universe cosmology. In this connection, we also present a derivation of fourth order corrected version of the Fokker Planck equation and its analytical solution for studying the dynamical features of the particle creation events in the stochastic inflation and reheating stage of the universe. It is explicitly shown from our computation that quantum corrected Fokker Planck equation describe the particle creation phenomena better for Dirac delta type of scatterer. In this connection, we additionally discuss It$\hat{o}$, Stratonovich prescription and the explicit role of finite temperature effective potential for solving the probability distribution profile. Furthermore, we extend our discussion to describe the quantum description of randomness involved in the dynamics. We also present a computation to derive the expression for the measure of the stochastic non-linearity arising in the stochastic inflation and reheating epoch of the universe, often described by Lyapunov Exponent. Apart from that, we quantify the quantum chaos arising in a closed system by a more strong measure, commonly known as Spectral Form Factor using the principles of Random Matrix Theory (RMT). Additionally, we discuss the role of out of time order correlation (OTOC) function to describe quantum chaos in the present non-equilibrium field theoretic setup. Finally, for completeness, we also provide a bound on the measure of quantum chaos arising due to the presence of stochastic non-linear dynamical interactions into the closed quantum system of the early universe in a completely model-independent way.

    ↳ hep-thastro-ph.COcond-mat.stat-mechgr-qc+1EPJC(2019)·31 citations
23. 23*

    $|V_{us}|$ from $K_{\ell 3}$ decay and four-flavor lattice QCD

    A. Bazavov🇺🇸 · C. Bernard🇺🇸 · C. DeTar🇺🇸 · Daping Du🇺🇸 · A. X. El-Khadra🇺🇸 · E. D. Freeland🇺🇸 · E. Gámiz🇪🇸 · Steven Gottlieb🇺🇸 · U. M. Heller🇺🇸 · J. Komijani🇩🇪 · A. S. Kronfeld🇺🇸 · J. Laiho🇺🇸 and 8 other authors

    Using HISQ $N_f=2+1+1$ MILC ensembles with five different values of the lattice spacing, including four ensembles with physical quark masses, we have performed the most precise computation to date of the $K\to \pi \ell \nu$ vector form factor at zero momentum transfer, $f_{+}^{K^0{\pi }^{-}}(0)=0.9696(15{)}_{\text{stat}}(12{)}_{\text{syst}}$. This is the first calculation that includes the dominant finite-volume effects, as calculated in chiral perturbation theory at next-to-leading order. Our result for the form factor provides a direct determination of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{us}|=0.22333(44{)}_{f_{+}(0)}(42{)}_{\text{exp}}$, with a theory error that is, for the first time, at the same level as the experimental error. The uncertainty of the semileptonic determination is now similar to that from leptonic decays and the ratio $f_{K^{+}}/f_{{\pi }^{+}}$, which uses $|V_{ud}|$ as input. Our value of $|V_{us}|$ is in tension at the 2--$2.6\sigma$ level both with the determinations from leptonic decays and with the unitarity of the CKM matrix. In the test of CKM unitarity in the first row, the current limiting factor is the error in $|V_{ud}|$, although a recent determination of the nucleus-independent radiative corrections to superallowed nuclear $\beta$ decays could reduce the $|V_{ud}{|}^2$ uncertainty nearly to that of $|V_{us}{|}^2$. Alternative unitarity tests using only kaon decays, for which improvements in the theory and experimental inputs are likely in the next few years, reveal similar tensions. As part of our analysis, we calculated the correction to $f_{+}^{K\pi }(0)$ due to nonequilibrated topological charge at leading order in chiral perturbation theory, for both the full-QCD and the partially-quenched cases. We also obtain the combination of low-energy constants in the chiral effective Lagrangian $[C_{12}^r+C_{34}^r-(L_5^r{)}^2](M_{\rho })=(2.92\pm 0.31)\cdot 10^{-6}$.

    ↳ hep-lathep-exhep-phPRD(2019)·89 citations
24. 24*

    Cosmological spectrum of two-point correlation function from vacuum fluctuation of Stringy Axion field in De Sitter space: A study of the role of Quantum Entanglement

