Fri·Mar 31, 2023Friday·March 31, 2023

1. 01*

   Finemensch Lectures on the Strong Interactions

   Robert P. Finemensch🇺🇸 · Gerald X. Gilbert-Thorple🇺🇸

   These twenty-two lectures, with exercises, comprise the extent of what was meant to be a full-year graduate-level course on the strong interactions and QCD, given at Pactech in 19$xx$-$xy$. The course was cut short by the illness that led to Finemensch's death. Several of the lectures were finalized in collaboration with Finemensch for an anticipated monograph based on the course. The others, while retaining Finemensch's idiosyncrasies, are revised similarly to those he was able to check. His distinctive approach and manner of presentation are manifest throughout. Near the end he suggests a novel, nonperturbative formulation of quantum field theory in $D$ dimensions. Supplementary material is provided in appendices and ancillary files, including verbatim transcriptions of three lectures and the corresponding audiotaped recordings.

   hep-phphysics.hist-ph0 citations
2. 02*

   LePDF: Standard Model PDFs for High-Energy Lepton Colliders

   Francesco Garosi🇮🇹 · David Marzocca🇮🇹 · Sokratis Trifinopoulos🇺🇸

   The emission of collinear radiation off an elementary lepton can be factorised from the hard scattering process by introducing Parton Distribution Functions of a Lepton (LePDF), which, contrary to protons, can be derived from first principles. In case of multi-TeV lepton colliders, such as the muon colliders currently being proposed, the complete structure of Standard Model interactions must be taken into account. In this work we solve numerically the corresponding DGLAP equations at the double-log order and provide public files with LePDFs for both muons and electrons, including polarisation effects. We discuss several interesting aspects of the resulting PDFs and compare them with the Effective Vector Approximation, showing that the latter fails to describe well the vector bosons PDFs at small momentum fractions, unless it is extended to higher orders.

   hep-phhep-exJHEP(2023)·60 citations
3. 03*

   Towards the one loop IR/UV dictionary in the SMEFT: one loop generated operators from new scalars and fermions

   G. Guedes🇩🇪 · P. Olgoso🇪🇸 · J. Santiago🇪🇸

   Effective field theories offer a rationale to classify new physics models based on the size of their contribution to the effective Lagrangian, and therefore to experimental observables. A complete classification can be obtained, at a fixed order in perturbation theory, in the form of IR/UV dictionaries. We report on the first step towards the calculation of the one loop, dimension 6 IR/UV dictionary in the SMEFT. We consider dimension-six operators in the SMEFT that cannot be generated at tree level in weakly coupled extensions of the Standard Model. This includes operators with three gauge field strength tensors, operators with two field strength tensors and two scalar fields and dipole operators. We provide a complete classification of renormalizable extensions of the Standard Model with new scalar and fermion fields that contribute to these operators at one loop order, together with their explicit contribution. Our results are encoded in a \texttt{Mathematica} package called \texttt{SOLD} (SMEFT One Loop Dictionary), which includes further functionalities to facilitate the calculation of the complete tree level and one loop matching of any relevant model via an automated interface to \texttt{matchmakereft}. All operators in our list are indeed generated at the one loop order in the extensions considered with the exception of CP-violating ones with three field-strength tensors.

   hep-phSciPost Phys.(2023)·55 citations
4. 04*

   Hermitian Matrix Diagonalization and its Symmetry Properties

   S. H. Chiu🇹🇼 · T. K. Kuo🇺🇸

   A hermitian matrix can be parametrized by a set consisting of its determinant and the eigenvalues of its submatrices. We established a group of equations which connect these variables with the mixing parameters of diagonalization. These equations are simple in structure and manifestly invariant in form under the symmetry operations of dilatation, translation, rephasing and permutation. When applied to the problem of neutrino oscillation in matter they produced two new ``matter invariants" which are confirmed by available data.

   hep-phAdv.High Energy Phys.(2024)·0 citations
5. 05*

   Annihilation of singlet fermionic dark matter into two photons via pseudo-scalar mediator

