Tue·May 12, 2020Tuesday·May 12, 2020

1. 01*

   Combined explanations of $(g-2{)}_{\mu }$, $R_{D^{(\ast )}}$, $R_{K^{(\ast )}}$ anomalies in a two-loop radiative neutrino mass model

   Shaikh Saad🇺🇸

   Motivated by the long-standing tension in the muon anomalous magnetic moment (AMM) and persistent observations of B-physics anomalies in $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$ ratios, we construct a simple two-loop radiative neutrino mass model, and propose a combined explanations of all these apparently disjoint phenomena within this framework. Our proposed model consists of two scalar leptoquarks (LQs), a $SU(2{)}_L$ singlet $S_1\sim (\overline{3},1,1/3)$ and a $SU(2{)}_L$ triplet $S_3\sim (\overline{3},3,1/3)$ to accommodate $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$ anomalies, respectively. The muon receives chirality-enhanced contribution towards its $g-2$ due to the presence of $S_1$ LQ that accounts for the observed deviation from the Standard Model prediction. Furthermore, we introduce a $SU(2{)}_L$ singlet scalar diquark $\omega \sim (\overline{6},1,2/3)$, which is necessary to break lepton number and generate neutrino mass radiatively with the aid of $S_1$ and $S_3$ LQs. We perform a detailed phenomenological analysis of this set-up and demonstrate its viability by providing benchmark points where a fit to the neutrino oscillation data together with proper explanations of the muon AMM puzzle and flavor anomalies are accomplished while simultaneously meeting all other flavor violation and collider bounds.

   hep-phPRD(2020)·97 citations
2. 02*

   Non-perturbative Enhancement of Heavy Quark-Antiquark Pair Annihilation in the Quark-Gluon Plasma

   Xin Wu🇨🇳 · Min He🇨🇳

   The annihilation of heavy particles close to thermal equilibrium, which plays a prominent role in the chemical equilibration of heavy quarks in the Quark-Gluon Plasma (QGP) as well as in many classic dark matter scenarios, is reexamined. We derive a scattering amplitude that resums near-threshold attractive interaction of the annihilating particles in terms of the non-relativistic scattering $T$-matrix and Green's function, thereby capturing the pertinent Sommerfeld enhancement from both nonperturbative scattering state and bound state solutions. The derived formula is of such generality that it applies to arbitrary partial wave processes of two-particle annihilation, and enables to incorporate finite widths of the annihilating particles. In a screened potential model, the non-perturbative scattering amplitude is computed and the Sommerfeld enhancement is identified for heavy quark-antiquark annihilation in the QGP.

   hep-phnucl-exnucl-thPRD(2020)·0 citations
3. 03*

   Two-body light front wave functions from general AdS/QCD models

   Alfredo Vega🇨🇱 · Miguel Angel Martin Contreras🇨🇱

   In this work, we consider an extension to the matching procedure proposed by Brodsky and de Teramond to obtain the two-body wave functions in the light-front formalism for holographic models. We compute the light-front wave function (LFWF) considering different static dilaton fields and AdS-like geometric deformations. We also prove that this procedure holds for general AdS/QCD models in asymptotically AdS geometries.

   hep-phPRD(2020)·5 citations
4. 04*

   Resonance enhancement of neutrino oscillations due to transition magnetic moments

   A. V. Chukhnova🇷🇺 · A. E. Lobanov🇷🇺

   We prove that a resonance enhancement of neutrino oscillations in magnetic field is possible due to transition magnetic moments and demonstrate that this resonance is strictly connected to the neutrino polarization. To study the main properties of this resonance, we obtain the probabilities of transitions between neutrino states with definite flavor and helicity in inhomogeneous electromagnetic field in the adiabatic approximation. Since the resonance is present only when the adiabaticity condition is fulfilled, we also obtain and discuss this condition.

   hep-phhep-thEPJC(2021)·12 citations
5. 05*

   Improved strong coupling determinations from hadronic decays of electroweak bosons at N${}^3$LO accuracy

   David d'Enterria🇨🇭 · Villads Jacobsen🇩🇰

   We present two new extractions of the QCD coupling constant at the Z pole, ${\alpha }_S(m_Z)$, from detailed comparisons of inclusive W and Z hadronic decays data to state-of-the-art perturbative Quantum Chromodynamics calculations at next-to-next-to-next-to-leading order (N${}^3$LO) accuracy, incorporating the latest experimental and theoretical developments. In the W boson case, the total width computed at N${}^3$LO is used for the first time in the extraction. For the Z boson pseudo-observables, the N${}^3$LO results are complemented with the full two- and partial three-loop electroweak corrections recently made available, and the experimental values are updated to account for newly estimated LEP luminosity biases. A combined reanalysis of the Z boson data yields ${\alpha }_S(m_Z)=0.1203\pm 0.0028$, with a 2.3\% uncertainty reduced by about 7\% compared to the previous state-of-the-art. From the combined W boson data, a value of ${\alpha }_S(m_Z)=0.101\pm 0.027$ is extracted, with still large experimental uncertainties but also reduced compared to previous works. The levels of theoretical and parametric precision required in the context of QCD coupling determinations with permil uncertainties from high-statistics W and Z boson samples expected at future $e^{+}{e}^{-}$ colliders such as the FCC-ee, are discussed in detail.

   hep-phhep-ex38 citations
6. 06*

   Dense Baryonic Matter and Applications of QCD Phase Diagram Dualities

   T. G. Khunjua🇬🇪 · K. G. Klimenko🇷🇺 · R. N. Zhokhov🇷🇺

   Recently it has been found that quantum chromodynamics (QCD) phase diagram possesses a duality between chiral symmetry breaking and pion condensation. For the first time this was revealed in the QCD motivated toy model. Then it was demonstrated in effective models as well and new additional dualities being found. We briefly recap the main features of this story and then discuss its applications as a tool to explore the QCD phase structure. The most appealing application is the possibility of getting the results on the QCD phase diagram at large baryon density. Taking the idea from large $1/N_c$ universalities it was argued that the scenario of circumventing the sign problem with the help of dualities seems plausible. It is also discussed that there is a persistent problem about whether there should be catalysis or anti-catalysis of chiral symmetry breaking by chiral imbalance. One can probably say that the issue is settled after lattice results (first principle approach), where the catalysis was observed. But they used an unphysically large pion mass so it is still interesting to get additional indications that this is the case. It is shown just by the duality property that there exists catalysis of chiral symmetry breaking. So, having in mind our results and the earlier lattice simulations, one can probably claim that this issue is settled. It is demonstrated that the duality can be used to obtain new results. As an example, it is showcased how the phase structure of dense quark matter with chiral imbalance (with possibility of inhomogeneous phases) can be obtained from the knowledge of a QCD phase diagram with isopin asymmetry.

