Wed·Jun 29, 2022Wednesday·June 29, 2022

1. 01*

   Concealing Dirac neutrinos from cosmic microwave background

   Anirban Biswas🇰🇷 · Dilip Kumar Ghosh🇮🇳 · Dibyendu Nanda🇰🇷

   The existence of prolonged radiation domination prior to the Big Bang Nucleosynthesis (BBN), starting just after the inflationary epoch, is not yet established unanimously. If instead, the universe undergoes a non-standard cosmological phase, it will alter the Hubble expansion rate significantly and may also generate substantial entropy through non-adiabatic evolution. This leads to a thumping impact on the properties of relic species decoupled from the thermal bath before the revival of the standard radiation domination in the vicinity of the BBN. In this work, considering the Dirac nature of neutrinos, we have studied decoupling of ultra-relativistic right-handed neutrinos (${\nu }_R$s) in presence of two possible non-standard cosmological phases. While in both cases we have modified Hubble parameters causing faster expansions in the early universe, one of the situations predicts a non-adiabatic evolution and thereby a slower redshift of the photon temperature due to the expansion. Considering the most general form of the collision term with Fermi-Dirac distribution and Pauli blocking factors, we have solved the Boltzmann equation numerically to obtain $\Delta {\mathrm{N}}_{\mathrm{eff}}$ for the three right-handed neutrinos. We have found that for a large portion of parameter space, the combined effect of early decoupling of ${\nu }_R$ as well as the slower redshift of photon bath can easily hide the signature of right-handed neutrinos, in spite of precise measurement of $\Delta {\mathrm{N}}_{\mathrm{eff}}$, at the next generation CMB experiments like CMB-S4, SPT-3G etc. This however will not be applicable for the scenarios with only fast expansion.

   hep-phastro-ph.COJCAP(2022)·21 citations
2. 02*

   Heavy Neutral Leptons at Beam Dump Experiments of Future Lepton Colliders

   Pierce Giffin🇺🇸 · Stefania Gori🇺🇸 · Yu-Dai Tsai🇺🇸 · Douglas Tuckler🇨🇦

   A new beam dump experiment that utilizes the beam of future high energy electron-positron colliders could be an excellent avenue to search for dark sector particles due to its unprecedented high energy and intensity. We consider heavy neutral leptons (HNLs) as a specific example to demonstrate the sensitivity of searches for dark sector particles at future electron-positron collider beam dump experiments. This includes the study of the reach at the International Linear Collider (ILC), the Cool Copper Collider (${\mathrm{C}}^3$), and the Compact Linear Collider (CLIC). We comprehensively examine the HNL production and detector acceptance at these electron beam dump experiments. We show that these experiments will probe a large range of HNL parameter space, not yet probed by past experiments. These experiments will be complementary to other proposed experiments such as proton beam dump experiments, neutrino experiments, and LHC auxiliary detectors. Our study also motivates a more detailed analysis of heavy meson productions in high-energy electron-nucleon collisions in thick targets.

   hep-phJHEP(2023)·15 citations
3. 03*

   Understanding the QCD medium by the diffusion of charm quarks using a Color String Percolation Model

   Kangkan Goswami🇮🇳 · Dushmanta Sahu🇮🇳 · Raghunath Sahoo🇮🇳

   We study the drag and diffusion coefficients of the charm quark in the deconfined matter produced in the ultra-relativistic collisions by taking the Color String Percolation Model (CSPM) approach. CSPM, being a QCD-inspired model, can give us essential information about the hot and dense system produced in ultra-relativistic collisions. With the information on initial percolation temperature and percolation density, we estimate the relaxation time (${\tau }_c$), drag coefficient ($\gamma$), transverse momentum diffusion coefficient ($B_0$), and spatial diffusion coefficient ($D_s$) of charm quark inside a deconfined medium. Finally, we compare the obtained results with lattice QCD and with various other theoretical models. A good agreement can be observed between the results obtained from CSPM and lattice QCD.

   hep-phhep-exnucl-exnucl-thPRD(2023)·13 citations
4. 04*

   A global QCD analysis of diffractive parton distribution function considering higher twist corrections within the xFitter framework

