Pub Date : 2023-11-13DOI: 10.48550/arxiv.2311.07250
Lykou, F., Ábrahám, P., de Miera, F. Cruz-Sáenz, Varga, J., Kóspál, Á., Bouwman, J., Chen, L., Kraus, S., Sitko, M. L., Russell, R. W., Pikhartova, M.
In this work, we study the silicate dust content in the disk of one of the youngest eruptive stars, V900 Mon, at the highest angular resolution probing down to the inner 10 au of said disk, and study the historical evolution of the system traced in part by a newly discovered emission clump. We performed high-angular resolution mid-infrared interferometric observations of V900 Mon with MATISSE/VLTI with a spatial coverage ranging from 38-m to 130-m baselines, and compared them to archival MIDI/VLTI data. We also mined and re-analyzed archival optical and infrared photometry of the star to study its long-term evolution since its eruption in the 1990s. We complemented our findings with integral field spectroscopy data from MUSE/VLT. The MATISSE/VLTI data suggest a radial variation of the silicate feature in the dusty disk, whereby at large spatial scales ($geq10$ au) the protostellar disk's emission is dominated by large-sized ($geq1,mu m$) silicate grains, while at smaller spatial scales and closer to the star ($leq5$ au), silicate emission is absent suggesting self-shielding. We propose that the self-shielding may be the result of small dust grains at the base of the collimated CO outflow previously detected by ALMA. A newly discovered knot in the MUSE/VLT data, located at a projected distance approximately 27,000 au from the star, is co-aligned with the molecular gas outflow at a P.A. of $250^o$ ($pm5^o$) consistent with the position angle and inclination of the disk. The knot is seen in emission in H$alpha$, [N II], and the [S II] doublet and its kinematic age is about 5150 years. This ejected material could originate from a previous eruption.
{"title":"The disk of the eruptive protostar V900 Mon; a MATISSE/VLTI and MUSE/VLT\u0000 perspective","authors":"Lykou, F., Ábrahám, P., de Miera, F. Cruz-Sáenz, Varga, J., Kóspál, Á., Bouwman, J., Chen, L., Kraus, S., Sitko, M. L., Russell, R. W., Pikhartova, M.","doi":"10.48550/arxiv.2311.07250","DOIUrl":"https://doi.org/10.48550/arxiv.2311.07250","url":null,"abstract":"In this work, we study the silicate dust content in the disk of one of the youngest eruptive stars, V900 Mon, at the highest angular resolution probing down to the inner 10 au of said disk, and study the historical evolution of the system traced in part by a newly discovered emission clump. We performed high-angular resolution mid-infrared interferometric observations of V900 Mon with MATISSE/VLTI with a spatial coverage ranging from 38-m to 130-m baselines, and compared them to archival MIDI/VLTI data. We also mined and re-analyzed archival optical and infrared photometry of the star to study its long-term evolution since its eruption in the 1990s. We complemented our findings with integral field spectroscopy data from MUSE/VLT. The MATISSE/VLTI data suggest a radial variation of the silicate feature in the dusty disk, whereby at large spatial scales ($geq10$ au) the protostellar disk's emission is dominated by large-sized ($geq1,mu m$) silicate grains, while at smaller spatial scales and closer to the star ($leq5$ au), silicate emission is absent suggesting self-shielding. We propose that the self-shielding may be the result of small dust grains at the base of the collimated CO outflow previously detected by ALMA. A newly discovered knot in the MUSE/VLT data, located at a projected distance approximately 27,000 au from the star, is co-aligned with the molecular gas outflow at a P.A. of $250^o$ ($pm5^o$) consistent with the position angle and inclination of the disk. The knot is seen in emission in H$alpha$, [N II], and the [S II] doublet and its kinematic age is about 5150 years. This ejected material could originate from a previous eruption.","PeriodicalId":496270,"journal":{"name":"arXiv (Cornell University)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136352657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-13DOI: 10.48550/arxiv.2311.07429
Gorbar, E. V., Momot, A. I., Prikhodko, O. O., Teslyk, O. M.
