Wed·Aug 16, 2023Wednesday·August 16, 2023

1. 01*

   Decay of entangled fermion pairs with post-selection

   J. A. Aguilar-Saavedra🇪🇸

   We consider a pair of unstable fermions in a spin-entangled state. After the decay of one fermion, a spin measurement is performed on the surviving partner, with a Stern-Gerlach experiment or similar. The measurement not only projects the spin of the surviving fermion, but is also physically equivalent to a spin projection for the decayed one -- even when it no longer exists. This post-selection effect would be experimentally accessible using muon pairs in a maximally-entangled state, produced either in the decay of a scalar particle, or in $e^{+}{e}^{-}$ collisions at wide angles.

   hep-phquant-phPLB(2024)·16 citations
2. 02*

   Global analysis of polarized DIS & SIDIS data with improved small-$x$ helicity evolution

   Daniel Adamiak🇺🇸 · Nicholas Baldonado🇺🇸 · Yuri V. Kovchegov🇺🇸 · W. Melnitchouk🇺🇸 · Daniel Pitonyak🇺🇸 · Nobuo Sato🇺🇸 · Matthew D. Sievert🇺🇸 · Andrey Tarasov🇺🇸 · Yossathorn Tawabutr🇫🇮

   We analyze the world polarized deep-inelastic scattering (DIS) and semi-inclusive DIS (SIDIS) data at low values of $x<0.1$, using small-$x$ evolution equations for the flavor singlet and nonsinglet helicity parton distribution functions (hPDFs). The hPDFs for quarks, antiquarks, and gluons are extracted and evolved to lower values of $x$ to make predictions for the future Electron-Ion Collider (EIC). We improve on our earlier work by employing the more realistic large-$N_c\&N_f$ limit of the revised small-$x$ helicity evolution, and incorporating running coupling corrections along with SIDIS data into the fit. We find an anti-correlation between the signs of the gluon and $C$-even quark hPDFs as well as the $g_1$ structure function. While the existing low-$x$ polarized DIS and SIDIS data are insufficient to constrain the initial conditions for the polarized dipole amplitudes in the helicity evolution equations, future EIC data will allow more precise predictions for hPDFs and the $g_1$ structure function for $x$ values beyond those probed at the EIC. Using the obtained hPDFs, we discuss the contributions to the proton spin from quark and gluon spins at small $x$.

   hep-phhep-exnucl-thPRD(2023)·32 citations
3. 03*

   Neutrino charge radius and electromagnetic dipole moments via scalar and vector leptoquarks

   A. Bolaños-Carrera🇲🇽 · M. Guiot-Lomelí🇲🇽 · G. Tavares-Velasco🇲🇽

   The one-loop contribution of scalar and vector leptoquarks (LQs) to the electromagnetic properties (NEPs) of massive Dirac neutrinos is presented via an effective Lagrangian approach, with emphasis on the effective neutrino charge radius (NCR), which has never been calculated and is obtained by the background field formalism in a Yang-Mills-like scenario for gauge LQs. Analytical results for nonzero neutrino mass are presented in terms of both Feynman-parameter integrals and Passarino-Veltman scalar functions, which can be useful to obtain the NEPs of heavy neutrinos, out of which approximate expressions are obtained for light neutrinos. For the numerical analysis we concentrate on the only renormalizable scalar and vector LQ representations that do not need extra symmetries to forbid tree-level proton decay. Constraints on the parameter space consistent with current experimental data are then discussed and it is found that the LQ representations ${\tilde{R}}_2$ and $U_1$ could yield the largest contributions to the NEPs provided that they have couplings to both left- and right-handed neutrinos of the order of $O(1)$. For a LQ mass of $1.5$ TeV, the magnetic dipole moment (MDM) of the tau neutrino can be of the order of $10^{-9}$ ${\mu }_B$, whereas its neutrino electric dipole moment (EDM) can reach values as high as $10^{-20}$-$10^{-19}$ ecm. On the other hand, the NCR can reach values up to $10^{-35}$ cm${}^2$ regardless of the neutrino flavor and even in the absence of right-handed neutrinos. In the latter scenario, the EDM vanishes and the contribution to neutrino MDM would be negligible, of the order of $10^{-14}$ ${\mu }_B$ for the tau neutrino, whereas those for the muon and electron neutrinos would be about two and seven orders of magnitude smaller, respectively. Our estimates could be severely suppressed due to a possible suppression of the LQ coupling constants.

