Fri·Aug 5, 2022Friday·August 5, 2022

1. 01*

   Multi-jet Merging with TMD Parton Branching

   A. Bermudez Martinez🇩🇪 · F. Hautmann🇨🇭 · M.L. Mangano🇨🇭

   One of the main theoretical systematics in studies of final states with large jet multiplicities at high-energy hadron colliders is associated with the merging of QCD parton showers and hard-scattering matrix elements. We present a method to incorporate the physics of transverse momentum recoils due to initial-state shower evolution into multi-jet merging algorithms by using the concept of transverse momentum dependent (TMD) distributions and the associated parton branching. We investigate the dependence on the merging scale and illustrate the impact of the new method at the level of both exclusive and inclusive final-state observables by studying differential jet rates, transverse momentum spectra and multiplicity distributions, using vector boson + jets events at the LHC as a case study.

   hep-phJHEP(2022)·26 citations
2. 02*

   Possibility of experimental study on nonleptonic $B_c^{\ast }$ weak decays

   Yueling Yang🇨🇳 · Liting Wang🇨🇳 · Jinshu Huang🇨🇳 · Qin Chang🇨🇳 · Junfeng Sun🇨🇳

   The ground vector $B_c^{\ast }$ meson has not yet been experimentally discovered until now. Besides the dominant electromagnetic decays, nonleptonic weak decays provide another choice to search for the mysterious $B_c^{\ast }$ mesons. Inspired by the potential prospects of $B_c^{\ast }$ mesons in future high-luminosity colliders, nonleptonic $B_c^{\ast }$ weak decays induced by bottom and charm quark decays are studied within the SM by using a naive factorization approach. It is found that for $B_c^{\ast }$ $\to$ $B_{s,d}\pi$, $B_{s,d}^{\ast }\pi$, $B_{s,d}\rho$, $B_{s}K$, $B_s^{\ast }K$, $B_s{K}^{\ast }$, ${\eta }_c(1S,2S)\pi$, ${\eta }_c(1S,2S)\rho$ and $\psi (1S,2S)\pi$ decays, a few hundred and even thousand of events might be observable in CEPC, FCC-ee and LHCb@HL-LHC experiments.

   hep-phhep-exCPC(2023)·2 citations
3. 03*

   Analysis of 2S singly heavy baryons in HQET

   K. K. Vishwakarma🇮🇳 · A. Upadhyay🇮🇳

   We have employed HQET to determine the masses of radially excited ($n=2$) S-wave charm and bottom baryons. The HQET Lagrangian containing the non-perturbative parameters is shown with heavy baryon fields. The non-perturbative parameters, couplings, and decay widths are also studied for the S-wave singly heavy baryons. The HQET parameters $\overline{\Lambda }$, ${\lambda }_1$ and ${\lambda }_2$ are calculated for the ground state ($n=1$) using the masses of S-wave baryons. The mass term ratios of $n=1$ and $n=2$ mesons and baryons containing parameters $\overline{\Lambda }$ and ${\lambda }_1$ are studied by varying the bottom quark mass. This analysis shows that heavy quark behaves the same inside mesons and baryons in both 1S and 2S states. The HQET symmetry of $\overline{\Lambda }$ is used to find the parameters and masses for $n=2$ S-wave baryons. The variation of mass of 2S baryons with the non-perturbative parameters ${\lambda }_1$ and ${\lambda }_2$ is discussed. The Regge trajectories are also plotted in the $(n,M^2)$ plane using masses of $n=1$ and 2 charm and bottom baryons. The Regge trajectories are parallel and equidistant lines in the $(n,M^2)$ plane. We have also studied the strong decays of charm and bottom baryons for both $n=1$ and $n=2$ states. We have estimated the coupling constants $g_1=0.913_{-0.017}^{+0.010}$ and $g_2=0.559_{-0.010}^{+0.006}$ for $n=1$, and $\frac{{\tilde{g}}_1}{{\tilde{g}}_2}=1.52$ for $n=2$. We have also shown the semi-electronic decays rates of charm baryons in the spectator heavy quark approximation for $1S\to 1S$, $2S\to 1S$ and $2S\to 2S$ transitions. The decay rates for $1S\to 1S$ transitions are of same order as $2S\to 1S$ transitions. This analysis gives a good agreement with available theoretical and experimental data.

