Tue·May 3, 2022Tuesday·May 3, 2022

1. 01*

   Physics at Future Colliders: the Interplay Between Energy and Luminosity

   Zhen Liu🇺🇸 · Lian-Tao Wang🇺🇸

   In this note, as an input to the Snowmass studies, we provide a broad-brush picture of the physics output of future colliders as a function of their center of mass energies and luminosities. Instead of relying on precise projections of physics reaches, which are lacking in many cases, we mainly focused on simple benchmarks of physics yields, such as the number of Higgs boson produced. More detailed considerations for lepton colliders are given since there have been various recent proposals. A brief summary for hadron colliders based on a simple scaling estimate of the physics reaches is also included.

   hep-phhep-ex5 citations
2. 02*

   Challenges to Obtaining Results for Real QCD from SUSY QCD

   Michael Dine🇺🇸 · Yan Yu🇺🇸

   Recently there have been proposals to understand features of QCD such as confinement and chiral symmetry breaking by considering supersymmetric versions of the theory with various patterns of soft breaking. In this note we recall that with small soft breakings, SUSY QCD is suggestive of observed features of real QCD. But we outline some of the challenges to establishing these features of the theory with large soft breakings. It appears difficult to argue for confinement or chiral symmetry breaking; at best, one can say that {\it if} the non-supersymmetric theory does not confine and/or break chiral symmetry, phase transitions would appear inevitable as one increases the soft breakings. We also discuss, at large N, where confinement would imply chiral symmetry breaking, the challenges to establishing confinement.

   hep-phhep-th12 citations
3. 03*

   A CT18 global PDF fit at the leading order in QCD

   Mengshi Yan🇨🇳 · Tie-Jiun Hou🇨🇳 · Pavel Nadolsky🇺🇸 · C.-P. Yuan🇺🇸

   In this paper, we present a CT18 PDFs fitted with Leading-Order QCD perturbation theory. The CT18 LO PDFs is obtained within the general CT18 framework, along with two additional treatments being imposed to improve the quality of the fit. We take the $W$-boson charge asymmetry and inclusive single-top production at LHC as examples to illustrate the implication of the CT18 LO PDFs.

   hep-phPRD(2023)·24 citations
4. 04*

   Investigating non-minimal flavour-violating CMSSM in the light of Higgs-Boson mass using information theory

   Surabhi Gupta🇮🇳 · Sudhir Kumar Gupta🇮🇳

   Flavour-violating interactions of the stop-quarks are expected to provide an additional few GeV contributions to the Higgs-Boson mass, particularly when mix with scharm-quarks, thereby allowing reduced supersymmetry (SUSY) breaking scale compared to flavour-conserving constrained minimal supersymmetric Standard Model (CMSSM). Inspired by this, we analyse the interactions mentioned above in the context of CMSSM using the information entropy of the Higgs-Boson for a wider region of flavour-violating CMSSM parameter space $(m_0,m_{1/2},A_0,$ $\tan \beta ,sgn(\mu ),{\delta }_{ct}^{ij})$, where ${\delta }_{ct}^{ij}$ represents the flavour-violating coupling of the top-quark with the charm-quark and $i,j$ defining left and right chiralities of squarks. Our information-theoretic analysis of the model mentioned above reveals the most favourable values of $(m_0,m_{1/2},A_0,\tan \beta ,{\delta }_{ct}^{ij})$ as $(4.30\mathrm{TeV},2.32\mathrm{TeV},-4.96\mathrm{TeV},$ $22.8,0.037)$ and $(4.16\mathrm{TeV},$ $3.89\mathrm{TeV},-4.10\mathrm{TeV},19.4,0.039)$ for $(i,j)=(L,R)$ and $(R,L)$, respectively, corresponding to the maximum entropy which suggest the SUSY breaking scale to be about $5$ TeV, thereby allowing considerable low values of sparticles masses than the flavour-conserving CMSSM.

   hep-phhep-exhep-thNPB(2022)·3 citations
5. 05*

   WKB approximation under Killingbeck potential and its application to double heavy meson mass spectrum

   Lhamo chosto🇨🇳 · Ya-rong Wang🇨🇳 · Zhi-bin Gao🇨🇳 · Cheng-qun Pang🇨🇳 · Hao Chen🇨🇳 · Yu-Long Kang🇨🇳

   As we all known that non-relativistic or semi-relativistic constituent quark models can describe a large number of the meson sand baryon properties with surprising accuracy. In this work, we studied Killingbeck potential by using WKB approximation in the constituent quark model. The implicit approximate solution of the energy eigenvalue of the Schrödinger equation is obtained by using appropriate quantization conditions. Under the Killingbeck potential with the WKB approximation, we studied the spectra of double heavy mesons and predict the masses of high excited states in $c\bar{c}$, $b\bar{b}$ and $b\bar{c}$ families. Finally, we discuss the application scope of double heavy mesons in Killingbeck potential.

   hep-ph0 citations
6. 06*

   Dark matter properties from the Fornax globular cluster timing: dynamical friction and cored profiles

   D. Blas🇪🇸

   I summarize our recent results to use the orbits of globular clusters (GCs) in the Fornax dwarf spheroidal (dSph) galaxy to learn more about dark matter (DM) properties. Our focus is on clarifying how dynamical friction (DF) from the DM halo is modified from the different microscopic properties of DM, which may alter $both$ the scattering processes responsible of DF and the DM profiles (in particular generating a core), which also modifies DF. We consider: $(i)$ fermionic degenerate dark matter (DDM), where Pauli blocking should be taken into account in the dynamical friction computation; $(ii)$ self-interacting dark matter (SIDM) and $(iii)$ ultralight dark matter (ULDM), for which this problem has been addressed by a variety of methods in recent literature. We derive DF with a Fokker-Planck formalism, reproducing previous results for ULDM and cold DM, while providing new results for DDM. Furthermore, ULDM, DDM and SIDM may generate cores in dSphs, which suppress dynamical friction and prolong GC orbits. We conclude that in all these cases the modifications in the DM modelling does not easily solve the so-called timing `problem' of Fornax GCs. We finally study this `problem' in terms of the initial conditions, demonstrating that the observed orbits of Fornax GCs are consistent with this expectation of a cuspy DM profile with a mild `fine-tuning' at the level of $\sim 25\%$.

   hep-phastro-ph.GA3 citations
7. 07*

   Transport coefficients in thermal QCD: A probe to the collision integral

   Salman Ahamad Khan🇮🇳 · Binoy Krishna Patra🇮🇳

   We have studied the transport coefficients as a tool to probe the collision integral appeared in the Boltzmann equation. For this purpose, we have estimated the transport coefficients (momentum: \{$\eta$,$\zeta$\}, heat: \{$\kappa$\}, and charge: \{${\sigma }_{\mathrm{el}}$\}) in the kinetic theory with Bhatnagar-Gross-Krook (BGK) and the collision integral in RTA and ask whether we can distinguish between the two collision integrals. For example, $\eta$ gets enhanced while $\zeta$ gets reduced w.r.t. to RTA. As a corollary, we then investigate the interplay among the aforesaid transport coefficients, {\em viz.} fluidity and transition point of QCD medium by evaluating the ratios, $\eta /s$ and $\zeta /s$, respectively, nature of flow (Reynolds number, RI), sound attenuation (Prandtl number, Pr), and competition between the momentum and charge diffusion ($\gamma$) etc. as further plausible tools to decipher the same. With BGK collision integral, the ratios, $\eta /s$ (increase) and $\zeta /s$ (decrease) shows opposite behavior whereas Pr, RI, $\gamma$ and the ratio $\zeta /\eta$ get reduced w.r.t RTA. We then examine how a strong $B$ modulate the impact of collision integral, which, in a way, explore the dimensionality dependence of the momentum transport because the quark dynamics gets restricted to 1-D only and only the lowest Landau levels are populated. As a result, $\eta$ ($\zeta$) gets reduced (amplified), which will have ramifications on the ratios, {\em viz.} $\eta /s$ ($\zeta /s$) becomes smaller (larger), enhancement of Pr, $\gamma$ and $\zeta /\eta$ etc. In this study, the thermo-magnetic medium effects have been incorporated by adopting a quasi-particle model, where the medium generated masses of the partons have been obtained from the pole of their resummed propagators calculated using perturbative thermal QCD in strong $B$.