    Sayantan Choudhury🇩🇪 · Sudhakar Panda🇮🇳

    In this work, we study the impact of quantum entanglement on the two-point correlation function and the associated primordial power spectrum of mean square vacuum fluctuation in a bipartite quantum field theoretic system. The field theory that we consider is the effective theory of axion field arising from Type IIB string theory compactified to four dimensions. We compute the expression for the power spectrum of vacuum fluctuation in three different approaches, namely (1) field operator expansion (FOE) technique with the quantum entangled state, (2) reduced density matrix (RDM) formalism with mixed quantum state and (3) the method of non-entangled state (NES). For massless axion field, in all these three formalism, we reproduce, at the leading order, the exact scale-invariant power spectrum which is well known in the literature. We observe that due to quantum entanglement, the sub-leading terms for these thee formalisms are different. Thus, such correction terms break the degeneracy among the analysis of the FOE, RDM and NES formalisms in the super-horizon limit. On the other hand, for massive axion field, we get a slight deviation from scale invariance and exactly quantify the spectral tilt of the power spectrum in small scales. Apart from that, for massless and massive axion field, we find distinguishable features of the power spectrum for the FOE, RDM, and NES on the large scales, which is the result of quantum entanglement. We also find that such large-scale effects are comparable to or greater than the curvature radius of the de Sitter space. Most importantly, in the near future, if experiments probe for early universe phenomena, one can detect such small quantum effects. In such a scenario, it is possible to test the implications of quantum entanglement in primordial cosmology.

    ↳ hep-thastro-ph.COgr-qchep-ph+1Universe(2020)·24 citations
25. 25*

    Measurement of $P_T$-weighted Sivers asymmetries in leptoproduction of hadrons

    M.G. Alexeev · G.D. Alexeev · A. Amoroso · V. Andrieux · N.V. Anfimov · V. Anosov · A. Antoshkin · K. Augsten · W. Augustyniak · C.D.R. Azevedo · B. Badelek · F. Balestra and 201 other authors

    The transverse spin asymmetries measured in semi-inclusive leptoproduction of hadrons, when weighted with the hadron transverse momentum $P_T$, allow for the extraction of important transverse-momentum-dependent distribution functions. In particular, the weighted Sivers asymmetries provide direct information on the Sivers function, which is a leading-twist distribution that arises from a correlation between the transverse momentum of an unpolarised quark in a transversely polarised nucleon and the spin of the nucleon. Using the high-statistics data collected by the COMPASS Collaboration in 2010 with a transversely polarised proton target, we have evaluated two types of $P_T$-weighted Sivers asymmetries, which are both proportional to the product of the firsttransverse moment of the Sivers function and of the fragmentation function. The results are compared to the standard unweighted Sivers asymmetries and used to extract the first transverse moments of the Sivers distributions for $u$ and $d$ quarks.

    ↳ hep-exhep-phNPB(2019)·27 citations
26. 26*

    Strangeness $S=-2$ baryon-baryon interactions in relativistic chiral effective field theory

    Kai-Wen Li🇨🇳 · Tetsuo Hyodo🇯🇵 · Li-Sheng Geng🇨🇳

    We study the strangeness $S=-2$ baryon-baryon interactions in relativistic chiral effective field theory at leading order. Among the 15 relevant low energy constants, eight of them are determined by fitting to the state of the art lattice QCD data of the HAL QCD Collaboration (with $m_{\pi }=146$ MeV), and the rest are either taken from the study of the $S=-1$ hyperon-nucleon systems, assuming strict SU(3) flavor symmetry, or temporarily set equal to zero. Using the so-obtained low energy constants, we extrapolate the results to the physical point, and show that they are consistent with the available experimental scattering data. Furthermore, we demonstrate that the $\Lambda \Lambda$ and $\Xi N$ phase shifts near the $\Xi N$ threshold are very sensitive to the lattice QCD data fitted, to the pion mass, and to isospin symmetry breaking effects. As a result, any conclusion drawn from lattice QCD data at unphysical pion masses (even close to the physical point) should be taken with caution. Our results at the physical point, similar to the lattice QCD data, show that a resonance/quasi-bound state may appear in the $I=0$ $\Lambda \Lambda$/$\Xi N$ channel.

    ↳ nucl-thhep-lathep-phPRC(2018)·46 citations
27. 27*

    Testing a quintessence model with Yukawa interaction from cosmological observations and N-body simulations

    Rui An🇨🇳 · André A. Costa🇧🇷 · Linfeng Xiao🇨🇳 · Jiajun Zhang🇨🇳 · Bin Wang🇨🇳

    We consider a quintessence model with Yukawa interaction between dark energy and dark matter and constrain this model by employing the recent cosmological data including the updated cosmic microwave background (CMB) measurements from Planck 2015, the weak gravitational lensing measurements from Kilo Degree Survey (KiDS) and redshift-space distortions. We find that an interaction in the dark sector is compatible with observations. The updated Planck data can significantly improve the constraints compared with the previous results from Planck 2013, while the KiDS data has less constraining power than Planck. The Yukawa interaction model is found to be moderately favored by Planck and able to alleviate the discordance between weak lensing measurements and CMB measurements as previously inferred from the standard Lambda cold dark matter model. N-body simulations for Yukawa interaction model is also performed. We find that using the halo density profile is plausible to improve the constraints significantly in the future.