   Maral Salajegheh🇩🇪 · Hamzeh Khanpour🇮🇷 · Ulf-G Meißner🇩🇪 · Hadi Hashamipour🇮🇷 · Maryam Soleymaninia🇮🇷

   We present {\tt SKMHS22}, a new set of diffractive parton distribution functions (PDFs) and their uncertainties at next-to-leading-order accuracy in perturbative QCD within the {\tt xFitter} framework. We describe all available diffractive DIS data sets from HERA and the most recent high-precision H1/ZEUS combined measurements considering three different scenarios. First, we extract the diffractive PDFs considering the standard twist-2 contribution. Then, we include the twist-4 correction from the longitudinal virtual photons. Finally, the contribution of subleading Reggeon exchange to the structure-function $F_2^D$ is also examined. For the contribution of heavy flavors, we utilize the Thorne-Roberts general mass variable number scheme. We show that for those corrections, in particular, the twist-4 contribution allows to include the high-$\beta$ region and leads to a better description of the diffractive DIS data sets. We find that the inclusion of the subleading Reggeon exchange significantly improves the description of the diffractive DIS cross-section measurements. The resulting sets are in good agreement with all diffractive DIS data analyzed, which cover a wider kinematical range than in previous fits. The {\tt SKMHS22} diffractive PDFs sets presented in this work are available via the {\tt LHAPDF} interface. We also make suggestions for future research in this area.

   hep-phhep-exPRD(2022)·11 citations
5. 05*

   Neutrinos and their interactions with matter

   M. Sajjad Athar🇮🇳 · A. Fatima🇮🇳 · S. K. Singh🇮🇳

   We have presented a review of the properties of neutrinos and their interactions with matter. The different (anti)neutrino processes like the quasielastic scattering, inelastic production of mesons and hyperons, and the deep inelastic scattering from the free nucleons are discussed and the results for the scattering cross sections are presented. The polarization observables for the leptons and hadrons produced in the final state, in the case of quasielastic scattering, are also studied. The importance of nuclear medium effects in the low, intermediate and high energy regions, in the above processes along with the processes of the coherent neutrino-nucleus scattering, coherent meson production, and trident production, have been highlighted. In some cases the results of the cross sections are also given and compared with the available experimental data as well as with the predictions in the different theoretical models. This study would be helpful in understanding the (anti)neutrino interaction cross section with matter in the few GeV energy region relevant to the next generation experiments like DUNE, Hyper-Kamiokande, and other experiments with accelerator and atmospheric neutrinos. We have emphasized the need of better theoretical models for some of these processes for studying the nuclear medium effects in nuclei.

   hep-phhep-exnucl-thPPNP(2023)·72 citations
6. 06*

   Pseudoscalar charmonium pair interactions via the Pomeron exchange mechanism

   Chang Gong🇨🇳 · Meng-Chuan Du🇨🇳 · Qiang Zhao🇨🇳

   Following the observation of the fully-heavy tetraquark candidates $X(6900)$ and possible $X(6300)$ in the di-$J/\psi$ spectrum by the LHCb Collaboration, we investigate the near-threshold dynamics of the pseudoscalar quarkonium pairs in a coupled-channel approach in the di-${\eta }_c$ channel. We show that the Pomeron exchange mechanism should be a general dynamics in the near-threshold heavy quarkonium pair interactions. In the di-${\eta }_c$ channel, a coupled-channel system involving the di-${\eta }_c$, ${\eta }_c$-${\eta }_c(2S)$ and di-${\eta }_c(2S)$ interactions can be established. Their $S$-wave interactions near threshold via the Pomeron exchange potential can produce near-threshold resonance poles similar to the di-$J/\psi$, $J/\psi$-$\psi (2S)$ and di-$\psi (2S)$ coupled channels. Interestingly, we find here that the pole positions are more shifted to the corresponding thresholds and turn out to be different from those seen in the di-$J/\psi$ spectrum. Taking into account the suppression of the heavy quark spin flips in the transitions between two vector and two pseudoscalar heavy quarkonium systems, the enhancements in the di-${\eta }_c$ spectrum should be different from those seen in the di-$J/\psi$ channel. Experimental study of the di-${\eta }_c$ channel should be useful for disentangling the nature of the fully-heavy tetraquark systems.

