Tue·Mar 2, 2021Tuesday·March 2, 2021

1. 01*

   Hybrid model of proton structure functions

   S. A. Kulagin🇷🇺 · V. V. Barinov🇷🇺

   We develop a "hybrid" model of the proton inelastic structure functions applicable in a wide region of invariant mass of produced states $W$ and invariant momentum transfer $Q$ including deep inelastic scattering (DIS), nucleon resonance production as well as the region close to inelastic threshold. DIS is described in terms of the parton distributions together with higher-twist corrections from an available global QCD fit. The resonant part is addressed in terms of the Breit-Wiegner contributions from five states including the $\Delta (1232)$ resonance, the $N(1440)$ Roper resonance, and three effective resonances describing the second and third resonance regions. The couplings of the nucleon resonances to photon are described in terms of helicity amplitudes. The nonresonant background is addressed in terms of DIS structure functions smoothly extrapolated to low-$W$ and low-$Q$ values with the proper behavior at the real photon limit $Q^2=0$ as well as near the inelastic threshold. We independently treat the transverse $F_T$ and the longitudinal $F_L$ structure function and fix the model parameters from a global analysis of the world hydrogen electroproduction and photoproduction cross-section data. We demonstrate a very good performance of the model by comparing our predictions with data on differential cross sections and the structure functions $F_2$ and $R=F_L/F_T$.

   hep-phhep-exnucl-exnucl-thPRC(2022)·4 citations
2. 02*

   Progress in Higgs inflation

   Dhong Yeon Cheong🇰🇷 · Sung Mook Lee🇰🇷 · Seong Chan Park🇰🇷

   We review the recent progress in Higgs inflation focusing on Higgs-$R^2$ inflation, primordial black hole production and the $R^3$ term.

   hep-phastro-ph.COgr-qchep-thJ.Korean Phys.Soc.(2021)·39 citations
3. 03*

   Electroweak Phase Transition in an Inert Complex Triplet Model

   Mohammad Javad Kazemi🇮🇷 · Shehu AbdusSalam🇮🇷

   We study the dynamics of electroweak phase transition in a simple extension of the Standard Model where the Higgs sector is extended by adding an $SU(2{)}_L$-triplet with hypercharge Y=2. By making random scans over the parameters of the model, we show that there are regions consistent with constraints from collider experiments and the requirement for a strong first-order electroweak phase transition which is needed for electroweak baryogenesis. Further, we also study the power spectrum of the gravitational waves which can be generated due to the first-order phase transitions. Moreover, the detectability of these gravitational waves, via future space-based detectors, is discussed.

   hep-phgr-qcPRD(2021)·8 citations
4. 04*

   Vector dark matter from split SU(2) gauge bosons

   Zexi Hu🇨🇳 · Chengfeng Cai🇨🇳 · Yi-Lei Tang🇨🇳 · Zhao-Huan Yu🇨🇳 · Hong-Hao Zhang🇨🇳

   We propose a vector dark matter model with an exotic dark SU(2) gauge group. Two Higgs triplets are introduced to spontaneously break the symmetry. All of the dark gauge bosons become massive, and the lightest one is a viable vector DM candidate. Its stability is guaranteed by a remaining Z_2 symmetry. We study the parameter space constrained by the Higgs measurement data, the dark matter relic density, and direct and indirect detection experiments. We find numerous parameter points satisfying all the constraints, and they could be further tested in future experiments. Similar methodology can be used to construct vector dark matter models from an arbitrary SO(N) gauge group.

   hep-phastro-ph.COhep-exJHEP(2021)·14 citations
5. 05*

   Extra gauge bosons and lepton flavor universality violation in ${\rm Y}$ and $B$ meson decays

   Cristian H. García-Duque🇨🇴 · J. H. Muñoz🇨🇴 · Néstor Quintero🇨🇴 · Eduardo Rojas🇨🇴

   Lepton flavor universality can be tested through the ratio of semileptonic $B$ meson decays and leptonic ${\rm Y}$ meson decays, with ${\rm Y}\equiv {\rm Y}(nS)$ ($n=1,2,3$). For the charged-current transitions $b\to c\tau {\bar{\nu }}_{\tau }$, discrepancies between the experiment and the Standard Model (SM) have been observed in recent years by different flavor facilities such as BABAR, Belle, and LHCb. While for the neutral-current transitions $b\bar{b}\to \tau \bar{\tau }$, the BABAR experiment reported recently a new measurement of leptonic decay ratio $R_{{\rm Y}(3S)}=\mathrm{BR}({\rm Y}(3S)\to {\tau }^{+}{\tau }^{-})/\mathrm{BR}({\rm Y}(3S)\to {\mu }^{+}{\mu }^{-})$, showing an agreement with the SM at the $1.8\sigma$ level. In light of this new BABAR result and regarding the connection between new physics (NP) interpretations to the charged-current $b\to c\tau {\bar{\nu }}_{\tau }$ anomalies and neutral-current $b\bar{b}\to \tau \bar{\tau }$ processes, in this study, we revisit the NP consequences of this measurement within a simplified model with extra massive gauge bosons that coupled predominantly to left-handed leptons of the third-generation. We show that the BABAR measurement of $R_{{\rm Y}(3S)}$ cannot easily be accommodated (within its experimental $1\sigma$ range) together with the other $b\to c\tau {\bar{\nu }}_{\tau }$ data, hinting toward a new anomalous observable.