We study chirality production in the pseudoscalar inflation model of magnetogenesis taking into account the Schwinger effect and particle collisions in plasma in the relaxation time approximation. We consider the Schwinger production of one Dirac fermion species by an Abelian gauge field in two cases: (i) the fermion carries only the weak charge with respect to the U(1) group and (ii) it is also charged with respect to another strongly coupled gauge group. While the gradient-expansion formalism is employed for the description of the evolution of gauge field, plasma is described by hydrodynamical approach which allows us to determine the number, energy density, and chirality of produced fermions. It is found that while chirality production is very efficient for both, weakly and strongly interacting fermions, the resulting gauge field is typically stronger in the case of strongly interacting fermions due to suppression of the Schwinger conductivity by particle collisions.
{"title":"Hydrodynamical approach to chirality production during axion inflation","authors":"Gorbar, E. V., Momot, A. I., Prikhodko, O. O., Teslyk, O. M.","doi":"10.48550/arxiv.2311.07429","DOIUrl":"https://doi.org/10.48550/arxiv.2311.07429","url":null,"abstract":"We study chirality production in the pseudoscalar inflation model of magnetogenesis taking into account the Schwinger effect and particle collisions in plasma in the relaxation time approximation. We consider the Schwinger production of one Dirac fermion species by an Abelian gauge field in two cases: (i) the fermion carries only the weak charge with respect to the U(1) group and (ii) it is also charged with respect to another strongly coupled gauge group. While the gradient-expansion formalism is employed for the description of the evolution of gauge field, plasma is described by hydrodynamical approach which allows us to determine the number, energy density, and chirality of produced fermions. It is found that while chirality production is very efficient for both, weakly and strongly interacting fermions, the resulting gauge field is typically stronger in the case of strongly interacting fermions due to suppression of the Schwinger conductivity by particle collisions.","PeriodicalId":496270,"journal":{"name":"arXiv (Cornell University)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136352668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-13DOI: 10.48550/arxiv.2311.07389
Amit, Guy, Levy, Mosh, Mirsky, Yisroel
Deep neural networks are normally executed in the forward direction. However, in this work, we identify a vulnerability that enables models to be trained in both directions and on different tasks. Adversaries can exploit this capability to hide rogue models within seemingly legitimate models. In addition, in this work we show that neural networks can be taught to systematically memorize and retrieve specific samples from datasets. Together, these findings expose a novel method in which adversaries can exfiltrate datasets from protected learning environments under the guise of legitimate models. We focus on the data exfiltration attack and show that modern architectures can be used to secretly exfiltrate tens of thousands of samples with high fidelity, high enough to compromise data privacy and even train new models. Moreover, to mitigate this threat we propose a novel approach for detecting infected models.
{"title":"Transpose Attack: Stealing Datasets with Bidirectional Training","authors":"Amit, Guy, Levy, Mosh, Mirsky, Yisroel","doi":"10.48550/arxiv.2311.07389","DOIUrl":"https://doi.org/10.48550/arxiv.2311.07389","url":null,"abstract":"Deep neural networks are normally executed in the forward direction. However, in this work, we identify a vulnerability that enables models to be trained in both directions and on different tasks. Adversaries can exploit this capability to hide rogue models within seemingly legitimate models. In addition, in this work we show that neural networks can be taught to systematically memorize and retrieve specific samples from datasets. Together, these findings expose a novel method in which adversaries can exfiltrate datasets from protected learning environments under the guise of legitimate models. We focus on the data exfiltration attack and show that modern architectures can be used to secretly exfiltrate tens of thousands of samples with high fidelity, high enough to compromise data privacy and even train new models. Moreover, to mitigate this threat we propose a novel approach for detecting infected models.","PeriodicalId":496270,"journal":{"name":"arXiv (Cornell University)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136352681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Smith-Purcell radiation (SPR) occurs when an electron skims above a spatial grating, but the fixed momentum compensation from the static grating imposes limitations on the emission wavelength. It has been discovered that a temporally periodic system can provide energy compensation to generate light emissions in free space. Here, we introduce temporal SPR (t-SPR) emerging from a time grating and propose a generalized t-SPR dispersion equation to predict the relationship between radiation frequency, direction, electron velocity, modulation period, and harmonic orders. Compared to conventional SPR, t-SPR can: 1) Provide a versatile platform for manipulating SPR emission through temporal modulation (e.g., period, amplitude, wave shape). 2) Exhibit strong robustness to the electron-grating separation, alleviating the constraints associated with extreme electron near-field excitation. 3) Introduce additional energy channels through temporal modulation, enhancing and amplifying emission.