   hep-phhep-exPRD(2022)·19 citations
7. 07*

   Quantum speed of evolution of neutral mesons

   Subhashish Banerjee🇮🇳 · K. G. Paulson🇮🇳

   We investigate the quantum-mechanical time-evolution speed limit for neutral $K$ and $B$ mesons, both single as well as correlated, within the framework of open quantum systems. The role of coherence--mixing, a crucial feature of the open system evolution of the underlying quantum systems (here, the mesons), on the quantum-mechanical time-evolution speed limit is studied. The impact of decoherence and CP (charge conjugation parity) symmetry violation on quantum-mechanical time-evolution speed limit is also investigated. The quantum-mechanical time-evolution speed limit increases with the evolution time for the single mesons, a signature of the underlying open system dynamics of the evolution being semi-group in nature. The evolution of the correlated mesons slows down for an evolution time of approximately one-fourth of the lifetime, after which it is sped up. An overall pattern that emerges is that correlated mesons evolve faster as compared to their uncorrelated counterparts, suggesting that quantum correlations can speed up evolution.

   hep-phquant-phEur.Phys.J.Plus(2023)·4 citations
8. 08*

   Investigating Lorentz Violation with the long baseline experiment P2O

   Nishat Fiza🇮🇳 · Nafis Rezwan Khan Chowdhury🇪🇸 · Mehedi Masud🇰🇷

   One of the basic propositions of quantum field theory is Lorentz invariance. The spontaneous breaking of Lorentz symmetry at a high energy scale can be studied at low energy extensions like the Standard model in a model-independent way through effective field theory (EFT). The present and future Long-baseline neutrino experiments can give a scope to observe such a Planck-suppressed physics of Lorentz invariance violation (LIV). A proposed long baseline experiment, Protvino to ORCA (dubbed "P2O") with a baseline of 2595 km, is expected to provide good sensitivities to unresolved issues, especially neutrino mass ordering. P2O can offer good statistics even with a moderate beam power and runtime, owing to the very large ($\sim 6$ Mt) detector volume at KM3NeT/ ORCA. Here we discuss in detail, how the individual LIV parameters affect neutrino oscillations at P2O and DUNE baselines at the level of probability and derive analytical expressions to understand interesting degeneracies and other features. We estimate $\Delta {\chi }^2$ sensitivities to the LIV parameters, analyzing their correlations among each other, and also with the standard oscillation parameters. We calculate these results for P2O alone and also carry out a combined analysis of P2O with DUNE. We point out crucial features in the sensitivity contours and explain them qualitatively with the help of the relevant probability expressions derived here. Finally, we estimate constraints on the individual LIV parameters at $95\%$ confidence level (C.L.) intervals stemming from the combined analysis of P2O and DUNE datasets and highlight the improvement over the existing constraints. We also find out that the additional degeneracy induced by the LIV parameter $a_{ee}$ around $-22\times 10^{-23}$ GeV is lifted by the combined analysis at $95\%$ C.L.

   hep-phhep-exJHEP(2023)·15 citations
9. 09*

   The $\{\beta \}$-expansion for Adler function, Bjorken Sum Rule, and the Crewther-Broadhurst-Kataev relation at order $O({\alpha }_s^4)$

   P. A. Baikov🇷🇺 · S. V. Mikhailov🇷🇺

   We derive explicit expressions for the elements of the $\{\beta \}$-expansion for the nonsinglet Adler $D_A$-function and Bjorken polarized sum rules $S^{Bjp}$ in the N${}^4$LO using recent results by Chetyrkin for these quantities computed within extended QCD including any number of fermion representations. We discuss the properties of the $\{\beta \}$-expansion for $D_A$ and $S^{Bjp}$ at higher orders which follow from the Crewther [1] and the Broadhurst-Kataev [2] relation.