   hep-phhep-exPRD(2021)·7 citations
6. 06*

   Effect of symmetrical frequency chirp on pair production

   Kun Wang🇨🇳 · Xuehua Hu🇨🇳 · Sayipjamal Dulat🇨🇳 · B. S. Xie🇨🇳

   By using Dirac-Heisenberg-Wigner formalism we study electron-positron pair production for linear, elliptic, nearly circular and circular polarizations of electric fields with symmetrical frequency chirp, and we obtain Momentum spectra and pair yield. The difference of results among polarized fields is obvious for the small chirp. When the chirp parameter increases, the momentum spectra tend to exhibit the multiphoton pair generation that is characterized by the multi-concentric ring structure. The increase of number density is also remarkable compared to the case of asymmetrical frequency chirp. Note that the dynamically assisted Schwinger Mechanism plays an important role for the enhanced pair production in the symmetrical frequency chirp.

   hep-phquant-phChin.Phys.B(2021)·8 citations
7. 07*

   Renormalization-Group Evolution of the None-local Matrix Element of $B$-meson In QCD and $B\to \pi$ transition form factor

   Sheng Lü🇨🇳 · Mao-Zhi Yang🇨🇳

   We consider the renormalization-group evolution of the matrix element of $⟨0|\bar{q}(z{)}_{\beta }[z,0]b(0{)}_{\alpha }|\bar{B}⟩$, which can be used to define the distribution amplitudes for $B$ meson and widely applied in studies of $B$ meson decays. The contribution to the renormalization constant of the non-local operator $\bar{q}(z{)}_{\beta }[z,0]b(0{)}_{\alpha }$ is considered up to one-loop order in QCD. Since the quark fields in this operator are not directly coupled fields, momentum can not flow freely through this non-local operator. Momentum involved in this operator can be treated stringently in coordinate space. We find that the ultraviolet divergences regulated by dimensional parameter $ϵ$ cancel with each other, and the evolution effect vanishes. The matrix element $⟨0|\bar{q}(z{)}_{\beta }[z,0]b(0{)}_{\alpha }|\bar{B}⟩$ escapes from the renormalization-group evolution. We then apply the matrix element in calculating $B\to \pi$ transition form factor, where the matrix element is obtained by using the $B$ meson wave function calculated in QCD-inspired potential model. By comparing with experimental data for the semileptonic decay of $B\to \pi \ell \nu$ and light-cone sum rule calculation, we analyse the perturbative and non-perturbative contributions to $B\to \pi$ transition form factor in the frame work of perturbative QCD approach. We find that the effectiveness of the suppression of Sudakov factor to soft contribution depends on the end-point behavior of $B$ meson wave function, and with the $B$-meson wave function used in this work, soft contribution can not be well suppressed. The hard contribution to the $B\to \pi$ transition form factor is about 59\%, and soft contribution can be as large as 41\% in the naive calculation. To make the perturbative calculation reliable, a soft momentum cutoff in the calculation and soft form factor have to be introduced.

   hep-phNPB(2021)·7 citations
8. 08*

   Precise evaluation of $h\to c\bar{c}$ and axion-like particle production

   Shi-Yuan Li🇨🇳 · Zhen-Yang Li🇨🇳 · Peng-Cheng Lu🇨🇳 · Zong-Guo Si🇨🇳

   We study the decay of the SM Higgs boson to a massive charm quark pair at the next-to-next-to-leading order QCD and next-to-leading order electroweak. At the second order of QCD coupling, we consider the exact calculation of flavour-singlet contributions where the Higgs boson couples to the internal top and bottom quark. Helpful information on the running mass effects related to Yukawa coupling may be obtained by analyzing this process. High precision production for $h\to c\bar{c}$ within the SM makes it possible to search for new physics that may induce relatively large interactions related to the charm quark. As an example, we evaluate the axion-like particle associate production with a charm quark pair in the Higgs decay and obtain some constraints for the corresponding parameters under some assumptions.

   hep-phCPC(2021)·3 citations
9. 09*

   Recent progresses on QCD phases in a strong magnetic field -- views from Nambu--Jona-Lasinio model

   Gaoqing Cao🇨🇳

   In this review, we summarize recent progress on the possible phases of quantum chromodynamics (QCD) in the presence of a strong magnetic field, mainly from the views of the chiral effective Nambu--Jona-Lasinio model. Four kinds of phase transitions are explored in detail: chiral symmetry breaking and restoration, neutral pseudoscalar superfluidity, charged pion superfluidity and charged rho superconductivity. In particular, we revisit the unsolved problems of inverse magnetic catalysis effect and competition between the chiral density wave and solitonic modulation phases. It is shown that useful results can be obtained by adopting self-consistent schemes.

   hep-phnucl-thEPJA(2021)·59 citations
10. 10*

    Rosenbluth separation of $\mathbf{d}{\mathbf{\sigma }}_{\mathbf{L}}/\mathbf{dt}$ and $\mathbf{d}{\mathbf{\sigma }}_{\mathbf{T}}/\mathbf{dt}$ in ${\mathbf{\pi }}^0$ deeply virtual electroproduction from the proton

