Tue·Sep 14, 2021Tuesday·September 14, 2021

1. 01*

   On a novel evalutation of the hadronic contribution to the muon's $g-2$ from QCD

   Marco Frasca🇮🇹 · Anish Ghoshal🇵🇱 · Stefan Groote🇪🇪

   We evaluate the hadronic contribution to the $g-2$ of the muon by deriving the low-energy limit of quantum chromodynamics (QCD) and computing in this way the hadronic vacuum polarization. The low-energy limit is a non-local Nambu--Jona-Lasinio (NJL) model that has all the parameters fixed from QCD, and the only experimental input used is the confinement scale that is known from measurements of hadronic physics. Our estimations provide a novel analytical alternative to the current lattice computations and we find that our result is close to the similar computation performed from experimental data. We also comment on how this analytical approach technique, in general, may provide prospective estimates for hadronic computations from dark sectors and its implication in BSM model-building in future.

   hep-phhep-exPRD(2021)·16 citations
2. 02*

   Apparent strangeness enhancement from multiplicity selection in high energy proton-proton collisions

   Constantin Loizides (ORNL)🇺🇸 · Andreas Morsch (CERN)🇨🇭

   The increase of strange-particle yields relative to pions versus charged-particle multiplicity in proton-proton (pp) collisions at the LHC is usually described by microscopic or hydrodynamical models as a result of the increasing density of produced partons or strings and their interactions. Instead, we consider the multiple partonic interaction (MPI) picture originally developed in the context of the PYTHIA event generator. We find that strangeness enhancement in PYTHIA is hidden by a large excess of low-$p_{\mathrm{T}}$ multi-strange baryons, which mainly results from the hadronization of $u$-quark, $d$-quark and gluon ($udg$) strings. Strange baryons produced in strings formed from parton showers initiated by strange quarks ($s$-fragmentation), however, describe well the spectral shapes of $\Xi$ and $\Omega$ baryons and their multiplicity dependence. Since the total particle yield contains contributions from soft and hard particle production, which cannot be experimentally separated, we argue that the correct description of the $p_{\mathrm{T}}$-spectra is a minimum requirement for meaningful comparisons of multiplicity dependent yield measurements to MPI based calculations. We demonstrate that the $s$-fragmentation component describes the increase of average $p_{\mathrm{T}}$ and yields with multiplicity seen in the data, including the approximate multiplicity scaling for different collision energies. When restricted to processes that reproduce the measured $p_{\mathrm{T}}$-spectra, the MPI framework exhibits a smooth evolution from strictly proportional multiplicity scaling ($K_{\mathrm{S}}^0$, $\Lambda$, where the $udg$-hadronization component dominates) to linearity ($s$-fragmentation) and on to increasingly non-linear behavior ($c$-, $b$-quark and high-$p_{\mathrm{T}}$ jet fragmentation), hence providing a unified approach for particle production in pp collisions.

   hep-phhep-exnucl-ex9 citations
3. 03*

   Charged particle to photon ratio in heavy-ion collisions at RHIC: a different point of view

   Mohammad Asif Bhat🇮🇳 · Supriya Das🇮🇳

   We report an alternative explanation of the variation of charged particle to photon ratio in Cu+Cu collisions and Au+Au collisions from 1.4 $\pm$ 0.1 to 1.2 $\pm$ 0.1 at $\sqrt{s_{\mathrm{NN}}}$ = 62.4 GeV and 200 GeV respectively in STAR experiment at RHIC. Based on the theoretical predictions and experimental results we argue that the additional contribution of direct photons at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV in both Cu+Cu and Au+Au collisions are improving the ratio $\frac{N_{ch}}{N_{\gamma }}$ to 1.2 $\pm$ 0.1 from 1.4 $\pm$ 0.1.

   hep-phnucl-th0 citations
4. 04*

   Triply heavy tetraquark states

   Xin-Zhen Weng🇨🇳 · Wei-Zhen Deng🇨🇳 · Shi-Lin Zhu🇨🇳

   In the framework of an extended chromomagnetic model, we systematically study the mass spectrum of the $S$-wave $qQ\bar{Q}\bar{Q}$ tetraquarks. Their mass spectra are mainly determined by the color interaction. For the $qc\bar{c}\bar{c}$, $qb\bar{c}\bar{c}$ and $qb\bar{b}\bar{b}$ tetraquarks, the color interaction favors the color-sextet $|(qQ{)}^{6_c}(\bar{Q}\bar{Q}{)}^{{\bar{6}}_c}⟩$ configuration over the color-triplet $|(qQ{)}^{{\bar{3}}_c}(\bar{Q}\bar{Q}{)}^{3_c}⟩$ one. But for the $qc\bar{b}\bar{b}$ tetraquarks, the color-triplet configuration is favored. We find no stable states which lie below the thresholds of two pseudoscalar mesons. The lowest axial-vector states with the $qQ\bar{b}\bar{b}$ flavor configuration may be narrow. They lie just above the thresholds of two pseudoscalar mesons, but cannot decay into these channels because of the conservation of the angular momentum and parity.

   hep-phPRD(2022)·29 citations
5. 05*

   Thermal Perturbations from Cosmological Constant Relaxation

   Lingyuan Ji🇺🇸 · David E. Kaplan🇺🇸 · Surjeet Rajendran🇺🇸 · Erwin H. Tanin🇺🇸

   We probe the cosmological consequences of a recently proposed class of solutions to the cosmological constant problem. In these models, the universe undergoes a long period of inflation followed by a contraction and a bounce that sets the stage for the hot big bang era. A requirement of any successful early universe model is that it must reproduce the observed scale-invariant density perturbations at CMB scales. While these class of models involve a long period of inflation, the inflationary Hubble scale during their observationally relevant stages is at or below the current Hubble scale, rendering the de Sitter fluctuations too weak to seed the CMB anisotropies. We show that sufficiently strong perturbations can still be sourced thermally if the relaxion field serving as the inflaton interacts with a thermal bath, which can be generated and maintained by the same interaction. We present a simple model where the relaxion field is derivatively (i.e. technically naturally) coupled to a non-abelian gauge sector, which gets excited tachyonically and subsequently thermalizes due to its nonlinear self-interactions. This model explains both the smallness of the cosmological constant and the amplitude of CMB anisotropies.