   hep-phEPJC(2024)·6 citations
4. 04*

   A dynamical holographic QCD model for spontaneous chiral symmetry breaking and confinement

   Alfonso Ballon-Bayona🇧🇷 · Tobias Frederico🇧🇷 · Luis A. H. Mamani🇧🇷 · Wayne de Paula🇧🇷

   In this paper, we present a holographic realization of spontaneous chiral symmetry breaking and confinement. The latter is realized by building a solution of 5d Einstein-dilaton gravity leading to a confining quark antiquark potential. The 4d currents and the quark mass operator associated with chiral symmetry breaking and creation of meson states are mapped to 5d fields whose dynamics is given by a non-Abelian Higgs action. We introduce a non-minimal dilaton coupling to the tachyon potential which has two parameters, one of them controlling the presence or absence of spontaneous chiral symmetry breaking and the other controlling the sign of the chiral condensate as the quark mass grows. We calculate the masses of vector, scalar, axial-vector and pseudoscalar mesons, focusing on the effect of chiral symmetry breaking on the spectrum. In the chiral limit we identify the emergence of a massless state in the pseudoscalar meson spectrum, i.e., the pion. We calculate all meson decay constants and confirm that the pion satisfies the Gell-Mann-Oakes relation in the light quark regime.

   hep-phhep-lathep-thPRD(2023)·15 citations
5. 05*

   Sensitivity to CP Discovery in the Presence of Lorentz Invariance Violating Potential at T2HK/T2HKK

   Supriya Pan (1 and 2)🇮🇳 · Kaustav Chakraborty (1)🇮🇳 · Srubabati Goswami (1) ((1) Physical Research Laboratory, Ahmedabad, (2) Indian Institute of Technology, Gandhinagar)🇮🇳

   Investigation of conservation/violation of CP symmetry in the leptonic sector is very essential in understanding the evolution of the universe. Lorentz invariance and CPT are fundamental symmetries of nature. The violation of Lorentz invariance can also lead to CPT violations. The standard three flavour neutrino oscillation framework presents a scenario to observe the signature of Lorentz invariance and CP violations. This work focuses on the effect of Lorentz invariance violating (LIV) parameters on the sensitivity to CP violation. We investigate the sensitivity in two proposed configurations of the upcoming T2HK experiment: (i) one detector each placed at 295 km and 1100 km, and (ii) two identical detectors at 295 km. This study probes the effect of CPT violating parameters $a_{e\mu },a_{e\tau },a_{\mu \tau }$.

   hep-phhep-exEPJC(2024)·7 citations
6. 06*

   New insights into the nature of the $\Lambda (1380)$ and $\Lambda (1405)$ resonances away from the SU(3) limit

   Feng-Kun Guo🇨🇳 · Yuki Kamiya🇩🇪 · Maxim Mai🇺🇸 · Ulf-G. Meißner🇩🇪

   Starting from the SU(3) limit, we consider the nature of the dynamically generated resonances $\Lambda (1380)$, $\Lambda (1405)$ and $\Lambda (1680)$ as the pion and kaon masses are tuned to their physical values. We show that the accidental symmetry of the two octets due to the leading order Weinberg-Tomozawa term is broken by the next-to-leading order terms. Most interestingly, we observe an interchange of the two trajectories of the $\Lambda (1380)$ and the $\Lambda (1405)$ away from the SU(3) limit at next-to-leading order. This remarkable phenomenon can be investigated using lattice QCD calculations that start from the SU(3) limit.