    I. Korover🇺🇸 · R.G. Milner🇺🇸

    We report on a Rosenbluth separation using previously published data by the CLAS collaboration in Hall B, Jefferson Lab for exclusive ${\pi }^0$ deeply virtual electroproduction (DVEP) from the proton at a mean $Q^2$ of $\approx$ 2 (GeV/c)${}^2$. The central question we address is the applicability of factorization in ${\pi }^0$ DVEP at these kinematics. The results of our Rosenbluth separation clearly demonstrate the dominance of the longitudinal contribution to the cross section. The extracted longitudinal and transverse contributions are in agreement with previous data from Hall A at Jefferson Lab, but over a much wider $-t$ range (0.12 - 1.8 (GeV/c)${}^2$). The measured dominance of the longitudinal contribution at $Q^2\approx$ 2 (GeV/c)${}^2$ is consistent with the expectation of the handbag factorization theorem. We find that ${\sigma }_L(t)\sim 1/(-t)$ for $-t>$ 0.5 (GeV/c)${}^2$. Determination of both longitudinal and transverse contributions to the deeply virtual ${\pi }^0$ electroproduction cross section allows extraction of additional GPDs.

    hep-phnucl-exnucl-th2 citations
11. 11*

    Four-body decays $B_{(s)}\to (K\pi {)}_{S/P}(K\pi {)}_{S/P}$ in the perturbative QCD approach

    Zhou Rui🇨🇳 · Ya Li🇨🇳 · Hsiang-nan Li🇹🇼

    We investigate the four-body decays $B_{(s)}\to (K\pi {)}_{S/P}(K\pi {)}_{S/P}$ in the $K\pi$-pair invariant mass region around the $K^{\ast }(892)$ resonance in the perturbative QCD (PQCD) approach, where $(K\pi {)}_{S/P}$ denotes a $S$- or $P$-wave $K\pi$ configuration. The contributions from the $P$-wave resonance $K^{\ast }(892)$ and from possible $S$-wave components are included into the parametrization of the $K\pi$ two-meson distribution amplitudes, which are the nonperturbative inputs in this formalism. We calculate the branching ratio for each resonance and observe sizable $S$-wave contributions to the $B_s$ modes, well consistent with recently available LHCb data. We also deduce the polarization fractions for the $K^{\ast }{\bar{K}}^{\ast }$ final states, and compare our predictions to those in previous PQCD analyses of the corresponding two-body $B\to K^{\ast }{\bar{K}}^{\ast }$ decays. The polarization puzzle associated with the two $U$-spin related channels $B^0\to K^{\ast 0}{\bar{K}}^{\ast 0}$ and $B_s^0\to K^{\ast 0}{\bar{K}}^{\ast 0}$ still exists. In addition to direct $CP$ asymmetries, triple-product asymmetries and $S$-wave induced direct $CP$ asymmetries originating from the interference among various helicity amplitudes, are presented. It is shown that true triple-product asymmetries are rather small, while direct $CP$ asymmetries and $S$-wave-induced direct $CP$ asymmetries are significant in some decays. Our results will be subject to stringent tests with precise data from $B$ factories in the near future.

    hep-phJHEP(2021)·27 citations
12. 12*

    Cross sections of inclusive $\psi (2S)$ and $X(3872)$ production from $b$-hadron decays in $pp$ collisions and comparison with ATLAS and CMS data

    B. A. Kniehl🇩🇪 · G. Kramer🇩🇪 · I. Schienbein🇫🇷 · H. Spiesberger🇩🇪

    We study the cross sections for the inclusive production of $\psi (2S)$ and $X(3872)$ hadrons in $pp$ collisions at the LHC at two different center-of-mass energies and compare with experimental data obtained by the ATLAS, CMS, and LHCb collaborations.

    hep-phPRD(2021)·1 citation
13. 13*

    High-precision determination of the $K_{e3}$ radiative corrections

    Chien-Yeah Seng🇩🇪 · Daniel Galviz🇩🇪 · Mikhail Gorchtein🇩🇪 · Ulf-G. Meißner🇩🇪

    We report a high-precision calculation of the Standard Model electroweak radiative corrections in the $K\to \pi e^{+}\nu (\gamma )$ decay as a part of the combined theory effort to understand the existing anomaly in the determinations of $V_{us}$. Our new analysis features a chiral resummation of the large infrared-singular terms in the radiative corrections and a well-under-control strong interaction uncertainty based on the most recent lattice QCD inputs. While being consistent with the current state-of-the-art results obtained from chiral perturbation theory, we reduce the existing theory uncertainty from $10^{-3}$ to $10^{-4}$. Our result suggests that the Standard Model electroweak effects cannot account for the $V_{us}$ anomaly.

    hep-phhep-exhep-latnucl-ex+1PLB(2021)·35 citations
14. 14*

    Cold magnetized quark matter at finite density in a nonlocal chiral quark model

    S.A. Ferraris🇦🇷 · D. Gomez Dumm🇦🇷 · A.G. Grunfeld🇦🇷 · N.N. Scoccola🇦🇷

    We study the behavior of two-flavor dense quark matter under the influence of an external magnetic field in the framework of a nonlocal chiral quark model with separable interactions. The nonlocality is incorporated in the model by using a Gaussian form factor. It is found that for low and moderate values of magnetic field there is a decrease of the critical chiral restoration chemical potential ${\mu }_c$, i.e. an inverse magnetic catalysis effect is observed. For larger values of $eB$ the behavior of ${\mu }_c$ becomes more or less flat, depending on the parametrization. Within the considered parametrization range we do not find a significant growth of the critical chemical potential for large magnetic fields, as occurs in the case of the local NJL model.

    hep-phEPJA(2021)·8 citations
15. 15*

    Non-exclusive particle production by $\gamma \gamma$ interactions in $pp$ collisions at the LHC