   M.M. Ettefaghi🇮🇷 · R. Moazzemi🇮🇷 · M. Yazdani Najafabadi🇮🇷

   We consider the indirect detection of dark matter within an extension of the standard model (SM) including a singlet fermion as cold dark matter (CDM) and a singlet pseudo-scalar as a mediator between dark matter and the SM particles. The annihilation cross section of the CDM into two monochromatic photons is calculated and compared with the latest H.E.S.S. data. Although for dark matter masses below 1 TeV the predicted observable cross sections are far from the sensitivity of the recent gamma-ray experiments, it can be comparable to the strongest H.E.S.S. upper bounds for some models with more massive CDM.

   hep-phEPL(2023)·0 citations
6. 06*

   Inclusive $|V_{cb}|$ determination in $\overline{\mathrm{MS}}$ mass scheme using dual-space-renormalon-subtraction method

   Yuuki Hayashi🇯🇵 · Go Mishima🇯🇵 · Yukinari Sumino🇯🇵 · Hiromasa Takaura🇯🇵

   We determine $|V_{cb}|$ from the inclusive semileptonic decay width of the $B$ meson with the known N${}^3$LO perturbative coefficients for the first time in the $\overline{\mathrm{MS}}$ mass scheme. We make use of a recently developed method, dual-space-renormalon-subtraction (DSRS) method, to separate and subtract the order ${\Lambda }_{\mathrm{QCD}}^2/m_b$ infrared renormalon. This allows us to perform the analysis accurately in the $\overline{\mathrm{MS}}$ mass scheme, in which otherwise the perturbative series does not converge well up to the currently calculated perturbation order. Our result reads $|V_{cb}|=0.0415{(}_{-12}^{+10})$, which is consistent with the previous results based on other mass schemes and showing an independent cross check of the current theoretical evaluation of the inclusive decay width.

   hep-phPRD(2023)·3 citations
7. 07*

   Production of cumulative pions and percolation of strings

   M.A.Braun🇷🇺

   Production of pions in high-energy collisions with nuclei in the kinematics prohibited for free nucleons ("cumulative pions") is studied in the fusing color string model.The model describes the so-called direct mechanism for cumulative production. The other, spectator mechanism dominates in production of cumulative protons but is suppressed for pions. In the model cumulative pions are generated by string fusion which raises the maximal energy of produced partons above the level of the free nucleon kinematics. Momentum and multiplicity sum rules are used to determine the spectra in the deep fragmentation region. Predicted spectra of cumulative pions exponentially fall with the scaling variable $x$ in the interval $1<x<3$ with a slope of the order 5$÷$5.6, which agrees well with the raw data obtained in the recent experiment at RHIC with Cu-Au collisioins. However the agreement is worse for the so-called unfolded data, presumably taking into account corrections due to the expermental set-up and having rather a power-like form.

   hep-phUniverse(2023)·1 citation
8. 08*

   Resummation and renormalization of kinematical effects in inclusive $P$-wave quarkonium production

   Hee Sok Chung🇰🇷

   We investigate the renormalization properties of the shape function formalism for inclusive production of $P$-wave heavy quarkonia, which arises from resumming a class of corrections coming from kinematical effects associated with the motion of the heavy quark and antiquark pair relative to the quarkonium. Such kinematical effects are encoded in the nonperturbative shape functions, which are normalized to the corresponding nonrelativistic QCD long-distance matrix elements. By using the known ultraviolet divergences in the matrix elements, we derive the large-momentum asymptotic behavior of the shape functions. This strongly constrains the form of the shape functions and significantly reduces the dependence on the nonperturbative model. Based on these results we show that the shape function formalism at loop level can be useful in taming the threshold logarithms at large transverse momentum, and at small transverse momentum the kinematical corrections reduce the sizes of ${\chi }_c$ and ${\chi }_b$ cross sections which may improve agreement with measurements.

