Wed·Mar 11, 2020Wednesday·March 11, 2020

1. 01*

   Semileptonic decays of $D_{(s)}$ mesons

   Zhao-Qian Yao🇨🇳 · Daniele Binosi🇮🇹 · Zhu-Fang Cui🇨🇳 · Craig D. Roberts🇨🇳 · Shu-Sheng Xu🇨🇳 · Hong-Shi Zong🇨🇳

   A symmetry-preserving continuum approach to meson bound-states in quantum field theory, employed elsewhere to describe numerous $\pi$- and $K$-meson electroweak processes, is used to analyse leptonic and semileptonic decays of $D_{(s)}$ mesons. Each semileptonic transition is conventionally characterised by the value of the dominant form factor at $t=0$ and the following results are obtained herein: $f_{+}^{D_s\to K}(0)=0.673(40)$; $f_{+}^{D\to \pi }(0)=0.618(31)$; and $f_{+}^{D\to K}(0)=0.756(36)$. Working with the computed $t$-dependence of these form factors and standard averaged values for $|V_{cd}|$, $|V_{cs}|$, one arrives at the following predictions for the associated branching fractions: ${\mathcal{B}}_{D_s^{+}\to K^0{e}^{+}{\nu }_e}=3.31(33)\times 10^{-3}$; ${\mathcal{B}}_{D^0\to {\pi }^{-}{e}^{+}{\nu }_e}=2.73(22)\times 10^{-3}$; and ${\mathcal{B}}_{D^0\to K^{-}{e}^{+}{\nu }_e}=3.83(28)$%. Alternatively, using the calculated $t$-dependence, agreement with contemporary empirical results for these branching fractions requires $|V_{cd}|=0.221(9)$, $|V_{us}|=0.953(34)$. With all $D_{(s)}$ transition form factors in hand, the nature of SU$(3)$-flavour symmetry-breaking in this array of processes can be analysed; and just as in the $\pi$-$K$ sector, the magnitude of such effects is found to be determined by the scales associated with emergent mass generation in the Standard Model, not those originating with the Higgs mechanism.

   hep-phhep-exhep-latnucl-ex+1PRD(2020)·18 citations
2. 02*

   Fundamental Properties of the Proton in Light-Front Zero Modes

   Xiangdong Ji🇺🇸

   For a proton in the infinite momentum frame, its wave function contains a zero-momentum part (light-front zero-modes) originated from the modification of the QCD vacuum in the presence of the valence quarks, exhibiting a light-front long-range order in the quantum state. This ``non-travelling'' component of the proton contributes to its fundamental properties, including the mass and spin, as well as the naive-time-reversal-odd correlations between transverse momentum and spin. The large momentum effective theory (LaMET) provides a theoretical approach to study the physical properties of the proton's zero-mode ``condensate'' through lattice simulations.

   hep-phhep-latnucl-thNPB(2020)·41 citations
3. 03*

   Fluctuating temperature and baryon chemical potential in heavy-ion collisions and the position of the critical end point in the effective QCD phase diagram

   Alejandro Ayala🇲🇽 · Saul Hernandez-Ortiz🇲🇽 · Luis A. Hernandez🇲🇽 · Victor Knapp-Perez🇲🇽 · Renato Zamora🇨🇱

   We use the linear sigma model with quarks to locate the critical end point in the effective QCD phase diagram accounting for fluctuations in temperature and quark chemical potential. For this purpose, we use the non-equilibrium formalism provided by the superstatistics framework. We compute the effective potential in the high- and low-temperature approximations up to sixth order and include the contribution of ring diagrams to account for plasma screening effects. We fix the model parameters from relations between the thermal sigma and pion masses imposing a first order phase transition at zero temperature and a finite critical value for the baryon chemical potential that we take of order of the nucleon mass. We find that the CEP displacement due to fluctuations in temperature and/or quark chemical potential is almost negligible.

   hep-phnucl-thPRD(2020)·14 citations
4. 04*

   Light-quark flavours in a triangle

   Renxin Xu (PKU)🇨🇳

   All of the light flavors seem to work well for bulk strong matter at pressure free, which could be manifested diversely in the form of compact star and strange nugget. Observational tests are discussed.