    G. Gil da Silveira🇧🇷 · V. P. Goncalves🇧🇷 · G. G. Vargas Veronez🇧🇷

    Particle production in two-photon interactions at hadronic collisions is becoming increasingly relevant in the LHC physics programme as a way to improve our understanding of the Standard Model and search for signals of New Physics. A key ingredient for the study of these interactions in $pp$ collisions is the description of the photon content of the proton, which allow us to derive predictions for the cross sections associated to events where occur the proton dissociation (non - exclusive processes) and for those where both incident protons remain intact (exclusive processes). In this paper, a detailed comparison of the different models for the elastic and inelastic photon distributions found in the literature is presented and the current theoretical uncertainty is estimated. The impact on the invariant mass distribution for the dimuon production is analyzed. Moreover, the relative contribution of non - exclusive events is estimated and its dependence on the invariant mass of the pair is presented. We demonstrate that the predictions for production of pairs with large invariant mass is strongly dependent on the model assumed to describe the elastic and inelastic photon distributions and that the ratio between non - exclusive and exclusive cross sections present a mild energy dependence. Finally, our results indicate that a future experimental analysis of the non - exclusive events will be useful to constrain the photon content of proton.

    hep-phhep-exPRD(2021)·6 citations
16. 16*

    Transition distribution amplitudes and hard exclusive reactions with baryon number transfer

    B. Pire🇫🇷 · K. Semenov-Tian-Shansky🇷🇺 · L. Szymanowski🇵🇱

    Baryon-to-meson and baryon-to-photon transition distribution amplitudes (TDAs) arise in the collinear factorized description of a class of hard exclusive reactions characterized by the exchange of a non-zero baryon number in the cross channel. These TDAs extend the concepts of generalized parton distributions (GPDs) and baryon distribution amplitudes (DAs). In this review, we discuss the general properties and physical interpretation of baryon-to-meson and baryon-to-photon TDAs. We argue that these non-perturbative objects are a convenient complementary tool to explore the structure of baryons at the partonic level. We present an overview of hard exclusive reactions admitting a description in terms of TDAs. We discuss the first signals from hard exclusive backward meson electroproduction at JLab with the 6 GeV electron beam and explore further experimental opportunities to access TDAs at JLab@12 GeV, PANDA, J-PARC and EIC.

    hep-phhep-exnucl-thPhys.Rept.(2021)·37 citations
17. 17*

    Anomalies in $b\to s\ell \ell$ transitions and Global Fits

    Javier Virto🇪🇸

    We review the status of the anomalies in $b\to s\ell \ell$ transitions, and comment on the impact of the most recent measurements in 2019 and 2020 on the global fits. We also discuss a few developments in the theory calculation of local and non-local form factors.

    hep-phhep-exhep-latPoS(2021)·4 citations
18. 18*

    Emergent Hadrons and Diquarks

    Kenji Fukushima🇯🇵 · Jan M. Pawlowski🇩🇪 · Nils Strodthoff🇩🇪

    We discuss the emergence of a low-energy effective theory with quarks, mesons, diquarks and baryons at vanishing and finite baryon density from first principle QCD. The present work also includes an overview on diquarks at vanishing and finite density, and elucidates the physics of transitional changes from baryonic matter to quark matter including diquarks. This set-up is discussed within the functional renormalisation group approach with dynamical hadronisation. In this framework it is detailed how mesons, diquarks, and baryons emerge dynamically from the renormalisation flow of the QCD effective action. Moreover, the fundamental degrees of freedom of QCD, quarks and gluons, decouple from the dynamics of QCD below the respective mass gaps. The resulting global picture unifies the different low energy effective theories used for low and high densities within QCD, and allows for a determination of the respective low energy constants directly from QCD.

    hep-phhep-thnucl-thAnnals Phys.(2022)·42 citations
19. 19*

    Two-loop scalar functions with $I$ internal lines, $I\le 5$

    J. Ph. Guillet🇫🇷 · E. Pilon🇫🇷 · Y. Shimizu🇯🇵 · M. S. Zidi🇩🇿

    This article displays a proof of concept of the mixed analytical/numerical method, presented in previous publications, to compute two-loop functions with up to five massive propagators in a scalar theory having three- and four-leg vertices as the Higgs sector of the Standard Model. Several amplitudes are considered with two, three and four external legs. Some of them diverge in the UV region and we demonstrate that the method works in that case. It is shown that all these classes of amplitudes can be generated by four master topologies. Results of a numerical evaluation for some kinematics are presented, they are compared to a public code and agree well within the error bars quoted by the different programs.

    hep-phPTEP(2021)·0 citations
20. 20*

    Next-to-next-to-leading order event generation for $Z$ boson pair production matched to parton shower

    Simone Alioli🇮🇹 · Alessandro Broggio🇮🇹 · Alessandro Gavardi🇮🇹 · Stefan Kallweit🇮🇹 · Matthew A. Lim🇮🇹 · Riccardo Nagar🇮🇹 · Davide Napoletano🇮🇹

    We present a novel next-to-next-to-leading order (NNLO) QCD calculation matched to parton shower for the production of a pair of $Z$ bosons decaying to four massless leptons, $pp\to {\ell }^{+}{\ell }^{-}{\ell }^{\prime +}{\ell }^{\prime -}+X$, at the LHC. Spin correlations, interferences and off-shell effects are included throughout. Our result is based on the resummed beam-thrust spectrum, which we evaluate at next-to-next-to-leading-logarithmic (NNLL${}_{{\mathcal{T}}_0}^{\prime }$) accuracy for the first time for this process, and makes use of the GENEVA Monte Carlo framework for the matching to PYTHIA8 shower and hadronisation models. We compare our predictions with data from the ATLAS and CMS experiments at 13 TeV, finding a good agreement.