   hep-phhep-exhep-latnucl-thPLB(2023)·34 citations
7. 07*

   The properties of the $S$-wave $D_s{\bar{D}}_s$ bound state

   Jing-Juan Qi🇨🇳 · Zhen-Yang Wang🇨🇳 · Zhu-Feng Zhang🇨🇳 · Xin-Heng Guo🇨🇳

   In this work, we investigate possible bound states of the $D_s{\bar{D}}_s$ system in the Bethe-Salpeter formalism in the ladder and instantaneous approximations. By numerically solving the Bethe-Salpeter equation with a kernel that includes the contributions from $\varphi$ and $J/\psi$ exchanges, we confirm the existence of a bound state in the $D_s{\bar{D}}_s$ system. We further investigate the partial decay widths of the $D_s{\bar{D}}_s$ bound state into $D\bar{D}$, ${\eta }_c\eta$, and $J/\psi \omega$, finding that these partial widths are sensitive to the parameter $\alpha$ in our model. Notably, we observe that the dominant decay channel for the $D_s{\bar{D}}_s$ bound state is that into $D\bar{D}$.

   hep-phCPC(2026)·5 citations
8. 08*

   Nonleptonic two-body weak decays of charmed baryons

   Chia-Wei Liu🇨🇳

   We analyze the two-body nonleptonic weak decays of charmed baryons, employing the pole approximation in tandem with the $SU(3{)}_F$ symmetry. We are able to make novel predictions for decay channels of ${\Omega }_c^0\to {\mathbf{B}}_{n}P$ and ${\mathbf{B}}_{cc}\to {\mathbf{B}}_c^{A,S}P$ based on the experimental data of ${\mathbf{B}}_c^A\to {\mathbf{B}}_{n}P$. Here, ${\mathbf{B}}_n$, ${\mathbf{B}}_c^A$, ${\mathbf{B}}_c^S$ and ${\mathbf{B}}_{cc}$ are the low-lying octet, antitriplet charmed, sextet charmed and doubly charmed baryons, respectively, and $P$ is the pseudoscalar meson. Our findings reveal that the fitted effective Wilson coefficient ${\mathcal{C}}_{+}=0.469$ is notably smaller than the naive expectation, and the low-lying pole approximation fails to account for $\mathcal{B}({\Lambda }_c^{+}\to n{\pi }^{+},{\Xi }^0{K}^{+})$, despite consistencies with the soft-meson limit. We further recommend the decay channel ${\Xi }_{cc}^{+}\to {\Xi }_c^0{\pi }^{+}\to {\Xi }^{-}{\pi }^{+}{\pi }^{+}{\pi }^{+}{\pi }^{-}$ for exploring evidence of ${\Xi }_{cc}^{+}$, estimating the branching fraction at $(1.1\pm 0.6)\times 10^{-3}$.

   hep-phhep-exPRD(2024)·22 citations
9. 09*

   Current status on pair-produced muon-philic vectorlike leptons in multilepton channels at the LHC

   Junichiro Kawamura🇰🇷 · Seodong Shin🇰🇷

   In this work, we obtain the current limits on the pair production of vectorlike leptons decaying to a Standard Model gauge boson and a lepton in the second generation using the Run-2 data at the LHC. Since there is no dedicated search, we recast the ATLAS analyses searching for the type-III seesaw heavy leptons in the multi-lepton channels. There is no limit for the $SU(2{)}_L$ singlet vectorlike lepton beyond about 100 GeV, while the limit is about 780 GeV for the doublet one. Thus, dedicated searches for the vectorlike leptons are necessary, especially for the singlet one. We also study the general cases of the vectorlike lepton decays and future sensitivities at the HL-LHC.

   hep-phhep-exJHEP(2023)·15 citations
10. 10*

    Renormalization of a Standard Model Extension with a Dark Abelian Sector and Predictions for the W-Boson Mass