   hep-phPRD(2022)·11 citations
8. 08*

   LHC phenomenology of unusual top partners in composite Higgs models

   Werner Porod🇩🇪

   Composite Higgs models with a fermionic UV completion can contain additional colored states beside the usual top-partners. We focus here on a model which contains in addition SU(3) color octet top partners as well as color singlet ones. The latter can in principle serve as a dark matter candidate. We consider a particular composite Higgs model which contains SU(3) color octet top partners besides the usually considered triplet representations. Moreover, color singlet top partners are present as well which can in principle serve as dark matter candidates. We investigate the LHC phenomenology of these unusual top partners. Some of these states could at first glance be confused with gluinos predicted in supersymmetric models.

   hep-phPoS(2022)·0 citations
9. 09*

   Promises and challenges of high-energy vortex states collisions

   Igor P. Ivanov🇨🇳

   Vortex states of photons, electrons, and other particles are non--plane-wave solutions of the corresponding wave equation with helicoidal wave fronts. These states possess an intrinsic orbital angular momentum with respect to the average propagation direction, which represents a new degree of freedom, previously unexplored in particle or nuclear collisions. Vortex states of photons, electrons, neutrons, and neutral atoms have been experimentally produced, albeit at low energies, and are being intensively explored. Anticipating future experimental progress, one can ask what additional insights on nuclei and particles one can gain once collisions of high-energy vortex states become possible. This review describes the present-day landscape of physics opportunities, experimental progress and suggestions relevant to vortex states in high energy collisions. The aim is to familiarize the community with this emergent cross-disciplinary topic and to provide a sufficiently complete literature coverage, highlighting some results and calculational techniques.

   hep-phhep-exphysics.acc-phPPNP(2022)·87 citations
10. 10*

    QCD at finite temperature and density within the fRG approach: An overview

    Wei-jie Fu🇨🇳

    In this paper we present an overview on recent progress in studies of QCD at finite temperature and densities within the functional renormalization group (fRG) approach. The fRG is a nonperturbative continuum field approach, in which quantum, thermal and density fluctuations are integrated in successively with the evolution of the renormalization group (RG) scale. The fRG results for the QCD phase structure and the location of the critical end point (CEP), the QCD equation of state (EoS), the magnetic EoS, baryon number fluctuations confronted with recent experimental measurements, various critical exponents, spectral functions in the critical region, the dynamical critical exponent, etc., are presented. Recent estimates of the location of the CEP from first-principle QCD calculations within fRG and Dyson-Schwinger Equations, which passes through lattice benchmark tests at small baryon chemical potentials, converge in a rather small region at baryon chemical potentials of about 600 MeV. A region of inhomogeneous instability indicated by a negative wave function renormalization is found with ${\mu }_B\gtrsim 420$ MeV. It is found that the non-monotonic dependence of the kurtosis of the net-proton number distributions on the beam collision energy observed in experiments, could arise from the increasingly sharp crossover in the regime of low collision energy.

    hep-phnucl-exnucl-thCommun.Theor.Phys.(2022)·126 citations
11. 11*

    Improved tests of entanglement and Bell inequalities with LHC tops

    J. A. Aguilar-Saavedra🇪🇸 · J. A. Casas🇪🇸

    We discuss quantum entanglement in top pair production at the LHC. Near the $t\bar{t}$ threshold, entanglement observables are enhanced by suppressing the contribution of $q\bar{q}$ subprocesses, which is achieved by a simple cut on the velocity of the $t\bar{t}$ system in the laboratory frame. Furthermore, we design new observables that directly measure the relevant combinations of $t\bar{t}$ spin correlation coefficients involved in the measurement of entanglement and Bell inequalities. As a result, the statistical sensitivity is enhanced, up to a factor of 7 for Bell inequalities near threshold.

    hep-phhep-exEPJC(2022)·156 citations
12. 12*

    Thermalization by off-shell processes: the virtues of small virtuality

    Daniel Boyanovsky🇺🇸

    We study the thermalization of a scalar field $\Phi$ coupled to two other scalar fields ${\chi }_{1,2}$ that constitute a bath in thermal equilibrium. For a range of masses the $\Phi$ propagator features threshold and infrared divergences, a vanishing residue at the (quasi) particle pole and vanishing \emph{on-shell} decay rates thereby preventing the equilibration of $\Phi$ with the bath via on-shell processes. Inspired by the theory of quantum open systems we obtain a quantum master equation for the reduced density matrix of $\Phi$ that includes the time dependence of bath correlations, yielding time dependent rates in the dynamics of relaxation and allowing virtual processes of small virtuality $\propto 1/t$ at long time $t$. These \emph{off-shell} processes lead to thermalization despite vanishing S-matrix rates. In the case of threshold divergences we find that a thermal fixed point is approached as $e^{-\sqrt{t/t^{\ast }}}$ with the relaxation time $t^{\ast }$ becoming shorter at high temperature as a consequence of stimulated emission and absorption. In the infrared case, the thermal fixed point is approached as $e^{-\gamma (t)}$, where $\gamma (t)$ features a crossover between a $\propto \ln (t)$ and a $\propto t$ behavior for $t\gg 1/T$. The vanishing of the residue and the crossover in relaxational dynamics in this case is strikingly reminiscent of the orthogonality catastrophe in heavy impurity systems. The results yield more general lessons on thermalization via virtual processes.

    hep-phcond-mat.otherhep-thquant-phPRD(2022)·3 citations
13. 13*

    Mass-spectra of light-heavy tetraquarks

    Rohit Tiwari🇮🇳 · Juhi Oudichhya🇮🇳 · Ajay Kumar Rai🇮🇳

    The mass spectra of light-heavy tetraquarks $cq\bar{c}\bar{q}$ (q= u, d) are computed in a non-relativistic diquark model with one-gluon exchange plus confining potential. In the diquark model, a $cq\bar{c}\bar{q}$ state is regarded to be made of a light-heavy diquark (qc) and an antidiquark $\bar{q}\bar{c}$ in triplet and antitriplet colour configuration respectively. The masses of charm mesons were calculated in order to fit the model parameters used to create the masses of tetraquarks and therefore enhance the model's reliability. The masses of $(cq\bar{c}\bar{q})$ tetra-quark states are determined to be in the range of 3.8 GeV - 4.7 GeV, which is consistent with the experimentally reported charmonium-like states. In particular, the $Z_c(3900)$, $Z_c(4430)$, and $\psi (4660)$ tetraquarks, which have been seen experimentally, may all be described by our model.