   hep-phInt.J.Mod.Phys.A(2024)·6 citations
4. 04*

   Cornell potential in generalized Soft Wall holographic model

   Sergey Afonin🇷🇺 · Timofey Solomko🇷🇺

   We derive and analyze the confinement potential of the Cornell type within the framework of the generalized Soft Wall holographic model that includes a parameter controlling the intercept of the linear Regge spectrum. In the phenomenology of Regge trajectories, this parameter is very important for the quantitative description of experimental data. Our analysis shows that the ''linear plus Coulomb'' confinement potential obtained in the scalar channel is quantitatively consistent with the phenomenology and lattice simulations while the agreement in the vector channel is qualitative only. This result indicates the key role of the vacuum scalar sector in the formation of the confinement potential. As a by-product the overall consistency of our holographic description of confinement potential seems to confirm the glueball nature of the scalar meson $f_0(1500)$.

   hep-phhep-thnucl-thJ.Phys.G(2022)·10 citations
5. 05*

   Virtual neutrino propagation at short baselines

   Vadim A. Naumov🇷🇺 · Dmitry S. Shkirmanov🇷🇺

   Within a covariant perturbative field-theoretical approach, the wave-packet modified neutrino propagator is expressed as an asymptotic expansion in powers of dimensionless Lorentz- and rotation-invariant variables. The expansion is valid at high energies and short but macroscopic space-time distances between the vertices of the proper Feynman macrodiagram. In terms of duality between the propagator and the effective neutrino wave packet, at short times and distances, neutrinos are deeply virtual and move quasiclassically. In the lowest-order approximation, this leads to the classical inverse-square dependence of the modulus squared flavor transition amplitude and related neutrino-induced event rate from distance $L$ between the source and detector, and the above-mentioned asymptotics results in the corrections to the classical behavior represented by powers of $L^2$. This is very different from the long-baseline regime, where similar corrections are given by an asymptotic expansion in inverse powers of $L^2$. However, in both short- and long-baseline regimes, the main corrections lead to a decrease in number of neutrino events.

   hep-phhep-thquant-phEPJC(2022)·7 citations
6. 06*

   Semi-inclusive electroproduction of hidden-charm and double-charm hadronic molecules

   Pan-Pan Shi🇨🇳 · Feng-Kun Guo🇨🇳 · Zhi Yang🇨🇳

   The semi-inclusive electroproduction of exotic hadrons, including the $T_{cc}$, $P_{cs}$, and hidden-charm baryon-antibaryon states, is explored under the assumption that they are $S$-wave hadronic molecules of a pair of charmed hadrons. We employ the Monte Carlo event generator Pythia to produce the hadron pairs and then bind them together to form hadronic molecules. With the use of such a production mechanism, the semi-inclusive electroproduction rates are estimated at the order-of-magnitude level. Our results indicate that a larger number of $P_{cs}$ states and ${\Lambda }_c{\bar{\Lambda }}_c$ molecules can be produced at the proposed electron-ion colliders in China (EicC) and in the US (EIC). The results also suggest that the $T_{cc}$ states and other hidden-charm baryon-antibaryon states can be searched for at EIC. Besides, the potential 24-GeV upgrade of the Continuous Beam Accelerator Facility at the Thomas Jefferson National Accelerator Facility can play an important role in the search for the hidden-charm tetraquark and pentaquark states due to its high luminosity.