    hep-phhep-exPLB(2021)·44 citations
21. 21*

    Soft-gluon corrections for the associated production of a single top quark and a Higgs boson

    Matthew Forslund🇺🇸 · Nikolaos Kidonakis🇺🇸

    We discuss soft-gluon resummation for the associated production of a single top quark and a Higgs boson ($tqH$ production) in single-particle-inclusive (1PI) kinematics. We present analytical results for the higher-order corrections and numerical results for the cross sections at LHC energies. We calculate approximate NNLO total rates, including scale dependence and uncertainties from parton distributions, as well as top-quark transverse-momentum and rapidity distributions. In all cases we find that the soft-gluon corrections are dominant and provide important contributions to the total and differential cross sections.

    hep-phPRD(2021)·17 citations
22. 22*

    Robust Limits from Upcoming Neutrino Telescopes and Implications on Minimal Dark Matter Models

    S. Basegmez du Pree🇳🇱 · C. Arina🇧🇪 · A. Cheek🇧🇪 · A. Dekker🇳🇱 · M. Chianese🇮🇹 · S. Ando🇳🇱

    Experimental developments in neutrino telescopes are drastically improving their ability to constrain the annihilation cross-section of dark matter. In this paper, we employ an angular power spectrum analysis method to probe the galactic and extra-galactic dark matter signals with neutrino telescopes. We first derive projections for a next generation of neutrino telescope that is inspired by KM3NeT. We emphasise that such analysis is much less sensitive to the choice of dark matter density profile. Remarkably, the projected sensitivity is improved by more than an order of magnitude with respect to the existing limits obtained by assuming the Burkert dark matter density profile describing the galactic halo. Second, we analyse minimal extensions to the Standard Model that will be maximally probed by the next generation of neutrino telescopes. As benchmark scenarios, we consider Dirac dark matter in $s$- and $t$-channel models with vector and scalar mediators. We follow a global approach by examining all relevant complementary experimental constraints. We find that neutrino telescopes will be able to competitively probe significant portions of parameter space. Interestingly, the anomaly-free $L_{\mu }-L_{\tau }$ model can potentially be explored in regions where the relic abundance is achieved through freeze-out mechanism.

    hep-phastro-ph.COJCAP(2021)·14 citations
23. 23*

    Perturbative benchmark models for a dark shower search program

    Simon Knapen🇨🇭 · Jessie Shelton🇺🇸 · Dong Xu🇺🇸

    We provide five benchmark hidden valley models with perturbative parton showers, which span a wide range of dark shower phenomenology. We consider production through an $s$-channel, heavy mediator, which can be identified with the SM Higgs. By assuming a set of well-motivated decay portals, one can moreover fix both the branching ratios of the dark mesons and set a lower bound on their lifetime. We provide a public python tool which can be used to generate self-consistent PYTHIA 8 cards for our benchmark models.

    hep-phPRD(2021)·81 citations
24. 24*

    Spin polarization dynamics in the Bjorken-expanding resistive MHD background

    Rajeev Singh🇵🇱 · Masoud Shokri🇮🇷 · Radoslaw Ryblewski🇵🇱

    Evolution of spin polarization in the presence of external electric field is studied for collision energies $\sqrt{s_{\mathrm{NN}}}=27\mathrm{GeV}$ and $\sqrt{s_{\mathrm{NN}}}=200\mathrm{GeV}$. The numerical analysis is done in the perfect-fluid Bjorken-expanding resistive magnetohydrodynamic background and novel results are reported. In particular, we show that the electric field plays a significant role in the competition between expansion and dissipation.

    hep-phhep-thnucl-thPRD(2021)·29 citations
25. 25*

    Lepton Flavour Universality tests in electroweak penguin decays at LHCb

    Carla Marin Benito🇫🇷

    The coupling of the electroweak gauge bosons of the Standard Model (SM) to leptons is flavour universal. Extensions of the SM do not necessarily have this property. Rare decays of heavy flavour are suppressed in the SM and new particles may give sizeable contributions to these processes, therefore, their precise study allows for sensitive tests of lepton flavour universality. Of particular interest are rare b to sll decays that are well accessible at the LHCb experiment. Recent results from LHCb on lepton flavour universality in rare b to sll decays are discussed.

    ↳ hep-exhep-phPoS(2021)·0 citations
26. 26*

    Critical behavior of the 2d scalar theory: resumming the ${\mathrm{N}}^8\mathrm{LO}$ perturbative mass gap

    Gustavo O. Heymans🇧🇷 · Marcus Benghi Pinto🇧🇷

    We apply the optimized perturbation theory (OPT) to resum the perturbative series describing the mass gap of the bidimensional ${\varphi }^4$ theory in the ${\mathbb{Z}}_2$ symmetric phase. Already at NLO (one loop) the method is capable of generating a quite reasonable non-perturbative result for the critical coupling. At order-$g^7$ we obtain $g_c=2.779(25)$ which compares very well with the state of the art ${\mathrm{N}}^8\mathrm{LO}$ result, $g_c=2.807(34)$. As a novelty we investigate the supercritical region showing that it contains some useful complimentary information that can be used in extrapolations to arbitrarily high orders.