    hep-phInt.J.Mod.Phys.A(2023)·7 citations
14. 14*

    Regarding the possibility to observe the LHCb hidden-charm strange pentaquark $P_{cs}(4459{)}^0$ in antikaon-induced $J/\psi$ meson production on protons and nuclei near the $J/\psi$$\Lambda$ production threshold

    E. Ya. Paryev🇷🇺

    We study the near-threshold $J/\psi$ meson production on protons and nuclei by considering incoherent direct non-resonant $K^{-}p\to J/\psi \Lambda$ and two-step resonant $K^{-}p\to P_{cs}(4459{)}^0\to J/\psi \Lambda$ charmonium production processes. We calculate the absolute excitation functions, energy and momentum distributions for the non-resonant, resonant and for the combined (non-resonant plus resonant) production of $J/\psi$ mesons off protons as well as off carbon and tungsten target nuclei at near-threshold incident antikaon energies by considering these elementary production channels as well as by assuming the spin-parity assignment of the hidden-charm resonance $P_{cs}(4459{)}^0$ with strangeness as $J^P=(3/2{)}^{-}$ within six different scenarios for the branching ratio $Br[P_{cs}(4459{)}^0\to J/\psi \Lambda ]$ of the decay $P_{cs}(4459{)}^0\to J/\psi \Lambda$. We show that the combined observables considered reveal definite sensitivity to these scenarios, which means that they may be an important tool to provide further evidence for the existence of the pentaquark $P_{cs}(4459{)}^0$ resonance and to get valuable information on its decay rate to the $J/\psi \Lambda$ final state. Their measurements could be performed in the future at the J-PARC Hadron Experimental Facility.

    hep-phnucl-exnucl-thNPA(2022)·6 citations
15. 15*

    Sterile neutrinos, $0\nu \beta \beta$ decay and the W-boson mass anomaly in a Flipped $SU(5)$ from F-theory

    Vasileios Basiouris🇬🇷 · George K. Leontaris🇬🇷

    We investigate the low energy properties of an effective local model with flipped $SU(5)\times U(1{)}_{\chi }$ gauge group, constructed within the framework of F-theory. Its origin is traced back to the $SO(10)$ symmetry -- associated with a geometric singularity of the compactification manifold -- broken by an internal flux which is turned on along the seven-brane in the $U(1{)}_{\chi }$ direction. Topological properties and the choice of flux parameters determine the massless spectrum of the model to be that of the minimal flipped $SU(5)$ supplemented with an extra right-handed electron-type state and its complex conjugate, $E^c+{\bar{E}}^c$, as well as neutral singlet fields. The subsequent symmetry breaking to the $SU(3)\times SU(2)\times U(1{)}_Y$ gauge group occurs with a Higgs pair in $10+\overline{10}$ representations of $SU(5)$. Next we proceed to the phenomenological analysis of the resulting effective model and the salient outcomes are: The $E^c+{\bar{E}}^c$ pair acquires a mass of few TeV and as such could solve the $g_{\mu }-2$ discrepancy. Neutrino couplings to extra neutral singlets lead to an inverse seesaw mechanism where an extra light state could be a suitable dark matter candidate. The predictions of the model for the $0\nu \beta \beta$ decay rate could be tested in near future experiments. There are non-unitarity deviations from lepton mixing matrix ($U_{PMNS}$), which could in principle explain the new precision measurement of the W-boson mass recently reported by CDF II collaboration.

    hep-phhep-exhep-thEPJC(2022)·15 citations
16. 16*

    Investigating Two-zero Textures of Inverse Neutrino Mass Matrix under the Lamp Post of LMA and LMA-D Solutions and Symmetry Realization

    Labh Singh🇮🇳 · Monal Kashav🇮🇳 · Surender Verma🇮🇳

    In this work we have investigated the phenomenological consequences of two-zero textures of \textit{inverse} neutrino mass matrix ($M_{\nu }^{-1}$) in light of the large mixing angle (LMA) and large mixing angle-\textit{dark} (LMA-D) solutions, later of which originates if neutrinos exhibit non-standard interactions with matter. Out of fifteen possibilities, only seven two-zero textures of $M_{\nu }^{-1}$ are found to be phenomenologically allowed under LMA and/or LMA-D descriptions. In particular, five textures are in consonance with both LMA and LMA-D solutions and are necessarily $CP$ violating while remaining two textures are found to be consistent with LMA solution only. The textures with vanishing (1, 1) element of $M_{\nu }^{-1}$ are, in general, disallowed. All the textures allowed under LMA and LMA-D solutions follow the same neutrino mass hierarchy. Furthermore, textures with vanishing (2, 3) element of $M_{\nu }^{-1}$ are found to be either disallowed or are consistent with LMA description only. We have, also, obtained the implication of the model for $0\nu \beta \beta$ decay amplitude $|M_{ee}|$. For most of the textures the calculated $3\sigma$ lower bound on $|M_{ee}|$ is $\mathcal{O}(10^{-2})$, which is within the sensitivity reach of $0\nu \beta \beta$ decay experiments. We have, also, proposed a flavor model based on discrete non-Abelian flavor group $A_4$ wherein such textures of $M_{\nu }^{-1}$ can be realized within Type-I seesaw setting.

    hep-phEPJC(2022)·10 citations
17. 17*

    Electroweak dark matter model accounting for the CDF $W$-mass anomaly

    Jin-Wei Wang🇮🇹 · Xiao-Jun Bi🇨🇳 · Peng-Fei Yin🇨🇳 · Zhao-Huan Yu🇨🇳

    Recently, the CDF collaboration reported a new measurement of the $W$ boson mass $M_W=80.4335\pm 0.0094$ GeV, which shows a $\sim 7\sigma$ deviation from the standard model prediction $80.3545\pm 0.0057$ GeV obtained by the electroweak (EW) global fit. This deviation can be explained by new physics generating moderate EW oblique parameters $S$, $T$, and $U$. In this work, we use the loop corrections induced by some extra EW multiplets to explain the CDF $M_W$ anomaly. The lightest neutral particle in the multiplets can also serve as a candidate of cold dark matter (DM). We consider two such models, namely singlet-triplet scalar DM and singlet-doublet fermionic DM models, and perform numerical scans to find the parameter points accounting for the $M_W$ anomaly. The constraints from the correct DM thermal relic density and direct detection are also taken into account. We find the parameter points simultaneously interpreting the $M_W$ anomaly and satisfying the DM requirements in the former model, but do not find such parameter points in the latter model.

    hep-phPRD(2022)·37 citations
18. 18*

    Distinguishing Dirac vs. Majorana Neutrinos: a Cosmological Probe

    Beatriz Hernandez-Molinero🇪🇸 · Raul Jimenez🇪🇸 · Carlos Pena-Garay🇪🇸

    Cosmic background neutrinos ($C_{\nu }B)$ helicity composition is different for Dirac or Majorana neutrinos making detectors based on $C_{\nu }B$ capture sensitive to the nature of neutrinos. We calculate, for the first time, the helicity changes of neutrinos crossing dark matter fields, to quantitatively calculate this effect on the capture rate. We show that a fraction of neutrinos change their helicity, regardless of them being deflected by a void or a dark matter halo. The average signal from the 100 most massive voids or halos in a Gpc${}^3$ gives a prediction that if neutrinos are Dirac, the density of the $C_{\nu }B$ background measured on Earth should be 48 cm${}^{-3}$ for left-helical neutrinos, a decrease of 15% (53.6 cm${}^{-3}$; 5%) for a halo (void) with respect to the standard calculation without including gravitational effects due to large scale structures. In terms of the total capture rate in a 100 g tritium detector, this translates in $4.9_{-0.8}^{+1.1}$ neutrinos per year for the Dirac case, as a function of the unknown neutrino mass scale, or 8.1 per year if neutrinos are Majorana. Thus although smaller than the factor two for the non-relativistic case, it is still large enough to be detected and it highlights the power of future $C_{\nu }B$ detectors, as an alternative to neutrinoless double beta decay experiments, to discover the neutrino nature.