    ↳ astro-ph.COgr-qchep-phhep-thMNRAS(2019)·23 citations
28. 28*

    Finetuned Cancellations and Improbable Theories

    James D. Wells🇺🇸

    It is argued that the $x-y$ cancellation model (XYCM) is a good proxy for discussions of finetuned cancellations in physical theories. XYCM is then analyzed from a statistical perspective, where it is argued that a finetuned point in the parameter space is not abnormal, with any such point being just as probable as any other point. However, landing inside a standardly defined finetuned region (i.e., the full parameter space of finetuned points) has a much lower probability than landing outside the region, and that probability is invariant under assumed ranges of parameters. This proposition requires asserting also that the finetuned target region is a priori established. Therefore, it is surmised that highly finetuned theories are generally expected to be highly improbable. An actionable implication of this moderate naturalness position is that the search for a non-finetuned explanation to supplant an apparently finetuned theory is likely to be a valid pursuit, but not guaranteed to be. A statistical characterization of this moderate position is presented, as well as those of the extreme pro-naturalness and anti-naturalness positions.

    ↳ physics.hist-phhep-phhep-thFound.Phys.(2019)·14 citations
29. 29*

    How perturbative are heavy sea quarks?

    Andreas Athenodorou🇨🇾 · Jacob Finkenrath🇨🇾 · Francesco Knechtli🇩🇪 · Tomasz Korzec🇩🇪 · Björn Leder🇩🇪 · Marina Krstić Marinković🇮🇪 · Rainer Sommer🇩🇪

    Effects of heavy sea quarks on the low energy physics are described by an effective theory where the expansion parameter is the inverse quark mass, 1/$M$. At leading order in 1/$M$ (and neglecting light quark masses) the dependence of any low energy quantity on $M$ is given in terms of the ratio of $\Lambda$ parameters of the effective and the fundamental theory. We define a function describing the scaling with the mass $M$. We find that its perturbative expansion is very reliable for the bottom quark and also seems to work very well at the charm quark mass. The same is then true for the ratios of ${\Lambda }^{(4)}/{\Lambda }^{(5)}$ and ${\Lambda }^{(3)}/{\Lambda }^{(4)}$, which play a major rôle in connecting lattice determinations of ${\alpha }_{MSbar}^{(3)}$ from the three-flavor theory with ${\alpha }_{MSbar}^{(5)}(M_Z)$. Also the charm quark content of the nucleon, relevant for dark matter searches, can be computed accurately from perturbation theory. We investigate a very closely related model, namely QCD with $N_f=2$ heavy quarks. Our non-perturbative information is derived from simulations on the lattice, with masses up to the charm quark mass and lattice spacings down to about 0.023 fm followed by a continuum extrapolation. The non-perturbative mass dependence agrees within rather small errors with the perturbative prediction at masses around the charm quark mass. Surprisingly, from studying solely the massive theory we can make a prediction for the ratio $Q_{0,2}^{1/\sqrt{t_0}}=[\Lambda \sqrt{t_0(0)}{]}_{N_f=2}/[\Lambda \sqrt{t_0}{]}_{N_f=0}$, which refers to the chiral limit in $N_f=2$. Here $t_0$ is the Gradient Flow scale of [1]. The uncertainty for $Q$ is estimated to be 2.5%. For the phenomenologically interesting ${\Lambda }^{(3)}/{\Lambda }^{(4)}$, we conclude that perturbation theory introduces errors which are at most at the 1.5% level, far smaller than other current uncertainties.

    ↳ hep-lathep-phNPB(2019)·35 citations
30. 30*

    Scaling in necklaces of monopoles and semipoles

    Mark Hindmarsh🇫🇮 · Anna Kormu🇫🇮 · Asier Lopez-Eiguren🇪🇸 · David J. Weir🇫🇮

    Models of symmetry breaking in the early universe can produce networks of cosmic strings threading 't Hooft-Polyakov monopoles. In certain cases there is a larger global symmetry group and the monopoles split into so-called semipoles. These networks are all known as cosmic necklaces. We carry out large-scale field theory simulations of the simplest model containing these objects, confirming that the energy density of networks of cosmic necklaces approaches scaling, i.e. that it remains a constant fraction of the background energy density. The number of monopoles per unit comoving string length is constant, meaning that the density fraction of monopoles decreases with time. Where the necklaces carry semipoles rather than monopoles, we perform the first simulations large enough to demonstrate that they also maintain a constant number per unit comoving string length. We also compare our results to a number of analytical models of cosmic necklaces, finding that none explains our results. We put forward evidence that annihilation of poles on the strings is controlled by a diffusive process, a possibility not considered before. The observational constraints derived in our previous work for necklaces with monopoles can now be safely applied to those with semipoles as well.