   hep-phastro-ph.HEnucl-thSCPMA(2020)·7 citations
5. 05*

   Second-order Charge Currents and Stress Tensor in Chiral System

   Shi-Zheng Yang🇨🇳 · Jian-Hua Gao🇨🇳 · Zuo-Tang Liang🇨🇳 · Qun Wang🇨🇳

   We solve the Wigner equation for massless spin-1/2 charged fermions near global equilibrium. The Wigner function can be obtained order by order in the power expansion of the vorticity and electromagnetic field. The Wigner function has been derived up to the second order from which the non-dissipative charge currents and the stress tensor can be obtained. The charge and energy densities and the pressure have contributions from the vorticity and electromagnetic field at the second order. The vector and axial Hall currents can be induced along the direction orthogonal to the vorticity and electromagnetic field at the second order. We also find that the trace anomaly emerges natually in renormalizing the stress tensor by including the quantum correction from the electromagnetic field.

   hep-phhep-thnucl-thPRD(2020)·27 citations
6. 06*

   Short review about the MSSM with three right-handed neutrinos (MSSM3RHN)

   M. C. Rodriguez🇧🇷

   We give a review about the Minimal Supersymmetric Standard Model with three right-handed neutrinos (MSSM3RHN). We, first introduce the minimal set of fields to built this model in their superfields formalism. After it, we build the lagrangian of the model in the superspace formalism and also introduce the soft terms to break SUSY. We show how to get masses to the neutrinos and sneutrinos in this model.

   hep-ph4 citations
7. 07*

   Improved MSSM Higgs mass calculation using the 3-loop FlexibleEFTHiggs approach including $x_t$-resummation

   Thomas Kwasnitza · Dominik Stöckinger · Alexander Voigt

   We present an improved calculation of the light CP-even Higgs boson pole mass in the MSSM based on the FlexibleEFTHiggs hybrid method. The calculation resums large logarithms to all orders and includes power-suppressed terms at fixed order. It uses state-of-the-art 2- and 3-loop matching of the quartic Higgs coupling and renormalization group running up to 4-loop, resulting in a resummation of large logarithmic corrections up to N${}^3$LL level. A conceptually novel ingredient is the expansion of the matching conditions in terms of high-scale MSSM parameters instead of SM parameters. In this way leading terms in the stop-mixing parameter are effectively resummed, leading to an improved numerical convergence of the perturbative expansion. Furthermore, the avoidance of double counting of loop corrections is more transparent than in other approaches and more independent of the high-scale model. We present numerical results and a detailed discussion of theoretical uncertainties for standard benchmark scenarios.

   hep-phJHEP 07 (2020) 197
8. 08*

   Parton models and frame independence of high-energy cross-sections

   O.V. Kancheli🇷🇺

   We describe some ambiguities which take place when on calculates the cross-sections in parton models at high energies and the connected limitations on the asymptotic of high energy amplitudes that follows from the conditions of boost-invariance of cross-sections. It turns out that the resulting constraints are of the same type as the following from the t-channel unitarity conditions.~ So that on can suppose that this similarity, by their nature, has much more general grounds.

   hep-ph2 citations
9. 09*

   Isentropic evolution of the matter in heavy-ion collisions and the search for the critical endpoint

   Mario Motta🇮🇹 · Rainer Stiele🇮🇹 · Wanda Maria Alberico🇮🇹 · Andrea Beraudo🇮🇹

   We study the isentropic evolution of the matter produced in relativistic heavy-ion collisions for various values of the entropy-per-baryon ratio of interest for the ongoing and future experimental searches for the critical endpoint (CEP) in the QCD phase diagram: these includes the current Beam-Energy-Scan (BES) program at RHIC and the fixed-target collisions foreseen for the near future at various facilities. We describe the hot-dense matter through two different effective Lagrangians: the PNJL (Polyakov-Nambu-Jona-Lasinio) and the PQM (Polyakov-quark-meson) models. We focus on quantities expected to have a direct experimental relevance: the speed of sound, responsible for the collective acceleration of the fireball, and the generalized susceptibilities, connected to the cumulants of the distributions of conserved charges. In principle, they should affect the momentum spectra and the event-by-event fluctuations of the yields of identified particles. Taking realistic values for the initial temperature and the entropy-per-baryon ratio we study the temporal evolution of the above quantities looking for differences along isentropic trajectories covering different regions of the QCD phase diagram, passing far or close to the CEP or even intersecting the first-order critical line.