    hep-phastro-ph.COJCAP(2022)·18 citations
19. 19*

    The electromagnetic Sigma-to-Lambda transition form factors with coupled-channel effects in the space-like region

    Yong-Hui Lin🇩🇪 · Hans-Werner Hammer🇩🇪 · Ulf-G. Meißner🇩🇪

    Using dispersion theory, the electromagnetic Sigma-to-Lambda transition form factors are expressed as the product of the pion electromagnetic form factor and the $\Sigma \bar{\Lambda }\to \pi \pi$ scattering amplitudes with the latter estimated from SU(3) chiral perturbation theory including the baryon decuplet as explicit degrees of freedom. The contribution of the $K\bar{K}$ channel is also taken into account and the $\pi \pi$-$K\bar{K}$ coupled-channel effect is included by means of a two-channel Muskhelishvili-Omnès representation. It is found that the electric transition form factor shows a significant shift after the inclusion of the $K\bar{K}$ channel, while the magnetic transition form factor is only weakly affected. However, the $K\bar{K}$ effect on the electric form factor is obscured by the undetermined coupling $h_A$ in the three-flavor chiral Lagrangian. The error bands of the Sigma-to-Lambda transition form factors from the uncertainties of the couplings and low-energy constant in three-flavor chiral perturbation theory are estimated by a bootstrap sampling method.

    hep-phhep-exnucl-exnucl-thEPJA(2023)·11 citations
20. 20*

    EFT Diagrammatica II: Tracing the UV origin of bosonic D6 CPV and D8 SMEFT operators

    Wrishik Naskar🇮🇳 · Suraj Prakash🇮🇳 · Shakeel Ur Rahaman🇮🇳

    In recent times, SMEFT, along with a superlative repertoire of theoretical and computational tools, has emerged as an efficacious platform to test the viability of proposed BSM scenarios. With symmetry as the backbone, higher mass dimensional ($\ge 5$) SMEFT operators constitute the \textit{lingua franca} for studying and comparing the direct or indirect effects of UV models on low energy observables. The steady increase in the accessible energy scales for contemporary particle collision experiments prompts us to inspect effective operators beyond the leading order and investigate their measurable impact as well as their connections with the appropriate BSM proposals. We take the next step in delineating the possible UV roots of SMEFT operators by extending our diagrammatic approach, previously employed for CP, baryon, and lepton number conserving dimension-6 operators, to the complete set of purely bosonic SMEFT operators up to mass dimension-8. We catalogue a diverse array of Feynman diagrams elucidating how the operators encapsulate heavy field propagators while abiding by a notion of minimalism.

    hep-phhep-thJHEP(2022)·21 citations
21. 21*

    $D$-meson production in high energy $pA$ collisions within the QCD color dipole transverse momentum representation

    G. Sampaio dos Santos🇧🇷 · G. Gil da Silveira🇧🇷 · M. V. T. Machado🇧🇷

    The $D$-meson production is investigated by considering the unintegrated gluon distribution within the dipole approach in the momentum representation. We analyze the $D$-meson spectrum accounting for the effects of nonlinear behavior of the QCD dynamics which can be accordingly addressed in the dipole framework. The unintegrated gluon distribution is obtained by using geometric scaling property and the results are compared to the Glauber-Gribov framework. The absolute transverse momentum spectra and the nuclear modification ratios are investigated. Predictions are compared with the experimental measurements by the ALICE and LHCb Collaborations in $pA$ collisions for different rapidity bins.

    hep-phhep-exEPJC(2022)·7 citations
22. 22*

    Axion-like Particles Implications for High-Energy Astrophysics

    Giorgio Galanti🇮🇹 · Marco Roncadelli🇮🇹

    We offer a pedagogical introduction to axion-like particles (ALPs) as far as their relevance for high-energy astrophysics is concerned, from a few MeV to 1000 TeV. This review is self-contained, in such a way to be understandable even to non-specialists. Among other things, we discuss two strong hints at a specific ALP that emerge from two very different astrophysical situations. More technical matters are contained in three Appendices.

    hep-phastro-ph.HEhep-thUniverse(2022)·56 citations
23. 23*

    Charge transfer between rotating complex scalar fields

    Valerie Domcke🇨🇭 · Keisuke Harigaya🇨🇭 · Kyohei Mukaida🇯🇵

    We consider the transfer of a U(1) charge density between Bose-Einstein condensates of complex scalar fields coupled to a thermal bath, focusing on the case of a homogeneous Affleck-Dine field transmitting the charge stored in its angular motion to an axion field. We demonstrate that in the absence of additional symmetries this charge transfer, aided by cosmic expansion as well as the thermal effective potential of the Affleck-Dine field, can be very efficient. The charge redistribution between the scalar fields becomes possible if the interactions with the thermal bath break the original U(1) x U(1) symmetry down to a single U(1) symmetry; the charge distribution between the two fields is then determined by minimizing the free energy. We discuss implications for cosmological setups involving complex scalars, with applications to axion dark matter, baryogenesis, kination domination, and gravitational wave production.

    hep-phastro-ph.COJHEP(2022)·20 citations
24. 24*

    Updated QCD global analysis of single transverse-spin asymmetries I: Extracting $\tilde{H}$, and the role of the Soffer bound and lattice QCD

    Leonard Gamberg🇺🇸 · Michel Malda🇺🇸 · Joshua A. Miller🇺🇸 · Daniel Pitonyak🇺🇸 · Alexei Prokudin🇺🇸 · Nobuo Sato🇺🇸

    We present an update to the QCD global analysis of single transverse-spin asymmetries presented in Cammarota, et al., PRD 102, 054002 (2020) (JAM3D-20). JAM3D-20 simultaneously included transverse momentum dependent and collinear twist-3 observables, both of which are sensitive to quark-gluon-quark correlations in hadrons. In this study we extract for the first time the twist-3 chiral odd fragmentation function $\tilde{H}$ by incorporating the $\sin {\varphi }_s$ modulation data from SIDIS along with its contribution to the single transverse-spin asymmetry in pion production from proton-proton collisions. We also explore the impact of lattice QCD tensor charge calculations and the Soffer bound on our global analysis. We find that both constraints can be accommodated within our results, with $\tilde{H}$ playing a key role in maintaining agreement with the data from proton-proton collisions.

    hep-phhep-exnucl-exnucl-thPRD(2022)·81 citations
25. 25*

    A split seesaw model with hidden neutrinoless double beta decay but successful leptogenesis