   hep-phhep-thnucl-thParticles(2020)·14 citations
7. 07*

   Dense baryonic matter with chiral imbalance and charged pion condensation

   T. G. Khunjua🇬🇪 · K. G. Klimenko🇷🇺 · R. N. Zhokhov🇷🇺

   After the first predictions in seventies that in dense nuclear matter, for example, in neutron stars there could be pion condensation phenomenon, it was shown that at least s-wave pion condensation is unlikely to occur in such a medium in different approaches including NJL model consideration with neutrality and $\beta$-equilibrium condition. Then it has been found a condition that can promote this phenomenon in dense baryonic matter, it is chiral imbalance, so now it is interesting if this generation can survive rather strict requirement of electric neutrality and $\beta$-equilibrium. Here in this paper the generation of pion condensation in dense baryonic matter by chiral imbalance is investigated. It is shown that electric neutrality and $\beta$-equilibrium conditions do not spoil this phenomenon and this leads to interesting applications for physics of neutron stars. There are several possible mechanisms of generation of chiral imbalance in dense matter. In a view of latest and forthcoming NICER results and the first observed and possibly new events of neutron star mergers it is rather interesting to explore how possible chiral imbalance in neutron star can influence and change EOS and, hence, mass-radius relation. It is a first step in that direction.

   hep-phhep-thnucl-thActa Phys.Polon.Supp.(2021)·8 citations
8. 08*

   Evasion of HSR in the charmless decays of excited $P$-wave charmonia

   Yan Wang🇨🇳 · Qi Wu🇨🇳 · Gang Li🇨🇳 · Ju-Jun Xie🇨🇳 · Chun-Sheng An🇨🇳

   We investigate the charmless decays of excited $P$-wave charmonia ${\chi }_{c1}^{\prime }\to VV$ and ${\chi }_{c2}^{\prime }\to VP$ via intermediate charmed meson loops, where $V$ and $P$ denote the light vector and pseudoscalar mesons, respectively. Within the model parameters, the charmed meson loop contributions are evaluated by using the effective Lagrangian approach. For ${\chi }_{c1}^{\prime }\to VV$, the partial widths of the $\rho \rho$, $\omega \omega$, and $K^{\ast }{\bar{K}}^{\ast }$ channels can reach to the order of MeV, while the partial width of the $\varphi \varphi$ channel is very small and in the order of keV. For ${\chi }_{c2}^{\prime }\to VP$, the partial widths of ${\chi }_{c2}^{\prime }\to K^{\ast }\bar{K}+c.c$ turns out to be sizeable, while the partial widths of ${\chi }_{c2}^{\prime }\to {\rho }^{+}{\pi }^{-}+c.c$ is found to be much smaller than the $K^{\ast }\bar{K}+c.c$ channel. Our calculations may be examined by the future BESIII experiments.

   hep-phEPJC(2020)·4 citations
9. 09*

   One-loop electroweak radiative corrections to lepton pair production in polarized electron-positron collisions

   S. Bondarenko (1)🇷🇺 · Ya. Dydyshka (2)🇷🇺 · L. Kalinovskaya (2)🇷🇺 · R. Sadykov (2)🇷🇺 · V. Yermolchyk (2) ((1) Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna, Russia (2) Dzhelepov Laboratory of Nuclear Problems, JINR, Dubna, Russia)🇷🇺

   This paper presents the high-precision theoretical predictions for $e^{+}{e}^{-}\to l^{-}{l}^{+}$ scattering. Calculations are performed using the {\tt SANC} system. They take into account complete one-loop electroweak radiative corrections as well as longitudinal polarization of initial beams. Reaction observables are obtained using the helicity amplitude method with taking into account initial and final state fermion masses. Numerical results are given for the center-of-mass energy range $\sqrt{s}=250-1000$ GeV with various degrees of polarization.

   hep-phPRD(2020)·8 citations
10. 10*

    The production of excited states of doubly heavy baryons at the Large Hadron Collider

    A. V. Berezhnoy🇷🇺 · I. N. Belov🇷🇺 · A. K. Likhoded🇷🇺

    In the framework of diquark model for production we discuss the yields and observation prospects for excited states of doubly heavy baryons at LHC kinematic conditions.

    hep-phPhys.Atom.Nucl.(2020)·4 citations
11. 11*

    Hunting for possible Higgs-like boson beyond the Standard Model

    Xing-Dao Guo🇨🇳 · Jian-Wen Zhu🇨🇳 · Ren-You Zhang🇨🇳 · Shu-Min Zhao🇨🇳 · Wen-Gan Ma🇨🇳 · Xue-Qian Li🇨🇳

    A recent preliminary investigation based on Durgut's report at the American Physical Society site shows a structure at $18.4\mathrm{GeV}$ exists in the invariant mass distribution of ${\rm Y}{l}^{+}{l}^{-}(l=e,\mu )$ at the LHC center-of-mass energy of $7$ and $8\mathrm{TeV}$. Its appearance attracts attention of theorists and experimentalists of high energy physics, because it might be a Higgs-like boson of $18.4\mathrm{GeV}$ which would serve as a signal of the new physics beyond the Standard Model. We have carried out computations on the corresponding quantities (production and decay rates) based on quantum field theory and compared the results with experimental data. Our numerical results do not support the assertion that the $18.4\mathrm{GeV}$ peak corresponds to a neutral $0^{++}$ boson which decays into ${\rm Y}{l}^{+}{l}^{-}$. Much further works (both experimental and theoretical) are badly needed.