   hep-phnucl-thEPJC(2020)·22 citations
10. 10*

    A model of diffractive excitation in $pp$ collisions at high energies

    M. Broilo🇧🇷 · V. P. Goncalves🇧🇷 · P. V. R. G. Silva🇧🇷

    A phenomenological model for the description of the single and double diffractive excitation in $pp$ collisions at high energies is presented. Considering the Good -- Walker approach, we propose a model for the eigenstates of the scattering operator and for the treatment of the interaction between them, with the high energy behavior of the cross section driven by perturbative QCD. The behavior of the total, elastic, single and double diffractive cross sections are analyzed and predictions for the energies of Run 3 of the LHC and those of the Cosmic Rays experiments are derived. We demonstrate that the model describes the current data for the energy dependence of the cross sections. A comparison with the recent data for the $\rho$ parameter and the differential elastic cross section are also presented and shortcomings of the current model are discussed.

    hep-phhep-exPRD(2020)·7 citations
11. 11*

    Extracting the Transverse Momentum Dependent Polarizing Fragmentation Functions

    Daniel Callos🇺🇸 · Zhong-Bo Kang🇺🇸 · John Terry🇺🇸

    We demonstrate that spontaneous transverse polarization of Lambda baryon ($\Lambda$) production in $e^{+}{e}^{-}$ annihilation can be described using the transverse momentum dependent polarizing fragmentation functions (TMD PFFs). Using a simple Gaussian model, we perform an extraction of the TMD PFFs by fitting the BELLE collaboration's recent measurement of the $\Lambda$ transverse polarization in back-to-back $\Lambda +h$ production in $e^{+}{e}^{-}$ collisions, $e^{-}+e^{+}\to {\Lambda }^{\uparrow }+h+X$. We find that this simple model accurately describes the experimental data for $\Lambda$ production associated with pions and kaons, and we are able to determine TMD PFFs for different quark flavors. We use these newly extracted TMD PFFs to make predictions for the transverse polarization of $\Lambda$ produced in semi-inclusive deep inelastic scattering at a future electron-ion collider, and find that such a polarization is around $10\%$ and should be measurable.

    hep-phhep-exnucl-exnucl-thPRD(2020)·66 citations
12. 12*

    Covariant model for the Dalitz decay of the $N(1535)$ resonance

    G. Ramalho🇧🇷 · M.T. Peña🇵🇹

    We develop a covariant model for the ${\gamma }^{\ast }N\to N(1535)$ transition in the timelike kinematical region, the region where the square momentum transfer $q^2$ is positive. Our starting point is the covariant spectator quark model constrained by data in the spacelike kinematical region ($Q^2=-q^2>0$). The model is used to estimate the contributions of valence quarks to the transition form factors, and one obtains a fair description of the Dirac form factor at intermediate and large $Q^2$. For the Pauli form factor there is evidence that beyond the quark-core contributions there are also significant contributions of meson cloud effects. Combining the quark-core model with an effective description of the meson cloud effects, we derive a parametrization of the spacelike data that can be extended covariantly to the timelike region. This extension enabled us to estimate the Dalitz decay widths of the $N(1535)$ resonance, among other observables. Our calculations can help in the interpretation of the present experiments at HADES ($pp$ collisions and others).

    hep-phhep-exnucl-exnucl-thPRD(2020)·26 citations
13. 13*

    Hadronic vacuum polarization: $(g-2{)}_{\mu }$ versus global electroweak fits

    Andreas Crivellin🇨🇭 · Martin Hoferichter🇨🇭 · Claudio Andrea Manzari🇨🇭 · Marc Montull🇨🇭