    Zhen-hua Zhao🇨🇳

    In a paper by Asaka, Ishida and Tanaka \cite{hiding}, they proposed a novel possibility (which will be referred to as the AIT ansatz) that, in spite of the Majorana nature of neutrinos, the neutrinoless double beta ($0\nu \beta \beta$) decay can be hidden. In the original AIT model, the AIT ansatz is realized in the minimal seesaw model with two right-handed neutrinos which have a hierarchical mass structure: the lighter and heavier right-handed neutrinos are respectively much lighter and heavier than the typical Fermi-momentum scale of nuclei. However, the original AIT model does not accommodate a successful leptogenesis. For this problem, in this paper we study a split seesaw model with one lighter right-handed neutrino but two heavier right-handed neutrinos which can realize the AIT ansatz and accommodate a successful leptogenesis simultaneously. We first give the condition on the neutrino Yukawa couplings for realizing the AIT ansatz, discuss its realization by employing an Abelian flavor symmetry, and study its implications for the mixing of the lighter right-handed neutrino with three left-handed neutrinos. We then successively study the implications for leptogenesis of the interesting scenarios where $M_{\mathrm{D}}^{}$ is a triangular matrix (which has maximally-restricted texture zeros, in line with the simplicity principle) or respects the $\mu$-$\tau$ reflection symmetry (which is well motivated by the experimental results), on top of the AIT ansatz.

    hep-phEPJC(2022)·5 citations
26. 26*

    Anisotropic cosmic optical background bound for decaying dark matter in light of the LORRI anomaly

    Kazunori Nakayama🇯🇵 · Wen Yin🇯🇵

    Recently anomalous flux in the cosmic optical background (COB) has been reported by the New Horizon observations. The COB flux is $16.37\pm 1.47\mathrm{nW}{\mathrm{m}}^{-2}\mathrm{s}{\mathrm{r}}^{-1}$, at the LORRI pivot wavelength of $0.608\mu \mathrm{m}$, which is $\sim 4\sigma$ level above the expected flux from the Hubble Space Telescope (HST) galaxy count. It would be great if this were a hint for the eV scale dark matter decaying into photons. In this paper, we point out that such a decaying dark matter model predicts a substantial amount of anisotropy in the COB flux, which is accurately measured by the HST. The data of the HST excludes the decay rate of the dominant cold dark matter larger than $10^{-24}$-$10^{-23}{\mathrm{s}}^{-1}$ in the mass range of $5$-$20$eV. As a result, the decaying cold dark matter explaining the COB excess is strongly disfavored by the anisotropy bound. We discuss some loopholes: e.g. warm/hot dark matter or two-step decay of the dark matter, to explain the COB excess.

    hep-phastro-ph.COhep-exPRD(2022)·56 citations
27. 27*

    The diffuse supernova neutrino background as a probe of late-time neutrino mass generation

    André de Gouvêa🇺🇸 · Ivan Martinez-Soler🇺🇸 · Yuber F. Perez-Gonzalez🇬🇧 · Manibrata Sen🇩🇪

    The relic neutrinos from old supernova explosions are among the most ancient neutrino fluxes within experimental reach. Thus, the diffuse supernova neutrino background (DSNB) could teach us if neutrino masses were different in the past (redshifts $z\lesssim 5$). Oscillations inside the supernova depend strongly on the neutrino mass-squared differences and the values of the mixing angles, rendering the DSNB energy spectrum sensitive to variations of these parameters. Considering a purely phenomenological parameterization of the neutrino masses as a function of redshift, we compute the expected local DSNB spectrum here on Earth. Given the current knowledge of neutrino oscillation parameters, specially the fact that $|U_{e3}{|}^2$ is small, we find that the ${\nu }_e$ spectrum could be significantly different from standard expectations if neutrinos were effectively massless at $z\gtrsim 1$ as long as the neutrino mass ordering is normal. On the other hand, the ${\overline{\nu }}_e$ flux is not expected to be significantly impacted. Hence, a measurement of both the neutrino and antineutrino components of the DSNB should allow one to test the possibility of recent neutrino mass generation.

    hep-phastro-ph.COPRD(2022)·23 citations
28. 28*

    Classical Cosmological Collider Physics and Primordial Features

    Xingang Chen🇺🇸 · Reza Ebadi🇺🇸 · Soubhik Kumar🇺🇸

    Features in the inflationary landscape can inject extra energies to inflation models and produce on-shell particles with masses much larger than the Hubble scale of inflation. This possibility extends the energy reach of the program of cosmological collider physics, in which signals associated with these particles are generically Boltzmann-suppressed. We study the mechanisms of this classical cosmological collider in two categories of primordial features. In the first category, the primordial feature is classical oscillation, which includes the case of coherent oscillation of a massive field and the case of oscillatory features in the inflationary potential. The second category includes any sharp feature in the inflation model. All these classical features can excite unsuppressed quantum modes of other heavy fields which leave observational signatures in primordial non-Gaussianities, including the information about the particle spectra of these heavy degrees of freedom.

    hep-phastro-ph.COgr-qchep-thJCAP(2022)·66 citations
29. 29*

    Brief history of the pion-nucleon sigma term

    J. M. Alarcón🇪🇸

    The pion-nucleon sigma term is a quantity involved in many important aspects of particle and nuclear physics. In this review I show its origin and how it is connected to important questions as the origin of mass of the ordinary matter, studies of dark matter detection and nucleosynthesis. I mention the most common methods used to obtain the sigma term, and comment on the extracted values. As it is shown, the accepted value of the sigma term has been moving from relatively low ($\sim 40$ MeV) to larger ones ($\sim 60$ MeV) until today, where this controversy still persist.

    hep-phhep-latnucl-thEur.Phys.J.ST(2021)·26 citations
30. 30*

    Practical Jet Flavour Through NNLO

    Simone Caletti🇮🇹 · Andrew J. Larkoski🇺🇸 · Simone Marzani🇮🇹 · Daniel Reichelt🇬🇧

    An infrared and collinear (IRC) safe definition of the partonic flavour of a jet is vital for precision predictions of quantum chromodynamics at colliders. Jet flavour definitions have been presented in the literature, but they are typically defined through modification of the jet algorithm to be sensitive to partonic flavour at every stage of the clustering. While this does ensure that the sum of flavours in a jet is IRC safe, a flavour-sensitive clustering procedure is difficult to apply to realistic data. We introduce a distinct and novel approach to jet flavour that can be applied to any collection of partons defined by any algorithm. Our definition of jet flavour is the sum of flavours of all partons that remain after Soft Drop grooming, reclustered with the Jade algorithm. We prove that this prescription is IRC safe through next-to-next-to-leading order (NNLO), and so can interface with the most precise fixed-order calculations for jets available at present. We validate the IRC safety of this definition with numeric fixed-order codes and further show that jet flavour with Soft Drop reclustered with a generalised kT algorithm fails to be IRC safe at NNLO.

    hep-phEPJC(2022)·65 citations
31. 31*

    Muon and electron $g-2$ anomalies in a flavor conserving 2HDM with an oblique view on the CDF $M_W$ value

    Francisco J. Botella🇪🇸 · Fernando Cornet-Gomez🇪🇸 · Carlos Miró🇪🇸 · Miguel Nebot🇪🇸