    hep-phPRD(2020)·1 citation
12. 12*

    Nonlinear susceptibilities of heavy ion collisions within the Polyakov-loop-extended Nambu-Jona-Lasinio model

    Songju Lei🇨🇳 · Runlin Liu🇨🇳

    The baryon-number susceptibilities is correlated to the fluctuations obtained in experiments, we can theoretically calculate the susceptibility and compare it with the experimental fluctuations data. In this paper, we calculate the baryon-number susceptibilities from the Polyakov-loop-extended Nambu-Jona-Lasinio (PNJL) model, then compare them with the the heavy ion collision experimental fluctuation data and the results from other models, lattice QCD and the Dyson-Schwinger equations (DSEs) approach. Our results are in line with the experiment and very similar to the results of DSEs at experimental points, which shows that the PNJL model is suitable for studying this issue.

    hep-ph0 citations
13. 13*

    Excitation function of initial temperature of heavy flavor quarkonium emission source in high energy collisions

    Qi Wang🇨🇳 · Fu-Hu Liu🇨🇳

    The transverse momentum spectra of $J/\psi$, $\psi (2S)$, and ${\rm Y}(nS,n=1,2,3)$ produced in proton-proton ($p$+$p$), proton-antiproton ($p$+$\bar{p}$), proton-lead ($p$+Pb), gold-gold (Au+Au), and lead-lead (Pb+Pb) collisions over a wide energy range are analyzed by the (two-component) Erlang distribution, the Hagedorn function (the inverse power-law), and the Tsallis-Levy function. The initial temperature is obtained from the color string percolation model due to the fit by the (two-component) Erlang distribution in the framework of multisource thermal model. The excitation functions of some parameters such as the mean transverse momentum and initial temperature increase from dozens of GeV to above 10 TeV. The mean transverse momentum and initial temperature decrease (increase slightly or do not change obviously) with the increase of rapidity (centrality). Meanwhile, the mean transverse momentum of ${\rm Y}(nS,n=1,2,3)$ is larger than that of $J/\psi$ and $\psi (2S)$, and the initial temperature for ${\rm Y}(nS,n=1,2,3)$ emission is higher than that for $J/\psi$ and $\psi (2S)$ emission, which shows a mass-dependent behavior.

    hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2020)·10 citations
14. 14*

    Determination of the top-quark $\overline{\mathrm{MS}}$ running mass via its perturbative relation to the on-shell mass with the help of principle of maximum conformality

    Xu-Dong Huang🇨🇳 · Xing-Gang Wu🇨🇳 · Jun Zeng🇨🇳 · Qing Yu🇨🇳 · Xu-Chang Zheng🇨🇳 · Shuai Xu🇨🇳

    In the paper, we study the properties of the top-quark $\overline{\mathrm{MS}}$ running mass computed from its on-shell mass by using both the four-loop $\overline{\mathrm{MS}}$-on-shell relation and the principle of maximum conformality (PMC) scale-setting approach. The PMC adopts the renormalization group equation to set the correct magnitude of the strong running coupling of the perturbative series, its prediction avoids the conventional renormalization scale ambiguity, and thus a more precise pQCD prediction can be achieved. After applying the PMC to the four-loop $\overline{\mathrm{MS}}$-on-shell relation and taking the top-quark on-shell mass $M_t=172.9\pm 0.4$ GeV as an input, we obtain the renormalization scale-invariant $\overline{\mathrm{MS}}$ running mass at the scale $m_t$, e.g., $m_t(m_t)\simeq 162.6\pm 0.4$ GeV, in which the error is the squared average of those from $\Delta {\alpha }_s(M_Z)$, $\Delta M_t$, and the approximate error from the uncalculated five-loop terms predicted by using the Padé approximation approach.

    hep-phPRD(2020)·11 citations
15. 15*

    Magnetic monopoles revisited: Models and searches at colliders and in the Cosmos

    Nick E. Mavromatos🇬🇧 · Vasiliki A. Mitsou🇪🇸

    In this review, we discuss recent developments in both the theory and the experimental searches of magnetic monopoles in past, current and future colliders and in the Cosmos. The theoretical models include, apart from the standard Grand Unified Theories, extensions of the Standard Model that admit magnetic monopole solutions with finite energy and masses that can be as light as a few TeV. Specifically, we discuss, among other scenarios, modified Cho-Maison monopoles and magnetic monopoles in (string-inspired, higher derivative) Born-Infeld extensions of the hypercharge sector of the Standard Model. We also outline the conditions for which effective field theories describing the interaction of monopoles with photons are valid and can be used for result interpretation in monopole production at colliders. The experimental part of the review focuses on, past and present, cosmic and collider searches, including the latest bounds on monopole masses and magnetic charges by the ATLAS and MoEDAL experiments at the LHC, as well as prospects for future searches.

    hep-phhep-exhep-thInt.J.Mod.Phys.A(2020)·118 citations
16. 16*

    $\varphi$ meson mass and decay width in strange hadronic matter

    Rajesh Kumar🇮🇳 · Arvind Kumar🇮🇳

    The in-medium mass and decay width of the $\varphi$ meson in the hot asymmetric strange hadronic matter are calculated using an effective Lagrangian approach for $\varphi$ $K\bar{K}$ interaction. The in-medium contributions of $K\bar{K}$ loop to the $\varphi$ meson self-energy are computed by the medium modified kaon and antikaon mass which is evaluated using the chiral SU(3) model. To deal with the ultraviolet divergence, we regularize the loop integral of self-energy with a dipole form factor, and present the results for cut-off mass, ${\Lambda }_c$=3 GeV. In chiral model calculations, for strange matter, we find that the mass of kaons and antikaons decreases with the increase in baryonic density whereas the finite temperature causes an increase in the mass. We observed that the in-medium $\varphi$ meson mass decreases slowly with baryonic density whereas the decay width increases rapidly. The results in the present investigation support result in the literature which indicate a small downward shift in mass and a large broadening in the decay width. In the asymmetric strange hadronic matter, the study of the $\varphi$ mesons can be relevant for the compressed strange baryonic matter and experimental observables such as dilepton spectra which can result from the experiments in the future FAIR facility at GSI.