    Stefan Dittmaier🇩🇪 · Jonas Rehberg🇩🇪 · Heidi Rzehak🇩🇪

    The described Dark Abelian Sector Model (DASM) extends the Standard Model (SM) by a ``dark'' sector containing a spontaneously broken $U(1{)}_{\text{d}}$ gauge group. Keeping this dark sector quite generic we only add one additional Higgs boson, one Dirac fermion, and right-handed SM-like neutrinos to the SM. Using the only two singlet operators of the SM with dimension less than 4 (the $U(1{)}_{\text{Y}}$ field-strength tensor and the SM Higgs mass operator $|\Phi {|}^2$) as well as the right-handed neutrino fields we open up three portals to the dark sector. Dark sectors, such as the one of the DASM, that introduce an additional Higgs boson $\text{H}$ as well as an additional ${\text{Z}}^{\prime }$ gauge boson can have a large influence on the predictions for electroweak precision observables and even accommodate possible dark matter candidates. We consider one of the two Higgs bosons to be the known $125\text{GeV}$ Higgs boson and parameterize the extension of the scalar sector by the mass of the second Higgs boson, the Higgs mixing angle, and a Higgs self-coupling. We do not assume any mass hierarchy in the gauge sector and use the mass of the additional ${\text{Z}}^{\prime }$ boson and a corresponding gauge-boson mixing angle to parameterize the extension of the gauge sector. The fermion sector is parameterized by the mass of the additional fermion and a fermion mixing angle. We describe an on-shell as well as an $\overline{\text{MS}}$ renormalization scheme for the DASM sectors and give explicit results for the renormalization constants at the 1-loop level, and, thus, prepare the ground for full NLO predictions for collider observables in the DASM. As a first example, we provide the DASM prediction for the W-boson mass derived from muon decay.

    hep-phJHEP(2024)·5 citations
11. 11*

    Cosmic inflation and $(g-2{)}_{\mu }$ in minimal gauged $L_{\mu }-L_{\tau }$ model

    Arnab Paul🇮🇳 · Sourov Roy🇮🇳 · Abhijit Kumar Saha🇮🇳

    The minimal $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge symmetry extended Standard Model (SM) is a well motivated framework that resolves the discrepancy between the theoretical prediction and experimental observation of muon anomalous magnetic moment. We envisage the possibility of identifying the beyond Standard Model Higgs of $U(1{)}_{L_{\mu }-L_{\tau }}$ sector, non-minimally coupled to gravity, as the inflaton in the early universe, while being consistent with the $(g-2{)}_{\mu }$ data. Although the structure seems to be trivial, we observe that taking into consideration of a complete cosmological history starting from inflation through the reheating phase to late-time epoch along with existing constraints on $U(1{)}_{L_{\mu }-L_{\tau }}$ model parameters leave us a small window of allowed reheating temperature. This further results into restriction of $(n_s-r)$ plane which is far severe than the one in a generic non-minimal quartic inflationary set up.

    hep-phastro-ph.COJCAP(2024)·3 citations
12. 12*

    Experimental evidence of dark matter axions identical to solar axions and the absence of the "fifth" carrier force for the Higgs field