    We consider a type I or type X two Higgs doublets model with a modified lepton sector. The generalized lepton sector is also flavor conserving but with the new Yukawa couplings completely decoupled from lepton mass proportionality. The model is one loop stable under renormalization group evolution and it allows to reproduce the $g-2$ muon anomaly together with the different scenarios one can consider for the electron $g-2$ anomaly, related to the Cesium and/or to the Rubidium recoil measurements of the fine structure constant. Thorough parameter space analyses are performed to constrain all the model parameters in the different scenarios, either including or not including the recent CDF measurement of the W boson mass. For light new scalars with masses in the $0.2$-$1.0$ TeV range, the muon anomaly receives dominant one loop contributions; it is for heavy new scalars with masses above $1.2$ TeV that two loop Barr-Zee diagrams are needed. The electron $g-2$ anomaly, if any, must always be obtained with the two loop contributions. The final allowed regions are quite sensitive to the assumptions about perturbativity of Yukawa couplings, which influence unexpected observables like the allowed scalar mass ranges. On that respect, intermediate scalar masses, highly constrained by direct LHC searches, are allowed provided that the new lepton Yukawa couplings are fully scrutinized, including values up to 250 GeV. In the framework of a complete model, fully numerically analysed, we show the implications of the recent $M_W$ measurement.

    hep-phhep-exEPJC(2022)·51 citations
32. 32*

    A Fragmentation Approach to Jet Flavor

    Simone Caletti🇮🇹 · Andrew J. Larkoski🇺🇸 · Simone Marzani🇮🇹 · Daniel Reichelt🇬🇧

    An intuitive definition of the partonic flavor of a jet in quantum chromodynamics is often only well-defined in the deep ultraviolet, where the strong force becomes a free theory and a jet consists of a single parton. However, measurements are performed in the infrared, where a jet consists of numerous particles and requires an algorithmic procedure to define their phase space boundaries. To connect these two regimes, we introduce a novel and simple partonic jet flavor definition in the infrared. We define the jet flavor to be the net flavor of the partons that lie exactly along the direction of the Winner-Take-All recombination scheme axis of the jet, which is safe to all orders under emissions of soft particles, but is not collinear safe. Collinear divergences can be absorbed into a perturbative fragmentation function that describes the evolution of the jet flavor from the ultraviolet to the infrared. The evolution equations are linear and a small modification to traditional DGLAP and we solve them to leading-logarithmic accuracy. The evolution equations exhibit fixed points in the deep infrared, we demonstrate quantitative agreement with parton shower simulations, and we present various infrared and collinear safe observables that are sensitive to this flavor definition.

    hep-phJHEP(2022)·46 citations
33. 33*

    On the Standard Model Predictions for Rare K and B Decay Branching Ratios: 2022

    Andrzej J. Buras🇩🇪

    In this decade one expects a very significant progress in measuring the branching ratios for several rare $K$ and $B$ decays, in particular for the decays $K^{+}\to {\pi }^{+}\nu \bar{\nu }$, $K_L\to {\pi }^0\nu \bar{\nu }$, $B_s\to {\mu }^{+}{\mu }^{+}$ and $B_d\to {\mu }^{+}{\mu }^{+}$. On the theory side a very significant progress on calculating these branching ratios has been achieved in the last thirty years culminating recently in rather precise SM predictions for them. It is then unfortunate that some papers still cite the results for $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ and $K_L\to {\pi }^0\nu \bar{\nu }$ presented by us in 2015. They are clearly out of date. Similar comments apply to predictions for $B_{s,d}\to {\mu }^{+}{\mu }^{-}$. In this note I want to stress again that, in view of the tensions between various determinations of $V_{cb}$ in tree-level decays, presently, the only trustable SM predictions for the branching ratios in question can be obtained by eliminating their dependence on the CKM parameters with the help of $|{\epsilon }_K|$, $\Delta M_s$, $\Delta M_d$ and $S_{\psi K_S}$, evaluated in the SM. In this context I am astonished by statements made by some computer code practitioners that setting in this strategy these four $\Delta F=2$ observables to their experimental values is an assumption. The goal of this strategy is not to make an overall SM fit but to predict the SM branching ratios. In the SM there are no new physics (NP) contributions to $\Delta F=2$ transitions and no assumption on the absence of NP is needed. Moreover, presently NP is not required to describe simultaneously the very precise data on $|{\epsilon }_K|$, $\Delta M_s$, $\Delta M_d$ and $S_{\psi K_S}$. This strategy for obtaining true SM predictions for rare decay branching ratios is moreover not polluted by hadronic uncertainies and observed anomalies in semi-leptonic decays used often in global analyses as stressed recently in (arxiv: 2209.03968).

    hep-phhep-exhep-lat8 citations
34. 34*

    Viable quark-lepton Yukawa ratios and nucleon decay predictions in $SU(5)$ GUTs with type-II seesaw

    Stefan Antusch🇨🇭 · Kevin Hinze🇨🇭 · Shaikh Saad🇨🇭

    We investigate the viability of predictive schemes for quark-lepton Yukawa ratios and nucleon decay in non-supersymmetric SU(5) Grand Unified Theories (GUTs) where neutrino masses are generated by a type II seesaw mechanism. The scalar sector of the considered scenario contains 5-, 24- and 45-dimensional representations plus a 15-dimensional representation for realising the type II seesaw. Predictions for the ratios of the quark and lepton Yukawa couplings emerge when the relevant entries of the Yukawa matrices are generated from single joint GUT operators (i.e. under the condition of "single operator dominance"). Focusing on the 2nd and 3rd family and hierarchical Yukawa matrices, we show that only two sets of predictions, $\frac{y_{\tau }}{y_b}=\frac{3}{2}$, $\frac{y_{\mu }}{y_s}=\frac{9}{2}$ and $\frac{y_{\tau }}{y_b}=2$, $\frac{y_{\mu }}{y_s}=6$ are viable. To further investigate both options, we extend the minimal scenarios to two "toy models", including the 1st family of charged fermions, and calculate the models' predictions, e.g. for the nucleon decay rates and for the masses of the light relics that are potentially within reach of colliders.

    hep-phNPB(2023)·20 citations
35. 35*

    Summary of the parallel session HR3

    Shokoufe Faraji🇩🇪

    This is the summary of the parallel session entitled "Time and Philosophy in Physics", chaired by Shokoufe Faraji at the sixteenth Marcel Grossmann Meeting. This parallel session aimed to discuss open issues related to Time and fundamental laws from different perspectives in a complementary point of view.

    hep-phgr-qcphysics.hist-phThe Sixteenth Marcel Grossmann Meeting, p…·0 citations
36. 36*

    Perturbative approaches in relativistic kinetic theory and the emergence of first-order hydrodynamics

    Gabriel S. Rocha🇧🇷 · Gabriel S. Denicol🇧🇷 · Jorge Noronha🇺🇸

    Hydrodynamics can be formulated in terms of a perturbative series in derivatives of the temperature, chemical potential, and flow velocity around an equilibrium state. Different formulations for this series have been proposed over the years, which consequently led to the development of various hydrodynamic theories. In this work, we discuss the relativistic generalizations of the perturbative expansions put forward by Chapman and Enskog, and Hilbert, using general matching conditions in kinetic theory. This allows us to describe, in a comprehensive way, how different out-of-equilibrium definitions for the hydrodynamic fields affect the development of the hydrodynamic perturbative series. We provide a perturbative method for systematically deriving the hydrodynamic formulation recently proposed by Bemfica, Disconzi, Noronha, and Kovtun (BDNK) from relativistic kinetic theory. The various transport coefficients that appear in BDNK (at first-order) are explicitly computed using a new formulation of the relaxation time approximation for the Boltzmann equation. Assuming Bjorken flow, we also determine the hydrodynamic attractors of BDNK theory and compare the overall hydrodynamic evolution obtained using this formulation with that generated by the Israel-Stewart equations of motion and also kinetic theory.