   hep-phastro-ph.COgr-qchep-thPRD(2022)·15 citations
6. 06*

   Anomalous Magnetic Moment and Higgs Coupling of the Muon in a Sequential U(1) Gauge Model with Dark Matter

   Rathin Adhikari🇮🇳 · Imtiyaz Ahmad Bhat🇮🇳 · Debasish Borah🇮🇳 · Ernest Ma🇺🇸 · Dibyendu Nanda🇮🇳

   We study an Abelian gauge extension of the standard model with fermion families having non-universal gauge charges. The gauge charges and scalar content are chosen in such an anomaly-free way that only the third generation fermions receive Dirac masses via renormalisable couplings with the Higgs boson. Incorporating additional vector like fermions and scalars with appropriate $U(1)$ charges can lead to radiative Dirac masses of first two generations with neutral fermions going in the loop being dark matter candidates. Focusing on radiative muon mass, we constrain the model from the requirement of satisfying muon mass, recently measured muon anomalous magnetic moment by the E989 experiment at Fermilab along with other experimental bounds including the large hadron collider (LHC) limits. The anomalous Higgs coupling to muon is constrained from the LHC measurements of Higgs to dimuon decay. The singlet fermion dark matter phenomenology is discussed showing the importance of both annihilation and coannihilation effects. Incorporating all bounds lead to a constrained parameter space which can be probed at different experiments.

   hep-phastro-ph.COhep-exPRD(2022)·5 citations
7. 07*

   The $g_T(x)$ contribution to single spin asymmetries in SIDIS

   Sanjin Benić🇭🇷 · Yoshitaka Hatta🇺🇸 · Abhiram Kaushik🇭🇷 · Hsiang-nan Li🇹🇼

   Motivated by a novel origin of transverse single spin asymmetry (SSA) in semi-inclusive Deep Inelastic Scattering (SIDIS) uncovered by some of us, we quantitatively investigate its impact on the theoretical understanding of the mechanism responsible for SSA. This new contribution from the quark-initiated channel first appears in two-loop perturbation theory and involves the $g_T(x)$ distribution. We point out another entirely analogous piece from the gluon-initiated channel proportional to the gluon helicity distribution $\Delta G(x)$. Both contributions are solely expressed in terms of twist-two polarized parton distribution functions and twist-two fragmentation functions in the Wandzura-Wilczek approximation, such that they can be unambiguously evaluated without introducing free parameters. We make predictions for measurements of the asymmetries $A_{UT}$ at the future Electron-Ion Collider (EIC), and find that $A_{UT}$ associated with the $\sin ({\varphi }_h-{\varphi }_S)$, $\sin {\varphi }_S$ and $\sin (2{\varphi }_h-{\varphi }_S)$ harmonics can reach up to 1-2\% even at the top EIC energy.

   hep-phhep-exPRD(2021)·14 citations
8. 08*

   Cosmological baryon/lepton asymmetry in terms of Kaluza-Klein extra dimensions

   Valery V. Nikulin🇷🇺 · Sergey G. Rubin🇷🇺

   In this article, we discuss the mechanism for generating the lepton/baryon number and its subsequent conservation based on extradimensional evolution. The internal angular momentum of extra space is related to the lepton/baryon charge. Extra space metric are assumed to be initially asymmetric. Symmetries appear during inflation due to an increase in entropy. Using the multidimensional field toy model, we show that internal angular momentum can accumulate in fermions, which could explain the lepton/baryon asymmetry of the Universe.

   hep-phgr-qchep-thInt.J.Mod.Phys.D(2021)·2 citations
9. 09*

   Laser-assisted charged Higgs pair production in Inert Higgs Doublet Model (IHDM)

   M. Ouali🇲🇦 · M. Ouhammou🇲🇦 · S. Taj🇲🇦 · R. Benbrik🇲🇦 · B. Manaut🇲🇦

   The production of a pair of charged Higgs bosons from $e^{+}{e}^{-}$ annihilation in the presence of a circularly polarized laser field is investigated in Inert Higgs doublet Model (IHDM) at $e^{+}{e}^{-}$ colliders. We have derived the analytical expression for the laser-assisted differential cross section by using the Dirac-Volkov formalism at leading order including the $Z$ and $\gamma$ diagrams. Since the laser-free cross section of this process depends, in the lowest order, only on the mass of the charged Higgs boson and the energy of the center of mass, we have analyzed the dependence of the total laser-assisted cross section on these parameters and also on the laser parameters such as the number of photons exchanged, the laser field intensity and its frequency. The results found indicate that the electromagnetic field decreases the order of magnitude of the total cross section as much as the laser field intensity increases or by decreasing its frequency. Moreover, it becomes high for low charged Higgs masses and low center of mass energies.

   hep-phPLB(2021)·19 citations
10. 10*

    Meson-Baryon Couplings Revisited

    N. F. Nasrallah🇱🇧

    The theoretical evaluation of the coupling constants gpiNN , gKNLambda and gKNSigma is undertaken using QCD sum rules. These quantities were previously calculated with exponential (Borel) kernels used to suppress the unknown contributions of the hadronic continua. This method however introduces arbitrariness and instability in the calculation. In order to avoid these I redo the calculation using polynomial kernels tailored to vanish at the baryonic resonance masses. The results are gpiNN = 12.5 +- 1.0, gKNSigma = 5.45 +- .4, gKNSigma= -(12.7 - 15.0) which are close to experiment and to the predictions of SU(3) and which , with the corresponding Goldberger-Treiman Discrepancy satisfy quite well the Dashen-Weinstein relation.