    ↳ astro-ph.COhep-phhep-thPRD(2018)·9 citations
31. 31*

    Composite phenomenology as a target for lattice QCD

    Thomas DeGrand🇺🇸 · Ethan Neil🇺🇸

    Some recent beyond Standard Model phenomenology is based on new strongly interacting dynamics of $SU(N)$ gauge fields coupled to various numbers of fermions. When $N=3$ these systems are analogues of QCD, although the fermion masses are typically different from -- and heavier than -- the ones of real world QCD. Many quantities needed for phenomenology from these models have been computed on the lattice. We are writing a guide for these phenomenologists, telling them about lattice results. We'll tell you (some of) what they are interested in knowing.

    ↳ hep-lathep-phPoS(2018)·2 citations
32. 32*

    T-dual cosmological solutions in double field theory

    Robert Brandenberger🇨🇦 · Renato Costa🇨🇦 · Guilherme Franzmann🇨🇦 · Amanda Weltman🇿🇦

    We investigate the cosmological solutions coming from the double field theory equations of motion after coupling a matter source to them. Assuming constant dilaton and imposing the section condition with respect to the regular coordinates leads to a universe dominated by momentum modes while imposing the section condition with respect to the dual coordinates naturally leads to a universe dominated by momentum modes. We show that both regimes have asymptotic behaviours related by T-duality. This hints towards defining a duality between the clocks considered in each regime and interpreting winding modes as being radiation from the point of view of a Euclidean time.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2019)·35 citations
33. 33*

    Gravitational Wave Decay into Dark Energy

    Paolo Creminelli🇮🇹 · Matthew Lewandowski🇫🇷 · Giovanni Tambalo🇮🇹 · Filippo Vernizzi🇫🇷

    We study the decay of gravitational waves into dark energy fluctuations $\pi$, through the processes $\gamma \to \pi \pi$ and $\gamma \to \gamma \pi$, made possible by the spontaneous breaking of Lorentz invariance. Within the EFT of Dark Energy (or Horndeski/beyond Horndeski theories) the first process is large for the operator $\frac{1}{2}{\tilde{m}}_4^2(t)\delta g^{00}\left({}^{(3)}R+\delta K_{\mu }^{\nu }\delta K_{\nu }^{\mu }-\delta K^2\right)$, so that the recent observations force ${\tilde{m}}_4=0$ (or equivalently ${\alpha }_{\mathrm{H}}=0$). This constraint, together with the requirement that gravitational waves travel at the speed of light, rules out all quartic and quintic GLPV theories. Additionally, we study how the same couplings affect the propagation of gravitons at loop order. The operator proportional to ${\tilde{m}}_4^2$ generates a calculable, non-Lorentz invariant higher-derivative correction to the graviton propagation. The modification of the dispersion relation provides a bound on ${\tilde{m}}_4^2$ comparable to the one of the decay. Conversely, operators up to cubic Horndeski do not generate sizeable higher-derivative corrections.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2018)·173 citations
34. 34*

    Quantum measurement and fuzzy dark matter

    Adam D. Helfer🇺🇸

    It has been suggested that dark matter is a superfluid of particles whose masses are on the rough order of $10^{-22}$ eV. Since the occupation numbers are huge, the state is coherent, and the speeds typical of orbital velocities in halos, it has generally been assumed that a classical effective non-relativistic treatment is adequate. However, the Compton wavelength would be $\sim 1\mathrm{pc}$, and around the Compton scale concerns about some aspects of quantum measurement theory, known in principle but not quantitatively significant in previous cases, become pronounced. I estimate here the stress--energy operator, averaged over a few Compton wavelengths; a rough but useful approximation has a remarkably simple form. Conventional quantum measurement theory gives physically unacceptable results: a thought-experiment to measure the stress--energy is described which would involve only a modest apparatus but would excite particles in the observation volume to relativistic energies; these particles would escape the Galaxy, and there would be a substantial violation of energy conservation. Related foundational questions come up: the meaning of measurements of observables with continuous spectra, and the problem of predicting when measurements occur. The effective classical theory of fuzzy dark matter is not affected; however, the underlying quantum theory cannot be regarded as satisfactory without resolving these issues. But we may interpret the results more broadly. The macroscopic Compton scale amplifies inadequacies of measurement theory which have not previously seemed pressing.

    ↳ gr-qcastro-ph.GAhep-phhep-th+1PRD(2018)·3 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.