   hep-phJHEP(2023)·6 citations
9. 09*

   Neutrinoless double beta decay: neutrino mass versus new physics

   Gia Dvali🇩🇪 · Alessio Maiezza🇮🇹 · Goran Senjanovic🇮🇹 · Vladimir Tello🇮🇹

   Neutrinoless double beta decay is the textbook example of lepton number violation, often claimed to be a probe of neutrino Majorana mass. However, it could be triggered by new physics; after all, neutrino Majorana mass requires physics beyond the Standard Model. If at least one electron were right-handed, it would automatically signify new physics rather than neutrino mass. In case both electrons were left-handed, the situation would become rather complicated, and additional effort would be needed to untangle the source for this process. We offer a comprehensive study of this issue from both the effective operator approach and the possible UV completions, including the Pati-Salam quark-lepton unification. While neutrino exchange is natural and physically preferred, our findings show that new physics can still be responsible for the neutrinoless double beta decay. In particular, the Pati-Salam theory can do the job, consistently with all the phenomenological and unification constraints, as long as the unification scale lies above 10^12 GeV, albeit at the price of fine-tuning of some scalar masses.

   hep-phPRD(2023)·8 citations
10. 10*

    $B\to X_{c(u)}\ell {\bar{\nu }}_{\ell }\gamma$ and determination of non-perturbative parameters

    Namit Mahajan🇮🇳 · Dayanand Mishra🇮🇳

    This article explores the calculation of non-perturbative parameters present in the matrix element of semileptonic inclusive $B$ decays. These are important for the inclusive determination of the Cabbibo-Kobayashi-Maskawa (CKM) parameters in the standard model. We focus on calculating the rate for radiative inclusive decay, $B\to X_c\ell {\bar{\nu }}_{\ell }\gamma$, where $\gamma$ is hard. Both the radiative and non-radiative ($B\to X_c\ell {\bar{\nu }}_{\ell }$) modes are found to require the same non-perturbative parameters. We propose forming ratios from $B\to X_c\ell {\bar{\nu }}_{\ell }\gamma$ and $B\to X_c\ell {\bar{\nu }}_{\ell }$ widths in different lepton energy ranges. Our results provide an efficient way to unambiguously calculate the non-perturbative parameters, especially when combined with total width calculations of $B\to X_c\ell {\bar{\nu }}_{\ell }$. This is shown explicitly by working to $\mathcal{O}(1/m_b)$ and determining ${\lambda }_1$ and ${\lambda }_2$.

    hep-phhep-exPRD(2024)·1 citation
11. 11*

    On Consistent Kinetic Mixing and the Higgs Low-Energy Theorems

    Patrick Foldenauer🇪🇸

    A popular class of extensions of the Standard Model (SM) are models of a new Abelian gauge boson $X$, called $dark$ or $hiddenphoton$, that kinetically mixes with the SM photon. We revisit the matching procedure of kinetic mixing terms in the electroweak symmetric phase to the ones in the broken phase. Our central finding is that in order to obtain the correct matching prescription one has to take into account mixing of the hidden photon with the neutral component of the weak $SU(2{)}_L$ bosons. This mixing is generated by a dimension-six operator and, in theories where $SU(2{)}_L$ multiplets are charged under the novel Abelian gauge group, is necessarily induced at the one-loop level. We illustrate this matching procedure for the loop-generated kinetic mixing in $U(1{)}_{L_{\mu }-L_{\tau }}$. Furthermore, we show how to obtain general expressions for the Higgs decay amplitudes to two neutral vector bosons from the vacuum polarisation amplitudes via the low-energy theorems. As an application, we derive general expression for the branching ratios of the decays $h\to \gamma X$ and $h\to XX$ in $U(1{)}_{B-L}$.

    hep-phPoS(2024)·0 citations
12. 12*

    Small-$x$ Quark and Gluon Helicity Contributions to the Proton Spin Puzzle

    Yossathorn Tawabutr🇫🇮

    A small-$x$ helicity evolution has been derived in 2016-18 and received an important modification in 2022. This article discusses its general framework and summarizes the recent theoretical developments, including the asymptotic behaviors of helicity PDFs and $g_1$ structure function at small $x$. The latest fits to various polarized scattering data are also discussed. The results from this research program will provide important theoretical inputs for the future polarized small-$x$ measurements at the electron-ion collider (EIC).