    ↳ hep-thcond-mat.otherhep-phJHEP(2021)·11 citations
27. 27*

    Multi-particle systems on the lattice and chiral extrapolations: a brief review

    Maxim Mai🇺🇸 · Michael Döring🇺🇸 · Akaki Rusetsky🇩🇪

    The extraction of two- and three-body hadronic scattering amplitudes and the properties of the low-lying hadronic resonances from the finite-volume energy levels in lattice QCD represents a rapidly developing field of research. The use of various modifications of the Lüscher finite-volume method has opened a path to calculate infinite-volume scattering amplitudes on the lattice. Many new results have been obtained recently for different two- and three-body scattering processes, including the extraction of resonance poles and their properties from lattice data. Such studies, however, require robust parametrizations of the infinite-volume scattering amplitudes, which rely on basic properties of $S$-matrix theory and -- preferably -- encompass systems with quark masses at and away from the physical point. Parametrizations of this kind, provided by unitarized Chiral Perturbation Theory, are discussed in this review. Special attention is paid to three-body systems on the lattice, owing to the rapidly growing interest in the field. Here, we briefly survey the formalism, chiral extrapolation, as well as finite-volume analyses of lattice data.

    ↳ hep-lathep-phnucl-thEur.Phys.J.ST(2021)·92 citations
28. 28*

    Topology change, emergent symmetries and compact star matter

    Yong-Liang Ma🇨🇳 · Mannque Rho🇫🇷

    Topology effects have being extensively studied and confirmed in strongly correlated condensed matter physics. In the large color number limit of QCD, baryons can be regarded as topological objects -- skyrmions -- and the baryonic matter can be regarded as a skyrmion matter. We review in this paper the generalized effective field theory for dense compact-star matter constructed with the robust inputs obtained from the skyrmion approach to dense nuclear matter, relying to possible ``emergent" scale and local flavor symmetries at high density. All nuclear matter properties from the saturation density $n_0$ up to several times $n_0$ can be fairly well described. A uniquely novel -- and unorthdox -- feature of this theory is the precocious appearance of the pseudo-conformal sound velocity $v_s^2/c^2\approx 1/3$, with the non-vanishing trace of the energy momentum tensor of the system. The topology change encoded in the density scaling of low energy constants is interpreted as the quark-hadron continuity in the sense of Cheshire Cat Principle (CCP) at density $\text{gsim}2n_0$ in accessing massive compact stars. We confront the approach with the data from GW170817 and GW190425.

    ↳ nucl-thastro-ph.HEhep-phAAPPS Bull.(2021)·19 citations
29. 29*

    High Energy Neutrinos from Choked Gamma-Ray Bursts in AGN Accretion Disks

    Jin-Ping Zhu🇨🇳 · Kai Wang🇨🇳 · Bing Zhang🇺🇸 · Yuan-Pei Yang🇨🇳 · Yun-Wei Yu🇨🇳 · He Gao🇨🇳

    Both long-duration gamma-ray bursts (LGRBs) from core collapse of massive stars and short-duration GRBs (SGRBs) from mergers of binary neutron star (BNS) or neutron star--black hole (NSBH) are expected to occur in the accretion disk of active galactic nuclei (AGNs). We show that GRB jets embedded in the migration traps of AGN disks are promised to be choked by the dense disk material. Efficient shock acceleration of cosmic rays at the reverse shock is expected, and high-energy neutrinos would be produced. We find that these sources can effectively produce detectable TeV--PeV neutrinos through $p\gamma$ interactions. From a choked LGRB jet with isotropic equivalent energy of $10^{53}\mathrm{erg}$ at $100\mathrm{Mpc}$, one expects $\sim 2(7)$ neutrino events detectable by IceCube (IceCube-Gen2). The contribution from choked LGRBs to the observed diffuse neutrino background depends on the unknown local event rate density of these GRBs in AGN disks. For example, if the local event rate density of choked LGRBs in AGN disk is $\sim 5\%$ that of low-luminosity GRBs $(\sim 10{\mathrm{Gpc}}^{-3}{\mathrm{yr}}^{-1})$, the neutrinos from these events would contribute to $\sim 10\%$ of the observed diffuse neutrino background. Choked SGRBs in AGN disks are potential sources for future joint electromagnetic, neutrino, and gravitational wave multi-messenger observations.

    ↳ astro-ph.HEastro-ph.GAastro-ph.SRhep-phApJL(2021)·34 citations
30. 30*

    Dilaton stabilization in KKLT revisited

    Min-Seok Seo🇰🇷

    We study the condition for the dilaton stabilization in Type IIB flux compactifications consistent with the KKLT scenario. Since the Gukov-Vafa-Witten superpotential depends linearly on the dilaton, the dilaton mass squared is given by a sum of the gravitino mass squared and additional terms determined by the complex structure moduli stabilization. If the dilaton mass is not much enhanced from the gravitino mass, the mass mixing with the Kähler modulus in the presence of the non-perturbative effect generates the saddle point at the supersymmetric field values, hence the potential becomes unstable. When the complex structure moduli other than the conifold modulus are neglected, the saddle point problem arises over the controllable parameter space. We also point out that the dilaton stabilization condition is equivalent to the condition on the NS 3-form fluxes, $|H_{(1,2)}|>|H_{(0,3)}|$.

    ↳ hep-thhep-phNPB(2021)·9 citations
31. 31*

    Superfluid stars and Q-balls in curved spacetime

    Konstantin G. Zloshchastiev🇿🇦

    Within the framework of the theory of strongly-interacting quantum Bose liquids, we consider a general relativistic model of self-interacting complex scalar fields with logarithmic nonlinearity taken from dense superfluid models. We demonstrate the existence of gravitational equilibria in this model, described by spherically symmetric nonsingular finite-mass asymptotically-flat solutions. These equilibrium configurations can describe both massive astronomical objects, such as bosonized superfluid stars or cores of neutron stars, and finite-size particles and non-topological solitons, such as Q-balls. We give an estimate for masses and sizes of such objects.