    Vitaliy D. Rusov🇺🇦 · Igor V. Sharph🇺🇦 · Vladimir P. Smolyar🇺🇦

    The complete "experimental" proof of the existence of axion luminosity and trapped ADMs in the interior of the Sun is the reason for the formation of hot dark matter axions (see modified Turner model (1987) with a critical density fraction of ${\Omega }_{axionHDM}^{thermal}\sim 0.32$ at a mass of $\sim 6eV$) between inflation and Big Bang nucleosynthesis, which are further transformed into mixed dark matter between Big Bang nucleosynthesis and the cosmological microwave background (CMB) in the form of ${\left[{\Omega }_{axionHDM}^{thermal}\right]}_{\sim 0.32}={\Omega }_{ADM}+{\Omega }_{baryon}$ and ${\left[{\Omega }_{axionHDM}^{thermal}\right]}_{axiogenesis}={\Omega }_{axoinWDM}^{coherent}+{\Omega }_{baryon}$, where the first term 5 GeV ADM is the result of the decay of the partially composite dark matter of the Higgs boson, in which there is a remarkable absence of the "fifth" carrier force for the Higgs field in the Universe, and the second term ${\Omega }_{axoinWDM}^{coherent}\sim 4.5\cdot 10^{-5}$ is associated with the mass of $\sim 3.2\cdot 10^{-2}eV$ of coherent axions of warm dark matter, which are identical to solar axions with the same mass (Rusov et al. 2021).

    hep-ph0 citations
13. 13*

    Cosmic Millicharge Background and Reheating Probes

    Xucheng Gan🇺🇸 · Yu-Dai Tsai🇺🇸

    We demonstrate that the searches for dark sector particles can provide probes of reheating scenarios, focusing on the cosmic millicharge background produced in the early universe. We discuss two types of millicharge particles (mCPs): either with, or without, an accompanying dark photon. These two types of mCPs have distinct theoretical motivations and cosmological signatures. We discuss constraints from the overproduction and mCP-baryon interactions of the mCP without an accompanying dark photon, with different reheating temperatures. We also consider the $\Delta N_{\mathrm{eff}}$ constraints on the mCPs from kinetic mixing, varying the reheating temperature. The regions of interest in which the accelerator and other experiments can probe the reheating scenarios are identified in this paper for both scenarios. These probes can potentially allow us to set an upper bound on the reheating temperature down to $\sim 10$ MeV, much lower than the previously considered upper bound from inflationary cosmology at around $\sim 10^{16}$ GeV. In addition, we find parameter regions in which the two mCP scenarios may be differentiated by cosmological considerations. Finally, we discuss the implications of dedicated mCP searches and future CMB-S4 observations.

    hep-phastro-ph.COgr-qchep-ex+1JHEP(2025)·37 citations
14. 14*

    Uncovering New Higgses in the LHC Analyses of Differential $t\bar{t}$ Cross Sections

    Sumit Banik🇨🇭 · Guglielmo Coloretti🇨🇭 · Andreas Crivellin🇨🇭 · Bruce Mellado🇿🇦

    Statistically significant tensions between the Standard Model (SM) predictions and the measured lepton distributions in differential top cross-sections emerged in LHC Run~1 data and became even more pronounced in Run~2 analyses. Due to the level of sophistication of the SM predictions and the performance of the ATLAS and CMS detectors, this is very remarkable. Therefore, one should seriously consider the possibility that these measurements are contaminated by beyond-the-SM contributions. In this article, we use differential lepton distributions from the latest ATLAS $t\bar{t}$ analysis to study a new physics benchmark model motivated by existing indications for new Higgses: a new scalar $H$ is produced via gluon fusion and decays to $S^{\prime }$ ($95$GeV) and $S$ ($152$GeV), which subsequently decay to $b\bar{b}$ and $WW$, respectively. In this setup, the total ${\chi }^2$ is reduced, compared to the SM, resulting in $\Delta {\chi }^2=34$ to $\Delta {\chi }^2=158$, depending on the SM simulation used. Notably, allowing $m_S$ to vary, the combination of the distributions points towards $m_S\approx 150$GeV which is consistent with the existing $\gamma \gamma$ and $WW$ signals, rendering a mismodelling of the SM unlikely. Averaging the results of the different SM predictions, a non-vanishing cross-section for $pp\to H\to S{S}^{\prime }\to b\bar{b}WW$ of $\approx 13$pb is preferred. If $S^{\prime }$ is SM-like, this cross-section, at the same time explains the $95$GeV $\gamma \gamma$ excess, while the dominance of $S\to WW$ suggests that $S$ is the neutral component of the $SU(2{)}_L$ triplet with hypercharge~0.