   hep-phJHEP(2023)·7 citations
10. 10*

    Six-meson amplitude in QCD-like theories

    Johan Bijnens🇸🇪 · Tomáš Husek🇸🇪 · Mattias Sjö (Lund U.)🇸🇪

    We calculate the relativistic six-meson scattering amplitude at low energy within the framework of QCD-like theories with $n$ degenerate quark flavors at next-to-leading order in the chiral counting. We discuss the cases of complex, real and pseudo-real representations, i.e. with global symmetry and breaking patterns $\text{SU}(n)\times \text{SU}(n)/\text{SU}(n)$ (extending the QCD case), $\text{SU}(2n)/\text{SO}(2n)$, and $\text{SU}(2n)/\text{Sp}(2n)$. In case of the one-particle-irreducible part, we obtain analytical expressions in terms of 10 six-meson subamplitudes based on the flavor and group structures. We extend on our previous results obtained within the framework of the $\text{O}(N+1)/\text{O}(N)$ non-linear sigma model, with $N$ being the number of meson flavors. This work allows for studying a number of properties of six-particle amplitudes at one-loop level.

    hep-phhep-lathep-thPRD(2022)·13 citations
11. 11*

    Superluminal Propagation on a Moving Braneworld

    Brian Greene🇺🇸 · Daniel Kabat🇺🇸 · Janna Levin🇺🇸 · Arjun S. Menon🇺🇸

    We consider a braneworld scenario in the simplest setting, $M_4\times S^1$, with a 4D Minkowski metric induced on the brane, and establish the possibility of superluminal propagation. If the brane is at rest, the 4D Lorentz symmetry of the brane is exact, but if the brane is in motion, it is broken globally by the compactification. By measuring bulk fields, an observer on the brane sees a slice through a higher-dimensional field profile, which carries an imprint of the extra dimensions even when the brane is at rest. If the brane is in motion we find that bulk fields can propagate outside the brane lightcone by a parametrically large amount set by the brane velocity. We mention observational tests and possible applications to cosmology.

    ↳ hep-thhep-phPRD(2022)·12 citations
12. 12*

    Hyperon productions from Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV

    Purabi Ghosh🇮🇳 · Sushant K. Singh🇮🇳 · Santosh K. Agarwalla🇮🇳 · Jajati K. Nayak🇮🇳

    We evaluate centrality dependence of hyperon, $\Lambda ,\Xi ,\Omega$ and $K$ meson yields from Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV using rate equation and compare with experimental observations. An increase in the yield per participating nucleon is observed with centrality. Higher rate of multistrange productions compared to single-strange are also observed in case of central collisions. Using rate equation or momentum integrated Boltzmann equation we discuss the yield microscopically which are then normalised with thermal pions to get the yield ratio,($H_s+\overline{H_s}$)/(${\pi }^{+}+{\pi }^{-}$) at various centralities. We have also evaluated the relative yield of anti hyperons per participant at various centralities and compared with observations made at RHIC. Increase in the rate of $\Xi$ yield compared to $\Lambda$ is realised in most central collisions. We find multi strange $\Xi ,\Omega$ freeze-out at a temperature very close to $T_c$ and $\Lambda ,K$ do little later.

    ↳ nucl-thhep-exhep-phnucl-ex0 citations
13. 13*

    Instantons: thick-wall approximation

    V. F. Mukhanov🇩🇪 · A. S. Sorin🇷🇺

    We develop a new method for estimating the decay probability of the false vacuum via regularized instantons. Namely, we consider the case where the potential is either unbounded from below or the second minimum corresponding to the true vacuum has a depth exceeding the height of the potential barrier. In this case, the materialized bubbles dominating the vacuum decay naturally have a thick wall and the thin-wall approximation is not applicable. We prove that in such a case the main contribution to the action determining the decay probability comes from the part of the solution for which the potential term in the equation for instantons can be neglected compared to the friction term. We show that the developed approximation exactly reproduces the leading order results for the few known exactly solvable potentials. The proposed method is applied to generic scalar field potentials in an arbitrary number of dimensions.