    hep-phhep-exnucl-exnucl-thActa Phys.Polon.Supp.(2023)·3 citations
13. 13*

    Heavy-Quark spin symmetry breaking in the Born-Oppenheimer approximation

    R. Bruschini🇺🇸

    Heavy-quark spin symmetry is explicitly broken by the mass splitting between a heavy-light pseudoscalar meson and its vector partner. This fact plays a pivotal role in the physics of states whose mass lies close to the threshold of an open-flavor meson pair, like $X(3872)$. We show that this source of heavy-quark spin symmetry breaking can be systematically included within the diabatic representation of the Born-Oppenheimer approximation. We verify that including all the appropriate coupled channels guarantees conservation of total angular momentum, parity, and charge-conjugation parity. This marks a fundamental step towards a unified, first-principles study of quarkonia and meson molecules with hidden flavor.

    hep-phJHEP(2023)·20 citations
14. 14*

    On the coupling of axion-like particles to the top quark

    Fabian Esser🇪🇸 · Maeve Madigan🇬🇧 · Veronica Sanz🇬🇧 · Maria Ubiali🇬🇧

    In this paper we explore the coupling of a light axion-like particle (ALP) to top quarks. We use high-energy LHC probes, and examine both the direct probe to this coupling in associated production of a top-pair with an ALP, and the indirect probe through loop-induced gluon fusion to an ALP leading to top pairs. Using the latest LHC Run II data, we provide the best limit on this coupling. We also compare these limits with those obtained from loop-induced couplings in diboson final states, finding that the $t\bar{t}$+MET channel is the best current handle on this coupling.

    hep-phhep-exJHEP(2023)·46 citations
15. 15*

    Impact of cross-section uncertainties on supernova neutrino spectral parameter fitting in the Deep Underground Neutrino Experiment

    DUNE Collaboration: A. Abed Abud · B. Abi · R. Acciarri · M. A. Acero · M. R. Adames · G. Adamov · M. Adamowski · D. Adams · M. Adinolfi · C. Adriano · A. Aduszkiewicz · J. Aguilar and 1306 other authors

    A primary goal of the upcoming Deep Underground Neutrino Experiment (DUNE) is to measure the $\mathcal{O}(10)$ MeV neutrinos produced by a Galactic core-collapse supernova if one should occur during the lifetime of the experiment. The liquid-argon-based detectors planned for DUNE are expected to be uniquely sensitive to the ${\nu }_e$ component of the supernova flux, enabling a wide variety of physics and astrophysics measurements. A key requirement for a correct interpretation of these measurements is a good understanding of the energy-dependent total cross section $\sigma (E_{\nu })$ for charged-current ${\nu }_e$ absorption on argon. In the context of a simulated extraction of supernova ${\nu }_e$ spectral parameters from a toy analysis, we investigate the impact of $\sigma (E_{\nu })$ modeling uncertainties on DUNE's supernova neutrino physics sensitivity for the first time. We find that the currently large theoretical uncertainties on $\sigma (E_{\nu })$ must be substantially reduced before the ${\nu }_e$ flux parameters can be extracted reliably: in the absence of external constraints, a measurement of the integrated neutrino luminosity with less than 10\% bias with DUNE requires $\sigma (E_{\nu })$ to be known to about 5%. The neutrino spectral shape parameters can be known to better than 10% for a 20% uncertainty on the cross-section scale, although they will be sensitive to uncertainties on the shape of $\sigma (E_{\nu })$. A direct measurement of low-energy ${\nu }_e$-argon scattering would be invaluable for improving the theoretical precision to the needed level.