    hep-phnucl-th0 citations
11. 11*

    Quantum Entanglement and Axion Physics

    A. Nicolaidis🇬🇷

    The axion particle is the outcome of the proposed Peccei-Quinn mechanism for solving the strong CP problem. Axion is also a popular dark matter candidate. Thus there is an increased interest in establishing its existence. Axions couple to two photons and most experiments search for the transition of an axion into a photon, in the presence of a magnetic field. In our study we examine the coupling of the axion into a pair of entangled photons. The presence of a magnetic field changes the polarization correlations of the entagled photons, thus offering an unambiguous signature for axion existence

    hep-phMod.Phys.Lett.A(2022)·0 citations
12. 12*

    The $ggh$ variations

    Adam Martin🇺🇸 · Michael Trott🇩🇰

    We examine how sub-leading results in the operator and loop expansion for $\sigma (\mathcal{GG}\to h)$ in the Standard Model Effective Field Theory (SMEFT) inform theoretical error estimates when studying this production channel in global SMEFT studies. We also discuss the relationship between geometric SMEFT results and the $\kappa$ formalism.

    hep-phPRD(2022)·26 citations
13. 13*

    Impacts of EMC effects on the D meson modification factor in equilibrating QGP

    A. Mirjalili🇮🇷 · J. Sheibani🇮🇷 · K. Javidan🇮🇷 · R. Gharaei🇮🇷 · Shahin Atashbar Tehrani

    In this article we employ the nuclear EMC effect to extract the parton distribution functions (PDFs) inside the Lead (Pb) and Gold (Au) nuclei. Extracted PDFs are utilized to obtain the transverse momentum dependent (TMD) ones, using the computing codes like Pythia 8 or MCFM-10. Through this procedure TMDPDFs for charm and bottom quarks in Au at $\sqrt{s_{NN}}=200GeV$, Pb at $\sqrt{s_{NN}}=2.76TeV$ and $\sqrt{s_{NN}}=5.02TeV$ are calculated. To evaluate the validity of results and investigate the influence of nuclear EMC effect, the numerated TMDs are used as input to estimate heavy quark modification factor $R_{AA}$ at transverse plane $P_T$. This observable is calculated through numerical solution of the Fokker-Planck equation. For this purpose we need to extract the drag and diffusion coefficients, using the hard thermal loop correction. It is done in the frame work of the relativistic hydrodynamics up to the third order approximation of gradient expansion. The results are compared with same solutions when the input PFDs are considered inside the unbounded protons where the nuclear effect is not included. The comparison indicates a significant improvement of computed $R_{AA}$ with available experimental data when the EMC effect is considered.

    hep-phnucl-thEur.Phys.J.Plus(2022)·2 citations
14. 14*

    Purely leptonic decays of the ground charged vector mesons

    Yueling Yang🇨🇳 · Zhenglin Li🇨🇳 · Kang Li🇨🇳 · Jinshu Huang🇨🇳 · Junfeng Sun🇨🇳

    The study of the purely leptonic decays of the ground charged vector mesons is very interesting and significant in determining the CKM matrix elements, obtaining the decay constant of vector mesons, examining the lepton flavor universality, and searching for new physics beyond the standard model. These purely leptonic decays of the ground charged vector mesons are induced by the weak interactions within the standard model, and usually have very small branching ratios, $\mathcal{B}({\rho }^{-}\to {\ell }^{-}{\nu }_{\ell })$ $\sim$ $\mathcal{O}(10^{-13})$, $\mathcal{B}(K^{\ast -}\to {\ell }^{-}{\nu }_{\ell })$ $\sim$ $\mathcal{O}(10^{-13})$, $\mathcal{B}(D_d^{\ast -}\to {\ell }^{-}{\nu }_{\ell })$ $\sim$ $\mathcal{O}(10^{-10})$, $\mathcal{B}(B_u^{\ast -}\to {\ell }^{-}{\nu }_{\ell })$ $\sim$ $\mathcal{O}(10^{-10})$, $\mathcal{B}(D_s^{\ast -}\to {\ell }^{-}{\nu }_{\ell })$ $\sim$ $\mathcal{O}(10^{-6})$ and $\mathcal{B}(B_c^{\ast -}\to {\ell }^{-}{\nu }_{\ell })$ $\sim$ $\mathcal{O}(10^{-6})$. Inspired by the potential prospects of LHCb, Belle-II, STCF, CEPC and FCC-ee experiments, we discussed the probabilities of experimental investigation on these purely leptonic decays. It is found that the measurements of these decays might be possible and feasible with the improvement of data statistics, analytical technique, and measurement precision in the future. (1) With the hadron-hadron collisions, the purely leptonic decays of ${\rho }^{-}$, $K^{\ast -}$, $D_{d,s}^{\ast -}$ and $B_{u,c}^{\ast -}$ mesons might be accessible at LHC experiments. (2) With the $e^{+}{e}^{-}$ collisions, the purely leptonic decays of $D_{d,s}^{\ast -}$ and $B_{u,c}^{\ast -}$ mesons might be measurable with over $10^{12}$ $Z^0$ bosons available at CEPC and FCC-ee experiments. In addition, the $D_{d,s}^{\ast -}$ $\to$ ${\ell }^{-}{\nu }_{\ell }$ decays could also be studied at Belle-II and SCTF experiments.

    hep-phhep-exEPJC(2021)·16 citations
15. 15*

    Colour and baryon number fluctuation of preconfinement system in production process and T_cc structure

    Yi Jin🇨🇳 · Shi-Yuan Li🇨🇳 · Yan-Rui Liu🇨🇳 · Qin Qin🇨🇳 · Zong-Guo Si🇨🇳 · Fu-Sheng Yu🇨🇳

    We suggest to study the production mechanism and some details of the production properties to probe the structure of the DDpi resonance T_cc^+ recently observed by the LHCb Collaboration. If the resonance is produced as a four-quark state, one can find the corresponding finger prints via measurements on some production properties that are the same as those of Xi_cc. The reason is that a special colour connection on the interface between the perturbative and non perturbative QCD is required for these doubly-charm hadron production. On the other hand, if T_cc^+ is produced as a hadron molecule, the measurement on the momentum correlation of DD^* can be a smoking gun to make the judgement. The present data favour a compact four-quark state production via the cc diquark fragmentation.