    hep-phhep-exJHEP(2025)·36 citations
15. 15*

    Cosmological Implications of Gauged $U(1{)}_{B-L}$ on $\Delta N_{\mathrm{eff}}$ in the CMB and BBN

    Haidar Esseili🇺🇸 · Graham D. Kribs🇺🇸

    We calculate the effects of a light, very weakly-coupled boson $X$ arising from a spontaneously broken $U(1{)}_{B-L}$ symmetry on $\Delta N_{\mathrm{eff}}$ as measured by the CMB and $Y_p$ from BBN. Our focus is the mass range $1\mathrm{eV}\lesssim m_X\lesssim 100\mathrm{MeV}$; masses lighter than about an $\mathrm{eV}$ have strong constraints from fifth-force law constraints, while masses heavier than about 100 MeV are constrained by other probes. We do not assume $X$ began in thermal equilibrium with the SM; instead, we allow $X$ to freeze-in from its very weak interactions with the SM. We find $U(1{)}_{B-L}$ is more strongly constrained by $\Delta N_{\mathrm{eff}}$ than previously considered. The bounds arise from the energy density in electrons and neutrinos slowly siphoned off into $X$ bosons, which become nonrelativistic, redshift as matter, and then decay, dumping their slightly larger energy density back into the SM bath causing $\Delta N_{\mathrm{eff}}>0$. While some of the parameter space has complementary constraints from stellar cooling, supernova emission, and terrestrial experiments, we find future CMB observatories can access regions of mass and coupling space not probed by any other method. In gauging $U(1{)}_{B-L}$, we assume the $[U(1{)}_{B-L}{]}^3$ anomaly is canceled by right-handed neutrinos, and so our $\Delta N_{\mathrm{eff}}$ calculations have been carried out in two scenarios: neutrinos have Dirac masses, or, right-handed neutrinos acquire Majorana masses. In the latter scenario, we comment on the additional implications of thermalized right-handed neutrinos decaying during BBN. We also briefly consider the possibility that $X$ decays into dark sector states. If these states behave as radiation, we find weaker constraints, whereas if they are massive, there are stronger constraints, though now from $\Delta N_{\mathrm{eff}}<0$.

    hep-phastro-ph.COJCAP(2024)·25 citations
16. 16*

    Complete $N_f^2$ contributions to four-loop pure-singlet splitting functions

    Thomas Gehrmann🇨🇭 · Andreas von Manteuffel🇩🇪 · Vasily Sotnikov🇨🇭 · Tong-Zhi Yang🇨🇭

    The scale evolution of parton distributions is determined by universal splitting functions. As a milestone towards the computation of these functions to four-loop order in QCD, we compute all contributions to the pure-singlet quark-quark splitting functions that involve two closed fermion loops. The splitting functions are extracted from the pole terms of off-shell operator matrix elements, and the workflow for their calculation is outlined. We reproduce known results for the non-singlet four-loop splitting functions and validate our new pure-singlet results against fixed Mellin moments.

    hep-phhep-thnucl-thJHEP(2024)·49 citations
17. 17*

    Analytic and Parameter-Free Formula for the Neutrino Mixing Matrix

    Bodo Lampe🇩🇪

    A parameter-free analytic expression for the PMNS matrix is derived which fits numerically all the measured matrix components at 99.7$\%$ confidence. Results are proven within the microscopic model and include a prediction of the leptonic Jarlskog invariant. The approach is universal in the sense that it can be applied to the quark sector as well. Preliminary numbers obtained for the CKM matrix elements look promising, but are plagued with large theoretical errors.