    Hadronic vacuum polarization (HVP) is not only a critical part of the Standard Model (SM) prediction for the anomalous magnetic moment of the muon $(g-2{)}_{\mu }$, but also a crucial ingredient for global fits to electroweak (EW) precision observables due to its contribution to the running of the fine-structure constant encoded in $\Delta {\alpha }_{\text{had}}^{(5)}$. We find that with modern EW precision data, including the measurement of the Higgs mass, the global fit alone provides a competitive, independent determination of $\Delta {\alpha }_{\text{had}}^{(5)}{|}_{\text{EW}}=270.2(3.0)\times 10^{-4}$. This value actually lies below the range derived from $e^{+}{e}^{-}\to \text{hadrons}$ cross-section data, and thus goes into the opposite direction as would be required if a change in HVP were to bring the SM prediction for $(g-2{)}_{\mu }$ into agreement with the Brookhaven measurement. Depending on the energy where the bulk of the changes in the cross section occurs, reconciling experiment and SM prediction for $(g-2{)}_{\mu }$ by adjusting HVP would thus not necessarily weaken the case for physics beyond the SM (BSM), but to some extent shift it from $(g-2{)}_{\mu }$ to the EW fit. We briefly explore some options of BSM scenarios that could conceivably explain the ensuing tension.

    hep-phhep-exhep-latnucl-ex+1PRL(2020)·266 citations
14. 14*

    Heavy Thermal Relics from Zombie Collisions

    Eric David Kramer🇮🇱 · Eric Kuflik🇮🇱 · Noam Levi🇮🇱 · Nadav Joseph Outmezguine🇮🇱 · Joshua T. Ruderman🇺🇸

    We propose a new thermal freezeout mechanism which results in dark matter masses exceeding the unitarity bound by many orders of magnitude, without violating perturbative unitarity or modifying the standard cosmology. The process determining the relic abundance is $\chi {\zeta }^{†}\to \zeta \zeta$, where $\chi$ is the dark matter candidate. For $m_{\zeta }<m_{\chi }<3m_{\zeta }$, $\chi$ is cosmologically long-lived and scatters against the exponentially more abundant $\zeta$. Therefore, such a process allows for exponentially heavier dark matter for the same interaction strength as a particle undergoing ordinary $2\to 2$ freezeout; or equivalently, exponentially weaker interactions for the same mass. We demonstrate this mechanism in a leptophilic dark matter model, which allows for dark matter masses up to $10^9$ GeV.

    hep-phPRL(2021)·57 citations
15. 15*

    The QCD Axion at Finite Density

    Reuven Balkin🇩🇪 · Javi Serra🇩🇪 · Konstantin Springmann🇩🇪 · Andreas Weiler🇩🇪

    We show how the properties of the QCD axion change in systems at finite baryonic density, such as neutron stars. At nuclear saturation densities, where corrections can be reliably computed, we find a mild reduction of the axion mass and up to an order of magnitude enhancement in the model-independent axion coupling to neutrons. At moderately higher densities, if realized, meson (kaon) condensation can trigger axion condensation. We also study the axion potential at asymptotically large densities, where the color-superconducting phase of QCD potentially leads to axion condensation, and the mass of the axion is generically several orders of magnitude smaller than in vacuum due to the suppressed instantons. Several phenomenological consequences of the axion being sourced by neutron stars are discussed, such as its contribution to their total mass, the presence of an axionic brane, or axion-photon conversion in the magnetosphere.

    hep-phastro-ph.HEnucl-thJHEP(2020)·79 citations
16. 16*

    Gravitational Interactions and Neutrino Masses

    Hooman Davoudiasl🇺🇸

    We describe a scenario where the smallness of neutrino masses is related to a global symmetry that is only violated by quantum gravitational effects. The coupling of neutrinos to gauge singlet right-handed fermions is attributed to symmetry preserving gravitational operators suppressed by the Planck mass, in this framework. The proposed scenario leads to axion particles that decay into neutrinos, which could be probed through cosmological measurements and may help explain the Hubble parameter tension. Depending on the details of the implementation, the scenario could provide axion dark matter candidates.