    ↳ hep-exhep-phnucl-thPRD(2023)·32 citations
16. 16*

    Theoretical and Experimental Constraints for the Equation of State of Dense and Hot Matter

    Rajesh Kumar🇺🇸 · Veronica Dexheimer🇺🇸 · Johannes Jahan🇺🇸 · Jorge Noronha🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸 · Claudia Ratti🇺🇸 · Nico Yunes🇺🇸 · Angel Rodrigo Nava Acuna🇺🇸 · Mark Alford🇺🇸 · Mahmudul Hasan Anik🇺🇸 · Debarati Chatterjee🇮🇳 · Katerina Chatziioannou🇺🇸 and 48 other authors

    This review aims at providing an extensive discussion of modern constraints relevant for dense and hot strongly interacting matter. It includes theoretical first-principle results from lattice and perturbative QCD, as well as chiral effective field theory results. From the experimental side, it includes heavy-ion collision and low-energy nuclear physics results, as well as observations from neutron stars and their mergers. The validity of different constraints, concerning specific conditions and ranges of applicability, is also provided.

    ↳ nucl-thastro-ph.HEgr-qchep-ph+1Living Rev.Rel.(2024)·171 citations
17. 17*

    Flavor structure in magnetized orbifold and blow-up manifold compactification

    Hikaru Uchida🇯🇵

    As the effective field theory of the superstring theory, ten-dimensional $\mathcal{N}=1$ supersymmetric Yang-Mills theory is induced. We consider the ten-dimensional space-time ${\mathcal{M}}_{10}$ as direct products of our four-dimensional space-time ${\mathcal{M}}_4$ and three two-dimensional compact spaces $X_i(i=1,2,3)$, i.e. ${\mathcal{M}}_{10}={\mathcal{M}}_4\times X_2\times X_2\times X_3$. In particular, we consider $X_i$ as a torus, the torus orbifold, and also the blow-up manifold of the torus orbifold with background magnetic fluxes. We discuss the modular symmetry in the magnetized torus and its orbifold compactifications. We find that the modular flavor groups and the representations as well as modular weights of the chiral fields such as quarks and leptons obtained from the magnetized torus as well as the orbifold compactifications can be uniquely determined with the magnetic fluxes. We also discuss the magnetized blow-up manifold compactification in which orbifold singularities are replaced by parts of sphere as a smooth manifold. We find that the chiral zero mode numbers on the blow-up manifold as well as the orbifold can be determined only by the magnetic fluxes including localized fluxes due to the Atiyah-Singer index theorem, and then the degree of freedom of localized fluxes gives new additional chiral zero modes. We also find that the new chiral zero modes correspond to localized modes around the orbifold singularities.

    ↳ hep-thhep-ph4 citations
18. 18*

    Hot QCD White Paper

    M. Arslandok🇺🇸 · S. A. Bass🇺🇸 · A. A. Baty🇺🇸 · I. Bautista🇲🇽 · C. Beattie🇺🇸 · F. Becattini🇮🇹 · R. Bellwied🇺🇸 · Y. Berdnikov🇷🇺 · A. Berdnikov🇷🇺 · J. Bielcik🇨🇿 · J. T. Blair🇺🇸 · F. Bock🇺🇸 and 162 other authors

    Hot QCD physics studies the nuclear strong force under extreme temperature and densities. Experimentally these conditions are achieved via high-energy collisions of heavy ions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). In the past decade, a unique and substantial suite of data was collected at RHIC and the LHC, probing hydrodynamics at the nucleon scale, the temperature dependence of the transport properties of quark-gluon plasma, the phase diagram of nuclear matter, the interaction of quarks and gluons at different scales and much more. This document, as part of the 2023 nuclear science long range planning process, was written to review the progress in hot QCD since the 2015 Long Range Plan for Nuclear Science, as well as highlight the realization of previous recommendations, and present opportunities for the next decade, building on the accomplishments and investments made in theoretical developments and the construction of new detectors. Furthermore, this document provides additional context to support the recommendations voted on at the Joint Hot and Cold QCD Town Hall Meeting, which are reported in a separate document.