{"title":"Smith-Purcell radiation from time grating","authors":"Zhu, Juan-Feng, Nussupbekov, Ayan, Zhou, Wenjie, Song, Zicheng, Wang, Xuchen, Zhang, Zi-Wen, Du, Chao-Hai, Bai, Ping, Png, Ching Eng, Qiu, Cheng-Wei, Wu, Lin","doi":"10.48550/arxiv.2311.07381","DOIUrl":"https://doi.org/10.48550/arxiv.2311.07381","url":null,"abstract":"Smith-Purcell radiation (SPR) occurs when an electron skims above a spatial grating, but the fixed momentum compensation from the static grating imposes limitations on the emission wavelength. It has been discovered that a temporally periodic system can provide energy compensation to generate light emissions in free space. Here, we introduce temporal SPR (t-SPR) emerging from a time grating and propose a generalized t-SPR dispersion equation to predict the relationship between radiation frequency, direction, electron velocity, modulation period, and harmonic orders. Compared to conventional SPR, t-SPR can: 1) Provide a versatile platform for manipulating SPR emission through temporal modulation (e.g., period, amplitude, wave shape). 2) Exhibit strong robustness to the electron-grating separation, alleviating the constraints associated with extreme electron near-field excitation. 3) Introduce additional energy channels through temporal modulation, enhancing and amplifying emission.","PeriodicalId":496270,"journal":{"name":"arXiv (Cornell University)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136352682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-13DOI: 10.48550/arxiv.2311.07382
Alexandersson, Per, Oğuz, Ezgi Kantarci
We generalize several classical results about Schur functions to the family of cylindric Schur functions. First, we give a combinatorial proof of a Murnaghan--Nakayama formula for expanding cylindric Schur functions in the power-sum basis. We also explore some cases where this formula is cancellation-free. The second result is polynomiality of Kostka coefficients associated with stretched row-flagged skew Schur functions. This implies polynomiality of stretched cylindric Kostka coefficients. This generalizes a result by E. Rassart from 2004. Finally, we also show the saturation property for the row-flagged skew Kostka coefficients which also implies the saturation property for cylindric Schur functions.
{"title":"Cylindric Schur functions","authors":"Alexandersson, Per, Oğuz, Ezgi Kantarci","doi":"10.48550/arxiv.2311.07382","DOIUrl":"https://doi.org/10.48550/arxiv.2311.07382","url":null,"abstract":"We generalize several classical results about Schur functions to the family of cylindric Schur functions. First, we give a combinatorial proof of a Murnaghan--Nakayama formula for expanding cylindric Schur functions in the power-sum basis. We also explore some cases where this formula is cancellation-free. The second result is polynomiality of Kostka coefficients associated with stretched row-flagged skew Schur functions. This implies polynomiality of stretched cylindric Kostka coefficients. This generalizes a result by E. Rassart from 2004. Finally, we also show the saturation property for the row-flagged skew Kostka coefficients which also implies the saturation property for cylindric Schur functions.","PeriodicalId":496270,"journal":{"name":"arXiv (Cornell University)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136352684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-13DOI: 10.48550/arxiv.2311.07290
Pardo, T., Amaré, J., Apilluelo, J., Cebrián, S., Cintas, D., Coarasa, I., García, E., Martínez, M., Oliván, M. A., Ortigoza, Y., de Solórzano, A. Ortiz, Pellicer, M., Puimedón, J., Salinas, A., Sarsa, M. L., Villar, P.
ANAIS is a direct dark matter detection experiment whose goal is to confirm or refute in a model independent way the positive annual modulation signal claimed by DAMA/LIBRA. Consisting of 112.5 kg of NaI(Tl) scintillators, ANAIS-112 is taking data at the Canfranc Underground Laboratory in Spain since August, 2017. Results corresponding to the analysis of three years of data are compatible with the absence of modulation and incompatible with DAMA/LIBRA. However, testing this signal relies on the knowledge of the scintillation quenching factors (QF), which measure the relative efficiency for the conversion into light of the nuclear recoil energy with respect to the same energy deposited by electrons. Previous measurements of the QF in NaI(Tl) show a large dispersion. Consequently, in order to better understand the response of the ANAIS-112 detectors to nuclear recoils, a specific neutron calibration program has been developed. This program combines two different approaches: on the one hand, QF measurements were carried out in a monoenergetic neutron beam; on the other hand, the study presented here aims at the evaluation of the QF by exposing directly the ANAIS-112 crystals to neutrons from low activity $^{252}$Cf sources, placed outside the lead shielding. Comparison between these onsite neutron measurements and detailed GEANT4 simulations will be presented, confirming that this approach allows testing different QF models.