    hep-phPRD(2021)·40 citations
16. 16*

    Same sign trilepton as signature of charged Higgs in two Higgs doublet model

    Tanmoy Mondal🇰🇷 · Prasenjit Sanyal🇰🇷

    We explored the prospect of looking for a fermiophobic charged Higgs ($\text{hpm}$) via the same sign trilepton signal at the LHC. A fermiophobic scenario appears in the type-I two Higgs doublet model where the coupling of the $\text{hpm}$ with the Standard Model fermions is inversely proportional to $\text{tb}$. Almost all the experimental searches rely on the fermionic production and decay of the charged Higgs. Consequently, the limit on $\text{hpm}$ for fermiophobic scenarios is non-existent unless $\text{tb}$ is small. We show that for a fermiophobic case, the electroweak production of $\text{hpm}$ is dominant for most of the parameter space. Subsequent bosonic decay of the charged and neutral Higgses give rise to the same sign trilepton signal. With a thorough phenomenological analysis, we demonstrate that the same sign trilepton signal can be an excellent complementary search to explore the high $\text{tb}$ regions.

    hep-phJHEP(2022)·18 citations
17. 17*

    Study of kinetic freeze-out parameters as function of rapidity in pp collisions at CERN SPS energies

    Muhammad Waqas🇨🇳 · H. M. Chen🇨🇳 · Guang Xiong Pen · Abd Al Karim Haj Ismail🇦🇪 · Muhammad Ajaz🇵🇰 · Zafar Wazir🇵🇰 · Ramoona Shehzadi🇵🇰 · Sabiha Jamal🇵🇰 · Atef AbdelKader🇦🇪

    We used the blast wave model with Boltzmann Gibbs statistics and analyzed the experimental data measured by NA61/SHINE Collaboration in inelastic (INEL) proton-proton collisions at different rapidity slices at different center-of-mass energies. The particles used in this study are pion, kaon, proton and anti-proton. We extracted kinetic freeze-out temperature, transverse flow velocity and kinetic freeze-out volume from the transverse momentum spectra of the particles. We observed that the kinetic freeze-out temperature is rapidity and energy dependent, while transverse flow velocity does not depend on them. Furthermore, we observed that the kinetic freeze-out volume is energy dependent but it remains constant with changing the rapidity. We also observed that all these three parameters are mass dependent. In addition, with the increase of mass, the kinetic freeze-out temperature increases, and the transverse flow velocity as well as kinetic freeze-out volume decreases.

    hep-phEntropy(2021)·18 citations
18. 18*

    Baryon decays $J/\psi \to B\bar{B}$ within the QCD factorisation framework

    Nikolay Kivel🇩🇪

    We investigate $J/\psi$ decays into octet baryon-antibaryons pairs. The decay amplitudes are computed within the collinear QCD factorisation framework. The subleading amplitude, which describes the decay of longitudinally polarised charmonium, is computed using twist-4 three-quark distribution amplitudes. The obtained results are used for a qualitative analysis of the experimental data. It is found that the polarisation parameter ${\alpha }_B$ can be described with an accuracy $10-30\%$, which may indicate that the pQCD contribution dominates this observable.

    hep-phEPJA(2022)·6 citations
19. 19*

    Dark Matter in Astrophysics/Cosmology

    Anne M. Green🇬🇧

    These lecture notes aim to provide an introduction to dark matter from the perspective of astrophysics/cosmology. We start with a rapid overview of cosmology, including the evolution of the Universe, its thermal history and structure formation. Then we look at the observational evidence for dark matter, from observations of galaxies, galaxy clusters, the anisotropies in the cosmic microwave background radiation and large scale structure. To detect dark matter we need to know how it's distributed, in particular in the Milky Way, so next we overview relevant results from numerical simulations and observations. Finally, we conclude by looking at what astrophysical and cosmological observations can tell us about the nature of dark matter, focusing on two particular cases: warm and self-interacting dark matter.

    hep-phastro-ph.COSciPost Phys.Lect.Notes(2022)·43 citations
20. 20*

    Higgs triplet extension of GRACE

    Yusaku Kouda🇯🇵 · Tadashi Kon🇯🇵 · Yoshimasa Kurihara🇯🇵 · Takahiro Ueda🇯🇵

    Much theoretical effort and automatization are required to confront new physics models with experimental data for many types of particle reactions at future colliders. In this context, we extend GRACE, an automatic calculation system for invariant amplitudes, to incorporate particles and interactions in the Georgi-Machacek model. With the extended GRACE system, we study fermiophobic Higgs boson production processes at $e^{+}{e}^{-}$ and $e^{-}{e}^{-}$ colliders in the model. The results show some advantages of $e^{-}{e}^{-}$ colliders over $e^{+}{e}^{-}$ colliders for new physics search and thus its complementary role.

    hep-phEPJC(2022)·0 citations
21. 21*

    Distinctive signals of boosted dark matter from its semi-annihilation

    Takashi Toma🇯🇵

    Dark matter can be boosted by various mechanisms, which may produce characteristic signals that are different from those of canonical dark matter. We show that the semi-annihilation $\chi \chi \to \bar{\chi }\nu$ produces signals that are distinctive from those of other semi-annihilation and standard dark matter annihilation processes. Because the boosted dark matter produced by the semi-annihilation process is regarded as a high-energy neutrino, the total flux of the dark matter and the accompanying neutrino produce double peaks in the energy close to the dark matter mass. We show that it will be possible to detect both of the particles produced at the Sun using future large volume neutrino detectors such as those of the Deep Underground Neutrino Experiment and Hyper-Kamiokande.

    hep-phastro-ph.HEhep-exPRD(2022)·23 citations
22. 22*

    System of evolution equations for quark and gluon jet quenching with broadening

    E. Blanco🇵🇱 · K. Kutak🇵🇱 · W. Placzek🇵🇱 · M. Rohrmoser🇵🇱 · K. Tywoniuk🇳🇴

    We propose a system of evolution equations that describe in-medium time-evolution of transverse-momentum-dependent quark and gluon fragmentation functions. Furthermore, we solve this system of equations using Monte Carlo methods. We then quantify the obtained solutions in terms of a few characteristic features, namely the average transverse momentum $⟨|k|⟩$ and energy contained in a cone, which allow us to see different behaviour of quark and gluon initiated final-state radiation. In particular, the later allows us to conclude that in the gluon-initiated processes there is less energy in a cone, so that the quark jet is more collimated.