    ↳ astro-ph.HEgr-qchep-phLow Temp.Phys.(2021)·9 citations
32. 32*

    Study of the Standard Model with weak decays of charmed hadrons at BESIII

    Hai-Bo Li🇨🇳 · Xiao-Rui Lyu🇨🇳

    A comprehensive review of weak decays of charmed hadrons ($D^{0/+}$, $D_s^{+}$ and ${\Lambda }_c^{+}$) based on analyses of the threshold data from $e^{+}{e}^{-}$ annihilation in the BESIII experiment is presented. Current experimental challenges and successes in understanding decays of the charmed hadrons are discussed. Precise calibrations of QCD and tests of the Standard Model are provided by measurements of purely leptonic and semi-leptonic decays of charmed hadrons, and lepton universality is probed in purely leptonic decays of charmed mesons to three generations of leptons. Quantum correlations in threshold data samples provide access to strong phases in the neutral $D$ meson decays and probe the decay dynamics of the charmed ${\Lambda }_c$ baryon. Charm physics studies with near-threshold production of charmed particle pairs are unique to BESIII, and provide many important opportunities and challenges.

    ↳ hep-exhep-lathep-phNatl.Sci.Rev.(2021)·91 citations
33. 33*

    Pseudo-gauge dependence of quantum fluctuations of energy in a hot relativistic gas of fermions

    Arpan Das🇵🇱 · Wojciech Florkowski🇵🇱 · Radoslaw Ryblewski🇵🇱 · Rajeev Singh🇵🇱

    Explicit expressions for quantum fluctuations of energy in subsystems of a hot relativistic gas of spin-$1/2$ particles are derived. The results depend on the form of the energy-momentum tensor used in the calculations, which is a feature described as pseudo-gauge dependence. However, for sufficiently large subsystems the results obtained in different pseudo-gauges converge and agree with the canonical-ensemble formula known from statistical physics. As different forms of the energy-momentum tensor of a gas are a priori equivalent, our finding suggests that the concept of quantum fluctuations of energy in very small thermodynamic systems is pseudo-gauge dependent. On the practical side, the results of our calculations determine a scale of coarse graining for which the choice of the pseudo-gauge becomes irrelevant.

    ↳ nucl-thhep-phhep-thPRD(2021)·28 citations
34. 34*

    Complete ${\alpha }^{7}m$ Lamb shift of helium triplet states

    Vojtěch Patkóš🇨🇿 · Vladimir A. Yerokhin🇷🇺 · Krzysztof Pachucki🇵🇱

    We have derived the complete formula for the ${\alpha }^{7}m$ contribution to energy levels of an arbitrary triplet state of the helium atom, performed numerical calculations for the $2^{3}S$ and $2^{3}P$ states, and thus improved the theoretical accuracy of ionization energies of these states by more than an order of magnitude. Using the nuclear charge radius extracted from the muonic helium Lamb shift, we obtain the theoretical prediction in excellent agreement with the measured $2^{3}S-2^{3}P$ transition energy [X.~Zheng et al., Phys. Rev. Lett. {\bf 199}, 263002 (2017)]. At the same time we observe significant discrepancies with experiments for the $2^{3}S-3^{3}D$ and $2^{3}P-3^{3}D$ transitions.

    ↳ physics.atom-phhep-phPRA(2021)·45 citations
35. 35*

    Weakly bound $H$ dibaryon from SU(3)-flavor-symmetric QCD

    Jeremy R. Green🇨🇭 · Andrew D. Hanlon🇺🇸 · Parikshit M. Junnarkar🇩🇪 · Hartmut Wittig🇩🇪

    We present the first study of baryon-baryon interactions in the continuum limit of lattice QCD, finding unexpectedly large lattice artifacts. Specifically, we determine the binding energy of the $H$ dibaryon at a single quark-mass point. The calculation is performed at six values of the lattice spacing $a$, using O($a$)-improved Wilson fermions at the SU(3)-symmetric point with $m_{\pi }=m_K\approx 420$ MeV. Energy levels are extracted by applying a variational method to correlation matrices of bilocal two-baryon interpolating operators computed using the distillation technique. Our analysis employs Lüscher's finite-volume quantization condition to determine the scattering phase shifts from the spectrum and vice versa, both above and below the two-baryon threshold. We perform global fits to the lattice spectra using parametrizations of the phase shift, supplemented by terms describing discretization effects, then extrapolate the lattice spacing to zero. The phase shift and the binding energy determined from it are found to be strongly affected by lattice artifacts. Our estimate of the binding energy in the continuum limit of three-flavor QCD is $B_H^{{\text{SU(3)}}_{\mathrm{f}}}=4.56\pm 1.13_{\mathrm{stat}}\pm 0.63_{\mathrm{syst}}$ MeV.