{"title":"Neutron calibrations in dark matter searches: the ANAIS-112 case","authors":"Pardo, T., Amaré, J., Apilluelo, J., Cebrián, S., Cintas, D., Coarasa, I., García, E., Martínez, M., Oliván, M. A., Ortigoza, Y., de Solórzano, A. Ortiz, Pellicer, M., Puimedón, J., Salinas, A., Sarsa, M. L., Villar, P.","doi":"10.48550/arxiv.2311.07290","DOIUrl":"https://doi.org/10.48550/arxiv.2311.07290","url":null,"abstract":"ANAIS is a direct dark matter detection experiment whose goal is to confirm or refute in a model independent way the positive annual modulation signal claimed by DAMA/LIBRA. Consisting of 112.5 kg of NaI(Tl) scintillators, ANAIS-112 is taking data at the Canfranc Underground Laboratory in Spain since August, 2017. Results corresponding to the analysis of three years of data are compatible with the absence of modulation and incompatible with DAMA/LIBRA. However, testing this signal relies on the knowledge of the scintillation quenching factors (QF), which measure the relative efficiency for the conversion into light of the nuclear recoil energy with respect to the same energy deposited by electrons. Previous measurements of the QF in NaI(Tl) show a large dispersion. Consequently, in order to better understand the response of the ANAIS-112 detectors to nuclear recoils, a specific neutron calibration program has been developed. This program combines two different approaches: on the one hand, QF measurements were carried out in a monoenergetic neutron beam; on the other hand, the study presented here aims at the evaluation of the QF by exposing directly the ANAIS-112 crystals to neutrons from low activity $^{252}$Cf sources, placed outside the lead shielding. Comparison between these onsite neutron measurements and detailed GEANT4 simulations will be presented, confirming that this approach allows testing different QF models.","PeriodicalId":496270,"journal":{"name":"arXiv (Cornell University)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136352796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-13DOI: 10.48550/arxiv.2311.07288
ATLAS Collaboration
We report the highest-energy observation of entanglement, in top$-$antitop quark events produced at the Large Hadron Collider, using a proton$-$proton collision data set with a center-of-mass energy of $sqrt{s}=13$ TeV and an integrated luminosity of 140 fb$^{-1}$ recorded with the ATLAS experiment. Spin entanglement is detected from the measurement of a single observable $D$, inferred from the angle between the charged leptons in their parent top- and antitop-quark rest frames. The observable is measured in a narrow interval around the top$-$antitop quark production threshold, where the entanglement detection is expected to be significant. It is reported in a fiducial phase space defined with stable particles to minimize the uncertainties that stem from limitations of the Monte Carlo event generators and the parton shower model in modelling top-quark pair production. The entanglement marker is measured to be $D=-0.547 pm 0.002~text{(stat.)} pm 0.021~text{(syst.)}$ for $340 < m_{tbar{t}} < 380 $ GeV. The observed result is more than five standard deviations from a scenario without entanglement and hence constitutes both the first observation of entanglement in a pair of quarks and the highest-energy observation of entanglement to date.
{"title":"Observation of quantum entanglement in top-quark pairs using the ATLAS\u0000 detector","authors":"ATLAS Collaboration","doi":"10.48550/arxiv.2311.07288","DOIUrl":"https://doi.org/10.48550/arxiv.2311.07288","url":null,"abstract":"We report the highest-energy observation of entanglement, in top$-$antitop quark events produced at the Large Hadron Collider, using a proton$-$proton collision data set with a center-of-mass energy of $sqrt{s}=13$ TeV and an integrated luminosity of 140 fb$^{-1}$ recorded with the ATLAS experiment. Spin entanglement is detected from the measurement of a single observable $D$, inferred from the angle between the charged leptons in their parent top- and antitop-quark rest frames. The observable is measured in a narrow interval around the top$-$antitop quark production threshold, where the entanglement detection is expected to be significant. It is reported in a fiducial phase space defined with stable particles to minimize the uncertainties that stem from limitations of the Monte Carlo event generators and the parton shower model in modelling top-quark pair production. The entanglement marker is measured to be $D=-0.547 pm 0.002~text{(stat.)} pm 0.021~text{(syst.)}$ for $340 < m_{tbar{t}} < 380 $ GeV. The observed result is more than five standard deviations from a scenario without entanglement and hence constitutes both the first observation of entanglement in a pair of quarks and the highest-energy observation of entanglement to date.","PeriodicalId":496270,"journal":{"name":"arXiv (Cornell University)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136352799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-13DOI: 10.48550/arxiv.2311.07295
Sun, G.