   hep-phhep-exnucl-exnucl-thPRD(2022)·14 citations
7. 07*

   Disintegration of beauty: a precision study

   Alexander Lenz🇩🇪 · Maria Laura Piscopo🇩🇪 · Aleksey V. Rusov🇩🇪

   We update the Standard Model (SM) predictions for $B$-meson lifetimes within the heavy quark expansion (HQE). Including for the first time the contribution of the Darwin operator, SU(3)${}_F$ breaking corrections to the matrix element of dimension-six four-quark operators and the so-called eye-contractions, we obtain for the total widths $\Gamma (B^{+})=(0.58_{-0.07}^{+0.11})\text{mbox}{ps}^{-1}$, $\Gamma (B_d)=(0.63_{-0.07}^{+0.11})\text{mbox}{ps}^{-1}$, $\Gamma (B_s)=(0.63_{-0.07}^{+0.11})\text{mbox}{ps}^{-1}$, and for the lifetime ratios $\tau (B^{+})/\tau (B_d)=1.086\pm 0.022$, $\tau (B_s)/\tau (B_d)=1.003\pm 0.006(1.028\pm 0.011)$. The two values for the last observable arise from using two different sets of input for the non-perturbative parameters ${\mu }_{\pi }^2(B_d)$, ${\mu }_G^2(B_d)$, and ${\rho }_D^3(B_d)$ as well as from different estimates of the SU(3)${}_F$ breaking in these parameters. Our results are overall in very good agreement with the corresponding experimental data, however, there seems to emerge a tension in $\tau (B_s)/\tau (B_d)$ when considering the second set of input parameters. Specifically, this observable is extremely sensitive to the size of the parameter ${\rho }_D^3(B_d)$ and of the SU(3)${}_F$ breaking effects in ${\mu }_{\pi }^2$, ${\mu }_G^2$ and ${\rho }_D^3$; hence, it is of utmost importance to be able to better constrain all these parameters. In this respect, an extraction of ${\mu }_{\pi }^2(B_s),{\mu }_G^2(B_s),{\rho }_D^3(B_s)$ from future experimental data on inclusive semileptonic $B_s$-meson decays or from direct non-perturbative calculations, as well as more insights about the value of ${\rho }_D^3(B)$ extracted from fit, would be very helpful in reducing the corresponding theory uncertainties.

   hep-phhep-exJHEP(2023)·46 citations
8. 08*

   Antenna subtraction at NNLO with identified hadrons

   Thomas Gehrmann🇨🇭 · Giovanni Stagnitto🇨🇭

   We extend the antenna subtraction method to include hadron fragmentation processes up to next-to-next-to-leading order (NNLO) in QCD in $e^{+}{e}^{-}$ collisions. To handle collinear singularities associated with the fragmentation process, we introduce fragmentation antenna functions in final-final kinematics with associated phase space mappings. These antenna functions are integrated over the relevant phase spaces, retaining their dependence on the momentum fraction of the fragmenting parton. The integrated antenna functions are cross-checked against the known NNLO coefficient functions for identified hadron production from ${\gamma }^{\ast }/Z^{\ast }\to q\bar{q}$ and $H\to gg$ processes.

   hep-phJHEP(2022)·16 citations
9. 09*

   NNLO Photon Production with Realistic Photon Isolation

   X. Chen🇩🇪 · T. Gehrmann🇨🇭 · E.W.N. Glover🇬🇧 · M. Höfer🇩🇪 · A. Huss🇨🇭 · R. Schürmann

   Isolated photon production at hadron colliders proceeds via direct production and fragmentation processes. Theory predictions for the isolated photon and photon-plus-jet cross section often impose idealised photon isolation criteria, eliminating the fragmentation contribution and introducing a systematic uncertainty in the comparison to data. We present NNLO predictions for the photon-plus-jet cross section with the experimental isolation including both, direct and fragmentation contributions. Predictions with two different parton-to-photon fragmentation functions are compared, allowing for an estimation of the uncertainty stemming from the only loosely constrained photon fragmentation functions.

   hep-phPoS(2022)·13 citations
10. 10*

    Axion-like particles from primordial black hole evaporation and their detection in neutrino experiments