    hep-phEPJC(2022)·11 citations
23. 23*

    Coalescence, the thermal model and multi-fragmentation: The energy and volume dependence of light nuclei production in heavy ion collisions

    Paula Hillmann🇩🇪 · Katharina Käfer🇩🇪 · Jan Steinheimer🇩🇪 · Volodymyr Vovchenko🇺🇸 · Marcus Bleicher🇩🇪

    We present results of a phase space coalescence approach within the UrQMD transport and -hybrid model for a very wide range of beam energies from SIS to LHC. The coalescence model is able to qualitatively describe the whole range of experimental data with a fixed set of parameters. Some systematic deviations are observed for very low beam energies where the role of feed down from heavier nuclei and multi-fragmentation becomes relevant. The coalescence results are mostly very close to the thermal model fits. However, both the coalescence approach as well as thermal fits are struggling to simultaneously describe the triton multiplicities measured with the STAR and ALICE experiment. The double ratio of $tp/d^2$, in the coalescence approach, is found to be essentially energy and centrality independent for collisions of heavy nuclei at beam energies of ${\mathrm{E}}_{\mathrm{lab}}>10A$ GeV. On the other hand the clear scaling of the $d/p^2$ and $t/p^3$ ratios with the systems volume is broken for peripheral collisions, where a canonical treatment and finite size effects become more important.

    hep-phnucl-thJ.Phys.G(2022)·40 citations
24. 24*

    Discovering heavy neutrino oscillations in rare Bc meson decays at HL-LHCb

    Sebastian Tapia (1)🇺🇸 · Marcelo Vidal-Bravo (2 and 3)🇨🇱 · Jilberto Zamora-Saa (2 and 3) ((1) Department of Physics and Astronomy, Iowa State University, USA, (2) Center for Theoretical and Experimental Particle Physics, Facultad de Ciencias Exactas, Universidad Andres Bello, Chile, (3) Millennium Institute for Subatomic physics at high energy frontier - SAPHIR, Santiago, Chile)🇨🇱

    In this work, we study the lepton flavor and lepton number violating $B_c$ meson decays via two intermediate on-shell Majorana neutrinos $N_j$ into two charged leptons and a charged pion $B_c^{\pm }\to {\mu }^{\pm }{N}_j\to {\mu }^{\pm }{\tau }^{\pm }{\pi }^{\mp }$. We evaluated the possibility to measure the modulation of the decay width along the detector length produced as a consequence of the lepton flavor violating process, in a scenario where the heavy neutrinos masses range between $2.0$ GeV $\le M_N\le 6.0$ GeV. We study some realistic conditions which could lead to the observation of this phenomenon at futures $B$ factories such HL-LHCb.

    hep-phPRD(2022)·9 citations
25. 25*

    Unveiling Hidden Physics at the LHC

    Oliver Fischer🇬🇧 · Bruce Mellado🇿🇦 · Stefan Antusch🇨🇭 · Emanuele Bagnaschi🇨🇭 · Shankha Banerjee🇨🇭 · Geoff Beck🇿🇦 · Benedetta Belfatto🇮🇹 · Matthew Bellis🇺🇸 · Zurab Berezhiani🇮🇹 · Monika Blanke🇩🇪 · Bernat Capdevila🇮🇹 · Kingman Cheung🇹🇼 and 21 other authors

    The field of particle physics is at the crossroads. The discovery of a Higgs-like boson completed the Standard Model (SM), but the lacking observation of convincing resonances Beyond the SM (BSM) offers no guidance for the future of particle physics. On the other hand, the motivation for New Physics has not diminished and is, in fact, reinforced by several striking anomalous results in many experiments. Here we summarise the status of the most significant anomalies, including the most recent results for the flavour anomalies, the multi-lepton anomalies at the LHC, the Higgs-like excess at around 96 GeV, and anomalies in neutrino physics, astrophysics, cosmology, and cosmic rays. While the LHC promises up to 4/ab of integrated luminosity and far-reaching physics programmes to unveil BSM physics, we consider the possibility that the latter could be tested with present data, but that systemic shortcomings of the experiments and their search strategies may preclude their discovery for several reasons, including: final states consisting in soft particles only, associated production processes, QCD-like final states, close-by SM resonances, and SUSY scenarios where no missing energy is produced. New search strategies could help to unveil the hidden BSM signatures, devised by making use of the CERN open data as a new testing ground. We discuss the CERN open data with its policies, challenges, and potential usefulness for the community. We showcase the example of the CMS collaboration, which is the only collaboration regularly releasing some of its data. We find it important to stress that individuals using public data for their own research does not imply competition with experimental efforts, but rather provides unique opportunities to give guidance for further BSM searches by the collaborations. Wide access to open data is paramount to fully exploit the LHCs potential.

    hep-phhep-exEPJC(2022)·90 citations
26. 26*

    An explanation of experimental data of $(g-2{)}_{e,\mu }$ in 3-3-1 models with inverse seesaw neutrinos

    L. T. Hue🇻🇳 · Khiem Hong Phan🇻🇳 · T. Phong Nguyen🇻🇳 · H. N. Long🇻🇳 · H. T. Hung🇻🇳

    We show that the anomalous magnetic moment experimental data of muon and electron $(g-2{)}_{\mu ,e}$ can be explained simultaneously in simple extensions of the 3-3-1 models consisting of new heavy neutrinos and a singly charged Higgs boson. The heavy neutrinos generate active neutrino masses and mixing through the general seesaw mechanism. They also have non-zero Yukawa couplings with singly charged Higgs bosons and right-handed charged leptons, which result in large one-loop contributions known as \emph{chirally-enhanced} ones. Numerical investigation confirms a conclusion indicated previously that these contributions are the key point to explain the large $(g-2{)}_{\mu ,e}$ data, provided that the inverse seesaw mechanism is necessary to allow both conditions that heavy neutrino masses are above few hundred GeV and non-unitary part of the active neutrino mixing matrix must be large enough.