    ↳ hep-lathep-phnucl-thPRL(2021)·139 citations
36. 36*

    In the Realm of the Hubble tension $-$ a Review of Solutions

    Eleonora Di Valentino🇬🇧 · Olga Mena🇪🇸 · Supriya Pan🇮🇳 · Luca Visinelli🇮🇹 · Weiqiang Yang🇨🇳 · Alessandro Melchiorri🇮🇹 · David F. Mota🇳🇴 · Adam G. Riess🇺🇸 · Joseph Silk🇫🇷

    The $\Lambda$CDM model provides a good fit to a large span of cosmological data but harbors areas of phenomenology. With the improvement of the number and the accuracy of observations, discrepancies among key cosmological parameters of the model have emerged. The most statistically significant tension is the $4-6\sigma$ disagreement between predictions of the Hubble constant $H_0$ by early time probes with $\Lambda$CDM model, and a number of late time, model-independent determinations of $H_0$ from local measurements of distances and redshifts. The high precision and consistency of the data at both ends present strong challenges to the possible solution space and demand a hypothesis with enough rigor to explain multiple observations--whether these invoke new physics, unexpected large-scale structures or multiple, unrelated errors. We present a thorough review of the problem, including a discussion of recent Hubble constant estimates and a summary of the proposed theoretical solutions. Some of the models presented are formally successful, improving the fit to the data in light of their additional degrees of freedom, restoring agreement within $1-2\sigma$ between {\it Planck} 2018, using CMB power spectra data, BAO, Pantheon SN data, and R20, the latest SH0ES Team measurement of the Hubble constant ($H_0=73.2\pm 1.3\mathrm{km}{\mathrm{s}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-1}$ at 68\% confidence level). Reduced tension might not simply come from a change in $H_0$ but also from an increase in its uncertainty due to degeneracy with additional physics, pointing to the need for additional probes. While no specific proposal makes a strong case for being highly likely or far better than all others, solutions involving early or dynamical dark energy, neutrino interactions, interacting cosmologies, primordial magnetic fields, and modified gravity provide the best options until a better alternative comes along.[Abridged]

    ↳ astro-ph.COastro-ph.GAgr-qchep-phClass.Quant.Grav.(2021)·2518 citations
37. 37*

    On chiral vortical effect in accelerated matter

    P.G. Mitkin🇷🇺 · V.I. Zakharov🇷🇺

    We revisit the evaluation of the chiral vortical effect in the accelerated matter. To first order in the acceleration the corresponding matrix element of the axial current can be reconstructed from the flat-space limit. A crucial point is the existence in the this case of an extra conservation law of fluid helicity. As a result, the chirality of the microscopic degrees of freedom and helicity of the macroscopic motion are separately conserved. This separation persists also in presence of gravity. Implications for the thermal chiral vortical effect are discussed.

    ↳ hep-thhep-phPRD(2021)·4 citations
38. 38*

    Precise and Accurate Cosmology with CMBxLSS Power Spectra and Bispectra

    Shu-Fan Chen🇺🇸 · Hayden Lee🇺🇸 · Cora Dvorkin🇺🇸

    With the advent of a new generation of cosmological experiments that will provide high-precision measurements of the cosmic microwave background (CMB) and galaxies in the large-scale structure, it is pertinent to examine the potential of performing a joint analysis of multiple cosmological probes. In this paper, we study the cosmological information content contained in the one-loop power spectra and tree bispectra of galaxies cross-correlated with CMB lensing. We use the FFTLog method to compute angular correlations in spherical harmonic space, applicable for wide angles that can be accessed by forthcoming galaxy surveys. We find that adding the bispectra and cross-correlations with CMB lensing offers a significant improvement in parameter constraints, including those on the total neutrino mass, $M_{\nu }$, and local non-Gaussianity amplitude, $f_{\mathrm{NL}}$. In particular, our results suggest that the combination of the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST) and CMB-S4 will be able to achieve $\sigma (M_{\nu })=42$ meV from galaxy and CMB lensing correlations, and $\sigma (M_{\nu })=12$ meV when further combined with the CMB temperature and polarization data, without any prior on the optical depth.

    ↳ astro-ph.COhep-phJCAP(2021)·43 citations
39. 39*

    Hidden Symmetry of Vanishing Love

    Panagiotis Charalambous🇺🇸 · Sergei Dubovsky🇺🇸 · Mikhail M. Ivanov🇺🇸

    We show that perturbations of massless fields in the Kerr black hole background enjoy a hidden $SL(2,\mathbb{R})\times U(1)$ ("Love") symmetry in the properly defined near zone approximation. Love symmetry mixes IR and UV modes. Still, this approximate symmetry allows us to derive exact results about static tidal responses. Generators of the Love symmetry are globally well defined and have a smooth Schwarzschild limit. Generic regular solutions of the near zone Teukolsky equation form infinite-dimensional $SL(2,\mathbb{R})$ representations. In some special cases ($\hat{\ell }$ parameter is an integer), these are highest weight representations. This is the situation that corresponds to vanishing Love numbers. In particular, static perturbations of four-dimensional Schwarzschild black holes belong to finite-dimensional representations. Other known facts about static Love numbers also acquire an elegant explanation in terms of the $SL(2,\mathbb{R})$ representation theory.

    ↳ hep-thastro-ph.HEgr-qchep-phPRL(2021)·149 citations
40. 40*

    Motion of classical charged particles with magnetic moment in external plane-wave electromagnetic fields

    Martin Formanek🇺🇸 · Andrew Steinmetz🇺🇸 · Johann Rafelski🇺🇸

    We study the motion of a charged particle with magnetic moment in external electromagnetic fields utilizing covariant unification of Gilbertian and Amperian descriptions of particle magnetic dipole moment. Considering the case of a current loop, our approach is verified by comparing classical dynamics with the classical limit of relativistic quantum dynamics. We obtain motion of a charged particle in the presence of an external linearly polarized EM (laser) plane wave field incorporating the effect of spin dynamics. For specific laser-particle initial configurations, we determine that the Stern-Gerlach force can have a cumulative effect on the trajectory of charged particles.

    ↳ physics.class-phhep-phPRA(2021)·6 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.