    Tong Li🇨🇳 · Rui-Jia Zhang🇨🇳

    The primordial black holes (PBHs) play as a novel source to radiate light elementary particles of energies in the region of a few hundred MeV. We explore the possibility that the axion-like particles (ALPs) with mass less than 1 MeV are produced from PBH evaporation. The absorption of light ALPs in the underground detector targets then induces energetic photoelectron signatures in current and future neutrino experiments. Utilizing the PBH ALP event rate, we place general exclusion limits on the axion couplings at Super-K and Hyper-K. We also translate these limits into the upper bound on the fraction of DM composed of PBHs $f_{\mathrm{PBH}}$.

    hep-phPRD(2022)·15 citations
11. 11*

    Dark Matter and Neutrino Masses in a Portalino-like Model

    Dugald Hepburn🇬🇧 · Stephen M. West🇬🇧

    We explore a Portalino-like model of dark matter and neutrino masses in which right-handed neutrino fields connect gauge neutral operators from the Standard Model and Hidden Sector. Neutrino masses are generated via a seesaw-like mechanism that can explain the light active neutrino masses. The model includes a ``Portalino'' state that connects the two sectors via the neutrino portal. Dark Matter in this model consists of a hidden sector Dirac fermion that dominantly freezes-out via resonant annihilations into other hidden sector states, which ultimately results in a population of Portalinos. Due to small mixing in the extended neutrino sector these Portalinos tend to be cosmologically long lived, decaying into Standard Model particles leading to constraints on the model from Big Bang Nucleosynthesis and measurements of the Cosmic Microwave Background radiation. Combining these limits with direct constraints on the size of the Portalino-neutrino mixing and the assumptions of the model the viable mass ranges for the Portalino states are found to be 0.02 eV $\lesssim m_n\lesssim$ 6.4 eV or 489 MeV $\lesssim m_n\lesssim$ TeV. Indirect dark matter signals in the form of highly boosted, mono-energetic Portalinos produced in Dark Matter annihilations provide a target for neutrino telescopes.

    hep-phEPJC(2023)·5 citations
12. 12*

    Doubly Heavy Tetraquarks in the Born-Oppenheimer approximation

    Luciano Maiani🇮🇹 · Alessandro Pilloni🇮🇹 · Antonio D. Polosa🇮🇹 · Veronica Riquer🇮🇹

    Tetraquarks QQq*q* are found to be described remarkably well with the Quantum Chromodynamics version of the Hydrogen bond, as treated with the Born-Oppenheimer approximation. We show the robustness of the method by computing the mass of the observed Tcc tetraquark following two different paths. Relying on this, we provide a prediction for the mass of the expected Tbb particle. The average sizes of tetraquarks are estimated to be approximately 3 - 5 GeV**-1. As a consequence hyperfine separations are not expected to be sizeable. We discussed possible reasons why LHCb has observed only one state in the DD* spectrum.

    hep-phPLB(2023)·32 citations
13. 13*

    ${\gamma }_5$ in dimensional regularization -- a no-compromise approach using the BMHV scheme

    Hermès Bélusca-Maïto🇭🇷 · Amon Ilakovac🇭🇷 · Marija Ma{\dj}or-Božinović🇭🇷 · Paul Kühler🇩🇪 · Dominik Stöckinger🇩🇪

    ${\gamma }_5$ is notoriously difficult to define in $D$ dimensions. The traditional BMHV scheme employs a non-anticommuting ${\gamma }_5$. Its key advantage is mathematical consistency and the existence of all-order proofs. Its disadvantage is the spurious breaking of gauge invariance in chiral gauge theories like the electroweak standard model. Our research programme aims to determine the special finite counterterms which are necessary to restore gauge invariance, to allow more straightforward applications of the BMHV scheme and to cross-check alternative schemes. In these proceedings we present the key concepts and methods, and we outline the calculational procedure and present results for an abelian gauge theory at the 2-loop level. An important observation is the simplicity of the results -- three types of symmetry-restoring counterterms are sufficient at the 2-loop level.

    hep-phPoS(2022)·7 citations
14. 14*

    Continuum-extrapolated NNLO Valence PDF of Pion at the Physical Point

    Xiang Gao🇺🇸 · Andrew D. Hanlon🇺🇸 · Nikhil Karthik🇺🇸 · Swagato Mukherjee🇺🇸 · Peter Petreczky🇺🇸 · Philipp Scior🇺🇸 · Shuzhe Shi🇺🇸 · Sergey Syritsyn🇺🇸 · Yong Zhao🇺🇸 · Kai Zhou🇩🇪