    hep-phnucl-thPRC(2020)·20 citations
17. 17*

    KOTO vs. NA62 Dark Scalar Searches

    Stefania Gori🇺🇸 · Gilad Perez🇮🇱 · Kohsaku Tobioka🇺🇸

    The two kaon factories, KOTO and NA62, are at the cutting edge of the intensity frontier, with an unprecedented numbers of long lived and charged Kaons, ~ 10^{13}, being measured and analyzed. These experiments have currently a unique opportunity to search for dark sectors. In this paper, we demonstrate that searches done at KOTO and NA62 are complementary, both probing uncharted territories. We consider two qualitatively different physics cases. In the first, we analyze models of axion-like-particles (ALP) which couple to gluons or electroweak gauge bosons. In the second, we introduce a model based on an approximate strange flavor symmetry that leads to a strong violation of the Grossman-Nir bound. For the first scenario, we design a new search strategy for the KOTO experiment, K_L -> pi^0 a -> 4 gamma . Its expected sensitivity on the branching ratio is at the level of 10^{-9}. This demonstrates the great potential of KOTO as a discovery machine. In addition, we revisit other bounds on ALPs from Kaon factories, highlighting the main sources of theoretical uncertainty, and collider experiments, and show new projections. For the second scenario, we show that the model may be compatible with the preliminary analysis of the KOTO-data that shows a hint for New Physics.

    hep-phhep-exJHEP(2020)·90 citations
18. 18*

    On the two-loop radiative origin of the smallest neutrino mass and the associated Majorana CP phase

    Zhi-zhong Xing🇨🇳 · Di Zhang🇨🇳

    Given a massless neutrino at a superhigh energy scale $\Lambda$ (e.g., in the minimal seesaw model with only two heavy Majorana neutrinos), we calculate quantum corrections to its initially vanishing mass $m_1^{}$ (or $m_3^{}$) and the associated Majorana CP phase $\rho$ (or $\varrho$) at the Fermi scale ${\Lambda }_{\mathrm{F}}^{}$ by means of the two-loop renormalization-group equations (RGEs) in the standard model and with the help of the latest neutrino oscillation data. The numerical results obtained from our analytical approximations are in good agreement with those achieved by numerically solving the two-loop RGEs. In particular, we confirm that a nonzero value of $m_1^{}$ (or $m_3^{}$) of $\mathcal{O}(10^{-13})$ eV at ${\Lambda }_{\mathrm{F}}^{}$ can be radiatively generated from $m_1^{}=0$ (or $m_3^{}=0$) at $\Lambda \simeq 10^{14}$ GeV in the SM, and find that $\rho$ (or $\varrho$) may accordingly acquire an appreciable physical value. As a nontrivial by-product, the evolution of all the other (initially nonzero) flavor parameters of massive neutrinos is studied both analytically and numerically, by just keeping their leading (i.e., one-loop) RGE-induced effects.

    hep-phhep-exPLB(2020)·15 citations
19. 19*

    Light Singlino Dark Matter at the LHC

    Monoranjan Guchait🇮🇳 · Arnab Roy🇮🇳

    The light singlino-like neutralino is expected to be a promising candidate for DM in the allowed parameter space of the NMSSM. The DM annihilation process takes place via the light Higgs bosons which are natural in this model. Identifying the allowed region of parameter space including various constraints, the detection prospect of such light DM candidate and Higgs bosons are explored at the LHC with its high luminosity options. Light Higgs bosons and the DM candidate, the lightest singlino-like neutralino are indirectly produced at the LHC via the SM Higgs production and its subsequent decays. Jet substructure techniques are used to tag boosted Higgs. It is found that the favourable range of masses of Higgs bosons and neutralino, compatible with a low mass DM solution, can be discovered with a reasonable signal significance ($\sim 5\sigma$) at the LHC, with the center of mass energy $\sqrt{s}=14$ TeV and integrated luminosity options $\mathcal{L}=300\mathrm{f}{\mathrm{b}}^{-1}$ and 3000 $\mathrm{f}{\mathrm{b}}^{-1}$.

    hep-phPRD(2020)·31 citations
20. 20*

    Z'-explorer: a simple tool to probe Z' models against LHC data

    Ezequiel Alvarez🇦🇷 · Mariel Estévez🇦🇷 · Rosa María Sandá Seoane (ICAS, Argentina)🇦🇷

    New Physics model building requires a vast number of cross-checks against available experimental results. In particular, new neutral, colorless, spin-1 bosons $Z^{\prime }$, can be found in many models. We introduce in this work a new easy-to-use software Z'-explorer which probes $Z^{\prime }$ models to all available decay channels at LHC. This program scrutinizes the parameter space of the model to determine which part is still allowed, which is to be shortly explored, and which channel is the most sensitive in each region of parameter space. User does not need to implement the model nor run any Monte Carlo simulation, but instead just needs to use the $Z^{\prime }$ mass and its couplings to Standard Model particles. We describe Z'-explorer backend and provide instructions to use it from its frontend, while applying it to a variety of $Z^{\prime }$ models. In particular we show Z'-explorer application and utility in a sequential Standard Model, a B-L $Z^{\prime }$ and a simplified two-sector or Warped/Composite model. The output of the program condenses the phenomenology of the model features, the experimental techniques and the search strategies in each channel in an enriching outcome. We find that compelling add-ons to the software would be to include correlation between decay channels, low-energy physics results, and Dark Matter searches. The software is open-source ready to use, and available for modifications, improvements and updates by the community.

    hep-phhep-exComput.Phys.Commun.(2021)·11 citations
21. 21*

    Higgs boson coupling as a probe of the sphaleron property

    Shinya Kanemura🇯🇵 · Masanori Tanaka🇯🇵

    Sphaleron is a non-perturbative solution of electroweak gauge theories, which is crucially important for the scenario of electroweak baryogenesis. The sphaleron energy depends on details of the mechanism for the electroweak symmetry breaking. We find that in many of new physics models the deviation of the sphaleron energy from the prediction in the standard model is proportional to that of the triple Higgs boson coupling with opposite signs. This interesting relation would be useful to determine the sphaleron energy by measuring this couplings at future collider experiments.