    hep-phEPJC(2022)·20 citations
27. 27*

    Bound-Free Pair Production Mechanism at the NICA Accelerator Complex

    Melek Yilmaz Şengül🇹🇷

    In this work, bound-free pair production (BFPP) cross section calculations are done for NICA collider. In the BFPP mechanisms, after free pair production process, free electron is captured by one of the ions. This causes to the decrement of the ion from the beam, also diminish the intensity of the beam and changes the beam lifetime. BFPP cross section calculations are done for p-Au and p-Bi collisions for NICA collider and it is seen that the obtained results are in the range of a few mbarns. In this work, we used the lowest-order perturbation theory and our calculations are done in QED framework.

    hep-phActa Phys.Polon.B(2021)·1 citation
28. 28*

    Production of vector mesons in the String+${}^3{P}_0$ model of polarized quark fragmentation

    A. Kerbizi🇮🇹 · X. Artru🇫🇷 · A. Martin🇮🇹

    The production of vector mesons in the fragmentation process of polarized quarks is studied within the recursive String+${}^3{P}_0$ model, improving a previous version of the model in which the production of pseudoscalar mesons only was considered. Two types of couplings of the vector meson to quarks are introduced, their coupling constants being the additional free parameters of the model. The angular distribution of the decay products of the polarized vector meson is deduced from the spin density matrix of the meson and the spin information is propagated along the fragmentation chain taking into account the entanglement of spin states. The new model is implemented in a stand alone Monte Carlo program utilized to investigate in detail kinematic distributions and transverse spin asymmetries. The sensitivity of these observables to the new free parameters is discussed and the Monte Carlo results are compared with experimental data on transverse spin asymmetries.

    hep-phPRD(2021)·21 citations
29. 29*

    B-Anomalies from flavorful U(1)' extensions, safely

    Rigo Bause🇩🇪 · Gudrun Hiller🇩🇪 · Tim Höhne🇩🇪 · Daniel F. Litim🇬🇧 · Tom Steudtner🇩🇪

    $U(1{)}^{\prime }$ extensions of the standard model with generation-dependent couplings to quarks and leptons are investigated as an explanation of anomalies in rare $B$-decays, with an emphasis on stability and predictivity up to the Planck scale. To these ends, we introduce three generations of vector-like standard model singlet fermions, an enlarged, flavorful scalar sector, and, possibly, right-handed neutrinos, all suitably charged under the $U(1{)}^{\prime }$ gauge interaction. We identify several gauge-anomaly free benchmarks consistent with $B_s$-mixing constraints, with hints for electron-muon universality violation, and the global $b\to s$ fit. We further investigate the complete two-loop running of gauge, Yukawa and quartic couplings up to the Planck scale to constrain low-energy parameters and enhance the predictive power. A characteristic of models is that the $Z^{\prime }$ with TeV-ish mass predominantly decays to invisibles, i.e. new fermions or neutrinos. $Z^{\prime }$-production can be studied at a future muon collider. While benchmarks feature predominantly left-handed couplings $C_9^{\mu }$ and $C_{10}^{\mu }$, right-handed ones can be accommodated as well.

    hep-phEPJC(2022)·47 citations
30. 30*

    Off-of-equilibrium effects on Kurtosis Along Strangeness-Neutral Trajectories

    Travis Dore🇺🇸 · Jamie Karthein🇺🇸 · Debora Mroczek🇺🇸 · Paolo Parotto🇩🇪 · Jacquelyn Noronha-Hostler🇺🇸 · Claudia Ratti🇺🇸

    The Beam Energy Scan program at the Relativistic Heavy Ion Collider (RHIC) is searching for the QCD critical point. The main signal for the critical point is the kurtosis of the distribution of proton yields obtained on an event-by-event basis where one expects a peak at the critical point. However, its exact behavior is still an open question due to out-of-equilibrium effects and uncertainty in the equation of state. Here we use a simplistic hydrodynamic model that enforces strangeness-neutrality, selecting trajectories that pass close to the critical point. We vary the initial conditions to estimate the effect of out-of-equilibrium hydrodynamics on the kurtosis signal.

    ↳ nucl-thhep-phnucl-exEPJ Web Conf.(2022)·4 citations
31. 31*

    Improved DHOST Genesis

    Mian Zhu🇨🇳 · Yunlong Zheng🇨🇳

    We improve the DHOST Genesis proposed in \cite{Ilyas:2020zcb}, such that the near scale invariant scalar power spectrum can be generated from the model itself, without involking extra mechanism like a string gas. Besides, the superluminality problem of scalar perturbation plagued in \cite{Ilyas:2020zcb} can be rescued by choosing proper DHOST action.

    ↳ gr-qcastro-ph.COhep-phhep-thJHEP(2021)·26 citations
32. 32*

    Novel way to construct spatially localized finite energy structures

    D. Bazeia🇧🇷 · M.A. Marques🇧🇷 · M. Paganelly🇧🇷

    In this work we introduce a procedure to find localized structures with finite energy. We start dealing with global monopoles, and add a new contribution to the potential of the scalar fields, to balance the contribution of the angular gradients of the fields which lead to a slow falloff in the energy density. Within the first order formalism, first order equations that are compatible with the equations of motion are obtained and the stability under small fluctuations is investigated. We then include another set of scalar fields and study how it contributes to change the profile of the localized structure. We also study how these configurations modify the electric properties of a system with a single point charge, with generalized electric permittivity controlled by scalar fields. In this new model, in particular, we show that, depending on the specific modification of the electric properties of the medium, the electric field may engender the unusual behavior of pointing towards a positive charge.

    ↳ hep-thhep-phEur.Phys.J.Plus(2021)·4 citations
33. 33*

    Enhancement of electron-positron pairs in combined potential wells with linear chirp frequency

    Li Wang🇨🇳 · Lie-Juan Li🇨🇳 · Melike Mohamedsedik🇨🇳 · Rong An🇨🇳 · Jing-Jing Li🇨🇳 · Bai-Song Xie🇨🇳 · Feng-Shou Zhang🇨🇳

    The effect of linear chirp frequency on the process of electron-positron pairs production from vacuum in the combined potential wells is investigated by computational quantum field theory. Numerical results of electron number and energy spectrum under different frequency modulation parameters are obtained. By comparing with the fixed frequency, it is found that frequency modulation has a significant enhancement effect on the number of electrons. Especially when the frequency is small, appropriate frequency modulation enhances multiphoton processes in pair creation, thus promoting the pair creation. However, the number of electrons created by high frequency oscillating combined potential wells decreases after frequency modulation due to the phenomenon of high frequency suppression. The contours of the number of electrons varying with frequency and frequency modulation parameters are given, which may provide theoretical reference for possible experiments.