    We present lattice QCD calculations of valence parton distribution function (PDF) of pion employing next-to-next-leading-order (NNLO) perturbative QCD matching. Our calculations are based on three gauge ensembles of 2+1 flavor highly improved staggered quarks and Wilson--Clover valance quarks, corresponding to pion mass $m_{\pi }=140$~MeV at a lattice spacing $a=0.076$~fm and $m_{\pi }=300$~MeV at $a=0.04,0.06$~fm. This enables us to present, for the first time, continuum-extrapolated lattice QCD results for NNLO valence PDF of the pion at the physical point. Applying leading-twist expansion for renormalization group invariant (RGI) ratios of bi-local pion matrix elements with NNLO Wilson coefficients we extract $2^{\mathrm{nd}}$, $4^{\mathrm{th}}$ and $6^{\mathrm{th}}$ Mellin moments of the PDF. We reconstruct the Bjorken-$x$ dependence of the NNLO PDF from real-space RGI ratios using a deep neural network (DNN) as well as from momentum-space matrix elements renormalized using a hybrid-scheme. All our results are in broad agreement with the results of global fits to the experimental data carried out by the xFitter and JAM collaborations.

    ↳ hep-lathep-exhep-phnucl-ex+1PRD(2022)·77 citations
15. 15*

    Cosmological implications of photon-flux upper limits at ultra-high energies in scenarios of Planckian-interacting massive particles for dark matter

    The Pierre Auger Collaboration: P. Abreu🇵🇹 · M. Aglietta🇮🇹 · J.M. Albury🇦🇺 · I. Allekotte🇦🇷 · K. Almeida Cheminant🇵🇱 · A. Almela🇦🇷 · J. Alvarez-Muñiz🇪🇸 · R. Alves Batista🇳🇱 · J. Ammerman Yebra🇪🇸 · G.A. Anastasi🇮🇹 · L. Anchordoqui🇺🇸 · B. Andrada🇦🇷 and 364 other authors

    Using the data of the Pierre Auger Observatory, we report on a search for signatures that would be suggestive of super-heavy particles decaying in the Galactic halo. From the lack of signal, we present upper limits for different energy thresholds above $\gtrsim 10^8$\,GeV on the secondary by-product fluxes expected from the decay of the particles. Assuming that the energy density of these super-heavy particles matches that of dark matter observed today, we translate the upper bounds on the particle fluxes into tight constraints on the couplings governing the decay process as a function of the particle mass. Instantons, which are non-perturbative solutions to Yang-Mills equations, can give rise to decay channels otherwise forbidden and transform stable particles into meta-stable ones. Assuming such instanton-induced decay processes, we derive a bound on the reduced coupling constant of gauge interactions in the dark sector: ${\alpha }_X\lesssim 0.09$, for $10^9\lesssim M_X/\text{GeV}<10^{19}$. Conversely, we obtain that, for instance, a reduced coupling constant ${\alpha }_X=0.09$ excludes masses $M_X\gtrsim 3\times 10^{13}$GeV. In the context of dark matter production from gravitational interactions alone during the reheating epoch, we derive constraints on the parameter space that involves, in addition to $M_X$ and ${\alpha }_X$, the Hubble rate at the end of inflation, the reheating efficiency, and the non-minimal coupling of the Higgs with curvature.

    ↳ astro-ph.HEastro-ph.COhep-phPRD(2023)·41 citations
16. 16*

    The $S$ matrices of elastic $\alpha$-${}^{12}$C scattering at low energies in effective field theory

    Shung-Ichi Ando (Sunmoon U.)🇰🇷

    The elastic $\alpha$-${}^{12}$C scattering at low energies for $l=0,1,2,3,4,5,6$ is studied in effective field theory. We discuss the construction of the $S$ matrices of elastic $\alpha$-${}^{12}$C scattering in terms of the amplitudes of sub-threshold bound and resonant states of ${}^{16}$O, which are calculated from the effective Lagrangian. The parameters appearing in the $S$ matrices are fitted to the phase shift data below the $p$-${}^{15}$N breakup threshold energy, and we find that the phase shifts are well described within the theory.