    hep-phPLB(2020)·20 citations
22. 22*

    The SVZ sum rules and the heavy quark limit for ${\Lambda }_Q$

    Zhen-Xing Zhao🇨🇳 · Run-Hui Li🇨🇳 · Yu-Ji Shi🇩🇪 · Si-Hong Zhou🇨🇳

    In this work, we evaluate the accuracy of the leading order results in Shifman-Vainshtein-Zakharov (SVZ) sum rules and the leading power results in the heavy quark limit for the mass of ${\Lambda }_Q$. Up to dim-5 condensate contributions are considered. By comparing with the experimental results, we find that the leading order results in SVZ sum rules can reach about 5\% accuracy both for ${\Lambda }_b$ and ${\Lambda }_c$, and it seems that better results can be obtained from the sum rules of the heavy quark limit both for ${\Lambda }_b$ and ${\Lambda }_c$. We re-check that the SVZ sum rules in the heavy quark limit coincide with the HQET sum rules. As a byproduct, we also have an exploratory discussion on the $ud$ diquark in ${\Lambda }_Q$.

    hep-ph3 citations
23. 23*

    Seeking massless dark photons in the decays of charmed hadrons

    Jhih-Ying Su🇹🇼 · Jusak Tandean🇹🇼

    A massless dark photon could affect standard-model particles only via higher-dimensional operators and would therefore have eluded recent searches for its massive counterpart, which were based on the assumption that the latter had renormalizable interactions with known fermions due to gauge kinetic mixing. In this study we entertain the possibility that the massless dark photon has nonnegligible flavor-changing dipole-type couplings with the $u$ and $c$ quarks, giving rise to the decays of charmed hadrons into a lighter hadron plus missing energy carried away by the dark photon. We propose to investigate decays of this kind, especially those in which the parents are the charmed pseudoscalar-mesons $D^{+}$, $D^0$, and $D_s^{+}$ and singly charmed baryons ${\Lambda }_c^{+}$, ${\Xi }_c^{+}$, and ${\Xi }_c^0$. Employing a simplified new-physics model satisfying the relevant constraints, we find that the branching fractions of these processes could be as large as several times $10^{-5}$. This suggests that one or more of them might in the near future fall within reach of the ongoing Belle II and BESIII experiments. Since the same underlying operators are responsible for all of these transitions, detecting one of them automatically implies particular predictions for the others, allowing for additional experimental checks on the massless-dark-photon scenario.

    hep-phhep-exPRD(2020)·23 citations
24. 24*

    Resonant Neutrino Self-Interactions

    Cyril Creque-Sarbinowski🇺🇸 · Jeffrey Hyde🇺🇸 · Marc Kamionkowski🇺🇸

    If neutrinos have self-interactions, these will induce scatterings between astrophysical and cosmic neutrinos. Prior work proposed to look for possible resulting resonance features in astrophysical neutrino spectra in order to seek a neutrino self-interaction which can be either diagonal in the neutrino flavor space or couple different neutrino flavors. The calculation of the astrophysical spectra involves either a Monte Carlo simulation or a computationally intensive numerical integration of an integro-partial-differential equation. As a result only limited regions of the neutrino self-interaction parameter space have been explored, and only flavor-diagonal self-interactions have been considered. Here, we present a fully analytic form for the astrophysical neutrino spectra for arbitrary neutrino number and arbitrary self-coupling matrix that accurately obtains the resonance features in the observable neutrino spectra. The results can be applied to calculations of the diffuse supernova neutrino background and of the spectrum from high-energy astrophysical neutrino sources. We illustrate with a few examples.

    hep-phastro-ph.COastro-ph.HEnucl-thPRD(2021)·41 citations
25. 25*

    Lectures: From quantum mechanics to the Standard Model

    Ben Gripaios🇬🇧

    The goal of these lectures is to introduce readers with a basic knowledge of undergraduate physics (specifically non-relativistic quantum mechanics, special relativity, and electromagnetism) to the `current theory of everything': the Standard Model of particle of physics. By the end of the course, readers should be able to make predictions for simple processes at the Large Hadron Collider, such as decay rates of the Higgs boson. Some discussion of the ongoing search for physics beyond the Standard Model is also included. Based on lectures given at the Universities of Cambridge (UK) and Canterbury (New Zealand).

    hep-phhep-th2 citations
26. 26*

    The Added Mass Effect and the Higgs Mechanism

    Govind S. Krishnaswami🇮🇳 · Sachin Phatak🇮🇳

    A rigid body accelerated through an inviscid, incompressible fluid appears to gain mass, which is encoded in an added mass tensor. Swimmers, air bubbles, submarines and airships are slowed down by the associated `added mass' force proportional to their acceleration, which is distinct from viscous drag and buoyancy. In particle physics, otherwise massless electrons, quarks, $W$ and $Z$ bosons, moving through the Higgs scalar field acquire masses encoded in a mass matrix. In this expository article we give an introduction to the fluid mechanical added mass effect through examples of potential flows in various dimensions and exploit a correspondence with the Higgs mechanism [introduced in Proc. R. Soc. A471: 20140803 (2015)] to relate this to how the $W$ and $Z$ bosons can get their masses, while leaving the photon massless. The correspondence relates the Higgs scalar field to the fluid, the vacuum expectation value of the Higgs field to a constant fluid density and quantum fluctuations around the Higgs condensate to compressional waves in the fluid. The shape of the rigid body encodes the pattern of gauge symmetry breaking through the eigenvalues of the corresponding mass matrices. Possible directions of acceleration of the rigid body are related to directions in the gauge Lie algebra with a `flat' direction in the body corresponding to a massless photon. Moreover, symmetries of the body are related to those of the scalar vacuum manifold. The Higgs boson may be viewed as the analog of a long wavelength fluid mode around an accelerated body.