    ↳ hep-thgr-qchep-phmath-ph+2JHEP(2022)·2 citations
14. 14*

    A reassessment of nuclear effects in muonic deuterium using pionless effective field theory at N3LO

    Vadim Lensky (JGU Mainz)🇩🇪 · Franziska Hagelstein (JGU Mainz and PSI Villigen)🇩🇪 · Vladimir Pascalutsa (JGU Mainz)🇩🇪

    We provide a systematic assessment of the order-${\alpha }^5$ nuclear contributions to the Lamb shift of muonic deuterium, including the accompanying radiative corrections due to vacuum polarization, up to next-to-next-to-next-to-leading order (N3LO) within the pionless effective field theory (EFT). We also evaluate higher-order corrections due to the single-nucleon structure, which are expected to be the most important corrections beyond N3LO. We find a correlation between the deuteron charge and Friar radii, which can be useful to judge the quality of charge form factor parametrisations. We refine the theoretical description of the $2\gamma$-exchange contribution, especially in the elastic contribution and the radiative corrections, ameliorating the original discrepancy between theory and experiment in the size of $2\gamma$-exchange effects. Based on the experimental Lamb shift of muonic deuterium, we obtain the deuteron charge radius, $r_d(\mu \text{D})=2.12763(13{)}_{\text{exp}}(77{)}_{\text{theory}}$~fm, which is consistent with (but less precise than) the value obtained by combining the H-D isotope shift with the muonic hydrogen Lamb shift. The theory uncertainty is evaluated using a Bayesian procedure and is dominated by the truncation of the pionless EFT series.

    ↳ nucl-thhep-phnucl-exphysics.atom-phPLB(2022)·8 citations
15. 15*

    Palatini $R^2$ Quintessential Inflation

    Konstantinos Dimopoulos🇬🇧 · Alexandros Karam🇪🇪 · Samuel Sánchez López🇬🇧 · Eemeli Tomberg🇪🇪

    We construct a model of quintessential inflation in Palatini $R^2$ gravity employing a scalar field with a simple exponential potential and coupled to gravity with a running non-minimal coupling. At early times, the field acts as the inflaton, while later on it becomes the current dark energy. Combining the scalar sector with an ideal fluid, we study the cosmological evolution of the model from inflation all the way to dark energy domination. We interpret the results in the Einstein frame, where a coupling emerges between the fluid and the field, feeding energy from the former to the latter during the matter-dominated era. We perform a numerical scan over the parameter space and find points that align with observations for both the inflationary CMB data and the late-time behaviour. The final dark energy density emerges from an interplay between the model parameters, without requiring the extreme fine-tuning of the cosmological constant in $\Lambda$CDM.

    ↳ gr-qcastro-ph.COhep-phhep-thJCAP(2022)·52 citations
16. 16*

    Probing parity-odd bispectra with anisotropies of GW $V$ modes

    Giorgio Orlando🇳🇱

    It is well known that non-trivial squeezed tensor bispectra can lead to anisotropies in the inflationary stochastic gravitational wave (GW) background, providing us with an alternative and complementary window to primordial non-Gaussianities (NGs) with respect to the CMB. Previous works have highlighted the detection prospects of parity-even tensor NGs via the GW $I$-mode anisotropies. In this work we extend this by analysing for the first time the additional information carried by GW $V$-mode anisotropies due to squeezed NGs. We show that GW $V$ modes allow us to probe parity-odd squeezed $⟨\mathrm{tts}⟩$ and $⟨\mathrm{ttt}⟩$ bispectra. These bispectra break parity at the non-linear level and can be introduced by allowing alternative symmetry breaking patterns during inflation, like those comprised in solid inflation. Considering a BBO-like experiment, we find that a non-zero detection of squeezed $⟨\mathrm{tts}⟩$ parity-odd bispectra in the $V$ modes dipole is possible without requiring any short-scale enhancement of the GW power spectrum amplitude over the constraints set by the CMB. We also briefly discuss the role of $V$-CMB cross-correlations. Our work can be extended in several directions and motivates a systematic search for polarized GW anisotropies in the next generations of GW experiments.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2022)·23 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.