    ↳ nucl-thhep-phnucl-exPRC(2023)·12 citations
17. 17*

    Noise Effects on Pade Approximants and Conformal Maps

    Ovidiu Costin · Gerald V. Dunne🇺🇸 · Max Meynig🇺🇸

    We analyze the properties of Pade and conformal map approximants for functions with branch points, in the situation where the expansion coefficients are only known with finite precision or are subject to noise. We prove that there is a universal scaling relation between the strength of the noise and the expansion order at which Pade or the conformal map breaks down. We illustrate this behavior with some physically relevant model test functions and with two non-trivial physical examples where the relevant Riemann surface has complicated structure

    ↳ math-phcond-mat.stat-mechhep-phhep-th+1J.Phys.A(2022)·9 citations
18. 18*

    Charge gap in SU(3) Yang-Mills-plus-nonlinear-spinor-field theory

    Vladimir Dzhunushaliev🇰🇿 · Vladimir Folomeev🇰🇬 · Daulet Berkimbayev🇰🇿

    Particlelike solutions in SU(3) gauge Yang-Mills theory with color magnetic and electric fields sourced by a nonlinear spinor field are obtained. The asymptotic behavior of these fields is studied. It is shown that the electric field exhibits the Coulomb asymptotic behavior, and one of the color components of the magnetic field behaves asymptotically as the field of a magnetic dipole. This allows one to determine the corresponding charge and magnetic moment. It is shown that profiles of the color charge and magnetic moment have global minima, which may be called charge and magnetic moment gaps. The relationship between the total energy of the system and the color charge is obtained. The physical reason for the appearance of the mass, charge, and magnetic moment gaps in the theory under consideration is discussed.

    ↳ hep-thhep-phEPJC(2023)·2 citations
19. 19*

    Proton number cumulants and correlation functions from hydrodynamics and the QCD phase diagram

    Volodymyr Vovchenko🇺🇸 · Volker Koch🇺🇸 · Chun Shen🇺🇸

    We analyze the behavior of (net-)proton number cumulants in central collisions of heavy ions across a broad collision energy range by utilizing hydrodynamic simulations. The calculations incorporate essential non-critical contributions to proton fluctuations such as repulsive baryonic core and exact baryon number conservation. The experimental data are consistent with non-critical physics at collision energies $\sqrt{s_{\mathrm{NN}}}\ge 20$ GeV. The data from STAR and HADES Collaborations at lower collision energies indicate an excess of (multi-)proton correlations over the non-critical reference. This observation is discussed in the context of different mechanisms, including the possibility of a critical point in the baryon-rich region of the QCD phase diagram.

    ↳ nucl-thhep-phActa Phys.Polon.Supp.(2023)·1 citation
20. 20*

    On the positivity of Coon amplitude in D=4

    Joydeep Chakravarty🇮🇳 · Pronobesh Maity🇮🇳 · Amiya Mishra🇮🇳

    The Coon amplitude is the unique solution to duality constraints with logarithmic Regge trajectories. A striking feature of this solution is that it interpolates between the Veneziano amplitude and a scalar particle amplitude. However, an analytic proof of unitarity of the amplitude is not yet known. In this short note, we explicitly compute the partial wave coefficients on the leading Regge trajectory in D=4. We find that these coefficients always remain positive, even though their magnitude decreases with spin. Since the coefficients on the subleading trajectories are observed to be larger than those on the leading ones, our result indicates the positivity of the full Coon amplitude in D=4.