    ↳ physics.flu-dynhep-phReson.(2020)·1 citation
27. 27*

    Impacts of dark energy on constraining neutrino mass after Planck 2018

    Ming Zhang🇨🇳 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳

    Considering the mass splittings of three active neutrinos, we investigate how the nature of dark energy affects the cosmological constraints on the total neutrino mass $\sum m_{\nu }$ using the latest cosmological observations. In this paper, some typical dark energy models, including $\Lambda$CDM, $w$CDM, CPL, and HDE models, are discussed. In the analysis, we also consider the effects from the neutrino mass hierarchies, i.e., the degenerate hierarchy (DH), the normal hierarchy (NH), and the inverted hierarchy (IH). We employ the current cosmological observations to do the analysis, including the Planck 2018 temperature and polarization power spectra, the baryon acoustic oscillations (BAO), the type Ia supernovae (SNe), and the Hubble constant $H_0$ measurement. In the $\Lambda$CDM+$\sum m_{\nu }$ model, we obtain the upper limits of the neutrino mass $\sum m_{\nu }<0.123$ eV (DH), $\sum m_{\nu }<0.156$ eV (NH), and $\sum m_{\nu }<0.185$ eV (IH) at the $95\%$ C.L., using the Planck+BAO+SNe data combination. For the $w$CDM+$\sum m_{\nu }$ model and the CPL+$\sum m_{\nu }$ model, larger upper limits of $\sum m_{\nu }$ are obtained compared to those of the $\Lambda$CDM+$\sum m_{\nu }$ model. The most stringent constraint on the neutrino mass, $\sum m_{\nu }<0.080$ eV (DH), is derived in the HDE+$\sum m_{\nu }$ model. In addition, we find that the inclusion of the local measurement of the Hubble constant in the data combination leads to tighter constraints on the total neutrino mass in all these dark energy models.

    ↳ astro-ph.COgr-qchep-phCommun.Theor.Phys.(2020)·31 citations
28. 28*

    Smooth flux-sheets with topological winding modes

    A. Bakry🇨🇳 · M. Deliyergiyev🇵🇱 · A. Galal🇪🇬 · M. Khalil Williams🇩🇪

    The inclusion of the Gaussian-curvature term in the bulk of Polyakov-Kleinert string action renders new boundary terms and conditions by Gauss-Bonnet theorem. Within a leading approximation, the eigenmodes of smooth worldsheets and the free-energy of a gas of open rigid strings appears to be altered at second order in the coupling by the topological term . In analogy to the topological $\theta$ term, the Gauss-Bonnet term is introduced into the effective action with a complex coupling to implement signed energy shifts. We investigate the rigid color flux-sheets between two static color sources near the critical point in the light of the topologically induced shifts. The Yang-Mills lattice data of the potential of static quark-antiquark $Q\bar{Q}$ in a heatbath is compared to the string potential. The Monte-Carlo data correspond to link-integrated Polyakov-loop correlators averaged over SU(3) gauge configurations at $\beta =6.0$. Substantial improvement in the fit behavior is displayed over the nonperturbative source separation distance $0.2$ fm to $1.0$ fm. Remarkably, the returned coupling parameter of the topological term from the fit exhibits a proportionality to a quantum number. These findings suggest that the manifested modes are the winding number of a topological particle on the string's worldsheet.

    ↳ hep-lathep-phhep-thnucl-th4 citations
29. 29*

    A pure general relativistic non-singular bouncing origin for the Universe

    Aurélien Barrau🇫🇷

    In this letter, we argue that the past of the Universe, extrapolated from standard physics and measured cosmological parameters, might be a non-singular bounce. We also show that, in this framework, quite stringent constraints can be put on the reheating temperature and number of inflationary e-folds, basically fixing $T_{RH}\sim T_{GUT}$ and $N\sim 70$. We draw some conclusions about the shape of the inflaton potential and raise the "naturalness" issue in this context. Finally, we argue that this could open a very specific window on the "pre big bounce" universe.

    ↳ gr-qcastro-ph.COhep-phEPJC(2020)·14 citations
30. 30*

    A Fourier-Cumulant Analysis for Multiharmonic Flow Fluctuation

    Seyed Farid Taghavi🇩🇪

    The Fourier analysis of the final particle distribution followed by cumulant study of the Fourier coefficient event-by-event fluctuation is one of the main approaches for testing the collective evolution in the heavy-ion collision. Using a multidimensional generating function, we propose a method to extract any possible cumulant of multiharmonic flow fluctuations and classify them in terms of the order of cumulants and harmonics involved in them. In particular, we show that there are 33 distinct cumulants with orders $2,3,4,5$ and harmonics $2,3,4,5$. We compute the normalized version of these cumulants from hydrodynamic simulation for Pb--Pb collisions based on {\tt T${}_{\text{R}}$ENTo}+{\tt VISH2+1}+{\tt UrQMD}. We compare the simulation with those normalized cumulants that the LHC has measured and predict the unmeasured ones. Comparing the initial and final state fluctuation normalized cumulants, we compute the linear and nonlinear hydrodynamic response couplings. We finally introduce the genuine three-particle correlation function containing information of all third-order cumulants.

    ↳ nucl-thhep-phnucl-exEPJC(2021)·15 citations
31. 31*

    On Restricted Weyl Symmetry

    Ichiro Oda🇯🇵

    We discuss the physics of a restricted Weyl symmetry in a curved space-time where a gauge parameter $\Omega (x)$ of Weyl transformation satisfies a constraint $\square \Omega =0$. First, we present a model of QED where we have a restricted gauge symmetry in the sense that a $U(1)$ gauge parameter $\theta (x)$ obeys a similar constraint $\square \theta =0$ in a flat Minkowski space-time. Next, it is precisely shown that a global scale symmetry must be spontaneously broken at the quantum level. Finally, we discuss the origin of the restricted Weyl symmetry and show that its symmetry can be derived from a full Weyl symmetry by taking a gauge condition $R=0$ in the BRST formalism.