    hep-phastro-ph.COPRD(2020)·7 citations
17. 17*

    Longitudinal eccentricity decorrelations in heavy ion collisions

    Arabinda Behera🇺🇸 · Maowu Nie🇨🇳 · Jiangyong Jia🇺🇸

    In heavy-ion collisions, the harmonic flow $V_n$ of final-state particles are driven by the eccentricity vector ${\mathcal{E}}_n$ that describe the shape of the initial fireball projected in the transverse plane. It is realized recently that the structure and shape of the fireball, and consequently the ${\mathcal{E}}_n$, fluctuate in pseudorapidity $\eta$ in a single event, ${\mathcal{E}}_n(\eta )$. This leads to eccentricity decorrelation between different $\eta$, driving the longitudinal flow decorrelations observed in the experiments. Using a Glauber model with a paramerterized longitudinal structure, we have estimated the eccentricity decorrelations and related them to the measured flow decorrelation coefficients for elliptic flow $n=2$ and triangular flow $n=3$. We investigated the dependence of eccentricity decorrelations on the choice of collision system in terms of the size, asymmetry and deformation of the nuclei. We found that these nuclear geometry effects lead to significant and characteristic patterns on the eccentricity decorrelations, which describe the measured ratios of the flow decorrelations between Xe+Xe and Pb+Pb collisions. These patterns can be searched for using existing experimental data at RHIC and the LHC, and if confirmed, they will provide a mean to improve our understanding of the initial state of the heavy-ion collisions.

    ↳ nucl-thhep-phnucl-exPRResearch(2020)·16 citations
18. 18*

    The effect of stout smearing on the phase diagram from multiparameter reweigthing in lattice QCD

    Matteo Giordano🇭🇺 · Kornel Kapas🇭🇺 · Sandor D. Katz🇭🇺 · Daniel Nogradi🇭🇺 · Attila Pasztor🇭🇺

    The phase diagram and the location of the critical endpoint (CEP) of lattice QCD with unimproved staggered fermions on a $N_t=4$ lattice was determined fifteen years ago with the multiparameter reweighting method by studying Fisher zeros. We first reproduce the old result with an exact algorithm (not known at the time) and with statistics larger by an order of magnitude. As an extension of the old analysis we introduce stout smearing in the fermion action in order to reduce the finite lattice spacing effects. First we show that increasing the smearing parameter $\rho$ the crossover at $\mu =0$ gets weaker, i.e., the leading Fisher zero gets farther away from the real axis. Furthermore as the chemical potential is increased the overlap problem gets severe sooner than in the unimproved case, therefore shrinking the range of applicability of the method. Nevertheless certain qualitative features remain, even after introducing the smearing. Namely, at small chemical potentials the Fisher zeros first get farther away from the real axis and later at around $a{\mu }_q=0.1-0.15$ they start to get closer, i.e., the crossover first gets weaker and later stronger as a function of $\mu$. However, because of the more severe overlap problem the CEP is out of reach with the smeared action.

    ↳ hep-lathep-phnucl-thPRD(2020)·17 citations
19. 19*

    Monte Carlo study of the tip region of branching random walks evolved to large times

    Anh Dung Le🇫🇷 · Alfred H. Mueller🇺🇸 · Stéphane Munier🇫🇷

    We implement a discretization of the one-dimensional branching Brownian motion in the form of a Monte Carlo event generator, designed to efficiently produce ensembles of realizations in which the rightmost lead particle at the final time $T$ is constrained to have a position $X$ larger than some predefined value $X_{\text{min}}$. The latter may be chosen arbitrarily far from the expectation value of $X$, and the evolution time after which observables on the particle density near the lead particle are measured may be as large as $T\sim 10^4$. We then calculate numerically the probability distribution $p_n(\Delta x)$ of the number $n$ of particles in the interval $[X-\Delta x,X]$ as a function of $\Delta x$. When $X_{\text{min}}$ is significantly smaller than the expectation value of the position of the rightmost lead particle, i.e. when $X$ is effectively unconstrained, we check that both the mean and the typical values of $n$ grow exponentially with $\Delta x$, up to a linear prefactor and to finite-$T$ corrections. When $X_{\text{min}}$ is picked far ahead of the latter but within a region extending over a size of order $\sqrt{T}$ to its right, the mean value of the particle number still grows exponentially with $\Delta x$, but its typical value is lower by a multiplicative factor consistent with $e^{-\zeta \Delta x^{2/3}}$, where $\zeta$ is a number of order unity. These numerical results bring strong support to recent analytical calculations and conjectures in the infinite-time limit.