    ↳ hep-thhep-phJHEP(2022)·32 citations
21. 21*

    From moments of the distribution function to hydrodynamics: The non-conformal case

    Sunil Jaiswal🇮🇳 · Jean-Paul Blaizot🇫🇷 · Rajeev S. Bhalerao🇮🇳 · Zenan Chen🇨🇳 · Amaresh Jaiswal🇮🇳 · Li Yan🇨🇳

    We study the one-dimensional boost-invariant Boltzmann equation in the relaxation-time approximation using special moments of the distribution function for a system with a finite particle mass. The infinite hierarchy of moments can be truncated by keeping only the three lowest moments that correspond to the three independent components of the energy-momentum tensor. We show that such a three-moment truncation reproduces accurately the exact solution of the kinetic equation after a simple renormalization that takes into account the effects of the neglected higher moments. We derive second-order Israel-Stewart hydrodynamic equations from the three-moment equations, and show that, for most physically relevant initial conditions, these equations yield results comparable to those of the three-moment truncation, albeit less accurate. We attribute this feature to the fact that the structure of Israel-Stewart equations is similar to that of the three-moment truncation. In particular, the presence of the relaxation term in the Israel-Stewart equations, yields an early-time regime that mimics approximately the collisionless regime. A detailed comparison of the three-moment truncation with second-order non-conformal hydrodynamics reveals ambiguities in the definition of second-order transport coefficients. These ambiguities affect the ability of Israel-Stewart hydrodynamics to reproduce results of kinetic theory.

    ↳ nucl-thhep-phPRC(2022)·38 citations
22. 22*

    Normal and Quasinormal Modes of Holographic Multiquark Star

    Supakchai Ponglertsakul🇹🇭 · Piyabut Burikham🇹🇭 · Sitthichai Pinkanjanarod🇹🇭

    The quadrupole normal-mode oscillation frequency $f_n$ of multiquark star are computed for $n=1-5$. At the transition from low to high density multiquark in the core region, the first 2 modes jump to larger values, a distinctive signature of the presence of the high-density core. When the star oscillation couples with spacetime, gravitational waves~(GW) will be generated and the star will undergo damped oscillation. The quasinormal modes~(QNMs) of the oscillation are computed using two methods, direct scan and WKB, for QNMs with small and large imaginary parts respectively. The small imaginary QNMs have frequencies $1.5-2.6$ kHz and damping times $0.19-1.7$ secs for multiquark star with mass $M=0.6-2.1M_{\odot }$~(solar mass). The WKB QNMs with large imaginary parts have frequencies $5.98-9.81$ kHz and damping times $0.13-0.46$ ms for $M\simeq 0.3-2.1M_{\odot }$. They are found to be the fluid $f-$modes and spacetime curvature $w-$modes respectively.

    ↳ gr-qcastro-ph.SRhep-phPRD(2023)·5 citations
23. 23*

    Background Modeling for Double Higgs Boson Production: Density Ratios and Optimal Transport

    Tudor Manole🇺🇸 · Patrick Bryant🇺🇸 · John Alison🇺🇸 · Mikael Kuusela🇺🇸 · Larry Wasserman🇺🇸

    We study the problem of data-driven background estimation, arising in the search of physics signals predicted by the Standard Model at the Large Hadron Collider. Our work is motivated by the search for the production of pairs of Higgs bosons decaying into four bottom quarks. A number of other physical processes, known as background, also share the same final state. The data arising in this problem is therefore a mixture of unlabeled background and signal events, and the primary aim of the analysis is to determine whether the proportion of unlabeled signal events is nonzero. A challenging but necessary first step is to estimate the distribution of background events. Past work in this area has determined regions of the space of collider events where signal is unlikely to appear, and where the background distribution is therefore identifiable. The background distribution can be estimated in these regions, and extrapolated into the region of primary interest using transfer learning with a multivariate classifier. We build upon this existing approach in two ways. First, we revisit this method by developing a customized residual neural network which is tailored to the structure and symmetries of collider data. Second, we develop a new method for background estimation, based on the optimal transport problem, which relies on modeling assumptions distinct from earlier work. These two methods can serve as cross-checks for each other in particle physics analyses, due to the complementarity of their underlying assumptions. We compare their performance on simulated double Higgs boson data.

    ↳ stat.APhep-exhep-phphysics.data-an+16 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.