    ↳ hep-thgr-qchep-phPRD(2020)·15 citations
32. 32*

    $F_K/F_{\pi }$ from Möbius domain-wall fermions solved on gradient-flowed HISQ ensembles

    Nolan Miller🇺🇸 · Henry Monge-Camacho🇺🇸 · Chia Cheng Chang🇯🇵 · Ben Hörz🇺🇸 · Enrico Rinaldi🇯🇵 · Dean Howarth🇺🇸 · Evan Berkowitz🇺🇸 · David A. Brantley🇺🇸 · Arjun Singh Gambhir🇺🇸 · Christopher Körber🇺🇸 · Christopher J. Monahan🇺🇸 · M. A. Clark🇺🇸 and 6 other authors

    We report the results of a lattice quantum chromodynamics calculation of $F_K/F_{\pi }$ using Möbius domain-wall fermions computed on gradient-flowed $N_f=2+1+1$ highly-improved staggered quark (HISQ) ensembles. The calculation is performed with five values of the pion mass ranging from $130\lesssim m_{\pi }\lesssim 400$ MeV, four lattice spacings of $a\sim 0.15,0.12,0.09$ and $0.06$ fm and multiple values of the lattice volume. The interpolation/extrapolation to the physical pion and kaon mass point, the continuum, and infinite volume limits are performed with a variety of different extrapolation functions utilizing both the relevant mixed-action effective field theory expressions as well as discretization-enhanced continuum chiral perturbation theory formulas. We find that the $a\sim 0.06$ fm ensemble is helpful, but not necessary to achieve a subpercent determination of $F_K/F_{\pi }$. We also include an estimate of the strong isospin breaking corrections and arrive at a final result of $F_{K^{\pm }}/F_{{\pi }^{\pm }}=1.1942(45)$ with all sources of statistical and systematic uncertainty included. This is consistent with the Flavour Lattice Averaging Group average value, providing an important benchmark for our lattice action. Combining our result with experimental measurements of the pion and kaon leptonic decays leads to a determination of $|V_{us}|/|V_{ud}|=0.2311(10)$.

    ↳ hep-lathep-exhep-phnucl-thPRD(2020)·57 citations
33. 33*

    Bruno Touschek in Glasgow. The making of a theoretical physicist

    Giulia Pancheri🇮🇹 · Luisa Bonolis🇩🇪

    In the history of the discovery tools of last century particle physics, central stage is taken by elementary particle accelerators and in particular by colliders. In their start and early development, a major role was played by the Austrian born Bruno Touschek, who proposed and built the first electron positron collider, AdA, in Italy, in 1960. In this note, we present a period of Touschek's life barely explored in the literature, namely the five years he spent at University of Glasgow, first to obtain his doctorate in 1949 and then as a lecturer. We shall highlight his formation as a theoretical physicist, his contacts and correspondence with Werner Heisenberg in Göttingen and Max Born in Edinburgh, as well as his close involvement with colleagues intent on building modern particle accelerators in Glasgow, Malvern, Manchester and Birmingham. We shall discuss how the Fuchs affair, which unraveled in early 1950, may have influenced his decision to leave the UK, and how contacts with the Italian physicist Bruno Ferretti led Touschek to join the Guglielmo Marconi Physics Institute of University of Rome in January 1953.

    ↳ physics.hist-phhep-phphysics.acc-ph4 citations
34. 34*

    Spurious gauge-invariance of higher-order contributions to the spectral energy density of the relic gravitons

    Massimo Giovannini🇨🇭

    In the same way as the energy density associated with the tensor modes of the geometry modifies the evolution of the curvature perturbations, the scalar modes may also indirectly affect the cosmic backgrounds of relic gravitons by inducing higher-order corrections that are only superficially gauge-invariant. This spurious gauge-invariance gets manifest when the effective anisotropic stresses, computed in different coordinate systems, are preliminarily expressed in a form that only depends on the curvature inhomogeneities defined on comoving orthogonal hypersurfaces and on their corresponding time derivatives. Using this observation we demonstrate in general terms that the higher-order contributions derived in diverse coordinate systems coincide when the wavelengths are smaller than the sound horizon defining the evolution of the curvature inhomogeneities but they lead to sharply different results in the opposite limit. A similar drawback arises when the energy density of the relic gravitons is derived from competing energy-momentum pseudo-tensors and should be consistently taken into account in the related phenomenological discussions.

    ↳ hep-thastro-ph.COgr-qchep-phInt.J.Mod.Phys.A(2020)·22 citations
35. 35*

    Exploring the $\Lambda$-deuteron interaction via correlations in heavy-ion collisions

    J. Haidenbauer🇩🇪

    $\Lambda$-deuteron two-particle momentum correlation functions, to be measured in high-energy heavy-ion collisions, are investigated. In particular, the question is addressed whether such correlations can serve as an additional and alternative source of information on the elementary $\Lambda N$ interaction. The study is performed within the Lednicky-Lyuboshits formalism, utilizing an effective range expansion for the two relevant $S$-wave $\Lambda d$ amplitudes with parameters taken from the literature. It is found that in collisions characterized by a large emitting source the $\Lambda d$ correlation function is predominatly sensitive to the quartet state (${}^4{S}_{3/2}$). In contrast, for small source sizes the contribution from the doublet partial wave (${}^2{S}_{1/2}$) could be significant. Though the latter is constrained by the hypertriton binding energy, its present experimental uncertainty impedes an accurate determination of the doublet amplitude and, in turn, complicates conclusions on the quartet state.

    ↳ nucl-thhep-phPRC(2020)·32 citations
36. 36*

    Magnetic monopoles and fermion number violation in chiral matter

    Naoki Yamamoto🇯🇵

    We show that the presence of a magnetic monopole in position space gives rise to a violation of the fermion number conservation in chiral matter. Using the chiral kinetic theory, we derive a model-independent expression of such a violation in nonequilibrium many-body systems of chiral fermions. In local thermal equilibrium at finite temperature and chemical potential, in particular, this violation is proportional to the chemical potential with a topologically quantized coefficient. These consequences are due to the interplay between the Dirac monopole in position space and the Berry monopole in momentum space. Our mechanism can be applied to study the roles of magnetic monopoles in the nonequilibrium evolution of the early Universe.