    ↳ nucl-thhep-phhep-thPRD(2022)·46 citations
37. 37*

    Implications of the isobar run results for chiral magnetic effect in heavy ion collisions

    Dmitri E. Kharzeev🇺🇸 · Jinfeng Liao🇺🇸 · Shuzhe Shi🇺🇸

    Chiral magnetic effect (CME) is a macroscopic transport phenomenon induced by quantum anomaly in the presence of chiral imbalance and an external magnetic field. Relativistic heavy ion collisions provide the unique opportunity to look for CME in a non-Abelian plasma, where the chiral imbalance is created by topological transitions similar to those occurring in the Early Universe. The isobar run at Relativistic Heavy Ion Collider was proposed as a way to separate the possible CME signal driven by magnetic field from the background. The first blind analysis results from this important experiment have been recently released by the STAR Collaboration. Under the pre-defined assumption of identical background in RuRu and ZrZr, the results are inconsistent with the presence of CME, as well as with all existing theoretical models (whether including CME or not). However the observed difference of backgrounds must be taken into account before any physical conclusion is drawn. In this paper, we show that once the observed difference in hadron multiplicity and collective flow are quantitatively taken into account, the STAR results could be consistent with a finite CME signal contribution of about $(6.8\pm 2.6)\%$.

    ↳ nucl-thhep-phnucl-exPRC(2022)·46 citations
38. 38*

    Universality in Anomaly Flow

    Yutaka Hosotani🇯🇵

    Universality in anomaly flow by an Aharonov-Bohm (AB) phase ${\theta }_H$ is shown in the flat $M^4\times (S^1/Z_2)$ spacetime and in the Randall-Sundrum (RS) warped space. We analyze $SU(2)$ gauge theory with doublet fermions. With orbifold boundary conditions the $U(1)$ part of gauge symmetry remains unbroken at ${\theta }_H=0$ and $\pi$. Chiral anomalies smoothly vary with ${\theta }_H$ in the RS space. It is shown that anomaly coefficients associated with this anomaly flow are expressed in terms of the values of the wave functions of gauge fields at the UV and IR branes in the RS space. The anomaly coefficients depend on ${\theta }_H$, the warp factor of the RS space, and the orbifold boundary conditions for fermions, but not on the bulk mass parameters of fermions.

    ↳ hep-thhep-phPTEP(2022)·5 citations
39. 39*

    On the vacuum structure of gauge-Higgs unification models

    Yuki Adachi🇯🇵 · C.S. Lim🇯🇵 · Nobuhito Maru🇯🇵

    In this paper, we discuss the vacuum structure of the gauge-Higgs unification theory, which is one of the attractive candidates of physics beyond the standard model. This scenario has a remarkable feature, namely it has infinitely degenerate vacua due to the characteristic periodic potential of the Higgs filed, to be identified with the extra space component of the higher dimensional gauge field. We address a question, whether to form the superposition of such degenerate vacua, like the $\theta$-vacuum in QCD, is necessary or not, in order to realize the true vacuum state of the theory. We derive gauge field configuration which describes the transition between neighboring vacua, like the instanton (or anti-instanton) solution in QCD, and the corresponding Euclidean action in two models. In a simplified 2-dimensional U(1) model, the derived configuration to describe the transition is shown to have finite Euclidean action, and accordingly the "$\theta$-vacuum" and the resultant "$\theta$-term" are formulated. In a realistic 5D U(1) model, however, the gauge field configuration to describe the transition is shown to have infinite Euclidean action and therefore the tunneling probability between the degenerate vacua vanishes. Thus the superposition of the degenerate vacua is not necessary.

    ↳ hep-thhep-phPTEP(2022)·4 citations
40. 40*

    Spacetime evolution during moduli stabilization in radiation dominated era beyond 4D effective theory

    Hajime Otsuka🇯🇵 · Yutaka Sakamura🇯🇵

    We investigate the time evolution of the background spacetime during the moduli stabilization process, which is assumed to occur in the radiation dominated era. The setup is basically the Salam-Sezgin model, but we add a potential term for the dilaton in order to stabilize the moduli completely. We numerically solve the higher-dimensional background field equations, including a case that the stabilization process cannot be described within the 4D effective theory. In contrast to the conventional 4D effective theory analysis, we find that when the mass scale of the stabilization is larger than the compactification scale, the radiation contribution to the total energy density remains to be non-negligible for a much longer time than the stabilization time scale. As a result, the non-compact 3D space expands slower than the matter dominated universe. We also find the equation of state for the radiation $w_{\mathrm{rad}}$ remains to be smaller than 1/3 for a long time, which indicates that the radiation still feels the extra dimensions for a while even after the moduli are stabilized.

    ↳ hep-thhep-phJHEP(2022)·3 citations
41. 41*

    Holographic Schwinger-Keldysh field theory of SU(2) diffusion

    Yanyan Bu🇨🇳 · Xiyang Sun🇨🇳 · Biye Zhang🇨🇳

    We construct effective field theory for SU(2) isospin charge diffusion, based on holographic Schwinger-Keldysh contour arXiv:2008.01269. The holographic model consists of a probe SU(2) gauge field in a doubled Schwarzschild-AdS${}_5$ geometry. Accurate to first order in derivative expansion, we analytically compute the effective action up to quartic order in hydrodynamical fields. The effective theory contains both non-Gaussianity for noises and nonlinear interactions between noises and dynamical variables. Moreover, the effective theory captures both thermal and quantum fluctuations, which perfectly satisfy dynamical Kubo-Martin-Schwinger (KMS) symmetry at quantum level. Interestingly, the dynamical KMS symmetry, which is crucial in formulating non-equilibrium effective field theory for a quantum many-body system, is found to have a nice holographic interpretation.

    ↳ hep-thhep-phnucl-thJHEP(2022)·14 citations
42. 42*

    Rate and ellipticity of dilepton production in a magnetized quark-gluon plasma

    Xinyang Wang🇨🇳 · Igor A. Shovkovy🇺🇸

    Using the Landau-level representation for the imaginary part of the photon polarization tensor, we derive an explicit expression for the dilepton production rate from a hot quark-gluon plasma in a quantizing background magnetic field. We study in detail the dependence of the production rate on the dilepton invariant mass and the transverse momentum at mid-rapidity. We also investigate the angular dependence and ellipticity of dilepton emission. By comparing the result with the zero-field Born approximation, we find that the magnetic field leads to a strong enhancement of the dilepton rate at small values of the invariant mass ($M\lesssim \sqrt{|eB|}$). In the same kinematic region, the dilepton production is characterized by a sizable ellipticity. At large values of the dilepton invariant mass ($M\gtrsim \sqrt{|eB|}$), the role of the magnetic field decreases and the result approaches the isotropic zero-field Born rate. By investigating the dependence of ellipticity on the transverse momentum, we argue that the future measurements of dilepton rate in the region of small invariant masses can constrain the magnetic field produced in heavy-ion collisions.