SOLPS-ITER simulation is performed to reproduce the X-point radiator recently observed in nitrogen-seeded TCV experiments, which is a scenario that may be favorable to solve the power exhaust problems in future fusion devices. The simulations reveal the transition from the detached regime without XPR to the XPR regime, when increasing the nitrogen seeding rate. A cold X-point core surrounded by ionizing and radiative mentals is formed inside the separatrix and slightly above the X-point, where more than 90% of the total input power is dissipated. The cold X-point core exhibits a temperature of approximately 1eV and features high recombination rate to host the convective fluxes from the ionizing mental. Increasing nitrogen seeding rate also moves the nitrogen ionization front away from the target faster than the nitrogen stagnation point, which enhances the divertor nitrogen leakage to the main chamber and benefits the XPR region cooling. Carbon radiation decreases as the nitrogen seeding increases, and carbon radiation contributes to above 5% of the core impurity radiation before entering the XPR, which decreases to 2.8% when reaching the XPR. Both baffled and unbaffled divertor geometries are simulated and compared, showing that baffles facilitate the access to XPR by increasing the X-point neutral density, but requires higher seeding rate to enter the XPR regime.
{"title":"SOLPS-ITER simulation of an X-point radiator in TCV","authors":"Sun, G.","doi":"10.48550/arxiv.2311.07295","DOIUrl":"https://doi.org/10.48550/arxiv.2311.07295","url":null,"abstract":"SOLPS-ITER simulation is performed to reproduce the X-point radiator recently observed in nitrogen-seeded TCV experiments, which is a scenario that may be favorable to solve the power exhaust problems in future fusion devices. The simulations reveal the transition from the detached regime without XPR to the XPR regime, when increasing the nitrogen seeding rate. A cold X-point core surrounded by ionizing and radiative mentals is formed inside the separatrix and slightly above the X-point, where more than 90% of the total input power is dissipated. The cold X-point core exhibits a temperature of approximately 1eV and features high recombination rate to host the convective fluxes from the ionizing mental. Increasing nitrogen seeding rate also moves the nitrogen ionization front away from the target faster than the nitrogen stagnation point, which enhances the divertor nitrogen leakage to the main chamber and benefits the XPR region cooling. Carbon radiation decreases as the nitrogen seeding increases, and carbon radiation contributes to above 5% of the core impurity radiation before entering the XPR, which decreases to 2.8% when reaching the XPR. Both baffled and unbaffled divertor geometries are simulated and compared, showing that baffles facilitate the access to XPR by increasing the X-point neutral density, but requires higher seeding rate to enter the XPR regime.","PeriodicalId":496270,"journal":{"name":"arXiv (Cornell University)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136352801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present a general framework for designing efficient algorithms for unsupervised learning problems, such as mixtures of Gaussians and subspace clustering. Our framework is based on a meta algorithm that learns arithmetic circuits in the presence of noise, using lower bounds. This builds upon the recent work of Garg, Kayal and Saha (FOCS 20), who designed such a framework for learning arithmetic circuits without any noise. A key ingredient of our meta algorithm is an efficient algorithm for a novel problem called Robust Vector Space Decomposition. We show that our meta algorithm works well when certain matrices have sufficiently large smallest non-zero singular values. We conjecture that this condition holds for smoothed instances of our problems, and thus our framework would yield efficient algorithms for these problems in the smoothed setting.