    ↳ nucl-exhep-exhep-phnucl-th125 citations
19. 19*

    Exotic Tetraquark states with two $\bar{b}$-quarks and $J^P=0^{+}$ and $1^{+}$ $B_s$ states in a nonperturbatively-tuned Lattice NRQCD setup

    R. J. Hudspith🇩🇪 · D. Mohler🇩🇪

    We use $n_f=2+1$ Wilson-clover gauge-field ensembles from the CLS consortium in a Lattice NRQCD setup to predict the binding energy of a $I(J^P)=0(1^{+})$ $ud\bar{b}\bar{b}$ tetraquark and a $\frac{1}{2}(1^{+})$ $\ell s\bar{b}\bar{b}$ tetraquark. We determine the binding energies with respect to the relevant $B{B}^{\ast }$ and $B_s{B}^{\ast }$ thresholds respectively to be $112.0(13.2)$ MeV for the $ud\bar{b}\bar{b}$, and $46.4(12.3)$ MeV for the $\ell s\bar{b}\bar{b}$. We also determine the ground-state $J^P=0^{+}$ $B_{s0}^{\ast }$ and $1^{+}$ $B_{s1}$ mesons to lie $75.4(14.0)$ and $78.7(13.9)$ MeV below the $BK$ and $B^{\ast }K$ thresholds respectively. Our errors are entirely dominated by systematics due to discretisation effects. To achieve these measurements, we performed a neural network based nonperturbative tuning of the Lattice NRQCD Hamiltonian's parameters against the basic bottomonium spectrum. For all lattice spacings considered we can reproduce the continuum splittings of low-lying bottomonia. It is worth remarking that our nonperturbative tuning parameters deviate from 1 by significant amounts, particularly the term $c_2$.

    ↳ hep-lathep-phPRD(2023)·54 citations
20. 20*

    First Simultaneous Determination of Inclusive and Exclusive $\left|V_{ub}\right|$

    Belle Collaboration: L. Cao🇩🇪 · F. Bernlochner🇩🇪 · K. Tackmann🇩🇪 · I. Adachi🇯🇵 · H. Aihara🇯🇵 · S. Al Said · D. M. Asner🇺🇸 · H. Atmacan🇺🇸 · T. Aushev🇷🇺 · R. Ayad🇸🇦 · V. Babu🇩🇪 · S. Bahinipati🇮🇳 and 201 other authors

    The first simultaneous determination of the absolute value of the Cabibbo-Kobayashi-Maskawa matrix element $V_{ub}$ using inclusive and exclusive decays is performed with the full Belle data set at the ${\rm Y}(4S)$ resonance, corresponding to an integrated luminosity of 711 fb${}^{-1}$. We analyze collision events in which one $B$ meson is fully reconstructed in hadronic modes. This allows for the reconstruction of the hadronic $X_u$ system of the semileptonic $b\to u\ell {\bar{\nu }}_{\ell }$ decay. We separate exclusive $B\to \pi \ell {\bar{\nu }}_{\ell }$ decays from other inclusive $B\to X_u\ell {\bar{\nu }}_{\ell }$ and backgrounds with a two-dimensional fit, that utilizes the number of charged pions in the $X_u$ system and the four-momentum transfer $q^2$ between the $B$ and $X_u$ system. Combining our measurement with information from lattice QCD and QCD calculations of the inclusive partial rate as well as external experimental information on the shape of the $B\to \pi \ell {\bar{\nu }}_{\ell }$ form factor, we determine $\left|V_{ub}^{excl.}\right|=(3.78\pm 0.23\pm 0.16\pm 0.14)\times 10^{-3}$ and $\left|V_{ub}^{incl.}\right|=(3.88\pm 0.20\pm 0.31\pm 0.09)\times 10^{-3}$, respectively, with the uncertainties being the statistical error, systematic errors, and theory errors. The ratio of $\left|V_{ub}^{excl.}\right|/\left|V_{ub}^{incl.}\right|=0.97\pm 0.12$ is compatible with unity.