    ↳ nucl-thhep-phPRD(2022)·34 citations
43. 43*

    On possible composite structure of scalar fields in expanding universe

    A.A. Zheltukhin🇺🇦

    Scalar fields in curved backgrounds are assumed to be composite objects. As an example realizing such a possibility we consider a model of the massless tensor field $l_{\mu \nu }(x)$ in a 4-dim. background $g_{\mu \nu }(x)$ with spontaneously broken Weyl and scale symmetries. It is shown that the potential of $l_{\mu \nu }$, represented by a scalar quartic polynomial, has the degenerate extremal described by the composite Nambu-Goldstone scalar boson $\varphi (x):=g^{\mu \nu }{l}_{\mu \nu }$. Removal of the degeneracy shows that $\varphi$ acquires a non-zero vev $⟨\varphi {⟩}_0=\mu$ which, together with the free parameters of the potential, defines the cosmological constant. The latter is zero for a certain choice of the parameters.

    ↳ hep-thgr-qchep-phEPJC(2023)·3 citations
44. 44*

    Fisher matrix for the one-loop galaxy power spectrum: measuring expansion and growth rates without assuming a cosmological model

    Luca Amendola (Heidelberg University, Germany)🇩🇪 · Massimo Pietroni (University of Parma and INFN, Italy)🇮🇹 · Miguel Quartin (Universidade Federal do Rio de Janeiro, Brazil and Heidelberg University, Germany)🇩🇪

    We introduce a methodology to extend the Fisher matrix forecasts to mildly non-linear scales without the need of selecting a cosmological model. We make use of standard non-linear perturbation theory for biased tracers complemented by counterterms, and assume that the cosmological distances can be measured accurately with standard candles. Instead of choosing a specific model, we parametrize the linear power spectrum and the growth rate in several $k$ and $z$ bins. We show that one can then obtain model-independent constraints of the expansion rate $E(z)=H(z)/H_0$ and the growth rate $f(k,z)$, besides the bias functions. We apply the technique to both Euclid and DESI public specifications in the range $0.6\le z\le 1.8$ and show that the gain in precision when going from $k_{\max }=0.1$ to $0.2h$/Mpc is around two- to threefold, while it reaches four- to ninefold when extending to $k_{\max }=0.3h$/Mpc. In absolute terms, with $k_{\max }=0.2h/$Mpc, one can reach high precision on $E(z)$ at each $z$-shell: 8-10% for DESI with $\Delta z=0.1$, 5-6% for Euclid with $\Delta z=0.2-0.3$. This improves to 1-2% if the growth rate $f$ is taken to be $k$-independent. The growth rate itself has in general much weaker constraints, unless assumed to be $k$-independent, in which case the gain is similar to the one for $E(z)$ and uncertainties around 5-15% can be reached at each $z$-bin. We also discuss how neglecting the non-linear corrections can have a large effect on the constraints even for $k_{\max }=0.1h/$Mpc, unless one has independent strong prior information on the non-linear parameters.

    ↳ astro-ph.COhep-phJCAP(2022)·20 citations
45. 45*

    Studies of the X(3872) at Belle II

    Elisabetta Prencipe (on behalf of the Belle II collaboration)🇩🇪

    The X(3872) is one of the most puzzling resonances ever observed. First seen by the Belle Collaboration in 2003, it solicited the effort of a hundred of experimental physicists and dozens of theorists, who nowadays are trying yet to shed light on the nature of this peculiar resonant state. It was seen in several decay modes and different production mechanisms, and confirmed by several experiments, so it is well established, and recently is addressed as the ${\chi }_{c1}(3872)$. Here we report about a re-discovery of the X(3872) with early Belle II data, and discuss plans for future measurements once the full integrated planned luminosity will be achieved by Belle II.

    ↳ hep-exhep-phRev.Mex.Fis.Suppl.(2022)·1 citation
46. 46*

    Higgs inflation and scalar weak gravity conjecture

    Yang Liu🇬🇧

    In this article, we intend to find a specific model which can satisfy the further refining dS swampland conjecture and scalar weak gravity conjecture (SWGC) simultaneously, in particular, Higgs inflation model and its two extensions: Higgs-Dilaton model and Palatini Higgs inflation. We find that although Higgs inflation model and Higgs-Dilaton model could satisfy the further refining dS swampland conjecture, the two models cannot satisfy SWGC and its strong version. While Palatini Higgs inflation could satisfy these conjectures simultaneously. Therefore Palatini Higgs inflation could be a "real" inflation model of the universe.

    ↳ gr-qchep-phEPJC(2022)·15 citations
47. 47*

    Symmetry restoration, Tunnelling and the Null Energy Condition

    Jean Alexandre🇬🇧 · Janos Polonyi🇫🇷

    A finite volume allows tunnelling between degenerate vacua in Quantum Field Theory, and leads to remarkable energetic features, arising from the competition of different saddle points in the partition function. We describe this competition for finite temperature at equilibrium, taking into account both static and (Euclidean) time-dependent saddle points. The effective theory for the homogeneous order parameter yields a non-extensive vacuum energy at low temperatures, implying a dynamical violation of the Null Energy Condition.

    ↳ hep-thhep-phPRD(2022)·11 citations
48. 48*

    Theoretical study of the $\gamma d\to {\pi }^0\eta d$ reaction

    A. Martinez Torres🇧🇷 · K. P. Khemchandani🇧🇷 · E. Oset🇪🇸

    We have done a theoretical study of the $\gamma d\to {\pi }^0\eta d$ reaction starting with a realistic model for the $\gamma N\to {\pi }^0\eta N$ reaction that reproduces cross sections and polarization observables at low energies and involves the $\gamma N\to \Delta (1700)\to \eta \Delta (1232)\to \eta {\pi }^{0}N$ process. For the coherent reaction in the deuteron we considered the impulse approximation together with the rescattering of the pions and the $\eta$ on a different nucleon than the one where they are produced. We found this second mechanism very important since it helps share between two nucleons the otherwise large momentum transfer of the reaction. Other contributions to the $\gamma d\to {\pi }^0\eta d$ reaction, involving the $\gamma N\to {\pi }^{\pm }{\pi }^0{N}^{\prime }$ process, followed by the rescattering of the ${\pi }^{\pm }$ with another nucleon to give $\eta$ and a nucleon, have also been included. We find a natural explanation, tied to the dynamics of our model, for the shift of the $\eta -d$ mass distribution to lower invariant masses, and of the ${\pi }^0-d$ mass distribution to larger invariant masses, compared to a phase space calculation. We also study theoretical uncertainties related to the large momenta of the deuteron wave function involved in the process as well as to the couplings present in the model. Striking differences are found with the experimental angular distribution and further theoretical investigations might be necessary.

    ↳ nucl-thhep-phnucl-exPRC(2023)·10 citations
49. 49*

    Measuring Galactic Dark Matter through Unsupervised Machine Learning

    Matthew R Buckley🇺🇸 · Sung Hak Lim🇺🇸 · Eric Putney🇺🇸 · David Shih🇺🇸

    Measuring the density profile of dark matter in the Solar neighborhood has important implications for both dark matter theory and experiment. In this work, we apply autoregressive flows to stars from a realistic simulation of a Milky Way-type galaxy to learn -- in an unsupervised way -- the stellar phase space density and its derivatives. With these as inputs, and under the assumption of dynamic equilibrium, the gravitational acceleration field and mass density can be calculated directly from the Boltzmann Equation without the need to assume either cylindrical symmetry or specific functional forms for the galaxy's mass density. We demonstrate our approach can accurately reconstruct the mass density and acceleration profiles of the simulated galaxy, even in the presence of Gaia-like errors in the kinematic measurements.

    ↳ astro-ph.GAhep-phMNRAS(2023)·26 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.