{"title":"Learning Arithmetic Formulas in the Presence of Noise: A General\u0000 Framework and Applications to Unsupervised Learning","authors":"Chandra, Pritam, Garg, Ankit, Kayal, Neeraj, Mittal, Kunal, Sinha, Tanmay","doi":"10.48550/arxiv.2311.07284","DOIUrl":"https://doi.org/10.48550/arxiv.2311.07284","url":null,"abstract":"We present a general framework for designing efficient algorithms for unsupervised learning problems, such as mixtures of Gaussians and subspace clustering. Our framework is based on a meta algorithm that learns arithmetic circuits in the presence of noise, using lower bounds. This builds upon the recent work of Garg, Kayal and Saha (FOCS 20), who designed such a framework for learning arithmetic circuits without any noise. A key ingredient of our meta algorithm is an efficient algorithm for a novel problem called Robust Vector Space Decomposition. We show that our meta algorithm works well when certain matrices have sufficiently large smallest non-zero singular values. We conjecture that this condition holds for smoothed instances of our problems, and thus our framework would yield efficient algorithms for these problems in the smoothed setting.","PeriodicalId":496270,"journal":{"name":"arXiv (Cornell University)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136352810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-13DOI: 10.48550/arxiv.2311.07378
Mitin, A. V., Gusev, A. A., Chuluunbaatar, O., Vinitsky, S. I., Derbov, V. L., Hai, Luong Le
This review outlines the main results which show the dual nature of the chemical bond in diatomic beryllium molecule in the ground $X^1Sigma_g^+$ state. It has been shown that the beryllium atoms are covalently bound at low-lying vibrational energy levels ({nu}=0-4), while at higher ones ({nu}=5-11) they are bound by van der Waals forces near the right turning points. High precision ab initio quantum calculations of Be$_2$ resulted in the development of the modified expanded Morse oscillator potential function which contains all twelve vibrational energy levels [A.V. Mitin, Chem. Phys. Lett. 682, 30 (2017)]. The dual nature of chemical bond in Be$_2$ is evidenced as a sharp corner on the attractive branch of the ground state potential curve. Moreover, it has been found that the Douglas-Kroll-Hess relativistic corrections also show a sharp corner when presented in dependence on the internuclear separation. The difference in energy between the extrapolated and calculated multi-reference configuration interaction energies in dependence on the internuclear separation also exhibits singular point in the same region. The other problems of ab initio quantum calculations of the beryllium dimer are also discussed. Calculated spectrum of vibrational-rotational bound states and new metastable states of the beryllium dimer in the ground state important for laser spectroscopy are presented. The vibration problem was solved for the modified expanded Morse oscillator potential function and for the potential function obtained with Slater-type orbitals [M. Lesiuk et al, Chem. Theory Comput. 15, 2470 (2019)]. The theoretical upper and lower estimates of the spectrum of vibrational-rotational bound states and the spectrum of rotational-vibrational metastable states with complex-valued energy eigenvalues and the scattering length in the beryllium dimer are presented.
{"title":"Unusual chemical bond and spectrum of beryllium dimer in ground\u0000 $X^1Sigma_g^+$ state","authors":"Mitin, A. V., Gusev, A. A., Chuluunbaatar, O., Vinitsky, S. I., Derbov, V. L., Hai, Luong Le","doi":"10.48550/arxiv.2311.07378","DOIUrl":"https://doi.org/10.48550/arxiv.2311.07378","url":null,"abstract":"This review outlines the main results which show the dual nature of the chemical bond in diatomic beryllium molecule in the ground $X^1Sigma_g^+$ state. It has been shown that the beryllium atoms are covalently bound at low-lying vibrational energy levels ({nu}=0-4), while at higher ones ({nu}=5-11) they are bound by van der Waals forces near the right turning points. High precision ab initio quantum calculations of Be$_2$ resulted in the development of the modified expanded Morse oscillator potential function which contains all twelve vibrational energy levels [A.V. Mitin, Chem. Phys. Lett. 682, 30 (2017)]. The dual nature of chemical bond in Be$_2$ is evidenced as a sharp corner on the attractive branch of the ground state potential curve. Moreover, it has been found that the Douglas-Kroll-Hess relativistic corrections also show a sharp corner when presented in dependence on the internuclear separation. The difference in energy between the extrapolated and calculated multi-reference configuration interaction energies in dependence on the internuclear separation also exhibits singular point in the same region. The other problems of ab initio quantum calculations of the beryllium dimer are also discussed. Calculated spectrum of vibrational-rotational bound states and new metastable states of the beryllium dimer in the ground state important for laser spectroscopy are presented. The vibration problem was solved for the modified expanded Morse oscillator potential function and for the potential function obtained with Slater-type orbitals [M. Lesiuk et al, Chem. Theory Comput. 15, 2470 (2019)]. The theoretical upper and lower estimates of the spectrum of vibrational-rotational bound states and the spectrum of rotational-vibrational metastable states with complex-valued energy eigenvalues and the scattering length in the beryllium dimer are presented.","PeriodicalId":496270,"journal":{"name":"arXiv (Cornell University)","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136352811","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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