    ↳ quant-phhep-phChin.Phys.B(2023)·9 citations
34. 34*

    Boson Stars and Oscillatons: A Review

    Luca Visinelli🇮🇹

    Compact objects occupy a pivotal role in the exploration of Nature. The interest spans from the role of compact objects in astrophysics to their detection through various methods (gravitational waves interferometry, microlensing, imaging). While the existence of compact objects made of fermions (neutron stars and white dwarfs) has been assessed, a parallel search for localized solitons made of bosons is ongoing, stemming from Wheeler's original proposal of electromagnetic "geons". Boson fields can clump up and form compact objects such as boson stars (for complex scalar fields), oscillons and oscillatons (for real scalar fields), or Proca stars (for massive vector fields), which can show up in searches as black hole mimickers, dark matter sources, and a variety of other phenomena. I review some crucial properties of these bosonic systems, including recent progress in the field.

    ↳ gr-qchep-phInt.J.Mod.Phys.D(2021)·148 citations
35. 35*

    Entropy and Black Holes in the Very Early Universe

    Tom Banks🇺🇸 · Willy Fischler🇺🇸

    Model independent arguments following from the Covariant Entropy Principle imply that causal diamonds in the very early universe were entirely filled with a single equilibrated system with finite entropy. A universe where this condition persists forever has no localized excitations. Our own universe appears to be headed toward such a state. Within a few hundred times its current age it will approach a state where our local group of galaxies sit in empty de Sitter space. Eventually, the local group collapse into a black hole, which evaporates. Localized excitations in de Sitter space are low entropy constrained states of the vacuum ensemble. The origin of these constraints must be in the early universe: the apparent horizon must expand after some initial period, in a constrained state that is the origin of all localized excitations in the universe. We argue that in global FRW coordinates, this corresponds to slow roll inflation that ends in a dilute gas of tiny black holes, with mass determined by the inflationary scale. We then review arguments that these black holes can account for the Hot Big Bang, baryogenesis, a distinctive pattern of CMB fluctuations, and possibly primordial black hole dark matter consisting of larger black holes that survive until the matter dominated era. The more complicated question of whether these small black holes can evolve in a way that is consistent with all observational constraints requires computer simulations that have not yet been done.

    ↳ hep-thgr-qchep-ph8 citations
36. 36*

    Cosmological search for sterile neutrinos after Planck 2018

    Lu Feng🇨🇳 · Rui-Yun Guo🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳

    Sterile neutrinos can affect the evolution of the universe, and thus using the cosmological observations can search for sterile neutrinos. In this work, we use the cosmic microwave background (CMB) anisotropy data from the Planck 2018 release, combined with the latest baryon acoustic oscillation (BAO), type Ia supernova (SN), and Hubble constant ($H_0$) data, to constrain the cosmological models with considering sterile neutrinos. In order to test the influences of the properties of dark energy on the {results} of searching for sterile neutrinos, in addition to the $\Lambda$ cold dark matter ($\Lambda$CDM) model, we also consider the $w$CDM model and the holographic dark energy (HDE) model. We find that the existence of sterile neutrinos {is not preferred} when the $H_0$ local measurement is not included in the data combination. When the $H_0$ measurement is included in the joint constraints, it is found that $\Delta N_{\mathrm{eff}}>0$ is {favored} at about 2.7$\sigma$ level for the $\Lambda$CDM model and at about 1-1.7$\sigma$ level for the $w$CDM model. However, $m_{\nu ,\mathrm{sterile}}^{\mathrm{eff}}$ still cannot be well constrained and only upper limits can be given. In addition, we find that the HDE model is definitely ruled out by the current data. We also discuss the issue of the Hubble tension, and we conclude that involving sterile neutrinos in the cosmological models cannot truly resolve the Hubble tension.

    ↳ astro-ph.COgr-qchep-phPLB(2022)·23 citations
37. 37*

    Construction of Wave Dark Matter Halos: Numerical Algorithm and Analytical Constraints

    Tomer D. Yavetz🇺🇸 · Xinyu Li🇨🇦 · Lam Hui🇺🇸

    We present a wave generalization of the classic Schwarzschild method for constructing self-consistent halos -- such a halo consists of a suitable superposition of waves instead of particle orbits, chosen to yield a desired mean density profile. As an illustration, the method is applied to spherically symmetric halos. We derive an analytic relation between the particle distribution function and the wave superposition amplitudes, and show how it simplifies in the high energy (WKB) limit. We verify the stability of such constructed halos by numerically evolving the Schrödinger-Poisson system. The algorithm provides an efficient and accurate way to simulate the time-dependent halo substructures from wave interference. We use this method to construct halos with a variety of density profiles, all of which have a core from the ground-state wave function, though the core-halo relation need not be the standard one.

    ↳ astro-ph.COastro-ph.GAgr-qchep-phPRD(2022)·76 citations
38. 38*

    Neutrino Emissivities as a Probe of the Internal Magnetic Fields of White Dwarfs

    Marco Drewes🇧🇪 · Jamie McDonald🇧🇪 · Loïc Sablon🇧🇪 · Edoardo Vitagliano🇺🇸

    The evolution of white dwarfs (WDs) depends crucially on thermal processes. The plasma in their core can produce neutrinos which escape from the star, thus contributing to the energy loss. While in absence of a magnetic field the main cooling mechanism is plasmon decay at high temperature and photon surface emission at low temperature, a large magnetic field in the core hiding beneath the surface even of ordinary WDs, and undetectable to spectropolarimetric measurements, can potentially leave an imprint in the cooling. In this paper, we revisit the contribution to WD cooling stemming from neutrino pair synchrotron radiation and the effects of the magnetic field on plasmon decay. Our key finding is that even if observations limit the magnetic field strength at the stellar surface, magnetic fields in the interior of WDs -- with or without a surface magnetic field -- can be strong enough to modify the cooling rate, with neutrino pair synchrotron emission being the most important contribution. This effect may not only be relevant for the quantification and interpretation of cooling anomalies, but also suggests that the internal magnetic fields of WDs should be smaller than $\sim 6\times 10^{11}\mathrm{G}$, slightly improving bounds coming from a stability requirement. While our simplified treatment of the WD structure implies that further studies are needed to reduce the systematic uncertainties, the estimates based on comparing the emissivities illustrate the potential of neutrino emission as a diagnostic tool to study the interior of WDs.