    ↳ hep-thastro-ph.COcond-mat.mes-hallhep-ph10 citations
37. 37*

    Inflation and Decoupling

    Gia Dvali🇩🇪 · Alex Kehagias🇬🇷 · Antonio Riotto🇨🇭

    Decoupling of heavy modes in effective low energy theory is one of the most fundamental concepts in physics. It tells us that modes must have a negligible effect on the physics of gravitational backgrounds with curvature radius larger than their wavelengths. Despite this, there exist claims that trans-Planckian modes put severe bound on the duration of inflation even when the Hubble parameter is negligible as compared to the Planck mass. If true, this would mean that inflation violates the principle of decoupling or at least requires its reformulation. We clarify the fundamental misconception on which these bounds are based and respectively refute them. Our conclusion is that inflation fully falls within the validity of a reliable effective field theory treatment and does not suffer from any spurious trans-Planckian problem.

    ↳ hep-thastro-ph.COgr-qchep-ph28 citations
38. 38*

    BCJ, worldsheet quantum algebra and KZ equations

    Chih-Hao Fu🇨🇳 · Yihong Wang🇹🇼

    We exploit the correspondence between twisted homology and quantum group to construct an algebra explanation of the open string kinematic numerator. In this setting the representation depends on string modes, and therefore the cohomology content of the numerator, as well as the location of the punctures. We show that quantum group root system thus identified helps determine the Casimir appears in the Knizhnik-Zamolodchikov connection, which can be used to relate representations associated with different puncture locations.

    ↳ hep-thhep-phmath.QAJHEP(2020)·6 citations
39. 39*

    Physics potential of timing layers in future collider detectors

    S.V. Chekanov🇺🇸 · A.V. Kotwal🇺🇸 · C.-H. Yeh🇹🇼 · S.-S. Yu🇹🇼

    The physics potential of timing layers with a few tens of pico-second resolution in the calorimeters of future collider detectors is explored. These studies show how such layers can be used for particle identification and illustrate the potential for detecting new event signatures originating from physics beyond the standard model.

    ↳ physics.ins-dethep-phJINST(2020)·10 citations
40. 40*

    Detecting circular polarisation in the stochastic gravitational-wave background from a first-order cosmological phase transition

    John Ellis🇬🇧 · Malcolm Fairbairn🇬🇧 · Marek Lewicki🇬🇧 · Ville Vaskonen🇬🇧 · Alastair Wickens🇬🇧

    We discuss the observability of circular polarisation of the stochastic gravitational-wave background (SGWB) generated by helical turbulence following a first-order cosmological phase transition, using a model that incorporates the effects of both direct and inverse energy cascades. We explore the strength of the gravitational-wave signal and the dependence of its polarisation on the helicity fraction, ${\zeta }_{\ast }$, the strength of the transition, $\alpha$, the bubble size, $R_{\ast }$, and the temperature, $T_{\ast }$, at which the transition finishes. We calculate the prospective signal-to-noise ratios of the SGWB strength and polarisation signals in the LISA experiment, exploring the parameter space in a way that is minimally sensitive to the underlying particle physics model. We find that discovery of SGWB polarisation is generally more challenging than measuring the total SGWB signal, but would be possible for appropriately strong transitions with large bubble sizes and a substantial polarisation fraction.

    ↳ astro-ph.COgr-qchep-phJCAP(2020)·22 citations
41. 41*

    Radio frequency emissions from dark-matter-candidate magnetized quark nuggets interacting with matter

    J. Pace VanDevender🇺🇸 · C. Jerald Buchenauer🇺🇸 · Chunpei Cai🇺🇸 · Aaron P. VanDevender🇺🇸 · Benjamin A. Ulmen🇺🇸

    Quark nuggets are theoretical objects composed of approximately equal numbers of up, down, and strange quarks. They are also called strangelets, nuclearites, AQNs, slets, Macros, and MQNs. Quark nuggets are a candidate for dark matter, which has been a mystery for decades despite constituting $\sim 85\%$ of matter. Most previous models of quark nuggets have assumed no intrinsic magnetic field; however, Tatsumi found that quark nuggets may exist in magnetars as a ferromagnetic liquid with a magnetic field between $10^{11}$ T and $10^{13}$ T. We apply that result to quark nuggets, a dark-matter candidate consistent with the Standard Model, and report results of analytic calculations and simulations that show they spin up and emit electromagnetic radiation at $\sim 10^4$ Hz to $\sim 10^9$ Hz after passage through planetary environments. The results depend strongly on the value of $B_o$, which is a parameter to guide and interpret observations. A proposed sensor system with three satellites at 51,000 km altitude illustrates the feasibility of using radio-frequency emissions to detect 0.003 to 1600 MQNs, depending on Bo, during a five year mission.

    ↳ astro-ph.HEastro-ph.GAgr-qchep-phSci.Rep.(2020)·5 citations
42. 42*

    Getting High: High Fidelity Simulation of High Granularity Calorimeters with High Speed

    Erik Buhmann🇩🇪 · Sascha Diefenbacher🇩🇪 · Engin Eren🇩🇪 · Frank Gaede🇩🇪 · Gregor Kasieczka🇩🇪 · Anatolii Korol🇺🇦 · Katja Krüger🇩🇪

    Accurate simulation of physical processes is crucial for the success of modern particle physics. However, simulating the development and interaction of particle showers with calorimeter detectors is a time consuming process and drives the computing needs of large experiments at the LHC and future colliders. Recently, generative machine learning models based on deep neural networks have shown promise in speeding up this task by several orders of magnitude. We investigate the use of a new architecture -- the Bounded Information Bottleneck Autoencoder -- for modelling electromagnetic showers in the central region of the Silicon-Tungsten calorimeter of the proposed International Large Detector. Combined with a novel second post-processing network, this approach achieves an accurate simulation of differential distributions including for the first time the shape of the minimum-ionizing-particle peak compared to a full GEANT4 simulation for a high-granularity calorimeter with 27k simulated channels. The results are validated by comparing to established architectures. Our results further strengthen the case of using generative networks for fast simulation and demonstrate that physically relevant differential distributions can be described with high accuracy.

    ↳ physics.ins-dethep-exhep-phphysics.data-anComput.Softw.Big Sci.(2021)·138 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.