    ↳ hep-exhep-phPRL(2023)·15 citations
21. 21*

    The role of soft photon injection and heating in 21 cm cosmology

    Sandeep Kumar Acharya🇬🇧 · Bryce Cyr🇬🇧 · Jens Chluba🇬🇧

    The ARCADE radio excess and EDGES measurement remain puzzling. A link between the two has been previously considered, however, in this work we highlight an important related effect that was not analyzed in detail before. By performing cosmological thermalization calculations with soft photon injection using {\tt CosmoTherm}, we show that for the 21 cm signal generation the interplay between enhanced radio spectral distortions and the associated heating can hide a significant radio excess before the reionzation era. We illustrate this effect for a simple power-law soft photon source in decaying particle scenarios. Even if simplistic, the uncovered link between CMB spectral distortions and 21 cm cosmology should apply to a much broader range of scenarios. This could significantly affect the constraints derived from existing and future 21 cm observations on the evolution of the ambient radio background. In particular, scenarios that would be ruled out by existing data without heating could become viable solutions once the heating is accounted for in the modelling. Our calculations furthermore highlight the importance of global 21 cm observations reaching into the dark ages, where various scenarios can potentially be distinguished.

    ↳ astro-ph.COastro-ph.HEhep-phMNRAS(2023)·34 citations
22. 22*

    The ESSnuSB design study: overview and future prospects

    ESSnuSB Collaboration: A. Alekou🇨🇭 · E. Baussan🇫🇷 · A.K. Bhattacharyya🇸🇪 · N. Blaskovic Kraljevic🇸🇪 · M. Blennow🇸🇪 · M. Bogomilov🇧🇬 · B. Bolling🇸🇪 · E. Bouquerel🇫🇷 · F. Bramati🇮🇹 · A. Branca🇮🇹 · O. Buchan🇸🇪 · A. Burgman🇸🇪 and 73 other authors

    ESSnuSB is a design study for an experiment to measure the CP violation in the leptonic sector at the second neutrino oscillation maximum using a neutrino beam driven by the uniquely powerful ESS linear accelerator. The reduced impact of systematic errors on sensitivity at the second maximum allows for a very precise measurement of the CP violating parameter. This review describes the fundamental advantages of measurement at the 2nd maximum, the necessary upgrades to the ESS linac in order to produce a neutrino beam, the near and far detector complexes, the expected physics reach of the proposed ESSnuSB experiment, concluding with the near future developments aimed at the project realization.

    ↳ hep-exhep-phphysics.ins-detUniverse(2023)·41 citations
23. 23*

    Primordial black holes and stochastic inflation beyond slow roll: I -- noise matrix elements

    Swagat S. Mishra🇬🇧 · Edmund J. Copeland🇬🇧 · Anne M. Green🇬🇧

    Primordial Black Holes (PBHs) may form in the early Universe, from the gravitational collapse of large density perturbations, generated by large quantum fluctuations during inflation. Since PBHs form from rare over-densities, their abundance is sensitive to the tail of the primordial probability distribution function (PDF) of the perturbations. It is therefore important to calculate the full PDF of the perturbations, which can be done non-perturbatively using the 'stochastic inflation' framework. In single field inflation models generating large enough perturbations to produce an interesting abundance of PBHs requires violation of slow roll. It is therefore necessary to extend the stochastic inflation formalism beyond slow roll. A crucial ingredient for this are the stochastic noise matrix elements of the inflaton potential. We carry out analytical and numerical calculations of these matrix elements for a potential with a feature which violates slow roll and produces large, potentially PBH generating, perturbations. We find that the transition to an ultra slow-roll phase results in the momentum induced noise terms becoming larger than the field noise whilst each of them falls exponentially for a few e-folds. The noise terms then start rising with their original order restored, before approaching constant values which depend on the nature of the slow roll parameters in the post transition epoch. This will significantly impact the quantum diffusion of the coarse-grained inflaton field, and hence the PDF of the perturbations and the PBH mass fraction.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2023)·50 citations
24. 24*

    Non-thermal moduli production during preheating in $\alpha$-attractor inflation models