    ↳ astro-ph.SRastro-ph.HEhep-phApJ(2022)·17 citations
39. 39*

    RG of GR from On-shell Amplitudes

    Pietro Baratella🇩🇪 · Dominik Haslehner🇩🇪 · Maximilian Ruhdorfer🇺🇸 · Javi Serra🇩🇪 · Andreas Weiler🇩🇪

    We study the renormalization group of generic effective field theories that include gravity. We follow the on-shell amplitude approach, which provides a simple and efficient method to extract anomalous dimensions avoiding complications from gauge redundancies. As an invaluable tool we introduce a modified helicity $\tilde{h}$ under which gravitons carry one unit instead of two. With this modified helicity we easily explain old and uncover new non-renormalization theorems for theories including gravitons. We provide complete results for the one-loop gravitational renormalization of a generic minimally coupled gauge theory with scalars and fermions and all orders in $M_{Pl}$, as well as for the renormalization of dimension-six operators including at least one graviton, all up to four external particles.

    ↳ hep-thgr-qchep-phJHEP(2022)·30 citations
40. 40*

    Bound on Induced Gravitational Waves during Inflation Era

    Keisuke Inomata🇺🇸

    We put the upper bound on the gravitational waves (GWs) induced by the scalar-field fluctuations during the inflation. In particular, we focus on the case where the scalar fluctuations get amplified within some subhorizon scales by some mechanism during the inflation. Since the energy conservation law leads to the upper bound on the energy density of the scalar fluctuations, the amplitudes of the scalar fluctuations are constrained and therefore the induced GWs are also. Taking into account this, we derive the upper bound on the induced GWs. As a result, we find that the GW power spectrum must be ${\mathcal{P}}_h\lesssim \mathcal{O}({ϵ}^2(k/k_{\ast }{)}^2)$ up to the logarithmic factor, where $ϵ$ is the slow-roll parameter and $k_{\ast }$ is the peak scale of the scalar-field fluctuations.

    ↳ astro-ph.COgr-qchep-phPRD(2021)·28 citations
41. 41*

    Two-Sheeted Universe, Analyticity and the Arrow of Time

    Latham Boyle🇨🇦 · Neil Turok🇨🇦

    Our universe seems to be radiation dominated at early times, and vacuum energy dominated at late times. When we consider the maximal analytic extension of this spacetime, its symmetries and complex analytic properties suggest a picture in which spacetime has two sheets, exchanged by an isometry which, in turn, picks a preferred (CPT-symmetric) vacuum state for quantum fields on the spacetime. Previously (arXiv:1803.08928, arXiv:1803.08930), we showed how this line of thought provides new explanations for dark matter, the matter-antimatter asymmetry, the absence of primordial vector and tensor perturbations, and the {\it phase} of the primordial scalar perturbations; and additional testable predictions. In this paper, we develop this picture in several respects and, in particular, point out that it also provides a new explanation for why the thermodynamic arrow of time points away from the bang.

    ↳ hep-thastro-ph.COgr-qchep-ph34 citations
42. 42*

    Turn up the volume: Listening to phase transitions in hot dark sectors

    Fatih Ertas🇩🇪 · Felix Kahlhoefer🇩🇪 · Carlo Tasillo🇩🇪

    Stochastic gravitational wave (GW) backgrounds from first-order phase transitions are an exciting target for future GW observatories and may enable us to study dark sectors with very weak couplings to the Standard Model. In this work we show that such signals may be significantly enhanced for hot dark sectors with a temperature larger than the one of the SM thermal bath. The need to transfer the entropy from the dark sector to the SM after the phase transition can however lead to a substantial dilution of the GW signal. We study this dilution in detail, including the effect of number-changing processes in the dark sector (so-called cannibalism), and show that in large regions of parameter space a net enhancement remains. We apply our findings to a specific example of a dark sector containing a dark Higgs boson and a dark photon and find excellent detection prospects for LISA and the Einstein telescope.

    ↳ astro-ph.COhep-phJCAP(2022)·60 citations
43. 43*

    Possible uses of the binary icosahedral group in grand unified theories

    Robert A. Wilson🇬🇧

    There are exactly three finite subgroups of SU(2) that act irreducibly in the spin 1 representation, namely the binary tetrahedral, binary octahedral and binary icosahedral groups. In previous papers I have shown how the binary tetrahedral group gives rise to all the necessary ingredients for a non-relativistic model of quantum mechanics and elementary particles, and how a modification of the binary octahedral group extends this to the ingredients of a relativistic model. Here I investigate the possibility that the binary icosahedral group might be related in a similar way to grand unified theories such as the Georgi--Glashow model, the Pati--Salam model, various $E_8$ models and perhaps even M-theory. This analysis suggests a possible way to combine the best parts of all these models into a new model that goes further than any of them individually. The key point is to separate the Dirac spinor into two separate concepts, one of which is Lorentz-covariant, and the other Lorentz-invariant. This produces a model which does not have a CPT-symmetry, and therefore supports an asymmetry between particles and antiparticles. The Lagrangian has four terms, and there is a gauge group GL(4,R) which permits the terms to be separated in an arbitrary way, so that the model is generally covariant. Quantum gravity in this model turns out to be described by quite a different gauge group, namely SO(5), acting on a 5-dimensional space that behaves like a spin 2 representation after suitable symmetry-breaking. I then use this proposed model to make a few predictions and postdictions, and compare the results with experiment.

    ↳ physics.gen-phhep-ph7 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.