    ↳ cond-mat.stat-mechhep-ph1 citation
20. 20*

    Loop Equation and Exact Soft Anomalous Dimension in N=4 Super Yang-Mills

    Simone Giombi🇺🇸 · Shota Komatsu🇺🇸

    BPS Wilson loops in supersymmetric gauge theories have been the subjects of active research since they are often amenable to exact computation. So far most of the studies have focused on loops that do not intersect. In this paper, we derive exact results for intersecting 1/8 BPS Wilson loops in N=4 supersymmetric Yang-Mills theory, using a combination of supersymmetric localization and the loop equation in 2d gauge theory. The result is given by a novel matrix-model-like representation which couples multiple contour integrals and a Gaussian matrix model. We evaluate the integral at large N, and make contact with the string worldsheet description at strong coupling. As an application of our results, we compute exactly a small-angle limit (and more generally near-BPS limits) of the cross anomalous dimension which governs the UV divergence of intersecting Wilson lines. The same quantity describes the soft anomalous dimension of scattering amplitudes of W-bosons in the Coulomb branch.

    ↳ hep-thhep-phJHEP(2020)·6 citations
21. 21*

    Test of Nonlocal Hidden Variable Theory by Leggett Inequality in High Energy Physics

    Abdul Sattar Khan🇨🇳 · Jun-Li Li🇨🇳 · Cong-Feng Qiao🇨🇳

    The Leggett inequality is a constraint on the bipartite correlation that admits certain types of non-localities. Existing tests mainly focused on the electromagnetic systems where measurement apparatus are assumed to be projective and sharp. However, in nature there are interactions that do not obey the same conservation laws for photon, and the actual measurements may subject to unavoidable uncertainties due to the fundamental physical principles. In this work, we generalize the Leggett inequality to incorporate the measurements that are unsharp and/or biased. It is found that the parity violation in nature provides a spontaneous implementation of an unsharp measurement for the spin of hyperon. A fine structured Leggett inequality for hyperon decays characterized by the asymmetry parameters is obtained and its violation is found which could be observed with the yet obtained data in experiment, like BESIII and Belle.

    ↳ quant-phhep-phPRD(2020)·6 citations
22. 22*

    Identification of perturbative ambiguity canceled against bion

    Okuto Morikawa🇯🇵 · Hiromasa Takaura🇯🇵

    It was conjectured that bions, semi-classical objects found in a compactified spacetime, are responsible for the cancellation of the so-called renormalon ambiguities. Contrary to the conjecture, we argue that the ambiguity due to the bion corresponds to the proliferation of Feynman diagrams. We point out that the amplitudes of almost all Feynman diagrams are enhanced due to modifications of the infrared structure of perturbation theory upon an $S^1$ compactification and twisted boundary conditions. Our findings clarify the role of the semi-classical object in resurgence structure, which has been a controversial issue in recent years.

    ↳ hep-thhep-lathep-phPLB(2020)·11 citations
23. 23*

    A landscape of orientifold vacua

    Federico Carta🇩🇪 · Jakob Moritz🇺🇸 · Alexander Westphal🇩🇪

    We present a vast landscape of O3/O7 orientifolds that descends from the famous set of complete intersection Calabi-Yau threefolds (CICY). We give distributions of topological data relevant for phenomenology such as the orientifold-odd Hodge numbers, the D3-tadpole, and multiplicities of O3 and O7-planes. Somewhat surprisingly, almost all of these orientifolds have conifold singularities whose deformation branches are projected out by the orientifolding. However, they can be resolved, so most of the orientifolds actually descend from a much larger and possibly new set of CY threefolds that can be reached from the CICYs via conifold transitions. We observe an interesting class of $\mathcal{N}=1$ geometric transitions involving colliding O-planes. Finally, as an application, we use our dataset to produce examples of orientifolds that satisfy the topological requirements for the existence of ultra-light throat axions (\textit{thraxions}) as proposed in \cite{Hebecker:2018yxs}. The database can be accessed at https://www.desy.de/~westphal/orientifold_webpage/cicy_orientifolds.html

    ↳ hep-thhep-phJHEP(2020)·53 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.