    hep-ph2 citations
18. 18*

    The two-loop power spectrum in redshift space

    Petter Taule🇫🇷 · Mathias Garny🇩🇪

    We present the matter power spectrum in redshift space including two-loop corrections. We follow a strictly perturbative approach incorporating all non-linearities entering both via the redshift-space mapping and within real space up to the required (fifth) order, complemented by suitable effective field theory (EFT) corrections. This approach can a priori be viable up to scales of order $0.2h{\mathrm{Mpc}}^{-1}$ beyond which power suppression related to the finger-of-God effect becomes non-perturbatively strong. We extend a simplified treatment of EFT corrections at two-loop order from real to redshift space, making sure that the leading UV-sensitivity of both the single-hard and double-hard limit of the two-loop contributions to the power spectrum is accounted for, and featuring two free parameters for each multipole. Taking also infrared-resummation into account, we calibrate with and compare to Quijote $N$-body simulations for the monopole and quadrupole at redshifts $z=0$ and $z=0.5$. We find agreement within sample variance (at percent-level) up to $0.18h{\mathrm{Mpc}}^{-1}$ at two-loop order, compared to $0.1h{\mathrm{Mpc}}^{-1}$ at one-loop. We also investigate the role of higher-derivative corrections.

    ↳ astro-ph.COhep-phJCAP(2023)·14 citations
19. 19*

    Open Quantum Systems with Kadanoff-Baym Equations

    Tim Neidig🇩🇪 · Jan Rais🇩🇪 · Marcus Bleicher🇩🇪 · Hendrik van Hees🇩🇪 · Carsten Greiner🇩🇪

    We study the temporal evolution of quantum mechanical fermionic particles exhibiting one bound state within a one-dimensional attractive square-well potential in a heat bath of bosonic particles. For this open quantum system we formulate the non-equilibrium Kadanoff-Baym equations for the system particles by taking the interactions to be elastic 2-2 scatterings with the heat-bath particles. The corresponding spatially imhomogeneous integro-differential equations for the one-particle Greens's function are solved numerically. We demonstrate how the system particles equilibrate and thermalize with the heat bath and how the off-diagonal elements of the density matrix, expressed in the one-particle energy eigenbasis, decohere, so that only the diagonal entries, i.e. the occupation numbers, survive. In addition, the time evolution of the (retarded) Green's function also determines the spectral properties of the various one-particle quantum states.

    ↳ nucl-thhep-phquant-phPLB(2024)·9 citations
20. 20*

    Joint measurement of the ultra-high-energy neutrino spectrum and cross section

    Victor B. Valera🇩🇰 · Mauricio Bustamante🇩🇰 · Olga Mena🇪🇸

    Soon, a new generation of neutrino telescopes, presently under planning, will target the discovery of ultra-high-energy (UHE) neutrinos of cosmic origin, with energies higher than 100 PeV, that promise unique insight into astrophysics and particle physics. Yet, predictions of the UHE neutrino flux and interaction cross section -- whose measurement is co-dependent -- are laden with significant uncertainty that, if unaddressed, could misrepresent the capabilities to measure one or the other. To address this, we advocate for the joint measurement of the UHE neutrino spectrum and neutrino-nucleon cross section, including of their energy dependence, without assuming prior knowledge of either. We illustrate our methods by adopting empirical parametrizations of the neutrino spectrum, in forecasts geared to the planned radio array of the IceCube-Gen2 neutrino telescope. We warn against using simple parametrizations -- a simple power law or one augmented with an exponential cut-off -- that might fail to capture features of the spectrum that are commonplace in the predictions. We argue instead for the use of flexible parametrizations -- a piecewise power law or an interpolating polynomial -- that ensure accuracy. We report loose design targets for the detector energy and angular resolution that are compatible with those under present consideration.