    Khursid Alam🇮🇳 · Mar Bastero-Gil🇪🇸 · Koushik Dutta🇮🇳 · H. V. Ragavendra🇮🇳

    Production of gravitationally coupled light moduli fields must be suppressed in the early universe, so that its decay products do not alter Big Bang Nucleosynthesis (BBN) predictions for light elements. On the other hand, the moduli quanta can be copiously produced non-thermally during preheating after the end of inflation. In this work, we study the production of moduli in the $\alpha$-attractor inflationary model through parametric resonances. For our case, where the inflationary potential at its minimum is quartic, the inflaton field self-resonates, and subsequently induces large production of moduli particles. We find that this production is suppressed for small values of $\alpha$. Combining semi-analytical estimation and numerical lattice simulations, we infer the parametric dependence on $\alpha$ and learn that $\alpha$ needs to be $\lesssim 10^{-8}{m}_{\mathrm{Pl}}^2$ to be consistent with BBN. This in turn predicts an upper bound on the energy scale of inflation and on the reheating temperature.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2023)·6 citations
25. 25*

    Cumulants from fluctuating width of rapidity distribution

    Michał Barej🇵🇱 · Adam Bzdak🇵🇱

    In relativistic heavy-ion collisions, the longitudinal fluctuations of the fireball density caused, e.g., by baryon stopping fluctuations result in event-by-event modifications of the shape of the proton rapidity density distribution. The multiparticle rapidity correlation functions due to the varying distribution width of the proton rapidity density in central Au+Au collisions at low energies are derived. The cumulant ratios are calculated and discussed in the context of the recent STAR Collaboration results. We find that the cumulant ratios for small width fluctuations seem to be universal.

    ↳ nucl-thhep-exhep-phnucl-exPRC(2023)·1 citation
26. 26*

    The strong backreaction regime in axion inflation

    Daniel G. Figueroa🇪🇸 · Joanes Lizarraga🇪🇸 · Ander Urio🇪🇸 · Jon Urrestilla🇪🇸

    We study the non-linear dynamics of axion inflation, capturing for the first time the inhomogeneity and full dynamical range during strong backreaction, till the end of inflation. Accounting for inhomogeneous effects leads to a number of new relevant results, compared to spatially homogeneous studies: i) the number of extra efoldings beyond slow roll inflation increases very rapidly with the coupling, ii) oscillations of the inflaton velocity are attenuated, iii) the tachyonic gauge field helicity spectrum is smoothed out (i.e.~the spectral oscillatory features disappear), broadened, and shifted to smaller scales, and iv) the non-tachyonic helicity is excited, reducing the chiral asymmetry, now scale dependent. Our results are expected to impact strongly on the phenomenology and observability of axion inflation, including gravitational wave generation and primordial black hole production.

    ↳ astro-ph.COhep-phPRL(2023)·82 citations
27. 27*

    Constraining ultralight dark matter using the Fermi-LAT pulsar timing array

    Zi-Qing Xia🇨🇳 · Tian-Peng Tang🇨🇳 · Xiaoyuan Huang🇨🇳 · Qiang Yuan🇨🇳 · Yi-Zhong Fan🇨🇳

    Ultralight dark matter (ULDM) is proposed as a theoretical candidate of dark matter particles with masses of approximately $10^{-22}$ eV. The interactions between ULDM particles and standard model particles would cause variations in pulse arrival times of millisecond pulsars, which means that the pulsar timing array (PTA) can be used to indirectly detect ULDM. In this letter, we use the gamma-ray PTA composed of 29 millisecond pulsars observed by the Fermi Large Area Telescope (Fermi-LAT) to test four ULDM effects, including gravitational effects for generalized ULDM with different Spin-0/1, the fifth-force coupling effect of dark photon, and the modified gravitational effect of the Spin-2 ULDM. The gamma-ray pulsar timing is not affected by the ionized interstellar medium and suffers relatively simple noises, unlike that of the radio band. Our work is the first time that the gamma-ray PTA has been used to search for the ULDM. No significant signals of ULDM are found based on the Fermi-LAT PTA for all four kinds of ULDM models. Constraints on ULDM parameters are set with the 95% confidence level, which provides a complementary check of the nondetection of ULDM for radio PTAs and direct detection experiments.

    ↳ astro-ph.HEastro-ph.COgr-qchep-phPRD(2023)·26 citations

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