    ↳ astro-ph.HEhep-exhep-ph6 citations
21. 21*

    $\eta$ and ${\eta }^{\prime }$ mesons in nuclear matter and nuclei

    J.J Cobos-Martinez🇲🇽 · Kazuo Tsushima🇧🇷

    We present updated and extended results for the $\eta$- and ${\eta }^{\prime }$-nucleus bound state energies, obtained by solving the Schrödinger and Klein-Gordon equations with complex optical potentials, for a wide range of nuclei. The $\eta$ and ${\eta }^{\prime }$ nuclear potentials are obtained in the local density approximation from the mass shift of these mesons in nuclear matter, which is calculated within the quark-meson coupling model. Our results show that the $\eta$ and ${\eta }^{\prime }$ mesons are expected to form mesic nuclei with all the nuclei considered. However, the signal for the formation of the $\eta$- and ${\eta }^{\prime }$-mesic nuclei may be difficult to identify experimentally due to possible large widths.

    ↳ nucl-thhep-phPRC(2024)·12 citations
22. 22*

    Ultra-low mass PBHs in the early universe can explain the PTA signal

    Nilanjandev Bhaumik🇮🇳 · Rajeev Kumar Jain🇮🇳 · Marek Lewicki🇵🇱

    Pulsar Timing Array collaborations have recently announced the discovery of a stochastic gravitational wave background (SGWB) at nanohertz frequencies. We analyze the GW signals from the domination of ultra-low mass primordial black holes (PBHs) in the early universe and show that they can explain this recent discovery. This scenario requires a relatively broad peak in the power spectrum of scalar perturbations from inflation with a spectral index in a narrow range of $1.45$ to $1.6$. The resulting PBH population would have mass around $10^8$g, and the initial abundance ${\beta }_f$ lies between $10^{-10}$ and $10^{-9}$. We find that this explanation is preferred by the data over the generic model, assuming supermassive BHs as the source. These very light PBHs would decay before Big Bang Nucleosynthesis (BBN); however, upcoming third-generation terrestrial laser interferometers would be able to test the model by observing the GW spectrum produced during the formation of the PBHs. Also, the scalar power spectra associated with our scenario will be within the reach of PIXIE probing CMB spectral distortions.

    ↳ astro-ph.COgr-qchep-phPRD(2023)·57 citations
23. 23*

    Thermodynamics of quark matter with multiquark clusters in an effective Beth-Uhlenbeck type approach

    D. Blaschke🇵🇱 · M. Cierniak🇵🇱 · O. Ivanytskyi🇵🇱 · G. Röpke🇵🇱

    We describe multiquark clusters in quark matter within a Beth-Uhlenbeck approach in a background gluon field coupled to the underlying chiral quark dynamics using the Polyakov gauge which establishes the center symmetry of color SU(3) that suppresses colored states as an aspect of confinement. Quark confinement is modeled by a large quark mass in vacuum motivated by a confining density functional approach. A multiquark cluster containing $n$ quarks and antiquarks is described as a binary composite of smaller subclusters $n_1$ and $n_2$ ($n_1+n_2=n$). It has a spectrum consisting of a bound state and a scattering state continuum. For the corresponding cluster-cluster phase shifts we discuss simple ansätze that capture the Mott dissociation of clusters as a function of temperature and chemical potential. We go beyond the simple "step-up-step-down" model that ignores continuum correlations and introduce an improved model that includes them in a generic form. In order to explain the model, we restrict ourselves here to the cases where the cluster size is $1\le n\le 6$. A striking result is the suppression of the abundance of colored multiquark clusters at low temperatures by the coupling to the Polyakov loop and their importance for a quantitative description of lattice QCD thermodynamics at non-vanishing baryochemical potentials. An important ingredient are Polyakov-loop generalized distribution functions of $n$-quark clusters which are derived here for the first time. Within our approach we calculate thermodynamic properties such as baryon density and entropy. We demonstrate that the limits of a hadron resonance gas at low temperatures and $\mathcal{O}(g^2)$ perturbative QCD at high temperatures are correctly reproduced. A comparison with lattice calculations shows that our model is able to give a unified, systematic approach to describe properties of the quark-gluon-hadron system.

    ↳ nucl-thhep-phEPJA(2024)·11 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.